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Sample records for east formation petrology

  1. Coal geology of the Paleocene-Eocene Calvert Bluff Formation (Wilcox Group) and the Eocene Manning Formation (Jackson Group) in east-central Texas; field trip guidebook for the Society for Organic Petrology, Twelfth Annual Meeting, The Woodlands, Texas, August 30, 1995

    Science.gov (United States)

    Warwick, Peter D.; Crowley, Sharon S.

    1995-01-01

    The Jackson and Wilcox Groups of eastern Texas (fig. 1) are the major lignite producing intervals in the Gulf Region. Within these groups, the major lignite-producing formations are the Paleocene-Eocene Calvert Bluff Formation (Wilcox) and the Eocene Manning Formation (Jackson). According to the Keystone Coal Industry Manual (Maclean Hunter Publishing Company, 1994), the Gulf Coast basin produces about 57 million short tons of lignite annually. The state of Texas ranks number 6 in coal production in the United States. Most of the lignite is used for electric power generation in mine-mouth power plant facilities. In recent years, particular interest has been given to lignite quality and the distribution and concentration of about a dozen trace elements that have been identified as potential hazardous air pollutants (HAPs) by the 1990 Clean Air Act Amendments. As pointed out by Oman and Finkelman (1994), Gulf Coast lignite deposits have elevated concentrations of many of the HAPs elements (Be, Cd, Co, Cr, Hg, Mn, Se, U) on a as-received gm/mmBtu basis when compared to other United States coal deposits used for fuel in thermo-electric power plants. Although regulations have not yet been established for acceptable emissions of the HAPs elements during coal burning, considerable research effort has been given to the characterization of these elements in coal feed stocks. The general purpose of the present field trip and of the accompanying collection of papers is to investigate how various aspects of east Texas lignite geology might collectively influence the quality of the lignite fuel. We hope that this collection of papers will help future researchers understand the complex, multifaceted interrelations of coal geology, petrology, palynology and coal quality, and that this introduction to the geology of the lignite deposits of east Texas might serve as a stimulus for new ideas to be applied to other coal basins in the U.S. and abroad.

  2. Petrological constraints upon the provenance and genesis of the East Halmahera ophiolite

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    Ballantyne, Paul

    This petrological and geochemical study of the ophiolitic rocks of the island of Halmahera (eastern Indonesia) has resulted in the first detailed interpretation of their tectonomagmatic provenance and suggested modern analogues around the western Pacific margin. Rocks of ophiolitic affinity are common in the eastern part of Halmahera, but structural dismemberment means that an intact ophiolite stratigraphy is not preserved. However, samples representative of each level of a "complete" ophiolite (with the possible exception of sheeted dykes) have been collected. A "mantle sequence" dominated by depleted harzburgite (spinel cr # = 62, olivine Fo 90.4, bulk (Al 2O 3 + CaO) = 1.2 wt%) suggests it is a mantle residue which has undergone a high degree of partial melt extraction. Subordinate lherzolite of relatively enriched chemistry (spinel cr # = 17, olivine Fo 90.4, bulk (Al 2O 3 + CaO) + 4.2 wt%) is interpreted as locally "fertile" upper mantle material. Cumulate rocks are well represented, particularly by olivine-free gabbronorite in which orthopyroxene and clinopyroxene occur in approximately equal modal proportions, and contain clinopyroxene with low TiO 2 (av. 0.29 wt%). Both pyroxenes appear before plagioclase in the crystallisation sequence, and therefore the Halmahera cumulate rocks are distinct from gabbroic rocks formed at mid-oceanic spreading ridges. The cumulus mineralogy is generally comparable with cumulates of the Papuan and Marum ophiolites of New Guinea and with cumulates dredged from the Mariana Trench; it is consistent with open-system crystalisation from a relatively high-Si, high-Mg, low-Ti magma derived from a high degree of partial melting of a lherzolitic mantle source. This correlates with the evidence from the harzburgites and suggests that the ophiolitic rocks were formed in a supra-subduction zone environment. The plutonic rocks are interpreted as resulting from approximately 20% melting of depleted oceanic upper mantle, triggered by

  3. Petrology and SHRIMP zircon geochronology of granulites from Vesleknausen, Lützow-Holm Complex, East Antarctica:Neoarchean magmatism and Neoproterozoic high-grade metamorphism

    Institute of Scientific and Technical Information of China (English)

    Toshiaki Tsunogae; Daniel J. Dunkley; Kenji Horie; Takahiro Endo; Tomoharu Miyamoto; Mutsumi Kato

    2014-01-01

    We report new petrological data and geochronological measurements of granulites from Vesleknausen in the highest-grade section of the Lützow-Holm Complex, part of the Gondwana-assembling collisional orogen in East Antarctica. The locality is dominated by felsic to intermediate orthogneiss (charnockite and minor biotite gneiss), mafic orthogneiss, and hornblende-pyroxene granulite, with deformed and undeformed dykes of metagranite and felsic pegmatite. Pseudosection analysis of charnockite in the system NCKFMASHTO, supported by geothermometry of mafic orthogneiss, was used to infer peak metamorphic temperatures of 750e850 ?C, approximately 150 ?C lower than those estimated for met-asedimentary gneisses from Rundvågshetta, 6 km to the northeast. SHRIMP U-Pb analysis of zircons from feldspar-pyroxene gneiss, which corresponds to a partially molten patch around mafic orthogneiss, yielded a Concordia upper intercept ages of 2507.9 ? 7.4 Ma, corresponding to the time of formation of the magmatic protolith to the orthogneiss. Partial melting during peak metamorphism probably took place between 591 and 548 Ma, as recorded in rims overgrew around magmatic zircon. Our results suggest that Rundvågshetta-Vesleknausen-Strandnibba region in southwestern Lützow-Holm Bay, where orthogneisses are dominant, consists of a single crustal block, possibly formed by ca. 2.5 Ga arc mag-matism. The Neoarchean magmatic terrane was tectonically mingled with other fragments (such as metasedimentary units in northern Lützow-Holm Bay) by subduction/collision events during the as-sembly of Gondwana supercontinent, and subsequently underwent w850 ?C granulite-facies meta-morphosed during Neoproterozoic to Cambrian final collisional event.

  4. Petrology and SHRIMP zircon geochronology of granulites from Vesleknausen, Lützow-Holm Complex, East Antarctica: Neoarchean magmatism and Neoproterozoic high-grade metamorphism

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    Toshiaki Tsunogae

    2014-03-01

    Full Text Available We report new petrological data and geochronological measurements of granulites from Vesleknausen in the highest-grade section of the Lützow-Holm Complex, part of the Gondwana-assembling collisional orogen in East Antarctica. The locality is dominated by felsic to intermediate orthogneiss (charnockite and minor biotite gneiss, mafic orthogneiss, and hornblende-pyroxene granulite, with deformed and undeformed dykes of metagranite and felsic pegmatite. Pseudosection analysis of charnockite in the system NCKFMASHTO, supported by geothermometry of mafic orthogneiss, was used to infer peak metamorphic temperatures of 750–850 °C, approximately 150 °C lower than those estimated for metasedimentary gneisses from Rundvågshetta, 6 km to the northeast. SHRIMP U-Pb analysis of zircons from feldspar-pyroxene gneiss, which corresponds to a partially molten patch around mafic orthogneiss, yielded a Concordia upper intercept ages of 2507.9 ± 7.4 Ma, corresponding to the time of formation of the magmatic protolith to the orthogneiss. Partial melting during peak metamorphism probably took place between 591 and 548 Ma, as recorded in rims overgrew around magmatic zircon. Our results suggest that Rundvågshetta-Vesleknausen-Strandnibba region in southwestern Lützow-Holm Bay, where orthogneisses are dominant, consists of a single crustal block, possibly formed by ca. 2.5 Ga arc magmatism. The Neoarchean magmatic terrane was tectonically mingled with other fragments (such as metasedimentary units in northern Lützow-Holm Bay by subduction/collision events during the assembly of Gondwana supercontinent, and subsequently underwent ∼850 °C granulite-facies metamorphosed during Neoproterozoic to Cambrian final collisional event.

  5. Analysis of lithofacies, petrology/petrography, and porosity/permeability of the lower green river formation: Willow Creek

    Energy Technology Data Exchange (ETDEWEB)

    Morris, T.H., Garner, A.

    1994-04-14

    The 849.16 meter stratigraphic section was measured during consecutive spring field seasons. This section represents the ``lower`` Green River Formation which on the southwest flank of the basin rests stratigraphically above the dominant red beds of the Colton Member of the Green River Formation. The transition from Colton rocks to Green River rocks is gradual in the study area. Petrographic classification and textural analysis has been completed on 33 thin sections. These thin sections represent the volummetric majority of rock types in the measured section as well as few less common but very interesting lithofacies. Core plugs were taken from every lithology that was petrologically analyzed. Permeabilities were analyzed using a pressure transducer in a Hassler sleeve. Porosities from the lab were compared to point count porosities. In general there was good agreement and where there is some disagreement an explanation is given in the petrologic description. It appears that the sandstone lithofacies have much greater interparticle porosity. This is important to the study because these sandstones likely have greater hydrocarbon storage capacity than do the carbonate rocks. The data from this report have not been fully interpreted. There are several items relative to deposition facies interpretations and reservoir quality studies that are not as yet accomplished.

  6. Petrologic and isotopic data from the Cretaceous (Campanian) Blackhawk Formation and Star Point Sandstone (Mesaverde Group), Wasatch Plateau, Utah

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    Fishman, Neil S.; Turner, Christine E.; Peterson, Fred

    2013-01-01

    The presence of discrete minerals associated with coal—whether (1) detrital or authigenic constituents of the coals or in thin mudstone or siltstone units interbedded with coals, or (2) authigenic phases that formed along cleats—might influence its utilization as an energy resource. The build-up of sintered ash deposits on the surfaces of heat exchangers in coal-fired power plants, due to the alteration of minerals during combustion of the coal, can seriously affect the functioning of the boiler and enhance corrosion of combustion equipment. In particular, the presence of sodium in coals has been considered a key factor in the fouling of boilers; however, other elements (such as calcium or magnesium) and the amount of discrete minerals burned with coal can also play a significant role in the inefficiency of and damage to boilers. Previous studies of the quality of coals in the Cretaceous (Campanian) Blackhawk Formation of the Wasatch Plateau, Utah, revealed that the sodium content of the coals varied across the region. To better understand the origin and distribution of sodium in these coals, petrologic studies were undertaken within a sedimentological framework to evaluate the timing and geochemical constraints on the emplacement of sodium-bearing minerals, particularly analcime, which previously had been identified in coals in the Blackhawk Formation. Further, the study was broadened to include not just coals in the Blackhawk Formation from various localities across the Wasatch Plateau, but also sandstones interbedded with the coals as well as sandstones in the underlying Star Point Sandstone. The alteration history of the sandstones in both formations was considered a key component of this study because it records the nature and timing of fluids passing through them and the associated precipitation of sodium-bearing minerals; thus, the alteration history could place constraints on the distribution and timing of sodium mineralization in the interbedded or

  7. Petrology and phase equilibrium modeling of sapphirine + quartz assemblage from the Napier Complex, East Antarctica: Diagnostic evidence for Neoarchean ultrahigh-temperature metamorphism

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    Hisako Shimizu

    2013-11-01

    Full Text Available A synthesis of the petrological characters of granulite facies rocks that contain equilibrium sapphirine + quartz assemblage from two localities (Tonagh Island (TI and Priestley Peak (PP in the Napier Complex, East Antarctica, provides unequivocal evidence for extreme crustal metamorphism possibly associated with the collisional orogeny during Neoarchean. The reaction microstructures associated with sapphirine + quartz vary among the samples, probably suggesting different tectonic conditions during the metamorphic evolution. Sapphirine and quartz in TI sample were probably in equilibrium at the peak stage, but now separated by corona of Grt + Sil + Opx suggesting near isobaric cooling after the peak metamorphism, whereas the Spr + Qtz + Sil + Crd + Spl assemblage replaces garnet in PP sample suggesting post-peak decompression. The application of mineral equilibrium modeling in NCKFMASHTO system demonstrated that Spr + Qtz stability is lowered down to 930 °C due to small Fe3+ contents in the rocks (mole Fe2O3/(FeO + Fe2O3 = 0.02. The TI sample yields a peak p-T range of 950–1100 °C and 7.5–11 kbar, followed by cooling toward a retrograde stage of 800–950 °C and 8–10 kbar, possibly along a counterclockwise p-T path. In contrast, the peak condition of the PP sample shows 1000–1050 °C and >12 kbar, which was followed by the formation of Spr + Qtz corona around garnet at 930–970 °C and 6.7–7.7 kbar, suggesting decompression possibly along a clockwise p-T trajectory. Such contrasting p-T paths are consistent with a recent model on the structural framework of the Napier Complex that correlates the two areas to different crustal blocks. The different p-T paths obtained from the two localities might reflect the difference in the tectonic framework of these rocks within a complex Neoarchean subduction/collision belt.

  8. Origin of dolomitic rocks in the lower Permian Fengcheng formation, Junggar Basin, China: evidence from petrology and geochemistry

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    Zhu, Shifa; Qin, Yi; Liu, Xin; Wei, Chengjie; Zhu, Xiaomin; Zhang, Wei

    2016-09-01

    Although dolomitization of calcite minerals and carbonatization of volcanic rocks have been studied widely, the extensive dolomitic rocks that originated from altered volcanic and volcaniclastic rocks have not been reported. The dolomitic rocks of the Fengcheng Formation in the Junggar Basin of China appear to be formed under unusual geologic conditions. The petrological and geochemical characteristics indicate that the dolomitizing host rock is devitrified volcanic tuff. After low-temperature alteration and calcitization, these tuffaceous rocks are replaced by Mg-rich brine to form massive dolomitic tuffs. We propose that the briny (with -2 ‰ ~ 6 ‰ of δ13CPDB and -5 ‰ ~ 4 ‰ of δ18OPDB) and Mg-rich marine formation water (with 0.7060 ~ 0.7087 of 87Sr/86Sr ratio), the thick and intermediate-mafic volcanic ashes, and the tectonically compressional movement may have favored the formation of the unusual dolomitic rocks. We conclude that the proposed origin of the dolomitic rocks can be extrapolated to other similar terranes with volcaniclastic rocks, seabed tuffaceous sediment, and fracture filling of sill.

  9. METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    20160203 Ji Genyuan(Cores and Samples Center of Land Resources,Sanhe 065201,China);Dai Tagen Petrological Characteristics and Original Rocks for Metamorphic Rocks from the Jinmo Sb Deposit,in Quang Ninh Province,Vietnam(Acta Geologica Sichuan,ISSN1006-0995,CN51-1273/P,35(1),2015,p.43-46,6illus.,1table,6refs.)

  10. Carbonate petrology of algal limestones (Lois-Ciguera Formation, Upper Carboniferous, León, Spain)

    NARCIS (Netherlands)

    Meijer, de J.J.

    1971-01-01

    The Lois-Ciguera Formation is a unit of alternating limestones and terrigenous sediments of Lower to Upper Moscovian age in the Cantabrian Mountains of northern Spain. The proportion of limestones is fairly high, 30 to 50% of the total thickness. In the eastern part of the Lois-Ciguera Synclinorium,

  11. Petrology and tectonics of Phanerozoic continent formation: From island arcs to accretion and continental arc magmatism

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    Lee, C.-T.A.; Morton, D.M.; Kistler, R.W.; Baird, A.K.

    2007-01-01

    Mesozoic continental arcs in the North American Cordillera were examined here to establish a baseline model for Phanerozoic continent formation. We combine new trace-element data on lower crustal xenoliths from the Mesozoic Sierra Nevada Batholith with an extensive grid-based geochemical map of the Peninsular Ranges Batholith, the southern equivalent of the Sierras. Collectively, these observations give a three-dimensional view of the crust, which permits the petrogenesis and tectonics of Phanerozoic crust formation to be linked in space and time. Subduction of the Farallon plate beneath North America during the Triassic to early Cretaceous was characterized by trench retreat and slab rollback because old and cold oceanic lithosphere was being subducted. This generated an extensional subduction zone, which created fringing island arcs just off the Paleozoic continental margin. However, as the age of the Farallon plate at the time of subduction decreased, the extensional environment waned, allowing the fringing island arc to accrete onto the continental margin. With continued subduction, a continental arc was born and a progressively more compressional environment developed as the age of subducting slab continued to young. Refinement into a felsic crust occurred after accretion, that is, during the continental arc stage, wherein a thickened crustal and lithospheric column permitted a longer differentiation column. New basaltic arc magmas underplate and intrude the accreted terrane, suture, and former continental margin. Interaction of these basaltic magmas with pre-existing crust and lithospheric mantle created garnet pyroxenitic mafic cumulates by fractional crystallization at depth as well as gabbroic and garnet pyroxenitic restites at shallower levels by melting of pre-existing lower crust. The complementary felsic plutons formed by these deep-seated differentiation processes rose into the upper crust, stitching together the accreted terrane, suture and former

  12. The Amaranth Formation of the Williston Basin: Paleomagnetic, Petrologic and Geochemical studies

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    Szabo, E.; Cioppa, M. T.; Al-Aasm, I.

    2008-12-01

    Major debate continues to exist concerning the time of deposition of the Amaranth Formation in the Williston Basin of North America, with postulated ages of Pennsylvanian, Permian, Triassic, Lower and Middle Jurassic. A multidisciplinary study of the lower member of the Amaranth Formation was conducted in six wells in Manitoba. The lower Amaranth red beds are composed of red carbonate-rich and carbonate-poor interbedded sandstones/siltstones/shales containing dolomite and anhydrite and lacking diagnostic fossils. Preliminary analysis of the oxygen and carbon isotope values measured for replacive and cement dolomite show variations related to particular lithologies that can be correlated to the types of dolomite present in the rocks. The siliciclastic sections are dominated by detrital, zoned dolomite that has recrystallized rims, whereas in the more carbonate-rich and evaporitic samples with little to no clastic content, replacive matrix dolomite is the dominant phase. Dolomite samples from the siliciclastic sections are characterized by relatively depleted carbon and oxygen isotope values, the dolomite matrix samples have relatively enriched oxygen and carbon isotope values and a few samples containing replacement matrix dolomite with minor clastic input have intermediate isotope values. These variations reflect primary and diagenetic overprints. Hematite is the major magnetization carrier, with occasional softer magnetic minerals such as magnetite. Optical microscopy revealed the existence of two types of hematite: detrital specular hematite and very fine red pigment hematite. The paleomagnetic data reveals at least three episodes of magnetization. The most pervasive magnetization, B, was formed during the Permian-Carboniferous Kiaman Reverse Superchron. An isolated magnetization in a couple of wells, C, suggests a remagnetization event that happened sometime between mid-Jurassic and Neogene, possibly resulting from a localized oxidizing fluid flow event. The

  13. Petrology and geochemistry of Cenozoic intra-plate basalts in east-central China: Constraints on recycling of an oceanic slab in the source region

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    Li, Yan-Qing; Ma, Chang-Qian; Robinson, Paul T.

    2016-10-01

    Cenozoic mafic rocks in Jiangsu and Anhui Provinces, east-central China are chiefly basanites and alkali olivine basalts with subordinate tholeiites, which were erupted in three stages; Paleogene, Neogene and Quaternary. The rocks become increasingly alkaline as they become younger. On a primitive mantle-normalized multi-element plot, these lavas exhibit typical OIB-like trace element patterns, including enrichment in most incompatible elements (LILE and HFSE) and negative K and Pb anomalies. The compositions of the mafic rocks indicate that they were derived from a mantle source mainly containing clinopyroxene and garnet, most probably a mixture of pyroxenite/eclogite and peridotite. A mineral equilibrium projection shows that all the mafic magmas were produced at pressures of 3-4 GPa, implying an asthenospheric origin. Their positive Ba and Sr anomalies and relatively high 87Sr/86Sr ratios suggest derivation from an EM1-type mantle source. However, poor correlations between 87Sr/86Sr and 143Nd/144Nd indicate an isotopically heterogeneous source for the magmas, including DMM, EM1 and EM2, representing mantle peridotite, recycled ancient oceanic crust and seafloor sedimentary rocks, respectively. Variable correlations between 87Sr/86Sr and 143Nd/144Nd ratios, CaO-MgO contents and Eu/Eu* and Ce/Ce* anomalies with rock type imply that marine sediments (plus variable amounts of oceanic crust) and peridotites were the dominant source lithologies of the basanites, whereas recycled oceanic crust (pyroxenite/eclogite) was the main source of the weakly alkaline basalts. This hypothesis is supported by seismic tomographic images of the mantle beneath the region, which show the presence of a stagnant subducted slab in the mantle transition zone. Thus, we propose a petrological model in which a hybrid magma column originated from the mantle transition zone and assimilated some of the overlying peridotite during upwelling, to become the parental magmas of these mafic rocks

  14. Paleoproterozoic crustal evolution in the East Sarmatian Orogen: Petrology, geochemistry, Sr-Nd isotopes and zircon U-Pb geochronology of andesites from the Voronezh massif, Western Russia

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    Terentiev, R. A.; Savko, K. A.; Santosh, M.

    2016-03-01

    Andesites and related plutonic rocks are major contributors to continental growth and provide insights into the interaction between the mantle and crust. Paleoproterozoic volcanic rocks are important components of the East Sarmatian Orogen (ESO) belonging to the East European Craton, although their petrogenesis and tectonic setting remain controversial. Here we present petrology, mineral chemistry, bulk chemistry, Sr-Nd isotopes, and zircon U-Pb geochronological data from andesites and related rocks in the Losevo and Vorontsovka blocks of the ESO. Clinopyroxene phenocrysts in the andesites are depleted in LREE, and enriched in HFSE (Th, Nb, Zr, Hf, Ti) and LILE (Ba, Sr). Based on the chemistry of pyroxenes and whole rocks, as well as Fe-Ti oxides, we estimate a temperature range of 1179 to 1262 °C, pressures of 11.3 to 13.0 kbar, H2O content of 1-5 wt.%, and oxygen fu gacity close to the MH buffer for the melts of the Kalach graben (KG) and the Baygora area (BA) andesites. Our zircon U-Pb geochronological data indicate new zircon growth during the middle Paleoproterozoic as displayed by weighted mean 207Pb/206Pb ages of 2047 ± 17 Ma and 2040 ± 16 Ma for andesite and dacite-porphyry of the BA, and 2050 ± 16 Ma from high-Mg basaltic andesite of the KG. The andesites and related rocks of the KG and BA are characterized by high magnesium contents (Mg # up to 0.68). All these volcanic rocks are depleted in LREE and HFSE, and display negative Nb and Ti anomalies relative to primitive mantle. The high-Mg bulk composition, and the presence of clinopyroxene phenocrysts suggests that the parent melts of the KG and BA suite were in equilibrium with the mantle rocks. The rocks show positive εNd(T) values and low initial 87Sr/86Sr, suggesting that the magmas were mostly derived from metasomatized mantle source. The geochemical differences between the two andesite types are attributed to: the predominance of fractional crystallization, and minor role of contamination in the

  15. Petrology and geochemistry of intrusive body of iron deposit of Sarab-3, east of Takab-north west of Iran

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    Mohammad Maanijou

    2016-09-01

    Full Text Available The Sarab-3 intrusive bodyis located in the NW of Iran, in Sanandaj-Sirjan zone and in the east of Takab city. Based on field observations as well as petrographic features, the lithologic composition of intrusion (Miocene age ranges within the diorite-leucodiorite, monzodiorite, quartz monzodiorite, granodiorite and granite. In terms of geochemical characteristics, the rocks studied, are I-type, with calc-alkaline affinity and meta-aluminous character. Enrichment of LILE (K, U, Sr, Ce, Th, Pb, Ba and LREE relative to HFSE (Zr, Y, Ti, P, Nb and HREE, low Ce / Pb and Nb / U ratios and high Ba / Nb reveal that the rocks under study were originated in an active continental margin subduction-related tectonic setting. The negative anomalies of Ti, Nb and P on the spider diagram also confirm this fact. Low ratios of (Na2O + K2O / (FeOt + MgO + TiO2 and (Al2O3 / FeOt + MgO + TiO2 along with low Rb/Sr concentration (< 0.6 propose that the Sarab-3 intrusive rock is derived from a meta-basaltic source.

  16. Petrology of Anomalous Eucrites

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    Mittlefehldt, D. W.; Peng, Z. X.; Ross, D. K.

    2015-01-01

    Most mafic achondrites can be broadly categorized as being "eucritic", that is, they are composed of a ferroan low-Ca clinopyroxene, high-Ca plagioclase and a silica phase. They are petrologically distinct from angritic basalts, which are composed of high-Ca, Al-Ti-rich clinopyroxene, Carich olivine, nearly pure anorthite and kirschsteinite, or from what might be called brachinitic basalts, which are composed of ferroan orthopyroxene and high-Ca clinopyroxene, intermediate-Ca plagioclase and ferroan olivine. Because of their similar mineralogy and composition, eucrite-like mafic achondrites formed on compositionally similar asteroids under similar conditions of temperature, pressure and oxygen fugacity. Some of them have distinctive isotopic compositions and petrologic characteristics that demonstrate formation on asteroids different from the parent of the HED clan (e.g., Ibitira, Northwest Africa (NWA) 011). Others show smaller oxygen isotopic distinctions but are otherwise petrologically and compositionally indistinguishable from basaltic eucrites (e.g., Pasamonte, Pecora Escarpment (PCA) 91007). The degree of uniformity in delta O-17 of eucrites and diogenites is one piece of evidence considered to favor of a magma-ocean scenario for their petrogenesis. Given that the O isotopic differences separating Pasamonte and PCA 91007 from other eucrites are small, and that there is an absence of other distinguishing characteristics, a legitimate question is: Did the HED parent asteroid fail to homogenize via a magma-ocean stage, thus explaining outliers like Pasamonte? We are initiating a program of study of anomalous eucrite-like achondrites as one part of our effort to seek a resolution of this issue. Here we present preliminary petrologic information on Asuka (A-) 881394, Elephant Moraine (EET) 87520 and EET 87542. We will have studied several more by conference time.

  17. Organic petrology of Paleocene Marcelina Formation coals, Paso Diablo mine, western Venezuela: Tectonic controls on coal type

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    Hackley, P.C.; Martinez, M.

    2007-01-01

    About 7??Mt of high volatile bituminous coal are produced annually from the four coal zones of the Upper Paleocene Marcelina Formation at the Paso Diablo open-pit mine of western Venezuela. As part of an ongoing coal quality study, we have characterized twenty-two coal channel samples from the mine using organic petrology techniques. Samples also were analyzed for proximate-ultimate parameters, forms of sulfur, free swelling index, ash fusion temperatures, and calorific value. Six of the samples represent incremental benches across the 12-13??m thick No. 4 bed, the stratigraphically lowest mined coal, which is also mined at the 10??km distant Mina Norte open-pit. Organic content of the No. 4 bed indicates an upward increase of woody vegetation and/or greater preservation of organic material throughout the life of the original mire(s). An upward increase in telovitrinite and corresponding decrease in detrovitrinite and inertinite illustrate this trend. In contrast, stratigraphically higher coal groups generally exhibit a 'dulling upward' trend. The generally high inertinite content, and low ash yield and sulfur content, suggest that the Paso Diablo coals were deposited in rain-fed raised mires, protected from clastic input and subjected to frequent oxidation and/or moisture stress. However, the two thinnest coal beds (both 0.7??m thick) are each characterized by lower inertinite and higher telovitrinite content relative to the rest of Paso Diablo coal beds, indicative of less well-established raised mire environments prior to drowning. Foreland basin Paleocene coals of western Venezuela, including the Paso Diablo deposit and time-correlative coal deposits of the Ta??chira and Me??rida Andes, are characterized by high inertinite and consistently lower ash and sulfur relative to Eocene and younger coals of the area. We interpret these age-delimited coal quality characteristics to be due to water availability as a function of the tectonic control of subsidence rate. It

  18. Neoproterozoic eclogite- to high-pressure granulite-facies metamorphism in the Mozambique belt of east-central Tanzania: A petrological, geochemical and geochronological approach

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    Sommer, H.; Kröner, A.; Lowry, J.

    2017-07-01

    This study investigated Neoproterozoic (Pan-African) eclogite- and high-pressure-granulite (E-HPG) facies rocks from the Mozambique belt of east-central Tanzania, collected close to the town of Ifakara and the adjacent Furua area from different tectonic settings, the Palaeoproterozoic Usagaran and the Neoproterozoic Mozambique belt. The studied rocks are E-HPG facies granite- and diorite-gneisses and a meta-gabbroic rock, which are retrogressed to amphibolite- and greenschist-facies conditions. Four different clockwise P-T paths were constructed. The first P-T path for a granodioritic gneiss displays peak metamorphic conditions at 830 °C and 13.0 kbar. The second P-T path for a quartz dioritic gneiss shows peak metamorphic conditions of 920 °C and 14.9 kbar. The third P-T path for a mafic granulite shows peak metamorphic conditions of 820 °C and 13.2 kbar. A fourth P-T path for a monzodioritic gneiss also displays peak metamorphic conditions of up to 810 °C and 14.9 kbar. Evidence for all four P-T paths is provided by mineral chemical and modal abundance calculations in combination with textural observations in thin sections. Zircon ages indicate that the east-central part of the Mozambique belt in Tanzania consists of granite-, granodiorite- and monzodiorite gneisses with Mesoarchaean ( 2915 Ma), Neoarchaean ( 2637-2676 Ma) and Palaeoproterozoic ( 1873-1926 Ma) protolith ages. Early Neoproterozoic (Tonian) igneous zircons were found in the mafic granulite with an age of 989 Ma. Late Neoproterozoic (Cyrogenian) igneous zircons were found in a dioritic and monzodiorite gneiss with ages of 748 Ma and 718 Ma, respectively. Metamorphic zircons extracted from Qtz-monzodiorite and granodiorite gneisses yielded ages of 640 Ma and are considered to approximate the peak of regional E-HPG metamorphism. We suggest that this high-grade metamorphic event was caused by the collision of fragments of East and West Gondwana during the Pan-African orogeny, associated with ocean

  19. METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20132334 Chai Fengmei(Key Laboratory of Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt,Xinjiang University,Urumqi 830049,China);Yang Fuquan Geochronology and Genesis of Meta-Felsic Volcanic Rocks from the Kangbutiebao Formation in Chonghuer Basin on Southern Margin of Altay,Xinjiang(Geological

  20. SEDIMENTARY PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091542 Cai Xiyao(West Branch,Research Institute of Petroleum Exploration and Development,SINOPEC,Urumqi 830011,China);Wu Yasheng Paleoecology of Middle-Upper Ordovician Reefal Community in Bachu,Xinjiang,Northwestern China(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,82(8),2008,p.1046-1051,1161,4 illus.,1 table,1 plate,18 refs.)Key words:reefs,XinjiangAt the Lianglitage Mountain in the eastern Bachu area,Xinjiang outcrops the Lianglitage reefs(Yijianfang Formation)of Middle Ordovician and Kaidi reefs(mid Lianglitage Formation)of Upper Ordovician.The former has echinoderm banks reef-frame builders,which consists of receptaculitids and formed typical framestone.Primary porosities widely developed at the centre of receptaculitids,

  1. METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110122 Cai Zhihui(Key Laboratory of Continental Dynamics of the Ministry of Land and Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China);Li Huaqi The Formation Mechanism of Garnet Porphyroblast with Snowball Structure:A Case Study from the Quartz Schist in West Indus-Yarlung Tsangpo Suture Zone,Namche Barwa,Tibet(Earth Science Frontiers,ISSN1005-2321,CN11-3370/P,17(1),2010,p.61-73,13 illus.,33 refs.)Key words:suture zones,TibetThe quartz schist from Mil

  2. IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110832 Cui Yurong(School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China);Xie Zhi SHRIMP U-Pb Dating of Zircons from the Late Mesozoic Basalts in Eastern Zhejiang Province and Its Geological Significance(Geological Journal of China Universities,ISSN1006-7493,CN32-1440/P,16(2),2010,p.198-212,5 illus.,1 table,39 refs.)Key words:basalts,U-Pb dating,Zhejiang Province The zircon U-Pb ages were dated by SHRIMP method for eight basaltic rocks occurred in the eastern area of Zhejiang Province,which were erupted during the Late Mesozoic and named as Lower and Upper rock series(LRS&URS). The data suggest that the zircons from both rock series are of magmatic origin and represent the formation times of the basalts of LRS and URS.Thus,it can be concluded that the formation time of the URS and LRS is

  3. Petrology, geochemistry and zircon U-Pb geochronology of a layered igneous complex from Akarui Point in the Lützow-Holm Complex, East Antarctica: Implications for Antarctica-Sri Lanka correlation

    Science.gov (United States)

    Kazami, Sou; Tsunogae, Toshiaki; Santosh, M.; Tsutsumi, Yukiyasu; Takamura, Yusuke

    2016-11-01

    The Lützow-Holm Complex (LHC) of East Antarctica forms part of a complex subduction-collision orogen related to the amalgamation of the Neoproterozoic supercontinent Gondwana. Here we report new petrological, geochemical, and geochronological data from a metamorphosed and disrupted layered igneous complex from Akarui Point in the LHC which provide new insights into the evolution of the complex. The complex is composed of mafic orthogneiss (edenite/pargasite + plagioclase ± clinopyroxene ± orthopyroxene ± spinel ± sapphirine ± K-feldspar), meta-ultramafic rock (pargasite + olivine + spinel + orthopyroxene), and felsic orthogneiss (plagioclase + quartz + pargasite + biotite ± garnet). The rocks show obvious compositional layering reflecting the chemical variation possibly through magmatic differentiation. The metamorphic conditions of the rocks were estimated using hornblende-plagioclase geothermometry which yielded temperatures of 720-840 °C. The geochemical data of the orthogneisses indicate fractional crystallization possibly related to differentiation within a magma chamber. Most of the mafic-ultramafic samples show enrichment of LILE, negative Nb, Ta, P and Ti anomalies, and constant HFSE contents in primitive-mantle normalized trace element plots suggesting volcanic arc affinity probably related to subduction. The enrichment of LREE and flat HREE patterns in chondrite-normalized REE plot, with the Nb-Zr-Y, Y-La-Nb, and Th/Yb-Nb/Yb plots also suggest volcanic arc affinity. The felsic orthogneiss plotted on Nb/Zr-Zr diagram (low Nb/Zr ratio) and spider diagrams (enrichment of LILE, negative Nb, Ta, P and Ti anomalies) also show magmatic arc origin. The morphology, internal structure, and high Th/U ratio of zircon grains in felsic orthogneiss are consistent with magmatic origin for most of these grains. Zircon U-Pb analyses suggest Early Neoproterozoic (847.4 ± 8.0 Ma) magmatism and protolith formation. Some older grains (1026-882 Ma) are regarded as

  4. Petrology, magnetostratigraphy and geochronology of the Miocene volcaniclastic Tepoztlán Formation: implications for the initiation of the Transmexican Volcanic Belt (Central Mexico)

    Science.gov (United States)

    Lenhardt, Nils; Böhnel, Harald; Wemmer, Klaus; Torres-Alvarado, Ignacio S.; Hornung, Jens; Hinderer, Matthias

    2010-09-01

    The volcaniclastic Tepoztlán Formation (TF) represents an important rock record to unravel the early evolution of the Transmexican Volcanic Belt (TMVB). Here, a depositional model together with a chronostratigraphy of this Formation is presented, based on detailed field observations together with new geochronological, paleomagnetic, and petrological data. The TF consists predominantly of deposits from pyroclastic density currents and extensive epiclastic products such as tuffaceous sandstones, conglomerates and breccias, originating from fluvial and mass flow processes, respectively. Within these sediments fall deposits and lavas are sparsely intercalated. The clastic material is almost exclusively of volcanic origin, ranging in composition from andesite to rhyolite. Thick gravity-driven deposits and large-scale alluvial fan environments document the buildup of steep volcanic edifices. K-Ar and Ar-Ar dates, in addition to eight magnetostratigraphic sections and lithological correlations served to construct a chronostratigraphy for the entire Tepoztlán Formation. Correlation of the 577 m composite magnetostratigraphic section with the Cande and Kent (1995) Geomagnetic Polarity Time Scale (GPTS) suggests that this section represents the time intervall 22.8-18.8 Ma (6Bn.1n-5Er; Aquitanian-Burdigalian, Lower Miocene). This correlation implies a deposition of the TF predating the extensive effusive activity in the TMVB at 12 Ma and is therefore interpreted to represent its initial phase with predominantly explosive activity. Additionally, three subdivisions of the TF were established, according to the dominant mode of deposition: (1) the fluvial dominated Malinalco Member (22.8-22.2 Ma), (2) the volcanic dominated San Andrés Member (22.2-21.3 Ma) and (3) the mass flow dominated Tepozteco Member (21.3-18.8 Ma).

  5. Sedimentology, petrology, and gas potential of the Brallier Formation: upper Devonian turbidite facies of the Central and Southern Appalachians

    Energy Technology Data Exchange (ETDEWEB)

    Lundegard, P.D.; Samuels, N.D.; Pryor, W.A.

    1980-03-01

    The Upper Devonian Brallier Formation of the central and southern Appalachian basin is a regressive sequence of siltstone turbidites interbedded with mudstones, claystones, and shales. It reaches 1000 meters in thickness and overlies basinal mudrocks and underlies deltaic sandstones and mudrocks. Facies and paleocurrent analyses indicate differences between the depositional system of the Brallier Formation and those of modern submarine fans and ancient Alpine flysch-type sequences. The Brallier system is of finer grain size and lower flow intensity. In addition, the stratigraphic transition from turbidites to deltaic sediments is gradual and differs in its facies succession from the deposits of the proximal parts of modern submarine fans. Such features as massive and pebbly sandstones, conglomerates, debris flows, and massive slump structures are absent from this transition. Paleocurrents are uniformly to the west at right angles to basin isopach, which is atypical of ancient turbidite systems. This suggests that turbidity currents had multiple point sources. The petrography and paleocurrents of the Brallier Formation indicate an eastern source of sedimentary and low-grade metasedimentary rocks with modern relief and rainfall. The depositional system of the Brallier Formation is interpreted as a series of small ephemeral turbidite lobes of low flow intensity which coalesced in time to produce a laterally extensive wedge. The lobes were fed by deltas rather than submarine canyons or upper fan channel systems. This study shows that the present-day turbidite facies model, based mainly on modern submarine fans and ancient Alpine flysch-type sequences, does not adequately describe prodeltaic turbidite systems such as the Brallier Formation. Thickly bedded siltstone bundles are common features of the Brallier Formation and are probably its best gas reservoir facies, especially when fracture porosity is well developed.

  6. Important role of magma mixing in generating the Mesozoic monzodioritic-granodioritic intrusions related to Cu mineralization, Tongling, East China: Evidence from petrological and in situ Sr-Hf isotopic data

    Science.gov (United States)

    Chen, C. J.; Chen, B.; Li, Z.; Wang, Z. Q.

    2016-04-01

    The Mesozoic ore-bearing high-Mg monzodioritic-granodioritic rocks in the Tongling mining district (East China) have been described as having adakitic affinities, and their origin has been attributed to partial melting of delaminated eclogite at depth in the mantle, followed by interaction of the resultant granitic magma with mantle peridotite. Here we present petrological data and in situ Sr isotopic data for zoned plagioclase that are inconsistent with the eclogite-derived model and instead propose a model that involves magma mixing of siliceous crustal melts and basaltic magma that was derived from metasomatized mantle in a back-arc extensional regime. The principal geochemical signatures of these Mesozoic rocks include a high-K calc-alkaline affinity, high values of Mg#, high Sr-Ba abundances, high Sr/Y and La/Yb ratios, εNd(t) = - 13.1 to - 9.0, and ISr = 0.70707-0.70824. The magma mixing model is supported by (1) the common existence of mafic microgranular enclaves (MMEs) and the disequilibrium textures of plagioclase and amphibole, (2) the 87Sr/86Sr ratios of embayed high-Ca cores of plagioclase that are distinctly lower than in the euhedral low-Ca overgrowth rims, (3) the negative correlations between whole-rock Nd and Sr isotopic ratios, and (4) the significant differences in the values of εHf(t) (- 9.5 to - 26) within different zircons from the same intrusion.

  7. Towards modern petrological collections

    NARCIS (Netherlands)

    Kriegsman, L.M.

    2004-01-01

    Petrological collections result from sampling for academic research, for aesthetic or commercial reasons, and to document natural diversity. Selection criteria for reducing and enhancing collections include adequate documentation, potential for future use, information density, time and money investe

  8. The Petrology and Diagenetic History of the Phacoides Sandstone, Temblor Formation at the McKittrick Oil Field, California

    Science.gov (United States)

    Kaess, A. B.; Horton, R. A.

    2015-12-01

    The McKittrick oil field is located near the western edge of the San Joaquin Basin, California. The oil field is currently in production with 480 wells producing from the Tulare, San Joaquin, Reef Ridge, Monterey, Temblor, Tumey, and Kreyenhagen formations. Within the Temblor Formation production is mainly from the Miocene Carneros and the Phacoides sandstones. Eighty-two samples from the Phacoides sandstone (2403 - 3045 m below surface) were obtained from the California Well Sample Repository to characterize and understand the diagenetic history and its influence on its reservoir properties. Petrographic thin sections were analyzed by quantitative optical petrography, energy dispersive X-ray spectrometry, and imaging with back-scatter electron and cathodoluminescence. The Phacoides sandstone consists of fine to very coarse, poorly to well-sorted, arkosic arenites, and wackes with detrital framework grains including sub-angular quartz, K-feldspar (microcline and orthoclase), plagioclase, and lithic fragments. Ba-free, Ba-rich, and perthitic K-feldspars are present. Accessory minerals include glauconite, biotite, muscovite, magnetite, titanomagnetite, sphene, zircon, apatite, corundum, and rutile. Diagenetic alteration includes: (1) compaction, (2) mineral dissolution, (3) albitization of feldspars, alteration of biotite to pyrite and chlorite, replacement of framework grains by calcite, (4) alteration of volcanic rock fragments, (5) cementation by kaolinite, calcite and dolomite, and (6) precipitation of K-feldspar and quartz overgrowths. Early-formed fractures were healed by authigenic quartz, albite, and K-feldspars. Precipitation of carbonates and clays, rearranging of broken grains, and formation of pseudomatrix reduced primary porosity. Secondary porosity is common and formed initially by the dissolution of plagioclase (excluding albite) and volcanic fragments, and later by dissolution of calcite, dolomite, and detrital K-feldspars. Hydrocarbon emplacement was

  9. Regional conflict formations: is the Middle East next?

    NARCIS (Netherlands)

    Leenders, R.

    2007-01-01

    As Iraq is plunging into civil war, politics and violence in the Middle East are increasingly perceived to be highly interconnected and entwined. This article offers an attempt to understand the nature and scope of this regional interconnectedness involving three of the region's states—Iraq, Syria

  10. Organic petrology and geochemistry of mudrocks from the lacustrine Lucaogou Formation, Santanghu Basin, northwest China: Application to lake basin evolution

    Science.gov (United States)

    Hackley, Paul C.; Fishman, Neil; Wu, Tao; Baugher, Gregory

    2016-01-01

    Exploration for tight oil in the frontier Santanghu Basin of northwest China has resulted in recent commercial discoveries sourced from the lacustrine Upper Permian Lucaogou Formation, already considered a “world class source rock” in the Junggar Basin to the west. Here we apply an integrated analytical program to carbonate-dominated mudrocks from the Lucaogou Formation in Santanghu Basin to document the nature of organic matter (OM) in the context of an evolving lake system. The organic-rich samples (TOC 2.8–11.4 wt%; n = 10) were widely spaced from an ~ 200 m cored section, interpreted from textural and mineralogical evidence to document transition from a lower under-filled to an overlying balanced-filled lake. Organic matter is dominated by moderate to strongly fluorescent amorphous material with Type I geochemical signature (HI values 510–755; n = 10) occurring in a continuum from lamellar stringers, 10–20 μm thick, some ≥ 1 mm in length (possible microbial mat; preserved only in lower under-filled section) to finely-disseminated amorphous groundmass intimately intermixed with mineral matrix. Biomarkers for methanotrophs and photosynthetic cyanobacteria indicate a complex microbial consortium. A unicellular prasinophyte green alga(?), similar to Tasmanites in marine rocks, is present as discrete flattened discs 50–100 μm in diameter. Type III OM including vitrinite (some fluorescent) and inertinite also is abundant. Solid bitumen, indicating local kerogen conversion, fills voids and occurs throughout the cored section. Vitrinite reflectance values are 0.47–0.58%, consistent with strong OM fluorescence but may be “suppressed”. Other proxies, e.g., biomarker parameters, indicate the Lucaogou Formation is in the early oil window at this location. On average, slightly more amorphous OM and telalginite are present in the lower section, consistent with a shallow, stratified, saline environment with low sediment dilution. More

  11. Hydrocarbon potential of Early Cretaceous lacustrine sediments from Bima Formation, Yola Sub-basin, Northern Benue Trough, NE Nigeria: Insight from organic geochemistry and petrology

    Science.gov (United States)

    Sarki Yandoka, Babangida M.; Abdullah, Wan Hasiah; Abubakar, M. B.; Adegoke, Adebanji Kayode; Maigari, A. S.; Haruna, A. I.; Yaro, Usman Y.

    2017-05-01

    The Early Cretaceous lacustrine sediments from Bima Formation in the Yola Sub-basin, Northern Benue Trough, northeastern Nigeria were studied based on organic geochemistry and petrology. This is in other to provide information on hydrocarbon generation potential; organic matter type (quality), richness (quantity), origin/source inputs, redox conditions (preservation) and thermal maturation in relation to thermal effect of Tertiary volcanics. The total organic carbon (TOC) contents ranges from 0.38 to 0.86 wt % with extractable organic matter (EOM) below 1000 ppm and pyrolysis S2 yield values from 0.16 to 0.68 mg/g, suggesting poor to fair source rock richness. Based on kerogen pyrolysis and microscopy coupled with biomarker parameters, the organic matters contain Type I (lacustrine algae), Type III (terrestrially derived land-plants) and Type IV kerogens deposited in a mixed lacustrine-terrestrial environment under suboxic to relatively anoxic conditions. This suggest potential occurrence of Early Cretaceous lacustrine sediments (perhaps Lower Cretaceous petroleum system) in Yola Sub-basin of the Northern Benue Trough as present in the neighbouring basins of Chad, Niger and Sudan Republics that have both oil and gas generation potential within the same rift trend (WCARS). Vitrinite reflectance (%Ro) and Tmax values of the lacustrine shales ranges from 1.12 to 2.32 VRo% and 448-501 °C, respectively, indicating peak-late to post-maturity stage. This is supported by the presence of dark brown palynomorphs, amorphous organic matter and phytoclasts as well as inertinite macerals. Consequently, the organic matters in the lacustrine shales of Bima Formation in the Yola Sub-basin appeared as a source of oil (most likely even waxy) and gas prone at a relatively deeper part of the basin. However, the high thermal maturity enhanced the organic matters and most of the hydrocarbons that formed in the course of thermal maturation were likely expelled to the reservoir rock units

  12. Neoarchean-Early Paleoproterozoic and Early Neoproterozoic arc magmatism in the Lützow-Holm Complex, East Antarctica: Insights from petrology, geochemistry, zircon U-Pb geochronology and Lu-Hf isotopes

    Science.gov (United States)

    Tsunogae, Toshiaki; Yang, Qiong-Yan; Santosh, M.

    2016-10-01

    The Lützow-Holm Complex (LHC) of East Antarctica forms part of the Neoproterozoic-Cambrian high-grade metamorphic segment of the East African-Antarctic Orogen. Here we present new petrological, geochemical, and zircon U-Pb and Lu-Hf isotopic data for meta-igneous rocks including charnockite, felsic gneiss, metagabbro, and mafic granulite from the LHC and evaluate the Neoarchean to Early Paleoproterozoic (ca. 2.5 Ga) and Early Neoproterozoic (ca. 1.0 Ga) arc magmatic events. The trace element geochemical signatures reveal a volcanic arc affinity for the charnockites from Sudare Rocks and Vesleknausen and felsic gneiss from Rundvågshetta, suggesting that the protoliths of these rocks were derived from felsic arc magmas. In contrast, metagabbros from Skallevikshalsen and Austhovde, occurring as boudins in metasediments, show non-arc signatures (within-plate basalt or mid-oceanic ridge basalt). The upper intercept ages of magmatic zircons in charnockite plotted on concordia diagrams yielded 2508 ± 14 Ma (Sudare Rocks) and 2490 ± 18 Ma (Vesleknausen), clearly suggesting a Neoarchean to Early Paleoproterozoic arc magmatic event. A subsequent thermal event during Early Neoproterozoic traced by 206Pb/238U age of oscillatory-zoned core of zircon in mafic granulite from Langhovde (973 ± 10 Ma) is consistent with a similar Early Neoproterozoic magmatic event reported from the LHC, suggesting a second stage of arc magmatism. The timing of peak metamorphism has been inferred from 206Pb/238U mean ages of structureless zircons in metagabbros from Skallevikshalsen and Austhovde, mafic granulite from Langhovde, and felsic gneiss from Rundvågshetta in the range of 551 ± 5.4 to 584 ± 5.0 Ma. Zircon Lu-Hf data of Neoarchean charnockites from Sudare Rocks and Vesleknausen indicate that the protolith magma was sourced from Paleo- to Neoarchean juvenile components mixed with reworked ancient crustal materials. Protolith magmatic rock of the felsic gneiss from Rundvågshetta might

  13. Petrology of arkosic sandstones, Pennsylvanian Minturn Formation and Pennsylvanian and Permian Sangre de Cristo Formation, Sangre de Cristo Range, Colorado - data and preliminary interpretations

    Science.gov (United States)

    Lindsey, D.A.

    2000-01-01

    This report describes the mineral and chemical composition of immature, arkosic sandstones of the Pennsylvanian Minturn and Pennsylvanian and Permian Sangre de Cristo Formations, which were derived from the Ancestral Rocky Mountains. Located in the Sangre de Cristo Range of southern Colorado, the Minturn and Sangre de Cristo Formations contain some of the most immature, sodic arkoses shed from the Ancestral Rocky Mountains. The Minturn Formation was deposited as fan deltas in marine and alluvial environments; the Sangre de Cristo Formation was deposited as alluvial fans. Arkoses of the Minturn and Sangre de Cristo Formations are matrix-rich and thus may be properly considered arkosic wackes in the terminology of Gilbert (Williams and others, 1954). In general, potassium feldspar and plagioclase are subequal in abundance. Arkose of the Sangre de Cristo Formation is consistently plagioclase-rich; arkose from the Minturn Formation is more variable. Quartz and feldspar grains are accompanied by a few percent rock fragments, consisting mostly of intermediate to granitic plutonic rocks, gneiss, and schist. All of the rock fragments seen in sandstone are present in interbedded conglomerate, consistent with derivation from a Precambrian terrane of gneiss and plutonic rocks much like that exposed in the present Sangre de Cristo Range. Comparison of mineral and major oxide abundances reveals a strong association of detrital quartz with SiO2, all other detrital minerals (totaled) with Al2O3, potassium feldspar plus mica with K2O, and plagioclase with Na2O. Thus, major oxide content is a good predictor of detrital mineralogy, although contributions from matrix and cement make these relationships less than perfect. Detrital minerals and major oxides tend to form inverse relationships that reflect mixtures of varying quantities of minerals; when one mineral is abundant, the abundance of others declines by dilution. In arkose of the Minturn and Sangre de Cristo Formations, the

  14. Petrology of arkosic sandstones, Pennsylvanian Minturn Formation and Pennsylvanian and Permian Sangre de Cristo Formation, Sangre de Cristo Range, Colorado - data and preliminary interpretations

    Science.gov (United States)

    Lindsey, D.A.

    2000-01-01

    This report describes the mineral and chemical composition of immature, arkosic sandstones of the Pennsylvanian Minturn and Pennsylvanian and Permian Sangre de Cristo Formations, which were derived from the Ancestral Rocky Mountains. Located in the Sangre de Cristo Range of southern Colorado, the Minturn and Sangre de Cristo Formations contain some of the most immature, sodic arkoses shed from the Ancestral Rocky Mountains. The Minturn Formation was deposited as fan deltas in marine and alluvial environments; the Sangre de Cristo Formation was deposited as alluvial fans. Arkoses of the Minturn and Sangre de Cristo Formations are matrix-rich and thus may be properly considered arkosic wackes in the terminology of Gilbert (Williams and others, 1954). In general, potassium feldspar and plagioclase are subequal in abundance. Arkose of the Sangre de Cristo Formation is consistently plagioclase-rich; arkose from the Minturn Formation is more variable. Quartz and feldspar grains are accompanied by a few percent rock fragments, consisting mostly of intermediate to granitic plutonic rocks, gneiss, and schist. All of the rock fragments seen in sandstone are present in interbedded conglomerate, consistent with derivation from a Precambrian terrane of gneiss and plutonic rocks much like that exposed in the present Sangre de Cristo Range. Comparison of mineral and major oxide abundances reveals a strong association of detrital quartz with SiO2, all other detrital minerals (totaled) with Al2O3, potassium feldspar plus mica with K2O, and plagioclase with Na2O. Thus, major oxide content is a good predictor of detrital mineralogy, although contributions from matrix and cement make these relationships less than perfect. Detrital minerals and major oxides tend to form inverse relationships that reflect mixtures of varying quantities of minerals; when one mineral is abundant, the abundance of others declines by dilution. In arkose of the Minturn and Sangre de Cristo Formations, the

  15. Sedimentology and distribution of Upper Permian lowstand fans, Bredehorn Member, Schuchert Dal Formation, East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Kreiner-Moeller, M.; Piasecki, S.; Stemmerik, L.

    1999-07-01

    The Upper Permian basin of central East Greenland was characterized by shallow marine platform carbonates along the basin margins and over fault crests, and deeper water siliciclastics in the basin centres during the later stages of deposition. The basinal, siliciclastic-dominated succession includes the organic rich, source prone shales of the Ravnefjeld Formation and sandy and silty sediments of the Schuchert Dal Formation. The traditional view of these formations is that they represent discrete stages of basin evolution. However, renewed fieldwork indicates that the lower part of the sandy Bredehorn Member of the Schuchert Dal Formation is time equivalent to the upper part of the Ravnefjeld Formation. The presentation discusses the details.

  16. Important role of magma mixing in generating the Mesozoic monzodioritic-granodioritic intrusions related to Cu mineralization, Tongling, East China: evidence from petrological and in situ Sr-Hf isotopic data

    Science.gov (United States)

    Chen, Bin; Chen, ChangJian

    2016-04-01

    The Mesozoic ore-bearing high-Mg monzodioritic-granodioritic rocks in the Tongling mining district (East China) have been described as having adakitic affinities, and their origin has been attributed to partial melting of delaminated eclogite at depth in the mantle, followed by interaction of the resultant granitic magma with mantle peridotite. Here we present petrological data and in situ Sr isotopic data for zoned plagioclase that are inconsistent with the eclogite-derived model, and instead propose a model that involves magma mixing of siliceous crustal melts and basaltic magma that was derived from metasomatized mantle by subduction zone fluids in an extensional regime. The principal geochemical signatures of these Mesozoic rocks include a hydrous and high-K calc-alkaline affinity, high values of Mg#, high Sr abundances, high Sr/Y and La/Yb ratios, ɛNd(t)=-13.1 to -9.0, and ISr=0.70707-0.70824. The magma mixing model is supported by (1) the common existence of mafic microgranular enclaves (MMEs) and the disequilibrium textures of plagioclase and hornblende, (2) the increase in Ti and Al(IV) from hornblende cores to rims, and the overgrowths of high-Ca pyroxene around hornblende grains as well, indicative of episode of heating and rejuvenation of the magma chamber as a result of recharge of mafic magma, (3) the 87Sr/86Sr ratios of embayed high-Ca cores of plagioclase that are distinctly lower than in the euhedral low-Ca overgrowth rims, (4) negative correlations between whole-rock Nd and Sr isotopic ratios, and (5) the significant differences in the values of ɛHf(t) (-9.5 to -26) within different zircons from the same intrusion. We propose that underplating of hydrous basaltic magma from the metasomatized lithospheric mantle in the lower crust resulted in partial melting of the lower crustal rocks (Precambrian TTG gneisses and amphibolite/granulite) under water-saturated conditions, during which plagioclase decomposed, leaving hornblende-rich restites and

  17. Country-specific strategy and new venture formation in Central and East Europe

    NARCIS (Netherlands)

    Gil, A.; Brouthers, K.D.; Nakos, G.; Brouthers, L.E.

    2006-01-01

    In this study, we examine the influence of three country-specific strategies (market-seeking, client-following and resource-seeking) on new venture formation decisions for firms entering Central and East Europe. We found that market-seeking and resource-seeking strategies tend to influence venture c

  18. Late Permian carbonate concretions in the marine siliciclastic sediments of the Ravnefjeld Formation, East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, J.K. [Univ. of Copenhagen, Geological Inst., Copenhagen (Denmark); Hanken, N.M. [Univ. of Tromsoe, Dept. of Geology, Tromsoe (Norway)

    2002-07-01

    The investigation of carbonate concretions from the Late Permian Ravnefjeld Formation in East Greenland forms part of the multi-disciplinary research project Research of the Sedimentary Basins of North and East Greenland (TUPOLAR). The TUPOLAR project focuses on investigations and evaluation of potential hydrocarbon and mineral resources of the Upper Permian - Mesozoic sedimentary basins. In this context, the Upper Permian Ravnefjeld Formation occupies a pivotal position because it contains local mineralization and has source rock potential for hydrocarbons adjacent to potential carbonate reservoir rocks of the partly time-equivalent Wegener Halvoe Formation. A better understanding of the sedimentary facies and diagenesis of the Ravnefjeld Formation is therefore crucial for an evaluation of the economic evaluation of East Greenland. The original fieldwork was carried out in 1998, when sampling was undertaken of representative carbonate concretions and surrounding beds from a limited number of well-exposed sections in the Ravnefjeld Formation. The sampled material was subsequently investigated by a combination of petrography and stable isotope chemistry to decipher the relationships between the diagenetic development of the carbonate concretions and the mineralization in the sequence. The sequential precipitation of the cement generations was analysed in cement-filled primary voids in gastropods because these showed the most complete development of the different cement generations. The geochemistry of stable isotopes was also studied. During the petrographic work, we became aware of a hitherto unrecognised biota dominated by calcispheres. The well-developed cement generations in primary cavities in skeletal material were used to elucidate the diagenesis. (BA)

  19. Provenance for the Chang 6 and Chang 8 Member of the Yanchang Formation in the Xifeng area and in the periphery Ordos Basin: Evidence from petrologic geochemistry

    Institute of Scientific and Technical Information of China (English)

    LUO; JingLan; LI; Jian; YANG; BingHu

    2007-01-01

    Study indicates that the major paleocurrent and source direction for the Chang 8 Member of the Yangchang Formation, Upper Triassic in the Xifeng area of the southwestern Ordos Basin derived from the southwest direction with the southeast source as the subordinate one. While the Chang 6 Member was influenced not only by the same source as that of the Chang 8 Member from the southwest and the southeast direction, but also affected by the northeast and the east provenance around the Ordos Basin, based upon measurement of paleocurrents on outcrops located in the periphery Ordos Basin, analysis of framework grains and heavy minerals in sandstones of the Chang 6 and Chang 8 Members and their spatial distribution in the study area, combined with characteristics of trace elements and rare-earth elements of mudstones and of a small amount of sandstones in the Xifeng area and outcrops in margin of the Ordos Basin. The Yuole-Xuanma-Gucheng-Heshui-Ningxia region located in the northeastern and the eastern Xifeng area was the mixed source area where the southwest, southeast, northeast and the east sources were convergent till the Chang 6 Member was deposited. The rare earth elements of the Chang 6 and Chang 8 Members are characterized by slight light rare earth-elements (LREE) enrichment and are slightly depleted in heavy rare earth-elements (HREE) with weak to moderate negative abnormal Eu, resulting in a right inclined REE pattern, which implies that the source rocks are closely related with better differential crust material. Analysis on geochemical characteristics of the mudstones and sandstones, features of parent rocks in provenance terranes and tectonic settings shows that source rocks for the Chang 8 Member mainly came from metamorphic and sedimentary rocks in transitional continental and basement uplift terranes with a small amount of rocks including metamorphic, sedimentary and igneous rocks coming from mixed recycle orogenic belt located in the southwest margin of

  20. Impact of long-range desert dust transport on hydrometeor formation over coastal East Asia

    Science.gov (United States)

    Zhang, Zhenxi; Zhou, Wen; Wenig, Mark; Yang, Liangui

    2017-01-01

    Model simulations and hydrological reanalysis data for 2007 are applied to investigate the impact of long-range desert dust transport on hydrometeor formation over coastal East Asia. Results are analyzed from Hong Kong and Shanghai, which are two representative coastal cities of East Asia. Long-range desert dust transport impacts mainly spring and summer clouds and precipitation over coastal East Asia. In spring, clouds and precipitation come mainly from large-scale condensation and are impacted mainly by dust from the Gobi, Sahara, and Thar deserts. These desert dusts can participate in the precipitation within and below the clouds. At lower latitudes, the dust particles act mainly as water nuclei. At higher latitudes, they act as both water nuclei and ice nuclei. The effect of Gobi, Sahara, and Thar dust on large-scale clouds and precipitation becomes stronger at higher latitudes. In summer, clouds and precipitation over coastal East Asia come mainly from convection and are impacted mainly by dust from the Taklamakan, Arabian, and Karakum-Kavir deserts. Most Taklamakan dust particles can participate in precipitation within convective clouds as ice nuclei, while Arabian and Karakum-Kavir dust particles participate only as water nuclei in precipitation below the clouds. The effect of Taklamakan dust on convective clouds and precipitation becomes stronger at lower latitudes. Of all the desert dusts, that from the Gobi and Taklamakan deserts has the relatively largest impact. Gobi dust impacts climate change in coastal East Asia by affecting spring water clouds at higher latitudes.

  1. Geology of East Egypt greenstone field in Neoproterozoic isoand arc: Reconstruction of Iron formation sedimentary environment.

    Science.gov (United States)

    Kiyokawa, S.; Suzuki, T.

    2015-12-01

    Geology of East Egypt greenstone-granit belt which is northern part of Nubia shield was identified neoproterozoic island arc amalgamated sections. There are several iron formation within these greenstone belt. Age data shows this iron formation may be overlaped during 700 Ma Snowball period, how ever, there is no detail report of well preserved ice related evidences. We now started detail field work for identified tectonic reconstruction, original stratigraphy around Iron formation and sedimentary environment during the iron formation sedimentation area. East Egyptian shield was divided three geology, Proterozoic greenstone complex, 700-600 Granitic domes and cover sequence (Hammamet Group). We focus three area to identified sedimentary environment of iron sedimentation. Along the north-south trend of Wadi EL Dabban area are, we named Wadi branch as West site is RW-0 ~ 12, East site is RE-0 ~ 12 from north to south. Northern area is structurally moderate, southern portion is north dipping. Southern portion was intruded by granite and several place contain granitic dikes. Northeast to eastern area are identified younger sedimentary sequence (Hammamat Group) which is unconformablly overlay on the other iron formation bearing greenstone belt. Structurally these area is divided four units. Wadi was divided by right-lateral strike-ship fault. The displacement are more than 3 km. Also north dipping faults are identified.East-West trend fault are divided two units. It is divided NE, SE, NW and NS units.SW unit is most well preserved thick sequence of the Iron formation. SW unit is well preserved iron formation sequence within thick volcaniclastics. This unit mostly north dipping around 40-60 degree. Structural repetition in not well understand. Reconstract stratigraphy in this unit is at least 4000m in thickness. 5 member is identified in this sequence. Several thin iron formations are observed with in pillow lava and volcaniclastic sequence. These very thick

  2. Formation of source and reservoir rocks in a sequence stratigraphic framework Jameson Land East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Piasecki, S.; Dam, G.; Hansen, C.F.; Koppelhus, E.B.; Stemmerik, L.; Surlyk, F.

    1996-12-31

    Sedimentological, biostratigraphical and sequence stratigraphical analyses of East Greenland sedimentary successions with significant source and reservoir qualities have resulted in a major increase in the understanding of their depositional conditions, distribution and geometry`s. A biostratigraphical scheme of the Jurassic succession based on spores, pollen and dinoflaggelate cyst has been constructed for correlation and dating of the very detailed sequence stratigraphical units across the North Atlantic Ocean. Middle and Upper Jurassic dinoflaggelate stratigraphy is closely correlated to Boreal ammonite stratigraphy and deviations from the NW-European standard dinocyst stratigraphy have been recorded. The Upper Permian Folvik Creek Group was deposited in a marine, carbonate-dominated depositional system under arid climatic conditions. The organic-rich shales of the Ravnefjeld Formation represents highstand systems tracts. Reservoir rocks were formed by secondary dissolution of carbonates which were exposed during low relativ sea-level and as sandy turbidites deposited in lowstand systems tract. The uppermost Triassic - lowermost Jurassic Kap Stewart Group was deposited in a large rift lake. Organic-rich shales were deposited distally during lake level highstand. Deltaic reservoir sandstones were deposited in lowstand systems tracts as a respond to forced regressin induced by rapid variations in relative lake-level. The overlying marine Jurassic deposits include several sandstone units with reservoir potential representing both lowstand and high stand systems tracts. The organic rich mudstones were only developed as potential source rocks for oil when the deposition was combined with high marine organic production and basinal anoxic conditions e.g. during deposition of the Middle Jurassic Sortehat Formation and the Upper Jurassic Hareelv Formations. Several of the largestloilfields in the North Sea and on the Norwegian shelf have close analogues in the Jurassic

  3. Formation of source and reservoir rocks in a sequence stratigraphic framework Jameson Land East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Piasecki, S.; Dam, G.; Hansen, C.F.; Koppelhus, E.B.; Stemmerik, L.; Surlyk, F.

    1996-12-31

    Sedimentological, biostratigraphical and sequence stratigraphical analyses of East Greenland sedimentary successions with significant source and reservoir qualities have resulted in a major increase in the understanding of their depositional conditions, distribution and geometry`s. A biostratigraphical scheme of the Jurassic succession based on spores, pollen and dinoflaggelate cyst has been constructed for correlation and dating of the very detailed sequence stratigraphical units across the North Atlantic Ocean. Middle and Upper Jurassic dinoflaggelate stratigraphy is closely correlated to Boreal ammonite stratigraphy and deviations from the NW-European standard dinocyst stratigraphy have been recorded. The Upper Permian Folvik Creek Group was deposited in a marine, carbonate-dominated depositional system under arid climatic conditions. The organic-rich shales of the Ravnefjeld Formation represents highstand systems tracts. Reservoir rocks were formed by secondary dissolution of carbonates which were exposed during low relativ sea-level and as sandy turbidites deposited in lowstand systems tract. The uppermost Triassic - lowermost Jurassic Kap Stewart Group was deposited in a large rift lake. Organic-rich shales were deposited distally during lake level highstand. Deltaic reservoir sandstones were deposited in lowstand systems tracts as a respond to forced regressin induced by rapid variations in relative lake-level. The overlying marine Jurassic deposits include several sandstone units with reservoir potential representing both lowstand and high stand systems tracts. The organic rich mudstones were only developed as potential source rocks for oil when the deposition was combined with high marine organic production and basinal anoxic conditions e.g. during deposition of the Middle Jurassic Sortehat Formation and the Upper Jurassic Hareelv Formations. Several of the largest oilfields in the North Sea and on the Norwegian shelf have close analogues in the Jurassic

  4. Environmental Sensitivity Index (ESI) Atlas: East Florida, maps in portable document format, Volume 1, Volume 2 (NODC Accession 0004150)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set comprises the Environmental Sensitivity Index (ESI) maps in Portable Document Format (.PDF) for the shoreline of East Florida (to encompass the coastal...

  5. Petrological characteristics and provenance analysis of sandstones of Gonjo Formation in Nangqen basin%囊谦盆地贡觉组砂岩岩石学特征与物源分析

    Institute of Scientific and Technical Information of China (English)

    杜后发; 朱志军; 姜勇彪; 杨天南; 刘燕学; 郭福生

    2011-01-01

    在详细观察描述砂岩宏观特征的基础上,对贡觉组碎屑岩骨架组分、常量元素变化规律进行分析,研究了该地区砂岩的岩石学和物源特征,并指出囊谦盆地的沉积序列由下而上(Eg1~Eg5)具砂岩成分成熟度由差变好再变差的趋势.物源演变趋势分析揭示,沉积早期盆地北、西北部的构造运动强烈,为第二段(Eg2)沉积时期提供成熟度很低的碎屑物质,而第一段(Eg1)至第二段(Eg2)沉积时期长石含量降低而岩屑含量递增,构造强度逐渐增强,冲积扇-河流相处于发育阶段;第三段(Eg3)层序发育时,构造运动逐渐减弱,长石含量增高而岩屑含量逐渐降低,但盆地西北、北部继续遭受强烈剥蚀,东部和南部则下降接受沉积,并伴有岩浆活动,湖泊层序发育达到顶峰;第四段(Eg4)和第五段(Eg2)层序沉积时转而接受过渡型再旋回造山带区,长石含量先增加后降低而岩屑含量先降低后增加.%Nangqen basin is a typical representative of the medium-mini-type Paleogene basins controlled by local NNW-treading faults distributed along Jinsha River-Red River belt on the northeastern margin of Qinghai-Tibet plateau.Gonjo Formation is perfectly developed and dominated by a set of thick-bedded, purplish red, red terrigenous clastic rock formation containing gypsum rock in association with large-scale high potassium rocks in Nangqen basin.Combined with results of field geological investigation and analysis and determination of samples as well as quantitative studies of the sandstone framework detrital composition of the Paleogene strata, the authors systematically analyzed petrologic characteristics of the sandstones of the Gonjo Formation in Nangqen basin in the framework of the basin evolution.According to the analysis of geochemical features of sandstones of the Gonjo Formation, the characteristics of paleoclimate, paleoenvironment and provenance in the study area were revealed.For sandstones

  6. Carbon petrology in cometary dust

    Science.gov (United States)

    Rietmeijer, Frans J. M.

    1992-01-01

    Chondritic porous (CP) interplanetary dust particles (IDP's) are collected in the Earth's stratosphere. There exists an extensive database on major and minor element chemistry, stable isotopes, noble gas abundances and mineralogy of many CP IDP's, as well as infrared and Raman spectroscopic properties. For details on the mineralogy, chemistry and physical properties of IDP's, I refer to the reviews by Mackinnon and Rietmeijer (1987), Bradley et al. (1988) and Sandford (1987). Texture, mineralogy (Mackinnon and Rietmeijer, 1987) and chemistry (Schramm et al., 1989; Flynn and Sutton, 1991) support the notion that CP IDP's are a unique group of ultrafine-grained extraterrestiral materials that are distinct from any known meteorite class. Their fluffy, or porous, morphology suggests that CP IDP's probably endured minimal alteration by protoplanetary processes since their formation. It is generally accepted that CP IDP's are solid debris from short-period comets. The evidence is mostly circumstantial but this notion gained significant support based on the comet Halley dust data (Brownlee, 1990). In this paper, I will accept that CP IDP's are indeed cometary dust. The C/Si ratio in CP IDP's is 3.3 times higher than in CI carbonaceous chondrites (Schramm et al. 1989). The intraparticle carbon distribution is heteorogeneous (Rietmeijer and McKay, 1986). Carbon occurs both in oxidized and reduced forms. Analytical electron microscope (AEM) and Raman spectroscopic analyses have shown the presence of several carbon forms in CP IDP's but the data are scattered in the literature. Carbons in cometary CP IDP's are among the most pristine Solar System carbons available for laboratory study. Similar to a recently developed petrological model for the diversity of layer silicates in CP IDP's (Zolensky, 1991) that is useful to constrain in situ aqueous alteration in comets (Rietmeijer and Mackinnon, 1987a), I here present the first effort to develop a petrological concept of carbons

  7. Palaeomagnetism, petrology and geochronology of tertiary magmatic and sedimentary units from Iran

    Science.gov (United States)

    Bina, Mohamad Mansour; Bucur, Ileana; Prevot, Michel; Meyerfeld, Yves; Daly, Lucien; Cantagrel, Jean Marie; Mergoil, Jean

    1986-01-01

    An amount of 160 samples from igneous and sedimentary formations of Palaeocene or Eocene age was collected in Iran, northeast of the Zagros belt. Palaeomagnetic analyses, petrological studies, and K-Ar dating indicate Palaeocene and Eocene palaeomagnetic directions in the Zabol-Baluch region (East Iranian Range) and show that the area remained approximately stable with respect to the Eurasian and African plates from the beginning of the Cainozoic Era. Conversely, large post-Eocene deformations occurred in Central Iran. These large rotations are both clockwise and anti-clockwise. They might have resulted from lateral shears between Arabia and northeast Iran. The Central Elburz underwent a large clockwise rotation which is probably late Oligocene in age. As a whole, our results show that the so-called "Persian Plate" did not exist during the Cainozoic Era.

  8. The Omo Mursi Formation: a window into the East African Pliocene.

    Science.gov (United States)

    Drapeau, Michelle S M; Bobe, René; Wynn, Jonathan G; Campisano, Christopher J; Dumouchel, Laurence; Geraads, Denis

    2014-10-01

    Dating to more than four million years ago (Ma), the Mursi Formation is among the oldest of the Plio-Pleistocene Omo Group deposits in the lower Omo Valley of southwestern Ethiopia. The sedimentary sequence is exposed along a strip ∼35 km by 4 km, but it has received relatively little attention due to the difficult access to this area. Although expeditions to the lower Omo Valley between 1968 and 1973 focused primarily on the Usno and Shungura Formations, survey of the Mursi Formation produced a faunal collection of about 250 specimens deriving exclusively from the Yellow Sands area at the southern extent of the exposures. In 2009, we reinitiated an investigation of the formation by focusing on the most northern exposures, and a new fossil site, Cholo, was identified. Cholo is depositionally similar to the lowermost exposures at the Yellow Sands, although no stratigraphic correlation between the two localities has yet been made. The fossiliferous sediments at Cholo are capped by a prominent vitric tuff that is compositionally distinct from any other known tephra preserved in East African rift basins, including the only known vitric tuff at the Yellow Sands. The faunal assemblage of the Yellow Sands area presents interesting characteristics: the fossils generally show little weathering and include a large proportion of suids (44% of the mammalian fauna) and a small proportion of bovids (14%) compared with other Pliocene African sites. The sample is also unusual in the high frequency of deinotheres (7%). Taxon-specific stable carbon isotopic composition of the Mursi mammals tends to show generally higher proportions of C3 diets compared with other Pliocene sites in East Africa and Chad. This and the particular faunal proportions suggest that the environments represented by the Mursi Formation were more closed than those of other Pliocene sites. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Thermal structure of the lithosphere: a petrologic model.

    Science.gov (United States)

    Macgregor, I D; Basu, A R

    1974-09-20

    A preliminary evaluation of the thermal history of the upper mantle as determined by petrologic techniques indicates a general correspondence with theoretically derived models. The petrologic data supply direct information which may be used as an independent calibration of calculated models, serve as a base for evaluating the assumptions of the theoretical approach, and allow more careful selection of the variables describing mantle thermal properties and processes. Like the theoretical counterpart, the petrological approach indicates that the lithosphere is dominated by two thermal regimes: first, there is a continental regime which cools at rates of the order of 10(9) years and represents the longterm cooling of the earth. Secondly, superimposed on the continental evolution is the thermal event associated with the formation of an oceanic basin, and which may be thought of as a 10(8) year convective perturbation on the continental cycle. Of special interest is petrologic evidence for a sudden steepening of the thermal gradients across the lithosphere-asthenosphere boundary not seen in the theoretical models. The unexpected change of slope points to the need for a critical reevaluation of the thermal processes and properties extant in the asthenosphere. The potential of the petrologic contribution has yet to be fully realized. For a start, this article points to an important body of independent evidence critical to our understanding of the earth's thermal history.

  10. Applied coal petrology: the role of petrology in coal utilization

    Energy Technology Data Exchange (ETDEWEB)

    Isabel Suarez-Ruiz; John Crelling [Instituto Nacional del Carbon (INCAR-CSIC), Oviedo (Spain)

    2008-08-15

    This book is an integrated approach towards the applications of coal (organic) petrology and discusses the role of this science in the field of coal and coal-related topics. Contents are: Introduction 2. Basic factors controlling coal quality and technological behaviour of coal 3. Mining and benefication 4. Coal combustion 5. Coal gasification 6. Coal liquefaction 7. Coal carbonisation 8. Coal-derived carbons 9. Coal as a Petroleum source rock and reservoir rock 10. Environmental and health aspects 11. Other applications of coal petrology.

  11. Journal of Mineralogical and Petrological Sciences

    Science.gov (United States)

    Official journal of Japan Association of Mineralogical Sciences (JAMS), focusing on mineralogical and petrological sciences and their related fields. Journal of Mineralogical and Petrological Sciences (JMPS) is the successor journal to both “Journal of Mineralogy, Petrology and Economic Geology” and “Mineralogical Journal”. Journal of Mineralogical and Petrological Sciences (JMPS) is indexed in the ISI database (Thomson Reuters), the Science Citation Index-Expanded, Current Contents/Physical, Chemical & Earth Sciences, and ISI Alerting Services.

  12. Mobility, Formation and Development of the Academic Profession in Science, Technology, Engineering and Mathematics in East and South East Asia

    Science.gov (United States)

    Yonezawa, Akiyoshi; Horta, Hugo; Osawa, Aki

    2016-01-01

    The academic profession contributes to shaping the capacity and identity of higher education systems. In East and Southeast Asia, there is a need for further discussion on the regional identity characteristics of the academic profession to account for its multiple origins and national and international dimensions. Data from two large-scale…

  13. Organic Petrology of Niutitang Formation in Sancha,Western Hunan Province,China%湘西三岔地区牛蹄塘组黑色岩系有机岩石学特征

    Institute of Scientific and Technical Information of China (English)

    李苗春; 丁海; 焦堃; 姚素平

    2012-01-01

    implication was tentatively discussed.The results show that the macerals are grouped into structural and amorphous macerals.Furthermore the structural maceral can be divided into plant algae(lamellar algae,structural algae Ⅰ,structural algae Ⅱ),animal organic matters,sclerotinite,and vitrinite-like maceral.The main components of amorphous maceral are fine grained maceral and bituminite.Therefore,there are multiple attributes of organic sources for this black rock succession.However,planktonic algae and fungi,benthic macro alga,actitarchs,animal plankton and benthic spongia are the main organic sources on the basis of statistic research,thus the main organic matter types are Ⅰ and Ⅱ.In addition,comprehensive organic petrological study allows to draw a conclusion that the multiple organic resources cause the divergence of organic matter types Ⅰ and Ⅱ,and the benthic macro alga and low large aquatic plants(such as benthic leafy body plants in the shallow sea) is the main components for the type Ⅱ organic matter.The organic petrological study on the Niutitang Formation provides important data for petroleum geological implication research.

  14. Petrology and diagenetic history of the upper shale member of the Late Devonian–Early Mississippian Bakken Formation, Williston Basin, North Dakota

    Science.gov (United States)

    Neil S. Fishman,; Sven O. Egenhoff,; Boehlke, Adam; Lowers, Heather

    2015-01-01

    The organic-rich upper shale member of the upper Devonian–lower Mississippian Bakken Formation (Williston Basin, North Dakota, USA) has undergone significant diagenetic alteration, irrespective of catagenesis related to hydrocarbon generation. Alteration includes precipitation of numerous cements, replacement of both detrital and authigenic minerals, multiple episodes of fracturing, and compaction. Quartz authigenesis occurred throughout much of the member, and is represented by multiple generations of microcrystalline quartz. Chalcedonic quartz fills radiolarian microfossils and is present in the matrix. Sulfide minerals include pyrite and sphalerite. Carbonate diagenesis is volumetrically minor and includes thin dolomite overgrowths and calcite cement. At least two generations of fractures are observed. Based on the authigenic minerals and their relative timing of formation, the evolution of pore waters can be postulated. Dolomite and calcite resulted from early postdepositional aerobic oxidation of some of the abundant organic material in the formation. Following aerobic oxidation, conditions became anoxic and sulfide minerals precipitated. Transformation of the originally opaline tests of radiolaria resulted in precipitation of quartz, and quartz authigenesis is most common in more distal parts of the depositional basin where radiolaria were abundant. Because quartz authigenesis is related to the distribution of radiolaria, there is a link between diagenesis and depositional environment. Furthermore, much of the diagenesis in the upper shale member preceded hydrocarbon generation, so early postdepositional processes were responsible for occlusion of significant original porosity in the member. Thus, diagenetic mineral precipitation was at least partly responsible for the limited ability of these mudstones to provide porosity for storage of hydrocarbons.

  15. Petrology and diagenetic history of the upper shale member of the Late Devonian-Early Mississippian Bakken Formation, Williston Basin, North Dakota

    Science.gov (United States)

    Neil S. Fishman,; Sven O. Egenhoff,; Boehlke, Adam; Lowers, Heather A.

    2015-01-01

    The organic-rich upper shale member of the upper Devonian–lower Mississippian Bakken Formation (Williston Basin, North Dakota, USA) has undergone significant diagenetic alteration, irrespective of catagenesis related to hydrocarbon generation. Alteration includes precipitation of numerous cements, replacement of both detrital and authigenic minerals, multiple episodes of fracturing, and compaction. Quartz authigenesis occurred throughout much of the member, and is represented by multiple generations of microcrystalline quartz. Chalcedonic quartz fills radiolarian microfossils and is present in the matrix. Sulfide minerals include pyrite and sphalerite. Carbonate diagenesis is volumetrically minor and includes thin dolomite overgrowths and calcite cement. At least two generations of fractures are observed. Based on the authigenic minerals and their relative timing of formation, the evolution of pore waters can be postulated. Dolomite and calcite resulted from early postdepositional aerobic oxidation of some of the abundant organic material in the formation. Following aerobic oxidation, conditions became anoxic and sulfide minerals precipitated. Transformation of the originally opaline tests of radiolaria resulted in precipitation of quartz, and quartz authigenesis is most common in more distal parts of the depositional basin where radiolaria were abundant. Because quartz authigenesis is related to the distribution of radiolaria, there is a link between diagenesis and depositional environment. Furthermore, much of the diagenesis in the upper shale member preceded hydrocarbon generation, so early postdepositional processes were responsible for occlusion of significant original porosity in the member. Thus, diagenetic mineral precipitation was at least partly responsible for the limited ability of these mudstones to provide porosity for storage of hydrocarbons.

  16. SMALLER FORAMINIFERS FROM THE LOWER PERMIAN EMARAT FORMATION, EAST OF FIRUZKUH (CENTRAL ALBORZ, IRAN

    Directory of Open Access Journals (Sweden)

    HAMED YARAHMADZAHI

    2016-10-01

    Full Text Available The uppermost Carboniferous-Lower Permian Dorud Group of the Gaduk section in Central Alborz (Iran is more than 44 m-thick; it includes thick succession of conglomerates, quartzarenites, calcareous sandstones, oncolitic fusulinid limestones, sandy limestones, sandstones and shales. The Toyeh, Emarat and Shah Zeid formations of this Group were dated from the Gzhelian to the Sakmarian. A review of the uppermost Gzhelian, Asselian and lower Sakmarian smaller foraminifers of the Emarat Formation of the Gaduk section is here presented. Three foraminiferal biozones are defined: the Nodosinelloides shikhanica-Geinitzina primitiva Zone is latest Gzhelian in age; the Nodosinelloides spp.-Geinitzina spp.-Pseudoacutella partoazari Zone is Asselian; the Rectogordius iranicus gadukensis-Endothyra cf. bamberi Zone is early Sakmarian in age. A new subspecies Rectogordius iranicus gadukensis n. subsp. is described, and the genera Pseudovidalina and Grovesella are discussed. The studied assemblages are correlated with those from the Carnic Alps (Austria-Italy, East European Platform of Russia, the Urals (Russia, Darvaz (Uzbekistan, the northern and central Pamirs (Tajikistan, Central Iran, northern Afghanistan and other classical regions of the Tethyan realm.

  17. Mineral deposit formation in Phanerozoic sedimentary basins of north-east Africa: the contribution of weathering

    Science.gov (United States)

    Germann, Klaus; Schwarz, Torsten; Wipki, Mario

    1994-12-01

    The intra- and epicontinental basins in north-east Africa (Egypt, Sudan) bear ample evidence of weathering processes repeatedly having contributed to the formation of mineral deposits throughout the Phanerozoic. The relict primary weathering mantle of Pan-African basement rocks consists of kaolinitic saprolite, laterite (in places bauxitic) and iron oxide crust. On the continent, the reaccumulation of eroded weathering-derived clay minerals (mainly kaolinite) occurred predominantly in fluvio-lacustrine environments, and floodplain and coastal plain deposits. Iron oxides, delivered from ferricretes, accumulated as oolitic ironstones in continental and marine sediments. Elements leached from weathering profiles accumulated in continental basins forming silcrete and alunite or in the marine environment contributing to the formation of attapulgite/saprolite and phosphorites. The Early Paleozoic Tawiga bauxitic laterite of northern Sudan gives a unique testimony of high latitude lateritic weathering under global greenhouse conditions. It formed in close spatial and temporal vicinity to the Late Ordovician glaciation in north Africa. The record of weathering products is essentially complete for the Late Cretaceous/Early Tertiary. From the continental sources in the south to the marine sinks in the north, an almost complete line of lateritic and laterite-derived deposits of bauxitic kaolin, kaolin, iron oxides and phosphates is well documented.

  18. A preliminary report on coprolites from the Late Triassic part of the Kap Stewart Formation, Jameson Land, East Greenland

    DEFF Research Database (Denmark)

    Milàn, Jesper; Clemmensen, Lars B; Adolphsen, Jan Schulz;

    2012-01-01

    The basal part of the Triassic-Jurassic (Rhaetian-Sinemurian) Kap Stewart Formation, exposed at Jameson Land, East Greenland, yields an extensive coprolite collection from black, parallel-laminated mudstone (“paper shale”), representing an open lacustrine system. Preliminary investigations show...

  19. Depositional environment and organic geochemistry of the Upper Permian Ravenfjeld Formation source rock in East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, F.G.; Piasecki, S.; Stemmerik, L. (Geologoical Survey of Greenland, Copenhagen (Denmark)); Telnaes, N. (Norsk Hydro Research Center, Bergen (Norway))

    1993-09-01

    The Upper Permian Ravnefjeld Formation in East Greenland is composed of shales that laterally pass into carbonate buildups and platforms of the Wegener Halvo Formation. The Ravnefjeld Formation is subdivided into five units that can be traced throughout the Upper Permian depositional basin. Two of the units are laminated and organic rich and were deposited under anoxic conditions. They are considered good to excellent source rocks for liquid hydrocarbons with initial average TOC (total organic carbon) values between 4 and 5% and HI (hydrogen index) between 300 and 400. The cumulative source rocks are separated and enclosed by three units of bioturbated siltstone with a TOC of less than 0.5% and an HI of less than 100. These siltstones were deposited under relatively oxic conditions. The organic geochemistry of the source rocks is typical for marine source rocks with some features normally associated with carbonate/evaporite environments [low Pr/Ph (pristane/phytane), low CPI (carbon preference index), distribution of tricyclic and pentacyclic terpanes]. The establishment of anoxic conditions and subsequent source rock deposition was controlled by eustatic sea level changes. The subenvironment (paleogeographic setting, influx of carbonate material, water depth, salinity) has some influence on a number of bulk parameters [TOC-HI relations, TOC-TS (total sulfur) relations] and, in particular, biomarker parameters such as Pr/Ph and terpane ratios. All the basal shales or shales in the vicinity of carbonate buildups of platforms are characterized by low Pr/Ph, high C[sub 23] tricyclic terpanes, and high C[sub 35] and C[sub 33] hopanes. 52 refs., 20 figs., 3 tabs.

  20. Boundary layer new particle formation over East Antarctic sea ice – possible Hg-driven nucleation?

    Directory of Open Access Journals (Sweden)

    R. S. Humphries

    2015-12-01

    Full Text Available Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on the only day to exhibit extended periods of global irradiance in excess of 600 W m−2. Within the single air mass influencing the measurements, number concentrations of particles larger than 3 nm (CN3 reached almost 7700 cm−3 within a few hours of clouds clearing, and grew at rates of 5.6 nm h−1. Formation rates of 3 nm particles were in the range of those measured at other Antarctic locations at 0.2–1.1 ± 0.1 cm−3 s−1. Our investigations into the nucleation chemistry found that there were insufficient precursor concentrations for known halogen or organic chemistry to explain the nucleation event. Modelling studies utilising known sulfuric acid nucleation schemes could not simultaneously reproduce both particle formation or growth rates. Surprising correlations with total gaseous mercury (TGM were found that, together with other data, suggest a mercury-driven photochemical nucleation mechanism may be responsible for aerosol nucleation. Given the very low vapour pressures of the mercury species involved, this nucleation chemistry is likely only possible where pre-existing aerosol concentrations are low and both TGM concentrations and solar radiation levels are relatively high (∼ 1.5 ng m−3 and ≥ 600 W m−2, respectively, such as those observed in the Antarctic sea ice boundary layer in this study or in the global free troposphere, particularly in the Northern Hemisphere.

  1. Petrology and geochemistry of the orbicular granitoid of Caldera, northern Chile. Models and hypotheses on the formation of radial orbicular textures

    Science.gov (United States)

    Díaz-Alvarado, Juan; Rodríguez, Natalia; Rodríguez, Carmen; Fernández, Carlos; Constanzo, Ítalo

    2017-07-01

    The orbicular granitoid of Caldera, located at the northern part of the Chilean Coastal Range, is a spectacular example of radial textures in orbicular structures. The orbicular body crops out as a 375 m2 tabular to lensoidal intrusive sheet emplaced in the Lower Jurassic Relincho pluton. The orbicular structures are 3-7 cm in diameter ellipsoids hosted in a porphyritic matrix. The orbicules are comprised by a Qtz-dioritic core (3-5 cm in diameter) composed by Pl + Hbl + Qtz + Bt ± Kfs with equiaxial textures and a gabbroic shell (2-3 cm in diameter) characterized by feathery and radiate textures with a plagioclase + hornblende paragenesis. The radial shell crystals are rooted and orthogonally disposed in the irregular contact with the core. The radial shell, called here inner shell, is in contact with the granodioritic equiaxial interorbicular matrix through a 2-3 mm wide poikilitic band around the orbicule (outer shell). The outer shell and the matrix surrounding the orbicules are characterized by the presence of large hornblende and biotite oikocrystals that include fine-grained rounded plagioclase and magnetite. The oikocrystals of both the outer shell and the matrix have a circumferential arrangement around the orbicule, i.e. orthogonal to the radial inner shell. The coarse-grained granodioritic interorbicular matrix present pegmatitic domains with large acicular hornblende and K-feldspar megacrysts. This work presents a review of the textural characteristics of the orbicules and a complete new mineral and whole-rock geochemical study of the different parts of the orbicular granitoid, together with thermobarometric and crystallographic data, and theoretical modeling of the crystallization and element partitioning processes. We propose a model for the formation of the orbicular radial textures consisting of several processes that are suggested to occur fast and consecutively: superheating, volatile exsolution, undercooling, geochemical fractionation and

  2. Organic geochemistry and petrology of barren and Mo-Ni-PGE mineralized marine black shales of the Lower Cambrian Niutitang Formation (South China)

    Energy Technology Data Exchange (ETDEWEB)

    Kribek, Bohdan; Pasava, Jan [Czech Geological Survey, Klarov 3, Praha 1 (Czech Republic); Sykorova, Ivana [Institute of Rock Structure and Mechanics, Czech Academy of Sciences, V Holesovickach 41, 182 09 Praha 8 (Czech Republic); Machovic, Vladimir [Institute of Rock Structure and Mechanics, Czech Academy of Sciences, V Holesovickach 41, 182 09 Praha 8 (Czech Republic); Institute of Chemical Technology, Technicka 5, 166 28 Praha 6 (Czech Republic)

    2007-11-22

    Marine black shales of the Lower Cambrian Niutitang Formation in southern China host Mo-Ni-platinum group elements (PGE) mineralization confined to a phosphate- and pyrite-rich stratiform body (max. 20-cm thick). The H/C atomic ratio, carbon isotopic composition, FTIR spectra of bulk organic matter, and spectra of extractable part of organic matter indicate similar sources and thermal evolution of organic matter in barren and mineralized black shales. The morphology and relative abundance of organic particles in barren and mineralized shales are different. In barren black shales, organic particles comprise only elongated bodies and laminae 2-10 {mu}m across or elongated larger bodies (> 10 {mu}m) with R{sub max} = 2.96-5.21% (Type I particles). Mineralized black shales contain Type I particles in rock matrix (90-95 vol%), small veinlets or irregular organic accumulations (Type II particles, 1-5 vol%) that display weak to well developed mosaic texture and a variable reflectance (R{sub max} 3.55-8.65%), and small (< 1 to 5 {mu}m) rounded or irregular Type III organic particles (1-4 vol%) distributed within phosphate nodules and sulphide rip-up clasts. Type III particles show similar reflectance as particles of Type I in rock matrix. Type I particles are interpreted as remnants of in situ bacterially reworked organic matter of cyanobacteria/algal type, Type II as solidified products or oil-derived material (migrabitumen), and Type III particles as remnants of original organic matter in phosphatized or sulphidized algal/microbial oncolite-like bodies. Equivalent vitrinite reflectances of Type I and III particles in barren and mineralized rocks are similar and correspond to semi-anthracite and anthracite. Micro-Raman spectra of organic particles in rocks display a wide belt in the area of 1600 cm{sup -} {sup 1} (G belt) and approximately the same belt in the area of 1350 cm{sup -} {sup 1} (D belt). The ratio of integrated areas of the two belts correlate with R{sub max

  3. Massive Star Formation of the SGR a East H (sub II) Regions Near the Galactic Center

    Science.gov (United States)

    Yusef-Zadeh, F.; Lacy, J. H.; Wardle, M.; Whitney, B.; Bushouse, H.; Roberts, D. A.; Arendt, R. G.

    2010-01-01

    A group of four compact H II regions associated with the well-known 50 km/s molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of approximately 6 pc. We present a study of ionized gas based on the [Ne II] (12.8 micron) line, as well as multi-frequency radio continuum, Hubble Space Telescope Pa alpha, and Spitzer Infrared Array Camera observations of the most compact member of the H II group, Sgr A East H II D. The radio continuum image at 6 cm shows that this source breaks up into two equally bright ionized features, D1 and D2. The spectral energy distribution of the D source is consistent with it being due to a 25 =/- 3 solar mass star with a luminosity of 8 +/- 3 x 10(exp 4) Solar luminosity . The inferred mass, effective temperature of the UV source, and the ionization rate are compatible with a young O9-B0 star. The ionized features D1 and D2 are considered to be ionized by UV radiation collimated by an accretion disk. We consider that the central massive star photoevaporates its circumstellar disk on a timescale of 3x (exp 4) years giving a mass flux approximately 3 x 10(exp -5) Solar Mass / year and producing the ionized material in D1 and D2 expanding in an inhomogeneous medium. The ionized gas kinematics, as traced by the [Ne II] emission, is difficult to interpret, but it could be explained by the interaction of a bipolar jet with surrounding gas along with what appears to be a conical wall of lower velocity gas. The other H II regions, Sgr A East A-C, have morphologies and kinematics that more closely resemble cometary flows seen in other compact H II regions, where gas moves along a paraboloidal surface formed by the interaction of a stellar wind with a molecular cloud.

  4. The Formative Years of the Modern Corporation: The Dutch East India Company VOC, 1602-1623

    NARCIS (Netherlands)

    O. Gelderblom (Oscar); A. de Jong (Abe); J. Jonker (Joost)

    2012-01-01

    textabstractWith their legal personhood, permanent capital with transferable shares, separation of ownership and management, and limited liability for both shareholders and managers, the Dutch East India Company (VOC) and subsequently the English East India Company (EIC) are generally considered a m

  5. The impact of deindustrialization and unemployment on family formation and fertility in East Germany.

    Science.gov (United States)

    Fleischhacker, J

    1995-01-01

    With the fall of the Berlin Wall on November 9, 1989, East Germany entered a process of transition from a centrally planned economy to a market economy. Since then, the number of marriages and births in former East Germany have declined by 65% and 1.3 million people have migrated west. 0.36 million have migrated from West to East Germany. Indeed, the demographic situation in East Germany has fundamentally changed in many ways since 1989. The author analyzes these changes, noting that trends toward deindustrialization and a high level of unemployment especially among women are now basic features of demography in the East. The dismantling of industrial capacities accompanying the economic transformation process in East Germany was not only the result of differences in productivity between East and West Germany, but also of regional strains upon the environment. The author also points out that the economic policy of the former government of East Germany and the resulting environmental damage to the region have not lead to major changes in birth and mortality rates.

  6. Palynostratigraphy of the Sanganeh Formation at the East and Central Kopeh-Dagh Basin based on dinoflagellate cysts

    Directory of Open Access Journals (Sweden)

    Narges Shokri

    2015-05-01

    Full Text Available The Sanganeh Formation (Lower Cretaceous has cropped out across the Kopeh-Dagh Basin. The formation conformably overly the Aptian Sarcheshmeh Formation and is in turn overlain conformably by glauconitic sandstone of the Aitamir Formation. The considered formation in eastern and central parts of the basin comprises predominantly dark shale with some interbeds of limestone and siltstone. In order to analyse dinoflagellate content of this rock unit , four stratigraphic sections from east to the center of the basin including Karizak (320m, Mozduran (355m, Sanganeh (550m, and Qarah-Su (580m were measured and sampled palynologically. A total of 370 rock samples taken from the four sections were processed palynologically and scanned under a light microscope. Of these, two sections including Karizak and Mozduran were barren of any preserved dinocysts while, the samples from other two sections (Sanganeh and Qarah-Su yielded a relatively diverse and well preserved assemblage. According to the recognized dinocysts, two zones DZ1 and DZ2 were established in Sanganeh and Qarah-Su sections. The differentiated dinozones were coincident to Odontochitina operculata and Pseudoceratium turneri which are index for late Aptian-early Albian for the Sanganeh Formation at the mentioned stratigraphic sections. In addition, distribution and dispersion of dinoflagellate cyst contents indicate an increasing trend of the depth from east to the central parts of the Kopeh-Dagh Basin.

  7. Distribution,formation and evolution of sand ridges on the East China Sea shelf

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the integrated results of multiple data types including MBES (Multi-Beam Echo Sounding) and historical topography maps,the LSR (Linear Sand Ridges) on the ECS (East China Sea) shelf are identified,divided into subareas,and classified.The distribution of sand ridge crests is also established.The strikes of the LSR on the ECS shelf fall in a normal distribution with the center point being 155° azimuth with additional peak points at 125°,130°,140°,and 180° azimuth.The distribution of the ECS shelf sand ridges is congested in the central area,sparse in the south and north ends,divergent and bifurcated in the eastern area,and densely convergent in the western area.The LSR are divided into seven subzones according to the strikes and distribution of the sand ridges;estuary mouth ridges and open shelf sand ridges are identified and marked out.The high amplitude change of sea level resulting from the glacial-interglacial cycle is the main cause of the vast development of sand ridges on the ECS shelf.Abundant sediments on the shelf carried by the PYR (Paleo-Yangtze River) are the material source for the LSR formation,and the negative seafloor topography influences the strikes of LSR.Based on the effects of LSR distribution,change of sea level,and the simulation of ancient tidal currents,the evolution of the LSR on the ECS shelf is divided into four main stages:Stage Ⅰ before 14.5 ka BP,Stage Ⅱ between 12 and 14 ka BP,Stage Ⅲ from 1.5 to 9.5 ka BP,and Stage Ⅳ after 9 ka BP.

  8. Palynology and paleoecology of Sarcheshmeh and Sanganeh formations at Baghak section (east of Kopeh-Dagh

    Directory of Open Access Journals (Sweden)

    Mahjooneh Keshmiri

    2014-11-01

    Full Text Available 1-Introduction The Kopeh-Dagh as an inverted basin (Allen et al. 2003 is extended from the east of the Caspian Sea to NE Iran, north Afghanistan and Turkmenistan. Following the closure of palaeo-Tethys in the Middle Triassic and the opening of Neo-Tethys during the early to middle Jurassic, the Kopeh-Dagh basin formed during the early to middle Jurasic. Sedimentation took place continuously from the Jurassic through the Neogene time in the Kopeh-Dagh basin (Afshar-Harb 1979. The first geological study on these strata was done by Amiranian oil company from 1937 to 1938. Many biological and stratigraphical studies had been carried on later on this basin. Kalantari (1969, Seyed-Emami (1980, Seyed-Emami and Aryai (1981, Seyed-Emami et al. (1984, 1994, 1996, Immel et al (1997, Raisossadat and Mousavi-Harami (2000, Raisossadat (2004, 2006 and Mahanipour et al. (2011 are among those who studied the biostratigraphy and sedimentology of the Cretaceous strata of this basin. In this paper we report on palynological and paleoecological data from two mid-Cretaceous formations (Sarcheshmeh and Sanganeh in Baghak section situated in eastern part of Kopeh-Dagh basin. 2-Materials and Methods Fifteen samples from the Sarcheshmeh and thirty five samples from Sanganeh formation were processed palynologically. The preparation method of Traverse, 2007 was used. Cold hydrochloric (20% and hydrofluoric (50% acids were used to dissolve carbonates and silicates. The residue was neutralized and centrifuged in ZnCl2 (specific gravity 1.9, then sieved at 15 um using a nylon mesh, and mounted on microscope slides using liquid Canada balsam. Three slides were made from each sample. The microscope slides were examined under a light microscope and the index dinocysts were photographed and presented in two plates. In order to study palynofacies, in each slide numbers of organic materials including phytoclasts, marine palynomorphs and non-structural organic materials were

  9. The Poster: A Petrologic Exercise For The Resource-Challenged

    Science.gov (United States)

    Flood, T. P.

    2003-12-01

    The scientific poster is a common format for transmitting information and can be used as a petrologic exercise that may be particularly beneficial for those programs with limited resources. For example, the Saint Norbert College geology program was founded in 1987 and a traditional geology major established in 1994. We have high quality petrographic microscopes and excellent on-campus computing resources but otherwise lack common facilities such as a rock preparation room and instrumentation for obtaining research quality geochemical data such as XRF or SEM. The petrology poster exercise is designed to mimic the formative stages of a research project from fieldwork through geochemical analysis. A background literature search on a regional rock assemblage, usually suggested by the instructor, is conducted by the students. A specific petrologic aspect, such as the troctolitic portion of the Duluth Complex, is selected for investigation. Fieldwork consists of detailed outcrop and handsample descriptions, with approximately ten samples collected for thin section analysis. Geochemical data is culled from the literature by the instructor and computer modeled by the students using standard petrologic modeling programs such as IGPET. Having characterized the rock in detail, the students make interpretations of their data and more importantly, formulate research questions for future investigation. The final poster summarizes a student's work and is presented to their peers for critique. The goal of this semester-long exercise is to provide a near-professional research experience to the students for limited costs (i.e. site field trip and professional preparation of the thin sections). Additional benefits include: in-depth instruction related to writing an abstract, enhanced computer graphic skills related to poster construction, and a final product that makes an excellent springboard to a senior thesis.

  10. Formation and Cross-Cumulus Migration of Silica-Rich Liquids in the Skaergaard Intrusion, East Greenland

    Science.gov (United States)

    Larsen, R. B.; Sorensen, B. E.; Muller, A.

    2008-12-01

    In a recent publication on the Skaergaard intrusion evidence for the formation of silica-rich melts by silicate- silicate liquid immiscibility was proposed (Jakobsen et al., Geology 33, 2005). Coexisting iron-rich and silica- rich microscopic melt inclusions were trapped in apatite during crystallisation of the Skaergaard melts. Given this evidence for liquid immiscibility it is possible to explain the formation of macroscopic accumulations of silica rich entities throughout the magmatic stratigraphy. Previously, the formation and emplacement of these granophyric entities were challenging to explain. Examples include decimetre to metre size granophyric /melano-granophyric aggregates in either gabbroic pegmatite, in chimney shaped columns intersecting the layering or in isolated pods. Particularly, the presence of numerous granophyric pods a few metres above large gabbroic pegmatite were enigmatic. Moving the granophyric melts from the pegmatite where they formed (Larsen and Brooks, Journal of Petrology 35, 1994) and several metres across the magmatic stratigraphy would require unconsolidated cumulates i.e. a crystal mush. Geothermobarometric estimates from fluid inclusions, amphibole and feldspars show that the silica-rich aggregations solidified between 900 and 660 C at P from 1.8 to 2.9 kb. However, to be true products of liquid immiscibility they should form at T > 1050 C. With an average of 960 ppm Zr, the silica-rich aggregates are extremely Zr rich. Zr saturation thermometry imply minimum T's of 1070 (c. 2000 ppm Zr) to 900 C (c. 700 ppm Zr). Ti in Zr thermometry is progressing and may further constrain the T of formation. Although large uncertainties apply, a T of 1070 C or higher, would agree with a formation by liquid immiscibility. Assuming T > 1070 C the cumulus stratigraphy was unconsolidated with > 30 vol% intercumulus melts in the lower part of the magmachamber. With a density of 2.4-2.6 g/cm3, the silica-rich melts were much lighter than the ambient

  11. Petrologic implications of plate tectonics.

    Science.gov (United States)

    Yoder, H S

    1971-07-30

    Petrologists can make significant contributions to the plate tectonic concept. Fixing the stability fields of the principal rock types involved will provide the limits of pressure and temperature of the various environments. Experimental determination of the partition coefficients of the trace elements will be helpful. Studies of the partial melting behavior of possible parental materials in the absence and presence of water, especially the undersaturated region, will contribute to the understanding of magma production. Experimental observations on the rheological properties of the peridotites below and just above the solidus will lead to a better evaluation of the convective mechanism. Measurement of the fundamental properties of rocks, such as the density of solids and liquids at high pressures and temperatures, would contribute to understanding the concepts of diapiric rise, magma segregation, and the low-velocity zone. Broader rock sampling of the oceanic areas of all environments will do much to define the petrologic provinces. The field petrologist specializing in the Paleozoic regions and Precambrian shields can contribute by examining those regions for old plate boundaries and devising new criteria for their recognition.

  12. Conodonts, stratigraphy, and relative sea-level changes of the tribes hill formation (lower ordovician, east-central New York)

    Science.gov (United States)

    Landing, E.D.; Westrop, S.R.; Knox, L.A.

    1996-01-01

    Tremadocian onlap is recorded by the Tribes Hill Formation. The formation is a lower Lower Ordovician (upper conodont Fauna B Interval(?)- Rossodus manitouensis Zone) depositional sequence that unconformably overlies the Upper Cambrian Little Falls Formation. Depositional environments and stratigraphy indicate that the Tribes Hill was deposited on a wave-, not tide-, dominated shelf and that a uniform, 'layer-cake' stratigraphy is present. The deepening-shoaling sequence of the Tribes Hill includes the: 1) Sprakers Member (new; peritidal carbonate and overlying tempestite limestone and shale); 2) Van Wie Member (new; subtidal shale and limestone); 3) Wolf Hollow Member (revised; massive carbonates with thrombolitic cap); and 4) Canyon Road Member (new; glauconitic limestone and overlying evaporitic dolostone). The shoaling half-cycle of the Tribes Hill is older than a shoaling event in western Newfoundland, and suggests epeirogenic factors in earliest Ordovician sea-level change in east Laurentia. Conodont and trilobite biofacies track lithofacies, and Rossodus manitouensis Zone conodonts and Bellefontia Biofacies trilobites appear in the distal, middle Tribes Hill Formation. Twenty-four conodont species are illustrated. Ansella? protoserrata new species, lapetognathus sprakersi new species, Leukorhinion ambonodes new genus and species, and Laurentoscandodus new genus are described.

  13. Formation of metamorphic core complexes in non-over-thickened continental crust: A case study of Liaodong Peninsula (East Asia)

    Science.gov (United States)

    Wang, Kun; Burov, Evgueni; Gumiaux, Charles; Chen, Yan; Lu, Gang; Mezri, Leila; Zhao, Liang

    2015-12-01

    Pre-thickened hot orogenic crust is often considered a necessary condition for the formation of continental metamorphic core complexes (MCCs). However, the discovery of MCCs in the Liaodong Peninsula, where the crust has a normal thickness (~ 35 km), challenges the universality of this scenario. Therefore, we implement a series of 2-D numerical thermo-mechanical modeling experiments in which we investigate the conditions of MCC formation in normal crusts, as well as the relationships between the underlying mechanisms and the syn-rift basin evolution. In these experiments, we explore the impact of the lithostratigraphic and thermo-rheological structure of the crust. We also examine the lithosphere thickness, strain softening, extension rate, and surface erosion/ sedimentation processes. The experiments demonstrate that high thermal gradients and crustal heterogeneities result only in a symmetric spreading dome, which is geometrically incompatible with the observations of the MCCs in the Liaodong Peninsula. According to our further findings, the strain softening should play a key role in the development of asymmetric strain localization and domal topography uplift, while synchronous surface erosion controls the polarity of the syn-rift basin. The synthetic model data are compatible with the geological observations and cooling history based on the thermo-chronology for the eastern part of the East Asia during the late Mesozoic to the early Cenozoic. The model-predicted P-T-t paths are essentially different from those inferred for the other known MCCs, confirming the exceptional character of the MCC formation in the wide rift system of the East Asia.

  14. Sedimentary Microfacies and Evolution of the Lower Karamay Formation in mid and east of 7th Block, Karamay Oilfield%克拉玛依油田七中东区克下组沉积微相及演化

    Institute of Scientific and Technical Information of China (English)

    张代燕; 彭军; 王子强

    2012-01-01

    In mid and east of 7th block.Karamay Oilfield,the sedimentary characteristics of the Lower Karamay Formation were not recognized clearly, which impressed exploiting the remaining oil and deploying the plan. Through the analysis of depositional environment, core facies and electrofacies,it is concluded that piedmont pluvial fades were developed during the deposition of the Lower Karamay Formation. On the basis of this area, four subfacies were divided(the inner belt of root fan, the outer belt of root fan, middle fan and fan edge).In bottom section of formation, the glutenite of root fan is dominant in the facies distribution of plane; In middle section, the glutenite of middle fan interbed mudstone is dominant; In top section, the mudstone intersperse with glutenite is predominant. Based on the piedmont pluvial facies, eight microfacies were divided(the gravel of channel flow, the gravel of laminar flow, sheetflood sand, sheetflood fine grain, braided channel, runoff channel, overflow sand and overflow fine grain). And the characteristics of petrology, construction, structure and electric were described. The distribution of facies in plane and certical evolution were indicated, and the sedimentary model of the area was established.%通过对区域地质背景、岩心相、测井相分析,并结合分析化验等资料,认为克拉玛依油田七中、东区克下组沉积相为山麓-洪积相.将本区划分为扇根内带、扇根外带、扇中和扇缘4个亚相.从下到上,克下组沉积相平面分布从以扇根砂砾岩为主,演化为以扇中砂砾岩与泥岩互层为主,最终转变为扇缘泥岩夹少量砂砾岩.划分了槽流砾石体、片流砂砾体、漫洪砂体、漫洪细粒沉积、辫流水道、径流水道、漫流砂体和漫流细粒共8个沉积微相,描述了各微相岩石学特征、结构特征、构造特征和电性特征,指出沉积相平面展布及垂向演化特征,建立了研究区沉积模式.

  15. New particle formation under the influence of the long-range transport of air pollutants in East Asia

    Science.gov (United States)

    Chandra, Indra; Kim, Seyoung; Seto, Takafumi; Otani, Yoshio; Takami, Akinori; Yoshino, Ayako; Irei, Satoshi; Park, Kihong; Takamura, Tamio; Kaneyasu, Naoki; Hatakeyama, Shiro

    2016-09-01

    Field observations to investigate the correlation between New Particle Formation (NPF) and the long-range transport of air pollutants in the East Asia region were carried out on a rural Island of Japan in the East-China Sea (Fukue Island, 32.8°N, 128.7°E) over three periods (February 23 to March 7, 2013; November 7 to 20, 2013; and November 2 to 24, 2014). Frequent NPF events were identified (16 events in 50 days), typically in association with sudden increases in particle number concentrations and the successive growth of particles to mobility diameters of several tens of nanometers. The NPF events were classified into two types (A and B) according to the initially detected particle sizes (onset diameters). Type-A consisted of strong NPF events with onset diameters as small as 5 nm. Type-B consisted of NPF events whose onset (<10 nm) was not clearly identifiable. The correlations of SO2 concentrations, solar radiation, PM2.5 concentrations, and chemical composition were analyzed based on the types of NPF events.

  16. Organic Petrological Studies on Immature Source Rocks

    Institute of Scientific and Technical Information of China (English)

    李贤庆; 熊波; 钟宁宁; 马安来; 王铁冠; 张爱云

    2004-01-01

    Organic petrology is a marginal science that is quite practicable. At present, it has developed into a routine research tool that is widely applied in petroleum exploration and assessment. Based on several years' research of the authors, this paper presents the advances in organic petrological studies on immature source rocks, including the classification and characteristics of macerals, the composition of macerals and types of organic matter, the abundance and evolution of organic matter, oil-prone macerals, hydrocarbon generation and expulsion. All these results show that organic petrology is of considerable value pertaining to its application in the assessment of immature oil and gas. The immature source rocks consist of various macerals with obvious heterogeneity, contain different hydrocarbon-generating macerals with different oil thresholds and oil peaks, and show a two-staged evolutionary pattern of organic matter.

  17. The Tendaguru formation of southeastern Tanzania, East Africa: An alternating Late Jurassic to Early Cretaceous palaeoenvironment of exceptional status

    Science.gov (United States)

    Sames, B.

    2009-04-01

    Dinosaur remains have inspired considerable scientific interest in the Tendaguru formation of southeastern Tanzania during the 20th century; however, this formation is exceptional in many other respects. The Late Jurassic to Early Cretaceous deposits of the Tendaguru formation in the southwestern Tethys are unique because they represent a marginal marine palaeoenvironment with nonmarine faunal and floral content. It is a threefold succession of marginal marine to terrestrial, carbonate-siliciclastic sediments with cyclic character, consisting of three transgressive-regressive cycles. Revisitation of the type locality (the Tendaguru, a hill approximately 60km northwest of the town of Lindi) by a German-Tanzanian expedition in summer 2000 (Heinrich et al., 2001) resulted in a new standard section (hitherto unpublished, the informal terminology is indicated by the use of lower case in Tendaguru formation), a refined environmental model (Aberhan et al., 2002) and many new insights towards its geology (with evidence of event-sedimentation, Bussert and Aberhan, 2004), biostratigraphy and a better understanding of the Tendaguru palaeo-ecosystems and the palaeoclimate. Within the scope of the designation of a new standard section at the type locality, calcareous microfossils (ostracods, charophytes) have been described to supplement the ongoing discussion about the age and palaeoecology of the Tendaguru formation (Sames, 2008). Although only a few unevenly distributed layers across the section produced calcareous microfossils, the results are very promising. A total of 40 ostracode and 2 charophyte taxa could be distinguished. The non-marine part of the ostracod fauna provides an important contribution to the documentation of Purbeck/Wealden-type nonmarine palaeoenvironments and its microfaunas and -floras previously unknown from East Africa. The marine faunal part belongs to a relatively endemic southern (Gondwana) fauna. Together with other fossil groups, the

  18. Refining a Proposal to Build Data-Rich Rock Suites for Learning Petrology

    Science.gov (United States)

    Wirth, K. R.; Davidson, C.; Creasy, J. W.

    2003-12-01

    One of the outcomes from the 2003 Teaching Petrology workshop held in Bozeman, MT was a call for the development of a series of data-rich rocks suites that could be used to help students learn fundamental petrologic processes and concepts such as partial melting, magmatic differentiation, and phase equilibria. These suites would include detailed field, structural, geochemical, and geochronologic data that could be used in short lecture demonstrations, laboratory exercises, multi-week activities or semester-long projects. The motivation behind the development of these suites is the growing understanding in the education community that hands-on, problem-based learning activities that allow students to build their own knowledge are more effective than most traditional lecture formats. In discovery-based environments students learn to pose questions, work with data, manage ambiguity, and synthesize diverse observations. Many existing rocks suites used in petrology courses consist of rocks that were not necessarily selected to facilitate learning of important petrologic processes, or to develop higher order skills in a discovery-based setting. Our proposal is to develop a collection of genetically related rocks that can be used to discover fundamental petrologic concepts through guided data collection, interpretation, and synthesis by students and faculty. The use of suites in this manner helps develop a "community of learners" atmosphere in a course, where the outcome is perhaps not well defined and could change from year to year depending on the interests of the students and faculty involved. In addition, we hope these suites will be developed and used by several institutions, thus modeling the process of modern research by promoting sharing of equipment, data, ideas, and expertise perhaps through the use of a dedicated web site for each suite. This abstract solicits interest in and feedback from the community on the development of a series of data-rich rock suites

  19. Formation mechanism and model for sand lens reservoirs in the Jiyang Sub-basin, East China

    Institute of Scientific and Technical Information of China (English)

    LI; Pilong; PANG; Xiongqi; CHEN; Dongxia; ZHANG; Shanwen

    2004-01-01

    The Bohai Bay basin comprises some very important and well documented subtle traps known in China, which have been the major exploration focus and have become a major petroleum play since the 1990s. However, recent exploration showed that the oil-bearing properties of some sand lens reservoirs may vary significantly and the accumulation mechanisms for these lithological subtle traps are not well understood. Based on statistical analysis of oil-bearing properties for 123 sand lens reservoirs in the Jiyang Sub-basin and combined with detailed anatomy of typical sand lens reservoirs and NMR experiments, it has been shown that the structural and sedimentary factors, hydrocarbon generation and expulsion conditions of the surrounding source rocks, as well as the petrophysical properties of sand lens reservoirs are the main controlling factors for the formation of sand lens reservoirs. The formation of a sand lens reservoir depends on the interaction between the hydrocarbon accumulation driving force and the resistance force. The driving force is made up of the differential capillary pressure between sandstones and sources rocks and the hydrocarbon diffusion force, and as well as the hydrocarbon expansion force. The resistance force is the friction resistance force for hydrocarbons and water to move through the pore throats of the sand lens. The sedimentary environment, source rock condition and sand reservoir properties can change from unfavorable to favorable depending on the combination of these factors. When these three factors all reach certain thresholds, the sand lens reservoirs may begin to be filled by hydrocarbons. When all of these conditions become favorable for the formation of sand lens reservoirs, the reservoir would have high oil saturation. This approach has been applied to evaluating the potential of petroleum accumulation in the sand lens reservoirs in the third member of the Neogene Shahejie Formation in the Jiyang Sub-basin.

  20. The Jurassic of Denmark and Greenland: Shallow marine syn-rift sedimentation: Middle Jurassic Pelion Formation, Jameson Land, East Greenland

    Directory of Open Access Journals (Sweden)

    Engkilde, Michael

    2003-10-01

    Full Text Available The Middle Jurassic Pelion Formation – Fossilbjerget Formation couplet of Jameson Land, East Greenland, is a well-exposed example of the Middle Jurassic inshore–offshore successions characteristicof the rifted seaways in the Northwest European – North Atlantic region. Early Jurassic deposition took place under relatively quiet tectonic conditions following Late Permian – earliest Triassic and Early Triassic rift phases and the Lower Jurassic stratal package shows an overall layer-cake geometry. A long-term extensional phase was initiated in Middle Jurassic (Late Bajocian time, culminated in the Late Jurassic (Kimmeridgian–Volgian, and petered out in the earliest Cretaceous (Valanginian. The Upper Bajocian – Middle Callovian early-rift succession comprises shallow marine sandstones of the Pelion Formation and correlative offshore siltstones of theFossilbjerget Formation. Deposition was initiated by southwards progradation of shallow marine sands of the Pelion Formation in the Late Bajocian followed by major backstepping in Bathonian–Callovian times and drowning of the sandy depositional system in the Middle–Late Callovian. Six facies associations are recognised in the Pelion–Fossilbjerget couplet, representing estuarine, shoreface, offshore transition zone and offshore environments. The north–southtrendingaxis of the Jameson Land Basin had a low inclination, and deposition was sensitive to even small changes in relative sea level which caused the shorelines to advance or retreat over tens to several hundreds of kilometres. Eight composite sequences, termed P1–P8, are recognised and are subdivided into a total of 28 depositional sequences. The duration of the two orders of sequences was about 1–2 Ma and 360,000 years, respectively. The Upper Bajocian P1–2 sequencesinclude the most basinally positioned shallow marine sandstones, deposited during major sealevel lowstands. The lowstands were terminated by significant marine

  1. Holocene Formation of Heald Sand Bank on the East Texas Inner Continental Shelf

    Science.gov (United States)

    Swartz, J. M.; Cleveland, V.; Gulick, S. P. S.; Goff, J. A.

    2015-12-01

    Heald Bank is a Gulf of Mexico sand bank located ~50 km off the coast of east Texas on the inner continental shelf. The bank is proposed to be a remnant of barrier islands drowned and thus preserved during an episode of rapid sea level rise. For this hypothesis to be true, the transgressive ravinement that marks the erosion by the shoreline moving from shelf edge towards the modern location would by definition postdate and thus be stratigraphically above the bank. To test this hypothesis we present ~90 km of Compressed High Intensity Radar Pulse (CHIRP) and Multi-channel seismic (MCS) data collected from the University of Texas Geophysics marine field course during 2008, 2013, and 2014. In these data, there are several visible underlying channels beneath Heald Bank. These channels have channel fill which are truncated by an overlying erosional surface, which we interpret to be the transgressive ravinement from sea level rise. However, this interpretation places the ravinement below the sand bank, meaning it could not have been drowned and buried by a rapid sea level rise event. Thus, Heald Bank and potentially the related inner shelf banks (Thomas, Shepard, and Sabine) from eastern Texas to western Louisiana cannot be used as an example of coastal response to climate change and sea level rise. We examine alternate origins for the banks and their sand using published cores as well as age models and integrating them with our seismic data. One possibility is that the sand was sourced from the nearby Sabine River system immediately following local transgression or the sand was remobilized from sediment fill within underlying paleo-river channels imaged below the Heald Bank. In either case Heald Bank appears not to serve as an indicator for rapid sea-level rise, yet could be an important analog for sand transport mechanisms offshore.

  2. Multi-seeded multi-mode formation of embedded clusters in the RMC: Structured star formation toward the south-east boundary

    CERN Document Server

    Smith, J Z L M D

    2005-01-01

    The Rosette Molecular Complex contains embedded clusters with diverse properties and origins. We have previously explored the shell mode of formation in the north (Regions A & B) and the massive concentrations in the ridge (Region C). Here, we explore star formation towards the south of the complex, Region D, based on data from the spatially complete 2 Micron All Sky Survey. We find that stars are forming prolifically throughout this region in a highly structured mode with both clusters and loose aggregates detected. The most prominent cluster (Region D1) lies in the north-center. This cluster is over 20 pc to the south of the Monoceros ridge, the interface of the emerging young OB cluster NGC 2244 with its ambient molecular clouds. In addition, there are several branches stemming from AFGL 961 in Region C and extending to the south-east boundary of the cloud. We invoke a tree model to interpret this pattern, corresponding to probable tracks of abrupt turbulent excitation and subsequent decay. Alternative...

  3. Petrology and Geochemistry of LEW 88663 and PAT 91501: High Petrologic L Chondrites

    Science.gov (United States)

    Mittlefehldt, D. W.; Lindstrom, M. M.; Field, S. W.

    1993-07-01

    Primitive achondrites (e.g., Acapulco, Lodran) are believed to be highly metamorphosed chondritic materials, perhaps up to the point of anatexis in some types. Low petrologic grade equivalents of these achondrites are unknown, so the petrologic transition from chondritic to achondritic material cannot be documented. However, there are rare L chondrites of petrologic grade 7 that may have experienced igneous processes, and study of these may yield information relevant to the formation of primitive achondrites, and perhaps basaltic achondrites, from chondritic precursors. We have begun the study of the L7 chondrites LEW 88663 and PAT 91501 as part of our broader study of primitive achondrites. Here, we present our preliminary petrologic and geochemical data on these meteorites. Petrology and Mineral Compositions: LEW 88663 is a granular achondrite composed of equant, subhedral to anhedral olivine grains poikilitically enclosed in networks of orthopyroxene and plagioclase. Small grains of clinopyroxene are spatially associated with orthopyroxene. Troilite occurs as large anhedral and small rounded grains. The smaller troilite grains are associated with the orthopyroxene-plagioclase networks. PAT 91501 is a vesicular stone containing centimeter-sized troilite +/- metal nodules. Its texture consists of anhedral to euhedral olivine grains, anhedral orthopyroxene grains (some with euhedral clinopyroxene overgrowths), anhedral to euhedral clinopyroxene, and interstitial plagioclase and SiO2-Al2O3-K2O- rich glass. In some areas, olivine is poikilitically enclosed in orthopyroxene. Fine-grained troilite, metal, and euhedral chromite occur interstitial to the silicates. Average mineral compositions for LEW 88663 are olivine Fo(sub)75.8, orthopyroxene Wo(sub)3.4En(sub)76.2Fs(sub)20.4, clinopyroxene Wo(sub)42.6En(sub)47.8Fs(sub)9.6, plagioclase Ab(sub)75.0An(sub)21.6Or(sub)3.4. Mineral compositions for PAT 91501 are olivine Fo(sub)73.8, orthopyroxene Wo(sub)4.5En(sub)74.8Fs

  4. Formation and metamorphic evolution of the Douling Complex from the East Qinling Mountains

    Institute of Scientific and Technical Information of China (English)

    张寿广; 魏春景; 赵子然; 沈洁

    1996-01-01

    The Douling Complex occurs as a Precambrian tectonic block distributed between the North China and Yangtze plates and has a protracted evolutional history. It is composed of various metamorpnic intrusives and supracrustal rocks. According to the studies on geology and geochronology, it can be concluded that the complex may have been formed in the early Proterozoic, about 2000 Ma ago and experienced two phases of regional metamorphism during the Jinningian and late Caledonian-early Hercynian. It can be correlated with the Qinling Complex from the North Qinling Mountains in lithic assemblage, formation age, tectonic setting and metamorphism, and is probably a thrust nappe split from the Qinling Complex.

  5. Modeling and Databases for Teaching Petrology

    Science.gov (United States)

    Asher, P.; Dutrow, B.

    2003-12-01

    With the widespread availability of high-speed computers with massive storage and ready transport capability of large amounts of data, computational and petrologic modeling and the use of databases provide new tools with which to teach petrology. Modeling can be used to gain insights into a system, predict system behavior, describe a system's processes, compare with a natural system or simply to be illustrative. These aspects result from data driven or empirical, analytical or numerical models or the concurrent examination of multiple lines of evidence. At the same time, use of models can enhance core foundations of the geosciences by improving critical thinking skills and by reinforcing prior knowledge gained. However, the use of modeling to teach petrology is dictated by the level of expectation we have for students and their facility with modeling approaches. For example, do we expect students to push buttons and navigate a program, understand the conceptual model and/or evaluate the results of a model. Whatever the desired level of sophistication, specific elements of design should be incorporated into a modeling exercise for effective teaching. These include, but are not limited to; use of the scientific method, use of prior knowledge, a clear statement of purpose and goals, attainable goals, a connection to the natural/actual system, a demonstration that complex heterogeneous natural systems are amenable to analyses by these techniques and, ideally, connections to other disciplines and the larger earth system. Databases offer another avenue with which to explore petrology. Large datasets are available that allow integration of multiple lines of evidence to attack a petrologic problem or understand a petrologic process. These are collected into a database that offers a tool for exploring, organizing and analyzing the data. For example, datasets may be geochemical, mineralogic, experimental and/or visual in nature, covering global, regional to local scales

  6. STRATIGRAPHY AND PALYNOLOGY OF THE UPPER TRIASSIC NAYBAND FORMATION OF EAST-CENTRAL IRAN

    Directory of Open Access Journals (Sweden)

    SIMONETTA CIRILLI

    2005-07-01

    Full Text Available A palynological study of the Nayband Formation (central eastern Iran has been carried out in order to review and update its stratigraphic framework. In its type locality the formation crops out on the southern flank of Nayband Mountain, about 200 km south of Tabas. It consists of a thick, mixed siliciclastic-carbonate sequence subdivided into four members; in ascending order: the Gelkan Member (mainly shales and silstones, the Bidestan Member (marls, siltstones with minor sandstones and fossiliferous limestones, the Howz-e-Sheikh Member (sandstones and siltstones, and the Howz-e-Khan Member (sponge and coral dominated reefs alternating with marls and sandstones. Three palynological assemblages have been recognised; in ascending order: a an assemblage characterised by the presence of Annulispora folliculosa and A. microannulata which allows the Gelkan Member and most of the Bidestan Member to be assigned an early Norian age; (b an assemblage marked by the first occurrence of Polycingulatisporites mooniensis, which indicates the upper part of the Bidestan Member is mid-late Norian; c an assemblage containing Classopollis chateaunovi in association with Retitriletes austroclavatidites, Gliscopollis meyeriana, Limbosporites lundbladii, Rugaletes awakinoensis and Callialasporites dampieri that allows the Howz-e-Sheikh Member to be assigned a Rhaetian age. The presence of some Eurasian and/or cosmopolitan forms in the Rhaetian microflora reflects the position of the Iranian plate on the southern margin of Eurasia.   

  7. Education and Training for Development in East Asia: The Political Economy of Skill Formation in East Asian Newly Industrialised Economies. ESRC Pacific Asia Programme [Series].

    Science.gov (United States)

    Ashton, David; Green, Francis; James, Donna; Sung, Johnny

    This book provides a detailed analysis of the development of education and training systems in Asia and the relationship with the process of economic growth. Focus is on four impoverished agrarian economies--Hong Kong, Singapore, South Korea, and Taiwan--that were transformed in little more than a generation into East Asian "tigers":…

  8. Ice Complex formation in arctic East Siberia during the MIS3 Interstadial

    Science.gov (United States)

    Wetterich, Sebastian; Tumskoy, Vladimir; Rudaya, Natalia; Andreev, Andrei A.; Opel, Thomas; Meyer, Hanno; Schirrmeister, Lutz; Hüls, Matthias

    2014-01-01

    A continuous 15 m long sequence of Ice Complex permafrost (Yedoma) exposed in a thermo-cirque at the southern coast of Bol'shoy Lyakhovsky Island (New Siberian Archipelago, Dmitry Laptev Strait) was studied to reconstruct past landscape and environmental dynamics. The sequence accumulated during the Marine Isotope Stage 3 (MIS3) Interstadial between >49 and 29 ka BP in an ice-wedge polygon. The frozen deposits were cryolithologically described and sampled on a vertical bluff between two ice wedges. According to sedimentological and geochronological data, the section is subdivided into three units which correlate with environmental conditions of the early, middle, and late MIS3 period. Palynological data support this stratification. The stable isotope signature of texture ice in the polygon structure reflects fractionation due to local freeze-thaw processes, while the signature of an approximately 5 m wide and more than 17 m high ice wedge fits very well into the regional stable-water isotope record. Regional climate dynamics during the MIS3 Interstadial and local landscape conditions of the polygonal patterned ground controlled the Ice Complex formation. The sequence presented here completes previously published MIS3 permafrost records in Northeast Siberia. Late Quaternary stadial-interstadial climate variability in arctic West Beringia is preserved at millennial resolution in the Ice Complex. A MIS3 climate optimum was revealed between 48 and 38 ka BP from the Ice Complex on Bol'shoy Lyakhovsky Island.

  9. Aerosol and CCN properties at Princess Elisabeth station, East Antarctica: seasonality, new particle formation events and properties around precipitation events

    Science.gov (United States)

    Mangold, Alexander; Laffineur, Quentin; De Backer, Hugo; Herenz, Paul; Wex, Heike; Gossart, Alexandra; Souverijns, Niels; Gorodetskaya, Irina; Van Lipzig, Nicole

    2016-04-01

    Since 2010, several complementary ground-based instruments for measuring the aerosol composition of the Antarctic atmosphere have been operated at the Belgian Antarctic research station Princess Elisabeth, in Dronning Maud Land, East Antarctica (71.95° S, 23.35° E, 1390 m asl.). In addition, three ground-based remote sensing instruments for cloud and precipitation observations have been installed for continuous operation, including a ceilometer (cloud base height, type, vertical extent), a 24 Ghz micro-rain radar (vertical profiles of radar effective reflectivity and Doppler velocity), and a pyrometer (cloud base temperature). The station is inhabited from November to end of February and operates under remote control during the other months. In this contribution, the general aerosol and cloud condensation nuclei (CCN) properties will be described with a special focus on new particle formation events and around precipitation events. New particle formation events are important for the atmospheric aerosol budget and they also show that aerosols are not only transported to Antarctica but are also produced there, also inland. Aerosols are essential for cloud formation and therefore also for precipitation, which is the only source for mass gain of the Antarctic ice sheet. Measured aerosol properties comprise size distribution, total number, total mass concentration, mass concentration of light-absorbing aerosol and absorption coefficient and total scattering coefficient. In addition, a CCN counter has been operated during austral summers 2013/14, 2014/15 and 2015/16. The baseline total number concentration N-total was around some hundreds of particles/cm3. During new particle formation events N-total increased to some thousands of particles/cm3. Simultaneous measurements of N-total, size distribution and CCN number revealed that mostly the number of particles smaller than 100 nm increased and that the concentration of cloud condensation nuclei increased only very

  10. Chapter 5. Assessment of undiscovered conventional oil and gas resources-Lower Cretaceous Travis Peak and Hosston formations, Jurassic Smackover interior salt basins total petroleum system, in the East Texas basin and Louisiana-Mississippi salt basins provinces.

    Science.gov (United States)

    Dyman, T.S.; Condon, S.M.

    2006-01-01

    The Lower Cretaceous Travis Peak Formation of east Texas and southern Arkansas (and the correlative Hosston Formation of Louisiana and Mississippi) is a basinward-thickening wedge of terrigenous clastic sedimentary rocks that underlies the northern Gulf of Mexico Basin from east Texas across northern Louisiana to southern Mississippi. Clastic detritus was derived from two main fluvial-deltaic depocenters, one in northeastern Texas and the other extending from southeastern Mississippi northwestward into northeastern Louisiana. Across the main hydrocarbon-productive trend in east Texas and northern Louisiana, the Travis Peak and Hosston Formations are about 2,000 ft thick.

  11. Holocene ice dynamics and bottom-water formation associated with Cape Darnley polynya activity recorded in Burton Basin, East Antarctica

    Science.gov (United States)

    Borchers, Andreas; Dietze, Elisabeth; Kuhn, Gerhard; Esper, Oliver; Voigt, Ines; Hartmann, Kai; Diekmann, Bernhard

    2016-03-01

    A multi-proxy study including sedimentological, mineralogical, biogeochemical and micropaleontological methods was conducted on sediment core PS69/849-2 retrieved from Burton Basin, MacRobertson Shelf, East Antarctica. The goal of this study was to depict the deglacial and Holocene environmental history of the MacRobertson Land-Prydz Bay region. A special focus was put on the timing of ice-sheet retreat and the variability of bottom-water formation due to sea ice formation through the Holocene. Results from site PS69/849-2 provide the first paleo-environmental record of Holocene variations in bottom-water production probably associated to the Cape Darnley polynya, which is the second largest polynya in the Antarctic. Methods included end-member modeling of laser-derived high-resolution grain size data to reconstruct the depositional regimes and bottom-water activity. The provenance of current-derived and ice-transported material was reconstructed using clay-mineral and heavy-mineral analysis. Conclusions on biogenic production were drawn by determination of biogenic opal and total organic carbon. It was found that the ice shelf front started to retreat from the site around 12.8 ka BP. This coincides with results from other records in Prydz Bay and suggests warming during the early Holocene optimum next to global sea level rise as the main trigger. Ice-rafted debris was then supplied to the site until 5.5 cal. ka BP, when Holocene global sea level rise stabilized and glacial isostatic rebound on MacRobertson Land commenced. Throughout the Holocene, three episodes of enhanced bottom-water activity probably due to elevated brine rejection in Cape Darnley polynya occured between 11.5 and 9 cal. ka BP, 5.6 and 4.5 cal. ka BP and since 1.5 cal. ka BP. These periods are related to shifts from warmer to cooler conditions at the end of Holocene warm periods, in particular the early Holocene optimum, the mid-Holocene warm period and at the beginning of the neoglacial. In

  12. Petrología y geoquímica de una ritmita marga-caliza del Hemisferio Austral: El Miembro Los Catutos (Formación Vaca Muerta, Tithoniano medio de la Cuenca Neuquina Petrology and geochemistry of a limestone-marl rhythmite from the Southern Hemisphere: the Los Catutos Member (Vaca Muerta Formation, Middle Tithonian of Neuquén Basin

    Directory of Open Access Journals (Sweden)

    R. A. Scasso

    2002-06-01

    abultamientos carbonáticos de baja pendiente en una rampa externa.A 25 m thick, rhythmic, limestone-marl alternation of Los Catutos Member (Vaca Muerta Formation, Neuquén Basin, was studied bed by bed in several quarries near Zapala. Beds up to 1 m thick are of massive or laminated, lithographic, fossiliferous limestone, locally mottled or weakly bioturbated (?Chondrites, interbedded with thinner marl beds. Limestones and marls can be classified as pelbiomicrites and biopelmicrites, mainly composed of pellets, radiolaria, forams, ostracods, equinoids, spicles of sponges and gastropods, with minor amounts of peloids, feldspar, chert, muscovite, glauconite and phosphates. Values for δ;;18O and δ;;13C are similar to those of lithographic limestones from the northern hemisphere. δ;;13O values are most probably result of diagenetic modification of the primary signal but the δ;;13C agrees well with the published curves for the Tithonian sea water and with other records from Tethyan limestones. A preliminary analysis of negative excursions of δ;;13C point to productivity crisis in the sedimentary system with a periodicity of 400 ka, which can be a result of changes in the orbital eccentricity of the earth. Smectite and interlayers reflect pedogenic processes developed on volcanogenic source-rocks, whereas more abundant kaolinite in marls might reflect more humid conditions. With TOC up to 1.95% the rocks offer prospects as a regular to good source rock for hydrocarbons, although thermally immature. A low-energy, dysaerobic, open-marine environment is inferred for Los Catutos Member, with high sedimentation rates as a result of high productivity at the sea-surface and incoming plumes of suspended sediment from the inner shelf. Sediment accumulation in wide and gently dipping calcareous bulges in an outer ramp system is envisaged.

  13. Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

    Institute of Scientific and Technical Information of China (English)

    FAN Qicheng; ZHANG Hongfu; SUI Jianli; ZHAI Mingguo; SUN Qian; LI Ni

    2005-01-01

    On the basis of mineral assemblage, mineralogy, petrology, and major, trace elemental and isotopic geochemistry of the underplated granulite- and eclogite-facies accumulate, peridotite and pyroxenite xenoliths entrained in Hannuoba Cenozoic basalts, this work constrained the petrological constituents for the crust-mantle transitional zone, which is supported by the results of high-temperature and pressure velocity experiments on rocks and geophysics deep survey. Present lower part of lower crust is mainly composed of granulite-facies mafic accumulates (dominantly plagioclase websterite) and crust-mantle transitional zone dominantly composed of eclogite-facies pyroxenites with or without garnet and spinel lherzolites; Archaean terrain granulite is only nominally early lower crust. Magma underplating in the crust-mantle boundary led to the crustal vertical accretion and the formation of the crust-mantle transitional zone, which is a significant mechanism for the chemical adjustment of the crust-mantle boundary since the Phanerozoic.

  14. Geology of the Lower Cretaceous Travis Peak Formation, East Texas. Depositional history, diagenesis, structure, and reservoir-engineering implications. Topical report, November 1982-February 1990

    Energy Technology Data Exchange (ETDEWEB)

    Dutton, S.P.; Laubach, S.E.; Tye, R.S.; Baumgardner, R.W.; Herrington, K.L.

    1990-06-01

    The report summarizes stratigraphic, petrographic, and structural studies of the Lower Cretaceous Travis Peak Formation, a low-permeability gas sandstone in East Texas, and presents reservoir engineering implications. Depositional systems in this region were interpreted from logs and cores and include (1) a braided- to meandering-fluvial system that forms the majority of the Travis Peak section; (2) deltaic deposits interbedded with the distal part of the fluvial system; (3) paralic deposits that overlie and interfinger with the deltaic and fluvial deposits near the top of the Travis Peak; and (4) shelf deposits present at the downdip extent of the formation. Petrographic studies indicate the sandstones are quartzarenites and subarkoses. Cementation by quartz, dolomite, ankerite, illite, chlorite, and reservoir bitumen have reduced porosity to less than 8 percent and permeability to less than 0.1 md throughout most of the formation. Structurally deeper sandstones are more intensely quartz cemented than are shallower sandstones and contain abundant, open natural fractures. Borehole breakouts and drilling-induced fractures in core can be used to predict horizontal stress directions and the direction of hydraulic fracture propagation. Hydraulic fractures propagate in directions subparallel to the east-northeast strike of the natural fractures; thus, hydraulically induced fractures may not intersect many natural fractures.

  15. A Digital Approach to Learning Petrology

    Science.gov (United States)

    Reid, M. R.

    2011-12-01

    In the undergraduate igneous and metamorphic petrology course at Northern Arizona University, we are employing petrographic microscopes equipped with relatively inexpensive ( $200) digital cameras that are linked to pen-tablet computers. The camera-tablet systems can assist student learning in a variety of ways. Images provided by the tablet computers can be used for helping students filter the visually complex specimens they examine. Instructors and students can simultaneously view the same petrographic features captured by the cameras and exchange information about them by pointing to salient features using the tablet pen. These images can become part of a virtual mineral/rock/texture portfolio tailored to individual student's needs. Captured digital illustrations can be annotated with digital ink or computer graphics tools; this activity emulates essential features of more traditional line drawings (visualizing an appropriate feature and selecting a representative image of it, internalizing the feature through studying and annotating it) while minimizing the frustration that many students feel about drawing. In these ways, we aim to help a student progress more efficiently from novice to expert. A number of our petrology laboratory exercises involve use of the camera-tablet systems for collaborative learning. Observational responsibilities are distributed among individual members of teams in order to increase interdependence and accountability, and to encourage efficiency. Annotated digital images are used to share students' findings and arrive at an understanding of an entire rock suite. This interdependence increases the individual's sense of responsibility for their work, and reporting out encourages students to practice use of technical vocabulary and to defend their observations. Pre- and post-course student interest in the camera-tablet systems has been assessed. In a post-course survey, the majority of students reported that, if available, they would use

  16. Petrology, mineral chemistry and tectono-magmatic setting of volcanic rocks from northeast Farmahin, north of Arak

    Directory of Open Access Journals (Sweden)

    Reza Zarei Sahamieh

    2014-10-01

    between magma and crustal rocks (Ghasemi and Talbot, 2006; Rollinson, 1993. Comparison of spider diagrams normalized to chondrite or MORB also show that the parent magma has been contaminated. It appears that assimilation and fractional crystallization (AFC were the dominant processes in the genesis of the studied volcanic rocks (Roozbehani and Arvin, 2010. As a conclusion and regarding to what we said in this article ,the area under study are included both lava and pyroclastic rocks such as andesite, dacite, rhyodacite, ignimbrite ,tuff and tuffits that cut by younger dykes and belong to Middle to Late Eocene age(middle Lutetian to upper Lutetian.There is no rocks older than Triassic age. Volcanic rocks have been occurred in two environments, dry and water together. From volumetric point of view, Aciditic and intermediate rocks such as dacite, rhyodacite and andesite are the most in the area under study (Ahmadian et al., 2010. Basitic rocks are a lesser amount than the others. Regarding to all evidences such as field works, structurally, texturally, mineralogically, geochemically and petrologically show that rocks in studied area belong to subduction zone and magma that created of these rocks have been originated from mantle and contaminated with continental crust during eruption and rising. Acknowledgments The authors wish to thank Journal Manager and reviewers who critically reviewed the manuscript and made valuable suggestions for its improvement. References Ahmadian, J., Bahadoran, N., Torabi, G. and Morata, M., 2010. Geochemistry and petrogenesis of volcanic rocks in Aroosan Kabood (north-east of Anarak. Journal of Petrology, 1(1: 103-120. (in Persian Ameri, A., ashrafi, N. and Karimi qarebaba, H., 2009. Petrology, Geochemistry and tectonics environment of Eocene volcanic rocks in east of Herris, east Azerbayjan, north-west of Iran. Journal of geosciences, 18(71: 85-90. (in Persian Ghasemi, A. and Talbot, C.J., 2006. A new scenario for the Sanandaj-Sirjan zone (Iran

  17. Formation of post-spreading volcanic ridges in the East sub-basin of the South China Sea

    Science.gov (United States)

    He, E.; Zhao, M.; Sibuet, J. C.; Tan, P.; Wang, J.; Qiu, X.

    2016-12-01

    In the South China Sea (SCS), the post-spreading magmatism ( 3-13 Ma) largely masks the initial seafloor spreading fabric. The resulting post-spreading seamounts are more numerous in the northern part than in the southern part of the East sub-basin. In the eastern part of the East sub-basin, the post-spreading volcanic ridge (PSVR) is approximately N055° oriented and follows the extinct spreading ridge (ESR). In the western part of the East sub-basin, the PSVR, called the Zhenbei-Huangyan seamounts chain, is E-W oriented and hides the ESR (Sibuet et al., 2016). We conducted a seismic refraction survey covering both the Zhenbei-Huangyan seamount chain and the location of the adjacent ESR. Three E-W oriented profiles and one N-S oriented profile are parallel and perpendicular to the Zhenbei-Huangyan seamounts chain, respectively. Our research is focused on the understanding of the relationship between the crustal thicknesses and crustal seismic velocities. The detailed velocity structure shows that the Zhenbei-Huangyan seamount chain was emplaced through a typical oceanic crust. Crustal thicknesses and seismic velocities suggest an asymmetric generation of seamounts in the East sub-basin, where active upwelling mantle (Holbrook et al., 2001) or buoyancy-driven decompression melting happened (Castillo et al., 2010). The Zhenbei and Huangyan seamounts were probably formed 3-5 Ma and 7-9 Ma, after seafloor spreading cessation; their thickened lower crusts were probably due to magmatic intrusions associated with a high-velocity layer (7.4-7.6 km/s),and their large thickness of upper crust were mainly due to volcanic extrusions. These two seamounts presents a different structural orientation and their crustal thicknesses are different, suggesting an independent origin for their magmatic feeding. This research was granted by the Natural Science Foundation of China (91428204, 91028002, 41176053).

  18. Petrological Study of High Island Formation volcanic columns in the Hong Kong National Geopark%香港国家地质公园粮船湾组火山岩岩石学研究

    Institute of Scientific and Technical Information of China (English)

    邢光福; 吴振扬; 陶奎元; 伍世良; 陈荣; 姜杨; 李龙明; 余明刚

    2011-01-01

    在香港国家地质公园西贡火山岩园区,核心地质景观是白垩纪粮船湾组(Kkh)火山岩优美的六方形石柱(柱状节理),它们的岩石类型长期存在熔岩和火山碎屑岩之争.笔者等经野外调查和薄片岩石学研究,确认粮船湾组火山岩实属一种特殊的熔岩——流纹质碎斑熔岩,以普遍的柱状节理、斑晶具有碎斑结构和珠边结构、基质发育霏细结构和流动构造为特征;它们不仅代表了香港地区中生代最晚期火山喷发的产物,而且构成了西贡破火山机构的中央侵出相岩穹.推断粮船湾组火山岩石柱是地球上已知面积最大的流纹质碎斑熔岩石柱群(~150 km2),目前所见的火山岩石柱仅是长期剥蚀后的残余部分.%Wonderful Hexagonal columns (columnar joints) of Cretaceous High Island Formation (Kkh) volcanic rocks make up the key landscape of the Sai Kung Volcanic Rock Region in southern Hong Kong National Geopark, but whether they belong to lava or pytoclastic rock has been thsputing. On the basis of field geological investigation and rock thin section observation, these volcanic rocks are determined to be a specific lava-rhyolidc porphyroclastic lava which is characterized by common columnar joints, porphyroclasdc & pearl -rim textures of phenocrysts, and felsitic texture & flow structure in groundmass. They are not only the latest Mesozoic products in Hong Kong but also constitute a large central extrusive fades dome within the Sai Kung Caldera. This porphyroclasdc lava dome is inferred to be the largest one (~150 km2) so far known in the world, and its residual parts after long-term erosion are current landscape which can be seen in the Sai Kung Volcanic Rock Region.

  19. Altering petrology through microbial dissimilatory phosphite oxidation

    Science.gov (United States)

    Zhu, H.; Figueroa, I.; Coates, J. D.

    2013-12-01

    Microbial enhanced oil recovery (MEOR) takes advantage of various microbial metabolisms to increase hydrocarbon and energy yield by improving oil flow and flood water sweep in a reservoir during tertiary recovery. Wormholing at the injection well is believed to be the result of the large drop in pressure when water exits the injection well and enters the unconsolidated reservoir matrix. One possible means of prevent this event is to consolidate the rock matrix immediately around the injection well to create a permeable zone of stable petrology. Many microbial processes are known to result in the precipitation of ionic components into their environment creating solid-phase minerals. Such processes could be judiciously applied to bind unconsolidated matrices in order to form a permeable concreted rock matrix, which would minimize wormholing events and thus improve floodwater sweep. However, to date, apart from the application of urea oxidation creating calcium carbonate precipitation, there has been little investigation of the applicability of these precipitated bioconcretions to MEOR strategies and none to control wormholing events. Here we present a novel approach to altering rock petrology to concrete unconsolidated matrices in the near well environment by the biogenesis of authigenic minerals through microbial dissimilatory phosphite oxidation. Desulfotignum phosphitoxidans, strain FiPS-3 is currently the only isolated organism capable of using phosphite (HPO32-) as an electron donor for growth. This process, known as dissimilatory phosphite oxidation (DPO), can be coupled to either sulfate reduction or homoacetogenesis and leads to the accumulation of inorganic phosphate in the medium. The resulting insoluble mineral phases can coat the rock environment resulting in a concretion binding the unconsolidated matrix particles into a single phase. In this study we demonstrate that DPO can effectively produce calcium or magnesium phosphate minerals in packed glass

  20. A Virtual Petrological Microscope for All Apollo 11 Lunar Samples

    Science.gov (United States)

    Pillnger, C. T.; Tindle, A. G.; Kelley, S. P.; Quick, K.; Scott, P.; Gibson, E. K.; Zeigler, R. A.

    2014-01-01

    A means of viewing, over the Internet, polished thin sections of every rock in the Apollo lunar sample collections via software, duplicaing many of the functions of a petrological microscope, is described.

  1. A virtual petrological microscope for teaching and outreach

    Science.gov (United States)

    Kelley, Simon P.; Whalley, Peter; Tindle, Andrew G.; Anand, Mahesh

    2010-05-01

    Learning to use microscopes for geoscience or life science applications is a crucial part of the practical training offered in many science degrees, but the opportunities to study are often constrained by available laboratory space and time, and sometimes constrained by the number of high quality microscopes available. The alternative, although not replacing physical microscopes, offers the opportunity for enhancement and enrichment of laboratory experience in geoscience. An on-line microscope can also be used to engage the public with access to rare rocks such as meteorites and lunar samples. The focus of petrological microscope study in higher education is not primarily related to learning facts but is concerned with learning how to discriminate and classify within the paradigms of the discipline. In this case, the recognition and measurement of key features in rock samples in hand specimen and thin section. Whilst undertaking the practical exercise of recognition and naming of rock samples students are really being required to develop an understanding of the rock cycle as a model representing the relationship between rock categories and the process of their formation. The problems of teaching with complex visual materials, in effect of teaching learners 'how to see' from the scientific perspective of a particular discipline, are quite general. It could reasonably be expected that lessons learnt from the implementation and detailed evaluation of the proposed web-based system will generalise to many other topics in science education. Thus we focussed on the thin section images rather than reproducing a system that resembled a physical microscope. The virtual petrological microscope developed for a course at the Open University UK enables student acquisition of skills such as mineral and rock recognition using a browser window to explore thin sections of rocks as if they were using a laboratory microscope. The microscope allows students to pan around the thin

  2. Petrology of Zircon-Bearing Diogenite Northwest Africa 10666

    Science.gov (United States)

    Tanner, T. B.; Jeffcoat, C. R.; Righter, M.; Berger, E. L.; Lapen, T. J.; Irving, A. J.; Kuehner, S. M.; Fujihara, G.

    2017-01-01

    The howardite, eucrite, and diogenite (HED) meteorites are a group of achondrites thought to be derived from the asteroid 4 Vesta, though there is active debate as to whether all diogenites are part of the HED suite. Petrologic investigation of the HED meteorite group provides a means of understanding early planetary differentiation processes and early evolution of planets in our solar system. Diogenites are predominantly coarse grained ortho-pyroxenites with some samples containing appreciable amounts of clinopyroxene, olivine, chromite, and plagioclase. Accessory metal, troilite, and apatite are common. Many diogenites are brecciated, however, there are few poorly to unbrecciated samples. Diogenites are important because they may represent the lower crust of 4 Vesta. Although Mg isotope data indicates that the sources of diogenites are ancient, their crystallization ages are difficult to constrain due to their protracted thermal histories. The limited chronologic data for diogenites also limits the ability to test petrogenetic connections with eucrites and even parent body. A reliable and high closure-temperature isotope system, such as U-Pb in zircon, is needed to address the timing of diogenite igneous crystallization. Description of the textures and mineralogy of diogenites are essential to their classification and understanding their formation, in particular, whether all phases are petrogenetically related. Here, we present detailed petrographic data from a rare zircon-bearing feldspathic diogenite, Northwest Africa (NWA) 10666 and provide textural evidence for igneous crystallization of the zircon.

  3. Petrology and stratigraphy of Paleogene nonmarine sandstones, Cascade Range, Washington

    Science.gov (United States)

    Frizzell, Virgil A.

    1979-01-01

    are important constituents of the Puget Group, the Chumstick and Naches Formations, and the isolated arkosic bodies. The three older units, however, contain relatively less volcanic lithics to total lithics than do younger units, indicating perhaps the initiation of more widespread volcanic activity in middle Eocene time. Ratios of framework grain parameters show that the terrestrial sandstone units were derived from a mixed plutonic and tectonic source terrane of continental block tectonic provenance with an overprint of magmatic arc provenance. Modal analysis was performed on samples from the various sedimentary units to establish petrologic compositions, and to provide data with which to compare the different units and discuss clast provenance and tectonic regimen. Although the arkosic sandstones have generally uniform framework clast compositions, minor yet significant differences do exist between the units. Basal or basement-onlap portions of the units in particular are locally derived and differ markedly from the overall compositions of the individual units. Many coincidences of composition, age, structure, and bedrock indicate that the Chuckanut and Swauk may have originally been deposited as a single unit that since has been offset approximately 160 kilometers by right lateral strike slip motion starting about 48 Ma. If this hypothetical offset did occur, then major movement on the Straight Creek Fault is bracketed between about 48 Ma and Oligocene time.

  4. Petrology and radiogeology of the Stripa pluton

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, Harold; Flexser, Steve; Andersson, Lennart

    1980-12-01

    To better define the character of the rock encompassing the thermomechanical and hydrological experiments at the Stripa mine in central Sweden, and to help determine the size of the Stripa pluton, detailed studies were conducted of the petrology and radiogeology of the quartz monzonite and adjacent rocks. Petrologic studies emphasized optical petrography, with supplementary X-ray diffraction, X-ray fluorescence and microprobe analyses. Radiogeologic investigations were based primarily on surface and underground gamma-ray spectrometric measurements of uranium, thorium and potassium, supplemented by laboratory gamma spectrometric analyses and fission-track radiographic determinations of the locations and abundance of uranium in the rock matrix. Both the quartz monzonite and the metavolcanic leptite which it intruded are strongly fractured. Two stages of fracture filling are evident; an earlier stage encompassing quartz, sericite, feldspar, epidote, and chlorite, and a later stage dominated by carbonate minerals. The Stripa quartz monzonite is chemically and mineralogically distinct from other plutons in the region. Muscovite is the predominant mica in the quartz monzonite; biotite has been altered to chlorite, hornblende is absent, and accessory minerals are scarce. In contrast, in other plutons in the Stripa region biotite and hornblende are prominent mafic minerals and accessory minerals are abundant. The Stripa quartz monzonite is also considerably more radioactive than the leptite and other plutons in the region. Uranium and thorium abundances are both- 30 ppm, considerably higher than in "normal" granitic rocks where the thorium-to-uranium ratio generally exceeds 2. Potassium-argon dating of muscovite from the Stripa quartz monzonite indicates that this rock may be older, at 1691 million years than granitic rock of the neighboring Gusselby and Kloten massifs, whose ages, based on K-Ar dating of biotite, are respectively 1604 and 1640 m.y. Heat flow and heat

  5. Formation of metamorphic core complexes in non-over-thickened continental crust: A case study of Liaodong Peninsula (East Asia)

    OpenAIRE

    Wang, Kun; Burov, Evgueni; Gumiaux, Charles; Chen, Yan; Lu, Gang; Mezri, Leila; Zhao, Liang

    2015-01-01

    International audience; Pre-thickened hot orogenic crust is often considered a necessary condition for the formation of continental metamorphic core complexes (MCCs). However, the discovery of MCCs in the Liaodong Peninsula, where the crust has a normal thickness (~ 35 km), challenges the universality of this scenario. Therefore, we implement a series of 2-D numerical thermo-mechanical modeling experiments in which we investigate the conditions of MCC formation in normal crusts, as well as th...

  6. Gas storage in salt formations in the Middle East. Prospects; Gasspeicherung in Salzformationen des Mittleren Ostens. Aussichten

    Energy Technology Data Exchange (ETDEWEB)

    Folle, Stefan; Schmidt, Uwe [StorConsult, Hannover (Germany)

    2012-07-01

    Compared to the saturated Central European gas market the Middle East has high development potential. This can be derived primarily from the increasing home demand and simultaneous supply obligations. Importing countries require the maintenance of stocks in order to be less dependent on price and political pressure. As production of energy sources in Israel is inadequate, for example, Egyptian natural gas is supplied. The same also applies to Jordan. This pipeline system is being planned as part of the supply to Europe via Turkey and has also been sabotaged several times. As a further example Iran as the fourth largest natural gas producer consumes a significant proportion of its gas production. The rapid population growth of the country and export obligations require the provision of storage space for the energy sources. The continuous realisation of underground storage facilities depends heavily on cooperation with the authorities. Because of the different approval procedures in each country it should be clarified which authorities must be consulted. In addition it should be checked how the authorities are linked to each other with regards to responsibility. In some countries a subordinate authority or municipality may cause abandonment of a major project, if in the case of cavern construction, for example, the water legislation is inadequately clarified and in arid areas agriculture is a competing user. The economical creation of a gas storage cavern depends in particular on the rock mechanical evaluation and the resulting optimised operation of the storage facility. The load-bearing behaviour of the saliniferous rock is determined essentially by its material properties and stresses. In the geotechnical stability analysis the stress and deformation states around cavities should be determined for the site-specific geological and utilisation conditions. Two examples of potential or planned gas storage projects in the Middle East are described in the contribution

  7. New constraints on the formation and evolution of the Andaman Sea, a sedimented back arc spreading center in the South East Asia, from seismic reflection studies.

    Science.gov (United States)

    Jourdain, A.; Singh, S. C.; Klinger, Y.

    2014-12-01

    The Andaman Sea is an enigmatic feature in the Indian Ocean region. To the west, it is bounded by a near arc parallel Andaman subduction system and to the east by the Malaya Peninsula. It hosts volcanic provinces like Alcock and Sewell Rises and the Andaman Sea Spreading Center (ASSC) that connects the sliver strike-slip Sagaing Fault in the north with the Andaman Nicobar and Great Sumatra Faults in the south. The actual spreading center follows a succession of basins, starting by the spreading of the Mergui basin in the south-east, 32 Ma ago, that shifted to the actual position of the spreading closer to the subduction trench. Several hypotheses have been proposed for the formation of the Andaman Sea basins: (a) Pull-apart basin along the Sagaing-Sumatra fault system, driven by the collision-extrusion mechanism and/or by the slip-partitioning induced by the oblique subduction, (b) Back-arc spreading due to the subduction. There is a debate about the orientation of the present spreading/extension between the North-South motion along the strike-slip faults and the NW-SE opening of the ASSC. We have access to 7000 km of high-resolution deep seismic reflection data, and high-resolution bathymetry data, which we combine with relocated earthquake data to shed light upon the formation and evolution of the Andaman Sea Basin. The central basin contains up to 4 km thick sediments. The crustal thickness is about 5-8 km in the central basin and increases to 13-15 km beneath the Alcock and Sewell Rises, which are devoid of sediments. Here we show how both the collision and the subduction play a role in the position and orientation of the extension in the Andaman Sea Basin, and how they influence the accretion at the spreading center.

  8. Stratigraphy and sedimentology of a basement-onlapping shallow marine sandstone succession, the Charcot Bugt Formation, Middle-Upper Jurassic, East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, M.; Piasecki, S. [Geological Survey of Denmark and Greenland, Copenhagen (Denmark)]. Geocenter; Surlyk, F. [Univ. of Copenhagen, Copenhagen (Denmark)]. Geological Inst.

    2003-07-01

    A rocky shore developed in early Middle Jurassic times by transgression of the crystalline basement in Milne'Land at the western margin of the East Greenland rift basin. The basement is onlapped by shallow marine sandstones of the Charcot Bugt Formation, locally with a thin fluvial unit at the base. The topography of the onlap surface suggests that a relative sea-level rise of at least 300 m took place in Early Bathonian - Middle Oxfordian times. The sea-level rise was punctuated by relative stillstands and falls during which progradation of the shoreline took place. Palynological data tied to the Boreal ammonite stratigraphy have greatly improved time resolution within the Charcot Bugt Formation, and the Jurassic succession in Milne Land can now be understood in terms of genetically-related depositional systems with a proximal to distal decrease in grain size. The sequence stratigraphic interpretation suggests that translation of the depositional systems governed by relative sea-level changes resulted in stacking of sandstone-dominated falling stage deposits in the Bastern, basinwards parts of Milne Land, whereas thick, remarkably coarsegrained transgressive systems tract deposits formed along the western basin margin. The bulk of the Charcot Bugt Formation consists of stacked sandstone-dominated shoreface units that prograded during highstands. The overall aggradational to backstepping stacking pattem recognised in the Charcot Bugt Formation is comparable to that in the contemporaneous Pelion Formation of the Jameson Land Basin and in correlative units of the mid-Norway shelf and the Northern North Sea. We suggest that the long-term evolution of the depositional systems may have been controlled by long-term eustatic rise acting in concert with relative sea-level changes reflecting regionally contemporaneous phases of rift initiation, dimax and gradual cessation of rifting. (au)

  9. The Aguilar pluton (23°12‧ S-65°40‧ W; NW Argentina): Petrological implications on the origin of the Late Jurassic intraplate magmatism in the Central Andes

    Science.gov (United States)

    Omarini, Ricardo H.; Gioncada, Anna; Vezzoli, Luigina; Mazzuoli, Roberto; Cristiani, Chiara; Sureda, Ricardo J.

    2013-11-01

    The Late Jurassic Aguilar pluton is located in NW Argentina, about 300-400 Km east of the Tarapacá basin, representing the backarc basin linked to the Jurassic volcanic arc. This small-size and compositionally heterogeneous pluton intruded the metasedimentary rocks of the Ordovician Santa Victoria Group, along the Cobres-Salinas Grandes lineament. A revision of published geochemical data in the light of new field and petrological results, allows us to propose a model concerning the petrogenesis and emplacement mechanisms of Aguilar pluton and to discuss its geodynamic setting. The pluton is mainly composed of metaluminous and nearly peraluminous granitoids, showing the geochemical characteristics of ferroan granites. The volumetrically subordinate mafic rocks are both ne- and hy-normative, and their primary magmas were generated by partial melting of a pristine Proterozoic mantle. Aguilar rocks display a rather limited range in (87Sr/86Sr)i, compared to the entire rift-related plutonic suite, i.e., 0.703198-0.704601, and ɛNdt from -1.06 to 3.82, calculated at 149 Ma. Fractional crystallization of mantle-derived magmas and crustal contamination processes explain the evolution to produce strongly silica-oversaturated magmas, which emplaced in the continental crust. The petrological data indicate that magma emplacement and cooling occurred at rather shallow depth. Multiple injections of magma batches into the magma chamber caused mingling and mixing processes early in the crystallization history. The Aguilar pluton is one of the several igneous complexes whose formation was associated with the extensional tectonics active during Late Jurassic-Early Cretaceous in NW Argentina. Based on the geological position and the igneous rocks affinity, we exclude that the Late Jurassic magmatism was generated in an orogenic setting and envisage that it was linked to the early extensional phase that preceded the Cretaceous continental rifting, related to the break-up of the South

  10. Incorporation of new particle formation and early growth treatments into WRF/Chem: Model improvement, evaluation, and impacts of anthropogenic aerosols over East Asia

    Science.gov (United States)

    Cai, Changjie; Zhang, Xin; Wang, Kai; Zhang, Yang; Wang, Litao; Zhang, Qiang; Duan, Fengkui; He, Kebin; Yu, Shao-Cai

    2016-01-01

    New particle formation (NPF) provides an important source of aerosol particles and cloud condensation nuclei, which may result in enhanced cloud droplet number concentration (CDNC) and cloud shortwave albedo. In this work, several nucleation parameterizations and one particle early growth parameterization are implemented into the online-coupled Weather Research and Forecasting model coupled with chemistry (WRF/Chem) to improve the model's capability in simulating NPF and early growth of ultrafine particles over East Asia. The default 8-bin over the size range of 39 nm-10 μm used in the Model for Simulating Aerosol Interactions and Chemistry aerosol module is expanded to the 12-bin over 1 nm-10 μm to explicitly track the formation and evolution of new particles. Although model biases remain in simulating H2SO4, condensation sink, growth rate, and formation rate, the evaluation of July 2008 simulation identifies a combination of three nucleation parameterizations (i.e., COMB) that can best represent the atmospheric nucleation processes in terms of both surface nucleation events and the resulting vertical distribution of ultrafine particle concentrations. COMB consists of a power law of Wang et al. (2011) based on activation theory for urban areas in planetary boundary layer (PBL), a power law of Boy et al. (2008) based on activation theory for non-urban areas in PBL, and the ion-mediated nucleation parameterization of YU10 for above PBL. The application and evaluation of the improved model with 12-bin and the COMB nucleation parameterization in East Asia during January, April, July, and October in 2001 show that the model has an overall reasonably good skill in reproducing most observed meteorological variables and surface and column chemical concentrations. Relatively large biases in simulated precipitation and wind speeds are due to inaccurate surface roughness and limitations in model treatments of cloud formation and aerosol-cloud-precipitation interactions

  11. Mercury: Informing Remote Sensing through Petrology in the Absence of Samples from the Innermost Planet

    Science.gov (United States)

    McCoy, T. J.; Nittler, L. R.; Stockstill-Cahill, K.; Blewett, D. T.

    2012-12-01

    Remote sensing missions and petrologic studies are complementary methods of understanding airless planetary bodies. For bodies with both orbital missions and samples available for laboratory study, missions provide global chemical, mineralogical, and geologic data sets and context for samples, whereas samples often provide complementary petrogenetic histories in a chronological framework. In contrast, although the wealth of orbital data from MESSENGER is not complemented by samples from Mercury, petrologic and experimental studies remain essential to understanding the innermost planet. Prior to MESSENGER, most models centered on high-temperature events and formation under highly reducing conditions to explain Mercury's high metal to silicate ratio. These models predicted enrichment in refractory elements and depletion in volatile elements. The inference of formation at highly reducing conditions is supported by MESSENGER results. The low FeO concentration in the crust, implied low FeO contents of the mantle, apparent efficient partitioning of iron into the core, and evidence for Ca- and/or Mg-sulfides from X-Ray Spectrometer data are all consistent with reducing conditions. In contrast, the suggestion that Mercury is highly volatile-depleted has been refuted. Direct evidence for a relatively volatile-rich planet come from Na, K, and S abundances measured on the surface with MESSENGER's XRS and Gamma-Ray Spectrometer and the presence of neutral and ionized Na, K, and S species in the exosphere. Indirect evidence for volatile-rich compositions include the suggestion of volcanic vents with associated mantling pyroclastic deposits, hollows inferred to form by geologically recent volatile loss, and an inferred interior structure that includes a solid iron sulfide layer at the top of Mercury's fluid core. Petrologic and experimental studies of meteorites have played a key role in deciphering orbital data from MESSENGER. Partial melts from an enstatite chondrite

  12. Spatial and temporal variations of new particle formation in East Asia using an NPF-explicit WRF-chem model: North-south contrast in new particle formation frequency

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, H.; Koike, Makoto; Takegawa, Nobuyuki; Kondo, Yutaka; Takami, A.; Takamura, T.; Yoon, Soh-joung; Kim, S. W.; Lim, Hyuntae; Fast, Jerome D.

    2013-10-27

    The new particle formation (NPF)-explicit version of the WRF-chem model, which we developed recently, can calculate the growth and sink of nucleated clusters explicitly with 20 aerosol size bins from 1 nm to 10 μm. In this study, the model is used to understand spatial and temporal variations of the frequency of NPF events and the concentrations of aerosols (condensation nuclei, CN) and cloud condensation nuclei (CCN) within the boundary layer in East Asia in spring 2009. Model simulations show distinct north-south contrast in the frequency and mechanism of NPF in East Asia. NPF mostly occurred over limited periods and regions between 30° and 45°N, such as northeast China, Korea, and Japan, including regions around active volcanoes (Miyakejima and Sakurajima). At these latitudes, NPF was considerably suppressed by high concentrations of preexisting particles under stagnant air conditions associated with high-pressure systems, while nucleation occurred more extensively on most days during the simulation period. Conversely, neither nucleation nor NPF occurred frequently south of 30°N because of lower SO2 emissions and H2SO4 concentrations. The period-averaged NPF frequency was 3 times higher at latitudes of 30° - 45°N than at latitudes of 20° - 30°N. The north-south contrast of NPF frequency is validated by surface measurements in outflow regions in East Asia. The period- and domain-averaged contribution of secondary particles is estimated to be 44% for CN (> 10 nm) and 26% for CCN at a supersaturation of 1.0% in our simulation, though the contribution is highly sensitive to the magnitudes and size distributions of primary aerosol emissions and the coefficients in the nucleation parameterizations.

  13. Spatial and temporal variations of new particle formation in East Asia using an NPF-explicit WRF-chem model: North-south contrast in new particle formation frequency

    Science.gov (United States)

    Matsui, H.; Koike, M.; Takegawa, N.; Kondo, Y.; Takami, A.; Takamura, T.; Yoon, S.; Kim, S.-W.; Lim, H.-C.; Fast, J. D.

    2013-10-01

    recently developed new particle formation (NPF)-explicit version of the Weather Research and Forecasting Chemistry (WRF-chem) model can explicitly calculate the growth and sink of nucleated clusters with 20 aerosol size bins from 1 nm to 10 µm in diameter. In this study, the model was used to investigate spatial and temporal variations in NPF event frequency and the concentrations of aerosols (condensation nuclei, CN) and cloud condensation nuclei (CCN) within the boundary layer in East Asia in spring 2009. We found a distinct north-south contrast in the NPF frequency and mechanism in East Asia. NPF occurred mainly during limited periods over certain regions between 30° and 45°N (northeast China, Korea, and Japan, including regions around the active volcanoes Miyakejima and Sakurajima). In these latitudes, NPF was suppressed by high concentrations of preexisting particles under stagnant air conditions associated with high-pressure systems, although nucleation occurred more extensively during most of the simulation period. In contrast, south of 30°N, nucleation and NPF were both infrequent because of low SO2 emissions and H2SO4 concentrations. The period-averaged NPF frequency at 30°-45°N was three times that at 20°-30°N. This north-south contrast in NPF frequency was validated by surface measurements in outflow regions of East Asia. The simulated period- and domain-averaged contribution of secondary particles was estimated to be 44% for CN (>10 nm) and 26% for CCN at a supersaturation of 1.0%, though the contribution was highly sensitive to the amount and size distribution of primary aerosol emissions and the rate coefficient of the nucleation parameterization.

  14. On the Basic Principles of Igneous Petrology

    Science.gov (United States)

    Marsh, B. D.

    2014-12-01

    How and why Differentiation occurs has dominated Igneous Petrology since its beginning (~1880) even though many of the problems associated with it have been thoroughly solved. Rediscovery of the proverbial wheel with new techniques impedes progress. As soon as thin section petrography was combined with rock and mineral chemistry, rock diversity, compositional suites, and petrographic provinces all became obvious. The masterful 1902 CIPW norm in a real sense solved the chemical mystery of differentiation: rocks are related by the addition and subtraction of minerals in the anciently appreciated process of fractional crystallization. Yet few believed this, even after phase equilibria arrived. Assimilation, gas transfer, magma mixing, Soret diffusion, immiscibility, and other processes had strong adherents, even though by 1897 Becker conclusively showed the ineffectiveness of molecular diffusion in large-scale processes. The enormity of heat to molecular diffusion (today's Lewis no.) should have been convincing; but few paid attention. Bowen did, and he refined and restated the result; few still paid attention. And in spite of his truly masterful command of experiment and field relations in promoting fractional crystallization, Fenner and others fought him with odd arguments. The beauty of phase equilibria eventually dominated at the expense of knowing the physical side of differentiation. Bowen himself saw and struggled with the connection between physical and chemical processes. Progress has come from new concepts in heat transfer, kinetics, and slurry dynamics. The key approach is understanding the dynamic competition between spatial rates of solidification and all other processes. The lesson is clear: Scholarship and combined field, laboratory and technical expertise are critical to understanding magmatic processes. Magma is a limitlessly enchanting and challenging material wherein physical processes buttressed by chemistry govern.

  15. Provenance records of the North Jiangsu Basin,East China:Zircon U-Pb geochronology and geochemistry from the Paleogene Dainan Formation in the Gaoyou Sag

    Institute of Scientific and Technical Information of China (English)

    Chun-Ming; Lin; Xia; Zhang; Ni; Zhang; Shun-Yong; Chen; Jian; Zhou; Yu-Rui; Liu

    2014-01-01

    Detailed zircon U-Pb dating and whole-rock geochemical analyses were carried out on the sedimentary rocks of the Paleogene Dainan Formation from Gaoyou Sag in the North Jiangsu Basin,East China.Whole-rock rare earth element characteristics suggest that the provenance was mainly from the Late Proterozoic low-grade metamorphic felsic rocks in the Dabie-Sulu orogenic belt,with the parent rocks probably being the I-type high-potassium granite gneiss.Cathodoluminescence images indicate that most of the detrital zircons are originally magmatic.A few zircons show overgrowths,indicating multiple-episode tectonic events.The U-Pb age distribution patterns of the detrital zircons suggest four main magmatic episodes in the provenance:Late Archean-Early Proterozoic(2450-2600 Ma),Early Proterozoic(1700-1900 Ma),Late Proterozoic(700-850 Ma),and Late Paleozoic-Mesozoic(100-300 Ma).These zircon U-Pb age and whole-rock geochemical results suggest that the sediments of the Dainan Formation were mainly sourced from the recycled orogenic belts within and/or around the North Jiangsu Basin,including the basement of the Yangtze Block,the Neoproterozoic rocks in the Dabie-Sulu orogenic belt,and the Mesozoic igneous rocks in the south part of Zhangbaling Uplift.

  16. Blending Curriculum with Research in an Undergraduate Petrology Course: A Recipe for Success?

    Science.gov (United States)

    Gonzales, D. A.; Semken, S. C.

    2009-12-01

    In this presentation we discuss the design, key curricular elements, and strengths and weaknesses of an undergraduate course in the Department of Geosciences at Fort Lewis College that was recast to focus on petrologic studies in the Southern Rocky Mountains and Colorado Plateau. Redesign of the course retained an additional petrology option in the curriculum and offered undergraduates a richer opportunity to learn and practice science-research skills. This course emphasizes direct engagement and student responsibility for learning: traits valuable in transforming undergraduates into experienced and competent professionals. Previous offerings of this course have been field based, each having a unique context for research. The primary pedagogical strategy was to blend field studies with inquiry to promote authentic, student-driven research. Students applied and tested their prior knowledge, and used observational and interpretative skills, to investigate major regional rock bodies and geologic histories, as opposed to completing a set of activities with predefined outcomes. In 2010, students will work on an NSF-funded project to test hypotheses on the origin and evolution of mafic magmas of the Navajo volcanic field. This research will most involve petrographic and microanalytical techniques on rock specimens with a subordinate amount of field work. Formative and summative assessment data for previous offerings of this course reveal that these classes have an impact on the academic interests and future successes of students. Assessment data collected from students, and other faculty that interacted with them, indicate that students in this research-oriented petrology course have gained a greater understanding of the elements and complications of research. They have also developed geologic skills and a passion for geologic research that have influenced subsequent academic (and later career) paths of the students.

  17. The formation of lacustrine dolomites: an example from the Tortonian-Messinian sequence at the East Mediterranean margins (northern Israel)

    Science.gov (United States)

    Shaked Gelband, Dotan; Starinsky, Abraham; Stein, Mordechai

    2017-04-01

    Lacustrine water bodies that filled the tectonic depressions in the Lower Galilee area of Israel during the Tortonian-Messinian periods deposited Bira and Gesher Formations, which comprise marly limestones and dolomites, basalts, and varying amounts of mollusc fossils. Most fossils are gastropods of fresh to brackish water origin, while marine representation is minor and comprise monospecific assemblages of euryhaline bivalves. During the deposition of the Tortonian Bira formation the lakes were mostly influenced by meteoric waters while during the deposition of the Messinian Gesher Formation they became more swampy. Here, we set to establish the deposition conditions of the dolomites in the lacustrine formations. The following petrographic characteristics indicate dolomitization of precursor carbonate sediment during early diagenesis stage: (1) Dolomitized fossils with similar texture as the surrounding dolomite matrix; (2) Common euhedral inner zone crystals, representing original growth in solution or plastic environment; (3) Subhedral outer shape derived from neighboring crystals collisions. More information is given by the δ18O and δ13C values of the dolomites. The δ18O of the inter-layered limestones and dolomites fluctuates between -3‰ to -4‰ (VPDB) in the limestones and +5‰ to -1.5‰ (VPDB) in the adjacent dolomites. These fluctuations are prominent in the Bira formation and become smaller along the sequence with the decrease in the dolomite values. δ13C values of both limestones and dolomites gradually decrease along the stratigraphic section, from -3.5‰ to -10‰ (VPDB) in the limestones, and from 0‰ to -8‰ (VPDB) in the dolomites. The data suggest a dolomitization process controlled by the following events: 1. Evaporation of fresh lake waters originated from the surrounding environment as runoff. It should be emphasized that significant evaporation could take place only in terminal lakes, during periods of relatively dry climate with low

  18. Diagenesis and porosity evolution of sandstone reservoirs in the East Ⅱ part of Sulige gas field, Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    Yang Renchao; Fan Aiping; Han Zuozhen; Wang Xiuping

    2012-01-01

    It is becoming an important controlling factor of gas exploration and exploitation in the east part of Sulige gas field in the Ordos Basin where the reservoir of main gas formations is tight sandstones.Employing experimental methods of slice identification,casting slice,scan electron microscope,and X-ray diffractions,we studied the characteristics of petrology and diagenesis on reservoirs in Shan1 section of Shanxi formation and He8 section of Shihezi formation of the Permian system in the East Ⅱ part of Sulige gas field.The results include:(1) the main sandstones in these areas are dominated by lithic sandstone and lithic silicarenite with low grade of maturity; (2) the diagenesis of sandstone in these areas mainly include compaction,cementation,corrosion and alteration.Conclusions are as follows:(1) the diagenetic stage reached period B of the middle diagenetic stage; (2) the early diagenetic compaction is one of the main factors to decreasing porosity:(3) the secondary pores formed by corrosion in acidity medium conditions in period A of the middle diagenetic stage can distinctly ameliorate the poor reservoir capability of sandstone and; (4) cementation in period B of the middle diagenetic stage is the most important factor leading to poor physical property of sandstone reservoirs.

  19. Seismic sedimentology of conglomeratic sandbodies in lower third member of Shahejie Formation (Palaeogene) in Shengtuo area, East China

    Institute of Scientific and Technical Information of China (English)

    袁勇; 张金亮; 李存磊; 孟宁宁; 李岩

    2014-01-01

    The sand-conglomerate fans are the major depositional systems in the lower third member of Shahejie Formation in Shengtuo area, which formed in the deep lacustrine environment characterized by steep slope gradient, near sources and intensive tectonic activity. This work was focused on the sedimentary feature of the glutenite segment to conduct the seismic sedimentology research. The near-shore subaqueous fans and its relative gravity channel and slump turbidite fan depositions were identified according to observation and description of cores combining with the numerous data of seismic and logging. Then, the depositional model was built depending on the analysis of palaeogeomorphology. The seismic attributes which are related to the hydrocarbon but relative independent were chosen to conduct the analysis, the reservoir area of the glutenite segment was found performing a distribution where the amplitude value is relatively higher, and finally the RMS amplitude attribute was chosen to conduct the attribute predicting. At the same time, the horizontal distribution of the sedimentary facies was analyzed qualitatively. At last, the sparse spike inversion method was used to conduct the acoustic impedance inversion, and the inversion result can distinguish glutenite reservoir which is greater than 5 m. This method quantitatively characterizes the distribution area of the favorable reservoir sand.

  20. Shale gas characterization of the Dinder and Blue Nile Formations in the Blue Nile Basin, East Sudan

    Science.gov (United States)

    Shoieb, Monera Adam; Sum, Chow Weng; Bhattachary, Swapan Kumar; Abidin, Nor Syazwani Zainal; Abdelrahim, Omer Babiker

    2016-11-01

    The development of gas and oil in unconventional plays in United State and Northern Europe has affected the finances and the energy security. Geochanical properties of shale rocks can have a major impact on the efficiency of shale gas exploration. The goal of this study is to evaluate shale gas potentiality in the Blue Nile Basin, using samples from existing drilled wells. All the samples were analyzed in detail with the following organic geochemical techniques: total organic carbon (TOC), Rock-eval pyrolysis, to determine the quality and quantity of the organic matter. The total organic carbon (TOC) values for the shale intervals vary from 0.6 to 4.5weight% in FARASHA-1 Well, while in TAWAKUL-1 Well range from 0.4 to 2.4weight%, suggesting that fair to good source generative potential, as revealed by the S2 v's TOC plot. Hydrogen index (HI) values range from 12 to 182 mg HC/g TOC in the two wells, indicating type III and IV derived-input in the samples and their potential to generate gas. However, the Blue Nile and Dinder Formation have Tmax values in the range of 437 to 456°C, indicating early maturity in the oil window. Thus, higher maturity levels have affected the hydrocarbon generation potential and HI of the samples.

  1. Depositional evolution of a reef-dominated Upper Permian carbonate platform, Wegener Halvoe Formation, Karstryggen area, East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Stemmrik, L.

    1996-12-31

    The Wegener Halvoe Formation carbonate platform in the Karstryggen area consists of three third order depositional sequences that formed in response to three Kazanian sea level cycles. Pinning point curves for the sub-aerial exposure surfaces separating the depositional sequences quantify the amplitude of the relative sea level fluctuations in the range of 70-140 m. The Karstryggen platform developed on top of a karstified older Permian carbonate platform and pre-depositional relief was locally exceeding 70 m. The pre-depositional relief influenced deposition in all three sequences. Algal-cement buildups formed over karst pinnacles and merged during time to form a N-S trending barrier dissected by deep fluvially modified karst channels. Peritidal carbonates formed behind the barrier whereas off platform sedimentation was dominated by thin transgressive siliciclastics overlain by shallow marine algal-foraminifer grain-stones in the first two sequences. During the last sea level cycle pro-grading oolitic grain-stones formed basin-wards of the algal-cement buildups. Transgressive systems tracts are thin and often dominated by condensed siliciclastic units in off platform areas and palaeolows. Over palaeotopographic highs it consists of aggrading algal cement-stones. High-stand deposits are limited to palaeotopographic elevated areas and consist of algal cementstones along the basin margin and shallow sub-tidal to inter-tidal carbonates and evaporites in the platform area. Outside these areas carbonate deposition took place during falling sea level, and during deposition of the first two sequences thin laterally extensive units of shallow marine grain-stones were deposited directly on top of deeper marine siliciclastics. During the final sea level fall, thick pro-grading units of oolitic grain-stones were deposited. (au) Appendix no. 3. 28 refs.

  2. Formation processes of sea ice floe size distribution in the interior pack and its relationship to the marginal ice zone off East Antarctica

    Science.gov (United States)

    Toyota, Takenobu; Kohout, Alison; Fraser, Alexander D.

    2016-09-01

    To understand the behavior of the Seasonal Ice Zone (SIZ), which is composed of sea-ice floes of various sizes, knowledge of the floe size distribution (FSD) is important. In particular, FSD in the Marginal Ice Zone (MIZ), controlled by wave-ice interaction, plays an important role in determining the retreating rates of sea-ice extent on a global scale because the cumulative perimeter of floes enhances melting. To improve the understanding of wave-ice interaction and subsequent effects on FSD in the MIZ, FSD measurements were conducted off East Antarctica during the second Sea Ice Physics and Ecosystems eXperiment (SIPEX-2) in late winter 2012. Since logistical reasons limited helicopter operations to two interior ice regions, FSD in the interior ice region was determined using a combination of heli-photos and MODIS satellite visible images. The possible effect of wave-ice interaction in the MIZ was examined by comparison with past results obtained in the same MIZ, with our analysis showing: (1) FSD in the interior ice region is basically scale invariant for both small- (large- (>1 km) scale regimes; (2) although fractal dimensions are quite different between these two regimes, they are both rather close to that in the MIZ; and (3) for floes <100 m in diameter, a regime shift which appeared at 20-40 m in the MIZ is absent. These results indicate that one role of wave-ice interaction is to modulate the FSD that already exists in the interior ice region, rather than directly determine it. The possibilities of floe-floe collisions and storm-induced lead formation are considered as possible formation processes of FSD in the interior pack.

  3. Formation and evolution of the modem warm current system in the East China Sea and the Yellow Sea since the last deglaciation

    Institute of Scientific and Technical Information of China (English)

    LI Tiegang; NAN Qingyun; JIANG Bo; SUN Rongtao; ZHANG Deyu; LI Qing

    2009-01-01

    To reconstruct the formation and evolution process of the warm current system within the East China Sea (ECS) and the Yellow Sea (YS) since the last deglaciation, the paleoceangraphic records in core DGKS9603, core CSH1 and core YSDPI02, which were retrieved from the mainstream of the Kuroshio Current (KC), the edge of the modem Tsushima Warm Current (TWC) and muddy region under cold waters accreted with the Yellow Sea Warm Current (YSWC) respectively, were synthetically analyzed. The results indicate that the formation and evolution of the modem warm current system in the ECS and the YS has been accompanied by the development of the KC and impulse rising of the sea level since the last deglaciation. The influence of the KC on the Okinawa Trough had enhanced since 16 cal kyr BE and synchronously the modem TWC began to develop with the rising of sea level and finally formed at about 8.5 cal kyr BP. The KC had experienced two weakening process during the Heinrich event 1 and the Younger Drays event from 16 to 8.5 cal kyr BP. The period of 7-6 cal kyr BP was the strongest stage of the KC and the TWC since the last deglaciation. The YSWC has appeared at about 6.4 cal kyr BP. Thus,the warm current system of the ECS and the YS has ultimately formed. The weakness of the KC,indicated by the occurrence of Pulleniatina minimum event (PME) during the period from 5.3 to 2.8 cal kyr BE caused the main stream of the TWC to shift eastward to the Pacific Ocean around about 3 cal kyr BP. The process resulted in the intruding of continent shelf cold water mass with rich nutrients. Synchronously, the strength of the YSWC was relatively weak and the related cold water body was active at the early-mid stage of its appearance against the PME background, which resulted in the quick formation of muddy deposit system in the southeastern YS. The strength of the warm current system in the ECS and the YS has enhanced evidently, and approached to the modern condition gradually since 3 cal kyr

  4. Petrology and petrogenesis of the Eocene Volcanic rocks in Yildizeli area (Sivas), Central Anatolia, Turkey

    Science.gov (United States)

    Doğa Topbay, C.; Karacık, Zekiye; Genç, S. Can; Göçmengil, Gönenç

    2015-04-01

    Yıldızeli region to the south of İzmir Ankara Erzincan suture zone is situated on the large Sivas Tertiary sedimentary basin. After the northern branch of the Neotethyan Ocean was northerly consumed beneath the Sakarya Continent, a continent - continent collision occurred between the Anatolide- Tauride platform and Pontides and followed a severe intermediate magmatism during the Late Cretaceous- Tertiary period. This created an east-west trending volcanic belt along the whole Pontide range. In the previous studies different models are suggested for the Eocene volcanic succession such as post-collisional, delamination and slab-breakoff models as well as the arc model for its westernmost parts. We will present our field and geochemical data obtained from the Yıldızeli and its surroundings for its petrogenesis, and will discuss the tectonic model(s) on the basis of their geochemical/petrological aspects. Cenozoic volcanic sequences of Yıldızeli region which is the main subject of this study, overlie Pre-Mesozoic crustal meta-sedimentary group of Kırşehir Massif, Ophiolitic mélange and Cretaceous- Paleocene? flysch-like sequences. In the northern part of Yıldızeli region, north vergent thrust fault trending E-W seperates the ophiolitic mélange complex from the Upper Cretaceous-Paleocene and Tertiary formations. Volcano-sedimentary units, Eocene in age, of the Yıldızeli (Sivas-Turkey) which are intercalated with sedimentary deposits related to the collision of Anatolide-Tauride and a simultaneous volcanic activity (i.e. the Yıldızeli volcanics), exposed throughout a wide zone along E-W orientation. Yıldızeli volcanics consist of basalts, basaltic-andesites and andesitic lavas intercalated flow breccias and epiclastic, pyroclastic deposits. Basaltic andesite lavas contain Ca-rich plagioclase + clinopyroxene ± olivine with minor amounts of opaque minerals in a matrix comprised of microlites and glass; andesitic lavas are generally contain Ca

  5. Volcanismo calcoalcalino neopaleozoico en la Precordillera de La Rioja. Petrología y caracterización litoestratigráfica de la Formación Punta del Agua (Carbonífero Superior-Pérmico Inferior Late Palaeozoic calc-alkaline volcanism in the Precordillera of La Rioja: petrology and lithostratigraphical characterization of the Punta del Agua Formation (Late Carboniferous - Early Permian

    Directory of Open Access Journals (Sweden)

    M. Remesal

    2004-09-01

    Full Text Available La Formación Punta del Agua en el extremo noroccidental de la cuenca Paganzo, representa las primeras manifestaciones de actividad volcánica neopaleozoica en la Precordillera y en las Sierras Pampeanas. La variedad litológica de esta unidad comprende interestratificación de flujos lávicos, flujos piroclásticos y acumulaciones sedimentarias. Los flujos lávicos fueron divididos según su composición y textura; se incluyó en esta agrupación un filón capa de composición dacítica. Los flujos piroclásticos fueron subdivididos para su caracterización en depósitos gruesos de flujos de bloques y cenizas y reoignimbritas. Durante los períodos intereruptivos tuvo lugar la sedimentación de conglomerados volcánicos, arenitas líticas volcánicas y escasos niveles pelíticos; todas estas rocas conforman litosomas fuertemente lenticulares que reflejan la irregularidad morfológica del campo volcánico. Las características geoquímicas de las volcanitas fueron analizadas sobre la base de doce muestras provenientes de ambos flancos del sinclinal de Punta del Agua. Los valores obtenidos corresponden al espectro de rocas mesosilíceas y ácidas, desde andesitas basálticas hasta riolitas, aunque claramente dominan las composiciones andesíticas. El carácter calcoalcalino de estas rocas, y la abundancia relativa en K de las andesitas, sugieren líquidos padres originados en zonas de subducción con efectos de procesos de cristalización fraccionada y contaminación sobreimpuestos. En lo que corresponde a la antigüedad de la unidad ha sido establecida a partir de sus relaciones estratigráficas y dataciones radimétricas; ambas líneas de investigación sugieren una edad carbonífera superior para el conjunto, aunque sin descartar que sus términos cuspidales alcancen el Pérmico más temprano.The Punta del Agua Formation (north-west Paganzo Basin represents the earliest manifestation of Neopalaeozoic volcanism in the Precordillera and Sierras

  6. Petrologic comparisons of Cayley and Descartes on the basis of Apollo 16 soils from stations 4 and 11

    Science.gov (United States)

    Basu, A.; Mckay, D. S.

    1984-01-01

    Petrologic aspects of the Cayley and Descartes formations are reviewed in the light of new data on Apollo 16 soils. Specific comparison of the modal abundances of lithic fragments in drive tube sample 64001/2 from the slopes of Stone Mountain (station 4) and in soil 67941 from the North Ray Crater rim (station 11) shows that melt rocks, especially poikilitic rocks, are more abundant at station 4 than at station 11; the reverse is true for fragmental breccias. Such lithologic differences suggest that stations 4 and 11 do not belong to the same geologic formation. Metamorphosed breccias are pervasive in both the formations and may represent a local component that has been reworked and diluted as fresh materials were added. Lithologic compositions inferred from the study of soil samples are different from lithologic compositions inferred from the study of rake samples or breccia clasts. This difference may be related to a mixing of material of different grain size distributions. The petrology of soils at the Apollo 16 site may not accurately reflect original material associated with either the Descartes or the Cayley formation because of extensive mixing with local material.

  7. Formation of Si-Al-Mg-Ca-rich zoned magnetite in an end-Permian phreatomagmatic pipe in the Tunguska Basin, East Siberia

    Science.gov (United States)

    Neumann, Else-Ragnhild; Svensen, Henrik H.; Polozov, Alexander G.; Hammer, Øyvind

    2017-03-01

    Magma-sediment interactions in the evaporite-rich Tunguska Basin resulted in the formation of numerous phreatomagmatic pipes during emplacement of the Siberian Traps. The pipes contain magnetite-apatite deposits with copper and celestine mineralization. We have performed a detailed petrographic and geochemical study of magnetite from long cores drilled through three pipe breccia structures near Bratsk, East Siberia. The magnetite samples are zoned and rich in Si (≤5.3 wt% SiO2), Ca, Al, and Mg. They exhibit four textural types: (1) massive ore in veins, (2) coating on breccia clasts, (3) replacement ore, and (4) reworked ore at the crater base. The textural types have different chemical characteristics. "Breccia coating" magnetite has relatively low Mg content relative to Si, as compared to the other groups, and appears to have formed at lower oxygen fugacity. Time series analyses of MgO variations in microprobe transects across Si-bearing magnetite in massive ore indicate that oscillatory zoning in the massive ore was controlled by an internal self-organized process. We suggest that hydrothermal Fe-rich brines were supplied from basalt-sediment interaction zones in the evaporite-rich sedimentary basin, leading to magnetite ore deposition in the pipes. Hydrothermal fluid composition appears to be controlled by proximity to dolerite fragments, temperature, and oxygen fugacity. Magnetite from the pipes has attributes of iron oxide-apatite deposits (e.g., textures, oscillatory zoning, association with apatite, and high Si content) but has higher Mg and Ca content and different mineral assemblages. These features are similar to magnetite found in skarn deposits. We conclude that the Siberian Traps-related pipe magnetite deposit gives insight into the metamorphic and hydrothermal effects following magma emplacement in a sedimentary basin.

  8. Facies analysis of the Balta Formation: Evidence for a large late Miocene fluvio-deltaic system in the East Carpathian Foreland

    Science.gov (United States)

    Matoshko, Anton; Matoshko, Andrei; de Leeuw, Arjan; Stoica, Marius

    2016-08-01

    Deposits of the Balta Fm are preserved in a large arcuate sediment body that covers about 60,000 km2 and is up to 350 m thick. The Balta Fm spans ca. 5 Ma as constrained by underlying Tortonian (Bessarabian) and overlying Messinian (early Pontian) Paratethys strata. It contains frequent terrestrial mammal fossils and fresh- as well as brackish-water (Paratethys) molluscs and ostracods. Over the past 140 years our understanding of the sedimentary architecture of the formation and its origins has remained in its infancy, which has limited insight into the evolution of the East Carpathian Foreland. Here, we provide the first modern sedimentary facies analysis of the Balta Fm, which is integrated with an extensive review of previously published local literature. It is supported with micropalaeontological results and a wealth of historical borehole information. We show that the Balta Fm has a tripartite vertical division. Its lowermost part is clay dominated and consists of subordinate delta front sand bodies interspersed between muds. The middle unit contains separate delta plain channels or channel belts encased in thick muds. These are overlain by a unit with amalgamated delta plain channel deposits with only minor amounts of associated mud. The abundance of upper flow regime sedimentary structures in channel sands, the absence of peats (or coals) and the presence of calcareous nodules suggest a strongly seasonal and relatively dry climate with a flashy discharge regime. Deposition of the Balta Fm in an area previously characterized by distal shelf and prodelta environments indicates large-scale progradation triggered by high sediment volume from the uplifting Carpathian Orogen and enhanced by a general lowering of Paratethys sea-level. The tripartite internal architecture of the Balta Fm indicates that progradation continued during deposition. Its wedge-shaped geometry suggests that tectonic activity in the Carpathians generated a 300 km wide foreland basin that

  9. Temporal and Petrogenetic Constraints on Volcanic Accretionary Processes at 9-10 Degrees North East Pacific Rise

    Science.gov (United States)

    2010-06-01

    crust (e.g., Allegre & Turcotte , 1986; Ben Othman & Allegre, 1990; Hirschmann & Stolper, 1996; Lundstrom et al., 1999; Prinzhofer et al., 1989). In...East Pacific Rise, 10ºN. Journal of Petrology 30 (5), 1245-1298. Allègre, C.J. & Turcotte , D.L. (1986). Implications of a two-component marble-cake

  10. Petrology of Amoeboid Olivine Aggregates in Antarctic CR Chondrites: Comparison With Other Carbonaceous Chondrites

    Science.gov (United States)

    Komatsu, M.; Fagan, T. J.; Yamaguchi, A.; Mikouchi, T.; Zolensky, M. E.; Yasutake, M.

    2016-01-01

    Amoeboid olivine aggregates (AOAs) are important refractory components of carbonaceous chondrites and have been interpreted to represent solar nebular condensates that experienced high-temperature annealing, but largely escaped melting. In addition, because AOAs in primitive chondrites are composed of fine-grained minerals (forsterite, anorthite, spinel) that are easily modified during post crystallization alteration, the mineralogy of AOAs can be used as a sensitive indicator of metamorphic or alteration processes. AOAs in CR chondrites are particularly important because they show little evidence for secondary alteration. In addition, some CR AOAs contain Mn-enriched forsterite (aka low-iron, Mn-enriched or LIME olivine), which is an indicator of nebular formation conditions. Here we report preliminary results of the mineralogy and petrology of AOAs in Antarctic CR chondrites, and compare them to those in other carbonaceous chondrites.

  11. Towards OWL-based Knowledge Representation in Petrology

    CERN Document Server

    Shkotin, Alex; Kudryavtsev, Dmitry

    2011-01-01

    This paper presents our work on development of OWL-driven systems for formal representation and reasoning about terminological knowledge and facts in petrology. The long-term aim of our project is to provide solid foundations for a large-scale integration of various kinds of knowledge, including basic terms, rock classification algorithms, findings and reports. We describe three steps we have taken towards that goal here. First, we develop a semi-automated procedure for transforming a database of igneous rock samples to texts in a controlled natural language (CNL), and then a collection of OWL ontologies. Second, we create an OWL ontology of important petrology terms currently described in natural language thesauri. We describe a prototype of a tool for collecting definitions from domain experts. Third, we present an approach to formalization of current industrial standards for classification of rock samples, which requires linear equations in OWL 2. In conclusion, we discuss a range of opportunities arising ...

  12. Formats

    Directory of Open Access Journals (Sweden)

    Gehmann, Ulrich

    2012-03-01

    Full Text Available In the following, a new conceptual framework for investigating nowadays’ “technical” phenomena shall be introduced, that of formats. The thesis is that processes of formatting account for our recent conditions of life, and will do so in the very next future. It are processes whose foundations have been laid in modernity and which will further unfold for the time being. These processes are embedded in the format of the value chain, a circumstance making them resilient to change. In addition, they are resilient in themselves since forming interconnected systems of reciprocal causal circuits.Which leads to an overall situation that our entire “Lebenswelt” became formatted to an extent we don’t fully realize, even influencing our very percep-tion of it.

  13. Petrological evidence for secular cooling in mantle plumes.

    Science.gov (United States)

    Herzberg, Claude; Gazel, Esteban

    2009-04-02

    Geological mapping and geochronological studies have shown much lower eruption rates for ocean island basalts (OIBs) in comparison with those of lavas from large igneous provinces (LIPs) such as oceanic plateaux and continental flood provinces. However, a quantitative petrological comparison has never been made between mantle source temperature and the extent of melting for OIB and LIP sources. Here we show that the MgO and FeO contents of Galapagos-related lavas and their primary magmas have decreased since the Cretaceous period. From petrological modelling, we infer that these changes reflect a cooling of the Galapagos mantle plume from a potential temperature of 1,560-1,620 degrees C in the Cretaceous to 1,500 degrees C at present. Iceland also exhibits secular cooling, in agreement with previous studies. Our work provides quantitative petrological evidence that, in general, mantle plumes for LIPs with Palaeocene-Permian ages were hotter and melted more extensively than plumes of more modern ocean islands. We interpret this to reflect episodic flow from lower-mantle domains that are lithologically and geochemically heterogeneous.

  14. The formation of the integration priorities of the Middle East Arab countries in the conditions of the global world order transformation

    OpenAIRE

    Tetyana Oriekhova; Al Makarikh Farid

    2010-01-01

    The article is devoted to the research of activation process of the international integration cooperation of the Middle East Arab countries in the conditions of ongoing transformations, which are obviously taking place in the global world order. The article gives the author’s definition of “integration maturity”, its characteristic features; concluded the integration maturity level of the Middle East Arab countries; identified the place of the Arab countries as players of the global economic ...

  15. Virtual petrological microscopy: web 2.0 technology for learning microscopy skills outside the laboratory

    Science.gov (United States)

    Kelley, S. P.; Whalley, P.; Tindle, A.

    2009-12-01

    Learning to use microscopes for geoscience or life science applications is a crucial part of the practical training offered in many science degrees, but the opportunities to study are often constrained by available laboratory space and time, and sometimes constrained by the number of high quality microscopes available. We will demonstrate a new based virtual petrological microscope which offers the opportunity for enhancement and enrichment of laboratory experience in geoscience. The focus of petrological microscope study is not primarily related to learning facts but is concerned with learning how to discriminate and classify within the paradigms of the discipline. In this case, the recognition and measurement of key features in rock samples in hand specimen and thin section. Whilst undertaking the practical exercise of recognition and naming of rock samples students are really being required to develop an understanding of the rock cycle as a model representing the relationship between rock categories and the process of their formation. The problems of teaching with complex visual materials, in effect of teaching learners 'how to see' from the scientific perspective of a particular discipline, are quite general. It could reasonably be expected that lessons learnt from the implementation and detailed evaluation of the proposed web-based system will generalise to many other topics in science education. Thus we focussed on the thin section images rather than reproducing a system that resembled a physical microscope. The virtual petrological microscope developed for a course at the Open University UK enables student acquisition of skills such as mineral and rock recognition using a browser window to explore thin sections of rocks as if they were using a laboratory microscope. The microscope allows students to pan around the thin sections (held as 1GB files on a remote server); zoom in and out, change from plane polarised light to cross polarised light conditions, and

  16. Lu-Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: evidence for the early Archean formation of continental crust

    Science.gov (United States)

    Choi, S.; Mukasa, S. B.; Andronikov, A. V.; Osanai, Y.; Harley, S. L.; Kelly, N. M.

    2009-12-01

    The Napier Complex in East Antarctica comprises some of the oldest rocks on earth (~3.8 billion years old), overprinted by an ultra-high temperature (UHT) metamorphic event near the Archean-Proterozoic boundary. Garnet, orthopyroxene, sapphirine, osumilite, rutile and a whole rock representing an equilibrated assemblage from this belt yield a Lu-Hf isochron age of 2,403 ± 43 Ma. Preservation of the UHT mineral assemblage in the rock analyzed suggests rapid cooling with closure likely to have occurred for the Lu-Hf system at post-peak UHT conditions near a temperature of ~800C. Individual zircon grains from Gage Ridge within the Napier Complex yielded a remarkably uniform range of 176Hf/177Hf values between 0.280433 ± 7 and 0.280505 ± 10, corresponding to ɛHf > +5.6 at 3.85 Ga relative to the chondritic uniform reservoir (CHUR). Because of their exceedingly low Lu/Hf values (<0.001), the grains are effectively recording the initial Hf isotope composition of the magmatic systems from which the gneiss protoliths crystallized. These results indicate that (1) the source of the crustal materials that formed the Napier Complex at 3.85 Ga were depleted relative to the CHUR. The extent of depletion involved is higher than has been predicted by extrapolation from the Lu-Hf isotopic evolution inferred for the source of Proterozoic and Phanerozoic basalts, judging from an fLu/Hf value of 0.51, (2) the depleted mantle reservoir has been in existence since very early in Earth’s history, in agreement with the early differentiation of the Earth that the latest core formation models require, and (3) an extremely depleted source also mean that the bulk of continental crust was extracted from the mantle by ~3.8 Ga. Moreover, the results demonstrate that even the oldest silicic rocks in the complex are not likely to have formed from remobilized older crustal materials, but were instead juvenile products of mantle melting. In addition, zircons with metamorphic rims have a similar

  17. 3D seismic structure of the Zhenbei-Huangyan seamount chain in the East sub-basin of the South China Sea and its mechanism of formation

    Science.gov (United States)

    Zhao, M.; Wang, J.; Qiu, X.; Sibuet, J. C.; He, E.; Zhang, J.

    2015-12-01

    The post-spreading volcanic ridge (PSVR) is oriented approximately E-W in its western part called the Zhenbei-Huangyan seamount chain. Where is the extinct spreading ridge (ESR) of the East Sub-basin located? beneath the PSVR (Li et al., 2014)? Or intersecting with the PSVR by N055° orientation (Sibuet et al., submitted)? A three-dimensional Ocean Bottom Seismometer (OBS) survey covered both the central extinct spreading ridge and the Zhenbei-Huangyan seamount chain, the IODP Site U1431 (Li et al., 2014) being located just north of the chain. The results of this experiment will provide the essential information to understand the emplacement of the PSVR within the previously formed oceanic crust. The comprehensive seismic record sections of 39 OBSs are of high quality and show clear and reliable P-wave seismic phases, such as Pg, Pn and PmP. These seismic arrivals provide strong constrains for modeling the detailed three-dimensional velocity structure. We will show that the crust is oceanic on each side of the Zhenbei-Huangyan seamount chain, where is the location of the ESR and what is the genetic relationship between the magma chambers and the overlying Zhenbei-Huangyan seamount chain. We suggest that the large thickness of the upper crust is possibly due to volcanic extrusions and the thickened lower crust to magmatic underplating. Combining previous geochemical study of PSVR outcropping samples, the formation mechanism of the seamount chain might be explained by a buoyancy decompression melting mechanism (Castillo et al., 2010). This research was granted by the Natural Science Foundation of China (91028002, 91428204, 41176053). ReferencesSibuet J.-C., Yeh Y.-C. and Lee C.-S., 2015 submitted. Geodynamics of the South China Sea: A review with emphasis on solved and unsolved questions. Tectonophysics. Li, C. F., et al. 2014. Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349. Geochemistry

  18. Granites petrology, structure, geological setting, and metallogeny

    CERN Document Server

    Nédélec, Anne; Bowden, Peter

    2015-01-01

    Granites are emblematic rocks developed from a magma that crystallized in the Earth’s crust. They ultimately outcrop at the surface worldwide. This book, translated and updated from the original French edition Pétrologie des Granites (2011) is a modern presentation of granitic rocks from magma genesis to their crystallization at a higher level into the crust. Segregation from the source, magma ascent and shapes of granitic intrusions are also discussed, as well as the eventual formation of hybrid rocks by mingling/mixing processes and the thermomechanical aspects in country rocks around granite plutons. Modern techniques for structural studies of granites are detailed extensively. Granites are considered in their geological spatial and temporal frame, in relation with plate tectonics and Earth history from the Archaean eon. A chapter on granite metallogeny explains how elements of economic interest are concentrated during magma crystallization, and examples of Sn, Cu, F and U ore deposits are presented. Mi...

  19. Petrology of Two Itokawa Particles: Comparison with Equilibrated LL Chondrites

    Science.gov (United States)

    Komatsu, M.; Mikouchi, T.; Arai, T.; Fagan, T. J.; Zolensky, M.; Hagiya, K.; Ohsumi, K.; Karouji, Y.

    2015-01-01

    A strong link between Itokawa particles and LL chondrites was confirmed by preliminary examinations of Hayabusa particles [e.g., 1, 2]. Both poorly equilibrated and highly equilibrated particles have been found among the grains returned from Itokawa [1], and it is suggested that they correspond to LL4 and LL5-6, respectively. Here we report the petrography of two Itokawa particles and TEM study of one, and compare them to Antarctic LL chondrites with variable petrologic types (LL4-LL7) in order to understand the metamorphic history of asteroid Itokawa.

  20. Petrology and classification of the Garraf, Spain chondrite

    Science.gov (United States)

    Keil, K.; Conrad, G. H.; King, E. A.; San Miguel, A.

    1986-01-01

    Microscopic and electron microprobe studies indicate that the Garraf meteorite is a highly-recrystallized chondrite of petrologic type 6. Olivine (Fa24.7; PMD 1.1) and low-Ca pyroxene (Fs20.9; PMD 1.1) compositions indicate that it belongs to the L-group. Based on contents of noble gases, pervasive fracturing of silicates, common undulose extinction of olivine and plagioclase, and the lack of melt pockets and maskelynite, Garraf is placed into shock facies b. It is concluded that Garraf is a highly recrystallized L6b chondrite that, after recrystallization, was cataclased and comminuted by shock.

  1. Igneous and metamorphic petrology in the field: a problem-based, writing-intensive alternative to traditional classroom petrology

    Science.gov (United States)

    DeBari, S. M.

    2011-12-01

    The Geology Department at Western Washington University (~100 geology majors) offers field and classroom versions of its undergraduate petrology course. This is a one-quarter course (igneous and metamorphic petrology) with mineralogy as a prerequisite. The field version of the course is offered during the three weeks prior to fall quarter and the classroom version is offered in spring quarter. We take 15-20 students around the state of Washington, camping at different outcrop sites where students integrate observational skills, petrologic knowledge, and writing. Petrogenetic associations in various tectonic settings provide the theme of the course. We compare ophiolites vs. arc sequences (volcanic, plutonic, and metamorphic rocks), S- vs. I-type granitoids (plutonic rocks and associated metamorphic rocks), Barrovian vs. Buchan vs. subduction zone metamorphism of different protoliths, and flood-basalt vs. active-arc volcanism. Some basics are covered in the first day at WWU, followed by 17 days of field instruction. Lecture is integrated with outcrop study in the field. For example, students will listen to a lecture about magma differentiation processes as they examine cumulate rocks in the Mt. Stuart batholith, and a lecture about metamorphic facies as they study blueschist facies rocks in the San Juan Islands. Students study multiple outcrops around a site for 1-4 days. They then use their observations (sketches and written descriptions of mineral assemblages, rock types, rock textures, etc.) and analysis techniques (e.g. geochemical data plotting, metamorphic protolith analysis) to write papers in which the data are interpreted in terms of a larger tectonic problem. In advance of the writing process, students use group discussion techniques such as whiteboarding to share their observational evidence and explore interpretations. Student evaluations indicate that despite the intense pace of the course, they enjoy it more. Students also feel that they retain more

  2. Petrology and chemistry of Apollo 17 regolith breccias - A history of mixing of highland and mare regolith

    Science.gov (United States)

    Simon, S. B.; Papike, J. J.; Gosselin, D. C.; Laul, J. C.; Hughes, S. S.

    1990-01-01

    Results are presented of petrological and chemical analyses of ten Apollo 17 breccias, showing that two of these consist predominantly of highland material, seven are mare-dominated, and one is a welded volcanic glass deposit; all were formed at or near the Apollo 17 site, and all contain both mare and highland components. The data are indicative of the Apollo 17 breccias formation from immature source regolith. The breccias are considered to be formed locally after an eruption of basalt and orange glass at the site. Since the formation of the breccias, the regolith at the Apollo 17 site has become more mature, and the orange glass abundance has been somewhat decreased by mixing. One of the sample may contain a previously unreported volcanic glass type.

  3. Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N:Evidence from mineralogical and geochemical data

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103°54.48’W, lat. 12°42.30’N, water depth 2655 m) on the East Pacific Rise near lat 13°N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%―1.85%) and Co (65×10?6―704×10?6) contents, and contain Co+Cu+Zn+Ni> 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13°N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13°N are lower in ΣREE (5.44×10?6―17.01×10?6), with a distinct negative Ce anomaly (0.12 ― 0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13°N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples

  4. MoonDB: Restoration and Synthesis of Lunar Petrological and Geochemical Data

    Science.gov (United States)

    Lehnert, Kerstin A.; Cai, Yue; Mana, Sara; Todd, Nancy S.; Zeigler, Ryan A.; Evans, Cindy A.

    2016-01-01

    About 2,200 samples were collected from the Moon during the Apollo missions, forming a unique and irreplaceable legacy of the Apollo program. These samples, obtained at tremendous cost and great risk, are the only samples that have ever been returned by astronauts from the surface of another planetary body. These lunar samples have been curated at NASA Johnson Space Center and made available to the global research community. Over more than 45 years, a vast body of petrological, geochemical, and geochronological studies of these samples have been amassed, which helped to expand our understanding of the history and evolution of the Moon, the Earth itself, and the history of our entire solar system. Unfortunately, data from these studies are dispersed in the literature, often only available in analog format in older publications, and/or lacking sample metadata and analytical metadata (e.g., information about analytical procedure and data quality), which greatly limits their usage for new scientific endeavors. Even worse is that much lunar data have never been published, simply because no forum existed at the time (e.g., electronic supplements). Thousands of valuable analyses remain inaccessible, often preserved only in personal records, and are in danger of being lost forever, when investigators retire or pass away. Making these data and metadata publicly accessible in a digital format would dramatically help guide current and future research and eliminate duplicated analyses of precious lunar samples.

  5. Linking petrology and seismology at an active volcano.

    Science.gov (United States)

    Saunders, Kate; Blundy, Jon; Dohmen, Ralf; Cashman, Kathy

    2012-05-25

    Many active volcanoes exhibit changes in seismicity, ground deformation, and gas emissions, which in some instances arise from magma movement in the crust before eruption. An enduring challenge in volcano monitoring is interpreting signs of unrest in terms of the causal subterranean magmatic processes. We examined over 300 zoned orthopyroxene crystals from the 1980-1986 eruption of Mount St. Helens that record pulsatory intrusions of new magma and volatiles into an existing larger reservoir before the eruption occurred. Diffusion chronometry applied to orthopyroxene crystal rims shows that episodes of magma intrusion correlate temporally with recorded seismicity, providing evidence that some seismic events are related to magma intrusion. These time scales are commensurate with monitoring signals at restless volcanoes, thus improving our ability to forecast volcanic eruptions by using petrology.

  6. Petrology, chemistry, age and irradiation history of Luna 24 samples

    Science.gov (United States)

    Wasserburg, G. J.; Papanastassiou, D. A.; Mcculloch, M. T.; Huneke, J. C.; Dymek, R. F.; Depaolo, D. J.; Chodos, A. A.; Albee, A. L.; Radicati Di Brozolo, F.

    1978-01-01

    The results of petrological, chemical, isotopic age determination and irradiation studies of sample 24170 from the 170 cm depth of the regolith core returned from Mare Crisium by Luna 24 are presented. The sample is found to be comprised of fragments from a single igneous rock, with mineralogical evidence indicating it to be a mare basalt. The crystallization age is determined by Sm-Nd and Ar(40)-Ar(39) ages to be 3.30 AE, establishing the presence of relatively young flows. All soil samples show low trace element compositions with minimum contamination by KREEPUTh-rich materials. Rb-Sr and Sm-Nd relations reflect the absence of significant fractionation at ages younger than 4.5 AE. One soil sample shows extremely large neutron capture effects, imposing a new lower limit to the neutron production rate in the regolith and requiring the addition of irradiated materials from depth.

  7. Petrologic and In Situ Geochemical Constraints on Diogenite Genesis

    Science.gov (United States)

    Mittlefehldt, David W.; Peng, Z. X.

    2013-01-01

    Diogenites, members of the howardite, eucrite and diogenite (HED) clan, are orthopyroxenite, harzburgite and dunite meteorites [1-3]. Most are breccias, but remnant textures indicate they were originally coarse-grained rocks, with grain sizes of order of cm. Their petrography and compositions support an origin as crustal cumulates from a differentiated asteroid. Astronomical observations, and surface mineralogy and composition of Vesta determined by the Dawn spacecraft suggest that asteroid (4) Vesta is the parent object for HED meteorites [4-6]. The origin of diogenites is an unsettled issue. It is difficult to fit their bulk compositional characteristics into global magma ocean models that successfully describe the compositions of basaltic and cumulate eucrites [7]. Compositional analyses of acid-leached bulk samples have led to the hypothesis that many diogenites were formed late by interaction of their parent melts with a eucritic crust [8]. Those observations may alternatively be explained by subsolidus equilibration of trace elements between orthopyroxene and minor/ accessory phases in the rocks such as plagioclase and phosphate [7]. These competing hypotheses can be tested through in situ measurements of trace and minor elements in orthopyroxene. Our new petrologic observations and in situ minor and trace element data for a suite of diogenites are used to discuss the petrologic evolution of diogenites. Our preliminary data on two diogenites are consistent with the hypothesis that subsolidus element mobilization processes caused unusual trace element signatures seen in some diogenites [7]. We cannot stress strongly enough, however, that the sample set is too small and that additional data are required before definitive conclusions can be made.

  8. The Formation of Barrier Winds East of the Loess Plateau and Their Effects on Dispersion Conditions in the North China Plains

    Science.gov (United States)

    Hu, Xiao-Ming; Li, Xingliang; Xue, Ming; Wu, Dui; Fuentes, Jose D.

    2016-10-01

    The North China Plain (NCP) to the east of the Loess Plateau is one of the most heavily polluted areas in the world. Weak surface flow in the western part of the NCP exacerbates the air pollution in this region. Deceleration of low-level flow when approaching the Loess Plateau, together with enhanced roughness associated with large cities, were previously ascribed as the causes for low wind speeds in the NCP. Using numerical simulations with a one-layer dispersion model, we identify that dynamic modification of airflow by the Loess Plateau (not just simple deceleration due to mountain blocking) plays an important role in reducing the wind speed over the NCP. Dynamically-induced northerly barrier winds, superimposed on the prevailing southerly/south-easterly flow, reduce the wind speed in a 50-100 km wide region to the east of the Plateau, partially explaining the weak winds in the western part of the NCP. Poor dispersion conditions due to weak horizontal winds likely contribute to the accumulation of pollutants in this region.

  9. Petrological and seismic precursors of the paroxysmal phase of the last Vesuvius eruption on March 1944

    National Research Council Canada - National Science Library

    Pappalardo, Lucia; D'Auria, Luca; Cavallo, Andrea; Fiore, Stefano

    2014-01-01

    .... In our research, the combined investigation of both petrological and seismic indicators has been applied for the first time to a Vesuvius eruption, that of March 1944 that caused the present dormant...

  10. The effect of an East Pacific Rise offset on the formation of secondary cracks ahead of the Cocos-Nazca Rift at the Galapagos Triple Junction

    Science.gov (United States)

    Smith, D. K.; Montesi, L. G.; Schouten, H.; Zhu, W.

    2011-12-01

    A succession of short-lived, E-W trending cracks at the Galapagos Triple Junction north and south of the Cocos-Nazca (C-N) Rift, has been explained by a simple crack interaction model. The locations of where the cracks initiate are controlled by tensile stresses generated at the East Pacific Rise (EPR) by two interacting cracks: One representing the north-south trending EPR, and the other the large, westward propagating C-N Rift, whose tip is separated from the EPR by a distance D. The model predicts symmetric cracking at the EPR north and south of the C-N Rift tip. Symmetry in the distribution of cracks north and south of the C-N Rift is observed and especially remarkable between 2.5 and 1.5 Ma when the rapid jumping of cracks toward the C-N Rift appears synchronous. The rapid jumping can be explained by decreasing D, which means that the tip of the C-N Rift was moving closer to the EPR. Symmetry of cracking breaks down at 1.5 Ma, however, with the establishment of the Dietz Deep Rift, the southern boundary of the Galapagos microplate. Symmetry of cracking also breaks down on older crust to the east between about 100 35'W and 100 45'W (about 2.6 Ma) where a rapid jumping of cracks toward the C-N Rift is observed in the south cracking region. There is no evidence of similar rapid jumping in the north cracking region. It could be simply that the response to changing the value of D is not always as predicted. It could also be that the shape of the EPR has not always been symmetric about the C-N Rift, as assumed in the model. Currently, an overlapping spreading center with a 15 km east-west offset between the limbs of the EPR has formed at 1 50'N. We assess the importance of the geometry of the EPR on the crack interaction model. The model has been modified to include a ridge offset similar to what is observed today. We find that the region of stress enhancement at the EPR (where cracks initiate) is subdued south of the C-N Rift tip because of the EPR offset. It is

  11. Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

    Science.gov (United States)

    Aulbach, Sonja; Massuyeau, Malcolm; Gaillard, Fabrice

    2017-01-01

    Geophysically detectible mid-lithospheric discontinuities (MLD) and lithosphere-asthenosphere boundaries (LAB) beneath cratons have received much attention over recent years, but a consensus on their origin has not yet emerged. Cratonic lithosphere composition and origin is peculiar due to its ultra-depletion during plume or accretionary tectonics, cool present-day geothermal gradients, compositional and rheological stratification and multiple metasomatic overprints. Bearing this in mind, we integrate current knowledge on the physical properties, chemical composition, mineralogy and fabric of cratonic mantle with experimental and thermodynamic constraints on the formation and migration of melts, both below and within cratonic lithosphere, in order to find petrologically viable explanations for cratonic mantle discontinuities. LABs characterised by strong seismic velocity gradients and increased conductivity require the presence of melts, which can form beneath intact cratonic roots reaching to 200-250 km depth only in exceptionally warm and/or volatile-rich mantle, thus explaining the paucity of seismical LAB observations beneath cratons. When present, pervasive interaction of these - typically carbonated - melts with the deep lithosphere leads to densification and thermochemical erosion, which generates topography at the LAB and results in intermittent seismic LAB signals or conflicting seismic, petrologic and thermal LAB depths. In rare cases (e.g. Tanzanian craton), the tops of live melt percolation fronts may appear as MLDs and, after complete lithosphere rejuvenation, may be sites of future, shallower LABs (e.g. North China craton). Since intact cratons are presently tectonomagmatically quiescent, and since MLDs produce both positive and negative velocity gradients, in some cases with anisotropy, most MLDs may be best explained by accumulations (metasomes) of seismically slow minerals (pyroxenes, phlogopite, amphibole, carbonates) deposited during past

  12. SNC meteorites - Clues to Martian petrologic evolution?. [Shergottites, Nakhlites and Chassigny

    Science.gov (United States)

    Mcsween, H. Y., Jr.

    1985-01-01

    Shergottites, nakhlites and the Chassigny meteorites (SNC group) may have originated on Mars. The shergottites are medium-grained basalts, the nakhlites are pyroxenites and the Chassigny is a dunite. The SNC group is petrologically diverse but differs from all other known achondrites in terms of mineral chemistry, the redox state, the oxygen isotopic composition and the radiometric ages. The SNC stones are mafic and ultramafic cumulate rocks with mineralogies that indicate rapid cooling and crystallization from tholeiitic magmas which contained water and experienced a high degree of oxidation. The characteristics suggest formation from a large parent body, i.e., a planet, but not earth. The estimated ages for the rocks match the estimated ages for several mapped Martian volcanoes in the Tharsis region. Additionally, the elemental and isotopic abundances of atmospheric gases embedded in melts in the SNC stones match Viking Lander data for the Martian atmosphere. However, reasons are cited for discounting the possibility that a large meteorite(s) collided with Mars about 180 myr ago and served as the mechanism for ejecting the SNC stones to earth.

  13. Petrology,Chronology and Isotope Geochemistry of the Proterozoic Amphibolites from Xiangshan,Central Jiangxi Province,China

    Institute of Scientific and Technical Information of China (English)

    胡恭任; 章邦桐; 等

    1999-01-01

    On the basis of a comprehensive study on the petrology,trace elements and isotopic geochemistry of the Xiangshan amphibolites,we suggest that the protoliths of the amphibolites were basalts formed in an island-arc tectonic setting.The basaltic magma was derived from a slightly depleted mantle source with a small amount of crustal contamination.Assemblage of the rock-froming minerals indicates that these amphibolites underwent a low-grade metamorphism of amphibolite facies.According to the formation age(1113Ma) and subsequent metamophic age(726.6Ma) of the basalts aw well as the geological and gochemical features of these amphibolites,a tectonic model of Proterozoic oceanic island-arc setting is proposed for central Jiangxi.

  14. Petroleum systems and geologic assessment of undiscovered oil and gas, Cotton Valley group and Travis Peak-Hosston formations, East Texas basin and Louisiana-Mississippi salt basins provinces of the northern Gulf Coast region. Chapters 1-7.

    Science.gov (United States)

    ,

    2006-01-01

    The purpose of the U.S. Geological Survey's (USGS) National Oil and Gas Assessment is to develop geologically based hypotheses regarding the potential for additions to oil and gas reserves in priority areas of the United States. The USGS recently completed an assessment of undiscovered oil and gas potential of the Cotton Valley Group and Travis Peak and Hosston Formations in the East Texas Basin and Louisiana-Mississippi Salt Basins Provinces in the Gulf Coast Region (USGS Provinces 5048 and 5049). The Cotton Valley Group and Travis Peak and Hosston Formations are important because of their potential for natural gas resources. This assessment is based on geologic principles and uses the total petroleum system concept. The geologic elements of a total petroleum system include hydrocarbon source rocks (source rock maturation, hydrocarbon generation and migration), reservoir rocks (sequence stratigraphy and petrophysical properties), and hydrocarbon traps (trap formation and timing). The USGS used this geologic framework to define one total petroleum system and eight assessment units. Seven assessment units were quantitatively assessed for undiscovered oil and gas resources.

  15. The borehole instability mechanism and countermeasure to Permian Liangshan formation in east of Sichuan%川东地区二迭系梁山组地层井壁不稳定机理及对策

    Institute of Scientific and Technical Information of China (English)

    梁大川; 崔茂荣; 黄进军

    2001-01-01

    川东地区属高陡构造,二迭系梁山组地层破碎松散,断层多,钻井过程中常遇掉块、坍塌、泥页岩水化膨胀缩径等严重井下复杂情况,已成为该地区深井钻探的严重障碍。在分析地层岩石矿物组成微观结构和理化特性的基础上,从地质、水化、物理和工程等方面分析井壁失稳机理,提出梁山组地层防塌技术对策:①严格控制当量钻井液密度;②钻井液应具有良好的封堵性和抑制性;③严格控制失水小于10ml;④钻井液pH值控制在8~9;⑤尽量缩短浸泡时间。%East of Sichuan area is belong to high and steep structure. For Permian Liangshan formation is broken formarion and has many fault, wall sloughing, shale hydrate expansion and hole diameter reduction etc. downhole complex accident are often encountered during drilling. These cases have become serious obstruct to drill deep well in east of Sichuan. On the basis of analysis of structure and physicochemical characteristic of formation rock mineral, this paper analyzes the sidewall instability mechanism in geology, shale hydration, physics and engineering aspects. The technique countermeasures for hole sloughing prevention are proposed, including suitable mud density, good seal and inhibition for drilling fluid, water loss less than 1Oml and shorten soak time etc..

  16. From static to dynamic provenance analysis-Sedimentary petrology upgraded

    Science.gov (United States)

    Garzanti, Eduardo

    2016-05-01

    The classical approach to sandstone petrology, established in the golden years of plate tectonics and based on the axiom that "detrital modes of sandstone suites primarily reflect the different tectonic settings of provenance terranes," has represented a benchmark for decades. The composition of sand and sandstone, however, simply provides us with a distorted image of the lithological structure of source terranes and gives us little clue whether they are allochthonous or autochthonous, orogenic or anorogenic, young or old. What we may able to see reflected in detrital modes is the nature of source terranes (continental, arc, oceanic) and the tectonostratigraphic level reached by erosion in space and time. The proposed new approach to the petrology of sand and sandstone (1) starts with a simple classification scheme circulated since the 1960s, which is purely descriptive, objective, and free of ill-defined ambiguous terms and (2) focuses on the nature and tectonostratigraphic level of source terranes. Further steps are essential to upgrade provenance analysis. Acquiring knowledge from modern settings is needed to properly identify and wherever possible correct for physical and chemical processes introducing environmental and diagenetic bias and thus address nature's complexities with adequate conceptual tools. Equally important is the integration of multiple techniques, ideally including bulk-sediment, multi-mineral, and single-mineral methods. Bulk-sediment petrography remains the fundamental approach that allows us to capture the most precious source of direct provenance information, represented by the mineralogy and texture of rock fragments. Bulk-sediment geochemistry, applicable also to silt and clay carried in suspension, is a superior method to check for hydraulic sorting, chemical weathering, and fertility of detrital minerals in different sediment sources. Detrital geochronology, thermochronology, and isotope geochemistry reveal the diverse time structures

  17. Petrologic Locations of Nanodiamonds in Carbonaceous Chondrite Meteorites

    Science.gov (United States)

    Garvie, Laurence

    Nanodiamonds (NDs), with dimensions near two nanometers, are widespread accessory minerals in primitive meteorites. They have been studied extensively in concentrates made from acid-insoluble residues, but surprisingly little is known about their petrologic settings in the meteorites because they have not been studied in situ. Information about such settings is fundamental for determining how they formed and were incorporated into the meteorites. The primary goal of the planned research is to determine and compare the petrologic settings of NDs within matrix of different types of carbonaceous chondrites, with the long-term aim of providing new insights regarding the origin of NDs. This research will also provide new data on the structure and major and trace element compositions of individual NDs and regions within them. Transmission electron microscopes (TEMs) provide uniquely powerful information regarding chemical, bonding, and structural data on the scale needed to solve this problem, assuming the NDs can be located within the host matrix. We have developed methods of observing NDs in situ within the fine-grained matrix of primitive meteorites and will use various TEMs to accomplish that goal for several meteorites. High- resolution imaging and electron energy-loss spectroscopy (EELS) will permit determination of both structural and chemical information about the NDs and their adjacent minerals. By the middle of the proposed grant period, two state-of-the-art, aberration-corrected TEMs will have been installed at ASU and will be used to locate heavy elements such as Xe, Te, and Pd within the NDs. These TEMs permit the imaging of individual atoms of heavy elements with annular dark-field (ADF) imaging, and these atoms can be identified using EELS. The result of these new types of measurements will provide information about whether such elements, which have been used to determine whether NDs formed in supernovae, occur within the interiors or on the surfaces of

  18. Insights into the dolomitization process and porosity modification in sucrosic dolostones, Avon Park Formation (Middle Eocene), East-Central Florida, U.S.A.

    KAUST Repository

    Maliva,, Robert G.

    2011-03-01

    The Avon Park Formation (middle Eocene) in central Florida, U.S.A., contains shallow-water carbonates that have been replaced by dolomite to varying degrees, ranging from partially replaced limestones, to highly porous sucrosic dolostones, to, less commonly, low-porosity dense dolostones. The relationships between dolomitization and porosity and permeability were studied focusing on three 305-m-long cores taken in the City of Daytona Beach. Stable-isotope data from pure dolostones (mean δ 18O = +3.91% V-PDB) indicate dolomite precipitation in Eocene penesaline pore waters, which would be expected to have been at or above saturation with respect to calcite. Nuclear magnetic log-derived porosity and permeability data indicate that dolomitization did not materially change total porosity values at the bed and formation scale, but did result in a general increase in pore size and an associated substantial increase in permeability compared to limestone precursors. Dolomitization differentially affects the porosity and permeability of carbonate strata on the scale of individual crystals, beds, and formations. At the crystal scale, dolomitization occurs in a volume-for-volume manner in which the space occupied by the former porous calcium carbonate is replaced by a solid dolomite crystal with an associated reduction in porosity. Dolomite crystal precipitation was principally responsible for calcite dissolution both at the actual site of dolomite crystal growth and in the adjoining rock mass. Carbonate is passively scavenged from the formation, which results in no significant porosity change at the formation scale. Moldic pores after allochems formed mainly in beds that experienced high degrees of dolomitization, which demonstrates the intimate association of the dolomitization process with carbonate dissolution. The model of force of crystallization-controlled replacement provides a plausible explanation for key observations concerning the dolomitization process in the

  19. The Evolution of Triassic Granites Associated with Mineralization within East Kunlun Orogenic Belt:Evidence from the Petrology,Geochemistry and Zircon U-Pb Geochronology of the Mohexiala Pluton%东昆仑与成矿有关的三叠纪花岗岩演化:基于莫河下拉岩体岩石学、地球化学和锆石 U-Pb 年代学的证据

    Institute of Scientific and Technical Information of China (English)

    张炜; 周汉文; 朱云海; 毛武林; 佟鑫; 马占青; 曹永亮

    2016-01-01

    The East Kunlun orogenic belt is not only an important intrusive magmatic tectonic belt,but also a very important poly-metallic metallogenic belt for national economy.There are a large number of granites associated with mineralization formed in Triassic in this area,but the connection between them and the relationship about the tectogenesis are still not clear.In this paper,detailed petrography,element geochemical and zircon geochronological studies are presented for the Mohexiala granite-porphyry associated with silver poly-metallic ore;we summarize the characteristics of Triassic granites associated with minerali-zation within the East Kunlun orogenic belt,and discuss their evolution.Results show that:(1)the Triassic granites associat-ed with mineralization within East Kunlun orogenic belt have a clear trend from low-K and mid-K calc-alkaline series to high-K calc-alkaline and shoshonite series during 250-200 Ma,their A/NK ratios decreased from 2.0 to 1.0 during 240-200 Ma;(2) the (87 Sr/86 Sr)i ratios between 0.710 to 0.715,εNd (t)=-0.6-0.0,the value ofεHf (t)are concentrated in -5-1 and the peak ranges between -2 to -1,indicating that the East Kunlun Triassic granites associated with mineralization were derived from the sources of ancient crust and mixed by mantle material;(3)the East Kunlun area got into the post-orogenic stage at 240 Ma and a large number of calc-alkaline granites formed,the granites gradually reduced after 220 Ma and some alkaline A-type granites occurred between 204 Ma and 210 Ma which indicates that the orogenic belt transformed from collision-orogeny to the intraplate break-up stage.%东昆仑造山带在三叠纪不仅是一个重要的构造-岩浆带,也是一个对于国民经济非常重要的多金属成矿带.该区在三叠纪形成了大量与成矿有关的花岗岩,它们之间的联系、与区域构造运动的关系目前尚未明确.在莫河下拉银多金属矿花岗斑岩岩相学、地球化学和锆石年

  20. Tectonic evolution of the East Junggar terrane, CAOB

    Science.gov (United States)

    Xu, Xing-Wang

    2016-04-01

    The East Junggar terrane is one of the important tectonic units of the Central Asian Orogenic Belt (CAOB; Zonenshain et al., 1990). Debate surrounds the tectonics of the East Junggar area, including tectonic setting, age, basement nature, subduction polarity and collisional time between the East Junggar terrane and Junggar block (e.g., Xiao et al., 2008, 2011; Long et al., 2012; Huang et al., 2012). Among the two popular models, one suggests that the Junggar is a continental block (e.g. Zhang et al., 1984, 1993; Watson et al., 1987; Xiao et al., 1992; He et al., 1994; Li et al., 2000; Charvet et al., 2001, 2007; Xu et al., 2003; Zhao et al., 2003; Buslov et al., 2004; Xu and Ma, 2004; Dong et al., 2009; Bazhenov et al., 2012; Choulet et al., 2012; Zhang et al., 2012). The other model proposes that the Junggar has a basement of Paleozoic oceanic crust (e.g., Carroll et al., 1990; Zheng et al., 2007) or oceanic island arc complexes (e.g., Coleman, 1989; Chen and Jahn, 2004; Windley et al., 2007) of the Altaid Paleozoic rocks (e.g., Sengör et al., 1993; Sengör and Natal'in, 1996; Allen and Vincent, 1997; Filippova et al., 2001; Xiao et al., 2004a, 2004b, 2008, 2009, 2010a, 2010b, 2012). The tectonics in the Eastern Junggar area are interpreted to be related to late Paleozoic intra-oceanic accretion induced by northward subduction of the Junggar oceanic lithosphere (e.g. Xiao et al., 2008, 2009; Biske and Seltmann, 2010; Wan et al., 2011; Yang et al., 2011) or by the southward subduction of the Paleo-Asian oceanic lithosphere (Zhang et al., 2004; Wong et al., 2010; Su et al., 2012). Recently, we did detailed field survey and petrological, geochemical and chronological analysis of the metamorphosed volcanic rocks and magmatic rocks, and new discovered gneiss and magnetite quartzite enclaves from the Taheir tectonic window in the East Junggar region which is situated between the Zaisan-Erqis-the Main Mongolian Lineament-suture and the Kelameili suture. The new results

  1. Petrologic and REE Geochemical Characters of Burnt Rocks

    Institute of Scientific and Technical Information of China (English)

    HUANG Lei; LIU Chiyang; YANG Lei; ZHAO Junfeng; FANG Jianjun

    2008-01-01

    The study of burnt rocks is beneficial to the discussion on the tectonic movement,paleoclimate and paleogeography that coal seams are subjected to after they were formed. In order to obtain the basic data on the features of the burnt rocks, a systematic study of petrology and REE geochemistry on burnt rocks in Shenmu, Northern Shaanxi Province has been done, using the methods of SEM, EDS, susceptibility measurements and ICP-MS. The burnt rocks are divided into two series in the section: the melted rocks and the baked rocks. SEM and EDS analyses reveal that all the minerals show burnt and melted traces, and there are no clay minerals except iliite found in the burnt rocks. Susceptibility measurements reveal that the burnt rocks have abnormally high susceptibility values,whereas a geochemical analysis shows that the REE distribution pattern of burnt rocks is similar to that of sedimentary rocks (initial rocks). In the longitudinal section, with increasing degree of burning (from baked rocks to melted rocks), the ΣREE gradually decreases, and the total REE of melted rocks is obviously lower than that of baked rocks. Besides, the melted rocks show apparent negative Ce anomalies, while the baked rocks show no anomaly of Ce, and sometimes even show positive anomalies.

  2. Petrology of Igneous Rocks in Northern Golpayegan, Iran

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A preliminary study on petrological features of igneous rocks was carried out in northern Golpayegan, Iran, in an area of about 60 km2. According to the limited available data the sequence of the magma activity could be considered as follows: (1) Precambrian (?) granite connected with a continental-continental collision event, (2) Precambrian (?) syenite emplaced at a post continental-continental collision environment, (3) Cretaceous volcanic rocks generated by a local extensional system at an active continental margin and (4) Cenozoic doleritic veins generated in a post collision event. Geochemical characteristics of the granitic intrusion show that it originated from crust and belongs to S-type one. Syenitic body consists of syenitic affinities ranging from alkali-syenite to syenodiorite. These rocks were cut by Cenozoic doleritic veins, which consist of dolerite and olivine dolerite. Both syenite and dolerite are thought to originate from upper mantle but their ages are different. Cretaceous volcanic rocks include basalt, andesite, trachyandesite, trachyte and tuff. They are compositionally alkaline and erupted in a shallow graben basin. Their eruption has been in connection with deep-seated faults, which brought out the magma from the source.

  3. Simulated experiment evidences of the corrosion and reform actions of H2S to carbonate reservoirs: an example of Feixianguan Formation, east Sichuan

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The reservoir of Feixianguan Formation of the Lower Triassic in the Sichuan Basin is the deepest buried carbonate reservoir in China, with developed secondary corrosion holes, high quantities carbonate reservoir, maximum effective carbonate reservoir thickness. Also Feixianguan gas reservoir has the highest quantities of H2S. Research discovers that there are close relationships between the formation of reservoir and H2S. The mutual actions between acidity fluid and carbonate promoted the forming of secondary carbonate holes. Through the experiment of corrosion of the samples of Feixianguan carbonate reservoir in saturated aqueous solution of hydrogen sulfide, the porosity and permeability increased greatly, porosity increased 2% and permeability increased nearly two quantity degrees, also the density became light, which confirm the corrosion and reform actions of H2S to carbonate.

  4. Formation and metamorphism of stratified firn at sites located under spatial variations of accumulation rate and wind speed on the East Antarctic ice divide near Dome Fuji

    Directory of Open Access Journals (Sweden)

    S. Fujita

    2012-03-01

    Full Text Available The initial stage of postdepositional metamorphism in polar firn was investigated at sites located under spatial variations of accumulation rate and wind speed along the East Antarctic ice divide near Dome Fuji. A better understanding of this process is important for interpreting local insolation proxies used for astronomical dating of deep ice cores. Three 2–4 m deep pits were excavated and physical properties, including density ρ, grain size D, reflectance R of near infrared light and microwave dielectric anisotropy Δε, were investigated at high spatial resolution. We found that Δε ranges between 0.028 and 0.067 and that such high values occur in the surface ~0.1 m. In addition, short scale variations of ρ are correlated with those of Δε, and inversely correlated with those of D, confirming contrasting development of initially higher density layers and initially lower density layers. Moreover, postdepositional metamorphism makes these contrasts more distinct with increasing depths. Both the contrasts and Δε for given values of ρ are higher under lower accumulation rate conditions and under less windy conditions. Insolation efficiently causes evolution of strata of firn at the ice sheet surface under such conditions. Under more windy conditions, the strata contain more wind-driven hard layers with higher ρ and Δε and thus have larger fluctuations of ρ and Δε. We suggest that the initial variability of ρ at the surface and the duration of exposure to diurnal and seasonal temperature gradients play sequential roles in determining the physical/mechanical properties of firn, which is retained throughout the densification process.

  5. Multi-year application of WRF-CAM5 over East Asia-Part I: Comprehensive evaluation and formation regimes of O3 and PM2.5

    Energy Technology Data Exchange (ETDEWEB)

    He, Jian; Zhang, Yang; Wang, Kai; Chen, Ying; Leung, Lai-Yung; Fan, Jiwen; Li, Meng; Zheng, Bo; Zhang, Qiang; Duan, Fengkui; He, Kebin

    2017-06-09

    Accurate simulations of air quality and climate require robust model parameterizations on regional and global scales. The Weather Research and Forecasting model with Chemistry version 3.4.1 has been coupled with physics packages from the Community Atmosphere Model version 5 (CAM5) (WRF-CAM5) to assess the robustness of the CAM5 physics package for regional modeling at higher grid resolutions than typical grid resolutions used in global modeling. In this two-part study, Part I describes the application and evaluation of WRF-CAM5 over East Asia at a horizontal resolution of 36-km for six years: 2001, 2005, 2006, 2008, 2010, and 2011. The simulations are evaluated comprehensively with a variety of datasets from surface networks, satellites, and aircraft. The results show that meteorology is relatively well simulated by WRF-CAM5. However, cloud variables are largely or moderately underpredicted, indicating uncertainties in the model treatments of dynamics, thermodynamics, and microphysics of clouds/ices as well as aerosol-cloud interactions. For chemical predictions, the tropospheric column abundances of CO, NO2, and O3 are well simulated, but those of SO2 and HCHO are moderately overpredicted, and the column HCHO/NO2 indicator is underpredicted. Large biases exist in the surface concentrations of CO, NO2, and PM10 due to uncertainties in the emissions as well as vertical mixing. The underpredictions of NO lead to insufficient O3 titration, thus O3 overpredictions. The model can generally reproduce the observed O3 and PM indicators. These indicators suggest to control NOx emissions throughout the year, and VOCs emissions in summer in big cities and in winter over North China Plain, North/South Korea, and Japan to reduce surface O3, and to control SO2, NH3, and NOx throughout the year to reduce inorganic surface PM.

  6. Multi-year application of WRF-CAM5 over East Asia-Part I: Comprehensive evaluation and formation regimes of O3 and PM2.5

    Science.gov (United States)

    He, Jian; Zhang, Yang; Wang, Kai; Chen, Ying; Leung, L. Ruby; Fan, Jiwen; Li, Meng; Zheng, Bo; Zhang, Qiang; Duan, Fengkui; He, Kebin

    2017-09-01

    Accurate simulations of air quality and climate require robust model parameterizations on regional and global scales. The Weather Research and Forecasting model with Chemistry version 3.4.1 has been coupled with physics packages from the Community Atmosphere Model version 5 (CAM5) (WRF-CAM5) to assess the robustness of the CAM5 physics package for regional modeling at higher grid resolutions than typical grid resolutions used in global modeling. In this two-part study, Part I describes the application and evaluation of WRF-CAM5 over East Asia at a horizontal resolution of 36-km for six years: 2001, 2005, 2006, 2008, 2010, and 2011. The simulations are evaluated comprehensively with a variety of datasets from surface networks, satellites, and aircraft. The results show that meteorology is relatively well simulated by WRF-CAM5. However, cloud variables are largely or moderately underpredicted, indicating uncertainties in the model treatments of dynamics, thermodynamics, and microphysics of clouds/ices as well as aerosol-cloud interactions. For chemical predictions, the tropospheric column abundances of CO, NO2, and O3 are well simulated, but those of SO2 and HCHO are moderately overpredicted, and the column HCHO/NO2 indicator is underpredicted. Large biases exist in the surface concentrations of CO, NOx, and PM10 due to uncertainties in the emissions as well as vertical mixing. The underpredictions of NO lead to insufficient O3 titration, thus O3 overpredictions. The model can generally reproduce the observed O3 and PM indicators. These indicators suggest to control NOx emissions throughout the year, and VOCs emissions in summer in big cities and in winter over North China Plain, North/South Korea, and Japan to reduce surface O3, and to control SO2, NH3, and NOx throughout the year to reduce inorganic surface PM.

  7. Stratigraphic and Petrological Constraints of Cretaceous Subduction Initiation and Arc-Continent Collision in the Northern Andes

    Science.gov (United States)

    Leon, S.; Cardona, A.; Mejia, D.; Parra, M.

    2014-12-01

    Middle to Late-Cretaceous orogenic events in the northern Andes have been commonly reconstructed from the analysis of inland basins or the integration of regional scale thermochronological, geochronological and geochemical datasets from the accreted blocks. In contrast, limited studies have been developed on the stratigraphic and deformational record of magmatic and sedimentary sequences exposed near the suture zones. New field and petrologic data are used to characterize an ophiolite type sequence that outcrops in the western flank from the northwestern segment of the Central Cordillera of Colombia. Stratigraphic analysis indicate the existence of Albian-Aptian deep marine pelitic sequence interbedded with minor chert and thin quartz sandstone beds that apparently change to a volcanic dominate stratigraphy. Deformed ophiolite-like mafic and ultramafic plutonic rocks and isolated pillow lavas are also exposed to the east in fault contact with the pelitic sequence. The pelitic and interlayered volcanic rocks represent the growth of an extensional Early-Cretaceous basin that followed a Late-Jurassic magmatic quiescence in the Northern Andes. The volcano-sedimentary record is probably related to the growth of a fore-arc basin in a new subduction zone that extends until the Late Cretaceous. The deformation and obduction of the ophiolitic association and the fore-arc basin were probably triggered by the Late Cretaceous collision with an allocthonous plateau-arc associated to the migration of the Caribbean plate.

  8. Petrology and chemistry of late Cretaceous volcanic rocks from the southernmost segment of the Western Cordillera of Colombia (South America)

    Science.gov (United States)

    Spadea, P.; Espinosa, A.

    1996-03-01

    This paper presents new data on the petrology and chemistry of the igneous rocks composing the Mesozoic basement of southernmost Western Cordillera of Colombia along the Ricaurte-Altaquer section. The studied sequence includes variably metamorphosed submarine lavas, breccias, tuffs and dykes of basalt to andesite composition, and minor, shallow quartz microdiorite intrusives. A Campanian age is recorded by radiolarian faunas from chert strata capping the lavas. Two different tholeiitic suites and a younger calc-alkaline suite, represented by hornblende andesite, are distinguished. One tholeiitic suite, represented by plagioclase and pyroxene phyric lavas, evolves from basalt to basaltic andesite. It is characterized by the occurrence of diopsidic pyroxene as early crystallising phase, by depletion in high-field strength elements, particularly Nb and by relative enrichment in light REE and Th. The second tholeiitic suite, which includes aphyric or poorly phyric lavas of basalt to dacite composition, differs from the first group in having moderately low {FeO tot}/{MgO} ratio and lower P 2O 5 content for a given SiO 2, and higher {Ti}/{Zr}and{Y}/{Zr} ratios. The pyroxene chemistry of the two suites also differs. The primary geochemical characteristics of the two suites suggest a similarity with tholeiitic suites generated in island-arc environment. The hornblende andesite has mineralogical and chemical characteristics of calc-alkaline lavas erupted in an oceanic setting in an evolved island-arc. Petrologic and geochemical evidence suggests that the volcanic rocks from the Ricaurte-Altraquer section are similar to the island-arc tholeiite volcanics from the upper Macuchi Formation of northern Ecuador and can be correlated partly with this unit. Conversely, they are petrochemically dissimilar from the typical Diabase Group volcanic rocks, characterized by transitional MORB lavas, extensively present to the north in the Western Cordillera of Colombia.

  9. Petrology of the Upper Border Series of the Skaergaard Intrusion

    Science.gov (United States)

    Salmonsen, L.; Tegner, C.; Jakobsen, J. K.

    2009-12-01

    Layered Series are similar in the early stages of differentiation until after FeTi-oxides appear as primocrysts. In the more evolved rocks the Upper Border Series is gradually enriched in SiO2, K2O and incompatible trace elements relative to the Layered Series as shown by Naslund (1984). This is expressed by abundant interstitial granophyre pockets between the cumulus crystals in the Upper Border Series. However, we find that it is possible to explain the Upper Border Series as a mixture of cumulus minerals and reasonable liquid estimates. Thus the Upper Border Series appears to trap a higher fraction of residual liquid than is the case in the Layered Series. We conclude that the Upper Border Series crystallized from the same liquid as the Layered Series and mainly differs in a high amount of trapped liquid. This implies that the Skaergaard chamber had only one convecting magma body. References: Naslund, H.R.; Petrology of the Upper Border Series of the Skaergaard Intrusion, Journal of Petrology, Vol. 25, Part 1, pp 185-212, 1984

  10. Petrological variability in recent magmatism at Axial Seamount

    Science.gov (United States)

    Dreyer, B. M.; Clague, D. A.; Gill, J. B.

    2011-12-01

    Axial Seamount is known for its compositional homogeneity. We report on petrological variability in lavas from the summit caldera and rims of Axial Seamount during the last ~1.2ka and its implications for shallow crustal magma dynamics. AUVs have mapped the summit at ~1 m resolution, and ROVs have collected numerous lavas and volcaniclastic cores. Geospatial, superpositional, compositional, and age constraint data were used to outline flow units and construct geologic maps. Nearly 200 glasses from summit lavas were analyzed for major elements. A subset of ~20 samples were analyzed for selected trace elements, Pb-, U-, and Th- isotope ratios, and 226Ra and 210Pb. The results a) confirm a high degree compositional homogeneity, b) demonstrate a more restricted range in Pb-isotope ratios than previous data, c) indicate uniform compositional source component(s) genetically linked to that of the Cobb-Eickelberg seamount chain, and d) expand the dataset of distinctly-low 230Th/232Th lavas and subdivide them into geospatial groups. Hundreds of volcaniclastic grains collected from subsurface depths of up to several tens of cm analyzed for major elements extend the record of summit magmatism beyond what is exposed. Summit lava glasses are compositionally N-MORB. Summit volcaniclastics range to higher MgO (+1%); thus, magmatism likely included more mafic episodes than is recorded in the flows as yet sampled or that volcaniclastics preferentially sample higher temperature lavas. Negative correlation of CaO/Al2O3 with MgO in all glasses suggests fractionation from parental melt(s) of plag ± ol but not cpx. K2O/TiO2 ranges are typical for much of the JdFR. Summit lavas range from aphyric to ~35% plag phyric ± a few % ol. Plag-phyric summit lavas tend to have greater MgO (>7.5%), lower CaO/Al2O3 (control, plag-phyric lavas are older than aphyric lavas, the oldest of which is ~1.2ka. Aphyric lavas dominate the southern and far northern caldera, and plag-phyric lavas are

  11. Petrology of upper Eocene-Oligocene plutonic rocks of Moalleman Damghan area

    Science.gov (United States)

    Kohansal, Reza; Zolfaghari, Seddigheh; Hashem Emami, Mohammad

    2010-05-01

    pressure of the hypoabyssal plutons of study area indicate that the formation of these rocks probabely began with the crystallization of plagioclases and amphibole phenocrysts at about 850 to 900 degree centigrade, and the pressure 1 to 3 kbr. The process continued with the crystallization of biotite and quartz at about 700 to 750 degree centigrade and 0.5 to 1 kbr, and terminated by the crystallization of matrix at about 680 degree centigrade and 1 to 1.5 kbr pressure. According to petrological, mineralogical and geochemical specifications genesis of acidic rocks of Moalleman area is interpreted as cordilleran I type granites. Considering the hybridization phenomenon it seems that magmatic genesis of the intermediate rocks is comparable wih hybrid granitoids type.

  12. Petrogenesis of the Main Petrologic and Chronologic Volcanic Phases in the Gharyan Province, NW Libya.

    Science.gov (United States)

    Gafeer, A.; Nabelek, P. I.

    2014-12-01

    Cenozoic Libyan volcanic fields are manifestations of tremendous episodic outpourings of basaltic lavas within the East Saharan Craton. The volcanic fields are confined to a NW-SE trend (N140°E) that stretches from the Mediterranean coast in the north to Tibesti (Libya-Chad border) in the south. The four major volcanic fields (Gharyan, As-Sawda, Al-Haruj, and Nuquay) show a systematic decrease in age starting from ~55 Ma in Gharyan (NW) to the Holocene in Nuquay (SE). This apparent trend in ages along with characteristics resembling oceanic island basalts (OIB's) prompted several authors to attribute their origin to the African plate moving over a hot spot (e.g. Conticelli et al. 1995; Woller and Fediuk 1980; Hegazy 1999). In the Gharyan province (GVP), the igneous activity was indeed episodic and lasted for at least 50 Ma. The large span of ages of these volcanic rocks within the same volcanic field makes the hot spot model at least equivocal. Whole rock analyses for the major petrologic and chronologic units suggest that the basaltic and phonolitic suites within the GVP had different primary sources. The basaltic rocks show smooth REE patterns. LREE/HREE fractionations of the eruptive pulses are inconsistent with their ages, suggesting that they represent different melt fractions generated from the same mantle source. Phonolites show very different REE patterns. The patterns are concave-upward with low TbN/YbN ratios (0.6-0.8). The origin of the GVP basaltic rocks is consistent with melts generated from metasomatized lithospheric mantle across the garnet-spinel transition zone. The most primitive (>7 wt % MgO) basalts were used to model mantle melting processes and indicate 3-10% melting of an amphibole-bearing, spinel/garnet mantle source. Rather than being related to a hot spot, the genesis of the Libyan lavas appears to have been caused by reactivation of lithospheric megastructures with asthenospheric upwelling, in relation to the Africa-Europe convergence.

  13. Petrology and geochemistry of three early Holocene eruptions from Makushin volcano, Alaska

    Science.gov (United States)

    Larsen, J. F.; Schaefer, J. R.

    2016-12-01

    Makushin volcano is an 1800-meter-high stratovolcano with an ice-filled, 2x3 km summit crater, 25 km west of Dutch Harbor and Unalaska, Alaska on Unalaska Island. This study examines the petrology and geochemistry of the three largest, early Holocene eruptions from Makushin: "CFE", (ca. 9000 BP), "Nateekin" (ca. 8700 BP), and "Driftwood" (ca. 8200 BP). The CFE eruption produced thick scoria fall deposits to the northeast and pyroclastic-flow deposits in upper Makushin and "Waterfall" valleys extending >12 km to the east and north. The Nateekin eruption produced fine ash to fine lapilli deposits that are up to 20 cm thick in the Unalaska town area. The Driftwood eruption produced tan pumice and dense, black scoriaceous fall deposits, up to 2 m thick, primarily in the Driftwood valley area to the northeast. Whole rock major (XRF) and trace element (LA-ICPMS) compositions were collected from the CFE and Driftwood samples. Samples from the Nateekin unit were too fine-grained for whole-rock analyses. Analyses of glass, phenocryst, and microlite phases from all three units were collected at UAF using the JEOL JXA-8530F electron microcprobe. The CFE and Driftwood eruptions produced medium K2O, tholeiitic andesites: CFE = 56 to 60 wt. % SiO2; Driftwood = 60 to 63 wt. % SiO2. The three units have andesite to rhyodacite glass compositions: CFE= 57 to 64 wt. % SiO2; Nateekin = 59 to 61 wt. % SiO2; Driftwood = 67 to 70 wt. % SiO2. The CFE and Driftwood samples have plagioclase, clinopyroxene and orthopyroxene phenocrysts, with minor olivine in the CFE fall deposit scoria. The pyroxenes are uniform in composition: Opx = Wo4.6En58.7Fs36.7 (n=58) and Cpx = Wo39.7En41.9Fs18.4 (n=132). Plagioclase phenocrysts from Driftwood pumice have An52-54 cores and An48-49 rims. CFE plagioclase phenocrysts are bimodal, with a lower An50-54 group and a higher An70-89 group. Nateekin glass compositions are similar to CFE scoria analyses from the middle to top of the unit, indicating little

  14. Petrological and Geochemical characterization of central Chihuahua basalts: a possible local sign of rifting activity

    Science.gov (United States)

    Espejel-Garcia, V. V.; Garcia-Rascon, M.; Villalobos-Aragon, A.; Morton-Bermea, O.

    2012-12-01

    The central part of the mexican state, Chihuahua, is the oriental border of the Sierra Madre Occidental (silicic large igneous province), which consist of series of ignimbrites divided into two volcanic groups of andesites and rhyolites. In the central region of Chihuahua, the volcanic rocks are now part of the Basin and Range, allowing the presence of mafic rocks in the lower areas. The study area is located approximately 200 km to the NW of Chihuahua city near to La Guajolota town, in the Namiquipa County. There are at least 5 outcrops of basalts to the west of the road, named Puerto de Lopez, Malpaises, El Tascate, Quebrada Honda, and Carrizalio, respectively. These outcrops have only been previously described by the Mexican Geologic Survey (SGM) as thin basaltic flows, with vesicles filled with quartz, and phenocrystals of labradorite, andesine, oligoclase and olivine. Petrologically, the basalts present different textures, from small phenocrysts of plagioclase in a very fine matrix to large, zoned and sometimes broken phenocrysts of plagioclase in a coarser matrix. All samples have olivine in an advanced state of alteration, iddingsite. The geochemical analyses report that these basaltic flows contain characteristics of rift basalts. The rocks have a normative olivine values from 5.78 to 27.26 and nepheline values from 0 to 2.34. In the TAS diagram the samples straddle the join between basalt and trachy-basalt, reflecting a high K2O content. The Mg# average is 0.297, a value that suggests that the basalts do not come from a primitive magma. The basalts have high values of Ba (945-1334 ppm), Cu (54-147 ppm), and Zn (123-615 ppm). The contents of Rb (23-57 ppm), Sr (659-810 ppm), Y (26-33 ppm), Zr (148-217 ppm) and Cr (79-98 ppm) are characteristics of rift basalts. Using discrimination diagrams, the basalts plot in the field of within plate, supporting the rifting origin. Outcrops of other basalts, at about 80 to 100 km to the east of the study area, Lomas El

  15. Depositional and Stratigraphic Architecture evolution of Deltaic Successions in Different Tectonic Stages: Palaeogene Kongdian and Shahejie Formations, Baxian Sag, East China

    Science.gov (United States)

    Xiaopeng, Li; Hua, Wang

    2017-04-01

    Predicting the distribution of favorable reservoir and evolution of ancient deltaic successions requires the evaluation of the depositional processes and its vertical architecture based on sedimentary facies analysis. This has been applied to a core-based subsurface facies analysis of a deltaic succession in the early to late Palaeogene of Baxian Sag, Bohaiwan Basin, East China. Evolution of three genetically successions with a total thickness of 1000-4000m comprising three depositional systems including fan delta, braid delta and shallow water delta record initial rift phase, rapid rift phase and post rift phase. The initial rift phase consist of several coarsening upward successions, which are mainly conglomerate, pebbly sandstone and coarse sandstone that deposited from root segment, middle segment to front segment of fan delta. The rapid rift phase consist of several fining upward successions developed individual or associated with coarsening upward successions, the former one mainly developed as fluvial-dominated channel fills in deltaic plain and delta front, and the latter one mainly developed in the intersection of distributary channel fill and mouth bar, mainly dominated by wave and influenced by fluvial, with the feature of fine grained sandstone. The post rift phase consist of fining upward successions, interpreted as fluvial-dominated coarse-grained distributary channel fills, and coarsening upward successions, interpreted as wave dominated, fluvial influenced fine-grained sandstone in mouth bar. Delta plain occupied more than 70% of the development area of delta, with features of large-scale cross-bedding, massive bedding. The fan-deltaic to braid-deltaic evolution is represented by an overall upward increase in the distance of progradation, decrease in grain size and increase in wave influence. The following evolution to shallow water delta is represented by an overall upward increase in aggradational succession developed, decrease in paleoslope angle

  16. Petrology and Cosmochemistry of a Suite of R Chondrites

    Science.gov (United States)

    Torrano, Z. A.; Mittlefehldt, D. W.; Peng, Z. X.

    2015-01-01

    Chondrites are among the most primitive surviving materials from the early solar system. They are divided into groups based on chemical types defined by mineralogy, bulk composition, and oxygen isotope compositions. Chondrites range in petrographic grade from type 1 to type 7. Type 3 chondrites are the most primitive and are little changed from the nebular solids accreted to form asteroids. They are composed of chondrules, fine-grained matrix, metal and sulfide, plus or minus Ca-Al-rich inclusions. With increasing aqueous alteration at low temperatures, members of some chondrite classes transformed from type 3 towards type 1. With increasing thermal metamorphism and low fluid content, members of other classes changed from type 3 towards type 7. Rumuruti (R) chondrites are a rare group (0.1% of falls) similar to ordinary chondrites in some properties but different in others. They are characterized by low chondrule/matrix modal abundance ratios, high oxidation state, small mean chondrule size, abundant sulfides and low metal contents. R chondrites vary in petrologic type from 3 to 6. They are important objects to study because some of them have undergone metamorphism at high temperatures in the presence of aqueous fluids. In contrast, CM and CI chondrites were heated to low temperatures in the presence of aqueous fluids leading to alteration; they contain low-T hydrous phases (phyllosilicates) and little or no remaining metal. Ordinary chondrites were heated to high temperatures in a low-fluid environment resulting in anhydrous metamorphic rocks. R6 chondrites are highly metamorphosed and some contain the high-T hydrous phases mica and amphibole. R chondrites are thus unique and give us an opportunity to examine whether there are compositional effects caused by high-T, highfluid metamorphism of nebular materials.

  17. Thermal history of the Earth and its petrological expression

    Science.gov (United States)

    Herzberg, Claude; Condie, Kent; Korenaga, Jun

    2010-03-01

    Non-arc basalts of Archean and Proterozoic age have model primary magmas that exhibit mantle potential temperatures TP that increase from 1350 °C at the present to a maximum of ˜ 1500-1600 °C at 2.5-3.0 Ga. The overall trend of these temperatures converges smoothly to that of the present-day MORB source, supporting the interpretation that the non-arc basalts formed by the melting of hot ambient mantle, not mantle plumes, and that they can constrain the thermal history of the Earth. These petrological results are very similar to those predicted by thermal models characterized by a low Urey ratio and more sluggish mantle convection in the past. We infer that the mantle was warming in deep Archean-Hadean time because internal heating exceeded surface heat loss, and it has been cooling from 2.5 to 3.0 Ga to the present. Non-arc Precambrian basalts are likely to be similar to those that formed oceanic crust and erupted on continents. It is estimated that ˜ 25-35 km of oceanic crust formed in the ancient Earth by about 30% melting of hot ambient mantle. In contrast, komatiite parental magmas reveal TP that are higher than those of non-arc basalts, consistent with the hot plume model. However, the associated excess magmatism was minor and oceanic plateaus, if they existed, would have had subtle bathymetric variations, unlike those of Phanerozoic oceanic plateaus. Primary magmas of Precambrian ambient mantle had 18-24% MgO, and they left behind residues of harzburgite that are now found as xenoliths of cratonic mantle. We infer that primary basaltic partial melts having 10-13% MgO are a feature of Phanerozoic magmatism, not of the early Earth, which may be why modern-day analogs of oceanic crust have not been reported in Archean greenstone belts.

  18. Petrology and In Situ Trace Element Chemistry of a Suite of R Chondrites

    Science.gov (United States)

    Mittlefehldt, D. W.; Peng, Z. X.; Torrano, Z. A.

    2015-01-01

    Rumuruti (R) chondrites are characterized by low chondrule/matrix modal ratios, high oxidation state, small mean chondrule size, abundant sulfides and low metal contents, and are of petrologic types 3 to 6 [1, 2]. LAP 04840 (R5, [3]) and MIL 11207 (R6), contain the high-T hydrous phases amphibole and mica [3, 4]; not all equilibrated R chondrites contain these [2]. R chondrites thus can provide evidence on whether there are compositional effects caused by high-T, high-fluid metamorphism of nebular materials. We are investigating a suite of R chondrites of diverse petrologic grades to further understand the nature of the metamorphic processes that engendered them [5]. We report on our petrological studies, plus preliminary in situ analyses of trace elements in amphibole-bearing R chondrites.

  19. Review and update of the applications of organic petrology: Part 2, geological and multidisciplinary applications

    Science.gov (United States)

    Suarez-Ruiz, Isabel; Flores, Deolinda; Mendonça Filho, João Graciano; Hackley, Paul C.

    2012-01-01

    The present paper is focused on organic petrology applied to unconventional and multidisciplinary investigations and is the second part of a two part review that describes the geological applications and uses of this branch of earth sciences. Therefore, this paper reviews the use of organic petrology in investigations of: (i) ore genesis when organic matter occurs associated with mineralization; (ii) the behavior of organic matter in coal fires (self-heating and self-combustion); (iii) environmental and anthropogenic impacts associated with the management and industrial utilization of coal; (iv) archeology and the nature and geographical provenance of objects of organic nature such as jet, amber, other artifacts and coal from archeological sites; and (v) forensic science connected with criminal behavior or disasters. This second part of the review outlines the most recent research and applications of organic petrology in those fields.

  20. Petrology of the Crystalline Rocks Hosting the Santa Fe Impact Structure

    Science.gov (United States)

    Schrader, C. M.; Cohen, B. A.

    2010-01-01

    We collected samples from within the area of shatter cone occurrence and for approximately 8 kilometers (map distance) along the roadway. Our primary goal is to date the impact. Our secondary goal is to use the petrology and Ar systematics to provide further insight into size and scale of the impact. Our approach is to: Conduct a detailed petrology study to identify lithologies that share petrologic characteristics and tectonic histories but with differing degrees of shock. Obtain micro-cores of K-bearing minerals from multiple samples for Ar-40/Ar-39 analysis. Examine the Ar diffusion patterns for multiple minerals in multiple shocked and control samples. This will help us to better understand outcrop and regional scale relationships among rocks and their responses to the impact event.

  1. Geophysical, petrological and mineral physics constraints on Earth's surface topography

    Science.gov (United States)

    Guerri, Mattia; Cammarano, Fabio; Tackley, Paul J.

    2015-04-01

    Earth's surface topography is controlled by isostatically compensated density variations within the lithosphere, but dynamic topography - i.e. the topography due to adjustment of surface to mantle convection - is an important component, specially at a global scale. In order to separate these two components it is fundamental to estimate crustal and mantle density structure and rheological properties. Usually, crustal density is constrained from interpretation of available seismic data (mostly VP profiles) based on empirical relationships such those in Brocher [2005]. Mantle density structure is inferred from seismic tomography models. Constant coefficients are used to interpret seismic velocity anomalies in density anomalies. These simplified methods are unable to model the effects that pressure and temperature variations have on mineralogical assemblage and physical properties. Our approach is based on a multidisciplinary method that involves geophysical observables, mineral physics constraints, and petrological data. Mantle density is based on the thermal interpretation of global seismic tomography models assuming various compositional structures, as in Cammarano et al. [2011]. We further constrain the top 150 km by including heat-flow data and considering the thermal evolution of the oceanic lithosphere. Crustal density is calculated as in Guerri and Cammarano [2015] performing thermodynamic modeling of various average chemical compositions proposed for the crust. The modeling, performed with the code PerpleX [Connolly, 2005], relies on the thermodynamic dataset from Holland and Powell [1998]. Compressional waves velocity and crustal layers thickness from the model CRUST 1.0 [Laske et al., 2013] offer additional constrains. The resulting lithospheric density models are tested against gravity (GOCE) data. Various crustal and mantle density models have been tested in order to ascertain the effects that uncertainties in the estimate of those features have on the

  2. 松辽盆地钱家店地区姚家组铀储层岩石学特征及成岩作用%Petrology and diagenesis of the uranium reservoir in the Yaojia formation of Songliao Basin,Qianjiadian area

    Institute of Scientific and Technical Information of China (English)

    朱强; 焦养泉; 吴立群; 荣辉; 谢惠丽; 马小东

    2015-01-01

    Based on drill core observation,thin section identification,scanning electron microscopy (SEM)analysis,quantitative statistics and other techniques,the uranium reservoir of the Yaojia formation in the Songliao Basin Qianjiadian area is divided into three types,i.e.ginger-purple oxide sandstone,ore gray sandstone and primary grey sandstone.Additionally,characteristics of ore-containing sandstones and diagenesis process are discussed.Results show that both compositional and structural maturity of the sandstone are low,the average light mineral compositional maturity index only 0.56,SiO2/Al2 O3 is 6.69.The diagenesis in-tensity of uranium bearing rock series is strong,which include compaction,cementation,metasomatism,dissolution and clay mineral transformation.By analyzing intervening relationships of diagenetic minerals,the following diagenetic evolutionary se-quence is determined:framboidal and fine grained pyrite,early calcite cementation (micrite calcite),the secondary overgrowth of quartz,dissolution of clastic particles,secondary mineral formation(clay mineral replacing clastic particles),pore filling calcite (sparry calcite and iron dolomite formation),calcite replacement of clastic particles,biotite hydrolysis,euhedral and anhedral py-rite.This research provides an important discussion on relationships between sandstone uraniferous characteristics and rock com-ponents,and reveal the influence of diagenesis on uranium’s migration and precipitation.%通过岩心观察、薄片鉴定、扫描电镜分析等手段,将松辽盆地钱家店地区姚家组铀储层划分为姜黄色-紫红色氧化砂岩、含矿灰色砂岩、原生灰色砂岩3种类型,并讨论了含矿岩系主要的成岩作用类型,划分了成岩演化序列。研究表明:该区砂岩的成分成熟度和结构成熟度都较低,轻矿物的成熟度指数(Q/(F+R))平均值仅为0.56,SiO2/Al2 O3为6.69;含矿岩系成岩作用较强,主要类型有压实

  3. Sedimentary facies of the Middle-Lower Devonian Niqiuhe Formation in East Ujimqin Qi of Inner Mongolia%内蒙古东乌旗地区中下泥盆统泥鳅河组沉积相研究

    Institute of Scientific and Technical Information of China (English)

    杜叶龙; 程银行; 李艳锋; 李敏; 胡晓佳; 张永; 张天福; 牛文超

    2015-01-01

    发育于内蒙古东乌旗地区的泥鳅河组,属于早中泥盆世沉积,厚度约1000,m,主要发育泥岩、粉砂岩和灰岩沉积,粉砂岩中常常发育大量腕足类和珊瑚生物化石。首次在本区发现风暴沉积和 Beaconites 遗迹化石:风暴沉积由下至上包括粒序层理段、平行层理段、丘状交错层理段和浪成波纹层理段4个层段;Beaconites遗迹化石具管壁和内部水平“V”字型的回填纹构造。通过对岩相、生物化石、风暴沉积和 Beaconites 遗迹化石的研究显示,东乌旗地区泥鳅河组为浅海相沉积。%The Middle-Lower Devonian Niqiuhe Formation,with about 1 000,m thick,developed at the East Ujimqin Qi of Inner Mongolia.It mainly consists of mudstone,siltstone and limestone.A great deal of brachiopoda and coral fossils are often found in the siltstone.Storm deposit and the trace fossil of Beaconites were found for the first time.The storm deposits consist from the bottom to the top of four seg_ments,namely graded bedding,parallel bedding,hummocky cross_bedding and wavy bedding.Beaco-nites is characterized by pipe wall and horizontal “V” back_packing structure.The research of petrofacies, fossils,storm deposits and Beaconites shows that the Niqiuhe Formation in East Ujimqin Qi area belongs to shallow sea facies.

  4. PETROLOGY METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20070226 Chen Nengsong (Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China); Liu Rong LA-ICP-MS U-Pb Zircon Dating for Felsic Granulite, Huangtuling Area, North Dabieshan: Constraints on Timing of Its Protolith and Granulite-Facies Metamorphism, and Thermal Events in Its Provenance (Journal of China University of Geosciences, ISSN1002-0705, CN42-1279/P, 16(4), 2005, p.317-323, 4 illus., 2 tables, 32 refs.) Key words: granulites, Dabie Mountains

  5. PETROLOGY (1)IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>20082204 Cong Feng(Institute of Geochem- istry,Chinese Academy of Sciences,Guiyang 550002,China);Tang Hongfeng Geochem- istry and Tectonic Setting of Devonian Rhyo- lites in Southern Altay,Xinjiang,Northwest China(Geotectonica et Metallogenia,ISSN 1001—1552,CN44—1595/P,31(3),2007, p.359—364,6 illus.,1 table,17 refs.) Key words:rhyolites,Altai Mountains

  6. PETROLOGY (2)METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>20082229 Chen Zhenyu(Institute of Mineral Resources,Chinese Academy of Geological Science,Beijing,100037,China);Yu Jinjie Discussion of the Application of Zr—in—Ru- tile Thermometer in the Sulu-Dabie UHP Eclogites(Acta Geologica Sinica,ISSN 0001—5717,CN11—1961/P,81(10),2007,p. 1369—1378,1 illus.,3 tables,26 refs.) Key words:eclogite,geologic thermome- try,Dable Mountains

  7. Petrologic evolution of CM chondrites: The difficulty of discriminating between nebular and parent-body effects

    Science.gov (United States)

    Kerridge, J. F.; McSween, H. Y., Jr.; Bunch, T. E.

    1994-07-01

    We wish to draw attention to a major controversy that has arisen in the area of CM-chondrite petrology. The problem is important because its resolution will have profound implications for ideas concerning nebular dynamics, gas-solid interactions in the nebula, and accretionary processes in the nebula, among other issues. On the one hand, cogent arguments have been presented that 'accretionary dust mantles,' were formed in the solar nebula prior to accretion of the CM parent asteroid(s). On the other hand, no-less-powerful arguments have been advanced that a significant fraction of the CM lithology is secondary, produced by aqueous alteration in the near-surface regions of an asteroid-sized object. Because most, if not all, CM chondrites are breccias, these two views could coexist harmoniously, were it not for the fact that some of the coarse-grained lithologies surrounded by 'accretion dust mantles' are themselves of apparently secondary origin. Such an observation must clearly force a reassessment of one or both of the present schools of thought. Our objective here is to stimulate such a reassessment. Four possible resolutions of this conflict may be postulated. First, perhaps nature found a way of permitting such secondary alteration to take place in the nebula. Second, maybe dust mantles could form in a regolith, rather than a nebular, environment. Third, it is possible that dust mantles around secondary lithologies are different from those around primary lithologies. Finally, perhaps formation of CM chondrites involved a more complex sequence of events than visualized so far, so that some apparently 'primary' processes postdated certain 'secondary' processes.

  8. Comparative study of hydrographic conditions for algal bloom formation in the coastal waters of east and west of Hong Kong during 1998

    Institute of Scientific and Technical Information of China (English)

    FANG Hongda; TANG Senming

    2009-01-01

    Phytoplankton abundance was found to be positively correlated with seasonal changes of seawater temperature in Port Shelter and Lamma Channel, Hong Kong in 1998. Rising water temperature from around 20°C to 25°C coincided with an increase in phytoplankton abundance at both locations. Heavy rains from June to September reduced salinity from 30 to 20, but the decrease in salinity was not correlated with a decline in phytoplankton abundance. In spring 1998, over 0.6×106 cells dm-3 and 0.1×106 cells dm-3 of the dinoflagellate, Gymnodinium mikimotoi Miyake et Kominami ex Oda occurred in the coastal waters of Port Shelter and Lamma Channel, respectively. High abundance of the dinoflagellate Ceratium furca (Ehr.) Claparede et Lachmann (>1×106 cells dm-3) produced long-lasting blooms in the waters of Port Shelter from September to October in 1998. The abundances of both diatoms and dinoflagellates were significantly lower in the waters of Lamma Channel than those in Port Shelter due to the less frequent blooms in 1998. Hydrographic conditions such as stable water masses and water column stratification were the main reasons for the differences in the algal abundance and bloom frequency found between the two locations since neither of the two areas appeared to be nutrient-limited. This type water condition for the formation of algal bloom in Port Shelter has not been reported previously and it is not a general case for many bays along China's coast where algal bloom occurs as well.

  9. Pliocene Basaltic Volcanism in The East Anatolia Region (EAR), Turkey

    Science.gov (United States)

    Oyan, Vural; Özdemir, Yavuz; Keskin, Mehmet

    2016-04-01

    East Anatolia Region (EAR) is one of the high Plateau which is occurred with north-south compressional regime formed depending on continent-continent collision between Eurasia and Arabia plates (Şengör and Kidd, 1979). Recent studies have revealed that last oceanic lithosphere in the EAR have completely depleted to 20 million years ago based on fission track ages (Okay et al. 2010). Our initial studies suggest that extensively volcanic activity in the EAR peaked in the Pliocene and continued in the same productivity throughout Quaternary. Voluminous basaltic lava plateaus and basaltic lavas from local eruption centers occurred as a result of high production level of volcanism during the Pliocene time interval. In order to better understand the spatial and temporal variations in Pliocene basaltic volcanism and to reveal isotopic composition, age and petrologic evolution of the basaltic volcanism, we have started to study basaltic volcanism in the East Anatolia within the framework of a TUBITAK project (project number:113Y406). Petrologic and geochemical studies carried out on the Pliocene basaltic lavas indicate the presence of subduction component in the mantle source, changing the character of basaltic volcanism from alkaline to subalkaline and increasing the amount of spinel peridotitic melts (contributions of lithospheric mantle?) in the mantle source between 5.5-3.5 Ma. FC, AFC and EC-AFC modelings reveal that the while basaltic lavas were no or slightly influenced by crustal contamination and fractional crystallization, to more evolved lavas such as bazaltictrachyandesite, basalticandesite, trachybasalt might have been important processes. Results of our melting models and isotopic analysis data (Sr, Nd, Pb, Hf, 18O) indicate that the Pliocene basaltic rocks were derived from both shallow and deep mantle sources with different melting degrees ranging between 0.1 - 4 %. The percentage of spinel seems to have increased in the mantle source of the basaltic

  10. 四川盆地南江栖霞组白云岩岩石学、地球化学特征及成因%Petrologic and geochemical characteristics and the origin of dolomites in the Qixia Formation in Nanjiang county of the Sichuan Basin

    Institute of Scientific and Technical Information of China (English)

    李小宁; 黄思静; 黄树光; 黄可可; 袁桃; 罗文

    2016-01-01

    四川盆地南江桥亭剖面中二叠统栖霞组二段灰岩局部白云岩化,基质白云岩主要由非平直晶面他形晶白云石构成,孔洞缝中充填鞍形白云石和结晶方解石,溶解作用主要发生在白云石中。在岩石学研究基础上,综合运用碳氧同位素、元素、包裹体均一化温度、阴极发光测试手段,结合埋藏史、热史以及峨眉山玄武岩喷发非正常地热增温事件,研究了基质白云石和鞍形白云石的特征和成因。研究表明:基质白云石、鞍形白云石和结晶方解石的包裹体均一化温度分别为100~110,130~230,130~230℃;富含基质白云石、鞍形白云石和结晶方解石样品的δ18 OPDB值分别为-4.27‰~-6.28‰,-4.87‰~-5.80‰,-5.16‰~-6.50‰,δ13 CPDB值分别为3.97‰~5.22‰,4.88‰~5.35‰,2.73‰~4.29‰;与基质白云岩相比较,鞍形白云石和结晶方解石的δ18 O值略负,并显示三者碳源为同时期海水。反演的基质白云岩形成流体的δ18 OSMOW值分布在3‰~6‰之间,鞍形白云石δ18 OSMOW主要分布在7‰~14‰之间,盐度均显著高于同期海水,因而两者都是在高温和高盐度的流体中形成的。三者都受到了峨眉山玄武岩喷发活动所引起的热事件影响,高温和高盐度克服了白云石沉淀的动力学屏障,形成交代灰岩的基质白云岩和孔洞缝中充填的鞍形白云石,流体的持续高温和Mg2+的消耗,导致了高温方解石的沉淀,显示热液对碳酸盐岩的改造作用。%Limestones are locally dolomitized in the 2nd member of the Middle Permian Qixia Formation of Qiaoting section, located in Nanjiang county of the Sichuan Basin. Matrix dolomites primarily consist of non⁃planar xenotopic dolomite crystals, and vugs and fractures are filled with saddle dolomites and crystalline calcites. Dissolution occurs mainly in dolomites

  11. Barefoot on Hot Ground: Formation Temperatures of Plio-Pleistocene Soil Carbonates in East Africa Based on the Clumped Isotope in Carbonate (Δ47) Thermometer

    Science.gov (United States)

    Passey, B. H.; Eiler, J. M.; Levin, N. E.; Cerling, T. E.

    2008-12-01

    We utilize the carbonate clumped isotope thermometer to investigate paleoenvironments of human evolution in the Turkana Basin of northern Kenya and southern Ethiopia. Analyses were made using a new automated online peripheral that reduces the human workload and improves the success rate of this analysis. Paleotemperatures for Plio-Pleistocene soil carbonates that formed >50cm below the paleosurface range between ~30°C and 40°C; some of this temperature variation is temporally systematic and coherent across depositional facies. Present day mean annual temperature in this region averages 29°C, and there is very little seasonal variation in average monthly temperature (50 cm depth are strongly buffered against diurnal and short-term (i.e., weeks) temperature variations. Possible explanations for these high temperatures include 1) much higher mean annual or mean seasonal air temperatures during parts of the Plio-Pleistocene, 2) a temporal bias of soil carbonate formation towards short-lived extreme temperature events, 3) nonequilibrium or diagenetic isotope effects, and 4) persistent elevation of soil temperatures relative to air temperatures. A brief deployment of remote temperature sensors near Lake Turkana revealed that soil temperatures were considerably higher than air temperatures. Temperatures at 50 cm depth were stable between 35°C and 37°C; those at 10 cm ranged diurnally between 44°C (day) and 33°C (night). Air temperatures in the shade ranged between 37°C (day) and 26°C (night). These study localities were sparsely vegetated, and the elevated soil temperatures are consistent with surface heating by solar radiation. A survey of previous data reveals that temperatures well above 45°C are common for surfaces receiving direct solar radiation. The relevant boundary condition for soil temperature is therefore surface soil temperature, and not air temperature as might be assumed. The Turkana Basin today is one of the hottest regions on Earth; our results

  12. Provenance and Detrital-Zircon Studies of the Mint Canyon Formation and its Correlation to the Caliente Formation, Southern California

    OpenAIRE

    hoyt, johanna

    2012-01-01

    The Middle Miocene Mint Canyon and Caliente formations represent sedimentation after triple-junction extension in southern California. Sandstone and conglomerate petrology, combined with detrital-zircon analysis, determines provenance of the Mint Canyon and Caliente formations. These data indicate that most detritus is locally derived, rather than being derived from the Chocolate Mountains across the San Andreas fault. The Mint Canyon and Caliente formations received Proterozoic anorthosite-s...

  13. Petrography and petrology of Quaternary volcanic rocks from Ghezel Ghaleh, northwest Qorveh

    Directory of Open Access Journals (Sweden)

    Alireza Bajelan

    2014-10-01

    Full Text Available Introduction In the east and northeast of Sanandaj in the Qorveh-Bijar-Takab axis, there are series of basaltic composition volcanoes with Quaternary age. The study area is part of the Sanandaj-Sirjan zone and is located between 47°52' and 47°57' E longitudes and 35°26 and '35°30' N latitudes. Due to the location of the volcanic cone on Pliocene clastic sediments and Quaternary travertine, the age of these volcanoes is considered to be Quaternary. The cones mostly consist of low scoria, ash, volcanic bombs, lapilli deposits and basaltic lava (Moein Vaziri and Aminsobhani, 1985. Petrological and geochemical studies have been carried out to evaluate Quaternary magmatism in the area and to determine the nature of the lithological characteristics, such as the evaluation of source rocks and magma type, degree of partial melting and the tectonic setting of Ghezel Ghaleh rocks (Moein Vaziri, 1997. Simplified geological map of the study area is characterized by ER-Mapper software. Materials and methods In the course of field studies in the region, 40 samples were taken, 30 thin sections were prepared and polished. XRD analyses were performed on some whole rock samples. All major, minor and trace elements were assessed by ICP-MS at Lab Weft Laboratory in Australia. Results Based on the classification of structural zones, the area is located in the Sanandaj-Sirjan zone, hundred kilometers away from the main Zagros thrust along the NW-SE direction. After early Cimmerian orogeny, andesitic volcanic activity took place (Moein Vaziri and Aminsobhani, 1985. A major secondary mineral in these rocks is iddingsite, formed by hydration and oxidation of the olivine (Shelley, 1993. According to SiO2 against Na2O + K2O (TAS diagram (Irvine and Baragar , 1971 and cationic R1 and R2 diagram (De La Roche et el., 1980, volcanic rocks of the area indicate alkaline series. Discussion To obtain more information on the tectonic setting of these rocks, the Zr/Y-Zr diagram

  14. Petrological and geochemical studies of mantle xenoliths from La Palma, Canary Islands

    Science.gov (United States)

    Janisch, Astrid; Ntaflos, Theodoros

    2015-04-01

    La Palma is the second youngest island, after El Hierro, of the Canary archipelago. The archipelago consists of seven large islands, forming an east-west-trending island chain, and several seamounts. All together they form a volcanic belt of around 800 km length and 450 km width, which presumably comprises roughly the Canary hotspot. The islands are located off the western coast of Morocco, Africa. The distance ranges from 100 km to 500 km. Concurrently with the distance, subaerial volcanism age progresses from the oldest lava in the east to the youngest in the west of the archipelago. Presently, La Palma is in the shield building stage of growth (alongside with El Hierro and Tenerife) and is furthermore the fastest growing island of the Canary archipelago. Historical volcanic eruptions are restricted on the younger islands, La Palma and El Hierro, with the last eruption at the south end of La Palma in 1971. Mantle xenoliths described in this work were collected at the slopes of San Antonio Volcano, Fuencaliente, brought to the surface during the 1677/1678 eruption. The mantle xenolith collection comprises sp-lherzolites, sp-harzburgites and pyroxenites. The texture can be distinguished between coarse-grained matrix and fine-grained veins in various thicknesses, mostly with olivine and pyroxene but also with amphibole, phlogopite as well as apatite. Mineral analyses reveal the existence of primary and secondary ol, cpx and opx. Primary ol has Fo contents of 89.2 to 91.7 and NiO ranging from 0.3 to 0.45 wt.%, whereas secondary ol show Fo values of 78.4 to 91.9 but with NiO below 0.3 wt.%. Primary cpx are predominantly Cr-Diopsides with En48.7-51.9-Wo43.5-44.3-Fs4.1-4.9 and Mg# of 91.5 to 92.4. Secondary cpx, primarily Ti-Augit, display En36.7-44.4-Wo47.7-49.6-Fs6.7-13.0 and Mg# of 75.3 to 90.8. Primary opx compositions are in range of En89.3-90.6-Wo1.3-1.5-Fs8.1-9.3 with Mg# between 90.7 and 92.0. Secondary opx exhibit En88.7-89.2-Wo1.7-1.9-Fs9.1-9.5 and Mg# of 90

  15. Petrology of the Betulia Igneous Complex, Cauca, Colombia

    Science.gov (United States)

    Gil-Rodriguez, Javier

    2014-12-01

    The Betulia Igneous Complex (BIC) is a group of Late-Miocene (11.8 ± 0.2 Ma) hypabyssal intrusions of intermediate to felsic composition located in the SW of the Colombian Andes. These bodies have a calc-alkaline tendency and are related to the subduction of the Nazca plate under the South American plate. Diorites, quartz diorites and tonalities have porphyritic and phaneritic textures and are composed of plagioclase, amphibole, quartz, biotite, and orthoclase. Plagioclase is mainly of andesine-type and the amphiboles were classified mainly as magnesiohornblendes, actinolites, and tschermakites. BIC rocks have a narrow range of SiO2 content (59-67wt%) and exhibit an enrichment of LILE and LREE relative to HFSE and HREE, respectively. These features are attributed to enrichment of LILE from the source and retention of HFSE (mainly Nb, Ta, and Ti) by refractory phases within the same source. The depletion of HREE is explained by fractionation of mineral phases that have a high partition coefficients for these elements, especially amphiboles, the major mafic phase in the rocks. Nevertheless, the fractionation of garnet in early stages of crystallization is not unlikely. Probably all BIC units were generated by the same magma chamber or at least by the same petrologic mechanism as shown by the similar patterns in spider and REE diagrams; fractional crystallization and differentiation processes controlled the final composition of the rocks, and crystallization stages determined the texture. Isotopic compositions of BIC rocks (87Sr/86Sr: 0.70435-0.70511; 143Nd/144Nd: 0.51258-0.51280; 206Pb/204Pb: 19.13-19.31; 207Pb/204Pb: 15.67-15.76; 208Pb/204Pb: 38.93-39.20) indicate a source derived from the mantle with crustal contamination. The model proposed for the BIC consists of fluids from the dehydration of the subducted slab (Nazca plate) and subducted sediments that generated partial melting of the mantle wedge. These basaltic melts ascended to the mantle-crust boundary

  16. Petrology of enstatite chondrites and anomalous enstatite achondrites

    Science.gov (United States)

    van Niekerk, Deon

    2012-01-01

    . The broad importance of these studies lies in documenting the petrology of extraterrestrial materials that reveal the geological history of the young solar system prior to the existence of planets. Furthermore, they serve to identify which mineral assemblages record nebular processes and which record processes on asteroids, so that future studies may select the correct material to address particular questions.

  17. On the Grand Challenges in Physical Petrology: the Multiphase Crossroads

    Science.gov (United States)

    Bergantz, G. W.

    2014-12-01

    Rapid progress in experimental, micro-analytical and textural analysis at the crystal scale has produced an unprecedented record of magmatic processes. However an obstacle to further progress is the lack of understanding of how mass, energy and momentum flux associated with crystal-rich, open-system events produces identifiable outcomes. Hence developing a physically-based understanding of magmatic systems linking micro-scale petrological observations with a physical template operating at the macro-scale presents a so-called "Grand Challenge." The essence of this challenge is that magmatic systems have characteristic length and feedback scales between those accessible by classical continuum and discrete methods. It has become increasingly obvious that the old-school continuum methods have limited resolution and power of explanation for multiphase (real) magma dynamics. This is, in part, because in crystal-rich systems the deformation is non-affine, and so the concept of constitutive behavior is less applicable and likely not even relevant, especially if one is interested in the emergent character of micro-scale processes. One expression of this is the cottage industry of proposing viscosity laws for magmas, which serves as "blunt force" de facto corrections for what is intrinsically multiphase behavior. Even in more fluid-rich systems many of these laws are not suitable for use in the very transport theories they aim to support. The alternative approach is the discrete method, where multiphase interactions are explicitly resolved. This is a daunting prospect given the numbers of crystals in magmas. But perhaps all crystals don't need to be modeled. I will demonstrate how discrete methods can recover critical state behavior, resolve crystal migration, the onset of visco-elastic behavior such as melt-present shear bands which sets the large-scale mixing volumes, some of the general morpho-dynamics that underlies purported rheological models, and transient controls on

  18. The Bucaco Basin (Portugal): Organic petrology and geochemistry study

    Energy Technology Data Exchange (ETDEWEB)

    Flores, D.; Ribeiro, J.; Marques, M.M.; Ribeiro, M.A.; Bobos, I.; de Jesus, A. Pinto [Departamento e Centro de Geologia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Pereira, L.C. Gama; Pina, B. [Departamento de Ciencias da Terra e Centro de Geofisica, Universidade de Coimbra, 3000-272 Coimbra (Portugal)

    2010-04-01

    The Bucaco Basin includes a Carboniferous/Permian sequence that comprises, from bottom to top, the following stratigraphic sequence: Algeriz Formation, Vale da Mo Formation and Monsarros Formation. Algeriz Formation is constituted by deposits of basal breccia with variable thickness and alternating layers of siltstone, mudstone and conglomerate. Vale da Mo Formation corresponds to lacustrine deposits comprising massive red beds in the base, that pass alternatively to silty-mudstones, shales and grey mudstones with organic matter; this formation also includes a thin coal seam. Monsarros Formation includes fluvial conglomeratic deposits prevalent in the base and top, separated by layers of siltstone and mudstone, redder to the top. The Bucaco Basin opens as a pull-apart basin, into the Porto-Coimbra-Tomar shear zone and later is affected by the clockwise (dextral) movement of this N10 W shear zone. The petrographic study of samples from Vale da Mo Formation showed that the organic matter corresponds to a type III kerogen, derived from higher land plants (gas-prone). The thermal maturation level of the strata was determined using random vitrinite reflectance, with values ranging from 0.72% to 0.80% (%Rr). Rock-Eval pyrolysis showed that Vale da Mo Formation is the only one with potential to generate hydrocarbons, an observation consistent with the petrographic characteristics. TOC ranges from 0.08% to 1.52%. Monsarros Formation reported the highest values for S1/TOC index. (author)

  19. Structural petrology of an area near Santiago de Compostela (NW Spain)

    NARCIS (Netherlands)

    Zuuren, van A.

    1970-01-01

    The area around Santiago de Compostela has been subjected to petrological and structural investigations. The rocks present in the mapped area have been divided into two complexes (the Ordenes Complex and the Complex of Santiago de Compostela) on the basis of their petrography, structure and grade of

  20. Geochemistry and petrology of mafic Proterozoic and Permian dykes on Bornholm, Denmark:

    DEFF Research Database (Denmark)

    Holm, Paul Martin; Pedersen, Lise E.; Højsteeen, Birte

    2010-01-01

    More than 250 dykes cut the mid Proterozoic basement gneisses and granites of Bornholm. Most trend between NNW and NNE, whereas a few trend NE and NW. Field, geochemical and petrological evidence suggest that the dyke intrusions occurred as four distinct events at around 1326 Ma (Kelseaa dyke), 1...

  1. Magnetic Petrology of Archean High-Grade Terrains: Window into Deep Crustal Structure and Geodynamic Processes

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The major results about magnetic petrology of Archearn high-grade terrains in the world are reviewed in this article, focusing on the relationship between rock magnetism and deformation, and metamorphism and intensity of magnetization of the lower continental crust. The important problems about the magnetic study of rocks for high-grade terrains are advanced.

  2. Assessment of fire-damaged concrete. Combining metamorphic petrology and concrete petrography

    NARCIS (Netherlands)

    Larbi, J.A.; Nijland, T.G.

    2001-01-01

    Metamorphic petrology is a branch of geology that deals with the study of changes in rocks due changing physio-chemical conditions. As conditions shift in or out of the thermodynamic stability field of phases, new phases may appear whereas others disappear. A basic approach is mapping of so-called

  3. The fine scale seismic structure of an exposed island arc section based on field and petrological constrains

    Science.gov (United States)

    Jagoutz, O. E.

    2011-12-01

    Geological mapping of exposed arc sections is essential to understand and quantify important continental crust forming processes. There is strong evidence that a wide range of crust formation mechanism occurs in arcs but to identify the most important one(s) detailed field observation and geological mapping at various crustal levels and in different exposed arc section that cover a wide range of earth history is essential. Here I present an up dated map of the Kohistan-Ladakh arc (KLA) that is based on field mapping and remote sensing over the last 10 years. Together with petrological constrained intrusions depth and geochemical data the map lets us constrain the 3 D architecture of an intraoceanic arc. This provides the basis to address a wide range of essential questions related to crust formation in oceanic arcs. Here I will focus on the 3D architecture of the KLA and how it compares to seismically imaged active arcs. I used bulk rock compositions to calculate constrained phase diagrams of the main rock types exposed in Kohistan. From the high temperature mineralogical composition seismic properties are calculated and a schematic 3-D seismic image of the Kohistan arc is compared to those from active arcs.

  4. Peat swamps at Giral lignite field of Barmer basin, Rajasthan,Western India: understanding the evolution through petrological modelling

    Institute of Scientific and Technical Information of China (English)

    Prakash K.Singh; P.K.Rajak; M.P.Singh; V.K.Singh; A.S.Naik; Alok K.Singh

    2016-01-01

    The lignite samples collected from Giral lignite field of Barmer basin have been subjected to petrological investigation.The data generated has been discussed to understand the evolution of the paleomires of these lignites.The present study reveals that these low rank C coals are chiefly composed of huminite group macerals,mainly telohuminite and detrohuminite,while liptinite and inertinite group macerals occur in subordinate amounts.Not much variation in the maceral composition from Seam-I to Seam-Ⅷ has been observed.Barmer lignites are characterized by a very high GI (>10) and moderate TPI indicating topogenous mire in the basin which was permanently flooded.The GI and TPI values and the petrography-based facies critical models indicate that these lignites originated mostly under wet forest swamp to clastic marsh having telmatic to limno-telmatic conditions with a moderate rate of subsidence and a very slow fall in ground water table.Further,the GWI and VI values are suggestive of mesotrophic to rheotrophic hydrological conditions having the dominance of herbaceous to marginal aquatic vegetation.There were spells of periodic drowning of peat especially during the formation of Seam-Ⅶ.Moderately high concentration of calcium in these lignites along with the presence of framboidal pyrite indicate enhanced sulphate-reducing bacterial activity present in carbonate and sulphate-rich waters in the basin during peat formation.

  5. High-resolution geology, petrology and age of a tectonically accreted section of Paleoarchean oceanic crust, Barberton greenstone belt, South Africa

    Science.gov (United States)

    Grosch, Eugene; Vidal, Olivier; McLoughlin, Nicola; Whitehouse, Martin

    2015-04-01

    The ca. 3.53 to 3.29 Ga Onverwacht Group of the Barberton greenstone belt (BGB), South Africa records a rare sequence of exceptionally well-preserved volcanic, intrusive and volcani-clastic Paleaoarchean rocks. Numerous conflicting models exist for the geologic evolution and stratigraphy of this early Archean greenstone belt, ranging from plume-type dynamics to modern-style plate tectonics. Although much work has focussed on the komatiites of the ca. 3.48 Ga Komati Formation since their discovery in 1969, far less petrological attention has been given to the younger oceanic rock sequences of the Kromberg type-section in the mid-Onverwacht Group. In this study, we present new field observations from a detailed re-mapping of the Kromberg type-section, and combine this with high-resolution lithological observations from continuous drill core of the Barberton Scientific Drilling Project [1]. The new mapping and field observations are compared to a recent preliminary study of the Kromberg type-section [2]. A U-Pb detrital provenance study was conducted on a reworked, volcani-clastic unit in the upper Kromberg type-section for the first time. This included U-Pb age determination of 110 detrital zircons by secondary ion microprobe analyses (SIMS), providing constraints on maximum depositional age, provenance of the ocean-floor detritus, and timing for the onset of Kromberg ocean basin formation. These new zircon age data are compared to a previous U-Pb detrital zircon study conducted on the structurally underlying sediments of the ca. 3.43 Ga Noisy formation [3]. A multi-pronged petrological approach has been applied to various rock units across the Kromberg, including thermodynamic modelling techniques applied to metabasalts and metapyroxenites for PT-estimates, bulk- and in-situ isotope geochemistry providing constraints on protolith geochemistry and metamorphic history. Consequently, it is shown that this previously poorly studied Kromberg oceanic rock sequence of the

  6. Petrology of the most recent ultrapotassic magmas from the Roman Province (Central Italy)

    Science.gov (United States)

    Gaeta, M.; Freda, C.; Marra, F.; Di Rocco, T.; Gozzi, F.; Arienzo, I.; Giaccio, B.; Scarlato, P.

    2011-11-01

    We report on the newly discovered lava flow that erupted in the Colli Albani Volcanic District, which is the most recent and, geochemically the most peculiar effusive event recognised in the entire ultrapotassic Roman Province (Central Italy). This lava flow is associated with the Monte Due Torri scoria cone, located approximately 5 km south of the Albano hydromagmatic centre (69-36 ka). The Monte Due Torri scoria cone displays well-preserved morphological characteristics and the 40 ± 7 ka age determined for the associated lava flow indicates that its activity was nearly contemporaneous to the most recent, explosive activity that occurred at the Albano centre from 41 to 36 ka. By comparing chemical and petrological features of the Monte Due Torri lava flow, Albano products, and older products (> 69 ka), we show that the youngest Colli Albani eruptions were fed by two new batches of parental magmas that originated in a phlogopite-bearing metasomatised mantle, each one feeding one of the two youngest eruptive cycles (at 69 ka and 41-36 ka). The trace element signature, e.g., very low Pb content, of primitive (MgO > 3 wt.%) magmas feeding the initiation of the hydromagmatic activity at Albano (69 ka) and the subsequent effusive activity at Monte Due Torri (40 ka) indicates that a magma chamber located in the deep anhydrite-bearing dolomite formation was tapped. However, the polygenic activity, the changes in magma composition, and the variable thermometamorphic clasts occurring in the hydromagmatic deposits (recording variable substrata) suggest, particularly for the Albano eruptive centre, a more complex plumbing system consisting of at least two more magma chambers at a shallower depth, i.e., in the Mesozoic limestone and Pliocene pelite formations. The large amount of stratigraphic, volcanological, and geochemical data collected for the Colli Albani Volcanic District, one of the main districts in the ultrapotassic Roman Province, enable us to contribute insights

  7. Petrology of hydrothermal alteration in the Vargeão basaltic impact structure (South Brazil)

    Science.gov (United States)

    Yokoyama, E.; Nédélec, A.; Trindade, R. I.; Baratoux, D.; Berger, G.

    2011-12-01

    Impact cratering process is of primary importance in the evolution of solid bodies of the Solar System. But craters on basaltic rocks, which are the best analog for the surface of other planets and satellites, are rare on Earth. Most studies to date were done in the Lonar crater, a simple crater 1.8 km in diameter, formed on the basaltic flows of the Deccan Province (India). Recently, one medium-size complex crater was identified on volcanic rocks of the Paraná basin (south Brazil) and may provide additional analog to the craters of most rocky planets and satellites. The 12 km wide Vargeão is a very well-preserved impact structure formed on basaltic and subordinately rhyodacites flows of the Serra Geral Formation (about 133-131 Ma), which are locally intertrapped by eolian-sandstones of Botucatu Formation. The impact-related features are represented by shatter cones, breccia-veins and planar deformation features in quartz (few occurrence in the sandstones). This work is focused on the petrogenesis of the centimeter breccia-veins that are found in all lithologies. We conducted a detailed petrological study (petrography, microprobe, SEM, Raman spectroscopy, Spectroscopy of reflectance and XRD) on these veins and their host-rocks. Our results show that the veins were strongly affected by the post-impact hydrothermal fluids. The hydrothermal alteration varies geographically in the structure. On the rim area this alteration consists of total or partial substitution of the melt matrix by quartz, calcite, iron oxides and clay minerals. At the central area, the alteration mineral assembly is composed of quartz, iron oxides, zeolites, clay minerals and rarely calcite. Usually, the alteration shows a zoned setting, which also varies locally. The nature of occurrence of second mineral identified in the context of post-impact hydrothermal alteration of impact craters on basalt represent a critical interpretation to interpret alteration signature of impact craters and the old

  8. Application of Downhole Magnetic Field Measurements in the Identification of Petrological Variations in Basalts, Gabbros and Volcaniclastic Sediments

    Science.gov (United States)

    Bartetzko, A.; Heike, D.

    2002-12-01

    Downhole magnetic field measurements are routinely carried out during many downhole-logging operations for spatial orientation of borehole wall images. The tools used for this purpose, like the Schlumberger General Purpose Inclinometer Tool (GPIT), were not specifically developed for geological interpretations but comparisons with measurements from precise magnetometers show very good correlations. However, systematic value shifts sometimes occur in some holes and this means that data from the GPIT should be used only qualitatively. We show examples from several holes drilled by the ODP demonstrating the potential of magnetic field logs for geologic and petrologic purposes. Variations in the magnetic field data are caused by different geologic processes in these examples. Injections of Fe-Ti-oxide rich gabbros into olivine gabbro of the lower oceanic crust drilled in ODP Holes 735B and 1105A (SW Indian Ridge) cause distinct signals in the magnetic field logs. The vertical resolution of the tool allows detection of thin layers (10 cm minimum thickness) with small anomalies in the magnetic field logs. Cyclicity in eruption processes at mid-ocean ridges can be revealed using the magnetic field logs. Slight petrologic differences between magmas from different eruptions and changes in the Earth?s magnetic field due to reversals, or secular variations in pauses between the eruptions cause characteristic patterns in the logs (e.g. ODP Holes 395A and 418A). Cooling and subsequent alteration processes cause the formation of different types of Fe- and/or Ti-oxide minerals. Typical examples of the formation of secondary magnetic minerals in subaerial lava flows are seen in ODP Hole 1137A (Kerguelen Plateau). Characteristic anomalies in the magnetic field log correlate well with total gamma ray measurement, which is an indicator for alteration in this type of rocks. Grain Size linked with crystallinity variations in basaltic volcaniclastic deposits and debris flows influence

  9. East Asia Rolls On

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The economic recovery in East Asia remains unchanged on its upward trajectory despite the earthquake and devastating tsunami in Japan on March 11.Growth in East Asia slowed after a sharp rebound from the global financial crisis but is improving nonetheless.The World Bank’s East Asia and Pacific Economic Update issued on March 21 projects real GDP growth in East Asia will be smaller than that of 2010 in the following two years.Besides future East Asian economic trends,the report also discusses the impact of the Japanese catastrophe.Edited excerpts follow:

  10. Data-driven Science in Geochemistry & Petrology: Vision & Reality

    Science.gov (United States)

    Lehnert, K. A.; Ghiorso, M. S.; Spear, F. S.

    2013-12-01

    measurements, experiments, and models, both from past and from present studies, and their poor discoverability, interoperability, and standardization. Other deficiencies include the lack of widespread sample curation and online sample catalogs, and broad community support and enforcement of open data sharing policies and a strategy for sustained funding and operation of the cyberinfrastructure. In order to achieve true data-driven science in geochemistry and petrology, one of the primary requirements is to change the way data and models are managed and shared to dramatically improve their access and re-usability. Adoption of new data publication practices, new ways of citing data that ensure attribution and credit to authors, tools that help investigators to seamlessly manage their data throughout the data life cycle, from the point of acquisition to upload to repositories, and population of databases with historical data are among the most urgent needs. The community, especially early career scientists, must work together to produce the cultural shift within the discipline toward sharing of data and knowledge, virtual collaboration, and social networking. Dziewonski, A M, & Anderson, D L: Physics of the Earth and Planet Interiors 25 (4), 297 (1981) Hey, T, Tansley, S, Tolle, K (Eds.): Redmond, VA: Microsoft Research (2009) Zindler, A, & Hart, S R: Ann. Rev. Earth Plan. Sci. 14, 493 (1986)

  11. Petrological and two-phase flow modelling of deep arc crust: insights on continental crust formation

    Science.gov (United States)

    Riel, Nicolas; Bouilhol, Pierre; van Hunen, Jeroen; Cornet, Julien

    2017-04-01

    The genesis of felsic crust is generally attributed to two main processes: the differentiation of primary magmas by crystallization within the crust or uppermost mantle and the partial melting of older crustal rocks. The Mixing/Assimilation/Hybridization of these magmas in the deep crust (MASH zone) and their subsequent segregation constitutes the principal process by which continents have become differentiated into a more mafic, residual lower crust and a more felsic and hydrated upper crust. Although this model describes qualitatively how continental crust forms, little is known on the physical and chemical mechanisms occurring at the root of volcanic arcs. To assess the dynamics of partial melting, melt injection and hybridization in the deep crust, a new 2-D two-phase flow code using finite volume method has been developed. The formulation takes into account: (i) melt flow through porosity waves/channels, (ii) heat transfer, assuming local thermal equilibrium between solid and liquid, (iii) thermodynamic modelling of stable phases and (iv) injection of mantle-derived melt at the Moho. Our parametric study shows that pressure, heat influx and melt:rock ratio are the main parameters controlling the volume and composition of differentiated magma. Overall the composition of segregated products scatters in two groups: felsic (80-68% SiO2) and intermediate (60-52% SiO2), with an average andesitic composition. The bimodal distribution is controlled by amphibole which buffer the composition of segregated products to high SiO2-content when stable. As the amphibole-out melting reaction is crossed segregated products become intermediate. When compared to available geological evidence, the liquid line of descent of mantle-derived magma do not fit the Mg# versus silica trends of exposed volcanic arcs. Instead our modelling results show that reactive flow of those same magma through a mafic crust is able to reproduce such trends.

  12. The lithosphere-asthenosphere system beneath Ireland from integrated geophysical-petrological modeling II: 3D thermal and compositional structure

    Science.gov (United States)

    Fullea, J.; Muller, M. R.; Jones, A. G.; Afonso, J. C.

    2014-02-01

    The lithosphere-asthenosphere boundary (LAB) depth represents a fundamental parameter in any quantitative lithospheric model, controlling to a large extent the temperature distribution within the crust and the uppermost mantle. The tectonic history of Ireland includes early Paleozoic closure of the Iapetus Ocean across the Iapetus Suture Zone (ISZ), and in northeastern Ireland late Paleozoic to early Mesozoic crustal extension, during which thick Permo-Triassic sedimentary successions were deposited, followed by early Cenozoic extrusion of large scale flood basalts. Although the crustal structure in Ireland and neighboring offshore areas is fairly well constrained, with the notable exception of the crust beneath Northern Ireland, the Irish uppermost mantle remains to date relatively unknown. In particular, the nature and extent of a hypothetical interaction between a putative proto Icelandic mantle plume and the Irish and Scottish lithosphere during the Tertiary opening of the North Atlantic has long been discussed in the literature with diverging conclusions. In this work, the present-day thermal and compositional structure of the lithosphere in Ireland is modeled based on a geophysical-petrological approach (LitMod3D) that combines comprehensively a large variety of data (namely elevation, surface heat flow, potential fields, xenoliths and seismic tomography models), reducing the inherent uncertainties and trade-offs associated with classical modeling of those individual data sets. The preferred 3D lithospheric models show moderate lateral density variations in Ireland characterized by a slightly thickened lithosphere along the SW-NE trending ISZ, and a progressive lithospheric thinning from southern Ireland towards the north. The mantle composition in the southern half of Ireland (East Avalonia) is relatively and uniformly fertile (i.e., typical Phanerozoic mantle), whereas the lithospheric composition in the northern half of Ireland (Laurentia) seems to vary

  13. Organic geochemical study of sequences overlying coal seams: example from the Mansfield Formation (Lower Pennsylvania), Indiana

    Energy Technology Data Exchange (ETDEWEB)

    Mastalerz, M.; Stankiewicz, A.B.; Salmon, G.; Kvale, E.P.; Millard, C.L. [Indiana University, Bloomington, IN (United States). Indiana Geological Survey

    1997-09-01

    Roof successions above two coal seams from the Mansfield Formation (Lower Pennsylvanian) in the Indiana portion of the Illinois basin were studied with regard to sedimentary structures, organic petrology and organic geochemistry. The succession above the Blue Creek Member of the Mansfield Formation is typical of the lithologies covering low-sulphur coals ({lt} 1%) in the area studied, whereas the succession above the unnamed Mansfield coal is typical of high-sulphur coal({gt} 2%). The transgressive-regressive packages above both seams reflect the periodic inundation of coastal mires by tidal flats and creeks. Geochemistry and petrology of organic facies above the Blue Creek coal suggest that tidal flats formed inland in fresh-water environments. Above the unnamed coal, trace fossils and geochemical and petrological characteristics of organic facies suggest more unrestricted seaward depositional. 55 refs., 11 figs., 3 tabs.

  14. Geochemical,Petrological and Mineralogical Investigation of Nickeliferous Laterite Goynukbelen, Turkey.

    Science.gov (United States)

    Kabiru, Mohammed; Kumral, Mustafa; Kocaturk, Huseyin; Gumus, Lokman; Kaya, Mustafa

    2017-04-01

    The obduction and tectonically emplacement of ophiolite during late Cretaceous in the Goynukbelen terrane has acted as a potential source for the enrichment of nickeliferous laterite. These ultramafic rocks are highly susceptible to intense chemical and mechanical weathering which are very unstable at surface environment. The lithologies of the rock unit consist of Dunite and peridotite which are unstable and metamorphosed serpentinite and lizardite which are stable ore forming minerals. The laterite is formed as a result of weathering of the above rock types with interplaying role of climate and topography. The terrane provides the ingredients for the association of laterites. The geochemical, petrological and mineralogical associations of low grade laterite samples that are related to nickeliferous mineralization, the lithological profile of the area were studied looking at the different possible areas of enrichment of such a deposit. Weathering of olivine rich ultramafic rocks result in the breakdown of Magnesium and Silica which are replaced in the lattice with Nickel and Iron are precipitate as ferric hydroxide which form oxide deposit. Nickel bearing mineralogy, hydrous magnesium silicate, smectite, Violarite which is a supergene sulfide mineral that indicate weathering and oxidation of primary pentladite, ullmannite which replaces awaruite in it mineral form, Nickeline,Trevorite, Rammelsbergite and gerdoffite also seen. Petrographic indication shows that serpentinization benefic the Nickeliferous ore forming process as they provide adequate texture and porosity for water channel that facilitate the hydrolysis which breakdown silica, increasing the instability of the rock while paving a way for the formation of lizardite which is an ore forming mineral. From the geochemical analyses the Nickel concentration ranges from 1000-4000PPM. Nickeliferous laterite indicates a supergene enrichment which is favour by the ultramafic parent rock, climate and topography

  15. Petrological, geochemical and isotopic characteristics of the Collo ultramafic rocks (NE Algeria)

    Science.gov (United States)

    Laouar, Rabah; Satouh, Adel; Salmi-Laouar, Sihem; Abdallah, Nachida; Cottin, Jean-Yves; Bruguier, Olivier; Bosch, Delphine; Ouabadi, Aziouz; Boyce, Adrian J.; Fallick, Anthony E.

    2017-01-01

    The ultramafic rocks of the Collo region in northeastern Algeria crop out as "stratified" masses that cut across older metamorphic formations of the Petite Kabylie basement. Based on petrological compositions and mineralogical observations, these rocks are mainly peridotites and serpentinites. The peridotites are identified as lherzolites, but dunites may occur rarely. The lherzolites are composed of olivine, orthopyroxene, clinopyroxene and chromian spinel. Their chemical composition shows high MgO (34.4-37.5 wt%), Cr (0.14-0.27 wt%), Ni (0.14-0.26 wt%) and Co (34-133 ppm) contents and low CaO and Al2O3 concentrations (0.02-2.2 wt% and 0.5 to 2.8 wt%, respectively). The chromite, which represents approximately 1-3% of the rock, is ubiquitous and shows two different generations: primary millimetric euhedral crystals and secondary fine xenomorphic grains and interstitial aggregates. The primary chromites are alumino-ferro-magnesian crystals that show high Al2O3 (25.77%-27.36%) and MgO (10.70%-13.36%). Cr# (100 × Cr/(Al + Cr)) ranges from 45 to 48, and Mg# (100 × Mg/(Mg + Fe2+)) from 49 to 59. The secondary interstitial grains are iron-rich chromites. They show low Al2O3 (4.67%-9.54%) and MgO (4.60%-4.65%). Cr# is relatively high (77-88), whereas Mg# shows relatively low values, ranging from 22 to 25. Primary chromite and whole-rock chemistry show that the Collo ultramafic rocks belong to Alpine-type peridotites that were emplaced within an orogenic setting. The oxygen isotopic composition of both peridotites and chromites is consistent with their derivation from a mantle source (δ18O ranges from +3.0 to +5.9‰). Low δ18O values (<+4.4‰) are recorded in serpentinites and are attributed to the effect of serpentinization processes through high-temperature metasomatic fluids. Magnesite-bearing serpentinites show the lowest δ18O values. These are interpreted as the result of surface water input.

  16. The role of petrology in defining volcanic hazards and designing monitoring systems

    Science.gov (United States)

    Smith, I. E.; Turner, M. B.; Price, R. C.; Cronin, S. J.

    2011-12-01

    Petrology is the study of magmatic systems; physical volcanology investigates processes of eruption. Physical volcanology provides the pre-eminent underpinning of the practical business of defining hazard scenarios, planning mitigation and designing monitoring strategies. Recent research in a variety of volcanic settings has demonstrated an important link between the petrologic processes that at a fundamental level drive the behavior of volcanoes and the processes that determine the eruptive style of a volcano. Together these define the hazards that arise from volcanic eruptions. Petrological studies of volcanoes are typically based on a study of lava because coherent rock is less vulnerable to weathering and alteration and is more durable in the geological record. Pyroclastic materials are commonly friable and glassy, are more easily eroded, and are more difficult to use in the analytical techniques that have become the staple basis of petrological studies. However, pyroclastic materials represent a complementary but different part of the magmatic story and it is only by integrating both effusive and explosive components of an eruption sequence that a complete picture of the behavior of the system feeding a volcano can be gained. Andesitic strato-cones are made up of a cone-building facies consisting mainly of primary magmatic products and usually dominated by lava flows because pyroclastic material is easily eroded from the slopes of a steep cone. The surrounding ring plain facies includes primary pyroclastic deposits but is typically dominated by redistributed material in the form of debris flow and lahar deposits together with reworked fluvial material. The deposits of each of these two facies are assembled on different time scales and they contain different aspects of the record of the evolution of the magmatic system that gave rise to them. An important practical consequence of this is that different parts of the geochemical record of the system can occur in

  17. Radioelemental, petrological and geochemical characterization of the Bundelkhand craton, central India: implication in the Archaean geodynamic evolution

    Science.gov (United States)

    Ray, Labani; Nagaraju, P.; Singh, S. P.; Ravi, G.; Roy, Sukanta

    2016-06-01

    We have carried out radioelemental (232Th, 238U, 40K), petrological and geochemical analyses on granitoids and gneisses covering major rock formations of the Bundelkhand craton, central India. Our data reveal that above characteristics are distinct among granitoids (i.e. pink, biotite and grey granitoids) and gneisses (i.e. potassic and sodic types). Pink granitoid is K-feldspar-rich and meta-aluminous to per-aluminous in character. Biotite granitoid is meta-aluminous in character. Grey granitoid is rich in Na-feldspar and mafic minerals, granodiorite to diorite in composition and meta-aluminous in character. Among these granitoids, radioelements (Th, U, K) are highest in pink granitoid (45.0 ± 21.7 ppm, 7.2 ± 3.4 ppm, 4.2 ± 0.4 %), intermediate in biotite granitoid (44.5 ± 28.2 ppm, 5.4 ± 2.8 ppm, 3.4 ± 0.7 %) and lowest in grey granitoid (17.7 ± 4.3 ppm, 4.4 ± 0.6 ppm, 3.0 ± 0.4 %). Among gneisses, potassic-type gneisses have higher radioelements (11.8 ± 5.3 ppm, 3.1 ± 1.2 ppm, 2.0 ± 0.5 %) than the sodic-type gneisses (5.6 ± 2.8 ppm, 1.3 ± 0.5 ppm, 1.4 ± 0.7 %). Moreover, the pink granitoid and the biotite granitoid have higher Th/U (6 and 8, respectively) compared to the grey granitoid (Th/U: 4), implying enrichment of Th in pink and biotite granitoids relative to grey granitoid. K/U among pink, biotite and grey granitoids shows little variation (0.6 × 104, 0.6 × 104, 0.7 × 104, respectively), indicating relatively similar increase in K and U. Therefore, mineralogical and petrological data along with radioelemental ratios suggest that radioelemental variations in these lithounits are mainly related to abundances of the radioactive minerals that have formed by the fractionation of LILE from different magma sources. Based on present data, the craton can be divided into three distinct zones that can be correlated with its evolution in time and space. The central part, where gneisses are associated with metavolcanics of greenstone belt, is

  18. Petrologic perspectives on tectonic evolution of a nascent basin (Okinawa Trough) behind Ryukyu Arc:A review

    Institute of Scientific and Technical Information of China (English)

    YAN Quanshu; SHI Xuefa

    2014-01-01

    Okinawa Trough is a back-arc, initial marginal sea basin, located behind the Ryukyu Arc-Trench System. The formation and evolution of the Okinawa Trough is intimately related to the subduction process of the Philippine Sea Plate beneath the Eurasian Plate since the late Miocene. The tectonic evolution of the trough is similar to other active back-arcs, such as the Mariana Trough and southern Lau Basin, all of which are experiencing the initial rifting and subsequent spreading process. This study reviews all petrologic and geochemical data of mafic volcanic lavas from the Okinawa Trough, Ryukyu Arc, and Philippine Sea Plate, combined with geophysical data to indicate the relationship between the subduction sources (input) and arc or back-arc magmas (output) in the Philippine Sea Plate-Ryukyu Arc-Okinawa Trough system (PROS). The results obtained showed that several components were variably involved in the petrogenesis of the Oki-nawa Trough lavas:sub-continental lithospheric mantle underlying the Eurasian Plate, Indian mid-oceanic ridge basalt (MORB)-type mantle, and Pacific MORB-type mantle. The addition of shallow aqueous fluids and deep hydrous melts from subducted components with the characteristics of Indian MORB-type mantle into the mantle source of lavas variably modifies the primitive mantle wedge beneath the Ryukyu and sub-continental lithospheric mantle (SCLM) beneath the Okinawa Trough. In the northeastern end of the trough and arc, instead of Indian MORB-type mantle, Pacific MORB-type mantle dominates the magma source. Along the strike of the Ryukyu Arc and Okinawa Trough, the systematic variations in trace element ratios and isotopic compositions reflect the first-order effect of variable subduction input on the magma source. In general, petrologic data, combined with geophysical data, imply that the Okinawa Trough is experiencing the“seafloor spreading”process in the southwest segment,“rift propagation”process in the middle seg-ment, and

  19. Petrological imaging of the Cordilleran lithosphere beneath Craven Lake, NCVP, BC, Canada: local evidence for a texturally diverse, hydrous lithosphere

    Science.gov (United States)

    Miller, Christine; Edwards, Benjamin R.; Russell, James K.; Peterson, Nils

    2010-05-01

    Peridotite and pyroxenite xenoliths from the glaciovolcanic Craven Lake center (Edwards et al., 2006) provide local evidence for a texturally diverse, hydrous lithosphere beneath the Stikine terrane, in the Canadian Cordilleran lithosphere. Although the xenolith suite is dominated by spinel lherzolite, websterite and Ol websterite xenoliths also occur. Veins of amphibole, with local apatite, have so far been found in one spinel lherzolite and one websterite xenolith. Although interstitial amphibole has been reported from at least two localities in the northern Cordillera, we believe that this is the first documented occurrence of an amphibole vein in lithospheric peridotite and pyroxenite. Textural analysis shows that the xenoliths from Craven Lake are on average finer grained (~2.0 mm) and less equigranular than xenolith suites from localities to the north (e.g. Harder and Russell, 2005) or to the south (e.g. Peslier et al., 2002). Clinopyroxene-orthopyroxene geothermometry of a peridotite sample indicates that the temperatures of equilibration (964-1022C at 0.1 GPa) are well within the established stability limits of amphibole at lithospheric pressures. Observations on the Craven Lake suite have important implications for the petrology of the Cordilleran lithosphere. Textural observations confirm that the lithosphere beneath the accreted terranes in British Columbia is distinctly heterogeneous, which is consistent with at least local lithospheric variation that could be due in part to tectonism during Mesozoic terrane accretion. Documentation of veins of amphibole plus apatite in the Cordilleran lithosphere is consistent with the Francis and Ludden (1995) hypothesis that the veins could be lithospheric sources for volumetrically minor but spatially wide-spread nephelinite throughout the Canadian Cordilleran, which were remelted during Neogene to Recent, extension-related magmatism. The formation of the veins may be linked to Mesozoic subduction zone metasomatism

  20. Petrology of periodotites as a tool of insight into mantle processes: a review. Jobu mantle kanrangan no gansekigaku (ikani mantle process wo yomitoruka)

    Energy Technology Data Exchange (ETDEWEB)

    Arai, S. (Kanazawa University, Ishikawa (Japan). Faculty of Science)

    1992-09-05

    Petrological studies of the upper mantle materials are reviewed mainly in terms of recent topics. Along with on increase in depletion degree (degree of slipped-out magma) of resistate which remains after magma slipped out from the upper mantle materials, a series from lherzolite to Harzburgites is obtained and as an example, the Horoman peridotite complex which intrudes into the Hidaka metamorphic belt (Hokkaido) is shown. In this connection, a theory is introduced where the bedded structure of this peridotite complex was formed by a series of processes accompanied by the cracks generated in the mantle peridotite. Then, the following topics are explained: strongly incompatible trace elements can be enriched in resistate with high depletion degree (REE paradox); and the recent research trend on issues which relates to the interaction between the magma and mantle, such as the formation of dunites, the origin of picrite basalt, and the origin of chromitite are described. 40 refs., 13 figs.

  1. Fractal approach in petrology: Small-angle neutron scattering experiments with volcanic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lucido, G.; Triolo, R.; Caponetti, E.

    1988-11-01

    Following Mandelbrot's pioneering work in 1977, we attempt to use the concept of fractal dimension in petrology. Fractal dimension is an intensive property of matter which offers a quantitative measure of the degree of surface roughness. Neutron scattering experiments have been performed on 18 volcanic rocks from different localities. The scattered intensity as a function of the momentum transfer obeys a power law whose exponent varies, for the rock samples presented, between -3 and -4. We conclude that, at the molecular level, our volcanic rocks are not fractal volumes. With regard to the particle-matrix interface, it is not possible to provide a determination at the present stage of research. Our findings suggest it is feasible to verify the degree of surface irregularity at a resolution which is relevant to many aspects of petrology.

  2. DEEP-LEVEL GEODYNAMICS: BOUNDARIES OF THE PROCESS ACCORDING TO GEOCHEMIC AND PETROLOGIC DATA

    Directory of Open Access Journals (Sweden)

    Alexei V. Ivanov

    2015-09-01

    Full Text Available Geochemical features for volcanic rocks and petrologic data for deep-seated inclusions, which can be used to infer mass transfer between different geospheres, are reviewed. It is typically believed that slabs can subduct as deep as the core-mantle boundary with the following recycling by plumes coming up to the sublithospheric regions of magma generation. However, the petrologic evidence of the deepest accessible material is limited by the depth of the uppermost lower mantle (~650–700km, i.e. by the depth of the deepest earthquakes. Ferropericlase inclusions in some diamonds do not exclude involvement of deeper mantle horizons, yet do not unambiguously support it. No unambiguous confirmation of involvement of the lower mantle into magma generation underneath volcanically active regions is obtained from geochemical data either, while the geochemical data suggest complete chemical isolation of the Earth’s core from the upper mantle processes.

  3. PETRO.CALC.PLOT, Microsoft Excel macros to aid petrologic interpretation

    Science.gov (United States)

    Sidder, Gary B.

    1994-07-01

    PETRO.CALC.PLOT is a package of macros which normalizes whole-rock oxide data to 100%, calculates the cation percentages and molecular proportions used for normative mineral calculations, computes the apices for ternary diagrams, determines sums and ratios of specific elements of petrologic interest, and plots 33 X-Y graphs and five ternary diagrams. PETRO.CALC.PLOT also may be used to create other diagrams as desired by the user. The macros run in Microsoft Excel 3.0 and 4.0 for Macintosh computers and in Microsoft Excel 3.0 and 4.0 for Windows. Macros provided in PETRO.CALC.PLOT minimize repetition and time required to recalculate and plot whole-rock oxide data for petrologic analysis.

  4. Mineralogy, petrology and chemistry of ANT-suite rocks from the lunar highlands

    Science.gov (United States)

    Prinz, M.; Keil, K.

    1977-01-01

    Anorthositic-noritic-troctolitic (ANT) rocks are the oldest and most abundant rocks of the lunar surface, and comprise about 90% of the suite of the lunar highlands. Consideration is given to the mineralogy, petrology, bulk chemistry, and origin of ANT-suite rocks. Problems associated in classifying and labeling lunar highland rocks because of textural complexities occurring from impact modifications are discussed. The mineralogy of ANT-suite rocks, dominated by plagioclase, olivine and pyrozene, and containing various minor minerals, is outlined. The petrology of ANT-suite rocks is reviewed along with the major element bulk composition of these rocks, noting that they are extremely depleted in K2O and P2O5. Various models describing the origin of ANT-suite rocks are summarized, and it is suggested that this origin involves a parental liquid of high-alumina basalt with low Fe/Fe+Mg.

  5. MinChem: A Prototype Petrologic Database for Hanford Site Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Mackley, Rob D.; Last, George V.; Serkowski, John A.; Middleton, Lisa A.; Cantrell, Kirk J.

    2010-09-01

    A prototype petrologic database (MinChem) has been under continual development for several years. MinChem contains petrologic, mineralogical, and bulk-rock geochemical data for Hanford Site sediments collected over multiple decades. The database is in relational form and consists of a series of related tables modeled after the Hanford Environmental Information System HEIS (BHI 2002) structures. The HEIS-compatible tables were created in anticipation of eventual migration into HEIS, or some future form of HEIS (e.g. HEIS-GEO). There are currently a total of 13,129 results in MinChem from 521 samples collected at 381 different sampling sites. These data come from 19 different original source documents published and unpublished (e.g. letter reports) between 1976 and 2009. The data in MinChem consist of results from analytical methods such as optical and electron microscopy, x-ray diffraction, x-ray fluorescence, and electron probe microanalysis.

  6. Mineralogy, Petrology, Chronology, and Exposure History of the Chelyabinsk Meteorite and Parent Body

    Science.gov (United States)

    Righter, K.; Abell, P.; Agresti, D.; Berger, E. L.; Burton, A. S.; Delaney, J. S.; Fries, M. D.; Gibson, E. K.; Harrington, R.; Herzog, G. F.; Keller, L. P.; Locke, D.; Lindsay, F.; McCoy, T. J.; Morris, R. V.; Nagao, K.; Nakamura-Messenger, K.; Niles, P. B.; Nyquist, L.; Park, J.; Peng, Z. X.; Shih, C. Y.; Simon, J. I.; Swisher, C. C., III; Tappa, M.

    2015-01-01

    The Chelyabinsk meteorite fall on February 15, 2013 attracted much more attention worldwide than do most falls. A consortium led by JSC received 3 masses of Chelyabinsk (Chel-101, -102, -103) that were collected shortly after the fall and handled with care to minimize contamination. Initial studies were reported in 2013; we have studied these samples with a wide range of analytical techniques to better understand the mineralogy, petrology, chronology and exposure history of the Chelyabinsk parent body.

  7. Massive atmospheric sulfur loading of the AD 1600 Huaynaputina eruption and implications for petrologic sulfur estimates.

    OpenAIRE

    Costa Rodriguez, Fidel; Scaillet, Bruno; Gourgaud, Alain

    2003-01-01

    International audience; We combine petrological, analytical, and thermodynamical data to constrain the sulfur yield of the AD 1600 Huaynaputina eruption which has been associated with the largest Earth's temperature shift in the last 600 years. The calculated amount of S (26–55 Tg), partly overlaps, but ranges to almost twice the amount estimated from ice-core data (16–32 Tg), the higher values of our estimate probably reflect that not all S released by the eruption reached the stratosphere. ...

  8. Petrology and geochronology of eclogites from the Variscan Schwarzwald (F.R.G.)

    OpenAIRE

    Kalt, Angelika; Hanel, Michael; Schleicher, Helmut; Kramm, Ulrich

    2006-01-01

    The Moldanubian basement of the Schwarzwald contains basic to ultrabasic rocks of both crustal and mantle origin which display high-pressure mineral assemblages or relics of such. In order to constrain the P-T-t evolution of the crustal high-pressure rocks, petrological and geochronological studies have been carried out on three eclogite samples. Geothermobarometric estimations indicate minimum metamorphic pressures of 1.6 GPa and equilibration temperatures of 670 750°C. Reaction textures doc...

  9. Taos Plateau Volcanic Project: A Vehicle for Integration of Concepts in Igneous Petrology

    Science.gov (United States)

    Henry, D.; Dutrow, B.

    2003-12-01

    Integrating concepts of igneous petrology is generally a challenge, but can be effective in the context of a project based on actual field, geochemical and geochronological data. The final lab project in the igneous portion of petrology involves a series of volcanic and associated rock samples that were collected from the Taos Plateau Volcanic Field, New Mexico, USA. Samples were collected over an area of several tens of km2 throughout the Plateau and represent a spatially and temporally correlated rock suite related to continental rifting. Rift-related magmatism encompasses much of the diversity of terrestrial magma types. Compositions of mafic magmas range from tholeiite to some of the most silica-undersaturated magmas found on the continents. Large effusive eruptions from fissures are typical of some rifts, whereas others may be dominated by central vent cones or even silicic caldera complexes. The injection of mantle-derived magma in extending crust may have a profound effect on the rheology of the crust and, therefore, the style of deformation associated with extension. Most of these aspects of rift volcanism and a wide range of mafic to silicic magma compositions are represented in the Rio Grande rift and the volcanic rocks of the Taos Plateau. In addition, much published data exists for whole rock and trace element geochemistry as well as geochronology. Rock samples and associated information are presented so that the student must integrate multiple lines of evidence, petrographic, petrologic, geochemical and geochronological data in a geospatial framework, to establish a geologic history of the region. The student must also draw on skills learned in mineralogy and structural geology furthering core geoscience education. Subsequent to the petrology course, the students visit the Taos Plateau Volcanic Field during their required field camp, thus reinforcing the linkage between the classroom setting and geologic reality.

  10. Petrology and Geochemistry of New Paired Martian Meteorites Larkman Nunatak 12240 and Larkman Nunatak 12095

    Science.gov (United States)

    Funk, R. C.; Peslier, A. H.; Brandon, A. D.; Humayun, M.

    2016-01-01

    Two of the latest Martian meteorites found in Antarctica, paired olivine-phyric shergottites LAR 12240 and LAR 12095, are described in order to decipher their petrological context, and place constraints on the geological history of Mars. This project identifies all phases found in LAR 12240 and 12095 and analyzes them for major and trace elements. The textural relationships among these phases are examined in order to develop a crystallization history of the magma(s) that formed these basalts.

  11. A new petrological and geophysical investigation of the present-day plumbing system of Mount Vesuvius

    OpenAIRE

    Pommier, Anne; Tarits, Pascal; Hautot, Sophie; Pichavant, Michel; Scaillet, Bruno; Gaillard, Fabrice

    2010-01-01

    Article in Press; International audience; A model of the electrical resistivity of Mt. Vesuvius has been elaborated to investigate the present structure of the volcanic edifice. The model is based on electrical conductivity measurements in the laboratory, on geophysical information, in particular, magnetotelluric (MT) data, and on petrological and geochemical constraints. Both 1-D and 3-D simulations explored the effect of depth, volume and resistivity of either one or two reservoirs in the s...

  12. Petrological differentiation patterns and geomorphic distribution of ferricretes in Central Africa

    OpenAIRE

    BEAUVAIS, Anicet; Roquin, C.

    1996-01-01

    Geomorphic distribution and petrological differentiation patterns of ferricretes widespread on landsurfaces were studied in the Dembia-Zemio area, southeastern Central African Republic. Four types of ferricretes are distributed on high plateaux, hillslopes and low plateaux. The main contrast corresponds to the differentiation between ferricretes of high plateaux rich in poorly hydrated minerals, hematite and kaolinite, and those covering hillslopes and low plateaux richer in hydrated minerals...

  13. The petrological relationship between Kamen volcano and adjacent volcanoes of Klyuchevskaya group

    Science.gov (United States)

    Churikova, Tatiana; Gordeychik, Boris; Wörner, Gerhard; Ivanov, Boris; Maximov, Alexander; Lebedev, Igor; Griban, Andrey

    2010-05-01

    The Klyuchevskaya Group (KG) of volcanoes has the highest magma production rate across the Kamchatka arc and in fact for any arc worldwide. However, modern geochemical studies of Kamen volcano, which is located between Klyuchevskoy, Bezymianny and Ploskie Sopky volcanoes, were not carried out and its relation and petrogenesis in comparison to other KG volcanoes is unknown. Space-time proximity of KG volcanoes and the common zone of seismicity below them may suggest a common source and genetic relationship. However, the lavas of neighboring volcanoes are rather different: high-Mg and high-Al basalts occur at Klyuchevskoy volcano, Hbl-bearing andesites and dаcites dominate at Bezymianny and medium-high-K subalkaline rocks at Ploskie Sopky volcano. Moreover, previously it was shown that distinct fluid signatures were observed in different KG volcanoes. In this report we present geological, petrographical, mineralogical and petrochemical data on the rocks of Kamen volcano in comparison with other KG volcanoes. Three consecutive periods of volcano activity were recognized in geological history of Kamen volcano: stratovolcano formation, development of a dike complex and formation of numerous cinder and cinder-lava monogenetic cones. The rock series of volcano are divided into four groups: olivine-bearing (Ol-2Px and Ol-Cpx), olivine-free (2Px-Pl, Cpx-Pl and abundant Pl), Hb-bearing and subaphyric rocks. While olivine-bearing rocks are observed in all volcanic stages, olivine-free lavas are presented only in the stratovolcano edifice. Lavas of the monogenetic cones are presented by olivine-bearing and subaphyric rocks. Dikes are olivine-bearing and hornblende-bearing rocks. Olivines of the Kamen stratovolcano and dikes vary from Fo60 to Fo83, clinopyroxenes are augites in composition and plagioclases have a bimodal distribution with maximum modes at An50 and An86. Oxides are represented by high-Al spinel, magnetite and titaniferous magnetite. Mineral compositions of the

  14. The EarthChem Deep Lithosphere Dataset: Digital Access to Mantle Xenolith Petrological Data

    Science.gov (United States)

    Block, K. A.; Lehnert, K. A.; Walker, J. D.; Fishman, A.; McDonough, W. F.

    2006-12-01

    Establishment of a geologic framework for the USArray mission of EarthScope largely depends on community efforts that facilitate the integration of seismic data with petrologic, gravity, structural, and other geologic data. The EarthChem federation of interoperable databases (www.earthchem.org) provides cyberinfrastructure in which large geochemical data collections are assembled and curated to maximize data usability and accessibility. In an effort to address the needs of the GeoFrame/USArray community, EarthChem is developing the Deep Lithosphere Petrological Dataset to provide easy access to an integrated, comprehensive, global set of petrological data from upper mantle and lower crustal rocks. The initial focus for EarthChem's Deep Lithosphere dataset is xenolith data from geographic locations identified by GeoFrame as relevant to the USArray mission. Data are compiled in a relational database that complements the data collections of NAVDAT, GEOROC, and PetDB, and which together can be accessed and downloaded through the EarthChem Portal. The web interface permits the user to query by sample location, rock type, mineral, inclusion, author, major oxide, trace element and isotopic composition to build customized datasets. Additionally, radiometric age, host rock information, and model data such as pressure and temperature, including information about the geobarometer/geothermometer used by authors in their calculations, are included in the dataset to provide the perspective of geochemical modeling on the nature of the sub-continental mantle and lower crust for correlation with seismic imaging and geodynamic modeling.

  15. The Middle East.

    Science.gov (United States)

    Blouin, Virginia; And Others

    This sixth grade resource unit focuses on Middle East culture as seen through five areas of the social sciences: anthropology-sociology, geography, history, economics, and political science. Among objectives that the student is expected to achieve are the following: 1) given general information on the Middle East through the use of film, visuals,…

  16. Middle East Respiratory Syndrome

    Centers for Disease Control (CDC) Podcasts

    2014-07-07

    This podcast discusses Middle East Respiratory Syndrome, or MERS, a viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus—MERS-CoV.  Created: 7/7/2014 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 7/7/2014.

  17. Recovery in the East

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    As robust as the economic recovery in East Asia has been in recent months,attention must now be turned to managing emerging risks challenging macroeconomic stability,said World Bank’s latest East Asia and Pacific Economic Update released on October 19.Edited excerpts follow

  18. Petrology and oxygen isotope compositions of chondrules in E3 chondrites

    Science.gov (United States)

    Weisberg, Michael K.; Ebel, Denton S.; Connolly, Harold C.; Kita, Noriko T.; Ushikubo, Takayuki

    2011-11-01

    chondrules, and chondrule recycling. Olivine, possibly a relict grain, in one chondrule has an R chondrite-like oxygen isotope composition and may indicate limited mixing of materials from other reservoirs. Calcium-aluminum-rich inclusions (CAIs) in E3 chondrites have petrologic characteristics and oxygen isotope ratios similar to those in other chondrite groups. However, chondrules from E3 chondrites differ markedly from those in other chondrite groups. From this we conclude that chondrule formation was a local event but CAIs may have all formed in one distinct place and time and were later redistributed to the various chondrule-forming and parent body accretion regions. This also implies that transport mechanisms were less active at the time of and following chondrule formation.

  19. Valanginian ammonites in East Greenland

    DEFF Research Database (Denmark)

    Alsen, Peter

    2001-01-01

    ammonites, Boreal, Tethys, bed-by-bed collection, Valanginian, Wollaston Forland, East Greenland......ammonites, Boreal, Tethys, bed-by-bed collection, Valanginian, Wollaston Forland, East Greenland...

  20. Petrology of blueschist facies metamorphic rocks of the Meliata Unit

    Directory of Open Access Journals (Sweden)

    Faryad Shah Wali

    1997-06-01

    Full Text Available Meliata blueschists originated from basalts, limestones, pelites, psammitic and amphibolite facies basement rocks. Compositionally, the metabasalts have a geochemical signature mostly indicative of a transitional arc-MORB origin, but some mafic rocks having affinity with within plate basalts also present. The mafic blueschists consist of blue amphibole, epidote and albite, rarely also garnet, Na-pyroxene and chloritoid. Apart from phengite and quartz the metapelites and metapsammites contain one or more of the minerals: chloritoid, paragonite, glaucophane, albite, chlorite, occasionally also Na-pyroxene and garnet. Amphibolite facies rocks contain relic garnet, plagioclase and hornblende, the latter two replaced by albite and blue amphibole, respectively. The zoning patterns of blue amphibole, garnet and chloritoid suggest their formation during prograde stage of metamorphism. P-T conditions of meta-morphism are estimated to be about 350-460 oC and 10-12 kbar.

  1. Fluxus East / Petra Stegmann

    Index Scriptorium Estoniae

    Stegmann, Petra

    2008-01-01

    Näitusest "Fluxus East" Kumu Kunstimuuseumis. Fluxuse liikumisest leedu kunstniku George Maciunase (1931-1978) eestvedamisel. Liikumise ilmingutest Eestis (happeningid, muusikaaktsioonid, visuaalne poeesia, mail art). Kuraator Petra Stegmann, kujundaja Andrea Pichl

  2. East- African Medical Journal

    African Journals Online (AJOL)

    East African Medical Journal Vol 83 No. 8 August 2006 ... urology, ENT and orthopaedic groups and these ... no significant difference in orthopaedic patients mortality' with standard; we .... applying TRISS analysis to pediatric blunt trauma.

  3. EAST AFRICAN MEDICAL JOURNAL

    African Journals Online (AJOL)

    2001-12-01

    Dec 1, 2001 ... DIETARY PATTERNS AND DENTAL CARIES IN NURSERY SCHOOL CHILDREN IN NAIROBI ..... bottle act as a bacterial substrate and especially when the ... children for their co-operation, Colgate Palmolive (East Africa) for.

  4. Mineralogy and Petrology of Comet Wild 2 Nucleus Samples

    Energy Technology Data Exchange (ETDEWEB)

    Zolensky, M E; Zega, T J; Yano, H; Wirick, S; Westphal, A J; Weisberg, M K; Weber, I; Warren, J L; Velbel, M A; Tsuchiyama, A; Tsou, P; Toppani, A; Tomioka, N; Tomeoka, K; Teslich, N; Taheri, M; Susini, J; Stroud, R; Stephan, T; Stadermann, F J; Snead, C J; Simon, S B; Siminovici, A; See, T H; Robert, F; Rietmeijer, F M; Rao, W; Perronnet, M C; Papanastassiou, D A; Okudaira, K; Ohsumi, K; Ohnishi, I; Nakanura-Messenger, K; Nakamura, T; Mostefaoui, S; Mikouchi, T; Meibom, A; Matrajt, G; Marcus, M A; Leroux, H; Lemelle, L; Le, L; Lanzirotti, A; Langenhorst, F; Krot, A N; Keller, L P; Kearsley, A T; Joswiak, D; Jacob, D; Ishii, H; Harvey, R; Hagiya, K; Grossman, L; Graham, G A; Gounelle, M; Gillet, P; Genge, M J; Flynn, G; Ferrior, T; Fallon, S; Ebel, D S; Dai, Z R; Cordier, P; Chi, M; Butterworth, A L; Brownlee, D E; Bridges, J C; Brennan, S; Brearley, A; Bradley, J P; Bleuet, P; Bland, P A; Bastien, R

    2006-10-11

    The bulk of the Wild 2 samples appear to be weakly-constructed mixtures of nanometerscale grains with occasional much larger (>1{micro}m) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in Wild 2 require a wide range of formation conditions, probably reflecting different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and absence of hydrous phases indicate that Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require large-scale radial transport in the early protoplanetary disk. The nature of cometary solids is of fundamental importance to our understanding of the early solar nebula and protoplanetary history. Until now we have had to study comets from afar using spectroscopy, or settle for analyses of interplanetary dust particles (IDPs) of uncertain provenance. We report here mineralogical and petrographic analyses of particles derived directly from Comet Wild 2. All of the Wild 2 particles we have thus far examined have been modified in various ways by the capture process. All particles that may have been loose aggregates, ''traveling sand piles'', disaggregated into individual components with the larger, denser components penetrating more deeply into the aerogel. Individual grains experienced a wide range of heating effects that range from excellent preservation to melting (Fig. 1); such behavior was expected (1, 2 ,3). What is remarkable is the extreme variability of these modifications and the fact that severely modified and unmodified materials can be found within a micrometer of each other, requiring tremendous local temperature gradients. Fortunately, we have an internal gauge of impact collection heating. Fe-Ni sulfides are ubiquitous in the Wild 2 samples, are very

  5. Geochemistry and petrology of nephrite from Alamas, Xinjiang, NW China

    Science.gov (United States)

    Liu, Yan; Deng, Jun; Shi, Guanghai; Yui, Tzen-Fu; Zhang, Guibin; Abuduwayiti, Maituohuti; Yang, Liqiang; Sun, Xiang

    2011-08-01

    The Hetian nephrite deposit is one of the largest nephrite deposits worldwide. Located within the Hetian deposit, Xinjiang, Northwest China, the Alamas ore body occurs as veins on the contact between the Late Variscan granodiorite and Precambrian dolomitic marble. Petrographic studies and electronic microprobe analyses reveal two possible nephrite formation processes: (1) dolomitic marble → tremolite and (2) dolomitic marble → diopside → tremolite. Nephrite veins show continuous coloration zones, ranging from white and white-green zones to a green zone towards the granodiorite, with increasing concentrations of Cr, FeO and TFe 2O 3. All these nephrite samples have quite low Cr and Ni contents (8.95-178.7 ppm and 0.05-3.95 ppm, respectively) relative to serpentinite-related nephrite (Cr 2O 3, 0.07-0.43 wt.%; NiO, 0.08-0.36 wt.%). Their bulk-rock REE patterns exhibit strong negative Eu anomalies (0.03-0.21) with declined LREE, flat HREE and low ΣREE concentration (2.84-84.81 ppm), similar to those of host dolomitic marble samples with negative Eu anomalies (0.15-0.23), declined LREE, flat HREE and lower ΣREE concentration (8.48-11.1 ppm), indicating a close genetic relationship between them. Homogenization temperatures analyses on the fluid inclusions in tremolite yield a minimum temperature 293 °C for the nephrite formation. Nephrites have oxygen and hydrogen isotope compositions in the range from +3.2 to +6.2 per mil and -83.0 to -94.7 per mil, respectively. The corresponding equilibrated fluids have isotope compositions of δ 18O = +3.1 to +6.1 (293 °C). Combined with field observation, there are at least three possible fluid sources: meteoric water, magmatic water and CO 2 derived from decarbonation of dolomite, and a metasomatic and dolomite-related origin is suggested for the Alamas ore body in the Hetian nephrite deposit, Xinjiang, NW China.

  6. Petrological cannibalism: the chemical and textural consequences of incremental magma body growth

    Science.gov (United States)

    Cashman, Kathy; Blundy, Jon

    2013-09-01

    The textures of minerals in volcanic and plutonic rocks testify to a complexity of processes in their formation that is at odds with simple geochemical models of igneous differentiation. Zoning in plagioclase feldspar is a case in point. Very slow diffusion of the major components in plagioclase means that textural evidence for complex magmatic evolution is preserved, almost without modification. Consequently, plagioclase affords considerable insight into the processes by which magmas accumulate in the crust prior to their eventual eruption or solidification. Here, we use the example of the 1980-1986 eruptions of Mount St. Helens to explore the causes of textural complexity in plagioclase and associated trapped melt inclusions. Textures of individual crystals are consistent with multiple heating and cooling events; changes in total pressure ( P) or volatile pressure () are less easy to assess from textures alone. We show that by allying textural and chemical analyses of plagioclase and melt inclusions, including volatiles (H2O, CO2) and slow-diffusing trace elements (Sr, Ba), to published experimental studies of Mount St. Helens magmas, it is possible to disambiguate the roles of pressure and temperature to reconstruct magmatic evolutionary pathways through temperature-pressure-melt fraction ( T-- F) space. Our modeled crystals indicate that (1) crystallization starts at > 300 MPa, consistent with prior estimates from melt inclusion volatile contents, (2) crystal cores grow at = 200-280 MPa at F = 0.65-0.7, (3) crystals are transferred to = 100-130 MPa (often accompanied by 10-20 °C of heating), where they grow albitic rims of varying thicknesses, and (4) the last stage of crystallization occurs after minor heating at ~ 100 MPa to produce characteristic rim compositions of An50. We hypothesize that modeled decreases in excess of ~50 MPa most likely represent upward transport through the magmatic system. Small variations in modeled , in contrast, can be effected by

  7. Sphene-centered ocellar texture as a petrological tool to unveil the mechanism facilitating magma mixing

    Science.gov (United States)

    Gogoi, Bibhuti; Saikia, Ashima; Ahmad, Mansoor

    2015-04-01

    The sphene-centered ocellar texture is a unique magma mixing feature characterized by leucocratic ocelli of sphene enclosed in a biotite/hornblende-rich matrix (Hibbard, 1991). The ocelli usually consist of plagioclase, K-feldspar and quartz with sphene crystals at its centre. Although geochemical and isotopic data provide concrete evidence for the interaction between two compositionally distinct magmas, the exact processes by which mixing takes place is yet uncertain. So, textural analysis can be used to decipher the behaviour of two disparate magmas during mixing. Presented work is being carried out on the sphene ocelli, occurring in hybrid rocks of the Nimchak Granite Pluton (NGP), to understand its formation while two compositionally different magmas come in contact and try to equilibrate. The NGP is ca. 1 km2in extent which has been extensively intruded by number of mafic dykes exhibiting well preserved magma mixing and mingling structures and textures in the Bathani Volcano-Sedimentary Sequence (BVSS) located on the northern fringe of the Proterozoic Chotanagpur Granite Gneiss Complex (CGGC) of eastern Indian Shield. From petrographic and mineral chemical studies we infer that when basaltic magma intruded the crystallizing granite magma chamber, initially the two compositionally different magmas existed as separate entities. The first interaction that took place between the two phases is diffusion of heat from the relatively hotter mafic magma to the colder felsic one followed by diffusion of elemental components like K and incompatible elements from the felsic to the mafic domain. Once thermal equilibrium was attained between the mafic and felsic melts, the rheological contrasts between the two phases were greatly reduced. This allowed the felsic magma to back-vein into the mafic magma. The influx of back-veined felsic melt into the mafic system disrupted the equilibrium conditions in the mafic domain wherein minerals like amphibole, plagioclase and biotite

  8. Total exhumation across the Beichuan fault in the Longmen Shan (eastern Tibetan plateau, China): Constraints from petrology and thermobarometry

    Science.gov (United States)

    Airaghi, Laura; de Sigoyer, Julia; Lanari, Pierre; Guillot, Stéphane; Vidal, Olivier; Monié, Patrick; Sautter, Benjamin; Tan, Xibin

    2017-06-01

    The deep structure and deformation mechanisms of the Longmen Shan thrust belt (Sichuan, China), at the eastern border of the Tibetan plateau, were largely debated after the devastating Mw 7.9 Wenchuan earthquake (2008). Recent geophysical studies and field investigations have been focused on the active motion of the major Beichuan fault, which ruptured during the earthquake. However, the total exhumation across the fault still remains unclear. In the hanging wall of the Beichuan fault, the South China block is exhumed in the Pengguan massif. Close to the Beichuan fault, the rocks of the Pengguan massif underwent greenschist facies metamorphism associated with brittle-ductile deformation. No metamorphism is observed in the footwall of the fault. In this study, we characterize and date the metamorphic history recorded in the hanging wall of the Beichuan fault in order to constrain the depth and timing of exhumation of the rocks of the Pengguan massif along the fault. A high-resolution petrological approach involving chemical analyses and X-ray maps was used to analyze the micrometric metamorphic minerals. The P-T conditions of the greenschist facies metamorphic event were estimated by an inverse multi-equilibrium thermodynamic approach. The results, 280 ± 30 °C and 7 ± 1 kbar, suggest that the rocks of the Pengguan massif were exhumed from ca. 20 km depth. Our results underline the importance of the thrusting component in the long-term behavior of the Beichuan fault and provide a minimal depth at which the fault is rooted. In situ laser ablation 40Ar/39Ar dating of metamorphic white mica revealed that the greenschist overprint occurred at 135-140 Ma. The Pengguan massif was therefore partially thrusted along the Beichuan fault during the Lower Cretaceous, long before the Eocene-Miocene exhumation phase which is well-constrained by low-temperature thermochronology. Our results provide the first independent depth information for the exhumation history of the

  9. Petrology of Igneous Clasts in Regolithic Howardite EET 87503

    Science.gov (United States)

    Hodges, Z. V.; Mittlefehldt, D. W.

    2017-01-01

    The howardite, eucrite and diogenite (HED) clan of meteorites is widely considered to originate from asteroid 4 Vesta, as a result of a global magma ocean style of differentiation. A global magmatic stage would allow silicate material to be well mixed, destroying any initial heterogeneity that may have been present resulting in the uniformity of eucrite and diogenite delta(exp 17)O, for example. The Fe/Mn ratio of mafic phases in planetary basalts can be diagnostic of different source bodies as this ratio is little-affected by igneous processes, so long as the oxygen and sulphur fugacities are buffered. Here, pyroxene Fe/Mn ratios in mafic clasts in howardite EET 87503 have been determined to further evaluate whether the HED parent asteroid is uniform. Uniformity would suggest that the parent asteroid was subject to homogenization prior to the formation of HED lithologies, likely through an extensive melting phase. Whereas, distinct differences may point towards heterogeneity of the parent body.

  10. Metastability of Subducted Slabs in the Mantle Transition Zone: A Collaborative Geodynamic, Petrologic, and Seismological Approach

    Science.gov (United States)

    Garber, J. M.; Billen, M. I.; Duncan, M. S.; Roy, C.; Ibourichene, A. S.; Olugboji, T.; Celine, C.; Rodríguez-González, J.; Grand, S. P.; Madrigal, P.; Sandiford, D.; Valencia-Cardona, J. J.

    2016-12-01

    Subducted slabs exhibit a range of geometries in the mantle transition zone. Studies of this phenomenon suggest that olivine and/or pyroxene metastability may profoundly alter the slab density profile, leading to slab flattening (e.g., King et al., 2015) and potentially yielding a resolvable seismological signature (e.g., Kawakatsu and Yoshioka, 2011; Yoshioka et al., 2015). Such metastability may also be critical for deep earthquake generation. Geodynamic modelling of this process is typically done with a simplified petrologic model of the downgoing slab, whereas petrologic studies of phase assemblages in subducted slabs typically impose an idealized geodynamic model with an unrealistic thermal structure. Connecting these two approaches should lead to a better understanding of the consequences of metastable assemblages on subducting slabs. Here, we present a new methodology that combines geodynamic, seismic and petrologic approaches to assess the impact of mineral metastability on dynamic subduction models, developed in a collaborative effort begun at the 2016 NSF CIDER summer program in Santa Barbara, CA. We use two parallel approaches to extrapolate equilibrium rock properties to metastable regions and impose these data on extracted time-slices from robust thermo-mechanical geodynamic models, allowing us to quantify the density and buoyancy changes in the slab that result from considering metastable phase assemblages. Our preliminary results suggest that metastable assemblages can yield a 10-30% density decrease over the subducted slab relative to an equilibrium reference model. We then generate a seismic velocity profile of the slab, and compute waveforms based on the 2D finite-difference method (e.g., Vidale & Helmberger, 1987) to determine whether metastable phases could reasonably be detected by different seismic approaches. Continuing analyses will be aimed at coupling the evolution of geodynamic models with phase metastability to model the feedback between

  11. Reconciling mantle attenuation-temperature relationships from seismology, petrology, and laboratory measurements

    Science.gov (United States)

    Abers, G. A.; Fischer, K. M.; Hirth, G.; Wiens, D. A.; Plank, T.; Holtzman, B. K.; McCarthy, C.; Gazel, E.

    2014-09-01

    attenuation measurements provide a powerful tool for sampling mantle properties. Laboratory experiments provide calibrations at seismic frequencies and mantle temperatures for dry melt-free rocks, but require ˜102-103 extrapolations in grain size to mantle conditions; also, the effects of water and melt are not well understood. At the same time, body wave attenuation measured from dense broadband arrays provides reliable estimates of shear wave attenuation (QS-1), affording an opportunity for calibration. We reanalyze seismic data sets that sample arc and back-arc mantle in Central America, the Marianas, and the Lau Basin, confirming very high attenuation (QS ˜ 25-80) at 1 Hz and depths of 50-100 km. At each of these sites, independent petrological studies constrain the temperature and water content where basaltic magmas last equilibrated with the mantle, 1300-1450°C. The QS measurements correlate inversely with the petrologically inferred temperatures, as expected. However, dry attenuation models predict QS too high by a factor of 1.5-5. Modifying models to include effects of H2O and rheology-dependent grain size shows that the effects of water-enhanced dissipation and water-enhanced grain growth nearly cancel, so H2O effects are modest. Therefore, high H2O in the arc source region cannot explain the low QS, nor in the back arc where lavas show modest water content. Most likely, the high attenuation reflects the presence of melt, and some models of melt effects come close to reproducing observations. Overall, body wave QS can be reconciled with petrologic and laboratory inferences of mantle conditions if melt has a strong influence beneath arcs and back arcs.

  12. Possible petrological controls on the location and time scale of slow slip in SW Japan

    Science.gov (United States)

    Wallis, S.; Mizukami, T.; Yokoyama, H.; Hiramatsu, Y.; Arai, S.; Kawahara, H.; Nagaya, T.

    2014-12-01

    To examine the possibility that there was a petrological control on the location and nature of episodic tremor and slip (ETS), we compared the petrological characteristics of wedge mantle material to the results of recent geophysical observations in the Shikoku area, southwest Japan. This study revealed a close relationship between predicted mineral assemblages in the mantle wedge and the characteristics of slow slip behaviour recorded in the Shikoku area: Short-term ETSs take place in the antigorite +olivine stability field and silent long-term slow slip events (SSEs) take place in the antigorite+brucite stability field. The petrology of the mantle wedge may be an important control on the fluid pressure along the subduction interface and influence the time scales of SSEs. The Cretaceous Sanbagawa oceanic subduction complex of SW Japan preserves fragments of the former mantle wedge in contact with subducted slab units. P-T paths and peak P-T conditions show this belt formed as the result of subduction of a young slab under relatively warm conditions. These characteristics make the Sanbagawa belt a good analogue to modern warm subduction zones such as the Philippine Sea subduction zone beneath SW Japan and offer the possibility of directly examining the former plate boundary. Mantle wedge units derived from shallow depths show evidence for widely developed primary brucite and antigorite. In contrast, units derived from greater depths and higher peak temeratures consist dominantly of antigorite and olivine. Observations of the natural serpentinites suggest that the shallow serpentinite with brucite shows higher absorbency of water and provides fluid pathways that can reduce the fluid pore pressure on the subduction boundary.

  13. Modeling of petrological and geophysical rock parameters in the Central Eastern Alps

    Science.gov (United States)

    Wind, Sandra; Bousquet, Romain; Götze, Hans-Jürgen; Schmidt, Sabine

    2017-04-01

    Intensely studied regions as the Alps allow interdisciplinary approaches for better understanding complex structure of the lithosphere in orogens. For this reason a geophysical 3D-density model of the Eastern Alps has been reworked from the petrological perspective. By modeling the metamorphic density of rocks using the Theriak-Domino software package the influence of temperature, pressure and chemical composition on the density has been analysed. Density-isopleth-plots of orthogneisses, metabasites, ultramafics and metapelites, which are typical rocks of the Tauern Window, have been calculated showing characteristic density trends for each rock type, depending on stable mineralogical phases and changes of reactions influenced by the chemical composition. To further investigation the influence of the chemical composition on rock densities various Zentralgneiss samples were analysed. Chemical compositions of 45 Zentralgneiss samples from literature were used in addition to five reworked and newly measured samples. By the usage of the corresponding thin sections, information on the metamorphic grade, weathering state and water content were gained. For the used temperature and pressure conditions a complex relation between the density and composition was observed, depending mainly on an increasing iron content. Based on the petrological findings a geophysical density model has been reinvestigated using the IGMAS+ software. With respect to the results of the TRANSALP working group and information about the Moho depth, a good correlation between the measured and modeled gravity field was reached in the new petrological 3D-density model. This model has been used to further analyse the impact of the Zentralgneiss unit on the short waves of the modeled gravity field, resulting in a shifting to a lower gravity anomaly of -15 % and +8 % for the calculated maximum and minimum density. In this study we emphasize the importance of multidisciplinary approaches to enable good

  14. Effect of pressure on closure temperature of a trace element in cooling petrological systems

    Science.gov (United States)

    Liang, Yan

    2017-03-01

    Closure temperature is important to many diffusion-related problems involving cooling. The classic model of Dodson and its modifications for cooling petrological systems are formulated at constant pressure. Many petrologic processes involve changes in both temperature and pressure. The effect of changing pressure on diffusional loss in cooling petrological systems has not been considered in Dodson's model. During upwelling, the decompression rate is related to the cooling rate through the slope of the upwelling path. Simple analytical expressions for the average or mean closure temperature and closure pressure in cooling-upwelling mono-mineralic and bi-mineralic systems are obtained by noting that both temperature and pressure decrease as a function of time along the upwelling path. These pressure-adjusted equations are nearly identical to closure temperature equations for isobaric cases if one replaces the activation energy and pre-exponential factor for diffusion in the isobaric formulations by the path-dependent activation energy and pre-exponential factor. The latter also depend on the slope of the upwelling path. The competing effects between pressure and temperature on diffusion during upwelling result in reductions in the effective activation enthalpy for diffusion and exchange enthalpy for partitioning, which in turn leads to systematic deviations in closure temperatures from cases of constant pressure. For systems with large activation volume for diffusion, it may be possible to deduce upwelling path and upwelling rate from closure temperatures and closure pressures of selected elements. Examples of closure temperature and closure pressure for REE diffusion in garnet and clinopyroxene and in garnet-clinopyroxene aggregates are presented and discussed in the context of the minor's rule and the REE-in-garnet-clinopyroxene thermobarometer. Closure temperatures for middle-to-heavy REE in garnet-clinopyroxene aggregates are controlled primarily by diffusion in

  15. Distribution of terrestrial age and petrologic type of meteorites from western Libya

    Energy Technology Data Exchange (ETDEWEB)

    Jull, A.J.T.; Donahue, D.J. (Univ. of Arizona, Tucson (USA)); Wlotzka, F.; Palme, H. (Max-Planck-Institut fuer Chemie, Mainz (West Germany))

    1990-10-01

    A group of 54 meteorites have been recovered from Daraj, Western Libya. After assessment of pairing of samples, using petrologic criteria, {sup 14}C terrestrial ages were obtained on 13 samples selected from 9 different fall events. Eleven of the ages range from 3,500 to 7,600 years, with only two samples having ages in excess of 10,000 years. The cut-off in ages may be related to the timing of climatic changes in the Hammadah al Hamra.

  16. Petrology of Panandhro Lignite deposit, Gujarat in relation to palaeodepositional condition

    Energy Technology Data Exchange (ETDEWEB)

    Singh, A.; Singh, B.D. [Birbal Sahni Institute for Paleobotany, Lucknow (India)

    2005-09-01

    Petrological investigations on Early Eocene lignite from two mine sections of Block-1 in Panandhro Lignite field, under both normal incident (white) and fluorescence (blue light excitation) modes, reveal that deposit is rich in maceral huminite content with sub-ordinate amount of liptinite and low inertinite contents. The maceral composition indicates that sub-bituminous C lignites in both the mine sections are more or less similar with minor differences. Gelification and Tissue Preservation Indices suggest the deposition of lignite in lower delta plain environment in lagoonal conditions.

  17. Petrologic testament to changes in shallow magma storage and transport during 30+ years of recharge and eruption at Kīlauea Volcano, Hawai‘i: Chapter 8

    Science.gov (United States)

    Thornber, Carl R.; Orr, Tim R.; Heliker, Christina; Hoblitt, Richard P.; Carey, Rebecca; Cayol, Valerie; Poland, Michael; Weis, Dominique

    2015-01-01

    Petrologic monitoring of Kīlauea Volcano from January 1983 to October 2013 has yielded an extensive record of glass, phenocryst, melt inclusion, and bulk-lava chemistry from well-quenched lava. When correlated with 30+ years of geophysical and geologic monitoring, petrologic details testify to physical maturation of summit-to-rift magma plumbing associated with sporadic intrusion and prolonged magmatic overpressurization. Changes through time in bulk-lava major- and trace-element compositions, along with glass thermometry, record shifts in the dynamic balance of fractionation, mixing, and assimilation processes inherent to magma storage and transport during near-continuous recharge and eruption. Phenocryst composition, morphology, and texture, along with the sulfur content of melt inclusions, constrain coupled changes in eruption behavior and geochemistry to processes occurring in the shallow magmatic system. For the first 17 years of eruption, magma was steadily tapped from a summit reservoir at 1–4 km depth and circulating between 1180 and 1200°C. Furthermore, magma cooled another 30°C while flowing through the 18 km long rift conduit, before erupting olivine-spinel-phyric lava at temperatures of 1150–1170°C in a pattern linked with edifice deformation, vent formation, eruptive vigor, and presumably the flux of magma into and out of the summit reservoir. During 2000–2001, a fundamental change in steady state eruption petrology to that of relatively low-temperature, low-MgO, olivine(-spinel)-clinopyroxene-plagioclase-phryic lava points to a physical transformation of the shallow volcano plumbing uprift of the vent. Preeruptive comagmatic mixing between hotter and cooler magma is documented by resorption, overgrowth, and compositional zonation in a mixed population of phenocrysts grown at higher and lower temperatures. Large variations of sulfur (50 to >1000 ppm) in melt inclusions within individual phenocrysts and among phenocrysts in most samples

  18. Maritza East 1 presentation

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, M.; Haillet, J.-M.; Casier, F. [ALSTOM Power (Italy). Enviornmental Control Systems

    2007-07-01

    The paper describes the project to develop a 670 MW gross and 600 MW net lignite-fired power plant, the AES-3C Maritza East 1, to be realised adjacent to the site of the existing Maritza East 1 power plant. The site is 40 kilometres south-east of Stara Zagora and 250 km south-east of Sofia, Bulgaria. The project will be more efficient and have lower emissions of sulphur dioxide per MW of electricity generated than the existing Maritza East 1 facility. The facility will have low NOx emissions, an electrostatic precipitator to control the emissions of particular matter and a flue gas desulfurization system to control emissions of sulphur dioxide. The AES 3-C Maritza East 1 plant meets all emissions criteria as defined by the Bulgarian Government, the EU and all other relevant authorities unlike the plants at Maritza East 2 and 1 which will either have to retrofit abatement technology in the next few years or face the prospect of limited hours operation and eventual closure after 2008. The new facility will have zero discharge of waste water. Condenser cooling will be provided by a natural draught cooling tower fed in part by process waters. This recycling of water for the cooling tower will significantly reduce the amount of water withdrawn from the lake. In addition, cooling tower blowdown and other potential facility discharges will be used within the wet limestone flue gas desulfurization system. ALSTOM has paid careful attention to all the different aspects involved: minimisation of environmental impact for both air, water and soil by applying state of the art technologies in all the different areas of the project and, at the same time, delivering an economically profitable installation. 2 ills.

  19. Quantitative EPMA Compositional Mapping of NWA 2995: Characterization, and Petrologic Interpretation of Mafic Clasts

    Science.gov (United States)

    Carpenter, P. K.; Hahn, T. M.; Korotev, R. L.; Ziegler, R. A.; Jolliff, B. L.

    2017-01-01

    We present the first fully quantitative compositional maps of lunar meteorite NWA 2995 using electron microprobe stage mapping, and compare selected clast mineralogy and chemistry. NWA 2995 is a feldspathic fragmental breccia containing numerous highland fine grained lithologies, including anorthosite, norite, olivine basalt, subophitic basalt, gabbro, KREEP-like basalt, granulitic and glassy impact melts, coarse-grained mineral fragments, Fe-Ni metal, and glassy matrix [1]. Chips of NWA 2995, representing these diverse materials, were analyzed by INAA and fused-bead electron-probe microanalysis (EPMA); comparison of analytical data suggests grouping of lunar meteorites NWA 2995, 2996, 3190, 4503, 5151, and 5152. The mean composition of NWA 2995 corresponds to a 2:1 mixture of feldspathic and mare material, with approximately 5% KREEP component [2]. Clast mineral chemistry and petrologic interpretation of paired stone NWA 2996 has been reported by Mercer et al. [3], and Gross et al. [4]. This study combines advances in quantitative EPMA compositional mapping and data analysis, as applied to selected mafic clasts in a polished section of NWA 2995, to investigate the origin of mafic lithic components and to demonstrate a procedural framework for petrologic analysis.

  20. Towards Calibrating the Vestan Regolith: Correlating the Petrology, Chemistry and Spectroscopy of Howardites

    Science.gov (United States)

    Mittlefehldt, D. W.; Ammannito, E.; Hiroi, T.; De Angelis, S.; Di Iorio, T.; Pieters, C. M.; De Sanctis, C.

    2013-01-01

    The Dawn spacecraft carries a visible and infrared mapping spectrometer (VIR) [1] that has acquired spectra for the wavelength range 0.25-5.0 µm at various spatial resolutions covering much of the vestan surface [2]. Through comparison of VIR spectra with laboratory spectra of howardite, eucrite and diogenite meteorites, the distribution of more diogenite-rich and more eucrite-rich terranes on Vesta have been mapped [3], but these maps are qualitative in nature. The available laboratory spectra are not well-integrated with detailed sample petrology or composition limiting their utility for lithologic mapping. Importantly, howardites are now recognized to come in two subtypes, regolithic and fragmental [4]. The former are breccias assembled in part from true regolith, while the latter have had much less exposure to the space environment. We are attempting to develop a more quantitative basis for mapping the distribution of lithologic types on Vesta through acquiring laboratory spectra on splits of howardites that have been petrologically and chemically characterized [5]. Noble gas analyses have been done on some allowing identification of those howardites that have been exposed in the true regolith of Vesta [6].

  1. East Greenland Caledonides: stratigraphy, structure and geochronology: Lower Palaeozoic stratigraphy of the East Greenland Caledonides

    Directory of Open Access Journals (Sweden)

    Smith, M. Paul

    2004-12-01

    Full Text Available The Lower Palaeozoic stratigraphy of the East Greenland Caledonides, from the fjord region of North-East Greenland northwards to Kronprins Christian Land, is reviewed and a number of new lithostratigraphical units are proposed. The Slottet Formation (new is a Lower Cambrian quartzite unit, containing Skolithos burrows, that is present in the Målebjerg and Eleonore Sø tectonic windows, in the nunatak region of North-East Greenland. The unit is the source of common and often-reported glacial erratic boulders containing Skolithos that are distributed throughout the fjord region. The Målebjerg Formation (new overlies the Slottet Formation in the tectonic windows, and comprises limestones and dolostones of assumed Cambrian–Ordovician age. The Lower Palaeozoic succession of the fjord region of East Greenland (dominantly limestones and dolostones is formally placed in the Kong Oscar Fjord Group (new. Amendments are proposed for several existing units in the Kronprins Christian Land and Lambert Land areas, where they occur in autochthonous, parautochthonous and allochthonous settings.

  2. Calc-alkaline lavas from the volcanic complex of Santorini, Aegean Sea, Greece : a petrological, geochemical and stratigraphic study

    NARCIS (Netherlands)

    Huijsmans, J.P.P.

    1985-01-01

    This thesis presents the results of a petrological-geochemical- and stratigraphic study of the calc-alkaline lavas from Santorini, Aegean Sea, Greece. The volcanic complex of Santorini consists of seven eruption centres, of which some have been active contemporaneous. The eruption centres in the

  3. Geology, Alteration, Mineralization, Geochemistry and Petrology of intrusive units in the Shah Soltan Ali prospect area (Southwest of Birjand, South Khorasan province

    Directory of Open Access Journals (Sweden)

    Samaneh Nadermezerji

    2017-07-01

    Full Text Available Introduction The Shah Soltan Ali area is located 85 km southwest of Birjand in the South Khorasan province. This area is part of the Tertiary volcanic-plutonic rocks in the east of the Lut block. The Lut block is bounded to the east by the Nehbandan and associated faults, to the north by the Doruneh and related faults (Sabzevar zone, to the south by the Makran arc and Bazman volcanic complex and to the west by the Nayband Fault. The Lut block is the main metallogenic province in the east of Iran (Karimpour et al., 2012, that comprises of numerous porphyry Cu and Cu–Au deposits, low and high sulfidation epithermal Au deposits, iron oxide deposits, base-metal deposits and Cu–Pb–Zn vein-type deposits. The geology of Shah Soltan Ali area is dominated by volcanic rocks, comprised of andesite and basalt, which are intruded by subvolanic units such as monzonite porphyry, monzodiorite porphyry and diorite porphyry. Materials and methods 1. 170 thin sections of the rock samples as well as 25 polished and thin polished sections were prepared for petrography, alteration and mineralization. 2. Twenty five samples were analyzed for Cu, Pb, Zn, Sb, Mo and As elements by the Aqua regia method in the Zarazama laboratory in Tehran, Iran. 3. Nine samples were analyzed for trace elements [including rare earth elements (REEs]. As a result of these analyses, trace elements and REE were determined by inductively coupled plasma mass spectrometry (ICP-MS in the ACME Analytical Laboratories (Vancouver Ltd., Canada. 4. Ten samples were analyzed for major elements by wavelength dispersive X-ray fluorescence spectrometry in the East Amethyst laboratory in Mashhad, Iran. 5. Five samples were analyzed for Firre Assay analysis in the Zarazma Laboratory in Tehran, Iran. 6. The results of XRD analysis were used for 4 samples. Discussion and results Petrographic studies indicate that subvolcanic rocks consist of diorite porphyry, monzonite porphyry and monzodiorite

  4. East Europe Report

    Science.gov (United States)

    2007-11-02

    Plan Progress Report for CEMA Agriculture (Ngok Bin, Petr Ivashov; INTERNATIONALE ZEITSCHRIFT DER LANDWIRTSCHAFT, No 6, 1985) 1 ECONOMY...INTERNATIONAL AFFAIRS CEMA Civil Air Transport Pilot Training School Described (Dmitri Zassorov; VOLKSARMEE, No 47, 1985) 12 CZECHOSLOVAKIA Former...AFFAIRS CURRENT 5-YEAR PLAN PROGRESS REPORT FOR CEMA AGRICULTURE Moscow/East Berlin INTERNATIONALE ZEITSCHRIFT DER LANDWIRTSCHAFT in German No 6, 1985 pp

  5. JPRS Report East Europe.

    Science.gov (United States)

    2007-11-02

    Radio Broadcasts for Baltic, Ukrainian Polonia Begin [TRYBUNA 8 May] .................................... 2 YUGOSLAVIA Reasons for Tudjman’s...for Baltic, Ukrainian Polonia Elena Lagadinova, deputy chairman; Begin Khristina Pepeldzhiyska, deputy chairman; 90P20027A Warsaw TR YBUNA in Polish 8...Commission for [Text] On 7 May, Polish Radio began broadcasting Socioeconomic Development; special programs for Poles [ Polonia ] residing in the East. 2

  6. Middle East Reform Halts

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The chaos in Iraq poses a great threat to the U.S. plan in the Middle East While the fighting between Israel and Lebanon-based Hezbollah becomes fiercer, security in Iraq also keeps deteriorating, making the region a petrol can that may blow up anytime.

  7. JPRS Report, East Europe.

    Science.gov (United States)

    1988-05-02

    10 Su-22/FITTER K and 15 L-29 " Delfin " (NATO desig- nation: MAYA) from CSSR production as photo-recon- naissance aircraft. The 2 transport aircraft...aircraft within the East Bloc as well: Its trainers, the older L-29 " Delfin " (NATO code name MAYA) and the modern L-39 "Albatros," are being used by the

  8. JPRS Report, East Europe.

    Science.gov (United States)

    1990-02-05

    isolationism. Its leadership ignored the maturing thinking and the social movement in the East and in the [Interview with Cestmir Cisar by Jan Kaspar ...away into archives of erization, robotization , prognostics, cybernetics and philosophy like a fossil from an era in which we no other achievements of

  9. The East Pacific Rise

    NARCIS (Netherlands)

    NN,

    1961-01-01

    Evidence gathered by expeditions of the University of California’s Scripps Institution of Oceanography during the International Geophysical Year suggests that the East Pacific Rise is one of the largest physical structures on earth. It runs in a sickle-shaped curve from near New Zealand 8,000 miles

  10. East African institutions

    DEFF Research Database (Denmark)

    Nordby, Johannes Riber; Jacobsen, Katja

    For the past decade security in East Africa has gained focus internationally. However there is a growing ambition among African states to handle such issues by themselves, sometimes through regional institutions. This has been supported by many Western states but potential risks are often forgotten....

  11. The East Pacific Rise

    NARCIS (Netherlands)

    NN,

    1961-01-01

    Evidence gathered by expeditions of the University of California’s Scripps Institution of Oceanography during the International Geophysical Year suggests that the East Pacific Rise is one of the largest physical structures on earth. It runs in a sickle-shaped curve from near New Zealand 8,000 miles

  12. JPRS Report, East Europe.

    Science.gov (United States)

    1987-09-17

    EAST EUROPE CONTENTS POLITICAL ALBANIA Alia’s Views on Links to Masses Stressed ( Guro Zeneli; BASHKIMI, 8 Jul 87) , 1 Party Control Over Army...ALIA’S VIEWS ON LINKS TO MASSES STRESSED Tirana BASHKIMI in Albanian 8 Jul 87 p 2 [Article by Guro Zeneli: "Always with the Rhythm, the Vigor, the Will

  13. SEDIMENTARY PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111628 Bao Hanyong(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China);Han Guangmin Clay Mineral Analysis of the Early Triassic Tempestites,Lower Yangtze Region(Journal of Jilin University,ISSN1671-5888,CN22-1343/P,40(4),2010,p.947-954,5 illus.,1 table,19 refs.,with English abstract)Key words:tempestite deposit,clay minerals,Yangtze Region

  14. SEDIMENTARY PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    20160899 Chen Ji(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China);Jiang Zaixing Sedimentary Facies Characteristics and Palaeoenvironment of Jurassic Yangye Forma-

  15. IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20150781 Bai Daoyuan(Hunan Institute of Geological Survey,Changsha 410016,China);Zhong Xiang Zircon SHRIMP U-Pb Dating and Geochemistry of Caledonian Miao’ershan Pluton in the Western Part of the Nanling Mountains and Their Tectonic Significance(Acta Petrologica et Mineralogica,ISSN1000-6524,CN11-1966/P,33(3),2014,p.407

  16. IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    20160156Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang The Zircon SHRIMP U-Pb Dating,Geochemical Characteristics and Tectonic Setting of Caledonian Yuechengling Pluton in the Western Segment of the Nanling Mountains(Geochimica,ISSN0379-1726,CN44-1398/P,44(1),2015,p.27-42,15illus.,5

  17. IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20150130Chen Di(Hunan Institute of Geological Survey,Changsha 410116,China);Chen Yanming Magma Mixing in the Xitian Pluton of Hunan Province:Evidence from Petrography,Geochemistry and Zircon U-Pb Age(Geology in China,ISSN1000-3657,CN11-1167/P,41(1),2014,p.61-78,14illus.,2tables,69refs.)Key words:biotite granite,monzogranite,U-Pb dating,Hunan Province The Xitian pluton area is located in the middle segment of the Nanling Mountains,

  18. METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091533 Gao Changgui(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Liu Yongsheng Distributions and Geodynamic Implications of High Field Strength Elements in Rutile from Ultrahigh Pressure Eclogites(Earth Science,ISSN1000-2383,CN42-1233/P,33(4),2008,p.487-503,8 illus.,3 tables,80 refs.)Key words:eclogite,Su-Lu orogenic beltsTrace element compositions of rutiles in eclogites from the Chinese Continental Scientific Drilling(CCSD)main hole were analyzed using LA-ICP-MS.The results indicate that Nb and Ta contents of rutiles are significantly controlled by whole rock compositions,while Zr and Hf show no obvious dependence on the whole rock compositions.Coupled with enrichments of Pb and Sr at the rim of the interstitial rutiles,Zr contents decrease from the core to the rim.

  19. IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20090158 Bai Daoyuan (Hunan Institute of Geological Survey, Xiangtan 411100, China); Zhou Liang Genesis and Tectonic Setting of Indosinian Granites in Southeast Hunan Province (Acta Petrologica et Mineralogica, ISSN1000-6524, CN11-1966/P, 26(3), 2007, p.197-212, 8 illus., 3 tables, 77 refs.)

  20. IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20101527 Bai Zhida (China University of Geosciences, Beijing 100083, China); Xu Debin Characteristics and Zircon SHRIMP U-Pb Dating of the Amduo Trachyte, Tibet, China (Geological Bulletin of China, ISSN1671-2552, CN11-4648/P, 28(9), 2009, p.1229-1235, 6 illus., 4 tables, 16 refs.)

  1. IGNEOUS PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20102258 Cheng Shunbo(Yichang Institute of Geology and Mineral Resource,Yichang 443003,China);Fu Jianming Zircon SHRIMP U-Pb Dating and Geochemical Characteristics of Daning Batholith in Northeastern Guangxi(Geology in China,ISSN1000-3657,CN11-1167/P,36(6),2009,p.1278-1288,7 illus.,3 tables,41 refs.,,with English abstract)Key words:granite,SHRIMP dating,Guangxi20102259 Gao Yang(China University of Geosciences,Beijing 100083,China);Zhang Zhaochong Geology-Geochemistry and Petrogenesis of Late Hercynian Granites in Baoshan Area,Heilongjiang Province(Acta Petrologica et Mineralogica,ISSN

  2. METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20090911 Chen Junlu(Xi’an Institute of Geology and Mineral Resources,China Geological Survey,Xi’an 710054,China);Xu Xueyi Geological Features and SHRIMP U-Pb Zircon Age of the Yanwan-Yinggezui Ophiolitic M(?)lange in the Taibai Area,Westren Qinling,China(Geogolical Bulletin of China, ISSN1671-2552,CN11-4648/P,27(4),

  3. METAMORPHIC PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20151583 Cui Jianjun(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing100081,China);Dong Shuwen135~130 Ma:The Timing of Slab Breakoff Again in the Dabie Mountains?(Acta Geoscientica Sinica,ISSN1006-3021,CN11-

  4. Estimated Thickness of the Cotton Valley Group to the Top of the Smackover Formation, Western Gulf and East Texas Basin and Louisiana-Mississippi Salt Basins Provinces (047, 048 and 049)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This isopach map shows the thickness of the interval from the top of the Cotton Valley Group to the top of the Smackover Formation. It was necessary to contour this...

  5. Estimated Thickness of the Travis Peak-Hosston Formations to the Top of the Cotton Valley Group, Western Gulf and East Texas Basin and Louisiana-Mississippi Salt Basins Provinces (047, 048 and 049)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This isopach map shows the thickness of the interval from the top of the Travis Peak or Hosston Formations to the top of the Cotton Valley Group. The map was...

  6. Structure Contour of the Top of the Travis Peak-Hosston Formations, Western Gulf and East Texas Basin and Louisiana-Mississippi Salt Basins Provinces (047, 048 and 049)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map shows the structural configuration of the top of the Travis Peak or Hosston Formations in feet below sea level. The map was produced by calculating the...

  7. Petrologic and Geochemical Characteristics and Origin of Gusui Cherts,Guangdong Province,China

    Institute of Scientific and Technical Information of China (English)

    EDWARDH.CHOWN; EDWARDH.CHOWN; 等

    1994-01-01

    The characteristic structures of the Precambrian cherts from the Gusui section, Guangdong ,Chi-na, include bedded structure ,laminated structure ,massive structure and pseudobrecciated structure.The chert is characterized by consistently low abundance of TiO2,Al2O3 and most trace elements.Howevver ,it is enriched in Ba,As,Sb,Hg and Se.In Al-Fe-Mn ternary diagrams,it falls into the "hydrothermal field" .Correspondence analysis and factor analysis show that many elements show up in the factor that represents the leaching of country rocks by hydrothermal solutions,and are the very characteristic element association fo the geochemically anomalous South China basement.Petrologic and geochemical evidence suggests a hydrothermal origin for the chert.The chert may have been formed in a Precambrian fift or an extension zone developed within the Yunkai marginal geosyncline, with a fault system linking it to an unknown heat source at depth.

  8. Geochemical and petrological sampling and studies at the first moon base

    Science.gov (United States)

    Haskin, L. A.; Korotev, R. L.; Lindstrom, D. J.; Lindstrom, M. M.

    Strategic sampling appropriate to the first-order lunar base can advance a variety of first-order lunar geochemical and petrological problems. Field observation and collection of samples would be done on the lunar surface, but detailed analysis would be done mainly in terrestrial laboratories. Among the most important areas of investigation for which field observations can be made and samples can be collected at the initial base are regolith studies, studies of mare and highlands stratigraphy, and a search for rare materials such as mantle nodules. Since the range of exploration may be limited to a radius of about 20 km from the first lunar base, locating the base near a mare-highlands boundary would enable the greatest latitude in addressing these problems.

  9. Geochemical and petrological sampling and studies at the first moon base

    Science.gov (United States)

    Haskin, L. A.; Korotev, R. L.; Lindstrom, D. J.; Lindstrom, M. M.

    1985-01-01

    Strategic sampling appropriate to the first-order lunar base can advance a variety of first-order lunar geochemical and petrological problems. Field observation and collection of samples would be done on the lunar surface, but detailed analysis would be done mainly in terrestrial laboratories. Among the most important areas of investigation for which field observations can be made and samples can be collected at the initial base are regolith studies, studies of mare and highlands stratigraphy, and a search for rare materials such as mantle nodules. Since the range of exploration may be limited to a radius of about 20 km from the first lunar base, locating the base near a mare-highlands boundary would enable the greatest latitude in addressing these problems.

  10. Tectonic and petrologic evolution of the Western Mediterranean: the double polarity subduction model

    Science.gov (United States)

    Melchiorre, Massimiliano; Vergés, Jaume; Fernàndez, Manel; Torné, Montserrat; Casciello, Emilio

    2016-04-01

    The geochemical composition of the mantle beneath the Mediterranean area is extremely heterogeneous. This feature results in volcanic products whose geochemical features in some cases do not correspond to the geodynamic environment in which they are sampled and that is observed at present day. The subduction-related models that have been developed during the last decades to explain the evolution of the Western Mediterranean are mainly based on geologic and seismologic evidences, as well as petrography and age of exhumation of the metamorphic units that compose the inner parts of the different arcs. Except few cases, most of these models are poorly constrained from a petrologic point of view. Usually the volcanic activity that affected the Mediterranean area since Oligocene has been only used as a corollary, and not as a key constrain. This choice is strictly related to the great geochemical variability of the volcanic products erupted in the Western Mediterranean, due to events of long-term recycling affecting the mantle beneath the Mediterranean since the Variscan Orogeny, together with depletion episodes due to partial melting. We consider an evolutionary scenario for the Western Mediterranean based on a double polarity subduction model according to which two opposite slabs separated by a transform fault of the original Jurassic rift operated beneath the Western and Central Mediterranean. Our aim has been to reconstruct the evolution of the Western Mediterranean since the Oligocene considering the volcanic activity that affected this area since ~30 Ma and supporting the double polarity subduction model with the petrology of the erupted rocks.

  11. The Distant Morphological and Petrological Features of Shock Melt Veins in the Suizhou L6 Condrite

    Energy Technology Data Exchange (ETDEWEB)

    X Xie; Z Sun; M Chen

    2011-12-31

    The morphology and petrology of distinct melt veins in the Suizhou L6 chondrite have been investigated using scanning electron microscopy, electron microprobe analyses, and Raman spectroscopy, synchrotron energy-dispersive diffraction, and transmission electron microscopy. It is found that the melt veins in the Suizhou meteorite morphologically are the simplest, straightest, and thinnest among all shock veins known from meteorites. At first glance, these veins look like fine fractures, but petrologically they are solid melt veins of chondritic composition and consist of fully crystalline materials of two distinct lithological assemblages, with no glassy material remaining. The Suizhou melt veins contain the most abundant high-pressure mineral species when compared with all other veins known in chondrites. Thus, these veins in Suizhou are classified as shock veins. All rock-forming and almost all accessory minerals in the Suizhou shock veins have been transformed to their high-pressure polymorphs, and no fragments of the precursor minerals remain in the veins. Among the 11 high-pressure mineral phases identified in the Suizhou veins, three are new high-pressure minerals, namely, tuite after whitlockite, xieite, and the CF phase after chromite. On the basis of transformation of plagioclase into maskelynite, it is estimated that the Suizhou meteorite experienced shock pressures and shock temperatures up to 22 GPa and 1000 C, respectively. Shearing and friction along shock veins raised the temperature up to 1900-2000 C and the pressure up to 24 GPa within the veins. Hence, phase transition and crystallization of high-pressure minerals took place only in the Suizhou shock veins. Fast cooling of the extremely thin shock veins is regarded as the main reason that up to 11 shock-induced high-pressure mineral phases could be preserved in these veins.

  12. Lateral variation in geochemistry, petrology, and palynology in the Elswick coal bed, Pike County, Kentucky

    Science.gov (United States)

    Hower, J.C.; Ruppert, L.F.; Eble, C.F.

    2007-01-01

    The Middle Pennsylvanian/Langsettian (Westphalian A) Elswick coal bed, correlative to the Upper Banner of Virginia, is a rare example of a mined high-sulfur (> 2%) coal in Eastern Kentucky, a region known for low-sulfur coals. To characterize lateral variation in the geochemistry, petrography, and palynology of the Elswick coal bed, three sites were sampled along a southeast-northwest transect within a single mine. At the southeastern site, the lower 101??cm of the 116-cm thick coal is dull, generally dominated by durain and dull clarain. While all benches at this site fit within the previously-defined "mixed palynoflora - moderate/low vitrinite group," suggesting a stressed environment of deposition, the palynology of the benches of the dull interval show greater diversity than might be expected just from the petrology. Lithology is generally similar between the sites, but each site has some differences in the petrology. Overall, the coal bed shows significant lateral variation in properties at the mine scale, some of which can be attributed to the gain or loss of upper and lower lithologies, either through an actual physical merging or through the change in character of lithotypes. Sulfur content varies between the three sites examined for this study. Site 3, located in the northwestern portion of the study area is characterized by a strikingly high sulfur zone (7.45%) in the middle of the coal bed, a feature missing at the other sites. Pyrite and marcasite, in a mid-seam lithotype at the northwestern site (site 3), show signs of overgrowths, indicating multiple generations of sulfide emplacement. The high-sulfur site 3 lithologies all have massive overgrowths of euhedral and framboidal pyrite, fracture- and cleat-fill pyrite, and sulfide emplacement in fusinite lumens. Sulfur is high throughout the mine area, but variations are evident in the extent of secondary growth of sulfides. ?? 2006 Elsevier B.V. All rights reserved.

  13. On the formation of granulites

    Science.gov (United States)

    Bohlen, S.R.

    1991-01-01

    The tectonic settings for the formation and evolution of regional granulite terranes and the lowermost continental crust can be deduced from pressure-temperature-time (P-T-time) paths and constrained by petrological and geophysical considerations. P-T conditions deduced for regional granulites require transient, average geothermal gradients of greater than 35??C km-1, implying minimum heat flow in excess of 100 mW m-2. Such high heat flow is probably caused by magmatic heating. Tectonic settings wherein such conditions are found include convergent plate margins, continental rifts, hot spots and at the margins of large, deep-seated batholiths. Cooling paths can be constrained by solid-solid and devolatilization equilibria and geophysical modelling. -from Author

  14. Petrology and geochemistry of Late Proterozoic hornblende gabbros from southeast of Fariman, Khorasan Razavi province, Iran

    Directory of Open Access Journals (Sweden)

    Seyed Masoud Homam

    2015-04-01

    Full Text Available Introduction Hornblende-bearing gabbroic rocks are quite common in subduction-related magmatic suites and considered to represent magmatic differentiation process in arc magmas (Heliker, 1995; Hickey-Vargas et al., 1995; Mandal and Ray, 2012. The presence of hornblende as an important mineral phase in gabbroic rocks of subduction zone has been considered either as an early crystallizing mineral from water-bearing mafic magmas (Beard and Borgia 1989; Mandal and Ray, 2012 or as a product of reaction of early crystallized minerals (olivine, pyroxene and plagioclase and water-rich evolved melt/aqueous fluid (Costa et al., 2002; Mandal and Ray, 2012. The careful study of petrology and geochemistry of hornblende-bearing gabbroic rocks from Chahak area, of Neoproterozoic age, can provide important information about their petrogenesis. Because of the special characteristics of Chahak hornblende gabbros according to their age and their situation in the main structural units of Iran, their study can present critical keys for the knowledge of geological history of Iran specially central Iran zone. Material and Methods This study carried out in two parts including field and laboratory works. Sampling and structural studies were carried out during field work. Geological map for the study area was also prepared. 65 thin and polished thin sections for petrographical purpose were studied. Major oxides, rare earth elements and trace elements were analyzed for 4 samples (92P-1, 92P-3, B1and B6 from hornblende gabbros on the basis of 4AB1 method using ICP-MS of ACME Laboratory from Canada. In addition, major oxides of three hornblende gabbro samples (89P-62, 89P-59 and 89P-46 were used from Partovifar (Partovifar, 2012. Results and discussion Fariman metamorphic terrains, of Proterozoic age, consist of metamorphosed sedimentary and igneous (plutonic and volcanic rocks. Hornblende gabbros of the study area include plagioclase, hornblende, biotite pyroxene and

  15. Growing East Asia

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ It was a busy exchanging period of East Asia in recent days. From October 28 to 31, 2007 the fourth China-ASEAN Expo (CAEXPO) and the fourth China-ASEAN Business and Investment Summit (CABIS) were held concurrently in Nanning, capital city of Guangxi Province in China. In the Expo,China witnessed a turnout of over 33,000 trade visitors and over 180 investment cooperation projects with ASEAN.

  16. Near East & South Asia.

    Science.gov (United States)

    2007-11-02

    matriculate them into the Air College as pilot candidates, after they have obtained the general sec- ondary "scientific department" diploma. 52 NEAR EAST...Islamic training, Arabic, mathematics , physics, chemistry, biology, geology, history, geography, computer science, and English. Additional material will...This will help prepare the student for military life. The student will continue to advance gradually through the program until he matriculates as a

  17. Ab initio quantum mechanical investigation of structural and chemical-physical properties of selected minerals for minero-petrological, structural ceramic and biomaterial applications

    OpenAIRE

    Ulian, Gianfranco

    2014-01-01

    The purpose of this thesis is the atomic-scale simulation of the crystal-chemical and physical (phonon, energetic) properties of some strategically important minerals for structural ceramics, biomedical and petrological applications. These properties affect the thermodynamic stability and rule the mineral-environment interface phenomena, with important economical, (bio)technological, petrological and environmental implications. The minerals of interest belong to the family of phyllosilicates ...

  18. 东秦岭丹凤岩群的形成时代和构造属性%A Study of Formation Epoch and Tectonic Attribute of the Danfeng Group Complex in East Qinling Mountains

    Institute of Scientific and Technical Information of China (English)

    裴先治; 李厚民; 李国光

    2001-01-01

    Located on the Shangdan tectonic zone, the Danfeng Group complex in the East Qinling mountains was on whole formed in Newproterozoic (1?000~800Ma). Petrogeochemical characterisitics of metabasic volcanic rocks within the complex of this group show that, instead of being ophiolite, they are island_arc type volcanic rocks formed in an active epicontinental paleoisland_arc tectonic environment under the plate tectonic system of Newproterozoic main orogenic epoch in Qinling orogenic belt.%东秦岭丹凤岩群位于秦岭商丹构造带上,主体形成于新元古代(1000Ma~800Ma),其中变质基性火山岩的岩石地球化学特征表明为岛弧型火山岩系,而非蛇绿岩,其形成于秦岭造山带新元古代主造山期板块构造体制下的活动陆缘古岛弧构造环境.

  19. Magmatism of the troughs behind the New Hebrides island arc (RV Jean Charcot SEAPSO 2 cruise): K-Ar geochronology and petrology

    Science.gov (United States)

    Monjaret, M. C.; Bellon, H.; Maillet, P.

    1991-06-01

    The chronological, petrological and geochemical studies of lavas dredged from the New Hebrides back-arc troughs allow a new interpretation of the origin of these troughs. In every area, volcanism from the troughs precedes that of the adjacent islands. Four main periods of volcanic activity have been defined: 6.5 to 4.8, 4.1 to 2, 2 to 1 and 1 to 0 Ma. The volcanic affinity is generally orogenic. But some variation exists and two geochemical types (Mg-IAT basalts and hyper-K acid lavas) seem to mark the trough structuration. The succession of the different geochemical types reveals a polyphased and diachronous formation of the troughs from south to north on an arc substratum. Only the Vanikoro area (the most northern one) shows basalts with geochemical characteristics intermediate between MORB and island-arc tholeiites and acid lavas near primitive island-arc lavas, which illustrate the initiation of the arc in this area. So, the New Hebrides back-arc troughs must be considered as intra-arc troughs and are back-arc structures only because of their location at the rear of the active emerging arc.

  20. Seismic, petrological and geodynamical constraints on thermal and compositional structure of the upper mantle: global thermochemical models

    DEFF Research Database (Denmark)

    Cammarano, Fabio; Tackley, Paul J.; Boschi, Lapo

    2011-01-01

    Mapping the thermal and compositional structure of the upper mantle requires a combined interpretation of geophysical and petrological observations. Based on current knowledge of material properties, we interpret available global seismic models for temperature assuming end-member compositional...... lateral compositional variations does not change significantly the thermal interpretation of seismic models, but gives a more realistic density structure. Modelling a petrological lithosphere gives cratonic temperatures at 150 km depth that are only 100 K hotter than those obtained assuming pyrolite......, and thus less buoyant, continental lithosphere is required to explain gravity data. None of the seismic tomography models we analyse is able to reproduce accurately the thermal structure of the oceanic lithosphere. All of them showtheir lowest seismic velocities at~100 km depth beneathmid-oceanic ridges...

  1. Magmatism in the Asunción-Sapucai-Villarrica Graben (Eastern Paraguay) Revisited: Petrological, Geophysical, Geochemical, and Geodynamic Inferences

    OpenAIRE

    Piero Comin-Chiaramonti; Angelo De Min; Aldo Cundari; Girardi,Vicente A. V.; Marcia Ernesto; GOMES,CELSO B.; Claudio Riccomini

    2013-01-01

    The Asunción-Sapucai-Villarrica graben (ASV) in Eastern Paraguay at the westernmost part of the Paraná Basin was the site of intense magmatic activity in Mesozoic and Tertiary times. Geological, petrological, mineralogical, and geochemical results indicate that the following magmatic events are dominant in the area: (1) tholeiitic basalt and basaltic andesites, flows and sills of low- and high-titanium types; (2) K-alkaline magmatism, where two suites are distinguished, that is, basanite to p...

  2. Integrated geophysical-petrological modeling of lithosphere-asthenosphere boundary in central Tibet using electromagnetic and seismic data

    OpenAIRE

    Vozar, Jan; Jones, Alan G.; Fullea, Javier; Agius, Matthew R.; LEBEDEV, Sergei; Le Pape, Florian; Wei, Wenbo

    2014-01-01

    We undertake a petrologically driven approach to jointly model magnetotelluric (MT) and seismic surface wave dispersion (SW) data from central Tibet, constrained by topographic height. The approach derives realistic temperature and pressure distributions within the upper mantle and characterizes mineral assemblages of given bulk chemical compositions as well as water content. This allows us to define a bulk geophysical model of the upper mantle based on laboratory and xenolith data for the mo...

  3. Calc-alkaline lavas from the volcanic complex of Santorini, Aegean Sea, Greece : a petrological, geochemical and stratigraphic study

    OpenAIRE

    Huijsmans, J.P.P.

    1985-01-01

    This thesis presents the results of a petrological-geochemical- and stratigraphic study of the calc-alkaline lavas from Santorini, Aegean Sea, Greece. The volcanic complex of Santorini consists of seven eruption centres, of which some have been active contemporaneous. The eruption centres in the northern part of Santorini mainly produced lava flows in contrast with a long-lived eruption centre in the southern part, that mainly produced pyroclastic deposits. The lavas and pyroclastics of Santo...

  4. Drugs in East Germany.

    Science.gov (United States)

    Dressler, J; Müller, E

    1997-09-01

    Germany was divided into two parts after World War II. The closed border and a nonconvertible currency in the Eastern part were the factors that did not allow a drug market to develop. Alcohol and medicaments were used as substitute drugs. Since Germany was reunified 5 years ago, there are now the same conditions prevailing for the procurement and sale of drugs in East Germany as there are in the Western German states. This report describes the current state of drug traffic, especially in Saxony, under the new social conditions.

  5. East Asian welfare regime

    DEFF Research Database (Denmark)

    Abrahamson, Peter

    2017-01-01

    . Political science studies tend to conclude that the region has left the old legacies behind and are now welfare states comparable to European states including them either in the conservative type (e.g. Japan), the liberal type (e.g. Korea) or even as a tendency in the Nordic type (e.g. China), while studies......The paper asks if East Asian welfare regimes are still productivist and Confucian? And, have they developed public care policies? The literature is split on the first question but (mostly) confirmative on the second. Care has to a large, but insufficient extent, been rolled out in the region...

  6. The petrographical and organic geochemical composition of coal from the East field, Bogovina Basin (Serbia)

    Energy Technology Data Exchange (ETDEWEB)

    Zivotic, Dragana [Faculty of Mining and Geology, University of Belgrade, Djusina 7, Belgrade (RS); Jovancicevic, Branimir; Grzetic, Ivan; Stojanovic, Ksenija [Faculty of Chemistry, University of Belgrade, Studentski trg 16, Belgrade (RS); Schwarzbauer, Jan [Institute of Geology and Geochemistry of Petroleum and Coal, Rhenish-Westphalian Technical University of Aachen, Aachen (Germany); Cvetkovic, Olga; Sajnovic, Aleksandra [Centre of Chemistry, IChTM, Studentski trg 16, Belgrade (RS); Ercegovac, Marko [Serbian Academy of Sciences and Arts, Knez Mihailova 35, Belgrade (RS)

    2010-04-01

    A petrological and organic geochemical study was performed on coal samples from the East field deposit, Bogovina Basin, Serbia. Fourteen coal samples were collected from different parts of the Main and Upper coal seams from fresh, working faces in the underground subbituminous coal mine. The Lower Miocene (?) coal of the East field is a typical humic coal with huminite, liptinite and inertinite concentrations of up to 81.4 vol.%, 16.1 vol.% and 13.5 vol.%, respectively. Densinite is the most abundant maceral with variable amounts of ulminite and gelinite. Sporinite and liptodetrinite are the most common macerals of the liptinite group. Exsudatinite was detected in the lower part of the Lower coal seam. Inertodetrinite is the most abundant maceral of the inertinite group. The mineral matter consists mostly of clay minerals and carbonates. The mean random huminite reflectance (ulminite B) for the Main coal seam is 0.42 {+-} 0.04%Rr, and 0.41 {+-} 0.04%Rr for the Upper coal seam, which are typical for an immature to early mature stage of the organic matter. The distribution and abundance of n-alkanes and steranes indicates a significant contribution of epicuticular waxes from higher plants. High amount of phyllocladane-type diterpenoids (16{alpha}(H)-phyllocladane) suggests that coal forming plants were conifer families Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Sciadopityaceae, and Phyllocladaceae, while a higher amount of pimarane and norpimarane suggests Pinaceae, Taxodiaceae, and Cupressaceae. The pristane/phytane (Pr/Ph) ratio implies variable anaerobic to oxic conditions during sedimentation. The distribution of the hopanes detected in the Bogovina East field coal indicates an immature to early mature stage of the organic matter, which is in agreement with huminite reflectance. The high coal sulphur contents from the East field are characteristic for slightly alkaline depositional environments generated by bentonite from the basement of the Main

  7. Petrology of Deep Storage, Ingassing, and Outgassing of Terrestrial Carbon (Invited)

    Science.gov (United States)

    Dasgupta, R.

    2010-12-01

    Fluxes of carbon between the mantle and the exosphere modulate Earth's atmosphere and climate on short to long time scales. Carbon geochemistry of mantle-derived samples suggests that the fluxes associated with deep cycle are in the order of 1012-13 g C/yr and the reservoir sizes involved in deep carbon are in the order of 1022-23 g C. Petrology of deep storage is critical to this long-term evolution and distribution of terrestrial carbon. Here I synthesize the petrologic constraints that are critical in understanding the evolution of deep terrestrial carbon. Carbon is a volatile, trace element in the Earth's mantle. But unlike most other trace elements including hydrogen, which in the Earth’s mantle is held in dominant silicate minerals, carbon is stored in accessory phases. The accessory phase of interest, with increasing depth, changes typically from fluids/melts → calcite/dolomite → magnesite → diamond/ Fe-rich alloy/ Fe-metal carbide, assuming that the mass balance and oxidation state are buffered solely by silicates. If, however, carbon is sufficiently abundant, locally it may overwhelm the mass balance and redox buffer of the Earth’s interior. For example, carbon may reside as carbonate even in the deep mantle, which otherwise is thought to be reduced and not conducive for carbonate stability. If Earth's deep mantle is Fe-metal saturated, carbon storage in metal alloy and as metal carbide is difficult to avoid for depleted and enriched domains, respectively. Carbon ingassing to the interior is aided by modern subduction of the carbonated oceanic lithosphere, whereas outgassing from the mantle is controlled by decompression melting of carbon-bearing mantle. Carbonated melting at >300 km depth or redox melting of diamond-bearing or metal/metal carbide-bearing mantle at somewhat shallower depth generates carbonatitic and carbonated silicate melts, which are the chief agents for liberating carbon from the solid Earth to the exosphere. Petrology allows

  8. Coal petrology and genesis of Jurassic coal in the Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Weihua Ao

    2012-01-01

    Full Text Available Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin, northwestern China. The huge reserves of this high quality coal have a high commercial value. We studied the coal’s petrologic characteristics and its maceral distribution to determine the maceral’s contribution to generation of oil and gas. The results show that the Jurassic coals in the Ordos Basin have special petrological features because of the Basin’s unique depositional environment which was mainly a series of high-stand swamps in the upper fluvial system. These petrographic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers. After burial, the peat continued to undergo oxidizing conditions, this process generated extensive higher inertinite contents in the coals and the vitrinite components were altered to semi-vitrinite. The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal, dull coal, semilustrous and lustrous coal. The proportions of semi-dull coal and dull coal are higher in the basin margins, especially in the area near the northern margin. The numbers of semilustrous and lustrous coals increase southwards and towards the central basin. This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components. Another observation is that in the Ordos’ coal sequences, especially in the lower part, some sandstone beds are thick, up to 20 m with a coarse grain size. The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure. The fusinite structure is clear and well preserved. After burial, the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology. The sand bodies in the roof and floor exhibit good

  9. Petrología y estructura de la faja de deformación La Chilca, Catamarca Petrology and structure of La Chilca Shear Zone, Catamarca

    Directory of Open Access Journals (Sweden)

    Mariano A. Larrovere

    2008-06-01

    Full Text Available Los estudios de campo, petrológicos y estructurales permitieron definir y caracterizar una zona de cizalla dúctil sobre el basamento metamórfico de las Sierras Pampeanas noroccidentales. La faja de deformación La Chilca se extiende en dirección nornoroeste por unos 24 kilómetros de largo y un ancho de 1 a 4 kilómetros sobre el límite austral de la sierra de Aconquija y su prolongación hacia el sur sobre la parte septentrional de la sierra de Ambato. Está compuesta por milonitas, protomilonitas y blastomilonitas que son el producto de la deformación dúctil que afectó al basamento metamórfico conformado originalmente por migmatitas y gneises. Las condiciones metamórficas durante la deformación alcanzaron la facies de esquistos verdes hasta la facies de anfibolita, con temperaturas de entre 350 a 500ºC. La foliación milonítica C predominante posee una orientación general N 330°/42° ENE, plano sobre el cual se desarrollan las lineaciones de estiramiento mineral con una orientación media de N 68°/42°. Determinamos para la esta faja de cizalla movimientos generales de carácter inverso, con desplazamientos del techo hacia el suroeste (N248°. Rasgos locales internos de carácter normal sugieren una mayor complejidad en la cinemática de deformación.Field, petrological and structural studies allowed to define and and to characterize a ductile shear zone on the metamorphic basement of the northwestern Sierras Pampeanas. La Chilca Shear Zone has a NNW trend for about 24 km and a width of 1-4 km in the southern border of the Sierra de Aconquija and northern part of the Sierra de Ambato. It is composed by mylonites, protomylonites and blastomylonites that are the product of the ductile deformation that affected the metamorphic basement originally composed by migmatites and gneisses. The metamorphic conditions during the deformation reached greenschist facies to amphibolite facies, with temperatures around 350 to 500 ºC. The

  10. East African ROAD

    Science.gov (United States)

    Tekle, Kelali

    2016-10-01

    In the developing world astronomy had been treated as the science of elites. As a result of this overwhelming perception, astronomy compared with other applied sciences has got less attention and its role in development has been insignificant. However, the IAU General Assembly decision in 2009 opened new opportunity for countries and professionals to deeply look into Astronomy and its role in development. Then, the subsequent establishment of regional offices in the developing world is helping countries to integrate astronomy with other earth and space based sciences so as to progressively promote its scientific and development importance. Gradually nations have come to know that space is the frontier of tomorrow and the urgency of preeminence on space frontier starts at primary school and ascends to tertiary education. For this to happen, member nations in east African region have placed STEM education at the center of their education system. For instance, Ethiopian has changed University enrollment strategy to be in favor of science and engineering subjects, i.e. every year seventy percent of new University entrants join science and engineering fields while thirty percent social science and humanities. Such bold actions truly promote astronomy to be conceived as gateway to science and technology. To promote the concept of astronomy for development the East African regional office has actually aligned it activities to be in line with the focus areas identified by the IAU strategy (2010 to 2020).

  11. Study on Seam Features and Control Factors of Huagang Formation of Xihu Depression in East Sea%东海西湖凹陷花港组煤层特征及控制因素研究

    Institute of Scientific and Technical Information of China (English)

    张虎; 郭英海; 赵志刚; 蔡佳; 王飞

    2014-01-01

    In order to study development features of the seams in Huagang Formation of Xihu Depression,the paper discussed the major control factors of the seams development.The statistic analysis method of the well logging and recording data in the study zone,the sedimen-tology graphic and map analysis and other method were applied to study the formation environment and development features of the seams. The results showed that the distribution of the seams in Huagang Formation was wide and the thickness variation was high.Along the expan-sion direction of the basin,the seams were symmetrical distributed,the distributions of the seams were nonuniform and the features of the north and south zones were obvious.During the sedimentary period of the Huangang Formation,Xihu Depression was in the depression peri-od and the development of the fluvial facies-delta facies-lacustrine facies sedimentary environment would be favorable to the coal forma-tion.The seam distribution features were affected by the basic floor features and the sedimentary environment control and the paper pointed out that the sedimentary environment was the main factors of the seam development.%为了研究西湖凹陷花港组煤层发育特征,探讨煤层发育主要控制因素,运用研究区测井、录井数据统计分析及沉积学图件分析等方法,研究煤层形成环境及发育特征,结果表明:西湖凹陷花港组煤层具有分布广泛,厚度变化大,煤层沿盆地延伸方向上对称分布,煤层分布不均匀,南北分带明显的特点。西湖凹陷花港组沉积时期,西湖凹陷处于坳陷期,发育河流相-三角洲相-湖泊相沉积环境,易于成煤。煤层分布特点受基底特征及沉积环境控制影响,同时指出沉积环境为煤层发育的主控因素。

  12. Differing Styles of Magmatic Emplacement and the Formation of Different Crustal Types during the Opening of Back-Arc Basins, a Case in Point from the East Sea/Sea of Japan

    Science.gov (United States)

    Lee, S. M.

    2016-12-01

    The key issue in understanding the geology of back-arc basins is their similarity and difference with global mid-ocean ridges. Studies of back-arc basins are difficult relative to ridges because they often lie beneath thick sediment and are split by political boundaries. The Sea of Japan also known as the East Sea of Korea comprises of three major back-arc basins with unique characteristics, and thus may be a good place to investigate the processes that determine the framework of back-arc basins. The Japan Basin which opened up first around 32 Ma represents a classic example of an oceanic crust developed at a ridge-like setting. With 6-7 km thick crust, it has smooth seafloor where magnetic anomaly patterns can be well-recognized, suggesting that emplacement of crust occurred at a narrow strip (neovolcanic zone). Such characteristics contrast with those basins in the southwest that developed later. In both the Yamato and Ulleung basins, the seafloor is underlain by a thick crust (10-15 km), twice that of typical oceanic crust. No magnetic anomaly patterns could be recognized, and yet this crust is often referred to as `thicker oceanic crust' or `anomalous-thick oceanic crust' because the seismic velocity structure resembles that of normal oceanic crust at the top. However, recent detailed study by Sato and others finds that the velocity of the thick crust under Yamato basin is lower than that of mid-ocean ridges of similar age. The crust is uniformly thick in both the Yamato and Ulleung basins, an observation which was not obvious in the latter case due thick sediment but confirmed by the analysis of gravity anomaly. I argue that the mode of emplacement during the early stages of opening was quite different in the case of these two basins close to the continent. A large buoyancy involving a rapid upwelling of large melt is likely to have been the dominant force as opposed to uniform forces exerted by steady plate separation. Also unlike mid-ocean ridges, the sudden

  13. Petrologic and geochemical characterization and mineralization of the metavolcanic rocks of the Heib Formation, Kid Metamorphic Complex, Sinai, Egypt

    Directory of Open Access Journals (Sweden)

    Ibrahim H. Khalifa

    2011-07-01

    Full Text Available Metavolcanic rocks hosting base metal sulphide mineralization, and belonging to the Kid Metamorphic Complex, are exposed in the Samra-Tarr area, Southern Sinai. The rocks consist of slightly metamorphosed varicolored porphyritic lavas of rhyolite-to-andesite composition, and their equivalent pyroclastics. Geochemically, these metavolcanics are classified as high-K calc-alkaline, metaluminous andesites, trachyandesites, dacites, and rhyolites. The geochemical characteristics of these metavolcanics strongly point to their derivation from continental crust in an active continental margin. The sulphide mineralization in these metavolcanics occurs in two major ore zones, and is represented by four distinct styles of mineralization. The mineralization occurs either as low-grade disseminations or as small massive pockets. The associated hydrothermal alterations include carbonatization, silicification, sericitization and argillic alterations. The base metal sulphide mineralization is epigenetic and was formed by hydrothermal solutions associated with subduction-related volcanic activity.

  14. Petrology and geochemistry of the ~2.9 Ga Itilliarsuk banded iron formation and associated supracrustal rocks, West Greenland

    DEFF Research Database (Denmark)

    Haugaard, Rasmus; Frei, Robert; Stendal, Henrik

    2013-01-01

    or outer shelf environment, with frequent fluctuations of epiclastic and volcanogenic sediments derived from adjacent bimodal sources. The TDM model ages and the use of Th–Sc–Zr and La–Th–Sc tectonic discrimination plots indicate that the metasediments were sourced from a juvenile ocean island arc setting....

  15. Yanshanian Magma-Tectonic-Metallogenic Belt in East China of Circum-Pacific Domain (Ⅰ):Igneous Rocks and Orogenic Processes

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Yanshanian igneous rocks in the East China, on an orogenic belt scale, are characterized by the continental marginal arc in petrology and geochemistry as Andes and West USA, except for the Hercyn-type biotite-two mica-muscovite granite belt in the Nanling region. Three segments of the Yanshanian igneous rocks along the belt are recognized. In terms of magma-tectonic event sequence, the north, middle and south segments have counter-clockwise (ccw), clockwise (cw) and ccw+cw pTt paths of the orogenic process, respectively. A genetic model of the lithospheric delamination (loss of the lithospheric root in about 120 km) in combination with the oceanic subduction for the Yanshanian Andes-like orogenic belt and both the crust and lithosphere thickening for the Yanshanian Hercyn-type Nanling orogenic belt in the East China is suggested.

  16. Experimental petrology for the thermobarometric determination of mineral paragenesis: the fluid inclusions; Petrologia experimental para la determinacion termobarometrica de paragenesis minerales: las inclusiones fluidas

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Partida, Eduardo; Torres Rodriguez, Vicente; Birkle, Peter [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1994-05-01

    There is a great number of phenomena in nature in which some fluid participates as the main component. Such is the case of oil deposits formation, of metallic minerals, geothermal systems, metamorphic and diagenetic deposits. The common denominator of all of them is that in some part of their stages important physico-chemical processes occurred in the related fluids, leaving evidence of such phenomena in the fluid inclusions. The Geothermal Department has petrologic vanguard tools for reservoir problems resolution, since it has laboratories for the study on fluid inclusions by means of the technique called cryoscopic-microthermometry that permits the definition of physico-chemical conditions of the brine that participated or participates in the hydrothermal systems formation. The method simultaneously permits to know the characteristics of the initial brine that participated in the interaction water-rock phenomenon, observe the boiling phenomena, and determine conditions of initial pressure in the reservoirs. [Espanol] Existe un gran numero de fenomenos en la naturaleza en los que participa algun fluido como componente principal. Tal es el caso de la formacion de yacimientos de petroleo, de minerales metalicos, de sistemas geotermicos, yacimientos metamorficos y diageneticos. El comun denominador de todos ellos es que en alguna de sus etapas ocurrieron procesos fisicoquimicos importantes en los fluidos relacionados, quedando evidencia de tales fenomenos en las inclusiones fluidas. El Departamento de Geotermia cuenta con herramientas petrologicas de vanguardia para la resolucion de problemas en yacimientos, ya que tiene laboratorios para el estudio de las inclusiones fluidas por medio de la tecnica denominada microtermometria-crioscopica que permite definir condiciones fisicoquimicas de la salmuera que participo o participa en la formacion de sistemas hidrotermales. El metodo permite simultaneamente conocer las caracteristicas de la salmuera inicial que participo en

  17. East Candor Chasma

    Science.gov (United States)

    1997-01-01

    During its examination of Mars, the Viking 1 spacecraft returned images of Valles Marineris, a huge canyon system 5,000 km long, up to 240 km wide, and 6.5 km deep, whose connected chasma or valleys may have formed from a combination of erosional collapse and structural activity. The view shows east Candor Chasma, one of the connected valleys of Valles Marineris; north toward top of frame; for scale, the impact crater in upper right corner is 15 km (9 miles) wide. The image, centered at latitude 7.5 degrees S., longitude 67.5 degrees, is a composite of Viking 1 Orbiter high-resolution (about 80 m/pixel or picture element) images in black and white and low-resolution (about 250 m/pixel) images in color. The Viking 1 craft landed on Mars in July of 1976. East Candor Chasma occupies the eastern part of the large west-northwest-trending trough of Candor Chasma. This section is about 150 km wide. East Candor Chasma is bordered on the north and south by walled cliffs, most likely faults. The walls may have been dissected by landslides forming reentrants; one area on the north wall shows what appears to be landslide debris. Both walls show spur-and-gully morphology and smooth sections. In the lower part of the image northwest-trending, linear depressions on the plateau are younger graben or fault valleys that cut the south wall. Material central to the chasma shows layering in places and has been locally eroded by the wind to form flutes and ridges. These interior layered deposits have curvilinear reentrants carved into them, and in one locale a lobe flows away from the top of the interior deposit. The lobe may be mass-wasting deposits due to collapse of older interior deposits (Lucchitta, 1996, LPSC XXVII abs., p. 779- 780); this controversial idea requires that the older layered deposits were saturated with ice, perhaps from former lakes, and that young volcanism and/or tectonism melted the ice and made the material flow.

  18. Configurating Study of High Fluoride Groundwater Formation Mechanism in East Henan Plain%高氟地下水形成的组态分析——以豫东平原区为例

    Institute of Scientific and Technical Information of China (English)

    宁立波; 徐恒力

    2012-01-01

    The study of high fluoride groundwater formation mechanism is very important. Under the guidance of system theory, classification of traditional water chemistry was improved and configurating analysis was used to study the formation mechanism. It was found that high fluoride groundwater was formed by synergic functions of multiple components. As for non-linear system, high fluoride groundwater formation was polymorphic. As for one section, it was a temporary state, and continually changing. The high probability of water chemistry configurate of Na+ > Ca2+ was more than Na+ < Ca2+ type. In high fluoride groundwater, water chemistry configurates of Na. Mg. Ca-H.S.C and Na.Mg.Ca-H.C.S were representative, with high probability as 86% and 76% respectively.%高氟地下水的形成机理研究是目前相关理论研究的关键问题,文章在系统思想指导下将传统的水化学类型分类方法进行改进,以组态分析的方法进行形成机理研究,得出以下结论:(1)高氟地下水的形成是多因子协同作用的结果;(2)作为非线性系统,高氟地下水的形成是个多态问题,就某一个区段而言是一个“暂态”,一直处于多态的变化过程中,在此过程中各个因子相互作用形成多组态;(3)Na+>Ca2+型的水化学组态的高氟率(平均51%)明显大于Na+<Ca+型(平均12%),在高氟区段,具有代表性的水化学组态有Na·Mg·Ca-H·S·C、Na·Mg· Ca-H·C·S,其高氟概率分别为86%、76%.

  19. Geochemistry and petrology of selected coal samples from Sumatra, Kalimantan, Sulawesi, and Papua, Indonesia

    Science.gov (United States)

    Belkin, H.E.; Tewalt, S.J.; Hower, J.C.; Stucker, J.D.; O'Keefe, J. M. K.

    2009-01-01

    Indonesia has become the world's largest exporter of thermal coal and is a major supplier to the Asian coal market, particularly as the People's Republic of China is now (2007) and perhaps may remain a net importer of coal. Indonesia has had a long history of coal production, mainly in Sumatra and Kalimantan, but only in the last two decades have government and commercial forces resulted in a remarkable coal boom. A recent assessment of Indonesian coal-bed methane (CBM) potential has motivated active CBM exploration. Most of the coal is Paleogene and Neogene, low to moderate rank and has low ash yield and sulfur (generally coal basins. Eight coal samples are described that represent the major export and/or resource potential of Sumatra, Kalimantan, Sulawesi, and Papua. Detailed geochemistry, including proximate and ultimate analysis, sulfur forms, and major, minor, and trace element determinations are presented. Organic petrology and vitrinite reflectance data reflect various precursor flora assemblages and rank variations, including sample composites from active igneous and tectonic areas. A comparison of Hazardous Air Pollutants (HAPs) elements abundance with world and US averages show that the Indonesian coals have low combustion pollution potential.

  20. Petrology of the Devonian gas-bearing shale along Lake Erie helps explain gas shows

    Energy Technology Data Exchange (ETDEWEB)

    Broadhead, R.F.; Potter, P.E.

    1980-11-01

    Comprehensive petrologic study of 136 thin sections of the Ohio Shale along Lake Erie, when combined with detailed stratigraphic study, helps explain the occurrence of its gas shows, most of which occur in the silty, greenish-gray, organic poor Chagrin Shale and Three Lick Bed. Both have thicker siltstone laminae and more siltstone beds than other members of the Ohio Shale and both units also contain more clayshales. The source of the gas in the Chagrin Shale and Three Lick Bed of the Ohio Shale is believed to be the bituminous-rich shales of the middle and lower parts of the underlying Huron Member of the Ohio Shale. Eleven petrographic types were recognized and extended descriptions are provided of the major ones - claystones, clayshales, mudshales, and bituminous shales plus laminated and unlaminated siltstones and very minor marlstones and sandstones. In addition three major types of lamination were identified and studied. Thirty-two shale samples were analyzed for organic carbon, whole rock hydrogen and whole rock nitrogen with a Perkin-Elmer 240 Elemental Analyzer and provided the data base for source rock evaluation of the Ohio Shale.

  1. Evidence for a Single Ureilite Parent Asteroid from a Petrologic Study of Polymict Ureilites

    Science.gov (United States)

    Downes, Hilary; Mittlefehldt, David W.

    2006-01-01

    Ureilites are ultramafic achondrites composed of olivine and pyroxene, with minor elemental C, mostly as graphite [1]. The silicate composition indicates loss of a basaltic component through igneous processing, yet the suite is very heterogeneous in O isotopic composition inherited from nebular processes [2]. Because of this, it has not yet been established whether ureilites were derived from a single parent asteroid or from multiple parents. Most researchers tacitly assume a single parent asteroid, but the wide variation in mineral and oxygen isotope compositions could be readily explained by an origin in multiple parent asteroids that had experienced a similar evolution. Numerous ureilite meteorites have been found in Antarctica, among them several that are clearly paired (Fig. 1) and two that are strongly brecciated (EET 83309, EET 87720). We have begun a detailed petrologic study of these latter two samples in order to characterize the range of materials in them. One goal is to attempt to determine whether ureilites were derived from a single parent asteroid.

  2. Permian Mengkarang coal facies and environment, based on organic petrology study

    Directory of Open Access Journals (Sweden)

    Nana Suwarna

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol1no1.20061aThe Permian Mengkarang Coal Measures is situated in the middle part of Sumatera Island. Some fresh outcrop samples of the Permian Mengkarang coals have been analyzed both macroscopically and microscopically, to asses their depositional environment. On the basis of organic-petrological analysis, the coal seams show variation in the predominance of some macerals, indicating successions of environmental changes. The dominant maceral group is vitrinite, present in very low to very high values; whilst the minor one is inertinite showing low amount. Environmental information derived from the organic facies study shows that the coals were deposited in wet zone of mire, ranges from wet limnic-telmatic zone to telmatic wet forest swamp under rapid burial condition, due to rapid basin subsidence. The organic facies concept is thus applicable in basin studies context and has potential to become an additional tool for interpretation of depositional environment.    

  3. Drmno lignite field (Kostolac basin, Serbia: Origin and palaeoenvironmental implications from petrological and organic geochemical studies

    Directory of Open Access Journals (Sweden)

    Stojanović Ksenija

    2012-01-01

    Full Text Available The objective of the study was to determine the origin and to reconstruct the geological evolution of lignites from the Drmno field (Kostolac Basin, Serbia. For this purpose petrological and organic geochemical analyses were used. Coal from the Drmno field is typical humic coal. Peat-forming vegetation dominated by decay of resistant gymnosperm (coniferous plants, followed by prokaryotic organisms and angiosperms. Coal forming plants belonged to the gymnosperm families Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae and Pinaceae. Peatification was performed in neutral to slightly acidic, fresh water environment. Considering that organic matter of Drmno lignites was deposited at the same time, in the relatively constant climate, it could be supposed that climate probably had only small impact on peatification. Therefore, variations in compositions of macerals and biomarkers indicate changes in the water level, due to seasonal drying of the mire, which caused vegetation differences in the palaeoplant communities and changes of redox conditions (from anoxic to slightly oxic during peatification. Diagenetic transformations of the organic matter were mainly governed by microbial activity, rather than thermal alteration.

  4. Magmatic differentiation processes at Merapi Volcano: inclusion petrology and oxygen isotopes

    Science.gov (United States)

    Troll, Valentin R.; Deegan, Frances M.; Jolis, Ester M.; Harris, Chris; Chadwick, Jane P.; Gertisser, Ralf; Schwarzkopf, Lothar M.; Borisova, Anastassia Y.; Bindeman, Ilya N.; Sumarti, Sri; Preece, Katie

    2013-07-01

    Indonesian volcano Merapi is one of the most hazardous volcanoes on the planet and is characterised by periods of active dome growth and intermittent explosive events. Merapi currently degasses continuously through high temperature fumaroles and erupts basaltic-andesite dome lavas and associated block-and-ash-flows that carry a large range of magmatic, coarsely crystalline plutonic, and meta-sedimentary inclusions. These inclusions are useful in order to evaluate magmatic processes that act within Merapi's plumbing system, and to help an assessment of which phenomena could trigger explosive eruptions. With the aid of petrological, textural, and oxygen isotope analysis we record a range of processes during crustal magma storage and transport, including mafic recharge, magma mixing, crystal fractionation, and country rock assimilation. Notably, abundant calc-silicate inclusions (true xenoliths) and elevated δ18O values in feldspar phenocrysts from 1994, 1998, 2006, and 2010 Merapi lavas suggest addition of limestone and calc-silicate materials to the Merapi magmas. Together with high δ13C values in fumarole gas, crustal additions to mantle and slab-derived magma and volatile sources are likely a steady state process at Merapi. This late crustal input could well represent an eruption trigger due to sudden over-pressurisation of the shallowest parts of the magma storage system independently of magmatic recharge and crystal fractionation. Limited seismic precursors may be associated with this type of eruption trigger, offering a potential explanation for the sometimes erratic behaviour of Merapi during volcanic crises.

  5. The Danish East India Company

    DEFF Research Database (Denmark)

    Sørensen, Karsten Engsig

    2005-01-01

    The article analysis the first Danish East India Company incorporated in 1616, which was the first Danish Stock Company and which has impacts even on modern Danish company la......The article analysis the first Danish East India Company incorporated in 1616, which was the first Danish Stock Company and which has impacts even on modern Danish company la...

  6. Organic geochemical study of sequences overlying coal seams; example from the Mansfield Formation (Lower Pennsylvanian), Indiana

    Science.gov (United States)

    Mastalerz, Maria; Stankiewicz, A.B.; Salmon, G.; Kvale, E.P.; Millard, C.L.

    1997-01-01

    Roof successions above two coal seams from the Mansfield Formation (Lower Pennsylvanian) in the Indiana portion of the Illinois Basin have been studied with regard to sedimentary structures, organic petrology and organic geochemistry. The succession above the Blue Creek Member of the Mansfield Formation is typical of the lithologies covering low-sulphur coals ( 2.%). The transgressive-regressive packages above both seams reflect the periodic inundation of coastal mires by tidal flats and creeks as inferred from bioturbation and sedimentary structures such as tidal rhythmites and clay-draped ripple bedforms. Geochemistry and petrology of organic facies above the Blue Creek coal suggest that tidal flats formed inland in fresh-water environments. These overlying fresh water sediments prevented saline waters from invading the peat, contributing to low-sulphur content in the coal. Above the unnamed coal, trace fossils and geochemical and petrological characteristics of organic facies suggest more unrestricted seaward depositional environment. The absence of saline or typically marine biomarkers above this coal is interpreted as evidence of very short periods of marine transgression, as there was not enough time for establishment of the precursor organisms for marine biomarkers. However, sufficient time passed to raise SO42- concentration in pore waters, resulting in the formation of authigenic pyrite and sulphur incorporation into organic matter.

  7. U-Pb zircon geochronology and phase equilibria modelling of a mafic eclogite from the Sumdo complex of south-east Tibet: Insights into prograde zircon growth and the assembly of the Tibetan plateau

    Science.gov (United States)

    Weller, O. M.; St-Onge, M. R.; Rayner, N.; Waters, D. J.; Searle, M. P.; Palin, R. M.

    2016-10-01

    The Sumdo complex is a Permian-Triassic eclogitic metamorphic belt in south-east Tibet, which marks the location of a suture zone that separates the northern and southern Lhasa terranes. An integrated geochronological and petrological study of a mafic eclogite from the complex has constrained its tectonometamorphic history and provides a case study of zircon growth in eclogite as a product of prograde dissolution-precipitation. In situ U-Pb geochronology indicates that the eclogite contains a single population of zircon with a crystallisation age of 273.6 ± 2.8 Ma. The morphology and chemistry of the zircon grains are consistent with growth by dissolution-precipitation of protolith magmatic zircon. The presence of zircon grains as inclusions in the cores of peak phases indicates that zircon dissolution-precipitation occurred during prograde metamorphism, and calculated pressure and temperature conditions over which mineral inclusions in zircon are stable suggest that the zircon most likely precipitated at 15.5-16.5 kbar and 500-560 °C. Subsequent peak metamorphism is calculated to have reached pressure-temperature conditions of 27 ± 1 kbar and 670 ± 50 °C. Previous studies, which have documented a range of peak metamorphic conditions from high- to ultrahigh-pressure at c. 266-230 Ma, indicate that the Sumdo complex is a composite belt that experienced protracted eclogite exhumation. The results of this study are consistent with this interpretation, and extend the age range of high-pressure metamorphism in the complex to over 40 Myr. Analysis of published pressure-temperature-time data indicates two systematic behaviours within this spread. First, peak metamorphic temperatures declined over time. Second, eclogite exhumation occurred in two discrete intervals: soon after formation, and during the demise of the subduction zone. The latter behaviour serves as a reminder that eclogite exhumation is the exception rather than the rule.

  8. Petrological Characteristics and Original Rocks for Metamorphic Rocks from the Jinmo Sb Deposit, in Quang Ninh Province, Vietnam%越南广宁晋磨锑矿床变质岩石特征及原岩恢复

    Institute of Scientific and Technical Information of China (English)

    季根源; 戴塔根; 孔令湖; 姜爱玲

    2015-01-01

    The Jinmo Sb deposit lies in the collision boundary between the Indo-Chinese block and the South China block, and is close to the east side of the Honghe strike-slip fault and belongs to the South China block. The study of petrology and geochemistry of metamorphic rocks in this region indicates that the original rocks are greywacke, carbonaceous argillaceous sandstone, argillaceous sandstone and clay rock.%晋磨锑矿床位于印支地块和华南地块碰撞界限的边缘,紧靠红河走滑大断裂的东侧,属于华南地块。对研究区变质岩的岩石学、地球化学研究表明,该矿床变质岩均为浅变质的副变质岩,其原岩主要为杂砂岩,其次为泥质砂岩、含炭泥质砂岩,粘土岩。

  9. Agreement on Water and a Watered-Down Agreement: The Political Ecology of Contested Coastal Development in Down East, North Carolina

    Science.gov (United States)

    Campbell, Lisa M.; Meletis, Zoe A.

    2011-01-01

    In 2006, land use planning emerged as a contested issue in the rural area known as "Down East", Carteret County, in eastern North Carolina, USA. Down East is experiencing a transition from a commercial fishing to an amenity economy and concerns about related changes led to the formation of "Down East Tomorrow" (DET), a…

  10. East Asian Studies of Tropospheric Aerosols and their Impact on Regional Climate (EAST -AIRC): An overview

    Science.gov (United States)

    Zhangqing, Li; Li, C.; Chen, H.; Tsay, S.-C.; Holben, B.; Huang, J.; Li, B.; Maring, H.; Qian, Y.; Shi, G.; Xia, X.; Yin, Y.; Zheng, Y.; Zhuang, G.

    2011-01-01

    As the most populated region of the world, Asia is a major source of aerosols with potential large impact over vast downstream areas, Papers published in this special section describe the variety of aerosols observed in China and their effects and interactions with the regional climate as part of the East Asian Study of Tropospheric Aerosols and their Impact on Regional Climate (EAST-AIRC), The majority of the papers are based on analyses of observations made under three field projects, namely, the Atmospheric Radiation Measurements (ARM) Mobile Facility mission in China (AMF-China), the East Asian Study of Tropospheric Aerosols: An International Regional Experiment (EAST-AIRE), and the Atmospheric Aerosols of China and their Climate Effects (AACCE), The former two are U,S,-China collaborative projects, and the latter is a part of the China's National Basic Research program (or often referred to as "973 project"), Routine meteorological data of China are also employed in some studies, The wealth of general and speCIalized measurements lead to extensive and close-up investigations of the optical, physical, and chemical properties of anthropogenic, natural, and mixed aerosols; their sources, formation, and transport mechanisms; horizontal, vertical, and temporal variations; direct and indirect effects; and interactions with the East Asian monsoon system, Particular efforts are made to advance our understanding of the mixing and interaction between dust and anthropogenic pollutants during transport. Several modeling studies were carried out to simulate aerosol impact on radiation budget, temperature, precipitation, wind and atmospheric circulation, fog, etc, In addition, impacts of the Asian monsoon system on aerosol loading are also simulated.

  11. East Mariana Basin tholeiites: Cretaceous intraplate basalts or rift basalts related to the Ontong Java plume?

    Science.gov (United States)

    Castillo, P.R.; Pringle, M.S.; Carlson, R.W.

    1994-01-01

    Studies of seafloor magnetic anomaly patterns suggest the presence of Jurassic oceanic crust in a large area in the western Pacific that includes the East Mariana, Nauru and Pigafetta Basins. Sampling of the igneous crust in this area by the Deep Sea Drilling Program (DSDP) and the Ocean Drilling Program (ODP) allows direct evaluation of the age and petrogenesis of this crust. ODP Leg 129 drilled a 51 m sequence of basalt pillows and massive flows in the central East Mariana Basin. 40Ar 39Ar ages determined in this study for two Leg 129 basalts average 114.6 ?? 3.2 Ma. This age is in agreement with the Albian-late Aptian paleontologic age of the overlying sediments, but is distinctively younger than the Jurassic age predicted by magnetic anomaly patterns in the basin. Compositionally, the East Mariana Basin basalts are uniformly low-K tholeiites that are depleted in highly incompatible elements compared to moderately incompatible ones, which is typical of mid-ocean ridge basalts (MORB) erupted near hotspots. The Sr, Nd and Pb isotopic compositions of the tholeiites ( 87Sr 86Srinit = 0.70360-0.70374; 143Nd 144Ndinit = 0.512769-0.512790; 206Pb 204Pbmeas = 18.355-18.386) also overlap with some Indian Ocean Ridge MORB, although they are distinct from the isotopic compositions of Jurassic basalts drilled in the Pigafetta Basin, the oldest Pacific MORB. The isotopic compositions of the East Mariana Basin tholeiites are also similar to those of intraplate basalts, and in particular, to the isotopic signature of basalts from the nearby Ontong Java and Manihiki Plateaus. The East Mariana Basin tholeiites also share many petrologic and isotopic characteristics with the oceanic basement drilled in the Nauru Basin at DSDP Site 462. In addition, the new 110.8 ?? 1.0 Ma 40Ar 39Ar age for two flows from the bottom of Site 462 in the Nauru Basin is indistinguishable from the age of the East Mariana Basin flows. Thus, while magnetic anomaly patterns predict that the igneous

  12. Depositional setting, petrology and chemistry of Permian coals from the Paraná Basin: 2. South Santa Catarina Coalfield, Brazil

    Science.gov (United States)

    Kalkreuth, W.; Holz, M.; Mexias, A.; Balbinot, M.; Levandowski, J.; Willett, J.; Finkelman, R.; Burger, H.

    2010-01-01

    In Brazil economically important coal deposits occur in the southern part of the Paran?? Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata, and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Paran?? Basin.In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment, with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapu??, Barro Branco and Treviso seams).Seam thicknesses range from 1.70 to 2.39. m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapu?? seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapu?? seam has the highest inertinite content (33.8. vol%). Liptinite mean values range from 7.8. vol% (Barro Branco seam) to 22.5. vol% (Irapu?? seam).Results from proximate analyses indicate for the three seams high ash yields (50.2 - 64.2wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (>50wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the

  13. On the nature and origin of highly-refractory Archean lithosphere: Petrological and geophysical constraints from the Tanzanian craton

    Science.gov (United States)

    Gibson, S. A.; McMahon, S. C.; Day, J. A.; Dawson, J. B.

    2012-12-01

    The nature and timescales of garnet formation are important to understanding how subcontinental lithospheric mantle (SCLM) has evolved since the Archean, and also to mantle dynamics, because the presence of garnet greatly influences the density of the lower lithosphere and hence the long-term stability of thick (150 to 220 km) subcratonic lithosphere. Nevertheless, the widespread occurrence of garnet in the SCLM remains one of the 'holy grails' of mantle petrology. Garnets found in mantle xenoliths from the eastern margin of the Tanzanian Craton (Lashaine) have diverse compositions and provide major constraints on how the underlying deep (120 to 160 km) mantle evolved during the last 3 billion years. Certain harzburgite members of the xenolith suite contain the first reported occurrence of pyrope garnets with rare-earth element patterns similar to hypothetical garnets proposed to have formed in the Earth's SCLM during the Archean, prior to metasomatism [Stachel et al., 2004]. These rare ultradepleted low-Cr garnets occur in low temperature (~1050 oC) xenoliths derived from depths of ~120 km and coexist in chemical and textural equilibrium with highly-refractory olivine (Fo95.4) and orthopyroxene (Mg#=96.4). These phases are all more magnesian than generally encountered in global mantle harzburgites and diamond inclusions. The ultradepleted garnets form interconnecting networks around grains of orthopyroxene which give the rocks a banded appearance: we propose that the increase in pressure associated with cratonization may have caused isochemical exsolution of ultradepleted garnet from orthopyroxene. These unique garnets have not previously been identified in global suites of mantle xenoliths or diamond inclusions. We believe they are rare because their low concentrations of trace elements make them readily susceptible to geochemical overprinting. This highly-refractory low-density peridotite may be common in the 'shallow' SCLM but not normally brought to the

  14. Seismic wave velocity of rocks in the Oman ophiolite: constraints for petrological structure of oceanic crust

    Science.gov (United States)

    Saito, S.; Ishikawa, M.; Shibata, S.; Akizuki, R.; Arima, M.; Tatsumi, Y.; Arai, S.

    2010-12-01

    Evaluation of rock velocities and comparison with velocity profiles defined by seismic refraction experiments are a crucial approach for understanding the petrological structure of the crust. In this study, we calculated the seismic wave velocities of various types of rocks from the Oman ophiolite in order to constrain a petrological structure of the oceanic crust. Christensen & Smewing (1981, JGR) have reported experimental elastic velocities of rocks from the Oman ophiolite under oceanic crust-mantle conditions (6-430 MPa). However, in their relatively low-pressure experiments, internal pore-spaces might affect the velocity and resulted in lower values than the intrinsic velocity of sample. In this study we calculated the velocities of samples based on their modal proportions and chemical compositions of mineral constituents. Our calculated velocities represent the ‘pore-space-free’ intrinsic velocities of the sample. We calculated seismic velocities of rocks from the Oman ophiolite including pillow lavas, dolerites, plagiogranites, gabbros and peridotites at high-pressure-temperature conditions with an Excel macro (Hacker & Avers 2004, G-cubed). The minerals used for calculations for pillow lavas, dolerites and plagiogranites were Qtz, Pl, Prh, Pmp, Chl, Ep, Act, Hbl, Cpx and Mag. Pl, Hbl, Cpx, Opx and Ol were used for the calculations for gabbros and peridotites. Assuming thermal gradient of 20° C/km and pressure gradient of 25 MPa/km, the velocities were calculated in the ranges from the atmospheric pressure (0° C) to 200 MPa (160° C). The calculation yielded P-wave velocities (Vp) of 6.5-6.7 km/s for the pillow lavas, 6.6-6.8 km/s for the dolerites, 6.1-6.3 km/s for the plagiogranites, 6.9-7.5 km/s for the gabbros and 8.1-8.2 km/s for the peridotites. On the other hand, experimental results reported by Christensen & Smewing (1981, JGR) were 4.5-5.9 km/s for the pillow lavas, 5.5-6.3 km/s for the dolerites, 6.1-6.3 km/s for the plagiogranites, 6

  15. Petrology of some Mexican mesozoic-cenozoic plutons: Sources and tectonic environments

    Science.gov (United States)

    Stein, G.; Lapierre, H.; Monod, O.; Zimmermann, J.-L.; Vidal, R.

    1994-01-01

    In central and southern Mexico, three Late Mesozoic to Early Tertiary plutonic suites have been investigated. They record the evolution of the Mexican Pacific margin through space and time and more specifically its crustal thickness. In Central Mexico the La Angostura pluton (110-100 Ma) is calc-alkaline and intrudes a Late Jurassic-Early Cretaceous exotic arc, represented by the Guanajuato magmatic sequence. Both pluton and country rocks were affected by a greenschist facies metamorphism. Their high ɛNd(i) and low ɛSr(i) values are more or less similar to those of the Guanajuato arc tholeiitic rocks and suggest that both the calc-alkaline intrusions and the arc tholeiitic suite were derived from a mantle source essentially uncontaminated by a crustal component. The La Angostura calc-alkaline plutonic rocks could represent the remnants of the mature stage of this arc before its tectonic emplacement on the western margin of the North American craton. In the vicinity of the La Angostura pluton, the Eocene (ɛ50 Ma) Comanja and La Estancia granodiorites are chemically similar to volcanic arc granites and their low ɛNd(i) and high ɛSr(i) ratios suggest that they were derived from a mantle source highly contaminated by continental crust. Finally, the youngest plutonic suite (38 Ma), exposed near Zihuatanejo ranges from gabbro to granodiorite and displays calc-alkaline compositional features. Their ɛNd(i) and ɛSr(i) ratios indicate that the Zihuatanejo plutonic suite was derived from a mantle source which has been weakly contaminated by subducted sediments and/or continental crust. The contrasting petrology, chemistry and isotopic ratios of the Comanja-La Estancia granodiorites and the Zihuatanejo gabbro-granodiorite suite reflect a difference in thickness of their continental basement.

  16. The topography of the Iberian Peninsula from coupled geophysical-petrological inversion of multiple data sets

    Science.gov (United States)

    Fullea, Javier; Negredo, Ana; Charco, María; Palomeras, Imma; Villaseñor, Antonio; Afonso, Juan Carlos

    2017-04-01

    In this study we have performed a1D nonlinear Bayesian (probabilistic) inversion of a wide variety of data sets, extensively exploring the parameter space by means of a coupled geophysical-petrological inversion algorithm. The goal is to obtain a robust estimation of the thermal, compositional and density structure of the lithospheric/sublithospheric upper mantle system beneath the Iberian Peninsula, a crucial constraint to understand the complex geodynamic evolution in the study area. The most prominent feature in the modeled lithospheric structure is the progressive northward and northeastward steepening of the lithospheric-asthenospheric boundary (LAB) below the Ebro basin, reaching > 120 km under the central and western Pyrenees. Similarly, absolute maximum values of crustal thickness are obtained in the central Pyrenees, locally exceeding 45 km. Further to the west the Moho discontinuity shallows to about 35 km beneath the Cantabrian Cordillera. A dramatic decrease in both crustal and lithospheric thickness is observed from the central towards the easternmost Pyrenees, reaching depths of about 25 km and 90 km for the Moho and LAB respectively. Average Moho depth values of about 30 km are estimated in the central Iberian Peninsula. A slightly thicker crust is predicted under the Gibraltar arc than under the Betics, consistently with the deeper LAB beneath the former, most likely reflecting the presence of a sinking lithospheric slab. For the rest of the Iberian Peninsula a rather flat topography of LAB and Moho is observed, with moderate lithospheric thinning below the central western and SE Iberian margins. Isostatic topography related to variations in predicted crustal thickness shows local significant discrepancies form observed topography, thus indicating important regional contributions from dynamic and mantle source. The thermal and compositional fields in the lithospheric reveal the imprints of past and ongoing tectonic processes that have their

  17. Igneous rocks of Arctic Ocean deep sea ridges: new data on petrology, geochemistry and geochronology

    Science.gov (United States)

    Petrov, Oleg; Morozov, Andrey; Shokalsky, Sergey; Sobolev, Nikolay; Kashubin, Sergey; Shevchenko, Sergey; Sergeev, Sergey; Belyatsky, Boris; Shatov, Vitaly; Petrov, Eugeny

    2015-04-01

    The aggregate results of studies of igneous rocks, collected from the central part of the Arctic Ocean during scientific marine expeditions «Arctic-2000, 2005, 2007 and 2012» are presented and discussed in the frame of modern understanding of High Polar Arctic tectonic constraint. Petrological, geochemical and isotope-geochronological studies of more than 500 samples have shown that the sedimentary rocks are of dominated population among the rock fragments dredged from deep-sea bottom, and represented by metamorphosed dolomite and quartz sandstone, limestone, sometimes with the Devonian - Permian fauna. Igneous rocks are 10-15% only (Archean and Paleoproterozoic gneissouse granites and gabbro, Neoproterozoic dolerite) and metamorphic rocks (green shales, metabasites, gneisses). Apparently, these rocks are part of the acoustic basement underlying the Late Mesozoic - Cenozoic layered loose sediments. In addition to the dredged fragments of the ancient mafic rocks, some samples were taken as a core during deep-water drilling in the northern and southern slopes of the Mendeleev Ridge and represented by trachybasalts, marking the border of Late-Cenozoic deposit cover and acoustic basement and quite similar in composition to those of Early-Late Cretaceous basalts form northward of the Chukchi Plateau seamounts, Alpha Ridge, Franz Josef Land, De Long islands and other parts of the large igneous province of the High Arctic (HALIP). Video-filming of Mendeleev Ridge escarps proofs the existing of rock outcrops and supports local origin of most of the rock fragments found in the sampling areas. Thus the continental type of the earth's crust of the Central Arctic Ridges basement is based on all obtained results of our study of sea-bottom excavated rock material.

  18. A glimpse into Augustine Volcano's Pleistocene past: Insight from the petrology of a massive rhyolite deposit

    Science.gov (United States)

    Nadeau, Patricia A.; Webster, James D.; Mandeville, Charles W.; Goldoff, Beth A.; Shimizu, Nobumichi; Monteleone, Brian

    2015-10-01

    Activity at Augustine Volcano, Alaska, has been characterized by intermediate composition domes, flows, and tephras during the Holocene. Erosive lahars and pyroclastic flows associated with the 2006 eruption revealed large exposures of voluminous rhyolite pumice fall beneath glacial tills; the massive rhyolite deposit is evidence of anomalously large prehistoric eruptions. The rhyolite is petrologically and mineralogically different from more recent eruptive products, with abundant amphibole (calcic amphiboles and cummingtonite) and quartz. Three texturally and chemically distinct lithologies are present. Fe-Ti oxide equilibria suggest temperatures of ~ 765 °C and oxygen fugacities of NNO + 1.5. Melt inclusions indicate that magma representing the stratigraphically lowest lithology was crystallizing at ~ 260 MPa with a contemporary mixed H2O-CO2 fluid phase becoming progressively more H2O-rich. Magma forming the other lithologies crystallized in the presence of this H2O-dominated fluid, as demonstrated by the presence of cummingtonite and little to no CO2 in melt inclusions. Amphibole and quartz-feldspar-melt equilibria models yield results indicating a range of crystallization pressures from ~ 400 MPa to ~ 175 MPa. Apatites and melt inclusions have lower chlorine contents than more recently erupted material at Augustine suggesting that the composition of Augustine's volatile phase has changed over time. Reheating textures in melt inclusions and phenocrysts, as well as the presence of xenocrysts of olivine and clinopyroxene containing mafic melt inclusions, signify the likelihood of mixing and/or mingling of magmas as an eruption trigger. The unique qualities of this Pleistocene rhyolite and the potential hazard of a similarly large eruption in modern times indicate that further study is warranted.

  19. Facilitating Research and Learning in Petrology and Geochemistry through Classroom Applications of Remotely Operable Research Instrumentation

    Science.gov (United States)

    Ryan, J. G.

    2012-12-01

    Bringing the use of cutting-edge research tools into student classroom experiences has long been a popular educational strategy in the geosciences and other STEM disciplines. The NSF CCLI and TUES programs have funded a large number of projects that placed research-grade instrumentation at educational institutions for instructional use and use in supporting undergraduate research activities. While student and faculty response to these activities has largely been positive, a range of challenges exist related to their educational effectiveness. Many of the obstacles these approaches have faced relate to "scaling up" of research mentoring experiences (e.g., providing training and time for use for an entire classroom of students, as opposed to one or two), and to time tradeoffs associated with providing technical training for effective instrument use versus course content coverage. The biggest challenge has often been simple logistics: a single instrument, housed in a different space, is difficult to integrate effectively into instructional activities. My CCLI-funded project sought primarily to knock down the logistical obstacles to research instrument use by taking advantage of remote instrument operation technologies, which allow the in-classroom use of networked analytical tools. Remote use of electron microprobe and SEM instruments of the Florida Center for Analytical Electron Microscopy (FCAEM) in Miami, FL was integrated into two geoscience courses at USF in Tampa, FL. Remote operation permitted the development of whole-class laboratory exercises to familiarize students with the tools, their function, and their capabilities; and it allowed students to collect high-quality chemical and image data on their own prepared samples in the classroom during laboratory periods. These activities improve student engagement in the course, appear to improve learning of key concepts in mineralogy and petrology, and have led to students pursuing independent research projects, as

  20. Petrology And Geochemistry Of Barite Mineralisation Around Azara North Central Nigeria

    Directory of Open Access Journals (Sweden)

    Tanko

    2015-05-01

    Full Text Available ABSTRACT The Azara barite deposits formed parts of Middle Benue Trough which is located in an elongated rift or faulted-bounded mega structural depression trending NE-SW to a length of over 1000 km and a width of 100 km.Petrological and geochemical investigations of Azrara barite deposits were carried out. Eight 8 selected samples of barites were collected from the veins four from known veins V1V3V17 and V 18 and four from new veins VAVBVCand VD werecarried out with the aim of determining their mineralisation potentials using petrographic studies and gravimetric method of analyses. The Petrographic studies of some of the thin section of the samples conducted using a polarizing microscope to determine the contents distributions and textures of the various veins Table 1. The weight percentage composition of barite in the samples are V1 86.39 VC82.61 V1881.48 V3 81.17 V17 79.82 VA78.94 VB76.82 and VD 70.55 respectively. It is deduced from this work that the chemical weathering of the carbonates resulted in two distinct types of barites Barite associated with mainly quartz SiO2 and limonite FeOOH.nH2O as major gangue and barite with siderite Ferrous Carbonate with high amount of Mg ankerite Ca Fe Mg CO3 and Calcite CaCO3. The outcomes were compared with the barite specification of Weigal1937 of 95.00 and were found to be good for making drilling mud for use in the oil industry paints and other chemicals

  1. Petrology and Bulk Chemistry of Modern Bed Load Sediments From Rivers Draining the Eastern Tibetan Plateau

    Science.gov (United States)

    Borges, J. B.

    2003-12-01

    We studied river bed load petrology and bulk sediment chemistry of the headwaters of the Changjiang, Huang He and Red rivers in China and Vietnam. These rivers drain the eastern and southeastern parts of the Tibetan Plateau which includes part of the Indian-Eurasian suture zone. The eastern Tibetan Plateau is dominated by marine sedimentary rocks with a few scattered intrusive igneous outcrops, while the suture zone is characterized by a mixture of high-grade metamorphic, ultramafic, granitic, volcanic arc and marine sedimentary rocks. The arithmetic average for Qt: Ft: Rft along the suture zone varies from 56:2:42 along the Red River Fault (RRF) zone to 38:6:56 in the interior of the continent, while sands from rivers draining the plateau average 32:8:60. The sands analyzed in this study are relatively immature compared to most data available from most rivers in the tropics. The average Chemical Index of Alteration (CIA) for samples from the RRF suture zone (0.62) is similar to that of rivers draining other tropical regions like the Niger, Chao Phraya, Mekong, Ganges, Amazon and Brahmaputra. The CIA values from the RRF zone are also significantly different from the rest of the suture zone (0.36) and the plateau area (0.38). The difference can be attributed to the combined effect of relief and precipitation. The RRF lies in the Red River drainage and receives ˜1820 mm of precipitation annually, while the plateau area averages ˜620 mm annually. In the case of the Red River drainage, the relief combined with higher humidity can increase physical weathering and reduce the residence time of sediment in the river drainage, therefore, continuously replacing the sediment transported out of the drainage by freshly weathered immature materials. In the plateau area, lower precipitation and runoff may limit sediment transport and chemical weathering leading to sediment immaturity.

  2. New insights on the petrology of submarine volcanics from the Western Pontine Archipelago (Tyrrhenian Sea, Italy)

    Science.gov (United States)

    Conte, A. M.; Perinelli, C.; Bianchini, G.; Natali, C.; Martorelli, E.; Chiocci, F. L.

    2016-11-01

    The Pontine Islands form a volcanic archipelago in the Tyrrhenian Sea. It consists of two edifices, the islands of Ponza, Palmarola and Zannone and the islands of Ventotene and Santo Stefano, respectively. The Archipelago developed during two main volcanic cycles in the Plio-Pleistocene: 1) the Pliocene episode erupted subalkaline, silica-rich volcanic units, which constitute the dominant products in the western edifice (Ponza and Zannone Islands); 2) the Pleistocene episode erupted more alkaline products, represented by evolved rocks (trachytes to peralkaline rhyolites) in the islands of Ponza and Palmarola and by basic to intermediate rocks in the eastern edifice (Ventotene and Santo Stefano Islands). In this paper we present new geochemical and petrological data from submarine rock samples collected in two oceanographic cruises and a scuba diving survey. The main result is the recovery of relatively undifferentiated lithotypes that provide further insights on the magmatic spectrum existing in the Pontine Archipelago, allowing modelling of the whole suite of rocks by fractional crystallization processes. New major and trace element data and thermodynamic constrains (by the software PELE) indicate the existence of three distinct evolutionary trends corresponding to a HK calcalkaline series in the Pliocene, followed by a transitional and then by a shoshonite series in the Pleistocene. In particular, the transitional series, so far overlooked in the literature, is required in order to explain the genesis of several peralkaline felsic rocks recognized in the Archipelago. On the whole, the new geochemical data i) confirm the orogenic signature of the suites, ii) allow to rule out an anatectic origin for both subalkaline and peralkaline rhyolites and iii) indicate highly heterogeneous mantle sources, due to crustal components variously recycled in the mantle via subduction.

  3. A new petrological and geophysical investigation of the present-day plumbing system of Mount Vesuvius

    Science.gov (United States)

    Pommier, A.; Tarits, P.; Hautot, S.; Pichavant, M.; Scaillet, B.; Gaillard, F.

    2010-07-01

    A model of the electrical resistivity of Mt. Vesuvius has been elaborated to investigate the present structure of the volcanic edifice. The model is based on electrical conductivity measurements in the laboratory, on geophysical information, in particular, magnetotelluric (MT) data, and on petrological and geochemical constraints. Both 1-D and 3-D simulations explored the effect of depth, volume and resistivity of either one or two reservoirs in the structure. For each configuration tested, modeled MT transfer functions were compared to field transfer functions from field magnetotelluric studies. The field electrical data are reproduced with a shallow and very conductive layer (˜0.5 km depth, 1.2 km thick, 5 ohm.m resistive) that most likely corresponds to a saline brine present beneath the volcano. Our results are also compatible with the presence of cooling magma batches at shallow depths ( ˜100 ohm.m. According to a petro-physical conductivity model, such a resistivity value is in agreement either with a low-temperature, crystal-rich magma chamber or with a small quantity of hotter magma interconnected in the resistive surrounding carbonates. However, the low quality of MT field data at long periods prevent from placing strong constraints on a potential deep magma reservoir. A comparison with seismic velocity values tends to support the second hypothesis. Our findings would be consistent with a deep structure (8-10 km depth) made of a tephriphonolitic magma at 1000°C, containing 3.5 wt%H2O, 30 vol.% crystals, and interconnected in carbonates in proportions ˜45% melt -55% carbonates.

  4. Palacio Real de Madrid: La Petrología al Servicio del Patrimonio Arquitectónico

    OpenAIRE

    2008-01-01

    52 páginas.-- Comunicación presentada en el curso: "La Petrología al Servicio del Patrimonio Arquitectónico". 1ª Edición. Organizado por el Instituto de Geología Económica (IGE), la Escuela Superior de Conservación de Bienes Culturales (ESCRBC) y el programa MATERNAS de Conservación del Patrimonio (IV PRICIT-CAM). Curso realizado los días 18, 19, 25 y 26 Abril de 2008, en la Escuela Superior de Conservación.-- Se incluye tríptico del curso.

  5. The origin and tectonic setting of precambrian greywacke of Ribandar-Chimbel, Goa, India: Petrological and geochemical evidence

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, G.Q.; Iyer, S.D.; Kotha, M.

    of their sedimentary basins are interrelated (Bhatia, 1983; Crook, 1974; Schwab, 1975; Potter 1978; Dickinson and Suczek 1979; Dickinson, and Valloni, 1980; Valloni, and Maynard 1981). The greywacke composition is also used to decipher the origin and tectonic..., 133: 111-125. Pettijohn, F.J., Potter, P.E., Siever, R., 1972. Sand and sandstone. Springer-Verlag, New York pp 618. Potter, P.E., 1978. Petrology and chemistry of modern big river sands. Journal of Geology, 86: 423-449. Rashid, S.A., 2005...

  6. Petrological and Sr-Nd-Os isotopic constraints on the origin of the Fanshan ultrapotassic complex from the North China Craton

    Science.gov (United States)

    Niu, Xiaolu; Chen, Bin; Liu, Ankun; Suzuki, K.; Ma, Xu

    2012-09-01

    The Fanshan ultramafic-syenitic complex is located on the northern margin of North China Craton, with zircon U-Pb ages of 220 Ma. It is a concentrically zoned complex, with syenite in the core, surrounded by ultramafic rocks (clinopyroxenite, glimmerite) and garnet-clinopyroxene syenite, respectively, towards the rim. Diopside, biotite, orthoclase, melanite, magnetite and apatite are the major minerals, with subordinate sphene and calcite. Mineralogy, petrology and geochemical studies point to the formation of the complex through fractional crystallization and accumulation from a SiO2-undersaturated ultrapotassic alkaline-peralkaline parent magma that is characterized by high CaO, Fe2O3, K2O and fluid compositions (P2O5, CO2, H2O, F), and by high temperature and high oxygen fugacity. Rocks from the complex are highly enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE; e.g., Rb, Ba, Sr), depleted in high field strength elements (HFSE; e.g., Nb, Ta, Ti), and show relatively homogeneous Sr-Nd isotopic compositions with initial 87Sr/86Sr = 0.70513-0.70597 and ɛNd(t) = - 5.8 to - 5.3. The data suggest that the Fanshan complex originated from a phlogopite-clinopyroxenite-rich lithosphere mantle source that had previously been metasomatized by melts from carbonated oceanic crust above a subduction zone. Highly radiogenic Os isotope compositions (initial 187Os/188Os = 0.299-2.449) suggest that the parent magma to the Fanshan complex has been contaminated by Precambrian mafic crustal rocks during magma emplacement in crustal levels. The occurrence of the Fanshan complex, together with many other ultramafic/alkaline plutons of similar ages, on the northern margin of the North China Craton suggests that the northern margin of the craton entered into a large-scale extensional regime in late Triassic after the final amalgamation between Mongolian microcontinent and the craton.

  7. East of Eden / M. A.

    Index Scriptorium Estoniae

    M. A.

    2005-01-01

    Palmses toimub sel nädalal rahvusvahelise stsenaariumikoolituse East of Eden seminar. Koolituse koordinatsioonikeskus tegutseb alates 2005.aastast Eesti Filmi Sihtasutuse juures, Eesti--poolseks koordinaatoriks Anu Ernits

  8. Discourse Between East and West

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The first Chinese-hosted cultural dialogue between the East and the West was held in Nishan, Shandong Province The first Nishan Forum on World Civilizations kicked off on September 26 at Nishan Mountain, 25 km southeast

  9. East of Eden / M. A.

    Index Scriptorium Estoniae

    M. A.

    2005-01-01

    Palmses toimub sel nädalal rahvusvahelise stsenaariumikoolituse East of Eden seminar. Koolituse koordinatsioonikeskus tegutseb alates 2005.aastast Eesti Filmi Sihtasutuse juures, Eesti--poolseks koordinaatoriks Anu Ernits

  10. East India Company Logbooks - Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This collection consists of images of 1,235 ship logbooks created during British East India Company voyages. Period of record 1786-1834, peaking in 1804. The...

  11. Formation and preservation of biotite-rich microdomains in high-temperature rocks from the Antananarivo Block, Madagascar

    Science.gov (United States)

    Cenki-Tok, Bénédicte; Berger, Alfons; Gueydan, Frédéric

    2016-07-01

    Highly restitic rocks from the Antananarivo Block in northern Madagascar are investigated in this study in order to unravel processes of H2O-rich biotite formation in HT rocks. Polyphase metamorphism and melt migration occurred at 0.6 GPa and 850 °C. Biotite remains stable together with orthopyroxene and makes up to 45 vol% of the rock. In addition, three well-characterised and delimited microdomains having different textural, chemical and petrological characteristics are preserved. Thermodynamic models using the specific bulk compositions of the domains are in agreement with petrological observations. These rocks provide evidence that the lower crust may be strongly heterogeneous, locally associated to the formation of hydrous restites controlled by episodes of melt production and melt escape. This has significant consequences for understanding of the lower crust.

  12. JPRS Report, East Europe.

    Science.gov (United States)

    2007-11-02

    accused of having caused, by negligent judgement , the collision of two aircraft in which more than 170 people died. The entire world public and press...The application of the most recent scientific knowledge and methods, said Prof Thielmann, must be combined with human warmth and a spirit of...formation and consolidation of norms relating to psy- chosocial, interpersonal behavior that are in keeping with the humanistic requirements of a

  13. Regions. [Africa, Middle East].

    Science.gov (United States)

    1985-03-01

    This discussion of population focuses on the regions of Africa and the Middle East. In South Africa more white women are working but fewer black women work. The overall result is that the percentage of women who work is declining. Marita de Beer, research liaison executive at the South African Advertising Research Foundation, reports that the female population grew by 31% in the past 10 years while the number of working women has grown by only 11%. Among blacks the female population rose by 36%, but the number of workers among them declined by about 1%. Married women are among the fastest growing groups of working women in South Africa. The most recent estimate of the population of Nigeria is 92 million. According to Professor Vremudia Diejomaoh, Nigeria's population will probably reach 155 million by 2000 with 33% living in urban areas. In Saudi Arabia the Pan Arab Research Center recently completed a census of retail outlets in 3 metropolitan areas: Jeddah, Riyadh, and Dammam. The types of outlets surveyed include large supermarkets, small supermarkets, groceries with and without deep freeze, tobacco shops, meat shop/delis, small cafeterias, large restaurants/hotels, cosmetics shops or perfumeries, camera stores, toy shops, pharmacies, watch and gift shop, newsstands, department store, and appliance outlets. Using the Census of Retail Outlets as a base, Pan Arab Research Center also has a new distribution audit system that will cover 500 outlets. By plotting Arab countries according to their population policies and their current growth rates, it is possible to project where the middle class will grow fastest in the Arab world. The countries that have declining growth rates and strong population programs designed to encourage lower fertility rates among women are Egypt, Tunisia, Morocco, Algeria, and Lebanon. The countries most likely to have a better per capita distribution of resources within this decade are those where governments encourage reductions in

  14. Investigation on type and origin of iron mineralization at Mesgar occurrence, south of Zanjan, using petrological, mineralogical and geochemical data

    Directory of Open Access Journals (Sweden)

    Mohammad Ebrahimi

    2015-04-01

    rock-fluid interaction in Mesgar. Comparison of the geological, mineralogical, geochemical, textural and structural characteristics of the Mesgar occurrence with different types of iron deposits reveals that iron mineralization at Mesgar is originally formed as volcano-sedimentary, and then reconcentrated as vein mineralization by hydrothermal fluids (Barker, 1995; Marschik and Fontbote, 2001, Shahidi et al., 2012. Acknowledgements The authors are grateful to the University of Zanjan Grant Commission for research funding. Journal of Economic Geology reviewers and editor are also thanked for their constructive suggestions on alterations to the manuscript. References Barker, D.S., 1995. Crystallization and alteration of quartz monzonite, Iron Spring mining district, Utah, relation to associated iron deposits. Economic Geology, 90 (8: 2197–2217. Chappell, B.W. and White, A.J.R., 1974. Two contrasting granite types. Pacific Geology, 8(2: 173–174. Harris, N.B.W., Pearce, J.A. and Tindle, A.G., 1986. Geochemical characteristics of collision-zone magmatism. In: M.P. Coward, and A.C. Ries (Editors, Collision Tectonics. Geological Society of London, Special Publication, pp. 67–81. Kuster, D. and Harms, U., 1998. Post-collisional potassic granitoids from the southern and northern parts of the Late Neoproterozoic East Africa Orogen: a review. Lithos, 45(1: 177–195. Marschik, R. and Fontbote, L., 2001. The Candelaria-Punta Del Cobre iron oxide Cu-Au (-Zn-Ag deposits, Chile. Economic Geology, 96(8: 1799–1826. Miyashiro, A., 1977. Nature of alkalic volcanic series. Contributions to Mineralogy and Petrology, 66(1: 91–110. Rādfar, J., Mohammadiha, K. and Ghahraeipour, M., 2005. Geological map of Zarrin Rood (Garmab, scale 1:100,000. Geological Survey of Iran. Shahidi, E., Ebrahimi, M. and Kouhestani, H., 2012. Structure, texture and mineralography of Mesgar iron occurrence, south Gheydar. 4th Symposium of Iranian Society of Economic Geology, University of Birjand, Birjand

  15. Regionalism in East Asia: The Role of North East Asian Nations

    Directory of Open Access Journals (Sweden)

    Fithra F. Hastiadi

    2011-01-01

    Full Text Available Problem statement: For the past few years, regionalism has been progressing in East Asia with the likes of China, Japan and Korea (CJK as the most prominent actors. Unfortunately, with the absence of trade arrangement amongst the CJK, the present regional trade scheme is not sufficient to reach sustainability. Thus, the study aims to give the solution to the problem. This study found the inefficient trade scheme through Engle-Granger Cointegration and Error Correction Mechanism. Two Stage Least Squares in a static panel fixed effect model were also employed to proof the spill-over effect. Conclusion/Recommendations: The study underlines the importance of triangular trade agreement for accelerating the phase of growth in CJK which eventually created a spillover effect to East Asia as a whole. Moreover, the study argued that the spillover effect would function as an impetus for creating region-wide FTA. Furthermore, the study also identified a number of economic and political factors that can support the formation of East Asian Regionalism.

  16. Petrology of gabbroic xenoliths in 1960 Kilauea basalt: crystalline remnants of prior (1955) magmatism

    Science.gov (United States)

    Fodor, R.V.; Moore, R.B.

    1994-01-01

    The 1960 Kapoho lavas of Kilauea's east rift zone contain 1-10 cm xenoliths of olivine gabbro, olivine gabbro-norite, and gabbro norite. Textures are poikilitic (ol+sp+cpx in pl) and intergranular (cpx+pl??ol??opx). Poikilitic xenoliths, which we interpret as cumulates, have the most primitive mineral compositions, Fo82.5, cpx Mg# 86.5, and An80.5. Many granular xenoliths (ol and noritic gabbro) contain abundant vesicular glass that gives them intersertal, hyaloophitic, and overall 'open' textures to suggest that they represent 'mush' and 'crust' of a magma crystallization environment. Their phase compositions are more evolved (Fo80-70, cpx Mg# 82-75, and An73-63) than those of the poikilitic xenoliths. Associated glass is basaltic, but evolved (MgO 5 wt%; TiO2 3.7-5.8 wt%). The gabbroic xenolith mineral compositions fit existing fractional crystallization models that relate the origins of various Kilauea lavas to one another. FeO/MgO crystal-liquid partitioning is consistent with the poikilitic ol-gabbro assemblage forming as a crystallization product from Kilauea summit magma with ???8 wt% MgO that was parental to evolved lavas on the east rift zone. For example, least squares calculations link summit magmas to early 1955 rift-zone lavas (???5 wt% MgO) through ???28-34% crystallization of the ol+sp+cpx+pl that comprise the poikilitic ol-gabbros. The other ol-gabbro assemblages and the olivine gabbro-norite assemblages crystallized from evolved liquids, such as represented by the early 1955 and late 1955 lavas (???6.5 wt% MgO) of the east rift zone. The eruption of 1960 Kapoho magmas, then, scoured the rift-zone reservoir system to entrain portions of cumulate and solidification zones that had coated reservoir margins during crystallization of prior east rift-zone magmas. ?? 1994 Springer-Verlag.

  17. Lithospheric analysis of satellite geopotential anomalies of East Asia

    Science.gov (United States)

    Tan, Li

    Satellite gravity and magnetic anomalies are used to study the lithosphere of East Asia. Free-air gravity anomalies are decomposed into terrain-correlated, mantle/core and intracrustal components by spectral correlation analysis of the free-air gravity anomalies and terrain gravity effects. Compensated terrain gravity anomalies are obtained by removing the terrain-correlated free-air gravity anomalies. They are used to estimate the Moho undulation and crustal thickness by Gauss-Legendre quadrature (GLQ) inversion techniques assuming a Airy-Heiskanen model of crustal compensation. These results are used to develop enhanced reduction procedures to generate an improved Magsat magnetic anomaly map for East Asia. A degree 12 core field is removed from the data that are updated for the crustal components in the core field differences between degree 14 and 12. These components are estimated by using spectral correlation analysis to compare the Magsat anomalies to the magnetic effect of the crust that is available from the first vertical derivative of the terrain-correlated free-air gravity anomalies via Poisson's theorem. External field effects are separated using pass-by-pass correlation analysis of the dusk and dawn data sets and their spectral reconstruction. Coherent components in the dusk and dawn maps are combined to estimate the magnetic anomalies of the lithosphere. Long wavelength magnetic features related to lower crustal thickness variations are converted into effective magnetization contrasts by a new GLQ inversion technique. Effective magnetization contrasts of the lower crust range over ±4 A/m in accordance petrological studies. Finally, a new GLQ integration formula for triangular wedge sources is derived for modeling of satellite-altitude geopotential field anomalies from arbitrarily shaped sources. Detailed magnetization and density contrasts for central India, the Tibetan Plateau, and the Bengal Gulf region are modeled by this new formula. Positive

  18. A seismological and petrological crustal model for the southwest of the Sierra de Pie de Palo, province of San Juan

    Directory of Open Access Journals (Sweden)

    Brígida Castro de Machuca

    2012-06-01

    Full Text Available A seismic velocity analysis from teleseismic receiver functions recorded in the southwestern fank of the Sierra de Pie de Palo (Western Sierras Pampeanas, Argentina, is compared with seismic properties directly calculated from lithological composition. The seismological results show an upper layer located in the first 13 km depth. A deeper contrast in seismic velocities is found at a depth of 28 km; the petrological results indicate a composition compatible with observed greenschist and amphibolite facies mafic rocks up to this depth. The receiver function measurements at 13 km and 28 km depths could be interpreted as two potential décollement levels that might have favoring a mechanism to thicken the whole crust, which produces a receiver function Moho signal located at 47 km depth. In addition, the lower crust between 28 km and 47 km exhibits high seismic P-wave velocities and Vp/Vs ratio (> 1.80 that are representative of a densification consistent with upper amphibolite to granulite/ecoglite facies lithologies. Based on these results, the combined petrological and seismological analyses suggest the continuation of the same mafic-crust outcropping lithologies into the lower levels of the 47-km thickened crust, which could be part of the Pie de Palo Complex ophiolite belt or the Precordillera basement.

  19. Garnet Signatures in Geophysical and Geochemical Observations: Insights into the Thermo-Petrological Structure of Oceanic Upper Mantle

    Science.gov (United States)

    Grose, C. J.; Afonso, J. C.

    2013-12-01

    We have developed new physically comprehensive thermal plate models of the oceanic lithosphere which incorporate temperature- and pressure-dependent heat transport properties and thermal expansivity, melting beneath ridges, hydrothermal circulation near ridge axes, and insulating oceanic crust. These models provide good fits to global databases of seafloor topography and heat flow, and seismic evidence of thermal structure near ridge axes. We couple these thermal plate models with thermodynamic models to predict the petrology of oceanic lithosphere. Geoid height predictions from our models suggest that there is a strong anomaly in geoid slope (over age) above ~25 Ma lithosphere due to the topography of garnet-field mantle. A similar anomaly is also present in geoid data over fracture zones. In addition, we show that a new assessment of a large database of ocean island basalt Sm/Yb systematics indicates that there is an unmistakable step-like increase in Sm/Yb values around 15-20 Ma, indicating the presence of garnet. To explain this feature, we have attempted to couple our thermo-petrological models of oceanic upper mantle with an open system, non-modal, dynamic melting model with diffusion kinetics to investigate trace element partitioning in an ascending mantle column.

  20. Coupled Petrological and Geodynamic Models of Mantle Flow in Subduction Zones; the Importance of Chlorite in the Emergence of a Low-Viscosity Channel

    Science.gov (United States)

    Smith, P. M.; Baker, L. J.; Asimow, P. D.; Gurnis, M. C.

    2007-12-01

    Seismic velocity and attenuation studies have shown that 5-20 km thick low velocity layers exist above seismically fast slabs and are associated with broad zones of high attenuation in many subduction zones. These observations are generally interpreted as formation of hydrous phases by dehydration of the slab, although the impact of water in nominally anhydrous minerals (NAM) on seismic wave propagation is largely unknown. Recent petrological experiments on hydrous peridotite at subduction zone conditions suggest that chlorite will be stable adjacent to the subducting slab in sufficient quantities to be a significant water sink. We use a scheme that couples a petrological model (pHMELTS) with a 2-D thermal and variable viscosity flow model (ConMan) to model energy and mass transfer within a subduction zone. By varying input parameters including the convergence rate and slab dip we have developed models for cases in the Costa-Rica and Izu- Bonin-Marianas arc systems and are able to predict major and trace element compositions of primary melts, as well as geophysical observables, such as the topography and geoid. We find that the emergence of a slab- adjacent low-viscosity channel (LVC) is a natural consequence of the thermal and chemical controls on mantle dynamics and feedback between them. In our earlier models, as the LVC is dragged downwards by the subducting slab, hornblende breaks down at about 2.5 GPa and other hydrous phases such as serpentine are secondary in importance to the NAM water reservoir. The spatial limit of the LVC is the water-saturated solidus of the hydrated peridotite; the LVC thickens as the peridotite is progressively depleted by melting and the solidus migrates into the warmer wedge, despite water replenishment at depth. pHMELTS is a hybrid of the pMELTS model of Ghiorso and co-workers and includes amphiboles, serpentines and micas. Chlorite was lacking but we have recently rectified this omission. Following De Capitani and co- workers, we

  1. Petrology of HP metamorphic veins in coesite-bearing eclogite from western Tianshan, China: Fluid processes and elemental mobility during exhumation in a cold subduction zone

    Science.gov (United States)

    Lü, Zeng; Zhang, Lifei; Du, Jinxue; Yang, Xin; Tian, Zuolin; Xia, Bin

    2012-04-01

    A petrological study was carried out for high pressure (HP) veins which cut through the host coesite-bearing eclogites at Habutengsu-Kebuerte in western Tianshan, China. The results place constraints on the origin and property of metamorphic fluids during subduction-zone metamorphism. Omphacite-, clinozoisite- and quartz-dominated veins occur on centimeter to meter scales within lens-shaped and layered eclogites, or cutting into the country rocks of garnet phengite schists. Coesite-bearing eclogites mainly consist of fibrous fine-grained omphacite and porphyroblastic garnet, with minor amounts of amphibole (mainly barroisite), clinozoisite, white mica (mainly paragonite) and rutile. The veins are pronouncedly coarse-grained compared to the host eclogites and commonly consist of quartz, clinozosite, rutile, white mica (phengite and paragonite) and garnet, with or without omphacite, titanite, apatite, carbonate (mainly dolomite) and glaucophane. Fluid inclusions are abundant in vein omphacite, titanite and apatite, but are rare in the equivalent minerals of host eclogites. Rounded vein garnets usually occur close to the sharp interface of vein and host eclogite. Omphacite in the veins is characterized by its euhedral form surrounded by quartz, or coarse bladed aggregates in contrast to the fibrous or patchy one, suggesting dynamic recrystallization in the host rocks. Omphacite in both veins and host eclogites has similar jadeite contents (Jd40-50), indicating formation at eclogite-facies metamorphic conditions. Vein phengite uniformly contains certain amounts of Ba with maximum BaO content of 3.16-4.25 wt.%, suggesting that Ba was mobilized during the exhumation of UHP rocks. Specific textures of vein minerals, such as the enclosure of magnesite (or calcite) in dolomite, rutile in titanite, and the occurrence of zoned Ba-rich phengite, indicate the chemical variability of channelized fluids over time. Based on Zr content in rutile and the presence of paragonite

  2. Petrological mapping of Volcanic Plumbing Systems using amphiboles in mixed intermediate magmas

    Science.gov (United States)

    Kiss, Balázs; Harangi, SzZabolcs; Hauzenberger, Christoph; Ntaflos, Theodoros; Mason, Paul R. D.

    2016-04-01

    Petrological mapping of volcanic plumbing systems (VPS) is essential to understand the magma evolution and to interpret geophysical signals of monitored volcanoes. The mapping includes the determination of the compositions of magmas feed the system and their storage depths. Intermediate magmas are usually formed by magma mixing a processes that mask the real compositional variation of magmas feed the VPS. However phenocrysts can preserve this information in their chemical stratigraphy. Amphibole can be a powerful tool in these studies because it can incorporate petrogenetically important trace elements primarily controlled by the coexisting melt composition, additionally the major element composition can be used to calculate pressure. We studied the zoning, texture and major and trace element composition of amphiboles from the Ciomadul, a late pleistocen dacite volcano. The erupted dacites contain abundant amphibole phenocrysts. Amphibole coexist with all of the rock forming minerals (e.g. with quartz or with olivine) indicating their diverse origin. The amphiboles show large major element compositional variation (e.g. Al2O3: 6-15 wt%) accompanied with large variation in trace element (e.g. Cr: 10-3000 ppm, Sr: 55-855 ppm, Eu/Eu*: 0.62-1.19) even in a single sample or single crystal and they represent antecryst (reworked) and phenocryst (in situ crystallized) populations. Such a large compositional variation of amphiboles is commonly observed at andesite-dacite arc volcanoes. Hornblendes (antecryst1) have low Al, Mg/Fe, and negative Eu-anomaly; they equilibrated with rhyolitic melt at near-solidus temperature. Antecryst2 is represented by Cr-, Mg-rich amphiboles; they can contain Cr-spinel inclusions suggesting near-liquidus crystallization from primitive mafic melts. Phenocrysts show large compositional variation sample by sample that is different from the antecrysts suggesting variable pre-eruptive conditions. The antecrysts are derived from a stratified (mafic

  3. Quaternary Basanitic Rocks within the Eastern Anatolian Volcanism (Turkey): Petrological and Geochemical Constrains

    Science.gov (United States)

    Özdemir, Yavuz; Mercan, Çaǧrı; Oyan, Vural; Atakul-Özdemir, Ayşe

    2017-04-01

    The Eastern Anatolian Cenozoic continental intraplate volcanism was initiated in Middle Miocene as a result of the convergence between the Arabian and Anatolian plates. The origin of Eastern Anatolian volcanism has been the focus of many petrological studies that have aimed to resolve the relative contributions of asthenospheric mantle and/or lithospheric mantle with/without subduction component in the genesis of magmas that compositionally have many affinities to ocean island basalts (OIB) and volcanic arcs. Volcanism in the region characterized by mainly stratovolcanoes, basaltic lava plateaus and are dominantly spread at the northern parts of Bitlis Pötürge Massif (BPM). Our study focuses on a small scale Quaternary basaltic system that firstly observed within the BPM. The volcanic rocks of our study located 50 km to the south of Lake Van and are basanitic in composition. They exposed along K-G striking tensional fissures and crosscut the Upper unit of the Bitlis Massif. Initial products of the volcanism are scoria fall deposits. Thick basanitic lava flows overly the pyroclastics and formed columnar structures. The basanites are generally fine-grained with phenocrysts of olivine+clinopyroxene. The groundmass is typically of clinopyroxene, olivine and Ti magnetite and Cr spinel with interstitial nepheline. The olivine phenocrysts are typically euhedral to subhedral with Forsterite contents of Fo73-83. Clinopyroxenes are highly calcic and show modest variations in Wo47-52-En34-42-Fs10-15 and are weakly zoned with mg# 89-87 at cores to 86-84 at rims. Nephelines occur as minor minerals within the networks of other groundmass minerals. Ti rich and Fe-Cr spinels occur as inclusions in olivine and clinopyroxenes as well as within the groundmass. LILE and LREE enrichments over HFSE and HREE suggest similarities with magmas generated from enriched mantle sources. EC-AFC modeling of trace element and isotope compositions indicates that assimilation of crustal

  4. The petrology and geochemistry of Gharyan volcanic province of NW Libya

    Science.gov (United States)

    Al-Hafdh, N. M.; Gafeer, A. S.

    2015-04-01

    Gharyan Volcanic Province (GVP) is one of the four major outpouring volcanic provinces (Jabal as Sawda, Jabal Al Haruj, and Jabal Nuqay) in Libya. It culminates the extreme NNW-SSE linear trend with the other province which defines a systematic decrease in age from NWW to SSE. The voluminous petrologic and chronologic episode in GVP is the Old Lava Series (OLS). This OLS (55-50 Ma) is flown over 1000 km of Mesozoic rocks that are sliced by Wadi Ghan fault zone. The second cycle is represented by the phonolite-trachyte intrusions (40 Ma). Those intrusions occur in the form of laccoliths and plugs where Wadi Ghan fault zone has a conspicuous effect in their emplacement behavior. The Late Volcanic Center (LVC) is the main young volcanic activity in the province (<12 Ma). They show different mode of eruptions on the continuous plateau of OLS. Young Lava Series (YLS) are minor eruptions that have a distinctive appearance on the field and landsat image by occupying an ancient buried wadies. The compound phonolite laccoliths in Garyat Gamatat al-Gharyiha area increase in relief northwardly due to the imparity of denudation with the OLS flows at the southern portions of the area. One of those phonolite samples shows a crustal contamination due to its anomalous in Sr content. The radial pattern of OLS flows in urban area has some differentiation degree by their relative evolution from basalts to basaltic andesites. The chemistry of LVC in the same area does not show close concordance with the LVC basanitic suite of Busrewil and Wadsworth (1980). On other hand, the basaltic sill in Garyat Gamatat al-Gharyiha area is belonging to the LVC activity in GVP by their concordant with the geochemistry of LVC basanitic phase. The ultrabasic rocks in the investigated areas are four-phase lherzolite (olivine + orthopyroxene + clinopyroxene + spinel) restrict only in LVC phase as sub-rounded nodules. These xenoliths penetrate the whole crust with relatively large velocity by melts with

  5. Petrology, Palynology, and Geochemistry of Gray Hawk Coal (Early Pennsylvanian, Langsettian in Eastern Kentucky, USA

    Directory of Open Access Journals (Sweden)

    James C. Hower

    2015-09-01

    Full Text Available This study presents recently collected data examining the organic petrology, palynology, mineralogy and geochemistry of the Gray Hawk coal bed. From the Early Pennsylvanian, Langsettian substage, Gray Hawk coal has been mined near the western edge of the eastern Kentucky portion of the Central Appalachian coalfield. While the coal is thin, rarely more than 0.5-m thick, it has a low-ash yield and a low-S content, making it an important local resource. The Gray Hawk coal palynology is dominated by Lycospora spp., and contains a diverse spectrum of small lycopods, tree ferns, small ferns, calamites, and gymnosperms. The maceral assemblages show an abundance of collotelinite, telinite, vitrodetrinite, fusinite, and semifusinite. Fecal pellet-derived macrinite, albeit with more compaction than is typically seen in younger coals, was observed in the Gray Hawk coal. The minerals in the coal are dominated by clay minerals (e.g., kaolinite, mixed-layer illite/smectite, illite, and to a lesser extent, pyrite, quartz, and iron III hydroxyl-sulfate, along with traces of chlorite, and in some cases, jarosite, szomolnokite, anatase, and calcite. The clay minerals are of authigenic and detrital origins. The occurrence of anatase as cell-fillings also indicates an authigenic origin. With the exception of Ge and As, which are slightly enriched in the coals, the concentrations of other trace elements are either close to or much lower than the averages for world hard coals. Arsenic and Hg are also enriched in the top bench of the coal and probably occur in pyrite. The elemental associations (e.g., Al2O3/TiO2, Cr/Th-Sc/Th indicate a sediment-source region with intermediate and felsic compositions. Rare metals, including Ga, rare earth elements and Ge, are highly enriched in the coal ashes, and the Gray Hawk coals have a great potential for industrial use of these metals. The rare earth elements in the samples are weakly fractionated or are characterized by heavy

  6. 3D Integrated geophysical-petrological modelling of the Iranian lithosphere

    Science.gov (United States)

    Mousavi, Naeim; Ardestani, Vahid E.; Ebbing, Jörg; Fullea, Javier

    2016-04-01

    The present-day Iranian Plateau is the result of complex tectonic processes associated with the Arabia-Eurasia Plate convergence at a lithospheric scale. In spite of previous mostly 2D geophysical studies, fundamental questions regarding the deep lithospheric and sub-lithospheric structure beneath Iran remain open. A robust 3D model of the thermochemical lithospheric structure in Iran is an important step toward a better understanding of the geological history and tectonic events in the area. Here, we apply a combined geophysical-petrological methodology (LitMod3D) to investigate the present-day thermal and compositional structure in the crust and upper mantle beneath the Arabia-Eurasia collision zone using a comprehensive variety of constraining data: elevation, surface heat flow, gravity potential fields, satellite gravity gradients, xenoliths and seismic tomography. Different mantle compositions were tested in our model based on local xenolith samples and global data base averages for different tectonothermal ages. A uniform mantle composition fails to explain the observed gravity field, gravity gradients and surface topography. A tectonically regionalized lithospheric mantle compositional model is able to explain all data sets including seismic tomography models. Our preliminary thermochemical lithospheric study constrains the depth to Moho discontinuity and intra crustal geometries including depth to sediments. We also determine the depth to Curie isotherm which is known as the base of magnetized crustal/uppermost mantle bodies. Discrepancies with respect to previous studies include mantle composition and the geometry of Moho and Lithosphere-Asthenosphere Boundary (LAB). Synthetic seismic Vs and Vp velocities match existing seismic tomography models in the area. In this study, depleted mantle compositions are modelled beneath cold and thick lithosphere in Arabian and Turan platforms. A more fertile mantle composition is found in collision zones. Based on our 3

  7. Petrology and geochemistry of the San Félix-San Ambrosio islands, Eastern Pacific

    Science.gov (United States)

    Cooper Percker, Oliver; Lara, Luis E.

    2015-04-01

    The San Félix-San Ambrosio (SF-SA) islands, Eastern Pacific, are fragments of two volcanic sequences 20 km apart. Both represent the top of an eroded large shield-volcano which rises over the Nazca Plate. Here, new geochemical and 40Ar/39Ar geochronological data are presented in order to understand magmatic evolution and source features. Two units are recognized on the SF island: (1) the Cerro Amarillo unit (CAU) (190±30 ka) formed by a hyaloclastic-tuff cone and basanitic lavas (Ba/Yb=519; Ba/Zr=2.19; La/Yb=49.88; Nb/Ta=17.96; Nb/Y=3.78; Nb/Zr=0.25) with absent or scarce modal content of plagioclase (20%). The hyaloclastic-tuff cone of the CAU contains aphanitic-trachytic lithic fragments of Na-augite and kaersutite, which correspond to the final product of fractional crystallization of olivine+clinopyroxene+Fe-Ti oxides+apatite±plagioclase from alkaline primitive liquids similar to SF-SA lavas. The geochemical data suggest that the islands represent different evolutive stages of a same volcanic intraplate complex. The alkaline to transitional SA lavas (Ba/Yb=249; Ba/Zr=1.60; La/Yb=24.62; Nb/Ta=16.55; Nb/Y=2.22; Nb/Zr=0.19) would represent the shield stage (ca 2.9 Ma), while the basanitic SF lavas the post-erosional stage (ca 0.2 Ma). Considering the Sr-Nd-Pb isotopic data of the SF-SA lavas, previous works have ruled out a genetic relationship between SF-SA islands and the nearby Nazca Ridge. An heterogeneous mantle plume with mantelic metasomatized recycled lithologies is hypothesized as a possible magmatic source capable of explaining the petrologic differences between the SF-SA islands and between the CAU and PU, in SF island. This research is supported by FONDECYT Project 1141303.

  8. Petrological features of suprasubuction mantle: evidence from northern, central and southern Patagonian mantle xenoliths

    Science.gov (United States)

    Melchiorre, M.; Coltorti, M.; Gregoire, M.; Benoit, M.

    2012-04-01

    Patagonia has a number of outcrops where xenoliths-bearing lavas can be found. It thus represents a good opportunity to study mantle material in supra-subduction environment both on arc and back-arc position, from as near as 300 km to as far as 600 km from the Chile trench. A wealth of data is nowadays available on these xenoliths, starting from petrographic observations, whole-rock and mineral major and trace element analyses plus few isotopic analyses on whole rock and mineral separates. To this already large dataset the petrological features of another locality (Estancia Sol de Mayo, ESM) were added, allowing a comparison between as much as eight localities coming from northern (Cerro Aznare, Praguaniyeu, Cerro Rio Chubut, Cerro de los Chenques), central (Cerro Clark and Gobernador Gregores) and southern Patagonia (Pali Aike), covering approximately an area of 1000 x 300 km. Most xenoliths are harzburgites, with minor amount of lherzolites, wehrlites and dunites. In the Al2O3 vs mg# [MgO/(MgO+FeO) mol %] diagram clinopyroxene (cpx) compositions highlight three different trends, with orthopyroxene (opx) compositions plotting on two of these. In the first trend Al2O3 content increases at almost constant mg# mol % (trend 1). The second trend comprises only cpx from wehrlites (trend 2) and is situated between the first and the third trend. In the third trend the slight increases of Al2O3 is associated with a remarkable decrease in mg# (trend 3). LREE and LILE abundances in cpx from Tres Lagos and Cerro Rio Chubut are directly correlated to the Al2O3, while they are inversely correlated at Cerro de Los Chenques and Cerro Fraile. In the first case it is likely that a metasomatic process affects the mantle domains beneath those areas, while in the second case a refertilization event caused by a tholeiitic melt is favorite. In other cases, as for Gobernador Gregores, a more complex situation is recorded, with two groups of samples showing both negative and positive

  9. Sedimentary environments of the Cenozoic sedimentary debris found in the moraines of the Grove Mountains, east Antarctica and its climatic implications

    Institute of Scientific and Technical Information of China (English)

    FANG Aimin; LIU Xiaohan; LEE Jong Ik; LI Xiaoli; HUANG Feixin

    2004-01-01

    During the field work of the 1998~1999's and 1999~2000's Chinese National Antarctic Research Expedition (CHNARE) in the Grove Mountains, east Antarctica, some Cenozoic sedimentary debris are found in two terminal moraine banks over the blue ice near Harding Mount in the center of this region. All the debris are of characteristics of glaciogenic diamicton and belong to the products of the glacial movements of the East Antarctic Ice Sheet. In this paper, the authors make a detailed study on the sedimentary environments of the sedimentary debris through petrologic, sedimentological, mineralogical, and geo-chemical methods. Characteristics of their sedimentary textures and structures, grain size distributions, quartz grains' surface textures and features, together with their geo-chemical compositions all show that these sedimentary rocks are a kind of subglacial lodgement tills which are deposited in the ice sheet frontal area by reactions of glacial movements and glaciogenic melt water. Their palaeoenvironmental implications in revealing the retreat history of East Antarctic Ice Sheet are discussed. The authors draw the conclusion from current study that the glacial frontal of the East Antarctica Ice Sheet might have been retreated to this area during the Pliocene Epoch, which represents a warm climate event accompanied by a large-scale ice sheet retreat in Antarctica at that time.

  10. UKRAINE AND THE EAST: CULTUROLOGICAL ASPECT

    Directory of Open Access Journals (Sweden)

    Oleh Pylypiuk

    2015-05-01

    Full Text Available Modern Oriental studies regard the East as the cradle of the world’s civilization, a web of unique cultural formations. Within the modern East–West paradigm, the research into the values of tradition should be underpinned by dominant axiological concepts in order to systematize contemporary ideas of the world, nature, the individual and mentality. In accordance with the central methodological principle of the research, archetypes are regarded as cultural universals. In the article, the typology of the cosmological and the spiritual elements (the Moon and the Word respectively in the Oriental and Ukrainian traditions are highlighted, the emphasis being laid on the analysis of the semantic and thematic fields of the two archetypes.

  11. Politeness: West and East

    Directory of Open Access Journals (Sweden)

    - Джеффри Лич

    2014-12-01

    Full Text Available The present paper was planned for this issue of our journal, which Geoffrey Leech and I intended to devote to Politeness phenomena across cultures. It is based on his article titled “Politeness: Is there an East-West Divide?” (2005 which he suggested as a theoretical framework and includes results of our discussions held during our personal meetings and our epistolary exchange. Unfortunately the final version of the paper was never read by Geoffrey Leech for the reasons we all sadly know. Nevertheless I decided to publish it as a tribute to him in the knowledge that the result was not going to have the degree of excellence it would have had if he were still with us today. I therefore apologise for any mistakes or misinterpretations of his thoughts that might be found in the paper. The aim of this article is to sum up the main ideas of Politeness Theory presented earlier in Leech 1983, 2003, 2005, and other publications and discuss how that theory applies (or fails to apply to other languages, with the main emphasis on the Russian language and culture. The term ‘maxim’ used in Principles of Pragmatics (Leech 1983 is avoided here as much as possible, as it implies some kind of moral imperative, rather than a pragmatic constraint. Instead, a single constraint, which comprehends all the maxims (the Maxims of Tact, Generosity, Approbation, Modesty, Agreement, Sympathy, and is called the Grand Strategy of Politeness (GSP, is used. The GSP says: In order to be polite, S expresses or implies meanings which place a high value on what pertains to O- his/her wants, qualities, obligation, opinion, feelings (O = other person[s], [mainly the addressee, i.e. H = hearer] or place a low value on what pertains to S (S = self, speaker. The essential point is that these are not separate, independent constraints or maxims: they are instances of the operation of the GSP as ‘super-maxim’ which is an overarching framework for studying linguistic politeness

  12. An integrated model for the natural flow regime in the Cerro Prieto hydrothermal system based upon petrological and isotope geochemical criteria

    Energy Technology Data Exchange (ETDEWEB)

    Elders, W.A.; Williams, A.E.; Hoagland, J..

    1981-01-01

    Studies of cuttings and cores at Cerro Prieto have now been extended to more than 50 boreholes. The aims of this petrological and isotopic work are to determine the shape of the reservoir, its physical properties, and its temperature distribution and flow regime before the steam field was produced.

  13. The importance of coal petrology in petroleum and natural gas prospecting; La importanicia de la petrologia del carbon en la prospeccion de petroleo y gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J.L.

    1992-01-01

    The importance of coal petrology in petroleum and natural gas prospecting lies in the degree of diagenesis of the source and of the reservoir rocks, which can be determined rapidly and precisely by measuring the reflectivity of vitrinite inclusions. 1 fig.

  14. Formation Mechanism and Exhumation Processes for HP-UHP Metamorphic Rocks in Dabie Mountains

    Institute of Scientific and Technical Information of China (English)

    Hou Mingjin; Tang Jiafu

    2004-01-01

    The high, ultrahigh pressure metamorphic rocks, widely distributed in Dabie Mountains, were described in terms of the geological setting, the marks of the petrology and the mineralogy of the ultrahigh pressure (UHP) metamorphic rocks. According to the estimated uplifting and denudation of the Dabie Mountains, and to the thermodynamics theory, were assessed the depth and pressure (high pressure autoclave) of the formation setting of the UHP metamorphic rocks. Based on all the information mentioned above, a new explanation is derived from the mechanism of formation and the processes of exhumation of the UHP metamorphic rocks.

  15. ChemRock: a lithogeochemical data analysis and interpretation system as a tool to the petrological study of igneous rocks and their tectonic setting; ChemRock: um sistema de analise e interpretacao de dados litogeoquimicos como ferramenta para o estudo petrologico de rochas igneas e seu contexto tectonico

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Daisy Barbosa [PETROBRAS S.A., Rio de de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Gerencia de Sedimentologia e Petrologia], E-mail: daisy@petrobras.com.br; Biondi, Mauro; Leta, Fabiana Rodrigues; Lima, Leonardo Pereira de; Valente, Sergio de Castro; Corval, Arthur

    2005-11-15

    Petrology of igneous rocks is strongly based on calculations of whole-rock geochemical data, which applied to a large number of samples can be very time-consuming. This paper presents ChemRock, a computer-based system used to analyze, interpret and visualize lithogeochemical data in a petrologic and geodynamic approach. It operates in a Windows platform and offers a simple and user-friendly interface. Within the same environment it is able to gather rock classification graphs used to discriminate series of tectonic paleo environments, and modules used to interpret normative (CIPW and mesonorm) and isotopic data. Besides, normalization and partition coefficients tables proposed by different authors, quantification modules of partial melting processes, crystal fractionation and binary mixture have been provided. It is capable of generating hundreds of graphs and pre-formatted tables that can be inserted in digital reports, and it is also provided with a module to generate its own reports. ChemRock is a tool to speed up petrogenetic analysis by offering methods and functionalities used in current literature. (author)

  16. Petrological evolution of subducted rodingite from seafloor metamorphism to dehydration of enclosing antigorite-serpentinite (Cerro del Almirez massif, southern Spain)

    Science.gov (United States)

    Laborda-López, Casto; López Sánchez-Vizcaíno, Vicente; Marchesi, Claudio; Gómez-Pugnaire, María Teresa; Garrido, Carlos J.; Jabaloy-Sánchez, Antonio; Padrón-Navarta, José Alberto

    2016-04-01

    . Close to the contact with the blackwall, antigorite-serpentinite is very rich in diopside, olivine and Ti-clinohumite. In this study we present a thermodynamic model of phase relationships in rodingites and transitional blackwalls during their metamorphic history. We mainly aim to establish the evolution of P-T conditions experienced by metarodingites during subduction and the influence of fluids in the formation of mineral assemblages at different metamorphic stages. REFERENCES Padrón-Navarta, J.A., López Sánchez-Vizcaíno, V., Garrido, C.J., Gómez-Pugnaire, M.T., (2011): Metamorphic record of high-pressure dehydration of antigorite serpentinite to chlorite harzburgite in a subduction setting (Cerro Del Almirez, Nevado-Filábride Complex, Southern Spain). Journal of Petrology, 52, 2047-2078.

  17. Petroleum geological investigations in East greenland: project `Resources of the sedimentary basins of North and East Greenland`

    Energy Technology Data Exchange (ETDEWEB)

    Stemmerik, L.; Clausen, O.R.; Larsen, M.; Piasecki, S.; Therkelsen, J. [Geological Survey of Denmark and Greenland, Copenhagen (Denmark); Korstgaard, J. [Univ. of Aarhus, Geological Inst., Aarhus (Denmark); Seidler, L.; Surlyk, F. [Univ. of Copenhagen, Geological Inst., Copenhagen (Denmark)

    1997-12-31

    The multidisciplinary research project `Resources of the sedimentary basins of North and East Greenland` was initiated in 1995. The 1996 field work in East Greenland concentrated on integrated structural, sedimentological and biostratigraphical studies of the Upper Permian and Mesozoic successions. The most important new results arising from the 1996 field work are: 1) Re-interpretation of the Upper Permian Schuchert Dal Formation as a low stand turbidite unit within the Ravnefjeld Formation; 2) Recognition of Middle Jurassic deposits and thick lowermost Cretaceous sandstones on Hold with Hope; 3) Interpretation of a full spectrum of scarp-derived coarse-clastic mass movement deposits inter-bedded with Cretaceous shales on eastern Traill Oe; 4) The presence of a thick sand-rich Cretaceous turbidite succession on eastern Traill Oe; 5) Re-interpretation of the Mesozoic-Cenozoic fault systems on Traill Oe and Geographical Society Oe. (EG) 24 refs.

  18. U.S. and East Asian Integration

    Institute of Scientific and Technical Information of China (English)

    Lin Limin

    2008-01-01

    the U.S. is directly impacting on the future of the East Asian community. Therefore, finding ways to get along with the U.S. is crucial to the speed, direction, configuration and character of the East Asian community. In this paper, the author has analyzed the interests of the United States in East Asia and its stands towards the East Asian integration. The author concludes that it is to the interest of the United States to make more efforts to further join in the East Asian integration.And East Asia should accept and welcome the American participation.

  19. Big Prospects in East Asia

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    After bottoming out last year, the emerging economies of East Asia are recouping their losses and setting out onto the fast growth track.But short-term growth does not necessarily indicate a prosperous future-the region still needs to rebalance its economies and precipitate a massive shift to green technologies and energy efficiency. The World Bank discussed this issue in the latest EastAsia & Pacific Economic Update,a biannual assessment of economies in the region.Edited excerpts follow:

  20. Physical properties, morphology and petrological characteristics of pumices from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.; Ilangovan, D.

    from a source nearer to the site of deposition, which could be within or near the CIOB. The experiments by Whitham and Sparks (1986) support the theory that hot pumice sinks immediately on immersion in water despite having a lower density than water... of the Ninety East Ridge and the absence of a 12 favourable surface current circulation patterns in this region (Fairbridge, 1966; Frick and Kent, 1984) cast doubt on the drift theory for the CIOB pumice. Although pumice recovered from deeper areas...

  1. Petrología, evolución geodinámica y georrecursos del Espacio Natural de Sierra Nevada

    Directory of Open Access Journals (Sweden)

    Díaz Puga, M. A.

    2007-12-01

    Full Text Available We show the spatial distribution of the various geological formations that make up the Veleta and Mulhacén Complexes into the Sierra Nevada Park and illustrate, with macro- and microscopic photographs, their most characteristic types of rock. The Veleta and Mulhacén Complexes were previously considered together as the Nevado-Filábride Complex. They constitute the deepest units of the Betic Cordilleras and crop out in Sierra Nevada forming the highest pics of the Iberian Peninsula. The Veleta Complex (VC is formed of several thousand metres of graphite-bearing micaschists and crops out as a series of tectonic windows below the Mulhacén Complex (MC. This latter complex comprises two thrust nappes of crustal origin, composed of a Palaeozoic basement and Mesozoic cover series, between which a Jurassic-Cretaceous ophiolitic nappe is tectonically intercalated. Within the MC nappes of crustal origin, there appear meta-granitic rocks, generated in a late-Hercynian syn-collisional magmatism and a Permian to Triassic, post-collisional intraplate, acidic-to-intermediate volcanism. The ophiolitic nappe is composed of basic, ultramafic and sedimentary rocks affected by ocean-floor and orogenic metamorphism. The basic rocks mainly retain their original MORB character. The ultramafic rocks are serpentinites and secondary harzburgites containing partly rodingitized meta-basaltic dykes. The Alpine metamorphism developed eclogite facies followed by Ab-Ep amphibolite facies in the MC and Ab-Ep amphibolite facies followed by greenschist facies in the VC. The different tectonic units forming the Veleta and Mulhacén Complexes, so as the Soportujar Formation, which was deposited over the MC units during an alpine intraorogenic stage, were defined from outcrops very well represented into the Natural Space of Sierra Nevada. These outcrops constitute a series of petrological georesources, which are essential to reconstruct the origin and petrogenetic evolution of

  2. Co-axial superposed folding and inverted regional metamorphism in the Tonga Formation: Cretaceous accretionary thrust tectonics in the Cascades crystalline core

    Science.gov (United States)

    Luke, Jensen; Lebit, Hermann; Paterson, Scott; Miller, Robert; Vernon, Ron

    2017-04-01

    context, the Tonga Formation, on the westernmost boundary of the Cascades crystalline core, records Cretaceous plutonism, contact to regional metamorphism, and multiple episodes of folding, evidencing intense, arc-perpendicular contractional deformation, similar to that observed in the neighboring Chiwaukum Schist to the east (Miller and Paterson, 1992; Miller et al., 1993; Paterson and Miller, 1998; Miller et al., 2006). Building on previous extensive mapping and metamorphic and petrologic analysis in the Cascades, we use the Tonga Formation as a means to a comprehensive tectonic synthesis incorporating detailed analysis of the kinematics and timing of structural evolution, magma emplacement, and metamorphism.

  3. Physical and petrologic properties of ordinary chondrites and their taxonomic parameters%普通球粒陨石的物理和岩石学性质及其分类参数

    Institute of Scientific and Technical Information of China (English)

    王道德; 王桂琴

    2011-01-01

    不同球粒陨石群的物理和岩石学性质,包括球粒的平均大小、球粒结构类型、复合球粒、带火成边球粒及含硫化物的比例、化学组成及矿物学特征等可用以划分球粒陨石的化学-岩石类型和小行星类型,这些性质提供了不同球粒陨石群有用的分类参数及其形成环境的信息.由于不同球粒陨石群的△17O与日心距离存在有相关关系,因此,依据不同球粒陨石群形成时的尘粒量和△17O值随着距太阳距离的增大依次形成:EH-EL、OC(H、L、LL)、R、CR、CV-CK、CM-CO球粒陨石群,并推测早期太阳星云内曾发生过连续的化学分馏作用.%The physical and petrologic properties of the different chondrite groups, including mean size of the chondrules, proportions of the chondrule textural types, proportions of compound chondrule, the proportions of chondrules with igneous rims. and the proportions of chondrules that contain sulfide, chemical compositions and mineral features derived from the early solar nebula are used to classify chemical-petrologic types and asteroids.These properties provided useful taxonomic parameters for different chondrite group (EH, EL, H, L. LL. R, CV,CK. CR, CM, CO) and the information of their formation environment in which chondrules formed. There is correlation between △17O and heliocentric distance for these chondrite groups. Thus, different chondrite groups may be put in the order of EH-EL. OC (H, L, LL), R, CR. CV-CK. CM-CO, with increasing heliocentric formation distance. based on the amount of dust present where they formed and △17O values of different chondrite groups.We infer that continual chemical fractionation occurred in the early solar system.

  4. Composition of uppermost mantle beneath the Northern Fennoscandia - numerical modeling and petrological interpretation

    Science.gov (United States)

    Virshylo, Ivan; Kozlovskaya, Elena; Prodaivoda, George; Silvennoinen, Hanna

    2013-04-01

    Studying of the uppermost mantle beneath the northern Fennoscandia is based on the data of the POLENET/LAPNET passive seismic array. Firstly, arrivals of P-waves of teleseismic events were inverted into P-wave velocity model using non-linear tomography (Silvennoinen et al., in preparation). The second stage was numerical petrological interpretation of referred above velocity model. This study presents estimation of mineralogical composition of the uppermost mantle as a result of numerical modeling. There are many studies concerning calculation of seismic velocities for polymineral media under high pressure and temperature conditions (Afonso, Fernàndez, Ranalli, Griffin, & Connolly, 2008; Fullea et al., 2009; Hacker, 2004; Xu, Lithgow-Bertelloni, Stixrude, & Ritsema, 2008). The elastic properties under high pressure and temperature (PT) conditions were modelled using the expanded Hook's law - Duhamel-Neumann equation, which allows computation of thermoelastic strains. Furthermore, we used a matrix model with multi-component inclusions that has no any restrictions on shape, orientation or concentration of inclusions. Stochastic method of conditional moment with computation scheme of Mori-Tanaka (Prodaivoda, Khoroshun, Nazarenko, & Vyzhva, 2000) is applied instead of traditional Voigt-Reuss-Hill and Hashin-Shtrikman equations. We developed software for both forward and inverse problem calculation. Inverse algorithm uses methods of global non-linear optimization. We prefer a "model-based" approach for ill-posed problem, which means that the problem is solved using geological and geophysical constraints for each parameter of a priori and final models. Additionally, we are checking at least several different hypothesis explaining how it is possible to get the solution with good fit to the observed data. If the a priori model is close to the real medium, the nearest solution would be found by the inversion. Otherwise, the global optimization is searching inside the

  5. The East Asian Subtropical Summer Monsoon:Recent Progress

    Institute of Scientific and Technical Information of China (English)

    何金海; 刘伯奇

    2016-01-01

    The East Asian subtropical summer monsoon (EASSM) is one component of the East Asian summer monsoon system, and its evolution determines the weather and climate over East China. In the present paper, we fi rstly demonstrate the formation and advancement of the EASSM rainbelt and its associated circulation and precipitation patterns through reviewing recent studies and our own analysis based on JRA-55 (Japanese 55-yr Reanalysis) data and CMAP (CPC Merged Analysis of Precipitation), GPCP (Global Precipitation Climatology Pro ject), and TRMM (Tropical Rainfall Measuring Mission) precipitation data. The results show that the rainy season of the EASSM starts over the region to the south of the Yangtze River in early April, with the establishment of strong southerly wind in situ. The EASSM rainfall, which is composed of dominant convective and minor stratiform precipitation, is always accompanied by a frontal system and separated from the tropical summer monsoon system. It moves northward following the onset of the South China Sea summer monsoon. Moreover, the role of the land–sea thermal contrast in the formation and maintenance of the EASSM is illustrated, including in particular the eff ect of the seasonal transition of the zonal land–sea thermal contrast and the infl uences from the Tibetan Plateau and midlatitudes. In addition, we reveal a possible reason for the subtropical climate diff erence between East Asia and East America. Finally, the multi-scale variability of the EASSM and its infl uential factors are summarized to uncover possible reasons for the intraseasonal, interannual, and interdecadal variability of the EASSM and their importance in climate prediction.

  6. The East Asian subtropical summer monsoon: Recent progress

    Science.gov (United States)

    He, Jinhai; Liu, Boqi

    2016-04-01

    The East Asian subtropical summer monsoon (EASSM) is one component of the East Asian summer monsoon system, and its evolution determines the weather and climate over East China. In the present paper, we firstly demonstrate the formation and advancement of the EASSM rainbelt and its associated circulation and precipitation patterns through reviewing recent studies and our own analysis based on JRA-55 (Japanese 55-yr Reanalysis) data and CMAP (CPC Merged Analysis of Precipitation), GPCP (Global Precipitation Climatology Project), and TRMM (Tropical Rainfall Measuring Mission) precipitation data. The results show that the rainy season of the EASSM starts over the region to the south of the Yangtze River in early April, with the establishment of strong southerly wind in situ. The EASSM rainfall, which is composed of dominant convective and minor stratiform precipitation, is always accompanied by a frontal system and separated from the tropical summer monsoon system. It moves northward following the onset of the South China Sea summer monsoon. Moreover, the role of the land-sea thermal contrast in the formation and maintenance of the EASSM is illustrated, including in particular the effect of the seasonal transition of the zonal land-sea thermal contrast and the influences from the Tibetan Plateau and midlatitudes. In addition, we reveal a possible reason for the subtropical climate difference between East Asia and East America. Finally, the multi-scale variability of the EASSM and its influential factors are summarized to uncover possible reasons for the intraseasonal, interannual, and interdecadal variability of the EASSM and their importance in climate prediction.

  7. Preliminary evaluation of fluid chemistry in the East Mesa KGRA

    Energy Technology Data Exchange (ETDEWEB)

    Hoagland, J.R.

    1976-10-04

    One of the major problems needing consideration when bringing a geothermal field into production is the anticipation and control of mineral precipitation in both the producing formations and production equipment. Prediction of the chemical interactions between natural multicomponent thermal fluids and the minerals comprising a producing formation can be accomplished by the study of equilibrium models approximating the natural system. Models are constructed from theoretically and experimentally derived thermodynamic data for the involved minerals and aqueous species. This equilibrium modeling approach was applied to the rock-water system at the East Mesa geothermal area in the Imperial Valley of California. Results of petrographic and fluid analyses are given. (JGB)

  8. A fundamental dispute: A discussion of "On some fundamentals of igneous petrology" by Bruce D. Marsh, Contributions to Mineralogy and Petrology (2013) 166: 665-690

    Science.gov (United States)

    Latypov, Rais; Morse, Tony; Robins, Brian; Wilson, Richard; Cawthorn, Grant; Tegner, Christian; Holness, Marian; Lesher, Charles; Barnes, Steve; O'Driscoll, Brian; Veksler, Ilya; Higgins, Michael; Wilson, Allan; Namur, Olivier; Chistyakova, Sofya; Naslund, Richard; Thy, Peter

    2015-02-01

    Marsh (Contrib Miner Petrol 166:665-690, 2013) again claims that crystal-free basalt magmas are unable to differentiate in crustal magma chambers and regards layered intrusions as primarily due to the repeated emplacement of crystal suspensions. He ignores an earlier critique of his unconventional inferences (Latypov, J Petrol 50:1047-1069, 2009) as well as a wealth of petrographic, geochemical and experimental evidence supporting the dominant role of fractional crystallization in the solidification of layered intrusions. Most tellingly, the cryptic variations preserved in the Skaergaard and many other basaltic layered intrusions would require an exceedingly implausible sequence of phenocrystic magmas but are wholly consistent with in situ fractional crystallization. A major flaw in Marsh's hypothesis is that it dismisses progressive fractional crystallization within any magma chamber and hence prohibits the formation of crystal slurries with phenocrysts and melts that change systematically in composition in any feeder system. This inherent attribute of the hypothesis excludes the formation of layered intrusions anywhere.

  9. Nonmetric cranial trait variation and population history of medieval East Slavic tribes.

    Science.gov (United States)

    Movsesian, Alla A

    2013-12-01

    The population history of the East Slavs is complicated. There are still many unanswered questions relating to the origins and formation of the East Slavic gene pool. The aims of the current study were as follows: (1) to assess the degree of biological affinity in medieval East Slavic tribes and to test the hypothesis that East Slavic peoples have a common origin; (2) to show their genetic connections to the autochthonous populations of the northern part of Eastern Europe (Baltic and Finno-Ugric tribes); and (3) to identify a genetic continuity between the bearers of Chernyakhov culture and medieval Eastern Slavs. In this study, nonmetric cranial trait data for medieval East Slavic tribes and comparative samples from unrelated groups were examined. Analyzes of phenotypic differentiation were based on Nei's standard genetic distance and hierarchical GST statistics. The results obtained suggest that the genetic affinity of the East Slavic tribes is due not only to inter-tribal gene flow, but is, more importantly, a result of their common population history. Evidence of gene flow from the Baltic and Finno-Ugric groups was showed in the gene pool of Eastern Slavs, as was genetic continuity between medieval East Slavic tribes and the populations of the preceding Chernyakhov culture. These findings support a "generalizing" hypothesis of East Slavic origin, in which a Slavic community was formed in some particular ancestral area, and subsequently spread throughout Eastern Europe.

  10. Ca-Eskola incorporation in clinopyroxene: limitations and petrological implications for eclogites and related rocks

    Science.gov (United States)

    Schroeder-Frerkes, F.; Woodland, A. B.; Uenver-Thiele, L.; Klimm, K.; Knapp, N.

    2016-12-01

    Clinopyroxene is an essential mineral in eclogitic rocks. It commonly contains minor amounts of the defect-bearing Ca-Eskola (CaEs, Ca0.5□0.5AlSi2O6) component, with higher concentrations generally considered to indicate a high-pressure origin at least within the coesite stability field. Changes in pressure and temperature conditions can lead to exsolution of this component as a free SiO2 phase, which may have a number of petrological implications. This makes it important to understand the factors that maximize CaEs incorporation in clinopyroxene. We have undertaken a series of experiments at high pressures and temperatures (4-10 GPa and 1000-1350 °C) to further investigate the systematics of CaEs incorporation in eclogite-like clinopyroxene and the factors responsible for maximizing CaEs contents. Two simple chemical systems were chosen that allow unambiguous interpretation of the results: (1) CMAS + H2O and (2) two compositions in the NCMAS system. All experimental products contained clinopyroxene and garnet along with either a free SiO2 phase or a silicate melt. Coexisting garnet is grossular-rich, generally with X gr ≥ 0.67. Compositional variations are attributable to the presence or absence of melt and changes in modal amounts of garnet at different pressure-temperature conditions. Even small amounts of H2O lower the solidus temperature and the presence of a melt reduces the SiO2 activity, which destabilizes the CaEs component in clinopyroxene. The CaEs and the Ca-Tschermaks (CaTs, CaAl2SiO6) components in clinopyroxene decrease with increasing jadeite mole fraction, which is also a function of pressure and bulk Al content. Modeling X-ray powder diffraction data yields a molar volume for the CaEs endmember of V CaEs = 60.87(63) cm3, which reasonably agrees with a literature value that was estimated from natural samples. In the presence of coexisting coesite, the CaEs and CaTs do not vary independently of each other, being controlled by the internal

  11. Petrological, organic geochemical and geochemical characteristics of coal from the Soko mine, Serbia

    Energy Technology Data Exchange (ETDEWEB)

    Zivotic, Dragana; Simic, Vladimir [Faculty of Mining and Geology, University of Belgrade, Djusina 7, 11000 Belgrade (RS); Wehner, Herman; Scheeder, Georg; Vidal, Angelika [Bundesanstalt fuer Geowissenschaften und Rohstoffe, Stilleweg 2, 30655 Hannover (Germany); Cvetkovic, Olga; Sajnovic, Aleksandra [Center of Chemistry, IChTM, Studentski trg 16, 11000 Belgrade (RS); Jovancicevic, Branimir [Center of Chemistry, IChTM, Studentski trg 16, 11000 Belgrade (RS); Faculty of Chemistry, University of Belgrade, Studentski trg 16, 11000 Belgrade (RS); Grzetic, Ivan [Faculty of Chemistry, University of Belgrade, Studentski trg 16, 11000 Belgrade (RS); Ercegovac, Marko [Serbian Academy of Sciences and Arts, Knez Mihailova 35,11000 Belgrade (RS)

    2008-02-01

    A petrological, organic geochemical and geochemical study was performed on coal samples from the Soko Mine, Soko Banja basin, Serbia. Ten coal and two carbonaceous clay samples were collected from fresh, working faces in the underground brown coal mine from different parts of the main coal seam. The Lower Miocene, low-rank coal of the Soko Mine is a typical humic coal with huminite concentrations of up to 76.2 vol.%, liptinite less than 14 vol.% and inertinite less than 11 vol.%. Ulminite is the most abundant maceral with variable amounts of densinite and clay minerals. Sporinite and resinite are the most common macerals of the liptinite group. Inertodetrinite is the most abundant maceral of the inertinite group. The mineral-bituminous groundmass identified in some coal samples, and carbonaceous marly clay, indicate sub-aquatic origin and strong bacterial decomposition. The mean random huminite reflectance (ulminite B) for the main coal seam is 0.40 {+-} 0.05% Rr, which is typical for an immature to early mature stage of organic matter. The extract yields from the coal of the Soko Banja basin ranges from 9413 to 14,096 ppm, in which alkanes constituted 1.0-20.1%, aromatics 1.3-14.7%, asphaltenes 28.1-76.2% and resins 20.2-43.5%. The saturated hydrocarbon fractions included n-C{sub 15} to n-C{sub 32}, with an odd carbon number that predominate in almost all the samples. The contents of n-C{sub 27} and n-C{sub 29} alkanes are extremely high in some samples, as a contribution of epicuticular waxes from higher plants. Acyclic isoprenoid hydrocarbons are minor constituents in the aliphatic fraction, and the pristane/phytane (Pr/Ph) ratio varies between 0.56 and 3.13, which implies anaerobic to oxic conditions during sedimentation. The most abundant diterpanes were abietane, dehydroabietane and 16{alpha}(H)-phyllocladane. In samples from the upper part of the coal seam, diterpanes are the dominant constituents of the alkane fraction. Polycyclic alkanes of the triterpane

  12. East Man,Global Winner

    Institute of Scientific and Technical Information of China (English)

    Wind Blew; Bai Yifeng

    2007-01-01

    @@ "The Global Human Settlement Environment Green Building Materials Award is a special award with a special significance.My staff and I feel so excited with this award.It is a special honor that means our independent brand,East Man Heath Paint,has received recognition in the international community.

  13. Forests of East Texas, 2014

    Science.gov (United States)

    Thomas J. Brandeis

    2015-01-01

    This resource update provides an overview of forest resources in east Texas derived from an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) Program at the Southern Research Station in cooperation with the Texas A&M Forest Service. These estimates are based on field data collected using the FIA annualized sample design and are...

  14. Forests of east Texas, 2015

    Science.gov (United States)

    Kerry J.W. Dooley

    2017-01-01

    This resource update provides an overview of forest resources in east Texas based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Southern Research Station (SRS) in cooperation with Texas A&M Forest Service. The 254 counties of Texas are consolidated into seven FIA survey units—Southeast (unit 1),...

  15. Forests of east Texas, 2013

    Science.gov (United States)

    K.J.W. Dooley; T.J. Brandeis

    2014-01-01

    This resource update provides an overview of forest resources in east Texas based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Southern Research Station in cooperation with the Texas A&M Forest Service. Forest resource estimates are based on field data collected using the FIA annualized sample design and...

  16. Great Explorers to the East.

    Science.gov (United States)

    Baker, Rosalie F., Ed.; Baker, Charles F. III, Ed.

    1990-01-01

    This issue of "Calliope," a world history magazine for young people is devoted to "Great Explorers of the East" and features articles on famous explorers of the eastern hemisphere. The following articles are included: "Ancient Egyptian Mariners"; "Alexander: The Great Reconciler"; "Marco Polo:…

  17. Great Explorers to the East.

    Science.gov (United States)

    Baker, Rosalie F., Ed.; Baker, Charles F. III, Ed.

    1990-01-01

    This issue of "Calliope," a world history magazine for young people is devoted to "Great Explorers of the East" and features articles on famous explorers of the eastern hemisphere. The following articles are included: "Ancient Egyptian Mariners"; "Alexander: The Great Reconciler"; "Marco Polo: Describing the World"; "By Water to India";…

  18. East African odontopygid millipedes 1

    DEFF Research Database (Denmark)

    Frederiksen, Sara B.; Enghoff, Henrik

    2012-01-01

    Five new species of the endemic East African genus Xystopyge are described: X. pelecys, X. frontieri, X. proplicatus, X. biacanthus, and X. zanzibarensis. Three are from the Eastern Arc Mountains, Tanzania, two are from the Usambara Mtns. and one is from the Uluguru Mtns. One further species is f...

  19. Petrologic insights into basaltic volcanism at historically active Hawaiian volcanoes: Chapter 6 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Helz, Rosalind L.; Clague, David A.; Sisson, Thomas W.; Thornber, Carl R.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Study of the petrology of Hawaiian volcanoes, in particular the historically active volcanoes on the Island of Hawai‘i, has long been of worldwide scientific interest. When Dr. Thomas A. Jaggar, Jr., established the Hawaiian Volcano Observatory (HVO) in 1912, detailed observations on basaltic activity at Kīlauea and Mauna Loa volcanoes increased dramatically. The period from 1912 to 1958 saw a gradual increase in the collection and analysis of samples from the historical eruptions of Kīlauea and Mauna Loa and development of the concepts needed to evaluate them. In a classic 1955 paper, Howard Powers introduced the concepts of magnesia variation diagrams, to display basaltic compositions, and olivine-control lines, to distinguish between possibly comagmatic and clearly distinct basaltic lineages. In particular, he and others recognized that Kīlauea and Mauna Loa basalts must have different sources.

  20. Crude oil as carrier of gold: petrological and geochemical evidence from Lannigou gold deposit in southwestern Guizhou, China

    Institute of Scientific and Technical Information of China (English)

    庄汉平; 卢家烂; 傅家谟; 任炽刚; 邹德刚

    1999-01-01

    Organic matter is related closely to mineralization of Lannigou gold deposit in southwestern Guizhou, China, Regionally, the distribution of organic carbon agrees well with that of faults within which gold deposits are hosted. Studies on organic petrology show that pyrobiturnen, which is related most closely to mineralization, adheres to quartz vein or fills quartz veinlet. Proton-induced X-ray emission (PIXE) analysis shows an evident abundance of Au in pyrobitumen. Pyrobitumen paragenetically associates with pyrite and arsenopyrite which are the main carrier minerals of Au. The thermal simulation experiment indicates that about 99% of Au will be concentrated in oil phase in the coexisting system of oil and brine and rock. The role of crude oil in ore-forming process is: as carrier of Au, crude oil moves upwards, and undergoes thermal decomposition and thermochemical reduction when it encounters the oxidizing fluid within the Trassic turbidity; Au is thus released from crude oil, reduced and precipitat

  1. Tectonic structure and post-Hercynian evolution of the Serre, Calabrian Arc, southern Italy: Geological, petrological and radiometric evidences

    Science.gov (United States)

    Moro, Aldo Del; Paglionico, Antonio; Piccarreta, Giuseppe; Rottura, Alessandro

    1986-04-01

    Conflicting opinions exist concerning the structure and the post-Hercynian evolution of the Serre. The present paper deals with these topics on the basis of new geological, petrological and radiometric evidence. The composition of the so-called Stilo and Polia-Copanello units has been redefined. The above domains—former sections of upper and lower Palaeozoic continental crust respectively—came into contact, due to transcurrent movements 130-140 Ma ago. A significant vertical component during the transcurrent movements, probably, exhumed the former section of lower crust. The above domains, juxtaposed, were successively involved as a single kinematic body in the Alpine orogenesis. The results enable us to make inferences for the Calabrian Arc evolution and call attention to similarities between an Austro-Alpine element (Stilo + Polia-Copanello) of the Calabrian chain and a South-Alpine sector of the Alps (Ivrea + Ceneri zones).

  2. Petrologic and petrophysical evaluation of the Dallas Center Structure, Iowa, for compressed air energy storage in the Mount Simon Sandstone.

    Energy Technology Data Exchange (ETDEWEB)

    Heath, Jason E.; Bauer, Stephen J.; Broome, Scott Thomas; Dewers, Thomas A.; Rodriguez, Mark A

    2013-03-01

    The Iowa Stored Energy Plant Agency selected a geologic structure at Dallas Center, Iowa, for evaluation of subsurface compressed air energy storage. The site was rejected due to lower-than-expected and heterogeneous permeability of the target reservoir, lower-than-desired porosity, and small reservoir volume. In an initial feasibility study, permeability and porosity distributions of flow units for the nearby Redfield gas storage field were applied as analogue values for numerical modeling of the Dallas Center Structure. These reservoir data, coupled with an optimistic reservoir volume, produced favorable results. However, it was determined that the Dallas Center Structure cannot be simplified to four zones of high, uniform permeabilities. Updated modeling using field and core data for the site provided unfavorable results for air fill-up. This report presents Sandia National Laboratories petrologic and petrophysical analysis of the Dallas Center Structure that aids in understanding why the site was not suitable for gas storage.

  3. Slab Stagnation and Buckling in the Mantle Transition Zone: Petrology, Rheology, and the Geodynamics of Trench Migration

    Science.gov (United States)

    Bina, C. R.; Čížková, H.

    2015-12-01

    Recent work indicates that subducting slabs may exhibit buckling instabilities and consequent folding behavior in the mantle transition zone for various dynamical parameters, accompanied by temporal variations in dip angle, plate velocity, and trench retreat. Governing parameters include both viscous (rheological) and buoyancy (thermo-petrological) forces. 2D numerical experiments show that many parameter sets lead to slab deflection at the base of the transition zone, typically accompanied by quasi-periodic oscillations in largely anticorrelated plate and rollback velocities, resulting in undulating stagnant slabs as buckle folds accumulate subhorizontally atop the lower mantle. Slab petrology, of mantle phase transitions and hydrated crust, is a dominant factor in this process (Čížková and Bina, 2013). For terrestrial parameter sets, trench retreat is found to be nearly ubiquitous and trench advance quite rare, largely due to rheological and ridge-push effects. Recently updated analyses of global plate motions indicate that significant trench advance is also rare on Earth, being largely restricted to the Izu-Bonin arc (Matthews et al., 2013). Thus, we explore conditions necessary for terrestrial trench advance through dynamical models involving the unusual geometry of the Philippine Sea region. Our 2D modeling of such geometries, in which distal subduction of the overriding plate overprints an opposed slab-pull force on the usual ridge-push at the trench, yields persistent trench advance interrupted by episodes of back-arc extension, demonstrating that trench advance can occur for terrestrial rheologies in such special geometries (Čížková and Bina, 2015).

  4. Solving petrological problems through machine learning: the study case of tectonic discrimination using geochemical and isotopic data

    Science.gov (United States)

    Petrelli, Maurizio; Perugini, Diego

    2016-10-01

    Machine-learning methods are evaluated to study the intriguing and debated topic of discrimination among different tectonic environments using geochemical and isotopic data. Volcanic rocks characterized by a whole geochemical signature of major elements (SiO2, TiO2, Al2O3, Fe2O3T, CaO, MgO, Na2O, K2O), selected trace elements (Sr, Ba, Rb, Zr, Nb, La, Ce, Nd, Hf, Sm, Gd, Y, Yb, Lu, Ta, Th) and isotopes (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 87Sr/86Sr and 143Nd/144Nd) have been extracted from open-access and comprehensive petrological databases (i.e., PetDB and GEOROC). The obtained dataset has been analyzed using support vector machines, a set of supervised machine-learning methods, which are considered particularly powerful in classification problems. Results from the application of the machine-learning methods show that the combined use of major, trace elements and isotopes allows associating the geochemical composition of rocks to the relative tectonic setting with high classification scores (93 %, on average). The lowest scores are recorded from volcanic rocks deriving from back-arc basins (65 %). All the other tectonic settings display higher classification scores, with oceanic islands reaching values up to 99 %. Results of this study could have a significant impact in other petrological studies potentially opening new perspectives for petrologists and geochemists. Other examples of applications include the development of more robust geothermometers and geobarometers and the recognition of volcanic sources for tephra layers in tephro-chronological studies.

  5. Incorporating Problem-Based Learning Into A Petrology Course Through A Research Project In The Local Northern Sierra Nevada

    Science.gov (United States)

    Aird, H. M.

    2016-12-01

    A research project into the local petrology was integrated into the Spring 2016 Petrology and Optical Mineralogy course at California State University, Chico. This is a required majors course, typically taken during spring of the junior year, with an enrollment of 10-20 students. Since the labs for this course have a strong focus on petrography, a research project was introduced to give students experience in using a multi-faceted approach to investigate a problem. In many cases, this is their first taste of research. During the first week of the Spring 2016 class, students were introduced to the research question: In the broader context of Californian tectonic history, are the Bucks Lake and Grizzly plutons of the northern Sierra Nevada petrogenetically related? With faculty guidance over the course of the semester, students carried out fieldwork and sampling, lithologic description, selection of the best samples for further analysis, thin section production, petrographic description, and analysis and interpretation of published geochemical data. Research activities were strategically scheduled within the course framework such that students were academically prepared to carry out each task. Each student was responsible for generating all the data for one sample, and data were then collated as a class, so students wrote their individual final reports using all the data collected by the class. Careful scaffolding of writing assignments throughout the semester guided students through the preparation of an academic-style scientific report, while allowing for repeated feedback on their writing style and content. In mid-May, the class presented a group poster at the College of Natural Sciences annual poster symposium, and were awarded `Best Student Class Project' by the judges. Anecdotal student feedback indicated they highly valued the research experience and some were inspired to pursue individual undergraduate research projects under faculty supervision.

  6. The Formation of Yanshanian Granitic Magma in Dabie Mountains:Dehydration or Aquifer Melting with Tiantangzhai and Jiuzihe Granites as Examples

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; ZHAO Zhenhua; QIU Jiaxiang; WANG Renjing; XU Jifeng

    2001-01-01

    There are large-areas of late Yanshanian granites in the Dabie Orogen, but the formation mode of the relevant granitic magma is still under discussion. Taking the typical Yanshanian granites in the North Dabie Block The TG and JG as examples, the Writers endeavor to discuss contain aspects of the formation mode of the granitic magma by studying the characteristics of the chemical compositions of biotite and amphibole of the granites and petrological features of enclaves in the intrusions, in the light of recent results of experimental petrology on dehydration melting and aquifer melting. It is suggested that: (1) Some biotites in the Tiantangzhai and the JGs and their enclaves were residual minerals; (2) Some of the amphiboles could be new-born minerals, and others, residual ones.(3) the banded bodies in granites were residuals of anatexis. (4) The TG and JG were formed by aquifer melting, and the South Dabie Block could be the important source region of water.

  7. Funding problems threaten Middle East's synchrotron

    CERN Multimedia

    McCabe, H

    1999-01-01

    Scientists will tour the Middle East to try to raise support for the Synchrotron radiation for Experimental Science and Applications in the Middle East project. The plan is to dismantle and move a decommissioned synchrotron from Berlin to the Middle East where scientists of any nationality would be able to use it (3 paragraphs).

  8. Karaoke and Interpersonal Communication in East Asia.

    Science.gov (United States)

    Ma, Ringo

    An exploratory study investigated the interpersonal meaning of karaoke to its participants in East Asia. Current research suggests that the popularity of karaoke in East Asia is associated with the cultural value of harmony and the indirect mode of communication in this region. Subjects, 51 East Asian undergraduate-level students who had…

  9. Experiencing the New Geography in East Germany.

    Science.gov (United States)

    Mai, Uli; Burpee, Peter

    1996-01-01

    Considers the difficulties experienced by the East German School system adjusting to a more progressive educational philosophy. Specifically, contrasts the traditional East German geography instruction (focused solely on physical geography) with the West German emphasis on social issues and problem solving. Many East German instructors distrust…

  10. The East Greenland rifted volcanic margin

    Directory of Open Access Journals (Sweden)

    C. Kent Brooks

    2011-12-01

    the emplacement of small volumes of basalts of the Vindtoppen Formation to the south of Scoresby Sund.Although the basalts were extruded close to sea level, this part of East Greenland is a plateau raised to c. 2 km, but the timing of uplift is controversial. Superimposed on the plateau is a major dome at Kangerlussuaq.East Greenland presents a rich interplay between magmatic and tectonic events reflecting the birth of the North Atlantic Ocean. It was active over a much longer period (36 Ma than other parts of the province (5 Ma in the Hebrides, Northern Ireland and the Faroe Islands and contains a wider range of products, including carbonatites, and felsic rocks tend to be granitic rather than syenitic. As expected, there are many similarities with Iceland, the present-day expression of activity in the province. Differences are readily explained by higher production rates and the thicker lithospheric lid during the early stages of development in East Greenland. The igneous and related activity clearly results from plate-tectonic factors, but the relationship is not understood in detail. In particular, the nature of the underlying mantle processes, primarily the presence or absence of a plume, is still not resolved.

  11. Investigation on Swells of the East China Sea

    Science.gov (United States)

    Tao, Aifeng; Wu, Chao

    2017-04-01

    In the recent decades, more and more human activities, including different kinds of marine structures and large ships, have been present in the East China Sea. It is necessary to fasten our attentions on the marine safety issues, particularly on the extreme waves. Because it has been known that the density of extreme waves may increase with Typhoon in the future with the global climate changing. The extreme waves can be induced not only by Typhoon in summer, but also by East Asian cold waves in winter for this special sea area. And the swells also can be very dangerous because the swells may result in the resonance with floating structures, including the ships. Focusing on the investigation of swells in the East China Sea, the hindcast for waves in the past ten years will be performed by the numerical model Wave Watch III based on the historical climate data. The numerical calculation domain covers the whole North West Pacific. Then the swells will be separated and analyzed from the simulated wave fields. Both the characteristics and the generation mechanisms of the swells will be investigated. Particularly, the swells, which propagating across the Ryukyu chain from east to west, will be analyzed in details. We used the CCMP & Myers wind data to run the WW3 model and reproduced the global wave fields in 2010-2014. After separating swell and wind sea from mixed waves, we studied the spatial and temporal distribution of swell in East China Sea and the formation mechanism of swell in East China Sea.The significant wave heights of swells in the East China Sea are mainly distributed in the 0.1-2.5m, the interval with the highest frequency of occurrence is 0.1-0.5m, and the proportion is about 50%. The spectrum peak periods of swells are mainly distributed in the 4-15s, the interval with the highest frequency of occurrence is 9-15s., and the proportion is about 25%. In terms of spatial distribution swells increase gradually from the offshore to deep sea, and also

  12. Stable isotope and petrologic evidence for open-system degassing during the climactic and pre-climactic eruptions of Mt. Mazama, Crater Lake, Oregon

    Science.gov (United States)

    Mandeville, C.W.; Webster, J.D.; Tappen, C.; Taylor, B.E.; Timbal, A.; Sasaki, A.; Hauri, E.; Bacon, C.R.

    2009-01-01

    Evaluation of the extent of volatile element recycling in convergent margin volcanism requires delineating likely source(s) of magmatic volatiles through stable isotopic characterization of sulfur, hydrogen and oxygen in erupted tephra with appropriate assessment of modification by degassing. The climactic eruption of Mt. Mazama ejected approximately 50 km3 of rhyodacitic magma into the atmosphere and resulted in formation of a 10-km diameter caldera now occupied by Crater Lake, Oregon (lat. 43??N, long. 122??W). Isotopic compositions of whole-rocks, matrix glasses and minerals from Mt. Mazama climactic, pre-climactic and postcaldera tephra were determined to identify the likely source(s) of H2O and S. Integration of stable isotopic data with petrologic data from melt inclusions has allowed for estimation of pre-eruptive dissolved volatile concentrations and placed constraints on the extent, conditions and style of degassing. Sulfur isotope analyses of climactic rhyodacitic whole rocks yield ??34S values of 2.8-14.8??? with corresponding matrix glass values of 2.4-13.2???. ??34S tends to increase with stratigraphic height through climactic eruptive units, consistent with open-system degassing. Dissolved sulfur concentrations in melt inclusions (MIs) from pre-climactic and climactic rhyodacitic pumices varies from 80 to 330 ppm, with highest concentrations in inclusions with 4.8-5.2 wt% H2O (by FTIR). Up to 50% of the initial S may have been lost through pre-eruptive degassing at depths of 4-5 km. Ion microprobe analyses of pyrrhotite in climactic rhyodacitic tephra and andesitic scoria indicate a range in ??34S from -0.4??? to 5.8??? and from -0.1??? to 3.5???, respectively. Initial ??34S values of rhyodacitic and andesitic magmas were likely near the mantle value of 0???. Hydrogen isotope (??D) and total H2O analyses of rhyodacitic obsidian (and vitrophyre) from the climactic fall deposit yielded values ??f -103 to -53??? and 0.23-1.74 wt%, respectively. Values of

  13. The Quaternary volcanic rocks of the northern Afar Depression (northern Ethiopia): Perspectives on petrology, geochemistry, and tectonics

    Science.gov (United States)

    Hagos, Miruts; Koeberl, Christian; van Wyk de Vries, Benjamin

    2016-05-01

    The northern Afar Depression is one of the most volcano-tectonically active parts of the East African Rift system, a place where oceanic rifting may be beginning to form an incipient oceanic crust. In its center, over an area that is ∼80 km long and ∼50 km wide, there are seven major NNW-SSE-aligned shield volcanoes/volcanic edifices surrounded by compositionally distinct fissure-fed basalts. The Quaternary lavas in this area range from transitional to tholeiitic basalts, with significant across-axis variation both in mineralogy and chemistry. The variation in the contents of the major elements (TiO2, Al2O3, and Fe2O3), incompatible trace elements (Nd, Hf, Th, Ta), and the contents and ratios of the rare earth elements (REE) (e.g., (La/Yb)n = 5.3-8.9) indicate some variation in the petrogenetic processes responsible for the formation of these basalts. However, the variation in isotopic compositions of the mafic lavas is minimal (87Sr/86Sr = 0.7036-0.7041, 143Nd/144Nd = 0.51286-0.51289), which suggests only one source for all the Danakil Depression basalts. These basalts have isotope and incompatible trace element ratios that overlap with those of the Oligocene High-Ti2 flood basalts from the Ethiopian Plateau, interpreted as being derived from the last phase/tail of the Afar mantle plume source. Moreover, the Ce/Pb, Ba/U ratios indicate that the involvement of continental crust in the petrogenesis of the basaltic rocks is minimal; instead, both depth and degree of melting of the source reservoir underneath the northern Afar Depression played a major role for the production of incompatible element-enriched basalts (e.g., AleBagu Shield basalts) and the incompatible element-depleted tholeiitic basalts (e.g., Erta'Ale and Alu Shield basalts).

  14. STUDY ON RIVER-SEA INTERACTION AND FORMATION OF PALEO-YANGTZE GRAND DELTA SYSTEM IN THE AREA OF SOUTH YELLOW SEA AND EAST CHINA SEA%河海交互作用与黄东海域古扬子大三角洲体系研究

    Institute of Scientific and Technical Information of China (English)

    王颖; 邹欣庆; 殷勇; 张永战; 刘绍文

    2012-01-01

    海疆权益维护提供重要的科学依据.%China seas are characterized by river-sea interaction and accumulative continental shelf. With the association of arc islands,there is a set of marginal seas developed along China coastal areas. To carry huge amount of sediments, five of seven large rivers origin from Qinghai-Tibet Plateau ultimately flow into China seas. With sufficient sediments supply,a wide accumulative continental shelf was formed during Cenozoic era. This paper studies geomorphologic formation of the continental shelf in South Yellow Sea and East China Sea, where sediment discharge from the Yellow River and the Changjiang River are the major sources in contributing terrigenous deposits. According to the researches conducted in the last 3 decades,it is eventually realized that,there is a grand delta system distributed in the South Yellow Sea and East China Sea. The base of the system was an original delta, located between 34°30'N to 26°N from north to south,and eastward boundaried as -100~-150m water depth,with the Changjiang River mouth and Hangzhou Estuary as it's centre, forward to sea as a 230° arc shaped delta deposited on the sea bottom. The base delta was formed during Mid-Late Pleistocene when ancient Changjiang River started to run into the Yellow Sea and the East China Sea. This bottom delta was originating from the huge river sediments, discharged from ancient Changjiang and Yellow River, and being reshaped by waves and tidal currents. Upon the huge bottom delta, there are four delta unions superimposed on the top,and developed in different geological time: Paleo Changjiang-Yellow River delta and radiative sand ridge field of Late Pleistocene, Holocene-Modern Changjiang River delta and abandoned Yellow River delta of historical time. The Paleo-Yangtze Grand Delta System geographically covers most areas of East China Sea and South Yellow Sea, which forms continental sedimentary geomorphology. A multidimensional survey to this region is

  15. Adiabat_1ph 3.0 and the MAGMA website: educational and research tools for studying the petrology and geochemistry of plate margins

    Science.gov (United States)

    Antoshechkina, P. M.; Asimow, P. D.

    2010-12-01

    Adiabat_1ph is a menu-driven front-end to the MELTS, pMELTS and pHMELTS models of thermodynamic equilibrium in silicate systems. Its public release in late 2004 was described in a software brief in G3 (doi:10.1029/2004GC000816). The software package is available for Windows, MacOS X, and Linux and includes Perl scripts that, if desired, will allow almost complete automation of the calculation process. Adiabat_1ph 3.0 is scheduled for release in October 2010 and includes, for the first time, an option to double-click the run_adiabat.command script and to drag and drop file names from a browser (e.g. Explorer on Windows, Finder on Mac). This alternative mode of operation is particularly suited for teaching at undergraduate and graduate levels, as well as for quick, ad hoc, calculations for research purposes. The original method of invoking the program from the command line is retained for more intensive applications. Version 3.0 is the first to specifically target the Windows 7 and Snow Leopard platforms. The release also includes new features that are relevant to the study of plate margins. The Marianas Trough forms the southern part of the Izu-Bonin-Marianas (IBM) arc system, one of the chosen areas of focus for the MARGINS Subduction Factory initiative. Attempts to model the complicated hydrous fractionation trends observed in this region were the motivation for adding modified versions of the ‘reverse-fractionation’ and ‘amoeba’ routines (see doi:10.1016/S0012-821X(04)00058-5) into adiabat_1ph. The ‘amoeba’ scheme, which varies a trial parental melt composition until forward fractionation yields a specified target composition, has been extended so the best-fit liquid line of descent of a group of samples can be found. We have tested the adiabat_1ph versions using glass compositions from the 9N area of the East Pacific Rise and melt inclusions from the Siqueiros Fracture Zone (see Antoshechkina et al., this meeting). One of the first user requested

  16. Islamist Extremism in East Africa

    Science.gov (United States)

    2016-08-01

    relations, and disregards many basic human rights , particularly for women. While Wahhabism does not on principle denounce other faiths, many Wahhabi...Islamic Foundation, for example, which had a large presence in refugee camps and supported many madrassas in East Africa, including some linked to Ansaar...often have poorly defined property rights , hindering economic opportunities and paving the way for occasional land seizures by the government or large

  17. The East Anglian Eye Bank.

    Science.gov (United States)

    Knights, P

    1991-07-01

    The first Corneal Bank in East Anglia is located at the BUPA Hospital in Norwich, a joint venture between NHS, BUPA and the Lions Clubs International (District 101 EA). There was insufficient space to accommodate the Bank at the West Norwich Hospital where the Ophthalmic Department is situated and so, at the suggestion of the BUPA Hospital Manager, Mr Paul Hanke, It came to the BUPA Colney Lane site.

  18. Alisitos Formation, calcareous facies: Early Cretaceous episode of tectonic calm

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Vidal, F.

    1986-07-01

    The Alisitos Formation (Aptian-Albian), shaped as a marine volcanic arc, crops out along the western side of the peninsula of Baja California bounding the Peninsular Range batholith. Lithologically, this formation is formed by volcanic-breccias, porphyritic flows, biohermal limestones, and tuffaceous and pyroclastic sediments. The distribution of the different facies depends on the nature of volcanism and the distance from a volcanic center, although the presence of massive biohermal limestone indicates that in the Early Cretaceous (during the tectonic episodes), the volcanic activity decreased to the level that the environmental conditions were favorable for the development of an organic reef barrier, behind an island arc. Such conditions existed south of the Agua Blanca fault and extended to El Arco, Baja California. Based upon field observations and petrological analysis of the Alisitos limestone, an attempt is made to recreate the environmental condition in the Punta China and San Fernando, Baja California, sites.

  19. Study on Petrological Characteristics and Cycle of Volcano Rocks in Qingshuigou Area of Western Qilian Mountain%西祁连清水沟地区火山岩岩石学特征及旋回研究

    Institute of Scientific and Technical Information of China (English)

    李国涛; 孙丽莎; 翟孝志; 孙晓亮; 吴洪彬

    2016-01-01

    Cambrian volcano rocks in Dangjinshan Qingshuigou area in western Qilian mountain developed in vol⁃cano rock group in Cambrian Lapeiquan group. Distribution characteristics of the volcano rock and petrological char⁃acteristics have been studied and divided into 3 types of volcano rock facies, such as eruption facies, sedimentary facies and effusive facies. Volcano eruption cycles have been studied as well. The formation evolution characteristics in Dangjinshan area has been revealed. It has a certain guiding significance for the comparison of volcanic rock are⁃as and the recovery of volcanic mechanism.%西祁连当金山清水沟一带的寒武纪火山岩发育在寒武纪拉配泉岩群火山岩组。对该火山岩分布特征和岩石学特征进行了研究,划分了3类火山岩岩相:爆发相、沉积相、喷溢相,并对火山岩喷发旋回进行了研究,揭示了当金山地区地层演化特征,对火山岩区域对比及火山机构恢复具有一定的指导意义。

  20. Seroprevalence of Toxocariasis in Children in East- Azerbaijan Province, Iran

    Directory of Open Access Journals (Sweden)

    Yagoob Garedaghi

    2013-08-01

    Full Text Available Purpose: Toxocariasis is a zoonotic disease caused by the ascarid of dogs and cats, the main representative of which is a Toxocara canis. Distribution of the disease is world wide and is more prevalent in children. The present study was carried out in children of East Azerbaijan Province, Iran, to determine the toxocariasis seropositivity. Material and Methods: For the present seroepidemiological study, blood samples were collected at random from children of all the five districts of the East Azerbaijan Province. A total of 336 children, 187 males and 149 females in age group of 0-15 years were selected for the present study. ELISA was used for detection of IgG antibodies against Toxocara excretory secretary antigen. A questionnaire interview was conducted to obtain the data concerning their age, sex and habits. The particular points in the questionnaire asked were recorded on the format right on the spot. Results: Gender was found to be a significant risk factor for the Toxocara infection in children population. Male children were found more infected (41.71% as compared to females (24.16%. The total seroprevalence of T. canis antibodies in children of East Azerbaijan Province was 29.46 %. The risk factors that were found associated with the infection of toxocariasis in children population of East Azerbaijan Province include family back ground, status of living conditions, awareness, etc. Conclusion: The present study reveals high prevalence of T. canis infection in children of East Azerbaijan Province. It is important to raise the awareness of health professionals, public and educators to the fact that toxocariasis is a public health problem. Health promotion by means of a school based educational approach, diagnosis and continuous programme of treatment are necessary. [Cukurova Med J 2013; 38(4.000: 581-586

  1. Snake perturbation during pellet injection in the EAST tokamak

    Science.gov (United States)

    Yao, Xingjia; Hu, Jiansheng; Xu, Liqing; Xu, Zong; Chen, Yue; Li, Changzheng; Liu, Haiqing; Zhao, Hailing; Duan, Yanmin; Shi, Tonghui; Shen, Wei; EAST Team

    2016-11-01

    The pellet-induced snake oscillation was observed by soft x-ray (SXR) diagnostic in EAST for the first time after a fueling-sized pellet penetrated the q  =  1 surface. The snake phenomenon has a long lifetime with a helicity of m  =  1 and n  =  1. Basic behaviors of the snake, including the triggering condition, interaction with the sawtooth and snake rotation frequency, were discussed in detail by multiple core diagnostics. The snake location was also analyzed through observation of the vertical SXR arrays and raw SXR brightness profiles. It is clear that the snake resided in a broad region between the magnetic axis and the q  =  1 surface derived from equilibrium reconstruction. This investigation is beneficial for the understanding of the snake formation for EAST and future devices, like ITER and DEMO.

  2. Mineralogy, petrology and whole-rock chemistry data compilation for selected samples of Yucca Mountain tuffs; Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, J.R. [New Mexico Univ., Albuquerque, NM (United States)

    1991-12-01

    Petrologic, bulk chemical, and mineralogic data are presented for 49 samples of tuffaceous rocks from core holes USW G-1 and UE-25a{number_sign}1 at Yucca Mountain, Nevada. Included, in descending stratigraphic order, are 11 samples from the Topopah Spring Member of the Paintbrush Tuff, 12 samples from the Tuffaceous Beds of Calico Hills, 3 samples from the Prow Pass Member of the Crater Flat Tuff, 20 samples from the Bullfrog Member of the Crater Flat Tuff and 3 samples from the Tram Member of the Crater Flat Tuff. The suite of samples contains a wide variety of petrologic types, including zeolitized, glassy, and devitrified tuffs. Data vary considerably between groups of samples, and include thin section descriptions (some with modal analyses for which uncertainties are estimated), electron microprobe analyses of mineral phases and matrix, mineral identifications by X-ray diffraction, and major element analyses with uncertainty estimates.

  3. Searching for nonlocal lithologies in the Apollo 12 regolith: a geochemical and petrological study of basaltic coarse fines from the Apollo lunar soil sample 12023,155

    OpenAIRE

    Alexander, Louise; Snape, Joshua F.; Crawford, Ian; Joy, K. H.; Downes, Hilary

    2014-01-01

    New data from a petrological and geochemical examination of 12 coarse basaltic fines from the Apollo 12 soil sample 12023,155 provide evidence of additional geochemical diversity at the landing site. In addition to the bulk chemical composition, major, minor, and trace element analyses of mineral phases are employed to ascertain how these samples relate to the Apollo 12 lithological basalt groups, thereby overcoming the problems of representativeness of small samples. All of the samples studi...

  4. Petrology and geochemistray of Imam-Zadeh Hashem mafic and ultramafic bodies, southern Guilan province

    Directory of Open Access Journals (Sweden)

    Mojgan Salavati

    2013-04-01

    Full Text Available Mafic and ultramafic plutonic igneous bodies, with small and big outcrops, between Shemshak rock units (Jurassic are observed in east of Imam Zadeh Hashem, in southern Guilan province. Ultramafic cumulates consist of clinopyroxenite, and plagiofer clinopyroxenite, olivine clinopyroxenite, and mafic rocks, based on mineralogy consist of gabbros, olivine gabbros, biotite gabbros and amphibole gabbros. According to geochemical data, studied rocks have tholeiitic nature and in the tectonic setting diagrams, display arc characteristic. The chondrite normalized REE patterns show low enrichment in LREEs relative to HREEs. The negative Nb and Ti anomalies in primitive mantle and MORB-normalized multi-element diagrams of the rocks are characteristic of island arc magmas. Also, enrichment in LILE and depletion of HFSE may indicate a subduction-related tectonic setting. According to geological and geochemical evidence, Imam-Zadeh Hashem ultramafic and sub-alkaline gabbro rocks can be as a part of the Southern Caspian Sea Ophiolite sequence (SCO that formed in a suprasubduction tectonic system.

  5. Subduction metamorphism in the Himalayan ultrahigh-pressure Tso Morari massif: An integrated geodynamic and petrological modelling approach

    Science.gov (United States)

    Palin, Richard M.; Reuber, Georg S.; White, Richard W.; Kaus, Boris J. P.; Weller, Owen M.

    2017-06-01

    The Tso Morari massif is one of only two regions where ultrahigh-pressure (UHP) metamorphism of subducted crust has been documented in the Himalayan Range. The tectonic evolution of the massif is enigmatic, as reported pressure estimates for peak metamorphism vary from ∼2.4 GPa to ∼4.8 GPa. This uncertainty is problematic for constructing large-scale numerical models of the early stages of India-Asia collision. To address this, we provide new constraints on the tectonothermal evolution of the massif via a combined geodynamic and petrological forward-modelling approach. A prograde-to-peak pressure-temperature-time (P-T-t) path has been derived from thermomechanical simulations tailored for Eocene subduction in the northwestern Himalaya. Phase equilibrium modelling performed along this P-T path has described the petrological evolution of felsic and mafic components of the massif crust, and shows that differences in their fluid contents would have controlled the degree of metamorphic phase transformation in each during subduction. Our model predicts that peak P-T conditions of ∼2.6-2.8 GPa and ∼600-620 ∘C, representative of 90-100 km depth (assuming lithostatic pressure), could have been reached just ∼3 Myr after the onset of subduction of continental crust. This P-T path and subduction duration correlate well with constraints reported for similar UHP eclogite in the Kaghan Valley, Pakistan Himalaya, suggesting that the northwest Himalaya contains dismembered remnants of what may have been a ∼400-km-long UHP terrane comparable in size to the Western Gneiss Region, Norway, and the Dabie-Sulu belt, China. A maximum overpressure of ∼0.5 GPa was calculated in our simulations for a homogeneous crust, although small-scale mechanical heterogeneities may produce overpressures that are larger in magnitude. Nonetheless, the extremely high pressures for peak metamorphism reported by some workers (up to 4.8 GPa) are unreliable owing to conventional thermobarometry

  6. Magnetic petrology of ultramafic rocks and metabasites along the Lanterman-Mariner suture (Northern Victoria Land, Antarctica)

    Science.gov (United States)

    Strada, Eleonora; Lurcock, Pontus Conrad; Palmeri, Rosaria; Florindo, Fabio; Talarico, Franco Maria

    2016-04-01

    This study focuses on the integration between rock magnetism and metamorphic petrology of ultramafic rocks and metabasites, variably metamorphosed under UHP, eclogite or HP amphibolite facies peak conditions, and cropping out along the Lanterman-Mariner suture (Northern Victoria Land, Antarctica) in three different areas: the Lanterman Range, the Salamander Range and the Dessent Ridge. The outcrops along the Lanterman-Mariner suture provide a unique opportunity to define the relationships between magnetic properties and metamorphic evolution, in a wide P-T range, of ultramafic rocks and metabasites in the paleo-Pacific margin of Gondwana, an area which is well-studied from a petrological and structural point of view but lacking a rock magnetic study. To characterize the magnetic properties of these rocks, we performed a set of rock magnetic analyses (low-field magnetic susceptibility, natural remanence, thermomagnetic curves and hysteresis loops). We then characterized the minero-petrographical and compositional features of opaque minerals on selected samples using both the optical microscope and the Scanning Electron Microscope (SEM). The samples display a remarkable heterogeneity in the studied magnetic properties depending on both type and abundance of the carriers of magnetization (Fe-Ti oxides and sulphides). Independently of the degree of retrogression and lithology (eclogites, retrogressed eclogites, pirossenites and amphibolites), several samples contain variable amounts of both magnetite and pyrrhotite, while others show only magnetite as the main ferromagnetic mineral. The remaining samples mainly consist of paramagnetic minerals and may display small amounts of magnetite. Based on the microstructural evidence, more than one generation of ferromagnetic minerals may occur in retrogressed UHP ultramafic rocks and eclogites. These new data and interpretations are essential 1) to characterize and to verify primary and secondary oxide and sulphide

  7. Evolution of Pleistocene to Holocene eruptions in the Lesser Caucasus Mts:Insights from geology, petrology, geochemistry and geochronology

    Science.gov (United States)

    Savov, Ivan; Meliksetian, Khachatur; Connor, Charles; Karakhanian, Arkadi; Sugden, Patrick; Navasardyan, Gevorg; Halama, Ralf; Ishizuka, Osamu; Connor, Laura; Karapetian, Sergei

    2016-04-01

    Both effusive and highly explosive (VEI>5) and often voluminous caldera volcanism has developed atop the collision zone between the Arabian and the Eurasian plates. Currently what is exposed on the Anatolian-Armenian-Iranian active orogenic plateau is post-Mesozoic felsic to intermediate collision-related plutons, and mostly collision or post-collision related Quaternary volcanic structures. We have studied in detail the volcanism, tectonics and geophysics on the territory of E.Turkey and Armenia, where several large stratovolcanoes (Ararat, Lesser Ararat, Aragats, Tsghuk, Ishkhanasar) are surrounded by distinct monogenetic volcanic fields (distributed volcanism). These large in volume stratovolcanoes and the associated low volume monogenetic cones range from normal calk-alkaline to high-K shoshonitic in affinity, with their products ranging from basanites to high K trachytes and rhyolites. Several volcanic provinces, namely Kechut/Javakheti, Aragats, Gegham, Vardenis and Syunik are recognized in Armenia and each of them has > 100 mapped volcanoes. These have distinct geochemical (mineral chemistry, trace element and Sr-Nd-B isotope systematics) and petrological (melt eruption temperatures and volatile contents) fingerprints that may or may not vary over time. Age determinations and volcano-stratigraphy sections for each of the case studies we aim to present shows that the volcanism includes a continuous record from Pleistocene to Holocene, or even historical eruptions. The excellent volcano exposures and the now complete high resolution database (GIS), geological mapping, and new and improved K-Ar and Ar-Ar geochronology, uniquely allows us to evaluate the driving forces behind the volcanism in this continent-continent collision setting that is uniquely associated with long lasting eruption episodes. We shall compare the now well studied historical/Holocene eruptions with those pre-dating them, with the aim to identify possible geochemical or petrological

  8. Galaxy formation

    CERN Document Server

    Silk, Joseph; Dvorkin, Irina

    2015-01-01

    Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving our knowledge both of the cosmological parameters, of the contents of the universe, and of our origins. In these lectures intended for graduate students, galaxy formation theory is reviewed and confronted with recent observational issues. In Lecture 1, the following topics are presented: star formation considerations, including IMF, star formation efficiency and star formation rate, the origin of the galaxy luminosity function, and feedback in dwarf galaxies. In Lecture 2, we describe formation of disks and massive spheroids, including the growth of supermassive black holes, negative feedback in spheroids, the AGN-star formation connection, star formation rates at high redshift and the baryon fraction in galaxies.

  9. Mineralogy and petrology of comet 81P/wild 2 nucleus samples

    Science.gov (United States)

    Zolensky, M.E.; Zega, T.J.; Yano, H.; Wirick, S.; Westphal, A.J.; Weisberg, M.K.; Weber, I.; Warren, J.L.; Velbel, M.A.; Tsuchiyama, A.; Tsou, P.; Toppani, A.; Tomioka, N.; Tomeoka, K.; Teslich, N.; Taheri, M.; Susini, J.; Stroud, R.; Stephan, T.; Stadermann, F.J.; Snead, C.J.; Simon, S.B.; Simionovici, A.; See, T.H.; Robert, F.; Rietmeijer, F.J.M.; Rao, W.; Perronnet, M.C.; Papanastassiou, D.A.; Okudaira, K.; Ohsumi, K.; Ohnishi, I.; Nakamura-Messenger, K.; Nakamura, T.; Mostefaoui, S.; Mikouchi, T.; Meibom, A.; Matrajt, G.; Marcus, M.A.; Leroux, H.; Lemelle, L.; Le, L.; Lanzirotti, A.; Langenhorst, F.; Krot, A.N.; Keller, L.P.; Kearsley, A.T.; Joswiak, D.; Jacob, D.; Ishii, H.; Harvey, R.; Hagiya, K.; Grossman, L.; Grossman, J.H.; Graham, G.A.; Gounalle, M.; Gillet, P.; Genge, M.J.; Flynn, G.; Ferroir, T.; Fallon, S.; Ebel, D.S.; Dai, Z.R.; Cordier, P.; Clark, B.; Chi, M.; Butterworth, A.L.; Brownlee, D.E.; Bridges, J.C.; Brennan, S.; Brearley, A.; Bradley, J.P.; Bleuet, P.; Bland, P.A.; Bastien, R.

    2006-01-01

    The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.

  10. 黔东松桃南华系大塘坡组锰矿层物源:来自 Sr 同位素的证据%Provenance of Nanhuan Datangpo Formation Manganese Mn Deposit in Songtao Area,East Guizhou Province:Evidence from Sr Isotope

    Institute of Scientific and Technical Information of China (English)

    余文超; 齐靓; 杜远生; 周琦; 彭头平; 王萍; 袁良军; 徐源; 潘文; 谢小峰

    2016-01-01

    in Lower Nanhuan Datangpo Formation in Songtao,East Guizhou Province indicates that 87 Sr/86 Sr ratios in 15 samples vary in 0.705 727-0.732 536.Studied samples include Mn ore,Mn shale and black shale in the Mn-bearing layer and the highest 87 Sr/86 Sr ratio appears in the black shale sample.With Al (%)increasing in samples,87 Sr/86 Sr ratios show two changing trends:the rising trend indicates terrigenous materials input and the falling trend indicates the deep hydrothermal sources input.As to 87 Sr/86 Sr ratios via Mn (%),there is no significant correlation coefficient,but 87 Sr/86 Sr ra-tios decrease when Mn (%)increase generally,according to residual analysis,we find that this is caused by the convergence fluctuation of 87 Sr/86 Sr ratios against the Mn(%)changes.The broad variation of 87 Sr/86 Sr ratios in Mn layer is caused by the dual inputs from terrigenous materials and hydrothermal sources.Compared with the contemporary (about 660 Ma)Sr isotope ratio in paleoseawater and the Sr isotope data from different ages Mn deposit world wide,we find that the broad variation of 87 Sr/86 Sr ratios in the Datangpo For-mation.Mn layer does not conform to the feature of hydrogenetic Mn deposit.Considered with the specific geological background,we believe that the accumulation and precipitation of manganese are separated processes:the accumulation of Mn had finished in the anoxic basin during the Sturtian glaciation,whereas the Mn deposit precipitated in an unstable paleoceanographic environment at the beginning of interglaciation.

  11. East Indians in the Caribbean

    Directory of Open Access Journals (Sweden)

    Ellen M. Schnepel

    1999-07-01

    Full Text Available [First paragraph] Transients to Settlers: The Experience of Indians in Jamaica 1845-J950. VERENE SHEPHERD. Leeds, U.K.: Peepal Tree Books, 1993. 281 pp. (Paper £12.95 Survivors of Another Crossing: A History of East Indians in Trinidad, 1880-1946. MARIANNE D. SOARES RAMESAR. St. Augustine, Trinidad and Tobago: U.W.I. School of Continuing Education, 1994. xiii + 190 pp. (Paper n.p. Les Indes Antillaises: Presence et situation des communautes indiennes en milieu caribeen. ROGER TOUMSON (ed.. Paris: L'Harmattan, 1994. 264 pp. (Paper 140.00 FF Nation and Migration: The Politics of Space in the South Asian Diaspora. PETER VAN DER VEER (ed.. Philadelphia: University of Pennsylvania Press, 1995. vi + 256 pp. (Cloth US$ 39.95, Paper US$ 17.95 In the decade since 1988, Caribbean nations with Indian communities have commemorated the 150th anniversary of the arrival of East Indians to the West Indies. These celebrations are part of local revitalization movements of Indian culture and identity stretching from the French departement of Guadeloupe in the Windward Islands to Trinidad and Guyana in the south. Political changes have mirrored the cultural revival in the region. While the debate so often in the past centered on the legitimacy of East Indian claims to local nationality in these societies where African or Creole cultures dominate, in the 1990s leaders of Indian descent were elected heads of government in the two Caribbean nations with the most populous East Indian communities: Cheddi Jagan as President of Guyana in October 1992 (after a 28-year hiatus and Basdeo Panday as Prime Minister of Trinidad in November 1995. Both men have long been associated with their respective countries' struggles for economic, political, and social equality. Outside the region during the summer of 1997, fiftieth-anniversary celebrations marking the independence of India and Pakistan from Britain confirmed that Indo chic — or "Indofrenzy" as anthropologist

  12. The Middle East population puzzle.

    Science.gov (United States)

    Omran, A R; Roudi, F

    1993-07-01

    An overview is provided of Middle Eastern countries on the following topics; population change, epidemiological transition theory and 4 patterns of transition in the middle East, transition in causes of death, infant mortality declines, war mortality, fertility, family planning, age and sex composition, ethnicity, educational status, urbanization, labor force, international labor migration, refugees, Jewish immigration, families, marriage patterns, and future growth. The Middle East is geographically defined as Bahrain, Egypt, Iraq, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, United Arab Emirates, Yemen, Gaza and the West Bank, Iran, Turkey, and Israel. The Middle East's population grew very little until 1990 when the population was 43 million. Population was about doubled in the mid-1950s at 80 million. Rapid growth occurred after 1950 with declines in mortality due to widespread disease control and sanitation efforts. Countries are grouped in the following ways: persistent high fertility and declining mortality with low to medium socioeconomic conditions (Jordan, Oman, Syria, Yemen, and the West Bank and Gaza), declining fertility and mortality in intermediate socioeconomic development (Egypt, Lebanon, Turkey, and Iran), high fertility and declining mortality in high socioeconomic conditions (Bahrain, Iraq, Kuwait, Qatar, Saudi Arabia, and the United Arab Emirates), and low fertility and mortality in average socioeconomic conditions (Israel). As birth and death rates decline, there is an accompanying shift from communicable diseases to degenerative diseases and increases in life expectancy; this pattern is reflected in the available data from Egypt, Kuwait, and Israel. High infant and child mortality tends to remain a problem throughout the Middle East, with the exception of Israel and the Gulf States. War casualties are undetermined, yet have not impeded the fastest growing population growth rate in the world. The average fertility is 5 births

  13. Nature and evolution of the meteorite parent bodies: Evidence from petrology and metallurgy

    Science.gov (United States)

    Wood, J. A.

    1978-01-01

    The physical as well as chemical properties of the meteorite parent bodies are reviewed and it is concluded that many differentiated meteorites were likely formed in asteroidal-sized parents. A new model is developed for the formation of pallasites at the interface between an iron core and olivine mantle in differentiated bodies only about 10 km in diameter, which are later incorporated into a second generation of larger (100 km) parent bodies.

  14. Petrology, geochronology, geochemistry and petrogenesis of Bajestan granitoids, North of Ferdows, Khorasan Razvi Province

    Directory of Open Access Journals (Sweden)

    Reyhaneh Ahmadirouhani

    2017-02-01

    Full Text Available Introduction The investigated area is situated in the south west of the Khorasan Razavi Province along the North West of the Lut Block. Different types of metal ore bodies along with non-metal deposits have already been documented in the Lut Block (Karimpour et al., 2008. Most of the study area is covered with granitoid rocks. Metamorphic rocks with unknown age are present in the north of the area. Skarns are observed in contact with fault zones and intrusive bodies. Eocene volcanic rocks with andesite and andesibasalt composition are located in the east and north east of the area (Ahmadirouhani et al., 2015. The study area that is a part of the Lut Block has a high potentials for Cu, Fe, Au, and Barite mineralization along the observed alteration zones. In the present study, the petrography, petrogenesis, Sr–Nd isotopes, and U–Pb zircon age of acidic granitoids in the east of Bajestan were investigated. Materials and methods In the current study, 400 rock samples were collected from the field and 170 thin sections were prepared for petrography studies. Thirty samples of volcanic rocks, intrusions, and dykes were analyzed using XRF at the Geological Survey of Iran. Twenty-five samples were selected for the elemental analysis using ICP-MS by the Acme Lab Company (Canada, 16 samples of them were related to acidic intrusive bodies and dykes. In addition, zircon crystals from four samples of the granitoids bodies were collected for U–Pb dating. Approximately 50 zircon grains (i.e. euhedral, clear, uncracked crystals with no visible heritage cores and no inclusions were hand-picked from each sample. Through cathodoluminescence imaging, the internal structure and the origin of zircon grains were examined at the Geological Survey of Vienna, Austria. Moreover, zircons were dated using the (LA-ICP-MS method at the Laboratory of Geochronology, the University of Vienna, Austria using the methodology outlined in Klötzli et al., (2009. Sr and Nd

  15. Petrology and tectonic development of supracrustal sequence of Kerala Khondalite Belt, Southern India

    Science.gov (United States)

    Kumar, G. R. Ravindra; Chacko, Thomas

    1988-01-01

    The granulite terrain of southern India, of which the Kerala Khondalite belt (KKB) is a part, is unique in exposing crustal sections with arrested charnockite growth in different stages of transformation and in varied lithological association. The KKB with rocks of surficial origin and incipient charnockite development, poses several problems relating to the tectonics of burial of vast area and mechanisms involved in expelling initial H2O (causes of dryness) for granulite facies metamorphism. It is possible to infer the following sequence of events based on the field and laboratory studies: (1) derivation of protoliths of KKB from granitic uplands and deposition in fault bounded basin (cratonic rift); (2) subhorizontal deep burial of sediments; (3) intense deformation of infra and supracrustal rocks; (4) early granulite facies metamorphism predating F sub 2 - loss of primary structure in sediments and formation of charnockites from amphibole bearing gneisses and khondalites from pelites; (5) migmatisation and deformation of metasediments and gneisses; (6) second event of charnockite formation probably aided by internal CO2 build-up; and (7) isothermal uplift, entrapment of late CO2 and mixed CO2-H2O fluids, formation of second generation cordierites and cordierite symplectites.

  16. Mineralogy and Petrology of EK-459-5-1, A Type B1 CAI from Allende

    Science.gov (United States)

    Jeffcoat, C. R.; Kerekgyarto, A. G.; Lapen, T. J.; Andreasen, R.; Righter, M.; Ross, D. K.

    2015-01-01

    Calcium-aluminum-rich inclusions (CAIs) are a type of coarse-grained clast composed of Ca-, Al-, and Mg-rich silicates and oxides found in chondrite meteorites. Type B (CAIs) are exclusively found in the CV chondrite meteorites and are the most well studied type of inclusion found in chondritic meteorites. Type B1 CAIs are distinguished by a nearly monomineralic rim of melilite that surrounds an interior predominantly composed of melilite, fassaite (Ti and Al-rich clinopyroxene), anorthite, and spinel with varying amounts of other minor primary and secondary phases. The formation of Type B CAIs has received considerable attention in the course of CAI research and quantitative models, experimental results and observations from Type B inclusions remain largely in disagreement. Recent experimental results and quantitative models have shown that the formation of B1 mantles could have occurred by the evaporative loss of Si and Mg during the crystallization of these objects. However, comparative studies suggest that the lower bulk SiO2 compositions in B1s result in more prior melilite crystallization before the onset of fassaite and anorthite crystallization leading to the formation of thick melilite rich rims in B1 inclusions. Detailed petrographic and cosmochemical studies of these inclusions will further our understanding of these complex objects.

  17. Soil formation.

    NARCIS (Netherlands)

    Breemen, van N.; Buurman, P.

    1998-01-01

    Soil Formation deals with qualitative and quantitative aspects of soil formation (or pedogenesis) and the underlying chemical, biological, and physical processes. The starting point of the text is the process - and not soil classification. Effects of weathering and new formation of minerals, mobilis

  18. JPRS Report, East Asia, Southeast Asia.

    Science.gov (United States)

    2007-11-02

    volumes: China, East Europe, Soviet Union, East Asia, Near East & South Asia, Sub- Saharan Africa, Latin America , and West Europe. Supplements to...Foreign Aid, Corporate Acceptance of Land Reform Law [WEEKLY AGRIBUSINESS 18-24 Nov] ... 9 10 THAILAND Commerce Ministry Official Views...Land Reform Law 42000042 Manila WEEKLY AGRIBUSINESS in English 18-24 Nov 88 p 15 [Article under the rubric "ON THE BEAT" by Jake Espino] [Text

  19. Molecular geochemistry of Eocene Pinghu Formation coal-bearing source rocks in the Xihu Depression, East China Sea Shelf Basin%西湖凹陷始新统平湖组煤系烃源岩分子地球化学特征

    Institute of Scientific and Technical Information of China (English)

    朱扬明; 周洁; 顾圣啸; 李颖

    2012-01-01

    GC/MS analytical data of 60 saturated and aromatic fractions revealed that saturated hydrocarbons from Pinghu Formation coal-bearing source rocks in the Xihu Depression of the East China Sea Shelf Basin are characterized by abundant diterpenoid compounds originated from resins of coniferous trees and dominant Cd in steranes(>45%). Moreover, aromatic fractions are abnormally rich in terrigenous biomarkers, such as retene and 1,7-dimethylphenanthrene, indicating a predominant source of organic matter derived from terrigenous higher plants. Compared with coals and carbonaceous mudstones, dark mudstones show a relatively higher content of C27 sterane and a bimodal distribution in n-alkanes, suggesting a certain proportion of aquatic organism contributions in the organic matter source. Source rocks as a whole are believed to be deposited in an oxic limnetic-facies environment, as reflected by high Pr/Ph ratios ranging mostly from 3. 5 to 8. 5 and abundant dibenzofuranes. However, some dark mudstones show relatively lower Pr/Ph values (round 1.5), suggesting a weakly reducing to suboxic semi-deep lake setting. Coals and carbonaceous mudstones can be distinguished from dark mudstones by a higher relative concentration of C29 sterane (>80%) and lower gammacerane /C30 ho-pane ratio (<0. 05).%60个饱和烃和芳烃组分的GC-MS分析资料表明,东海盆地西湖凹陷平湖组煤系烃源岩饱和烃中富含源于针叶树脂的二萜烷类生物标志物,甾烷中普遍以C29化合物占优势(>45%),芳烃组分中惹烯、1,7-二甲基菲等陆源标志物含量异常高,这些结果反映该煤系烃源岩的成烃母质主要来源于陆源高等植物.相对于煤及碳质泥岩,暗色泥岩中C27甾烷有较高含量,且正构烷烃呈双峰型分布,说明其有机质生物源中永生生物占有一定比例.该煤系烃源岩的Pr/Ph值大多分布在3.5~8.5,二苯并呋喃类化合物较多,指示这套烃源层主要形成于氧化性较强的湖沼相

  20. Dynamic triggering of Lusi, East Java Basin

    Science.gov (United States)

    Lupi, Matteo; Saenger, Erik H.; Fuchs, Florian; Miller, Steve

    2016-04-01

    On the 27th of May 2006, a M6.3 strike slip earthquake struck beneath Yogyakarta, Java. Forty-seven hours later a mixture of mud, breccia, and gas reached the surface near Sidoarjo, 250 km far from the epicenter, creating several mud vents aligned along a NW-SE direction. The mud eruption reached a peak of 180.000 km3 of erupted material per day and it is still ongoing. The major eruption crater was named Lusi and represents the surface expression of a newborn sedimentary-hosted hydrothermal system. Lusi flooded several villages causing a loss of approximately 4 billions to Indonesia. Previous geochemical and geological data suggest that the Yogyakarta earthquake may have reactivated parts of the Watukosek fault system, a strike slip structure upon which Lusi resides. The Watukosek fault systems connects the East Java basin to the volcanic arc, which may explain the presence of both biogenic and thermogenic fluids. To quantify the effects of incoming seismic energy at Lusi we conducted a seismic wave propagation study on a geological model of Lusi's structure. A key feature of our model is a low velocity shear zone in the Kalibeng formation caused by elevated pore pressures, which is often neglected in other studies. Our analysis highlights the importance of the overall geological structure that focused the seismic energy causing elevated strain rates at depth. In particular, we show that body waves generated by the Yogyakarta earthquake may have induced liquefaction of the Kalibeng formation. As consequence, the liquefied mud injected and reactivated parts of the Watukosek fault system. Our findings are in agreement with previous studies suggesting that Lusi was an unfortunate case of dynamic triggering promoted by the Yogyakarta earthquake.

  1. 2008 East Asia Investment Forum Investment Cooperation in East Asia Facing Global Financial Fluctuations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ 2008 East Asia Investment Forum was held from May 10 to May 11 in Beijing with the theme of"Investment Cooperation in East Asia Facing Global Financial Fluctuations".It shed light on investment challenges and opportunities in Vietnam,Lao,Cambodia and Burma which are the four emerging markets in East Asia,and investment hotspots in Vietnam as well as the potential for investment cooperation in East Asia.

  2. Discovery of khondalite series from the western segment of Altyn Tagh and their petrological and geochronological studies

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The khondalite series, which are characterized by aluminum-rich gneisses (schists) consisting of sillimanite-garnet-biotite-monzonite gneiss, garnet-biotite-monzonite gneiss, graphite-sillimanite-biotite schist, and garnet-amphibole two-pyroxene granulites occurring as lenses and layers within gneisses (schists), were discovered in Tula area of western segment of Altyn Tagh. The petrology and geochemistry indicate that the protoliths of aluminum-rich gneisses (schists) are aluminum-rich pelitic and pelitic arenaceous sedimentary rocks, the protoliths of basic granulites are continental tholeiitic basalts. Therefore, the khondalite series may be produced at continental margin. They had suffered granulitic facies metamorphism with peak temperatures of 700-850℃ and pressures of 0.8-1.2 GPa. The U-Pb and Pb-Pb isotopic dating of zircons provided the ages of 447-462 Ma representing the ages of peak granulitic metamorphism. The U-Pb dating of detrital zircons from aluminum-rich gneisses yielded older upper intercept ages which reflect the times of older materials derived from source rocks of the gneiss protoliths.

  3. Discovery of khondalite series from the western segment of Altyn Tagh and their petrological and geochronological studies

    Institute of Scientific and Technical Information of China (English)

    张建新[1; 张泽明[2; 许志琴[3; 杨经绥[4; 崔军文[5

    2000-01-01

    The khondalite series, which are characterized by aluminum-rich gneisses (schists) consisting of sillimanite-garnet-biotite-monzonite gneiss, garnet-biotite-monzonite gneiss, graphite-sillimanite-biotite schist, and garnet-amphibole two-pyroxene granulites occurring as lenses and layers within gneisses (schists), were discovered in Tula area of western segment of Altyn Tagh. The petrology and geochemistry indicate that the protoliths of aluminum-rich gneisses (schists) are aluminum-rich pelitic and pelitic arenaceous sedimentary rocks, the protoliths of basic granulites are continental tholeiitic basalts. Therefore, the khondalite series may be produced at continental margin. They had suffered granulitic facies metamorphism with peak temperatures of 700-850℃ and pressures of 0.8-1.2 GPa. The U-Pb and Pb-Pb isotopic dating of zircons provided the ages of 447-462 Ma representing the ages of peak granulitic metamorphism. The U-Pb dating of detrital zircons from aluminum-rich gneisses yielded older upper i

  4. Magmatism in the Asunción-Sapucai-Villarrica Graben (Eastern Paraguay Revisited: Petrological, Geophysical, Geochemical, and Geodynamic Inferences

    Directory of Open Access Journals (Sweden)

    Piero Comin-Chiaramonti

    2013-01-01

    Full Text Available The Asunción-Sapucai-Villarrica graben (ASV in Eastern Paraguay at the westernmost part of the Paraná Basin was the site of intense magmatic activity in Mesozoic and Tertiary times. Geological, petrological, mineralogical, and geochemical results indicate that the following magmatic events are dominant in the area: (1 tholeiitic basalt and basaltic andesites, flows and sills of low- and high-titanium types; (2 K-alkaline magmatism, where two suites are distinguished, that is, basanite to phonolite and alkali basalt to trachyte and their intrusive analogues; (3 ankaratrite to phonolite with strong Na-alkaline affinity, where mantle xenoliths in ultramafic rocks are high- and low-potassium suites, respectively. The structural and geophysical data show extensional characteristics for ASV. On the whole, the geochemical features imply different mantle sources, consistently with Sr-Nd isotopes that are Rb-Nd enriched and depleted for the potassic and sodic rocks, respectively. Nd model ages suggest that some notional distinct “metasomatic events” may have occurred during Paleoproterozoic to Neoproterozoic times as precursor to the alkaline and tholeiitic magmas. It seems, therefore, that the genesis of the ASV magmatism is dominated by a lithospheric mantle, characterized by small-scale heterogeneity.

  5. Use of Potential Fields Data to Identify Petrological Controls on Seismicity within South-Central and Southeastern Alaska

    Science.gov (United States)

    Doser, D. I.; Veilleux, A. M.; Rodriguez, H.; de La Pena, A.; Mankhemthong, N.

    2010-12-01

    We have used data from regional gravity and aeromagnetic surveys to determine how variations in petrological properties of the upper plate(s) and subducting lower plate(s) influence the concentration of background seismicity in south-central and southeastern Alaska, as well as possible controls on asperities that ruptured during great earthquakes along the plate margin. In the Prince William Sound region it appears that seismicity concentrates at the edges of mafic and ultramafic bodies within the upper (North American) plate, while within Cook Inlet upper plate seismicity concentrates at the edges of a large serpentinite body. Rupture segmentation during the 1958 Fairweather earthquake in southeastern Alaska is associated with gravity highs along the Fairweather fault, while segmentation of the Queen Charlotte fault system appears related to changes in the structure of the Pacific plate. Although gravity coverage within the St. Elias region is sparse, background seismicity at depths of 10 to 20 km, including aftershocks of the 1979 Mw=7.4 St. Elias event, wraps around the edge of a gravity high located at the intersection of the Pamplona and Chugach-St. Elias fault systems. These results emphasize how additional gravity and magnetic data collection should be included as part of the upcoming Earthscope initiative in Alaska.

  6. Two episodes of subduction and collision events at the northern foot of Dabie Mountains: Evidence from petrology and structural geology of granitoid rocks

    Institute of Scientific and Technical Information of China (English)

    YANG; Kunguang; (

    2001-01-01

    preferred orientation of experimentally deformed quartzites, Geol. Soc. Am. Bull., 1973, 8: 297.[13]Ramsay, J. G., Huber, M., The Techniques of Modern Structural Geology, Vol. 1, Strain Analysis, New York: Academic Press, 1983, 73-124.[14]Li Shuguang, Ge Ningjie, Liu Deliang et al., The Sm-Nd isotopic age of C-type eclogite from the Dabie group in the northern Dabie mountains and its tectonic implication, Chinese Science Bulletin, 1989, 34(19): 1625.[15]Ye Bodan, Jian Ping, Xu Junwen et al., The Sujiahe Terrene Collage Belt and Its Constitution and Evolution Along the North Hillslope of the Tongbai-Dabie Orogenic Belt (in Chinese), Wuhan: China University of Geosciences Press, 1993, 1-69.[16]Jian Ping, Yan Weiran, Li Zhchang et al., Isotopic geochronological evidence for the Caledonian Xiongdian eclogite in the western Dabie mountains, China, Acta Geologica Sinica (in Chinese), 1997, 71(2): 133.[17]Liu Zhigang, Niu Baogui, Fu Yunlian et al., The tectonostratigraphic units at the northern foot of the Dabie mountains, Regional Geology of China (in Chinese), 1994, 13(1): 246.[18]Zhai Xiaoming, Day, H. W., Hacker, B. R. et al., Paleozoic metamorphism in the Qinling orogen, Tongbai Mountain, central China, Geology, 1998, 26: 371.[19]Li, S., Jagoutz., E., Xiao, Y. et al., Chronology of ultrahigh-pressure metamorphism in the Dabie Mountains and Su-Lu terrene: I. Sm-Nd isotope system, Science in China, Ser. D, 1996, 39(6): 597.[20]Zhang, Z., You, Z., Han, Y. et al., Petrology metamorphic process and genesis of the Dabie-Sulu eclogite belt, east-central China, Acta Geologica Sinica, 1995, 96(2): 306.[21]Cong Bolin, Wang Qingchen, The Dabie-Sulu UHP rocks belt: review and prospect, Chinese Science Bulletin, 1999, 44(12): 1074.[22]Xu Shutong, Jiang laili, Liu Yican et al., Tectonic framework and evolution of the Dabie mountains in Anhui, eastern China, Acta Geologica Sinica (in Chinese), 1992, 66(1): 1.[23]Ren Jishun, Niu Baogui, Liu Zhigang

  7. Petrologic and petrographic variation of youthful eruptive products in the Tuxtla Volcanic Field, Veracruz, Mexico

    Science.gov (United States)

    Parrish, C. B.; Kobs Nawotniak, S. E.; Fredrick, K. C.; Espindola, J.

    2010-12-01

    The Tuxtla Volcanic Field (TVF) is located near the Gulf of Mexico in the southern part of the state of Veracruz, Mexico. Volcanism in the region began around 7 Ma and has continued until recent times with the volcano San Martín Tuxtla’s latest eruptions in AD 1664 and 1793. The TVF rocks are mainly of alkaline composition and have been divided into two separate volcanic series, an older and younger. The TVF is a structural high located between the Veracruz Basin to the southwest and the Gulf of Mexico to the northeast, characterized by relatively thin crust with the depth to the Moho around 28 to 34 km. The TVF is unique because it is isolated from the nearest volcanic fields (the Mexican Volcanic Belt, Central American Volcanic Belt and the Eastern Alkaline Province) by at least 230km and because of the on-going debate over its magmatic origin. Many models have been proposed to explain the TVF’s alkaline nature in a unique location with most linking it either to the subduction of the Cocos plate to the west of Mexico and/or to extensional faulting in the region. The purpose of our study was to determine systematic changes in the youthful volcanic deposits across the TVF. Regional and local mapping was conducted and lava and scoria samples were collected from seven sites associated with two vent clusters in the TVF. Mapping of the easternmost cluster of deposits suggests chronological emplacement of the deposits through superposition and vent location and morphology. The petrography of lava and tephra deposits may further indicate magmatic origins and other factors influencing the development of the field, including chronology and possible mixing and/or differentiation. Previous published studies analyzed samples near the San Martin Tuxtla volcanic center. Their data is used as a comparative reference for these samples, most of which were collected from another, younger cluster east of Laguna Catemaco. From this study, a better understanding of past eruptive

  8. Regional economic integration in Great East Asia: determinants and barriers

    Directory of Open Access Journals (Sweden)

    Volodymyr Korol

    2015-06-01

    Full Text Available The article studies both general trends and peculiar characteristics of processes of economic integration in the Great East Asia, which plays the role of one of the major centers of contemporary global development. The basic determinants and barriers for implementation of regional strategies by China, Japan, ASEAN that will influence the geo-economic policy of Ukraine not only in East Asian, but also European and Eurasian areas. Attention is focused on the basic principles of realized and potential future integration models in the "ASEAN+" format with variable composition of member states that correspond to different extents to strategic objectives of both specified key actors in the region and extra-regional states that have global and transnational interests. Extrapolation of dominant trends in the nature and dynamics of transformation processes of East Asian economic regionalization allowed forming a forecast for the longterm conservation of importance of free trade agreements in the absence of preconditions to create customs unions. At the same time it was stressed out that proper assurance of national interests of international economic relations will be based on contractual instruments at the international level, without creating institutional and legal superstructure similar to the European Union or the Eurasian Economic Union as supranational law and supranational bodies.

  9. Sedimentary basins and petroleum geology of the Middle East

    Energy Technology Data Exchange (ETDEWEB)

    Alsharahan, A.S. [Faculty of Science, UAE University, Al Ain (United Arab Emirates); Nairn, A.E.M. [eds.] [Earth Science and Resources Institute, University of South Carolina, Columbia, SC (United States)

    1997-12-31

    The wealth of petroleum has made the Middle East one of the most actively explored regions of the world. The volume of geological, geophysical and geochemical data collected by the petroleum industry in recent decades is enormous. The Middle East may be a unique region in the world where the volume of subsurface data and information exceeds that based on surface outcrop. This book reviews the tectonic and geological history of the Middle East and the regional hydrocarbon potential on a country by country basis in the context of current ideas developed through seismic and sequence stratigraphy and incorporating the ideas of global sea level change. Subsurface data have been used as much as possible to amplify the descriptions. The paleogeographic approach provides a means to view the area as a whole. While the country by country approach inevitably leads to some repetition, it enhances the value of the volume as a teaching tool and underlines some of the changing lithologies within formations carrying the same name

  10. Petrology, geochemistry and geodynamics of basic granulite from the Altay area, North Xinjiang, China.

    Science.gov (United States)

    Li, Zi-Long; Chen, Han-Lin; Yang, Shu-Feng; Dong, Chuan-Wan; Xiao, Wen-Jiao

    2004-08-01

    The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg+Fe2+), and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg+Fe2+), Al2O3 and depletion of U, Th and Rb contents. The AG has moderate SigmaREE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG may be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750 degrees C-780 degrees C and 0.6-0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.

  11. Petrology, geochemistry and geodynamics of basic granulite from the Altay area, North Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    厉子龙; 陈汉林; 杨树锋; 董传万; 肖文交

    2004-01-01

    The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg+Fe2+),and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg+Fe2+), Al2O3 and depletion of U, Th and Rb contents. The AG has moderate ∑REE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG -05 be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750 ℃-780 ℃ and 0.6-0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.

  12. Petrology, geochemistry and geodynamics of basic granulite from the Altay area, North Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    厉子龙; 陈汉林; 杨树锋; 董传万; 肖文交

    2004-01-01

    The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg+Fe2+),and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg+Fe2+), Al2O3 and depletion of U, Th and Rbcontents. The AG has moderate ∑REE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG may be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750℃-780℃ and 0.6-0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.

  13. PETROCHINA WEST EAST GAS PIPELINE & SALES COMPANY

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ PetroChina West East Gas Pipeline & Sales Company, a regional company directly under PetroChina Company Limited (PetroChina), is responsible for the construction and operation of the West-East Gas Pipeline Project, and the gas marketing and sales of the natural gas market in China.

  14. East German Teacher Reactions to Reunification.

    Science.gov (United States)

    Hildebrand, Robert F.

    1996-01-01

    Maintains that reunification allowed teacher unions of the former West Germany to move into the former East Germany, filling a structural void left by the dissolution of the Communist Party. Specifically examines the reactions of newly elected teacher union leaders from the former East Germany to subsequent events in the education and political…

  15. Massive job cuts threaten East German science

    CERN Multimedia

    Hamer, M

    1990-01-01

    German reunification could result in thousands of scientists losing their jobs. At the end of this year the East German state budget for science will run out. Scientists in the East are keen to find Western support to protect their research (1 page).

  16. Green chemistry education in the Middle East

    Science.gov (United States)

    Kolopajlo, Larry

    2017-06-01

    The Middle East once dominated the age of alchemy, and today it is experiencing a resurgence by transforming the age of petroleum chemicals into a greener science through Estidama. This green conversion is taking place through green chemical research and education. This report examines and reviews the understudied subject of green chemical education in the Middle East through the lens of context and history.

  17. Geología y petrología del cuerpo Máfico-Ultramáfico Las Juntas, Sierra de Valle Fértil, Provincia de San Juan Geology and petrology of mafic-ultramafic body from Las Juntas, Valle Fértil, San Juan

    Directory of Open Access Journals (Sweden)

    Baliani Ignacio

    2012-03-01

    Full Text Available En el centro de la sierra de Valle Fértil aflora un cuerpo lenticular orientado en forma aproximada N-S que se encuentra encajado en un basamento ígneo de naturaleza máfica-ultramáfica. La morfología y posición actual de dicho cuerpo se debe a su emplazamiento tectónico, y la fábrica magmàtica interna presenta rumbo similar al del cuerpo y buzante al este. Las rocas que conforman el cuerpo de Las Juntas exponen una variedad litológica con las siguientes composiciones: norita olivínica, gabro anfibólico, dunita, gabronorita anfibólica y peridotita anfibólica piroxénica. Se caracterizan por presentar un encapado ígneo a escala de afloramiento y textura cumular a escala de muestra de mano, mientras que la microtextura predominante en estas rocas es de tipo coronítica. La relación cogenética entre las rocas máficas y ultramáficas de Las Juntas es determinada por la composición de silicatos de Mg y Fe presentes en ellas. El coeficiente de intercambio Fe-Mg entre olivino y clinopiroxeno con el líquido muestra un magma con una relación de #Mg (Mg/Mg + Fe-2 alrededor de 0,6; siendo inferior a la esperada para magmas generados en el manto peridotítico. Esto demuestra que el magma formador de estas rocas se habría originado en el manto litosférico, posteriormente ascendido y emplazado en niveles inferiores de la corteza (20 - 25 km. Este proceso petrológico es característico de magmatismo asociado a subducción, y relacionado al arco magmático Famatiniano.An elongate body of mafic and ultramafic plutonic rock crops out in central Sierra de Valle Fértil. The igneous body was tectonically emplaced and its internal magmatic fabrics strike roughly north-south and dip to the east. Rocks in the body are different from their hosting plutonic rocks in showing a layered igneous structure associated with pristine cumulate textural features at all observational scales. The layered body is composed of gabbronorite cumulates, ultramafic

  18. Early Earth melt production in a subduction zone, a petrological model

    Science.gov (United States)

    Magni, V.; Bouilhol, P.; Van Hunen, J.; Moyen, J.

    2013-12-01

    A large part of the Archean continental crust is made of a composite rock assemblage dominated by granitoids belonging to the TTG series (tonalite-trondhejmeite-granodiorite). The modus operandi of this sodic granitoids still disputed. If the modern processes leading to continental crust formation at convergent margins are well constrained, the extrapolation to early Earth conditions is hazardous, because the composition of Earth's early crust can be achieved through several processes. However, an 'arc' signature seems to be present in TTGs, suggesting a formation of continental crust in subduction zone settings. Moreover, they show strong similarities with modern adakites, which are thought to be formed by melting of the oceanic subducting crust. We present the results of a study where numerical models of subduction are integrated with a thermodynamic database. Our goal is to investigate under which conditions slab melting can be achieved if at all. We particularly focus our attention on the fate of water, since it is a component that is essential to the formation of TTG series, independently of the petrogenetical scenario preferred. The amount and composition of water bearing fluids in a subduction zone is controlled by slab devolatilization, and influence both the melting regime and the melt composition. Our reference model of an early Earth regime, with a high mantle potential temperature, show that the slab dehydrates early, ending up being composed of a dry eclogites. Importantly, our models show that dehydration melting is not achieved in the slab crust; yet, water-present melting of the 'dry' eclogites can be achieved if a dehydration reaction occurs in the deeper portion of the slab, fuelling the melting reaction with water. Moreover, the dehydration reactions that occurred within the slab are able to metasomatize the overlying mantle wedge, forming hydrated peridotites, that becomes a melt source when dragged down by corner-flow. Our results show the

  19. Petrological and geochemical evolution of the Tolbachik volcanic massif, Kamchatka, Russia

    Science.gov (United States)

    Churikova, Tatiana G.; Gordeychik, Boris N.; Iwamori, Hikaru; Nakamura, Hitomi; Ishizuka, Osamu; Nishizawa, Tatsuji; Haraguchi, Satoru; Miyazaki, Takashi; Vaglarov, Bogdan S.

    2015-12-01

    Data on the geology, petrography, and geochemistry of Middle-Late-Pleistocene rocks from the Tolbachik volcanic massif (Kamchatka, Klyuchevskaya group of volcanoes) are presented and compared with rocks from the neighboring Mount Povorotnaya, Klyuchevskaya group basement, and Holocene-historical Tolbachik monogenetic cones. Two volcanic series of lavas, middle-K and high-K, are found in the Tolbachik massif. The results of our data analysis and computer modeling of crystallization at different P-T-H2O-fO2 conditions allow us to reconstruct the geochemical history of the massif. The Tolbachik volcanic massif started to form earlier than 86 ka based on K-Ar dating. During the formation of the pedestal and the lower parts of the stratovolcanoes, the middle-K melts, depleted relative to NMORB, fractionated in water-rich conditions (about 3% of H2O). At the Late Pleistocene-Holocene boundary, a large fissure zone was initiated and the geodynamical regime changed. Upwelling associated with intra-arc rifting generated melting from the same mantle source that produced magmas more enriched in incompatible trace elements and subduction components; these magmas are high-K, not depleted relative to N-MORB melts with island arc signatures and rift-like characteristics. The fissure opening caused degassing during magma ascent, and the high-K melts fractionated at anhydrous conditions. These high-K rocks contributed to the formation of the upper parts of stratovolcanoes. At the beginning of Holocene, the high-K rocks became prevalent and formed cinder cones and associated lava fields along the fissure zone. However, some features, including 1975-1976 Northern Breakthrough, are represented by middle-K high-Mg rocks, suggesting that both middle-K and high-K melts still exist in the Tolbachik system. Our results show that fractional crystallization at different water conditions and a variably depleted upper mantle source are responsible for all observed variations in rocks within

  20. Petrology of Karoo volcanic rocks in the southern Lebombo monocline, Mozambique

    Science.gov (United States)

    Melluso, Leone; Cucciniello, Ciro; Petrone, Chiara M.; Lustrino, Michele; Morra, Vincenzo; Tiepolo, Massimo; Vasconcelos, Lopo

    2008-11-01

    The Karoo volcanic sequence in the southern Lebombo monocline in Mozambique contains different silicic units in the form of pyroclastic rocks, and two different basalt types. The silicic units in the lower part of the Lebombo sequence are formed by a lower unit of dacites and rhyolites (67-80 wt.% SiO 2) with high Ba (990-2500 ppm), Zr (800-1100 ppm) and Y (130-240 ppm), which are part of the Jozini-Mbuluzi Formation, followed by a second unit, interlayered with the Movene basalts, of high-SiO 2 rhyolites (76-78 wt.%; the Sica Beds Formation), with low Sr (19-54 ppm), Zr (340-480 ppm) and Ba (330-850 ppm) plus rare quartz-trachytes (64-66 wt.% SiO 2), with high Nb and Rb contents (240-250 and 370-381 ppm, respectively), and relatively low Zr (450-460 ppm). The mafic rocks found at the top of the sequence are basalts and ferrobasalts belonging to the Movene Formation. The basalts have roughly flat mantle-normalized incompatible element patterns, with abundances of the most incompatible elements not higher than 25 times primitive mantle. The ferrobasalt has TiO 2 ˜ 4.7 wt.%, Fe 2O 3t = 16 wt.%, and high Y (100 ppm), Zr (420 ppm) and Ba (1000 ppm). The Movene basalts have initial (at 180 Ma) 87Sr/ 86Sr = 0.7052-0.7054 and 143Nd/ 144Nd = 0.51232, and the Movene ferrobasalt has even lower 87Sr/ 86Sr (0.70377) and higher 143Nd/ 144Nd (0.51259). The silicic rocks show a modest range of initial Sr-( 87Sr/ 86Sr = 0.70470-0.70648) and Nd-( 143Nd/ 144Nd = 0.51223-0.51243) isotope ratios. The less evolved dacites could have been formed after crystal fractionation of oxide-rich gabbroic cumulates from mafic parental magmas, whereas the most silica-rich rhyolites could have been formed after fractional crystallization of feldspars, pyroxenes, oxides, zircon and apatite from a parental dacite magma. The composition of the Movene basalts imply different feeding systems from those of the underlying Sabie River basalts.

  1. Collieries of North East Lancashire

    Energy Technology Data Exchange (ETDEWEB)

    Nadin, J.

    2003-06-01

    The last deep mine in the Burnley Coalfield, Hapton Valley Colliery, closed in 1982 and with its demise went a comradeship and companionship that few other industries have enjoyed. The Burnley Coalfield covers an area from Colne through to Blackburn and Darwen, Higham Village to the west and Worsthorne Moor to the east. A number of pits in the Bacup area have also been included. Four companies - John Hargeaves, George Hargreaves, Brooks and Pickup and the Cliverger Coal Co. dominated coal mining in the area and between them sank the pits which many of the Burnley miners will, even now, recall. This is the story of those pits, of those who sunk and financed them, and of those who toiled, laboured, even perished, within the their depths. 200 photos.

  2. Petrologic Consequences of the Magmatic Death of a Continental Arc: Vanda Dike Swarm, Dry Valleys, Antarctica

    Science.gov (United States)

    Harpp, K. S.; Christensen, B. C.; Geist, D. J.; Garcia, M. O.

    2005-12-01

    The Dry Valleys of southern Victoria Land, Antarctica, are notable for the presence of the Vanda dikes, prominent NE-trending swarms that crosscut a sequence of granitoid plutons. These older plutons are regional in extent and comprise 3 Cambro-Ordovician groups, including: a) calc-alkaline granitoids formed at an active plate margin during the Ross Orogeny (c. 505 Ma); b) adakitic granitoids, likely marking the conclusion of Ross Orogeny subduction-related activity (c. 490 Ma); and c) younger monzonitic plutons, probably generated in an intraplate extensional setting (Cox et al., 2000). The Vanda dikes crosscut the younger plutons, possibly between c. 490 and 477 Ma (Allibone et al., 1993; Encarnacion and Grunow, 1996). Dikes from the east wall of Bull Pass and the south wall of the Wright Valley range from 0.5-25 m wide with nearly vertical dips, are usually several km long, and, in the center of the swarms, occur with a frequency of ~18 dikes/km. Most have chilled margins and are surrounded by brittle fractures, indicative of shallow intrusion into cold country rock. Dike compositions are bimodal, most defining a trend at the boundary between the high-K calc-alkaline and shoshonite series in SiO2-K2O space; some Wright Valley dikes have slightly lower K2O and are calc-alkaline. Granite porphyry dikes are relatively homogeneous (69-73 wt.% SiO2), whereas the mafic dikes exhibit a wider range of compositions (49-57 wt.% SiO2). The felsic and mafic dikes have distinct trace element abundances but similar normalized distribution patterns, including fractionated heavy rare earth elements and negative Eu and high field-strength element anomalies. Average Sr/Y ratios of both the felsic and mafic dikes cluster around 20, well below a typical adakite signature. Major and trace element variations suggest that the felsic dikes may be differentiates of the mafic magmas. Field relations further indicate that the felsic lavas may represent, on average, a later phase of dike

  3. East and Southeast Asia assessment.

    Science.gov (United States)

    Suyono, H

    1984-06-01

    The people of East and Southeast Asia, despite societal differences and varied economic successes, share 1 cultural value, i.e., the love of children and the importance of family. The small family norms espoused by family planning programs, the goal in some nations of 1- or 2-child families, the concept that 2 children are enough regardless of their sex -- all these ideas contradict the basic cultural appreciation for children in most countries and the preference for sons in many. Yet, demographic realities give Asia no alternative. It is necessary to work against cultural values to increase the opportunities for individuals, their families, their countries, and the region as a whole. All the countries of this region have had family planning programs since at least the 1970s, and some have been very successful. It may be well into the 21st century before the populations of most East and Southeast countries stabilize. Stabilization will take longer for those countries which are without successful family planning policies and programs. Each national family planning program requires the full and positive political and financial commitment of its government. Programs also need the freedom to try all new approaches. The appropriateness and acceptability of a particular mehtod should be decided by program managers and personnel in consultation with potential users, rather than by politicians. Future family planning programs will need to be even more innovative. Family planning service delivery must be brought closer to the client so it will be available in all communities and work places and at all potential public and private places. Other basic services such as nutrition, income-generating schemes, and general and maternal/child health must be integrated into the programs. The responsibility for managing programs must be assumed by the community in order to create a very strong and broad base of national commitment.

  4. East Capital suunab investorid Venemaale / Gert Tiivas ; interv. Raivo Sormunen

    Index Scriptorium Estoniae

    Tiivas, Gert, 1973-

    2007-01-01

    Rootsi investeerimispanga East Capitali Balti regiooni juht Gert Tiivas soovitab investeerida Baltimaadest suurema potentsiaaliga riikide börsidele. Vt. samas: CV: Gert Tiivas; East Capitali fondid. Diagramm: East Capitali Venemaa fondis on enim raha

  5. East Capital suunab investorid Venemaale / Gert Tiivas ; interv. Raivo Sormunen

    Index Scriptorium Estoniae

    Tiivas, Gert, 1973-

    2007-01-01

    Rootsi investeerimispanga East Capitali Balti regiooni juht Gert Tiivas soovitab investeerida Baltimaadest suurema potentsiaaliga riikide börsidele. Vt. samas: CV: Gert Tiivas; East Capitali fondid. Diagramm: East Capitali Venemaa fondis on enim raha

  6. A new tool for virtual scientific and autostereoscopic visualization of EAST

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dan, E-mail: lidan@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Xiao, B.J.; Xia, J.Y.; Wang, K.R. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); University of Science and Technology of China, Hefei, Anhui (China); Chen, S.L. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Luo, W.L. [709th Research lnstitute, China Shipbuilding lndustry Corporation, Wuhan, Hubei (China)

    2016-11-15

    Highlights: • 3D effect of the virtual EAST has been improved and data visualization has been realized in the ASEAST system. • Interaction behavior is created that the users can get information from database. • The system integrates data acquisition, data visualization and model visualization. • QT libraries are adopted to realize the cross-platform and impressive graphical interface. • In order to manage the models, the web-based model manager system is constructed. - Abstract: The Experimental Advanced Superconducting Tokamak (EAST) Device began operation in 2006. EAST visualization work has been paid more and more attention for simulating its running state and inner structure. The VEAST system had been developed to display the 3D model of EAST facility and some diagnostic data based on Java3D. Compared with the VEAST system, a new system named autosterescopic scientific EAST (ASEAST) using C/S (Client/Server) structure in combination with the technology of OpenGL and an open-source software system for 3D computer graphics and visualization called VTK (Visualization Toolkit) and the Qt5 libraries for the graphical user interface (GUI) has been developed to improve the 3D effect of the virtual EAST and visualize the experimental data. The ASEAST can be used to get access to the information of EAST and physical properties. In addition, as a general system, ASEAST supports a wide variety of 3D formats. The visualization result can be output in the corresponding format of the input. In order to improve the rendering speed, we used the classic QEM algorithm to simplify the models in preprocess stage. As for the 3D effect, we made an investigation and the survey revealed that the system had good 3D effect.

  7. Geochemical studies, magmatic evolution, microstructures and replacement mechanisms in Jebale-Barez granitoid Complex (East and Southeast Jiroft

    Directory of Open Access Journals (Sweden)

    Jamal Rasouli

    2017-08-01

    Full Text Available Introduction The Jebale-Barez Plutonic Complex (JBPC is composed of many intrusive bodies and is located in the southeastern province of Kerman on the longitude of the 57◦ 45 ' east to 58◦ 00' and Northern latitudes 28◦ 30' to 29◦ 00'. The petrologic composition is composed of granodiorite, quartzdiorite, granite, alkali-granite, and trace amounts of tonalite with dominant granodiorite composition. Previously, the JBPC was separated into three plutonic phases by Ghorbani (2014. The first plutonic phase is the main body of the complex with composition of quartz-diorite to granodiorite. After differentiation of magma in the magmatic chamber, the porphyritic and not fully consolidated magmas have intruded into the main body. Their compositions were dominantly granodiorite and granite that are defined as the second plutonic phase. Finally, the last phase was started by an intrusion of the holo- leucogranite into the previous bodies. This plutonic activity was pursued by the minor Quaternary basaltic volcanism that shows metamorphic haloes in the contacts. They are dominantly porphyric leucogranites. However, some bodies show dendritic texture that may imply the existence of silicic fluids in the latest crystallization stages. Materials and methods In this article different analysis methods were used. For example, we used a total of two hundred samples of the various granitoids that were selected for common thin section study. Forty four representative samples from the different granitic rocks were selected for whole rock chemical analyses. The analyses of both major and trace elements were performed at the Department of Earth Sciences, the University of Perugia, Italy. The analysis for all major elements was carried out by an X-ray fluorescence spectrometry (XRF using a tube completed with a Rn and W anode under conditions with acceleration voltage of 40-45 kV and electric current ranging from I=30-35 mA. After calcination of powdered

  8. Petrology and geochemistry of Late Holocene felsic magmas from Rungwe volcano (Tanzania), with implications for trachytic Rungwe Pumice eruption dynamics

    NARCIS (Netherlands)

    Fontijn, K.; Elburg, M.A.; Nikogosian, I.K.|info:eu-repo/dai/nl/323258255; van Bergen, M.J.|info:eu-repo/dai/nl/07009277X; Ernst, G.G.J.

    2013-01-01

    Rungwe in southern Tanzania is an active volcanic centre in the East African Rift System, characterised by Plinian-style explosive eruptions of metaluminous to slightly peralkaline trachytic silica-undersaturated magmas during its late Holocene history. Variations in whole-rock major and trace eleme

  9. Petrology and geochemistry of Late Holocene felsic magmas from Rungwe volcano (Tanzania), with implications for trachytic Rungwe Pumice eruption dynamics

    NARCIS (Netherlands)

    Fontijn, K.; Elburg, M.A.; Nikogosian, I.K.; van Bergen, M.J.; Ernst, G.G.J.

    2013-01-01

    Rungwe in southern Tanzania is an active volcanic centre in the East African Rift System, characterised by Plinian-style explosive eruptions of metaluminous to slightly peralkaline trachytic silica-undersaturated magmas during its late Holocene history. Variations in whole-rock major and trace eleme

  10. Gravity Investigation in Area East of River Nile (Khartoum State)

    Institute of Scientific and Technical Information of China (English)

    Eldawi M G; Farwa A G

    2003-01-01

    The purpose of the study is to investigate the subsurface geology of the area. For quantitative interpretation of the resulting Bouguer anomalies, borehole data are explored. This is done along several profiles obtained from software program G. model C version 2. 2 No. 175. This program is based on two -dimensional mass distribution. The interpretation reveals two basinal features filling depressions in the basement complex named as Abu Harira basin and Kabbashi basin. They are structurally related to Khartoum basin. As a result, a geological/structural map of the area in east of the Nile is produced. The basinal features in the study area are considered as parts of the central Sudan (Khartoum basin) that had been subjected to several tectonic events that resulted in the formation of several fracture systems associated with block subsidence and formation of these basins.

  11. Petrology of blueschist from the Western Himalaya (Ladakh, NW India): Exploring the complex behavior of a lawsonite-bearing system in a paleo-accretionary setting

    Science.gov (United States)

    Groppo, Chiara; Rolfo, Franco; Sachan, Himanshu K.; Rai, Santosh K.

    2016-05-01

    Although the Himalaya is the archetype of collisional orogens, formed as a consequence of the closure of the Neo-Tethyan ocean separating India from Asia, high-pressure metamorphic rocks are rare. Beside few eclogites, corresponding to the metamorphosed continental Indian crust dragged below Asia or underthrusted beneath southern Tibet, blueschists occur seldom along the Yarlung-Tsangpo Suture zone, i.e. the suture marking the India-Asia collision. These blueschists, mostly interpreted as related to paleo-accretionary prisms formed in response to the subduction of the Neo-Tethyan ocean below the Asian plate, are crucial for constraining the evolution of the India-Asia convergence zone during the closure of the Neo-Tethyan Ocean. In the Western Himalaya, the best occurrence of blueschist is that of the Sapi-Shergol Ophiolitic Mélange in Ladakh. This unit is dominated by volcanoclastic sequences rich in mafic material with subordinate interbedding of metasediments, characterized by very fresh lawsonite blueschist-facies assemblages. In this paper, the lawsonite blueschist-facies metasediments have been petrologically investigated with the aims of (i) constraining the P-T evolution of the Sapi-Shergol Ophiolitic Mélange, (ii) evaluating the influence of Fe2O3 and of H2O on the stability of the high-pressure mineral assemblages, (iii) understanding the processes controlling lawsonite formation and preservation, and (iv) interpreting the P-T evolution of the Sapi-Shergol blueschists in the framework of India-Asia collision. Our results indicate that (i) the Sapi-Shergol blueschists experienced a cold subduction history along a low thermal gradient, up to peak conditions of ca. 470 °C, 19 kbar; furthermore, in order to preserve lawsonite in the studied lithologies, exhumation must have been coupled with significant cooling, i.e. the resulting P-T path is characterized by a clockwise hairpin loop along low thermal gradients (< 8-9 °C/km); (ii) the presence of ferric

  12. Double seismic zone of the Nazca plate in northern Chile: High-resolution velocity structure, petrological implications, and thermomechanical modeling

    Science.gov (United States)

    Dorbath, Catherine; Gerbault, Muriel; Carlier, Gabriel; Guiraud, Michel

    2008-07-01

    This paper presents an interdisciplinary study of the northern Chile double seismic zone. First, a high-resolution velocity structure of the subducting Nazca plate has been obtained by the tomoDD double-difference tomography method. The double seismic zone (DSZ) is observed between 80 and 140 km depth, and the two seismic planes is 20 km apart. Then, the chemical and petrologic characteristics of the oceanic lithosphere associated with this DSZ are deduced by using current thermal-petrological-seismological models and are compared to pressure-temperature conditions provided by a numerical thermomechanical model. Our results agree with the common hypothesis that seismicity in both upper and lower planes is related to fluid releases associated with metamorphic dehydration reactions. In the seismic upper plane located within the upper crust, these reactions would affect material of basaltic (MORB) composition and document different metamorphic reactions occurring within high-P (>2.4 GPa) and low-T (130 km), lawsonite-amphibole eclogite conditions. The lower plane lying in the oceanic mantle can be associated with serpentinite dehydration reactions. The Vp and Vs characteristics of the region in between both planes are consistent with a partially (˜25-30 vol % antigorite, ˜0-10% vol % brucite, and ˜4-10 vol % chlorite) hydrated harzburgitic material. Discrepancies persist that we attribute to complexities inherent to heterogeneous structural compositions. While various geophysical indicators evidence particularly cold conditions in both the descending Nazca plate and the continental fore arc, thermomechanical models indicate that both seismic planes delimit the inner slab compressional zone around the 400°C (±50°C) isotherm. Lower plane earthquakes are predicted to occur in the slab's flexural neutral plane, where fluids released from surrounding metamorphic reactions could accumulate and trigger seismicity. Fluids migrating upward from the tensile zone below

  13. Petrology and geochronology of crustal xenoliths from the Bering Strait region: Linking deep and shallow processes in extending continental crust

    Science.gov (United States)

    Akinin, V.V.; Miller, E.L.; Wooden, J.L.

    2009-01-01

    Petrologic, geochemical, and metamorphic data on gneissic xenoliths derived from the middle and lower crust in the Neogene Bering Sea basalt province, coupled with U-Pb geochronology of their zircons using sensitive high-resolution ion microprobe-reverse geometry (SHRIMP-RG), yield a detailed comparison between the P-T-t and magmatic history of the lower crust and magmatic, metamorphic, and deformational history of the upper crust. Our results provide unique insights into the nature of lithospheric processes that accompany the extension of continental crust. The gneissic, mostly maficxenoliths (constituting less than two percent of the total xenolith population) from lavas in the Enmelen, RU, St. Lawrence, Nunivak, and Seward Peninsula fields most likely originated through magmatic fractionation processes with continued residence at granulite-facies conditions. Zircon single-grain ages (n ??? 125) are interpreted as both magmatic and metamorphic and are entirely Cretaceous to Paleocene in age (ca. 138-60 Ma). Their age distributions correspond to the main ages of magmatism in two belts of supracrustal volcanic and plutonic rocks in the Bering Sea region. Oscillatory-zoned igneous zircons, Late Cretaceous to Paleocene metamorphic zircons and overgrowths, and lack of any older inheritance in zircons from the xenoliths provide strong evidence for juvenile addition of material to the crust at this time. Surface exposures of Precambrian and Paleozoic rocks locally reached upper amphibolite-facies (sillimanite grade) to granulite-facies conditions within a series of extension-related metamorphic culminations or gneiss domes, which developed within the Cretaceous magmatic belt. Metamorphic gradients and inferred geotherms (??30-50 ??C/km) from both the gneiss domes and xenoliths aretoo high to be explained by crustal thickening alone. Magmatic heat input from the mantle is necessary to explain both the petrology of the magmas and elevated metamorphic temperatures. Deep

  14. A tutorial for sandstone petrology: architecture and development of an interactive program for teaching highly visual material

    Science.gov (United States)

    Choh, Suk-Joo; Milliken, Kitty L.; McBride, Earle F.

    2003-11-01

    We have developed an interactive computer-based tutorial in sandstone petrology for undergraduate-level students. The goal of this tutorial is to provide students exposure to the highly visual subject matter of petrography outside the confines of organized laboratory exercises. This paper describes the architecture and development procedures of the current version of the sandstone petrography tutorial, and offers a possible model for similar development approaches in other fields of petrography or in any other field that utilizes large quantities of visual material such as remote sensing image interpretation or seismic interpretation. The tutorial is an interactive photomicrograph archive with sufficient content and flexible architecture that functions as a virtual laboratory instructor as well as a stand-alone reference. The current tutorial was programmed using Macromedia Authorware v.6.0 and supports both Windows-based and MacOS personal computers. The tutorial is constructed around the Folk sandstone classification scheme (quartzarenite, arkose, and litharenite), and an additional section addresses grains other than quartz, feldspar, and lithic fragments and sandstones dominated by these grains. The user interface is designed to take minimal portion of the screen area so that the screen can closely mimic the type of view seen by a student peering down a microscope. Each photomicrograph in the tutorial is basically unadorned until the user actively calls up information that is temporarily displayed over the image, inducing the user to search for information and actively "ask" to be informed with a mouse click. The structure of the tutorial permits multiple strategies of program use, as a linear tutorial, tutorial driven by thumbnail browser, and as a searchable reference.

  15. Thermal structure and melting conditions in the mantle beneath the Basin and Range province from seismology and petrology

    Science.gov (United States)

    Plank, T.; Forsyth, D. W.

    2016-04-01

    To better constrain the temperature structure in the upper mantle, we jointly invert seismic surface wave velocities and basalt thermobarometry. New measurements of the water concentration (1.0-3.5 wt %) and oxygen fugacity (FMQ + 0.5 to + 1.5) of basalts from seven recently active volcanic fields in the Basin and Range province (Cima, Pisgah, Amboy, Big Pine, Black Rock, Snow Canyon, W. Grand Canyon) enable more accurate equilibration pressure (P) and temperature (T) estimates of the mantle melts. We developed a revised thermobarometer that more precisely predicts the results of laboratory experiments on melts equilibrated with olivine and orthopyroxene and accounts for the effects of water and CO2. Applying these methods to basalts from the Basin and Range we find that most equilibrated near the dry solidus in P-T space and at depths in the vicinity of the lithosphere-asthenosphere boundary (LAB) inferred from receiver function analysis and Rayleigh surface wave tomography. The wet basalts should have begun melting well below the dry solidus, so the depths of equilibration probably reflect ponding of rising melts beneath the nominally dry lithosphere. A two-parameter thermal model is sufficient to simultaneously satisfy both the seismological and petrological constraints. In the model, the depth to the dry solidus defines the bottom boundary of the conductive lid, while the potential temperature (Tp) controls the asthenosphere and LAB thermal structure. The optimum estimates of Tp range from 1500°C, and depths to the LAB range from ˜55 to 75 km, with uncertainties on the order of ±50°C and ±10 km. In contrast to standard tomographic images or basalt thermobarometry, the output of the joint inversion is a geotherm that can be tested quantitatively against other observations.

  16. THE PETROLOGY CHARACTERISTIC OF GRANITOID ROCK BASED ON GEOCHEMICAL ANALYSIS OF BAJAU CAPE COAST AND ITS SURROUNDING, WEST KALIMANTAN

    Directory of Open Access Journals (Sweden)

    Noor C.D. Aryanto

    2017-07-01

    Full Text Available The aim of this study is to identify of petrology characteristic based on geochemical analysis in order to know the granitoid rock type. Administratively, the study area is in the City and District of Singkawang, West Kalimantan Province, at coordinate 108°48'30” - 109°1'30” E and 0°40'30” - 0°54'30” N and, situated ± 145 km to the north of Pontianak City. The outcrop of granitoid along Bajau Cape coast and its surrounding, had been analyzed petrographically and geochemically using AAS method. Based on analysis of five samples show that the ratio mole of Al2O3/(CaO+Na2O +K2O > 1 ranged between 1.12 and 1.7, while the rest of three samples are moderately aluminous, with a ratio value between 0.5 and 1.0. The ratio between K2O and (K2O+Na2O+CaO ranges 0.07 to 0.55 (moderate that forms alkali feldspar normative ranges from 3.8 to 15.89 wt%. This ratio shows that granite alkali feldspar is classified to be calc-alkaline series. Petrographically, this rock is porfiritic texture, hollocrystalline, granular hypodiomorphic and biotite present as phenocryst, yellowish brown, euhedral, thin and platy. The content of oxides element (Na2O and MgO tend to decrease, whereas of other oxides elements, namely Al2O3, TiO2, K2O, FeO and CaO increased, parallel with the raising of SiO2. Therefore, the Singkawang Granitoid can be grouped as alkali feldspar granite, syeno-granite and quartz monzonite.

  17. Integrated geophysical-petrological modelling of the Trans-European Suture Zone along the TOR-profile

    Science.gov (United States)

    Pappa, Folker; Ebbing, Jörg; Rabbel, Wolfgang

    2014-05-01

    We apply the integrated geophysical-petrological software package LitMod3D to study the effect of changes in thickness and composition associated with the Sorgenfrei-Tornquist-Zone as part of the Transeuropean Suture Zone (TESZ). Results of the TOR-project (Teleseismic Tomography TORnquist) show a P wave velocity anomaly that indicates an abrupt step in the base lithosphere between southern Sweden and Northern Germany. From a depth of ~300 km beneath the proto-Proterozoic Baltic shield the base lithosphere increases to less than 100 km beneath the Phanerozoic terranes in the southwest. However, this significant change in lithospheric thickness is not expressed by significant changes in the gravity field or topography. Hence, some form of isostatic compensation must be achieved by changes in the composition or thermal structure of the crust or upper mantle. First sensitivity tests were performed to show that the most important parameters to explain seismic upper mantle velocities, gravity and topography. These are, in addition to lithospheric thickness, the densities and thermal conductivity in the crust and the amount of depletion of the subcontinental lithospheric mantle (SCLM). When applying a simple geometry with steps at the Moho and base lithosphere, the TOR results could be reproduced to a large degree when applying different compositions for the SCLM beneath the Proterozoic and Phanerozoic domains. To address the gravity field and topography as well, we present two alternative models for the TOR-profile. In the first model, the gravity field and topography is explained by dividing the Phanerozoic SCLM in a refertilized upper and more depleted lower part. This model leads to a deeper base lithosphere (130 km), but does not provide a very good fit to the P wave velocities. In the second alternative, the thermal conductivity of the Phanerozoic crust and for the sediments has been increased within reasonable parameters. This leads to a shallower LAB ~100 km and

  18. Petrological evidence for non-linear increase of magmatic intrusion rates before eruption at open vent mafic volcanoe

    Science.gov (United States)

    Ruth, D. C. S.; Costa Rodriguez, F.

    2015-12-01

    The most active volcanoes on earth erupt in a yearly to decadal time scales, typically erupt mafic magmas and are open-vent systems with prominent degassing plumes (e.g. Mayon, Arenal, Llaima, Etna). Here we investigate the plumbing systems, dynamics, and processes that drive eruptions at these systems. These are key questions for improving hazard evaluation, and better understanding the unrest associated with these types of volcanoes. The petrology and geochemistry from six historical eruptions (1947-2006) of Mayon volcano (Philippines) shows that all lavas are basaltic andesite with phenocrysts of plagioclase + orthopyroxene (Opx) + clinopyroxene. Opx crystals show a variety of compositions and zoning patterns (reverse, normal or complex) with Mg# (= 100 *Mg/[Mg+Fe]) varying from 67 to 81. The simplest interpretation is that the low Mg# parts of the crystals resided on an upper crustal and crystal rich reservoir that was intruded by more primitive magmas from which the high Mg# parts of the crystals grew. Modelling Mg-Fe diffusion in Opx shows that times since magma injection and eruption range from a few days up to 3.5 years in all of the investigated eruptions. The longest diffusion times are shorter than the repose times between the eruptions, which implies that crystal recycling between eruptive events is negligible. This is a surprising result that shows that for each eruption a different part of the evolved crystal-rich plumbing system is activated. This can be due to random intrusion location or an irreversibility of the plumbing system that prevents multiple eruptions from the same crystal-rich part. Moreover, we find that the number of intrusions markedly increases before each eruption in a non-linear manner. Such an increased rate of intrusions with time might reflect non-linear rheological properties of