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Sample records for atlantic igneous province

  1. Introduction : from the British Tertiary into the future - modern perspectives on the British Palaeogene and North Atlantic Igneous provinces.

    OpenAIRE

    Jerram, Dougal A.; Goodenough, Kathryn Mary; Troll, Valentin R.

    2009-01-01

    The study of volcanic rocks and igneous centres has long been a classic part of geological research. Despite the lack of active volcanism, the British Isles have been a key centre for the study of igneous rocks ever since ancient lava flows and excavated igneous centres were recognized there in the 18th century (Hutton, 1788). This led to some of the earliest detailed studies of petrology. The starting point for many of these studies was the British Palaeogene Igneous Province (BPIP; formerly...

  2. Assessing the volcanic styles of the North Atlantic Igneous Province and their potential implications for the PETM

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    Jerram, Dougal; Reynolds, Peter; Jones, Morgan; Svensen, Henrik; Planke, Sverre; Millett, John; Galland, Olivier; Angkasa, Syahreza; Schofield, Nick; Howell, John

    2016-04-01

    In order to understand the role that large igneous provinces play in changing climatic conditions, it is important to constrain the different styles of volcanism and their volumes, both temporally and spatially. Regional variations in palaeo-environment as well as different volcanic materials (basic-acidic) can all have effects on the eruption styles, and determine whether eruptions effectively release gases into the atmosphere and hydrosphere. The North Atlantic Igneous Province (NAIP) covers a vast area as well as a significant time span, having formed at 60-55 Ma. Importantly, its' formation is implicated in the climatic perturbations at the Palaeocene-Eocene Thermal Maximum (PETM). The products of volcanism in the NAIP range from lava flows and hyaloclastites to more explosive tephra forming eruptions from both basaltic and more evolved eruptions. The explosive end member styles of both mafic and felsic volcanism also produce ash beds in the rock record at key times. Hydrothermal vent structures which are predominantly related with the emplacement of large (>1000 km3) intrusions into the subvolcanic basins in the NAIP are another style of eruption, where climate-forcing gases can be transferred into the atmosphere and hydrosphere. In this case, the types and volumes of gas produced by intrusions is heavily dependent on the host-rock sediment properties that they intrude through. The distribution of vent structures can be shown to be widespread on both the Norwegian and the Greenland margins of the NAIP. In this overview we assess the main eruption styles, deposits and their distribution within the NAIP using mapped examples from offshore seismic data as well as outcrop analogues, highlighting the variability of these structures and their deposits. As the availability of 3D data from offshore and onshore increases, the full nature of the volcanic stratigraphy from the subvolcanic intrusive complexes, through the main eruption cycles into the piercing vent

  3. Seismic evidence for crustal underplating beneath a large igneous province: The Sierra Leone Rise, equatorial Atlantic

    OpenAIRE

    Jones, E. J. W.; McMechan, G. A.; Zeng, X.

    2015-01-01

    Wide-angle seismic profiles reveal anomalously thick crust with a high-velocity (> 7.3 km s− 1) zone under the Sierra Leone Rise, a major mid-plate elevation in the Atlantic lying between the Cape Verde platform and the Cameroon Volcanic Line. A profile recorded over the crest using an ocean-bottom seismometer and surface sonobuoys shows that beneath a 3 km water layer and 1 km of sediments, the basement extends to 16–20 km below sea level. Most velocity-depth values fall outside the expected...

  4. Some Environmental Consequences of Large Igneous Provinces

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    Coffin, M. F.

    2009-12-01

    The formation of large igneous provinces (LIPs)—continental flood basalts, ‘volcanic’ margins, and oceanic plateaus—may impact the atmosphere, oceans, and biosphere by rapidly releasing huge amounts of particulates, magmatic volatiles (CO2, SO2, Cl, F, etc.), and potentially volatiles (CO2, CH4, SO2, etc.) from intruded sediments (e.g., carbonates, organic-rich shales, evaporites). A key factor affecting the magnitude of volatile release is whether eruptions are subaerial or marine; hydrostatic pressure inhibits vesiculation and degassing of relatively soluble volatile components (H2O, S, Cl, F) in deep water submarine eruptions, although low solubility components (CO2, noble gases) are mostly degassed even at abyssal depths. Directly or indirectly, such injections may cause changes in the atmosphere/ocean system that can lead to perturbations of atmosphere/ocean chemistry, circulation, ecology, and biological productivity. These changes can be global in extent, particularly if environmental conditions were at or near a threshold state or tipping point. LIPs may have been responsible for some of the most dramatic and rapid changes in the global environment. For example, between ~145 and ~50 Ma, the global ocean was characterized by chemical and isotopic variations (especially in C and Sr isotope ratios, trace metal concentrations, and biocalcification), relatively high temperatures, high relative sea level, episodic deposition of black shales (oceanic anoxic events), high production of hydrocarbons, mass extinctions of marine organisms, and radiations of marine flora and fauna. Temporal correlations between the intense pulses of igneous activity associated with LIP formation and environmental changes suggest more than pure coincidence. The 1783-84 eruption of Laki on Iceland provides the only historical record of the type of volcanism that constructs transient LIPs. Although Laki produced a basaltic lava flow representing only ~1% of the volume of a typical

  5. Large igneous provinces (LIPs) and carbonatites

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    Ernst, Richard E.; Bell, Keith

    2010-03-01

    There is increasing evidence that many carbonatites are linked both spatially and temporally with large igneous provinces (LIPs), i.e. high volume, short duration, intraplate-type, magmatic events consisting mainly of flood basalts and their plumbing systems (of dykes, sills and layered intrusions). Examples of LIP-carbonatite associations include: i. the 66 Ma Deccan flood basalt province associated with the Amba Dongar, Sarnu-Dandali (Barmer), and Mundwara carbonatites and associated alkali rocks, ii. the 130 Ma Paraná-Etendeka (e.g. Jacupiranga, Messum); iii. the 250 Ma Siberian LIP that includes a major alkaline province, Maimecha-Kotui with numerous carbonatites, iv. the ca. 370 Ma Kola Alkaline Province coeval with basaltic magmatism widespread in parts of the East European craton, and v. the 615-555 Ma CIMP (Central Iapetus Magmatic Province) of eastern Laurentia and western Baltica. In the Superior craton, Canada, a number of carbonatites are associated with the 1114-1085 Ma Keweenawan LIP and some are coeval with the pan-Superior 1880 Ma mafic-ultramafic magmatism. In addition, the Phalaborwa and Shiel carbonatites are associated with the 2055 Ma Bushveld event of the Kaapvaal craton. The frequency of this LIP-carbonatite association suggests that LIPs and carbonatites might be considered as different evolutionary ‘pathways’ in a single magmatic process/system. The isotopic mantle components FOZO, HIMU, EM1 but not DMM, along with primitive noble gas signatures in some carbonatites, suggest a sub-lithospheric mantle source for carbonatites, consistent with a plume/asthenospheric upwelling origin proposed for many LIPs.

  6. Magmatic systems of large continental igneous province

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    Sharkov, Evgenii

    2014-05-01

    Large igneous provinces (LIPs) of the modern type are known from the middle Paleoproterozoic and have a great abundance in the Phanerozoic. The most researches considered their appearance with ascending of the mantle thermochemical superplumes which provided simultaneously eruption of the same type of lavas on the huge territories. Judging on presence among them different subprovinces, formation of concrete magmatic systems were linked with protuberances (secondary plumes) on the superplumes surfaces. We suggest that origin of such plumes was linked with local enrichment of upper part of the superplumes head beneath roofing by fluid components; it led to lowering of the plume material density and initiated ascending of the secondary plumes. As a result, their heads, where partial melting occurred, can reach the level of the upper crust as it follows from absence of lower-crustal rocks among xenoliths in basalts, although mantle xenoliths existed in them. Important feature of LIPs is presence of two major types of mafic lavas: (1) geochemical-enriched alkali Fe-Ti basalts and picrites, and (2) basalts of normal alkalinity (tholeiites) with different contents of TiO2. At that the first type of mafites are usually typical for lower parts of LIPs which initially developed as continental rifts, whereas the second type composed the upper part of the traps' cover. Magmatic systems of the LIPs are subdivided on three levels of different deep: (1) zones of magma generation, (2) areas of transitional magma chambers where large often layered intrusive bodies are formed, and (3) areas on surface where lava eruptions and subvolcanic intrusions occurred. All these levels are linked by feeder dykes. The least known element of the system is area of magma generation, and, especially, composition of melting substratum. Important information about it is contained in aforementioned mantle xenoliths in alkali basalts and basanites. They practically everywhere are represented by two

  7. Crustal architecture of a continental large igneous province

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    Minakov, Alexander; Faleide, Jan Inge; Krupnova, Natalia; Sakoulina, Tamara

    2014-05-01

    The northern Barents Sea was strongly affected by the Cretaceous High Arctic Large Igneous Province through abundant mafic intrusions, eruption of flood basalts, and regional uplift. Recently acquired geophysical data in this region provide a unique opportunity to study in detail crustal architecture of large igneous provinces. A giant dike swarm is identified based on magnetic anomalies coherent over a distance of hundreds of kilometers. Coincident ocean bottom seismometer, multichannel streamer, and gravity data indicate that the surface basalts and shallow sills were associated with feeder systems cross-cutting the entire crust. At the same time, the distribution of dikes exhibits more complex pattern than radially symmetric with respect to the presumable magmatic center in the Alpha Ridge region. Thus, the preferred orientation of dikes could be controlled by both paleostress and pre-existing weaknesses (Early-Late Paleozoic faults). The data do not indicate a thick igneous mafic lower crust while the existence of heavy ultramafic cumulates below the Moho has not been resolved yet. In view of these observations different models of magma transport and related paleo-surface topography are discussed.

  8. Large Igneous Provinces, Sulfur Aerosols, and Initiation of Snowball Earth

    Science.gov (United States)

    Macdonald, F. A.; Wordsworth, R. D.

    2015-12-01

    The events that led to the initiation of Snowball Earth remain poorly understood. Proposed scenarios include a methane addiction, a biological innovation that led to an increase in organic carbon burial and anaerobic remineralization, or an increase in global weatherability due to a paleogeography with a preponderance of low latitude continents, and the subareal implacement of large igneous provinces (LIPs) at the equator. The Franklin LIP was emplaced between 730 and 710 Ma and covers an area of over 2.25 Mkm2 with lavas, sills, and dikes extending over much of northern Laurentia from Alaska through northern Canada to Greenland and potentially to Siberia. The most precise geochronological constraints on the Franklin LIP overlap with the onset of the Sturtian Snowball Earth glaciation, which began between 717 and 716 Ma and marked the first glaciation in over 1 billion years. The Franklin LIP is the largest preserved Neoproterozoic LIP and one of the largest in Earth History. Additionally, it was emplaced at equatorial latitudes with associated sills that invaded epicontinental sulfur evaporite basins, potentially maximizing environmental effects. Here we explore the hypothesis that the Sturtian Snowball Earth was initiated in part by an increase in planetary albedo from the conversion of volcanic SO2/H2S emissions to tropospheric and stratospheric sulfate aerosols through a combination of geochemical and modeling studies.

  9. Roots of Magmatic Systems of Large Continental Igneous Provinces

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    Sharkov, E. V.

    2014-12-01

    It is consensus now that appearance of the large igneous provinces (LIP) is considered with ascending of mantle superplumes. It is evident that beneath LIPs was not exited magma oceans and adiabatic melting occurred in heads of protuberances on their surface (local, or secondary plumes), which can reach relatively shallow levels. The least known element of magmatic system is area of magma generation and meltedsources. Important information about it is contained in the mantle xenoliths in alkali basalts. They are represented by two series: (1) "green": spinel peridotite (maily lherzolite) and minor spinel pyroxenite (websterite), and (2) "black" (veins in the peridotite matrix): wehrlite, Al-Ti-augite and hornblende clinopyroxenite, hornblendite, phlogopitite, etc, which crystallized from fluid-saturated melts or high-density fluid. Very likely, that these fluids, enriched in Fe, Ti, alkalis and incompatible elements, were parts of intergranular material of original plume material and were released due to its decompression; evidently, they provided specific composition of plume-related melts. Both types of xenoliths represent material of plume head and accordingly - the melting substratum. One of problem of plume-related magmatism is coexisting of alkali and tholeiitic basalts, which origin often considered with different PT conditions. However, this situation can be explained another way. Because fluid components, acting jointly or separately, impregnated the peridotite matrix nonuniform, it led to heterogeneous composition of smelted magmas, and primary melts can have different composition even though be forming at similar PT conditions. According to Yoder and Tilley (1962), even small differences in SiO2 content lead to different ways in evolution of magmas due to critical plane of silica undersaturation. As a result, one magmas will develop to Ne enrichment (alkali basalts) and another - to silica direction (tholeiite basalts.

  10. Climate changes caused by degassing of sediments during the emplacement of large igneous provinces: REPLY

    OpenAIRE

    Ganino, Clément; Arndt, Nicholas

    2010-01-01

    Reply to Grzegorz Racki for his comment on our manuscript and for his overall support for the hypothesis that the nature of the rocks in the substrate of large igneous province has an important influence on their environmental impact (Ganino and Arndt, 2009).

  11. Identification of mantle plumes in the Emeishan Large Igneous Province

    Institute of Scientific and Technical Information of China (English)

    Yi-Gang Xu; Jifeng Xu; Yue-Jun Wang; Bin He; Xiaolong Huang; Zhenyu Luo; Sun-Lin Chung; Long Xiao; Dan Zhu; Hui Shao; Wei-Ming Fan

    2007-01-01

    @@ The plume hypothesis has been recently challengedlargely because some fundamental aspects predicted bythe modeling of plumes are found to be lacking in someclassic hotspot regions. This review paper summarizesrecent achievements made in the late Permian Emeishan continental flood basalt province in southwest China.

  12. Investigating Large Igneous Province Formation and Associated Paleoenvironmental Events: A White Paper for Scientific Drilling

    Directory of Open Access Journals (Sweden)

    Michael R. Rampino

    2008-07-01

    Full Text Available Earth’s history has been punctuated over at least the last 3.5 billion years by massive volcanism on a scale unknown in the recent geological past. Largely unknown mechanical and dynamic processes, with unclear relationships to seafloor spreading and subduction, generated voluminous, predominately mafic magmas that were emplaced into the Earth’s lithosphere. The resultant large igneous provinces (LIPs; Coffin and Eldholm, 1994; Ernst and Buchan, 2001; Bryan and Ernst, 2008 were at times accompanied by catastrophic environmental changes. The interaction of the LIP-associated mantle processes with the Earth’s crust have produced a variety of surface expressions (Fig. 1a and 1b; the most common present-day examples are oceanic plateaus (e.g., Kerguelen/Broken Ridge, Ontong Java, Manihiki, Hikurangi, Shatsky, ocean basin flood basalts (e.g., Caribbean, Nauru, magma-dominated divergent continental margins (e.g., theNorth Atlantic, and continental flood basalts (e.g., Columbia River, Deccan Traps, Siberian Traps. Environmental effects associated with LIP formation include climate changes, mass and other extinctions, variations in ocean and atmospheric chemistry, and Oceanic Anoxic Events (OAEs. Therefore, the geodynamic processes in the mantle that produce LIPs have potentially profoundly affected the Earth’s environment, particularly the biosphere and climate. The IntegratedOcean Drilling Program (IODP affords unique opportunities to investigate LIPs and associated environmental effects, building upon results from the Ocean Drilling Program (ODP and Deep Sea Drilling Project (DSDP (Coffin et al., 2006. To this end, a workshop on LIPs, sponsored by IODP Management International (IODP-MI and the Consortium for Ocean Leadership, was held at the University of Ulster in Coleraine, Northern Ireland, U.K. on 22–25 July 2007 (Coffinet al., 2007.

  13. Tectonic provinces of the Atlantic Ocean

    Science.gov (United States)

    Pushcharovsky, Yu. M.

    2009-05-01

    The tectonic structure of the floor of the Atlantic Ocean beyond the continental margins is insufficiently studied. This is also true of its tectonic demarcation. The segmentation of the floor into regional-scale tectonic provinces of several orders proposed in this paper is primarily based on structural and historical geological features. It is shown that deep oceanic basins and fault tectonics are of particular importance in this respect. Tectonic provinces of two orders are distinguished by a set of attributes. The first-order provinces are the North, Central, South, and Antarctic domains of the Atlantic Ocean. They are separated by wide demarcation fracture zones into Transatlantic (transverse) second-order tectonic provinces. Ten such provinces are recognized (from the north southward): Greenland-Lofoten, Greenland-Scandinavia, Greenland-Ireland, Newfoundland-European, North American-African, Antilles-African, Angola-Brazil, Cape-Argentine, North Antarctic, and South Antarctic. This subdivision demonstrates significant differentiation in the geodynamic state of the oceanic lithosphere that determines nonuniform ocean formation and the tectonic features of the ocean floor. The latitudinal orientation of the second-order provinces inherits the past tectonic pattern, though newly formed structural units cannot be ruled out. The Earth rotation exerts a crucial effect on the crust and the mantle.

  14. Lithospheric mantle evolution monitored by overlapping large igneous provinces: Case study in southern Africa

    Science.gov (United States)

    Jourdan, F.; Bertrand, H.; Féraud, G.; Le Gall, B.; Watkeys, M. K.

    2009-02-01

    Most of the studies on the large igneous provinces (LIPs) focus on Phanerozoic times, and in particular, those related to the disruption of Pangea (e.g. CAMP, Karoo, Parana-Etendeka) while Precambrian LIPs (e.g. Ventersdorpf, Fortescue) remain less studied. Although the investigation of Precambrian LIPs is difficult because they are relatively poorly preserved, assessment of their geochemical characteristics in parallel with younger overlapping LIP is fundamental for monitoring the evolution of the mantle composition through time. Recent 40Ar/ 39Ar dating of the Okavango giant dyke swarm (and related sills) in southern Africa showed that ~ 90% of the dykes were emplaced at 179 ± 1 Ma and belong to the Karoo large igneous province whereas ~ 10% of dykes yielded Proterozoic ages (~ 1-1.1 Ga). Here, we provide new major, trace and rare earth elements analyses of the low-Ti Proterozoic Okavango dyke swarm (PODS) that suggest, combined with age data, a cognate origin with the 1.1 Ga Umkondo large igneous province (UIP), southern Africa. The geochemical characteristics of the PODS and UIP basalts are comparable to those of overlapping low-Ti Karoo basalts, and suggest that both LIPs were derived from similar enriched mantle sources. A mantle plume origin for these LIPs is not easily reconciled with the geochemical dataset and the coincidence of two compositionally similar mantle plumes acting 900 Myr apart is unlikely. Instead, we propose that the Umkondo and Karoo large igneous provinces monitored the slight evolution of a shallow enriched lithospheric mantle from Proterozoic to Jurassic.

  15. The Mozambique Ridge - A LArge IGneous Province with a Complicated Emplacement History

    OpenAIRE

    FISCHER, Maximilian; Uenzelmann-Neben, Gabriele

    2015-01-01

    The Mozambique Ridge (MozR), a supposed part of the South African Large Igneous Province (LIP) in the southwestern Indian Ocean, consists of four major geomorphological units associated with multiple phases of volcanic activity between 140 Ma and 120 Ma. High-resolution seismic reflection data collected in 2014 reveals various magmatic centres within each of the geomorphological units. Intra-basement reflections can be identified up to several hundred ms TWT below top of basement. These ...

  16. The Teles Pires volcanic province: A paleogeoproterozoic silicic-dominated large igneous province in southwest Amazon craton and tectonic implications

    International Nuclear Information System (INIS)

    Large Igneous Provinces (LIPs) are important features of the Earth history especially recognized during Paleo to Mezosoic times when they are related to the break up of supercontinents (Coffin and Eldhom, 1994). These provinces occur in several different tectonic settings such as volcanic passive margins, submarine ridges and continental and oceanic plateaux. Mafic-dominanted provinces are the most well known among the LIPs and the best examples are the Karoo, Kerguelem and Ontong-Java. LIPs including an important silicic component have been described in some basaltic provinces of southern Africa (Milner et al. 1992). More recently, silicic-dominated LIPs have been recognized in eastern Australia (Bryan et al., 2000), in southern South America (Pankhurst et al. 1998) and in Antartica Penninsula (Riley and Leat, 1999). The common characteristics of this kind of LIP include: 1) large volume of silicic rocks with dominance of ignimbrites, 2) active over 40 to 50 m.y.; and 3) spatially and temporally associated with plate break up. In this paper we present the main geologic and geochronologic characteristics of the Teles Pires volcanic province from southwest Amazon Craton, which allow its classification as a Paleoprotorozoic silicic-dominated LIP. Geologic implications of this suggestion includes the existence of a large cratonic plate as old as 1.81Ga for the Amazon Craton, therefore the proposed 1.85-1.55 Ga magmatic arc of Rio Negro-Juruena Province should be reviewed (au)

  17. Correlating Large Igneous Provinces with Lower Mantle Seismic Structure - Where Is the Plume Generation Zone?

    Science.gov (United States)

    Austermann, J.; Kaye, B. T.; Mitrovica, J. X.; Huybers, P. J.

    2014-12-01

    Deep mantle seismic structure is dominated by two large, low shear wave velocity provinces (LLSVPs) below Africa and the Pacific. While different tomography models have come to a consensus over the general geometry of these provinces, the degree of thermal versus chemical heterogeneity that defines them is contentious. The location of plumes that rise from these large structures may provide insight into this question. Large Igneous Provinces (LIPs) are thought to be the surface expression of plumes that formed in the deep mantle and subsequently rose through the mantle and erupted at the surface. When restored to their original location of eruption, these LIPs appear to lie approximately above the margins of LLSVPs. This spatial correlation has been used to argue that plumes are preferentially generated at margins of LLSVPs, a notion that would tend to favor a significant chemical gradient at this margin. We assessed the robustness of this correlation by performing a series of Monte Carlo-based statistical tests (Austermann et al., Geophys. J. Int., 2014). These tests confirm that the reconstructed locations of LIPs are spatially correlated with margins of LLSVPs, but they also show that LIPs are correlated with the full areal extent of LLSVPs (parameterized as regions of slower-than-average shear wave velocity). These two correlations cannot be statistically distinguished, which means the areal extent of LLSVPs is an equally likely zone for plume generation. Therefore, based on current tomography models and reconstructed locations of LIPs, we cannot distinguish whether LIPs originated preferentially at the margins of LLSVPs or whether this correlation is merely an outcome of their origin across the full areal extent of these large scale, deep mantle structures. We will discuss the implications of our findings on the growing debate over the relative contributions of thermal and chemical effects on the net buoyancy of the LLSVPs, a factor that ultimately controls

  18. Evidence of prolonged felsic magmatism within the Karoo large igneous province

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    Kurhila, Matti; Romu, Ilona; Mänttäri, Irmeli; Andersen, Tom; Luttinen, Arto

    2015-04-01

    The Karoo large igneous province (LIP) extends from southern Africa to East Antarctica, and marks the onset of rifting of these two continents. The main stage of volcanic activity occurred ~182180 Ma ago, and was mostly mafic in composition. We report new thermal ionization (TIMS) and secondary ion (SIMS) mass spectrometric U-Pb ages on zircon from felsic lavas in Lebombo monocline, southern Mozambique and from granitoid intrusions in Vestfjella, Dronning Maud Land, Antarctica. Utpostane granite in southern Vestfjella yields a TIMS age of 180.7±1.5 Ma, complying with the main stage of magmatism in the Karoo LIP. Three rhyolitic beds intercalating mafic volcanic layers of the Lebombo monocline give SIMS ages of 182±3 Ma, 178±3 Ma, and 172±2 Ma, respectively. The zircon in the oldest of these can be divided in two groups: (a) internally homogeneous, low U and Pb zircon and (b) oscillatorily zoned, relatively high U and Pb zircon. The ages of these groups are ~179 Ma and ~184 Ma, respectively, but they overlap within error limits, and thus a combined age for this sample is preferred. Finally, an alkali feldspar granite xenolith from a lamproite dike in Vestfjella has a SIMS age of 165±1 Ma. Lu-Hf isotopes were analyzed from zircons in the 172 Ma rhyolite sample. They show fairly homogeneous Hf isotope composition, with initial ɛHf values between +4 and +10. The corresponding crustal residence ages for the zircons vary between ~300 and ~500 Ma, implying source recycling. In light of the new data it is thus evident that, while most of the Karoo LIP may have emplaced within a short time frame, igneous activity continued for at least ~15 Ma.

  19. The Kalkarindji Large Igneous Province and the Early-Middle Cambrian Extinction.

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    Jourdan, Fred; Evins, Lena

    2010-05-01

    Despite being one of the largest large igneous provinces (LIP) on Earth, the recently discovered Kalkarindji LIP, Australia, has received only very little attention (e.g., Glass & Philips, 2005; Evins et al., 2009). This province is located across the Northern Territories and Western Australia and covers a currently known area of ≥ 2.1x106 km² (Evins et al., 2009) with hints that it stretches as far as the southernmost part of South Australia (equivalent to a total area of ≥ 3x106 km²). The province includes flows, intrusions and volcanic tuffs. The age of the province is currently based only on three robust 40Ar/39Ar apparent ages ranging from 504.6 ± 2.5 to 507.5 ± 1.6 Ma (Glass & Philips, 2005; Evins et al., 2009). This province is of particular interest as it seems to coincide with a global anoxic event (Hough et al., 2006) and more importantly, the Early-Middle Cambrian (EMC) extinction where 50% of the genera (e.g. Archeocyaths, Trilobites) went extinct. The age of the EMC extinction has been estimated at ~510 Ma according to the revised timescale of 2009 but so far, attempts to date the extinction level have not yielded any precise date. Considering the now well-established 40K decay constant bias (Min et al., 2000), the 40Ar/39Ar ages obtained so far suggest an emplacement age of the Kalkarindji province between ~509 and ~512 Ma, thus apparently synchronous with the EMC extinction. However, due to the paucity of available ages, it is still not clear if the Kalkarindji LIP was emplaced during only few hundred ka, or rather was more sluggish over few Ma. The Kalkarindji basalts are overlapping thick sulfate-rich evaporite layers and carbonate rocks of the Precambrian central Australia basins. Evaporite and carbonate metamorphism might have been responsible for a significant source of CO2, SO2 and halocarbons as demonstrated for the Siberian traps (Svensen et al., 2009). In addition, the occurrence of pyroclastics eruptions as indicated by the presence

  20. 3D seismic interpretation of subsurface eruptive centers in a Permian large igneous province, Tazhong Uplift, central Tarim Basin, NW China

    Science.gov (United States)

    Yang, Jiangfeng; Zhu, Wenbin; Guan, Da; Zhu, Beibei; Yuan, Liansheng; Xiang, Xuemei; Su, Jinbao; He, Jingwen; Wu, Xinhui

    2015-12-01

    A 1445-km2 high-resolution 3D seismic reflection dataset is used to analyze the Permian large igneous province in the subsurface of the Tazhong area in the central Tarim Basin in northwestern China. Constrained by the synthetic seismograms of four wells, the top and base of the igneous rocks were identified in the seismic data. Seven large volcanic craters, each >10 km2 in area, have been discovered via the application of coherency and amplitude attributes. The thickness and volume of the igneous rocks were obtained by time-depth transformation. In the study area, all of the igneous rocks, with thicknesses from 120 to 1133 m, were formed by eruptions in the Early Permian. These events produced huge erupted volumes (178 km3) and multiple closely spaced volcanic edifices (eruptive center of the Permian igneous rocks in the Tarim Basin.

  1. Reservoir quality of intrabasalt volcaniclastic units onshore Faroe Islands, North Atlantic Igneous Province, northeast Atlantic

    DEFF Research Database (Denmark)

    Ólavsdóttir, Jana; Andersen, Morten Sparre; Boldreel, Lars Ole

    2015-01-01

    The Paleocene and Eocene strata in the western part of the FaroeShetland Basin contain abundant volcanic and volcaniclastic rocks. Recently, hydrocarbon discoveries have been made in reservoirs of siliciclastic origin in intra- and post-volcanic strata in the central Faroe-Shetland Basin that sho...

  2. Magmatic underplating beneath the Emeishan large igneous province (South China) revealed by the COMGRA-ELIP experiment

    Science.gov (United States)

    Deng, Yangfan; Chen, Yun; Wang, Peng; Essa, Khalid S.; Xu, Tao; Liang, Xiaofeng; Badal, José

    2016-03-01

    Because of the abundant geological, geochemical and geophysical studies conducted on the Emeishan large igneous province (ELIP) in South China, the Permian mantle plume model associated with this region is widely accepted. Furthermore, the dome-shaped structure related with this plume has been determined with success by sedimentological data and gravity stripping. Although the sediment thickness, upper crust, Moho depth and the lithosphere-asthenosphere boundary (LAB) are well constrained by active- and passive-source seismological results, the density anomaly in ELIP is still a poorly constrained issue that needs further attention. With the aim especially to understand the impact on surface of the magmatic processes that originated in the deep mantle, we performed the COMGRA-ELIP gravity experiment across this region. Using a stripping method, we determined the residual gravity in ELIP and surrounding areas. The residual gravity reaches a maximum value of + 150 mGal in the inner zone of ELIP and its strength decreases gradually when measuring from the inner zone to the middle and outer zones. Combining active and passive seismic results and the least-squares variance analysis method, we propose a strong density contrast of 0.2 g/cm3 (density of 3.14 g/cm3) for the 15- to 20-km-thick igneous layer accreted at the base of the crust, as evidence of crustal underplating in ELIP, to explain the present-day residual gravity anomaly.

  3. Magmatic underplating and crustal growth in the Emeishan Large Igneous Province, SW China, revealed by a passive seismic experiment

    Science.gov (United States)

    Chen, Yun; Xu, Yigang; Xu, Tao; Si, Shaokun; Liang, Xiaofeng; Tian, Xiaobo; Deng, Yangfan; Chen, Lin; Wang, Peng; Xu, Yihe; Lan, Haiqiang; Xiao, Fuhui; Li, Wei; Zhang, Xi; Yuan, Xiaohui; Badal, José; Teng, Jiwen

    2015-12-01

    In an attempt to characterize the subsurface structure that is related to fossil mantle plume activity, a comprehensive geophysical investigation was conducted in the Emeishan Large Igneous Province (ELIP). The nature and geometry of the crust were examined within the scheme of the domal structure of ELIP, which comprises the Inner, Intermediate and Outer zones, which are defined on the basis of the biostratigraphy of pre-volcanic sediments. The bulk crustal properties within the Inner Zone are characterized by high density, high P-wave velocity, high Vp/Vs ratios and large crustal thickness. A visible continuous seismic converter is present in the upper part of the crust in the whole Intermediate Zone and the eastern part of the Inner Zone, but it is absent in the Inner Zone, where another seismic converter is observed in the lower part of the crust. The geometric configuration of these converters is attributable to the addition of mantle-derived melts to the pre-existing crust and subsequent interaction between them. The crustal geometry, which is delineated by the migrated image of receiver functions from the passive seismic experiment, and the crustal properties collectively suggest that a mafic layer of 15-20 km thickness and 150-180 km width exists at the base of the crust in the Inner Zone. Such a mafic layer reflects a vertical crustal growth through magmatic underplating at the base of the crust and intraplating within the upper crust. The salient spatial correlation between the deep crustal structure and the dome strongly supports a genetic link between crustal thickening and plume activity, if the pre-volcanic domal uplift is generated by the Permian Emeishan mantle plume. This arrangement is further supported by the consistency of the extent of crustal uplift estimated by isostatic equilibrium modeling and sedimentary data. This study therefore characterizes and provides evidence for a plume-modified crust in a large igneous province.

  4. A failure to reject: Testing the correlation between large igneous provinces and deep mantle structures with EDF statistics

    Science.gov (United States)

    Doubrovine, Pavel V.; Steinberger, Bernhard; Torsvik, Trond H.

    2016-03-01

    Absolute reconstructions of large igneous provinces (LIPs) for the past 300 Ma reveal a remarkable spatial pattern suggesting that almost all LIPs have erupted over the margins of the two large-scale structures in the Earth's lower mantle commonly referred to as the Large Low Shear-wave Velocity Provinces (LLSVPs). This correlation suggests that mantle plumes that have triggered LIP eruptions rose from the margins of LLSVPs, implying long-term stability of these structures and suggesting that they may be chemically distinct from the bulk of the mantle. Yet, some researchers consider the LLSVPs to be purely thermal upwellings, arguing that the observed distribution of LIPs can be explained by plumes randomly forming over the entire areas of LLSVPs. Here we examine the correlation between the LIPs and LLSVPs using nonparametric statistical tests, updated plate reconstructions, and a large number of alternative definitions of LLSVPs based on seismic tomography. We show that probability models assuming plume sources originating at the margins of LLSVPs adequately explain the observed distribution of reconstructed LIPs. In contrast, we find strong evidence against the models seeking to link LIPs with plumes randomly forming over the entire LLSVP areas. However, the hypothesis proposing that the correlation can be explained by plumes randomly forming over a larger area of slower-than-average shear wave velocities in the lowermost mantle cannot be ruled out formally. Our analysis suggests that there is no statistically sound reason for questioning the hypothesis that the LIPs correlate with the margins of LLSVP globally.

  5. Low-Ti melts from the southeastern Siberian Traps Large Igneous Province: Evidence for a water-rich mantle source?

    Indian Academy of Sciences (India)

    Alexei V Ivanov; Elena I Demonterova; Sergei V Rasskazov; Tatyana A Yasnygina

    2008-02-01

    Siberian Traps Large Igneous Province (STLIP) is one of the most voluminous volcanic provinces on Earth. The dominant erupted rocks are low-Ti basalts, which make up 80% by volume of the classical Noril’sk lava sequence. In the west Siberian basin and Maymecha-Kotuy area, the low- Ti basalts make up about 99% and 50% by volume, respectively. Dolerite sills in the Angara– Taseevskaya Syncline at the southeastern STLIP exhibit trace element patterns and Sr isotope ratios typical of the low-Ti basalts of the Noril’sk sequence. The most Mg-rich (MgO 9.5–11 wt%) and hence least differentiated dolerites are characterized by trace element patterns with Ta-Nb depletion, low Ce/Pb and high Sr/Pr. These trace element features are similar to water-saturated, mantle wedge-derived island arc basalts. These imply an important role of subduction fluid-derived trace elements in the source of melting beneath the Angara–Taseevskaya Syncline and other regions of the STLIP. Less magnesium rocks (MgO 3.8–6.1 wt%) with less prominent Ta-Nb depletion, higher Ce/Pb and lower Sr/Pr could be produced via olivine-plagioclase fractionation of primary high-magnesium melts.

  6. High-precision geochronology links the Ferrar large igneous province with early-Jurassic ocean anoxia and biotic crisis

    Science.gov (United States)

    Burgess, S. D.; Bowring, S. A.; Fleming, T. H.; Elliot, D. H.

    2015-04-01

    Apparent synchrony between eruption/emplacement of large igneous province (LIP) magmas and mass extinction has led to the implication of magmatism as a primary trigger of global scale environmental change. Evaluating the efficacy of magmatism as a driver of global change depends on the relative timing of magmatism and environmental change, and the magma effusion/intrusion rate, both of which can be constrained by high-precision geochronology. Early Jurassic (Pliensbachian-Toarcian) global ocean anoxia and acidification, carbon isotope perturbations, and biotic crisis have been linked to "synchronous" eruption and emplacement of the Karoo and Ferrar LIPs. To better constrain the timing and duration of Ferrar magmatism, we apply the single crystal, chemical abrasion U-Pb ID-TIMS method to zircon crystals isolated from twenty Ferrar LIP sills and lavas, and the Dufek intrusion. Dates suggest that both intrusive and extrusive Ferrar magmatism occurred over an interval of 349 ± 49 kyr, beginning with intrusive magmatism as early as 182.779 ± 0.033 Ma. Lava eruption was synchronous with, and in some cases postdates intrusion. When coupled with existing geochronology on the Karoo province, our dates confirm broad synchrony between Karoo and Ferrar magmatism, though Karoo magmatism began demonstrably prior to Ferrar magmatism, starting as early as 183.246 ± 0.045 Ma. The short-lived magmatic history of the Ferrar LIP makes it a plausible trigger for early-Jurassic environmental change.

  7. Prolonged plume volcanism in the Caribbean Large Igneous Province: New insights from Curaçao and Haiti

    Science.gov (United States)

    Loewen, Matthew W.; Duncan, Robert A.; Kent, Adam J. R.; Krawl, Kyle

    2013-10-01

    We present 36 new 40Ar-39Ar incremental heating age determinations from the Caribbean Large Igneous Province (CLIP) providing evidence for extended periods of volcanic activity and suggest a new tectonomagmatic model for the province's timing and construction. These new 40Ar-39Ar ages for the Curaçao Lava Formation (CLF) and Haiti's Dumisseau Formation show evidence for active CLIP volcanism from 94 to 63 Ma. No clear changes in geochemical character are evident over this period. The CLF has trace element signatures (e.g., Zr/Nb = 10-20) and flat rare earth element (REE) trends consistent with plume volcanism. The Dumisseau Formation also has plume-like geochemistry and steeper REE trends similar to ocean island basalts. Volcanism in the Dumisseau Formation appears to have largely ceased by 83 Ma while at Curaçao it continued until 63 Ma. A rapidly surfacing and melting plume head alone does not fit this age distribution. Instead, we propose that the residual Galapagos plume head, following initial ocean plateau construction, was advected eastward by asthenospheric flow induced by subducting oceanic lithosphere. Slab rollback at the Lesser Antilles and Central America subduction zones created an extensional regime within the Caribbean plate. Mixing of plume with upwelling asthenospheric mantle provided a source for intermittent melting and eruption through the original plateau over a ˜30 Ma period.

  8. Intense and widespread seismicity during the end-Triassic mass extinction due to emplacement of a large igneous province

    DEFF Research Database (Denmark)

    Lindström, Sofie; Pedersen, Gunver Krarup; van de Schootbrugge, Bas;

    2015-01-01

    Multiple levels of earthquake-induced soft-sediment deformations (seismites) are concentrated in the end-Triassic mass extinction interval across Europe. The repetitive nature of the seismites rules out an origin by an extraterrestrial impact. Instead, this intense seismic activity is linked to the...... formation of the Central Atlantic magmatic province (CAMP). By the earliest Jurassic the seismic activity had ceased, while extrusive volcanism still continued and biotic recovery was on its way. This suggests that magmatic intrusions into sedimentary strata during early stages of CAMP formation caused...

  9. Geological evolution of the Coombs Allan Hills area, Ferrar large igneous province, Antarctica: Debris avalanches, mafic pyroclastic density currents, phreatocauldrons

    Science.gov (United States)

    Ross, Pierre-Simon; White, James D. L.; McClintock, Murray

    2008-05-01

    The Jurassic Ferrar large igneous province of Antarctica comprises igneous intrusions, flood lavas, and mafic volcaniclastic deposits (now lithified). The latter rocks are particularly diverse and well-exposed in the Coombs-Allan Hills area of South Victoria Land, where they are assigned to the Mawson Formation. In this paper we use these rocks in conjunction with the pre-Ferrar sedimentary rocks (Beacon Supergroup) and the lavas themselves (Kirkpatrick Basalt) to reconstruct the geomorphological and geological evolution of the landscape. In the Early Jurassic, the surface of the region was an alluvial plain, with perhaps 1 km of mostly continental siliciclastic sediments underlying it. After the fall of silicic ash from an unknown but probably distal source, mafic magmatism of the Ferrar province began. The oldest record of this event at Allan Hills is a ≤ 180 m-thick debris-avalanche deposit (member m1 of the Mawson Formation) which contains globular domains of mafic igneous rock. These domains are inferred to represent dismembered Ferrar intrusions emplaced in the source area of the debris avalanche; shallow emplacement of Ferrar magmas caused a slope failure that mobilized the uppermost Beacon Supergroup, and the silicic ash deposits, into a pre-existing valley or basin. The period which followed ('Mawson time') was the main stage for explosive eruptions in the Ferrar province, and several cubic kilometres of both new magma and sedimentary rock were fragmented over many years. Phreatomagmatic explosions were the dominant fragmentation mechanism, with magma-water interaction taking place in both sedimentary aquifers and existing vents filled by volcaniclastic debris. At Coombs Hills, a vent complex or 'phreatocauldron' was formed by coalescence of diatreme-like structures; at Allan Hills, member m2 of the Mawson Formation consists mostly of thick, coarse-grained, poorly sorted layers inferred to represent the lithified deposits of pyroclastic density currents

  10. Magmatism and Eurekan deformation in the High Arctic Large Igneous Province

    DEFF Research Database (Denmark)

    Tegner, Christian; Storey, Michael; Holm, Paul Martin;

    2011-01-01

    perthite feldspars and coeval resetting of Rb–Sr isotopes by hydrothermal fluids provide further support for thermal overprinting. This thermal event is interpreted as a result of compressional tectonism of the Kap Cannon Thrust Zone in which older Palaeozoic metasediments were thrusted northwards over the...... spreading in the Northeast Atlantic resulted in spreading and volcanism (61– 25 Ma) on both sides of Greenland, pushing Greenland northwards relative to North America. The tectonic setting in the High Arctic thus changed from extensional to compressional and volcanic activity was terminated. Evaluation of...... plate kinematic models shows that the relative northwards govement of Greenland culminated in the Eocene, coinciding with thermal resetting. We conclude that compression in North Greenland peaked at 49–47 Ma and coincided with the Eurekan Orogeny in a belt across the Canadian Arctic Islands and western...

  11. Anatomy of a deep crustal volcanic conduit system; The Reinfjord Ultramafic Complex, Seiland Igneous Province, Northern Norway

    Science.gov (United States)

    Grant, Thomas B.; Larsen, Rune B.; Anker-Rasch, Lars; Grannes, Kim Rune; Iljina, Markku; McEnroe, Suzanne; Nikolaisen, Even; Schanche, Mona; Øen, Endre

    2016-05-01

    The Reinfjord Ultramafic Complex, Seiland Igneous Province represents a lower crustal magma chamber (25-30 km depth) that likely records a deep conduit system for mantle derived melts ascending through the continental crust. It consists of cumulates of dunite, wehrlite, olivine clinopyroxene as well as subordinate lherzolite and websterites, intruded into gabbro-norite and metasediment gneisses. Field, petrographic and geochemical data show that the intrusion developed through fractional crystallization and interactions between new batches of magma and partially solidified cumulates. This resulted in a 'reverse fractionation sequence' whereby cumulates became progressively more MgO and olivine rich with time. Contamination by partial melting of the gabbro-norite is evident in the marginal zones, but is limited in the central parts of the intrusion. Interrupted crystallization sequences of olivine → olivine + clinopyroxene and the absence of significant amounts of more evolved melts, suggests that large volumes of melt passed through the system to shallower levels in the crust leaving behind the cumulate sequences observed at Reinfjord. Therefore, the Reinfjord Ultramafic Complex represents a deep crustal conduit system, through which mantle derived melts passed. The parent melts are likely to have formed from partial melting of mantle with residual garnet and clinopyroxene.

  12. Advancing Late Mesoproterozoic Paleogeography With New Constraints From The Keweenawan Rift And The Umkondo Large Igneous Province

    Science.gov (United States)

    Swanson-Hysell, N.; Kilian, T. M.; Bowring, S. A.; Hanson, R. E.; Burgess, S. D.; Ramezani, J.

    2014-12-01

    Laurentia and Kalahari are currently interpreted as independently moving continents ca. 1110 million years ago that subsequently became conjoined in the supercontinent Rodinia. Their relative positions and orientations are dependent both on the directional comparison of paleomagnetic poles and geomagnetic polarity choices for those poles. In this contribution, we use newly developed and existing paleomagnetic and geochronological data from both the ca. 1110-1085 Ma Midcontinent Rift of Laurentia and the ca. 1109 Ma Umkondo Large Igneous Province (LIP) of Kalahari to present improved constraints on relations between the two continents. Previous mean poles for the Umkondo LIP have been either calculated by taking the mean of regional submeans or at the site level which is problematic given the preponderance of multiple sites from single individual cooling units. We report a new Umkondo grand mean pole that is the mean of the virtual geomagnetic poles (VGPs) of individual cooling units and is reinforced with new data from ~20 previously unstudied Umkondo sills from Botswana. This approach yields a pole whose position and uncertainty are the most robust calculated to date. The portion of Laurentia's Mesoproterozoic apparent polar wander path (APWP) known as the Logan Loop and Keweenawan Track partially overlaps in age with the Umkondo pole and is of central importance in efforts to reconstruct late Mesoproterozoic paleogeography. Ongoing debates as to the geometry and timing of Rodinia assembly critically hinge on the comparison of paleomagnetic poles from other continents to the Keweenawan record. We present an updated compilation for the Keweenawan Track APWP using an improved chronostratigraphic context enabled by new geochronological and paleomagnetic data. Ongoing improvements and time-calibration of this record further constrains the rate of Laurentia's motion and provides opportunities for increased rigor in the determination of relative paleogeographic

  13. Geochemistry of Central Atlantic Magmatic Province (CAMP) sills from deep boreholes in the Amazonas and Solimões basins, Brazil

    Science.gov (United States)

    Hatlen Heimdal, Thea; Svensen, Henrik H.; Pereira, Egberto; Planke, Sverre

    2016-04-01

    The Central Atlantic Magmatic Province (CAMP) is one of the most extensive Large Igneous Provinces (LIPs), and is associated with the breakup of Pangea and the subsequent opening of the central Atlantic Ocean. A large part of the province, including > 1 M km2 basins containing sill intrusions, is located in Brazil but has received limited attention due to the lack of outcrops. We have studied CAMP sills from seven deep boreholes (up to 3100 m deep) in the Amazonas and Solimões basins, northern Brazil. The boreholes contain up to ~ 482 m of sills (18 % of the stratigraphy), with a maximum individual sill thickness of 140 m. The sills were partly emplaced into thick Carboniferous evaporites. The main mineral phases of the sills include plagioclase and pyroxene, with accessory apatite, biotite, ilmenite and quartz. The majority of the sills are low-Ti dolerites (TiO2 rocks range from basalt to basaltic andesite and plot in the tholeiitic field defined within the total alkali versus silica (TAS) classification. C1 chondrite normalized Rare Earth Element (REE) patterns for both Ti-groups show increasing LREE compared to HREE (La/Lu = 2.2 - 4.1) with no major anomalies, and attest to a relatively evolved nature (La = 17-65 ppm). Primitive mantle normalized patterns for low-Ti rocks show negative anomalies for Nb, Ta, P and Ti and positive for K, whereas the high-Ti rocks show generally opposite anomalies. Late stage patches in the dolerites contain apatite, quartz and Cl-bearing biotite, suggesting the presence of halogens that may partly derive from the host sedimentary rocks.

  14. Timing and duration of volcanism in the North Atlantic Igneous Province

    DEFF Research Database (Denmark)

    Storey, Michael; Duncan, Robert A.; Tegner, Christian

    2007-01-01

    Greenland-Iceland ridge, that subsequently connected in an age-progressive trend to present hotspot activity in southeastern Iceland. The startup mantle plume head and tail model, with moderate excess temperature (ΔT ~ 100 °C) and active upwelling, best explains the time, space and compositional aspects of...

  15. Origin of Siletzia, a Large Igneous Province in the Cascadia Forearc, and the Early History of the Yellowstone Hotspot

    Science.gov (United States)

    Wells, R. E.; Bukry, D.; Friedman, R. M.; Pyle, D. G.; Duncan, R. A.; Haeussler, P. J.

    2015-12-01

    Siletzia is a Paleogene large igneous province (LIP) forming the oceanic basement of coastal OR, WA and S. BC that was accreted to North America (NAM) in the early Eocene. Crustal thickness from seismic refraction ranges from 10 to 32 km, with 16 km of pillow and subaerial basalt exposed on the Olympic Peninsula. At 1.7-2.4 x 106 km3, Siletzia is at least 10 times the volume of the Columbia River flood basalts. U-Pb and 40Ar/39Ar ages, global coccolith (CP) zones, and magnetostratigraphy allow correlation of Siletzia with the 2012 geomagnetic polarity time scale. Siletzia was erupted 56-49 Ma (Chron 25-22), and accretion was completed between 51 and 49 Ma in Oregon. Siletzia's composition, great crustal thickness, rapid eruption, and timing of accretion are consistent with formation as an oceanic plateau. Eight m.y. after accretion, margin-parallel extension and regional dike swarms accompanied the voluminous tholeiitic to highly alkalic Tillamook magmatic episode in the forearc (41.6 Ma; CP14a; Chron 19r). We examined the origin of Siletzia and the possible role of a long-lived Yellowstone hotspot (YHS) in GPlates. In most reference frames, the YHS is ~ 500km offshore S. OR, near an inferred northeast-striking Kula- Farallon and/or Resurrection-Farallon ridge 60 to 50 Ma. The YHS could have provided the 56-49 Ma source on the Farallon plate for Siletzia, which in the model accretes to NAM by 50 Ma. A sister plateau, the Eocene basalt basement of the Yakutat terrane, now in Alaska, may have formed on the adjacent Kula (or Resurrection) plate and accreted to British Columbia at about the same time. Following accretion, the leading edge of NAM overrode the YHS ca. 42 Ma. The encounter with an active YHS may explain the voluminous 42-34 Ma Tillamook episode and forearc extension. Clockwise rotation of western Oregon about a pole in the backarc has since moved the Tillamook center and underlying Siletzia northward ~250 km from the likely hotspot track on NAM.

  16. Origin of Siletzia, an Accreted Large Igneous Province in the Cascadia Forearc, and the Early History of the Yellowstone Hotspot

    Science.gov (United States)

    Wells, R. E.; Bukry, D.; Friedman, R. M.; Pyle, D. G.; Duncan, R. A.; Haeussler, P. J.; Wooden, J.

    2014-12-01

    Siletzia as named by Irving (1979) is a Paleogene large igneous province forming the oceanic basalt basement of coastal OR, WA and S. BC that was accreted to North America in the early Eocene. U-Pb (magmatic, detrital zircon) and 40Ar/39Ar ages constrained by mapping, global coccolith (CP) zones, and magnetic polarities permit correlation of basalts with the geomagnetic polarity time scale of Gradstein et al. (2012). Siletzia was rapidly erupted 56-49 Ma (Chron 25-22), and accretion was completed between 51 and 49 Ma in Oregon. Magmatism continued until ca. 46 Ma with emplacement of a basalt sill complex during or shortly after accretion. Siletzia's great crustal thickness, rapid eruption, and timing of accretion are consistent with formation as an oceanic plateau. Eight m.y. after accretion, margin-parallel extension and regional dike swarms mark the Tillamook magmatic episode in the forearc (41.6 Ma; CP zone 14a; Chron 19r). We examined the origin of Siletzia and the possible role of a long-lived Yellowstone hotspot (YHS) in an open source plate modeling program. In most reference frames, the YHS is on or near an inferred northeast-striking Kula- Farallon and/or Resurrection-Farallon ridge 60 to 50 Ma. The YHS thus could have provided a 56-49 Ma source on the Farallon plate for Siletzia, which accreted to North America by 50 Ma. A sister plateau, the Eocene basalt basement of the Yakutat terrane, now in Alaska, formed on the adjacent Kula (or Resurrection) plate and accreted to coastal British Columbia at about the same time. Following accretion of Siletzia, the leading edge of North America overrode the YHS ca. 42 Ma. The encounter with an active YHS may explain the voluminous high-Ti tholeiitic to alkalic magmatism of the 42-34 Ma Tillamook episode and extension in the forearc. Clockwise rotation of western Oregon about a pole in the backarc has since moved the Tillamook center and underlying Siletzia northward ~250 km from the probable hotspot track on North

  17. Molecular biogeochemical provinces in the Atlantic Surface Ocean

    Science.gov (United States)

    Koch, B. P.; Flerus, R.; Schmitt-Kopplin, P.; Lechtenfeld, O. J.; Bracher, A.; Cooper, W.; Frka, S.; Gašparović, B.; Gonsior, M.; Hertkorn, N.; Jaffe, R.; Jenkins, A.; Kuss, J.; Lara, R. J.; Lucio, M.; McCallister, S. L.; Neogi, S. B.; Pohl, C.; Roettgers, R.; Rohardt, G.; Schmitt, B. B.; Stuart, A.; Theis, A.; Ying, W.; Witt, M.; Xie, Z.; Yamashita, Y.; Zhang, L.; Zhu, Z. Y.; Kattner, G.

    2010-12-01

    One of the most important aspects to understand marine organic carbon fluxes is to resolve the molecular mechanisms which convert fresh, labile biomolecules into semi-labile and refractory dissolved and particulate organic compounds in the ocean. In this interdisciplinary project, which was performed on a cruise with RV Polarstern, we carried out a detailed molecular characterisation of dissolved organic matter (DOM) on a North-South transect in the Atlantic surface ocean in order to relate the data to different biological, climatic, oceanographic, and meteorological regimes as well as to terrestrial input from riverine and atmospheric sources. Our goal was to achieve a high resolution data set for the biogeochemical characterisation of the sources and reactivity of DOM. We applied ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS), nutrient, trace element, amino acid, and lipid analyses and other biogeochemical measurements for 220 samples from the upper water column (0-200m) and eight deep profiles. Various spectroscopic techniques were applied continuously in a constant sample water flow supplied by a fish system and the moon pool. Radiocarbon dating enabled assessing DOC residence time. Bacterial abundance and production provided a metabolic context for the DOM characterization work and pCO2 concentrations. Combining molecular organic techniques and inductively coupled plasma mass spectrometry (ICP-MS) established an important link between organic and inorganic biogeochemical studies. Multivariate statistics, primarily based on FT-ICR-MS data for 220 samples, allowed identifying geographical clusters which matched ecological provinces proposed previously by Longhurst (2007). Our study demonstrated that marine DOM carries molecular information reflecting the “history” of ocean water masses. This information can be used to define molecular biogeochemical provinces and to improve our understanding of element fluxes in

  18. Mineral reactions and strain localization in a sheared mafic granulite infiltrated by melt (Seiland Igneous Province, Norway)

    Science.gov (United States)

    degli Alessandrini, Giulia; Menegon, Luca; Malaspina, Nadia; Dijkstra, Arjan; Anderson, Mark

    2016-04-01

    This study investigates the deformation mechanisms of a metagabbroic dyke experiencing syn-kinematic melt-rock interaction in a continental lower-crustal shear zone in the Seiland Igneous Province (northern Norway). Solid state shearing occurred at T ≈750-820 °C, P ≈0.75-0.95 GPa and was coeval with melt infiltration from dehydration melting of adjacent metasediments, as evident from thin leucosome veinlets within the dykes. The mylonite consists of cpx [Ca0.47,Mg0.35,Fe0.18]SiO3 + opx [Ca0.1,Mg0.5,Fe0.4]SiO3 + pl (An77Ab22Or1) porphyroclasts with localized grt and ilm coronas, embedded in a fine grained matrix of cpx + opx + pl + qtz + ilm ± kfs. Porphyroclasts range in size (diameter) between 25 to 650 μm, whereas the fine grain matrix is consistently below 10 μm (average 4-7 μm). Porphyroclasts show varying degrees of elongation, with the opx reaching aspect ratios of 1:16 and the cpx reaching rare maxima of 1:7. Cpx and pl porphyroclasts are micro-fractured and micro-boudinaged with fine-grained material infill. Texturally, opx porphyroclasts display a marked crystallographic preferred orientation (CPO) and activity of the {100} and minor {100} slip systems, whereas cpx and pl porphyroclasts are randomly oriented. All porphyroclasts have strong internal misorientations (undulatory and sweeping extinction) and lack recovery features (subgrains). The fine-grained polyphase matrix wrapping the porphyroclasts displays weak to absent CPO, with the exception of opx that shows a {100} poles-to-planes maxima perpendicular to the foliation. Based on the microstructure, we argue that a large part of the matrix is the product of metamorphic reactions in the presence of melt. To test this hypothesis, the interaction between the studied mafic dyke and an adjacent felsic leucosome was modelled using PerpleX for P-T conditions ranging between 7-9 kbar and 700-1000°C. Results show that the syn-kinematic mineral assemblage (opx + cpx + pl + qtz + ilm ± kfs) can be

  19. Zircon and baddeleyite U-Pb geochronology and Hf isotopes from the Central Atlantic Magmatic Province (CAMP)

    Science.gov (United States)

    Davies, Joshua; Marzoli, Andrea; Bertrand, Herve; Youbi, Nasrrddine; Schaltegger, Urs

    2016-04-01

    Large Igneous Provinces (LIPs) are anomalously large volumes of dominantly mafic magma that erupted and intruded into the upper crust over short time scales. The origin of these volcanic provinces is very likely specific for each case, partly explained by plate tectonic processes or mantle plumes. Despite an ambivalent plate tectonic connection, there is a striking temporal correlation between the timing of LIPs and periods of mass extinction on Earth. However, establishing the relationship between these two is quite complicated since mass extinctions are typically recognised in the marine record, and LIPs are usually terrestrially emplaced. High precision geochronology of LIPs is essential to (i) establish the synchrony and infer the causal relationship with mass extinctions, and (ii) to understand how LIPs form. In this study, we apply high-precision zircon and baddeleyite U-Pb geochronology to rocks from the ~200 Ma Central Atlantic Magmatic Province (CAMP), in an attempt to reconstruct the overall timing of the event, its spatial distribution in time, and determine its relationship with the end-Triassic mass extinction. We also present Hf isotope data from the separated zircon and baddeleyite to both elucidate the origin of the LIP and also to determine if the magmas all originate from the same source. Our data suggest that the majority of the CAMP magmas were emplaced over a 0.5 Ma period from ~201.5 Ma to ~201.0 Ma with a possible small secondary event occurring much later at ~199 Ma. Spatially, it appears that CAMP magmatism occurred roughly simultaneously over the entire province (i.e. ~8000 Km North to South). However, the Hf isotopic composition varies over this length with the highest values (~5.5 ɛHf) occurring in a small area to the south of the province in Brazil and Sierra Leone. Towards the north, the ɛHf values become negative, indicating the presence of an older or more enriched component in the magmas. Our geochronology also indicates that CAMP

  20. A new grand mean palaeomagnetic pole for the 1.11 Ga Umkondo large igneous province with implications for palaeogeography and the geomagnetic field

    Science.gov (United States)

    Swanson-Hysell, N. L.; Kilian, T. M.; Hanson, R. E.

    2015-12-01

    We present a new grand mean palaeomagnetic pole (Plong: 222.1°, Plat: -64.0°, A95: 2.6°, N = 49) for the ca. 1110 Ma Umkondo large igneous province (LIP) of the Kalahari Craton. New palaeomagnetic data from 24 sills in Botswana and compiled reprocessed existing data are used to develop a palaeomagnetic pole as the Fisher mean of cooling unit virtual geomagnetic poles (VGPs). The mean and its associated uncertainty provide the best-constrained pole yet developed for the province. Comparing data from individual cooling units allows for evaluation of palaeosecular variation at this time in the Mesoproterozoic. The elongation of the population of VGPs is consistent with that predicted by the TK03.GAD model lending support to the dipolar nature of the field in the late Mesoproterozoic. In our new compilation, 4 of 59 (˜7 per cent) of the igneous units have northerly declinations while the rest are south-directed indicating that a geomagnetic reversal occurred during magmatic activity. Interpreting which of these polarities corresponds with a normal or reversed geomagnetic field relative to other continents can constrain the relative orientations between cratons with time-equivalent data. This interpretation is particularly important in comparison to Laurentia as it bears on Kalahari's involvement and position in the supercontinent Rodinia. The dominance of south-directed declinations within the Umkondo Province was previously used to suggest that these directions are the same polarity as reversed directions from the early magmatic stage of the Keweenawan Midcontinent Rift of Laurentia. Two Umkondo sills with northerly declinations have U-Pb baddeleyite ages of ca. 1109 Ma that are temporally close to dated Midcontinent Rift units having reversed directions. Based on this comparison, and palaeomagnetic data from younger units in the Kalahari Craton, we favour the option in which the sites with northerly declinations from the Umkondo Province correspond to the

  1. Long duration (>4 Ma) and steady-state volcanic activity in the early Cretaceous Paraná-Etendeka Large Igneous Province: New palaeomagnetic data from Namibia

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    Dodd, Sarah C.; Mac Niocaill, Conall; Muxworthy, Adrian R.

    2015-03-01

    There is long-standing correlation between Large Igneous Provinces (LIPs) and major mass extinction events in the Geological Record, postulated to be due to the emission of large quantities of volcanic gases over a geologically short period of time causing major climatic perturbations within the Earth system. The ∼135 Ma Paraná-Etendeka volcanic province of Brazil and Namibia represents something of an enigma amongst LIPs. Despite an erupted volume (>1 Mkm3) comparable to other LIPs associated with mass extinctions, such as the Siberian or Deccan traps, it is not linked to a known mass extinction event. This suggests that the Paraná-Etendeka volcanic province was emplaced over longer timescales than other LIPs, and/or emitted a lower concentration of volatiles, directly or indirectly during its emplacement. We present a new, detailed magnetostratigraphy for the Etendeka portion of the province that suggests emplacement took place over longer timescales (>4 Ma) than those associated with other LIPs. Palaeomagnetic analysis of 893 specimens from 99 sites, in sections that encompass nearly the complete Etendeka stratigraphy, yielded high-quality data from 70 sites (612 specimens). These record 16 individual polarity intervals, which can be correlated with Chrons 15 to 11 of the geomagnetic polarity time scale (GPTS) while also providing two new, high quality palaeopoles for South Africa at 130-135 Ma. Our magnetostratigraphy reveals a minimum period of volcanic activity in excess of 4 Myrs and, importantly, we find no evidence for major changes in the rates of volcanic activity through that time period, in contrast to other LIPs where volcanism seems to be concentrated in major pulses. This suggests that the anomalously feeble environmental impact of Paraná-Etendeka volcanism may be due to lower effusion rates reducing the atmospheric loading due to volcanogenic volatiles.

  2. Flow dynamics in mid-Jurassic dikes and sills of the Ferrar large igneous province and implications for long-distance magma transport

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    Airoldi, Giulia M.; Muirhead, James D.; Long, Sylvan M.; Zanella, Elena; White, James D. L.

    2016-06-01

    Magma flow paths in sill-fed dikes of the Ferrar large igneous province (LIP), contrast with those predicted by classic models of dike transport in LIPs and magmatic rift settings. We examine anisotropy of magnetic susceptibility (AMS) flow paths in dike networks at Terra Cotta Mountain and Mt. Gran, which intruded at paleodepths of ~ 2.5 and ~ 1.5 km. These intrusions (up to 30 m thick) exhibit irregular, interconnected dike-sill geometries and adjoin larger sills (~ 200-300 m thick) at different stratigraphic levels. Both shallowly dipping and sub-vertical magma flow components are interpreted from AMS measurements across individual intrusions, and often match macroscopic flow indicators and variations in dike attitudes. Flow paths suggest that intrusive patterns and magma flow directions depended on varying stress concentrations and rotations during dike and sill propagation, whereas a regional extensional tectonic control was negligible or absent. Unlike giant dike swarms in LIPs elsewhere (e.g., 1270 Ma MacKenzie LIP), dikes of the Ferrar LIP show no regionally consistent vertical or lateral flow patterns, suggesting these intrusion were not responsible for long-distance transport in the province. In the absence of regionally significant, colinear dike swarms, or observed intrusions at crustal depths ≥ 4 km, we suggest that long distance magma transport occurred in sills within Beacon Supergroup sedimentary rocks. This interpretation is consistent with existing geochemical data and thermal constraints, which support lateral magma flow for ~ 3,500 km across the Gondwana supercontinent before freezing.

  3. Globally enhanced mercury deposition during the end-Pliensbachian extinction and Toarcian OAE: A link to the Karoo-Ferrar Large Igneous Province

    Science.gov (United States)

    Percival, L. M. E.; Witt, M. L. I.; Mather, T. A.; Hermoso, M.; Jenkyns, H. C.; Hesselbo, S. P.; Al-Suwaidi, A. H.; Storm, M. S.; Xu, W.; Ruhl, M.

    2015-10-01

    The Mesozoic Era featured emplacement of a number of Large Igneous Provinces (LIPs), formed by the outpouring of millions of cubic kilometres of basaltic magma. The radiometric ages of several Mesozoic LIPs coincide with the dates of Oceanic Anoxic Events (OAEs). As a result of these coincidences, a causal link has been suggested, but never conclusively proven. This study explores the use of mercury as a possible direct link between the Karoo-Ferrar LIP and the coeval Toarcian OAE (T-OAE). Mercury is emitted to the atmosphere as a trace constituent of volcanic gas, and may be distributed globally before being deposited in sediments. Modern marine deposits show a strong linear correlation between mercury and organic-matter content. Results presented here indicate departures from such a simple linear relationship in sediments deposited during the T-OAE, and also during the Pliensbachian-Toarcian transition (an event that saw elevated benthic extinctions and carbon-cycle perturbations prior to the T-OAE). A number of depositional settings illustrate an increased mercury concentration in sediments that record one or both events, suggesting a rise in the depositional flux of this element. Complications to this relationship may arise from very organic-rich sediments potentially overprinting any Hg/TOC signal, whereas environments preserving negligible organic matter may leave no record of mercury deposition. However, the global distribution of coevally elevated Hg-rich levels suggests enhanced atmospheric mercury availability during the Early Toarcian, potentially aided by the apparent affinity of Hg for terrestrial organic matter, although the relative importance of aquatic vs terrestrial fixation of Hg in governing these enrichments remains uncertain. A perturbation in atmospheric Hg is most easily explained by enhanced volcanic output. It is suggested that extrusive igneous activity caused increased mercury flux to the Early Toarcian sedimentary realm, supporting the

  4. Dolerites of Svalbard, north-west Barents Sea Shelf: age, tectonic setting and significance for geotectonic interpretation of the High-Arctic Large Igneous Province

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    Zoltán Pécskay

    2011-08-01

    Full Text Available The dolerites of Svalbard are mineralogically and geochemically homogeneous with geochemical features typical of continental within-plate tholeiites. Their geochemistry is similar to tholeiites belonging to a bimodal suite defined as the High-Arctic Large Igneous Province (HALIP. K–Ar dating of numerous dolerites sampled from many locations across Svalbard define a narrow time span of this magmatism from 125.5±3.6 to 78.3±2.6 Mya. Discrete peaks of intensive activity occurred at 115.3, 100.8, 91.3 and 78.5 Mya corresponding to (1 breakup of the continental crust and formation of an initial rift as a result of mantle plume activity, located in the southern part of the Alpha Ridge; (2 magmatic activity related to spreading along the Alpha Ridge that led to the development of the initial oceanic crust and (3 continuation of spreading along the Alpha Ridge and termination of magmatic activity related to HALIP (last two peaks at 91.3 and 78.5 Mya.

  5. Nonexplosive and explosive magma/wet-sediment interaction during emplacement of Eocene intrusions into Cretaceous to Eocene strata, Trans-Pecos igneous province, West Texas

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    Befus, K.S.; Hanson, R.E.; Miggins, D.P.; Breyer, J.A.; Busbey, A.B.

    2009-01-01

    Eocene intrusion of alkaline basaltic to trachyandesitic magmas into unlithified, Upper Cretaceous (Maastrichtian) to Eocene fluvial strata in part of the Trans-Pecos igneous province in West Texas produced an array of features recording both nonexplosive and explosive magma/wet-sediment interaction. Intrusive complexes with 40Ar/39Ar dates of ~ 47-46??Ma consist of coherent basalt, peperite, and disrupted sediment. Two of the complexes cutting Cretaceous strata contain masses of conglomerate derived from Eocene fluvial deposits that, at the onset of intrusive activity, would have been > 400-500??m above the present level of exposure. These intrusive complexes are inferred to be remnants of diatremes that fed maar volcanoes during an early stage of magmatism in this part of the Trans-Pecos province. Disrupted Cretaceous strata along diatreme margins record collapse of conduit walls during and after subsurface phreatomagmatic explosions. Eocene conglomerate slumped downward from higher levels during vent excavation. Coherent to pillowed basaltic intrusions emplaced at the close of explosive activity formed peperite within the conglomerate, within disrupted Cretaceous strata in the conduit walls, and within inferred remnants of the phreatomagmatic slurry that filled the vents during explosive volcanism. A younger series of intrusions with 40Ar/39Ar dates of ~ 42??Ma underwent nonexplosive interaction with Upper Cretaceous to Paleocene mud and sand. Dikes and sills show fluidal, billowed, quenched margins against the host strata, recording development of surface instabilities between magma and groundwater-rich sediment. Accentuation of billowed margins resulted in propagation of intrusive pillows into the adjacent sediment. More intense disruption and mingling of quenched magma with sediment locally produced fluidal and blocky peperite, but sufficient volumes of pore fluid were not heated rapidly enough to generate phreatomagmatic explosions. This work suggests that

  6. Joint pre-stack depth migration and travel-time tomography applied to a deep seismic profile across the northern Barents Sea igneous province

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    Minakov, Alexander; Faleide, Jan Inge; Sakulina, Tamara; Krupnova, Natalia; Dergunov, Nikolai

    2015-04-01

    The mainly Permo-Triassic North Barents Sea Basin is considered as a superdeep intracratonic basin containing over 20 km of sedimentary material. This basin was strongly affected by magmatism attributed to the formation of the Early Cretaceous High Arctic Large Igneous Province. Dolerite dikes, sills, and lava flows are observed in the northern Barents Sea and on the islands of Svalbard and Franz Josef Land. Some dike swarms can be traced over hundreds of kilometers using high-resolution airborne magnetic data. In the North Barents Sea Basin, the dikes fed giant sill complex emplaced into organic-rich Triassic siliciclastic rocks. The sill complex creates a major challenge for seismic imaging masking the underlying strata. In this contribution, we first perform refraction and reflection travel-time tomography using wide-angle ocean-bottom seismometer data (with receivers deployed every 10 km) along the 4-AR profile (Sakulina et al. 2007, Ivanova et al. 2011). The resulting tomographic model is then used to construct a background velocity model for the pre-stack depth migration. We show that the use of a combined velocity model for the time and depth imaging based on travel-time tomography and RMS velocities constitutes a substantial improvement with respect to a standard processing workflow providing a more coherent seismic structure of this volcanic province. The interpretation of multichannel seismic and high-resolution magnetic data together with P-wave velocity and density anomalies allow to create a model for the system of magmatic feeders in the crystalline basement of the northern Barents Sea region. Sakulina, T.S., Verba, M.L., Ivanova, N.M., Krupnova, N.A., Belyaev I.V., 2007. Deep structure of the north Barents-Kara Region along 4AR transect (Taimyr Peninsula - Franz Joseph Land). In: Models of the Earth's crust and upper mantle after deep seismic profiling. Proceedings of the international scientific-practical seminar. Rosnedra, VSEGEI. St

  7. Modeling the consequences on late Triassic environment of intense pulse-like degassing during the Central Atlantic Magmatic Province using the GEOCLIM model

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    G. Paris

    2012-06-01

    Full Text Available The Triassic-Jurassic boundary (TJB is associated with one of the five largest mass extinctions of the Phanerozoic. A deep carbon cycle perturbation and a carbonate production crisis are observed during the late Triassic. The Central Atlantic Magmatic Province (CAMP, one of the most important large igneous provinces of the Phanerozoic, emplaced at the TJB. To understand the carbon cycle perturbations observed at the TJB, we investigate the consequences of CO2 degassing associated to the CAMP emplacement on atmospheric and oceanic carbon cycle. The CO2 input within the atmosphere due to volcanism has been modeled using a global biogeochemical cycle box model (COMBINE coupled with a climate model (FOAM. Weathering fluxes and CO2 equilibrium are constrained by the Rhaetian paleogeography and different scenarios of the CAMP emplacement are modeled. The study focuses (1 on the geological record and the carbonate productions crisis and (2 on the sedimentary carbon isotope record. For point (1, comparison of different modeling scenarios shows that a Gaussian CO2 emission distribution over the duration of the main activity phase of the CAMP fails in reproducing any of the geological observations, mainly the carbonate production crisis observed in the late Rhaetian sediments. Contrastingly, intense degassing peaks lead to successive decrease in carbonate production as observed in the geological record. For point (2, the perturbations of carbon cycle due to the degassing of CO2 with a mantellic carbon isotopic composition of −5‰ do not reproduce the intensity of the observed carbon isotope excursions. This was achieved in our model by assuming a mantellic carbon isotopic composition of −20‰. Even if this hypothesis requires further investigations, such low values may be associated to degassing of carbon from pools of light isotopic carbon located at the transition zone (Cartigny, 2010

  8. Hf isotope compositions and chronology of magmatic zircons from Tarim continental flood basalts: implications for magmatic evolution of the Early Permian Tarim Large Igneous Province in NW China

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    Li, Y.; Li, Z.; Yu, X.; Langmuir, C. H.; Yang, S.; Chen, H.

    2013-12-01

    The Early Permian Tarim Large Igneous Province (TLIP) in the Tarim cratonic block of northwestern China has been largely regarded to be genetically linked with a mantle plume. Recently, some euhedral zircon crystals with magmatic growth zoning have been obtained from the Tarim continental flood basalts (TCFB) for detailed U-Pb chronological and genetic study. The zircons have the concordant 206Pb/238U ages of 297~283 Ma, coinciding with the previously reported whole-rock 40K/39Ar and 40Ar/39Ar ages (292~283 Ma) of their host basalts. In-situ LA-MC-ICPMS Lu-Hf isotopic analyses of Early Permian zircons from the Keping area of the TCFB reveal that the zircons from two basalt sub-groups (Groups 1a, 1b) have a narrow range of 176Hf/177Hf ratios between 0.282422 and 0.282568. Their corresponding ɛHf(t) (t = 290 Ma) values (-6.8~-1.4) are generally lower than their host basalts (-2.3~2.1), and distinctively different from the intrusive rocks (3.0~7.1) and their zircons (4.9~8.8) from the TLIP and the Precambrian crustal rocks (extrusion of basalts and been captured as xenocrysts by the rapidly erupted basaltic lavas. Almost the same ɛHf(t) values between the corroded and uncorroded zircons suggest that the zircons have preserved the initial Hf isotopic compositions from their original source region. Moreover, the very close but relatively higher ɛHf(t) values from the zircons than the inferred sub-continental lithospheric mantle (SCLM) beneath Tarim in the Early Permian [ɛHf(t) = -8.7~-5.2; t = 290 Ma] indicate that the zircons were probably originated from the SCLM with minor addition of depleted mantle magmas during the mantle source partial melting. Both the zircons and their host basalts have almost the same formation ages (~290 Ma) and Hf TDM model ages (ca. 1300~1000 Ma), suggesting that they may have a similar mantle source region. The relatively higher ɛHf(t) values of the basalts than zircons further indicate that more depleted mantle components have been

  9. Invasion of the red seaweed Heterosiphonia japonica spans biogeographic provinces in the Western North Atlantic Ocean.

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    Christine Newton

    Full Text Available The recent invasion of the red alga Heterosiphonia japonica in the western North Atlantic Ocean has provided a unique opportunity to study invasion dynamics across a biogeographical barrier. Native to the western North Pacific Ocean, initial collections in 2007 and 2009 restricted the western North Atlantic range of this invader to Rhode Island, USA. However, through subtidal community surveys, we document the presence of Heterosiphonia in coastal waters from Maine to New York, USA, a distance of more than 700 km. This geographical distribution spans a well-known biogeographical barrier at Cape Cod, Massachusetts. Despite significant differences in subtidal community structure north and south of Cape Cod, Heterosiphonia was found at all but two sites surveyed in both biogeographic provinces, suggesting that this invader is capable of rapid expansion over broad geographic ranges. Across all sites surveyed, Heterosiphonia comprised 14% of the subtidal benthic community. However, average abundances of nearly 80% were found at some locations. As a drifting macrophyte, Heterosiphonia was found as intertidal wrack in abundances of up to 65% of the biomass washed up along beaches surveyed. Our surveys suggest that the high abundance of Heterosiphonia has already led to marked changes in subtidal community structure; we found significantly lower species richness in recipient communities with higher Heterosiphona abundances. Based on temperature and salinity tolerances of the European populations, we believe Heterosiphonia has the potential to invade and alter subtidal communities from Florida to Newfoundland in the western North Atlantic.

  10. Contributions of palynology to Carboniferous biostratigraphy and coal geology of the Atlantic provinces of Canada

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    Hacquebard, P.A. [Geological Survey of Canada, Dartmouth, NS (Canada). Atlantic Geoscience Centre

    1997-01-01

    W.A. Bell`s palaeobotanical and geological studies carried out between 1927 and 1948 resulted in the recognition of six stratigraphic units in the Carboniferous system of the Atlantic Provinces of Canada. Subsequent palynological research provided additional information on: (1) The recognition of nineteen miospore zones in the six groups of the Carboniferous succession. (2) Regional correlation of the stratigraphic units in areas where, due to lack of plant megafossils, no age relationship had been established. This resulted in recognizing the existence of the Gulf of St. Lawrence coalfield, the largest in eastern Canada. (3) Detailed coal seam correlations from miospore histograms, as an aid to structural and stratigraphic interpretations, resulted in delineating hitherto unknown coal reserves, notably in the Mabou and Pictou coalfields of Nova Scotia and in the Central Pennsylvanian Basin of New Brunswick. (4) The miospore assemblages provided information on the negotiation of the ancient peat mires that are valuable to coal-facies interpretations.

  11. Epithermal mineralization controlled by synextensional magmatism in the Guazapares Mining District of the Sierra Madre Occidental silicic large igneous province, Mexico

    Science.gov (United States)

    Murray, Bryan P.; Busby, Cathy J.

    2015-03-01

    We show here that epithermal mineralization in the Guazapares Mining District is closely related to extensional deformation and magmatism during the mid-Cenozoic ignimbrite flare-up of the Sierra Madre Occidental silicic large igneous province, Mexico. Three Late Oligocene-Early Miocene synextensional formations are identified by detailed volcanic lithofacies mapping in the study area: (1) ca. 27.5 Ma Parajes formation, composed of silicic outflow ignimbrite sheets; (2) ca. 27-24.5 Ma Témoris formation, consisting primarily of locally erupted mafic-intermediate composition lavas and interbedded fluvial and debris flow deposits; (3) ca. 24.5-23 Ma Sierra Guazapares formation, composed of silicic vent to proximal ignimbrites, lavas, subvolcanic intrusions, and volcaniclastic deposits. Epithermal low-to intermediate-sulfidation, gold-silver-lead-zinc vein and breccia mineralization appears to be associated with emplacement of Sierra Guazapares formation rhyolite plugs and is favored where pre-to-synvolcanic extensional structures are in close association with these hypabyssal intrusions. Several resource areas in the Guazapares Mining District are located along the easternmost strands of the Guazapares Fault Zone, a NNW-trending normal fault system that hosts most of the epithermal mineralization in the mining district. This study describes the geology that underlies three of these areas, which are, from north to south: (1) The Monte Cristo resource area, which is underlain primarily by Sierra Guazapares formation rhyolite dome collapse breccia, lapilli-tuffs, and fluvially reworked tuffs that interfinger with lacustrine sedimentary rocks in a synvolcanic half-graben bounded by the Sangre de Cristo Fault. Deposition in the hanging wall of this half-graben was concurrent with the development of a rhyolite lava dome-hypabyssal intrusion complex in the footwall; mineralization is concentrated in the high-silica rhyolite intrusions in the footwall and along the

  12. 大火成岩省与二叠纪两次生物灭绝关系研究进展%The Link between Large Igneous Provinces and the Two Mass Extinctions in Permian: Review of Recent Progress

    Institute of Scientific and Technical Information of China (English)

    朱江; 张招崇

    2013-01-01

    The two mass extinction events in the Permian, debated and investigated by geologists, have been a hottest of issues. In the Permo-Triassic boundary (PTB, about 252 Ma) mass extinction, more than 90% of marine species went extinct, and biogeochemical cycles were disrupted globally. The other smaller mass extinction occurred at the Guadalupian-Lopingian boundary (GLB, end-Guadalupian, about 260 Ma). Although the origin of the two mass extinction events has been unclear, it is a coincidence that a temporal link between the two mass extinction events and flood basalts volcanisms of the Siberian and Emeishan large igneous provinces. Generally, the volcanism has been considered to be a major cause of mass extinction which caused a sharp deterioration of global climate due to a large quantity of volatile gases and volcanic ash production. This paper reviews, around the coupling relationship between the two mass extinction events and the large igneous provinces, research results of volatile gases release from geological processes associated with large igneous provinces. In the end, we summarize some controversies at the current stage and put forward some suggestions for Emeishan large igneous province.%二叠纪两次生物灭绝事件一直是地质学家所关注和研究的热点问题.一次是地质历史上规模最大的晚二叠世乐平期末生物灭绝事件(Permian-Triassic boundary-PTB,约252 Ma),导致超过95%的海洋物种消失和全球生物化学圈紊乱;另一次是规模相对较小的中二叠世瓜德鲁普期末(end-Guadalupian,Guadalupian-Lopingian boundary-GLB,约260 Ma)生物灭绝事件.尽管这两次生物灭绝的原因尚不完全清楚,但巧合的是,这两次生物灭绝事件在时间上分别与西伯利亚和峨眉山大火成岩省火山活动存在耦合关系.一般认为,火山活动导致生物灭绝主要机制是其产生大量挥发性气体和火山灰引发全球性环境气候急剧恶化的结果.本文回顾近年

  13. Combined 40Ar/39Ar and Fission-Track study of the Freetown Layered Igneous Complex, Freetown, Sierra Leone, West Africa: Implications for the Initial Break-up of Pangea to form the Central Atlantic Ocean and Insight into the Post-rift Evolution of the Sie

    Science.gov (United States)

    Barrie, Ibrahim; Wijbrans, Jan; Andriessen, Paul; Beunk, Frank; Strasser-King, Victor; Fode, Daniel

    2010-05-01

    Sierra Leone lies within the south-western part of the West African Craton and comprises two major Archaean structural divisions: a low-grade granite-greenstone terrane characterised by N-S striking structures and a NW-SE striking highly metamorphosed belt of strained rocks that form the coastal margin of the craton. Intruded into the belt is the Freetown Layered Igneous Complex (FLIC), a tholeiitic magamtic body emplaced prior to or during the break-up of Pangea to form the Central Atlantic Ocean and, forming today the high ground of the coastal outline of Sierra Leone which is one of the most distinctive features on the West African coast. The break-up of Pangaea to form the Central Atlantic and its passive margins began in the Early Jurassic. Geo-tectonically, the break-up was particularly characterised by the formation of the Central Atlantic Magmatic Province (CAMP), covering once-contiguous parts of North America, Europe, Africa and South America. The FLIC forming part of the heart of CAMP is the largest single layered igneous intrusive yet known on either side of the Central Atlantic, measuring on surface, 65 x 14 x 7 km. Geophysical investigations indicate that the intrusion extends offshore to a depth of about 20 km. Geologically the Complex is a rhythmically layered elongated ultramafic-mafic lopolith divisible into 4 major zones each comprising repeated sequences of troctolitic, gabbroic and anorthositic rocks. An idealised unit of layering is from base upwards: dunite, troctolite, olivine-gabbro, leuco-gabbro, gabbro-norite and anorthosite cumulates. 40Ar-39Ar age spectra and 40Ar/36Ar versus 39Ar/36Ar isochron plots obtained by stepwise-heating experiments on plagioclases, biotites and amphiboles from troctolites, olivine-gabbros, gabbro-norites and anorthosites of the four zones yield plateau and isochron ages that seem to depict the cooling history of the Complex after emplacement. The biotites and some of the plagioclases and amphiboles give very

  14. Early-Middle Paleozoic subduction-collision history of the south-eastern Central Asian Orogenic Belt: Evidence from igneous and metasedimentary rocks of central Jilin Province, NE China

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    Pei, Fu-Ping; Zhang, Ying; Wang, Zhi-Wei; Cao, Hua-Hua; Xu, Wen-Liang; Wang, Zi-Jin; Wang, Feng; Yang, Chuan

    2016-09-01

    To constrain the Early-Middle Paleozoic tectonic evolution of the south-eastern segment of the Central Asian Orogenic Belt (CAOB), we undertook zircon U-Pb dating and analyzed major and trace elements and zircon Hf isotope compositions of Late Cambrian to Middle Devonian igneous and metasedimentary rocks in central Jilin Province, NE China. LA-ICP-MS zircon U-Pb dating indicates that the Early-Middle Paleozoic magmatism in central Jilin Province can be divided into four episodes: Late Cambrian (ca. 493 Ma), Middle Ordovician (ca. 467 Ma), Late Ordovician-Early Silurian (ca. 443 Ma), and Late Silurian-Middle Devonian (425-396 Ma). The progression from subduction initiation to maturity is recorded by Late Cambrian low-K tholeiitic meta-diabase, Middle Ordovician medium-K calc-alkaline pyroxene andesite, and Late Ordovician to Early Silurian low-K tonalite, which all have subduction-related characteristics and formed in an evolving supra-subduction zone setting. Late Silurian to Middle Devonian calc-alkaline igneous rocks, with the lithological association of granodiorite, monzogranite, rhyolite, dacite, and trachydacite, show progressively increasing K2O contents from medium K to shoshonite series. Furthermore, the Early-Middle Devonian monzogranites are characterized by high K2O, Sr/Y, and [La/Yb]N values, indicating they were generated by the melting of thickened lower crust. These results suggest a transition from subduction to post-orogenic setting during the Late Silurian-Middle Devonian. Our interpretation is supported by the maximum age of molasse deposition in the Zhangjiatun member of the Xibiehe Formation. Overall, we suggest that Late Cambrian tholeiitic meta-diabase, Middle Ordovician pyroxene andesite, and Late Ordovician-Early Silurian tonalite formed above the northward-subducting and simultaneously seaward-retreating of Paleo-Asian Ocean plate. Subsequently, the northern arc collided with the North China Craton and post-orogenic extension occurred

  15. Two new Mycale (Naviculina Gray (Mycalidae, Poecilosclerida, Demospongiae from the Paulista Biogeographic Province (Southwestern Atlantic

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    Cléa Lerner

    2002-03-01

    Full Text Available Two new Mycale (Naviculiiia Gray, 1867 are described, M. (N. arcuiris sp. n. and M. (N.purpurata sp. n., from the Paulista Biogeographic Province (Southwestern Atlantic. They both occur in the São Sebastião Channel area (São Paulo stale coast, the former extending its known distribution to "Arvoredo Marine Biological Reserve" (Santa Catarina state coast. The new species are sibling and differ from each other by a series of very small traits, the most notorious being live-color: yellow, orange, green, white, grey and beige, always light, in M. (N. arcuiris sp. n. and bordeaux in M. (N. purpúrala sp. n. Both species are compared with other known M. (Naviculiiia. Mycale (Aegogropila henlscheli Sim & Lee, 2001 is transferred to subgenus Naviculiiia and given a new name, viz. M. (N. chungue nom. n., as the specific name was preoccupied by M. (Curmia henlscheli Bergquist & Fromont, 1988. An identification key for all the species hitherto assigned to the subgenus is provided.

  16. The role of igneous and metamorphic processes in triggering mass extinctions and Earth crises

    Science.gov (United States)

    Svensen, Henrik; Planke, Sverre; Polozov, Alexander G.; Jerram, Dougal; Jones, Morgan T.

    2016-04-01

    Mass extinctions and transient climate events commonly coincide in time with the formation of Large igneous provinces (LIPs). The end-Permian event coincides with the Siberian Traps, the end-Triassic with the Central Atlantic Magmatic Event (CAMP), the Toarcian with the Karoo LIP, and the Paleocene-Eocene Thermal Maximum (PETM) with the North Atlantic Igneous Province. Although the temporal relationship between volcanism and the environmental crises has been known for decades, the geological processes linking LIPs to these environmental events are strongly debated: Explosive LIP volcanism should lead to short term cooling (not long term warming), mantle CO2 is too 13C-enriched to explain negative 13C carbon isotope excursions from sedimentary sequences, the LIP volcanism is poorly dated and apparently lasts much longer that the associated environmental events, large portions of the LIPs remain poorly explored, especially the sub-volcanic parts where sills and dikes are emplaced in sedimentary host rocks, and thus gas flux estimates from contact aureoles around sill intrusions are often poorly constrained. In this presentation, we discuss the status of LIP research with an emphasis on the sub volcanic processes. We show that potential for degassing of greenhouse gases, aerosols, and ozone destructive gases is substantial and can likely explain the triggering of both climatic events and mass extinctions.

  17. Multiple shallow level sill intrusions coupled with hydromagmatic explosive eruptions marked the initial phase of Ferrar large igneous province magmatism in northern Victoria Land, Antarctica

    Science.gov (United States)

    Viereck-Goette, L.; Schöner, R.; Bomfleur, B.; Schneider, J.

    2007-01-01

    Field data gathered during GANOVEX IX (2005/2006) in Northern Victoria Land, Antarctica, indicate that volcaniclastic deposits of phreatomagmatic eruptions (so-called Exposure Hill Type events) are intercalated with fluvial deposits of Triassic-Jurassic age at two stratigraphic levels. Abundant scoriaceous spatter (locally welded) indicates a hawaiian/strombolian component. Breccia-filled diatremes, from which volcaniclastic deposits were sourced, are rooted in sills which intruded wet sediments. The deposits are thus subaerial expressions of initial Ferrar magmatism involving intrusion of multiple shallow-level sills. Due to magma-sediment interaction abundant clastic dikes are developed that intrude the sediments and sills. All igneous components in the volcaniclastic deposits are andesitic in composition, as are the chilled margins of the sills. They are more differentiated than the basaltic andesites of the younger effusive section of Kirkpatrick plateau lavas which in northern Victoria Land start with pillow lavas and small volume lava flows from volcanic necks.

  18. Late Carboniferous cyclothems in Atlantic Canada and event correlation in the Euramerican Coal Province

    Energy Technology Data Exchange (ETDEWEB)

    Gibling, M.R. (Dalhousie Univ., Halifax, Nova Scotia (Canada). Dept. of Earth Sciences)

    1992-01-01

    The Maritimes Basin of Atlantic Canada contains a thick Late Carboniferous succession and is interposed between US and European coal basins. In the Sydney coalfield of the Maritimes Basin, events of probable regional significance are recorded in ten mid Westphalian D to early Stephanian cyclothems, 20--70 m thick and about 2--300,000 years in mean duration. Coals up to 4.3 m thick are associated with coastal sandstones/shales and are overlain by thin black shales/limestones; agglutinated foraminifera indicate restricted marine conditions. Coal-bearing units alternate with alluvial-plain deposits that include red mudstones formed as mature paleosols in a strongly season climate. Stacked alluvial channel bodies above some coals are interpreted as paleovalley fills that reflect incision and subsequent aggradation, probably related to relative sea-level fluctuation associated with Gondwanan glaciation. Red strata predominate and coals become uneconomic higher in the Stephanian as Euramerican climates became more continental. Coeval coal-bearing strata (and, probably, cyclothems) also underlie large areas of the Gulf of St. Lawrence which, together with the Sydney region, is about 80,000 km[sup 2] in area. Biostratigraphic studies indicate that the Westphalian D to early Stephanian correlates with the Desmoinesian/Missourian of the interior US. The Maritimes Basin cyclothems are thus coeval with cylothemic intervals in the Midcontinental, Illinois and Appalachian Basins that include major economic seams (Herrin No. 6, springfield No. 5, Freeport, Kittanning). Although the level of biostratigraphic resolution currently precludes precise correlation, cyclothem-generating events probably influenced and may be traceable in coastal plain settings through much of the Euramerican Coal Province in the latest Carboniferous.

  19. Evolution of the Mazatzal province and the timing of the Mazatzal orogeny: Insights from U-Pb geochronology and geochemistry of igneous and metasedimentary rocks in southern New Mexico

    Science.gov (United States)

    Amato, J.M.; Boullion, A.O.; Serna, A.M.; Sanders, A.E.; Farmer, G.L.; Gehrels, G.E.; Wooden, J.L.

    2008-01-01

    New U-Pb zircon ages, geochemistry, and Nd isotopic data are presented from three localities in the Paleoproterozoic Mazatzal province of southern New Mexico, United States. These data help in understanding the source regions and tectonic setting of magmatism from 1680 to 1620 Ma, the timing of the Mazatzal orogeny, the nature of postorogenic maginatism, Proterozoic plate tectonics, and provide a link between Mazatzal subblocks in Arizona and northern New Mexico. The data indicate a period from 1680 to 1650 Ma in which juvenile felsic granitoids were formed, and a later event between 1646 and 1633 Ma, when these rocks were deformed together with sedimentary rocks. No evidence of pre-1680 Ma rocks or inherited zircons was observed. The igneous rocks have ENd(t) from -1.2 to +4.3 with most between +2 and +4, suggesting a mantle source or derivation from similar-aged crust. Nd isotope and trace element concentrations are consistent with models for typical are magmatism. Detrital zircon ages from metasedimentary rocks indicate that sedimentation occurred until at least 1646 Ma. Both local and Yavapai province sources contributed to the detritus. All of the samples older than ca. 1650 Ma are deformed, whereas undeformed porphyroblasts were found in the contact aureole of a previously dated 1633 Ma gabbro. Regionally, the Mlazatzal orogeny occurred mainly between 1654 and 1643 Ma, during final accretion of a series of island arcs and intervening basins that may have amalgamated offshore. Rhyolite magmatism in the southern Mazatzal province was coeval with gabbro intrusions at 1633 Ma and this bimodal magmatism may have been related to extensional processes following arc accretion. ?? 2007 Geological Society of America.

  20. Geophysical and geodynamic studies of the North Atlantic Realm

    DEFF Research Database (Denmark)

    Schiffer, Christian

    2015-01-01

    Atlantic, such as the occurrence of the Iceland Melt Anomaly and the North Atlantic Igneous Province, as well as the separation from the Jan Mayen microcontinent (P4). Finally a novel modelling approach was developed to iteratively improve predictions of the lithospheric geopotential stress field with......The geology of the North Atlantic Realm (NAR), including the North Atlantic, Greenland, the Arctic, Iceland, Scandinavia, Northern Europe and Northeast America has been studied for more than a century and inspired some of the most fundamental theories in geoscience, such as plate tectonics, the...... mountain range (approx. 425 Ma), the exact series and number of collision and subduction events as well as subduction polarity. b) The formation of the North Atlantic (approx. 60 Ma) and accompanied high magmatic activity which formed distinct and conspicuous structures and features, such as the Iceland...

  1. Petrology and U-PB geochronology of the Robertson River Igneous Suite, Blue Ridge province, Virginia - Evidence for multistage magmatism associated witn an early episode of Laurentian rifting

    Science.gov (United States)

    Tollo, R.P.; Aleinikoff, J.N.

    1996-01-01

    The Late Neoproterozoic (735-702 Ma) Robertson River Igneous Suite includes at least eight plutons ranging in composition from syenogranite to alkali feldspar granite to alkali feldspar syenite. These plutons intruded Mesoproterozoic (1.2-1.0 Ga) gneissic basement of the Blue Ridge anticlinorium in northern and central Virginia during an early episode of Laurentian rifting. Robertson River plutons range in composition from metaluminous to peralkaline and, relative to other granite types, exhibit compositional characteristics of A-type granitoids including (1) marked enrichment in Nb, Zr, Y, REE (except Eu), and Ga, (2) high Ga/Al and FeO(total)/MgO, and (3) depletion of Ba and Sr. High Ga/Al ratios are particularly diagnostic of the suite and serve as an effective discriminant between originally metaluminous and peralkaline bulk compositions, providing a useful proxy for widely used indicators based on major elements that are prone to remobilization. U-Pb isotopic analyses of zircons indicate that the suite was emplaced in two pulses, occurring at 735 to 722 and 706 to 702 Ma. Metaluminous magmas were emplaced during both pulses, formed most of the main batholith, and fractionated as independent, time-correlative groups. Peralkaline magmas were emplaced only during the final pulse, formed a volcanic center that erupted unknown quantities of rhyolite, and experienced a style of fractionation similar to the metaluminous types. Differences in Ce/Nb, Y/Nb, and Yb/Ta ratios suggest that the metaluminous and peralkaline magmas were derived from different sources. The Robertson River Igneous Suite is part of a regional group of Late Neoproterozoic (760-700 Ma) plutons including at least 20 other A-type granitoid bodies exposed throughout the Laurentian terrane of Virginia and northwestern North Carolina. Like the Robertson River, most of the other granitoids are metaluminous in composition, typically form multi-intrusive, elongate plutons, and are not geographically

  2. Lead isotopic systematics for native copper-chalcocite mineralization in basaltic lavas of the Emeishan large igneous province, SW China:Implications for the source of copper

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qian; WANG Dapeng; ZHU Xiaoqing; ZHANG Zhengwei; ZHU Chaohui

    2009-01-01

    The Emeishan continental flood basalt, which is widespread in Yunnan, Guizhou and Sichuan provinces of Southwest China, is the volcanic product of a Permian mantle plume, and native copper-chalcocite mineralization associated with the basalt is very common in the border area of Yunnan and Guizhou provinces. The mineralization occurred in the tuff intercalation and terrestrial sedimentary rock intercalation which were formed during the main period of basalt eruption. The orebodies are controlled by the stratigraphic position and faults. Metal ore minerals in the ores are mainly native copper, chalcocite and tenorite, with small amounts of chalcopyrite, bomite, pyrite and malachite, and sometimes with large amounts of bitumen, carbon and plant debris. Several decades of ore deposits are distributed in the neighboring areas of the two provinces, while most of them are small-scale deposits or only ore occurrences. By comparing the lead isotopic composition of the ores with that of the wall-rocks, cover and basement rocks of various periods, the source of copper in this type of ore deposits was studied in this paper. The results showed that: (1) The Pb isotopic composition of the ores from ten deposits is absolutely different from that of sili-ceous-argillaceus rocks of the Upper Permian Xuanwei Formation, limestones of the Lower Permian Series and Carboniferous, Cambrian sandstone-shale and recta-sedimentary rock and dolomite from the upper part of the Meso-Proterozoic Kunyang Group, This indicates that ore lead was derived neither from the cover rock nor from the basement rocks; (2) Although the Neo-Proterozoic Siman dolomite and silicalite, and dolomite in the lower part of the Kunyang Group are similar in Pb isotopic composition to the ores, lead and copper contents in these rocks are very low and they have not made great contributions to copper mineralization; (3) The ores have the same Pb iso-topic composition as the basalt, the latter being enriched in copper

  3. Biogeographic provinces in the Atlantic deep sea determined from cumacean distribution patterns

    Science.gov (United States)

    Watling, Les

    2009-09-01

    Cumacean species abundance and presence-absence data were compiled from samples taken along the US northeast slope and rise, from around the Faroe Islands, and from deep-sea transects throughout the Atlantic Ocean. These data were analyzed using hierarchical cluster techniques, the results being used to help determine the boundaries of zoogeographic units in the deep sea. Comparing the results of these analyses with previous studies on protobranchs, tunicates, and sea stars, supports dividing the deep Atlantic Ocean into the following biogeographic units: (1) Norwegian Basin; (2) North Atlantic Upper Bathyal; (3) West European Basin Northern Bathyal; (4) Lusitanian Bathyal; (5) North American Basin Bathyal; (6) West European Basin Abyssal; (7) North American Basin Abyssal; and (8) Angola, Cape, Brazil, and Argentine Basins occupying the more or less isolated basins of the South Atlantic Ocean. These latter are not well-sampled for most groups but appear to be separated from each other.

  4. Origin and evolution of overlapping calc-alkaline and alkaline magmas: The Late Palaeozoic post-collisional igneous province of Transbaikalia (Russia)

    Science.gov (United States)

    Litvinovsky, B. A.; Tsygankov, A. A.; Jahn, B. M.; Katzir, Y.; Be'eri-Shlevin, Y.

    2011-08-01

    The Late Palaeozoic voluminous magmatism in Transbaikalia, Russia (a territory of > 600,000 km 2 to the east of Lake Baikal) is highly diverse and complex. Of special interest are (1) the significant overlap in time between magmatic suites commonly ascribed to post-collisional and within-plate settings and (2) the provenance of the coeval, but distinct, granitoid magmas that are closely spaced within a large region. Magmatic activity lasted almost continuously from ~ 330 Ma to ~ 275 Ma and included five igneous suites occupying a total area of ~ 200,000 km 2: (1) the Barguzin suite of high-K calc-alkaline granite (330-310 Ma); (2 and 3) the coeval Chivyrkui suite of low-silica calc-alkaline granitoids and the Zaza suite of high-K calc-alkaline to alkaline granite and quartz syenite which were emplaced between 305 and 285 Ma; and (4 and 5) the partially overlapped in time Lower-Selenga monzonite-syenite suite (285-278 Ma) and the Early-Kunalei suite of alkali-feldspar and peralkaline quartz syenite and granite (281-275 Ma). The overall increase in alkalinity of the granitoids with time reflects the progress from post-collisional to within-plate settings. However, a ~ 20 m.y. long transitional period during which both calc-alkaline and alkaline granitoids were emplaced indicates the coexistence of thickened (batholiths) and thinned (rift) crustal tracts. Sr-Nd-O isotope and elemental geochemical data suggest that the relative contribution of mantle-derived components to the generation of silicic magmas progressively increased with time. The high-K calc-alkaline granite magmas that formed the Angara-Vitim batholith were generated by high degree melting of supracrustal metamorphic rocks [ɛNd(t) = - 5.7 to - 7.7; δ 18O(Qtz) = 12‰], with minor contribution of H 2O and K from the underplated mafic magma (the convective diffusion model). The coeval calc-alkaline Chivyrkui suite and the transitional to alkaline Zaza suite formed as a result of mixing of crustal silicic

  5. Comparison of Cenozoic Faulting at the Savannah River Site to Fault Characteristics of the Atlantic Coast Fault Province: Implications for Fault Capability

    Energy Technology Data Exchange (ETDEWEB)

    Cumbest, R.J.

    2000-11-14

    This study compares the faulting observed on the Savannah River Site and vicinity with the faults of the Atlantic Coastal Fault Province and concludes that both sets of faults exhibit the same general characteristics and are closely associated. Based on the strength of this association it is concluded that the faults observed on the Savannah River Site and vicinity are in fact part of the Atlantic Coastal Fault Province. Inclusion in this group means that the historical precedent established by decades of previous studies on the seismic hazard potential for the Atlantic Coastal Fault Province is relevant to faulting at the Savannah River Site. That is, since these faults are genetically related the conclusion of ''not capable'' reached in past evaluations applies.In addition, this study establishes a set of criteria by which individual faults may be evaluated in order to assess their inclusion in the Atlantic Coast Fault Province and the related association of the ''not capable'' conclusion.

  6. Late Permian basalts in the northwestern margin of the Emeishan Large Igneous Province: Implications for the origin of the Songpan-Ganzi terrane

    Science.gov (United States)

    Li, Hongbo; Zhang, Zhaochong; Santosh, M.; LÜ, Linsu; Han, Liu; Liu, Wei; Cheng, Zhiguo

    2016-07-01

    SHRIMP zircon U-Pb ages, geochemical and Sr-Nd isotopic data are reported for two types of basalts (Type I and Type II) from a Permian volcanic-pyroclastic succession in the Tubagou section, Baoxing area along the southeastern margin of the Songpan-Ganzi terrane (SGT) in the Sichuan province of SW China. Zircons from the uppermost basaltic flows yield crystallization age of 257.3 ± 2.0 Ma, which may represent the time of culmination the basaltic eruption. Type I shows alkaline affinity with εNd(t) values of + 2.4 to + 2.9, and is characterized by oceanic island basalt (OIB)-type light rare earth element (LREE) and trace-element patterns. In contrast, Type II rocks are tholeiitic, and close to initial rift tholeiite (IRT)-like REE and trace element patterns, and are relatively depleted in highly incompatible elements with slightly negative Nb-Ta anomaly. The εNd(t) values of Type II are between + 1.8 to + 2.2. The geochemical characteristics suggest the Type I has not been significantly crustally contaminated, whereas Type II maybe have experienced minor crustal contamination. Clinopyroxene crystallization temperature is ~ 80-120°C higher than that of the normal asthenospheric mantle, implying anomalous thermal input from mantle source and a possible plume-head origin for the Tubagou lava. The geochemical and isotopic fes, reflecting progressive lithosphere thinning probably through plume-lithosphere interaction. The spatial and temporal coincidence between the Dashibao basalt eruptions, reflecting progressive lithosphere thinning probably through plume-lithosphere interaction. The spatial and temporal coincidence between the Dashibao basalt eruption and continental rifting suggest that continental break-up and the opening of an extensional basin was probably related to the Late Permian Emeishan plume, which triggered the breakup between the SGT and the Yangtze craton.

  7. Zircon U-Pb geochronology links the end-Triassic extinction with the Central Atlantic Magmatic Province.

    Science.gov (United States)

    Blackburn, Terrence J; Olsen, Paul E; Bowring, Samuel A; McLean, Noah M; Kent, Dennis V; Puffer, John; McHone, Greg; Rasbury, E Troy; Et-Touhami, Mohammed

    2013-05-24

    The end-Triassic extinction is characterized by major losses in both terrestrial and marine diversity, setting the stage for dinosaurs to dominate Earth for the next 136 million years. Despite the approximate coincidence between this extinction and flood basalt volcanism, existing geochronologic dates have insufficient resolution to confirm eruptive rates required to induce major climate perturbations. Here, we present new zircon uranium-lead (U-Pb) geochronologic constraints on the age and duration of flood basalt volcanism within the Central Atlantic Magmatic Province. This chronology demonstrates synchroneity between the earliest volcanism and extinction, tests and corroborates the existing astrochronologic time scale, and shows that the release of magma and associated atmospheric flux occurred in four pulses over about 600,000 years, indicating expansive volcanism even as the biologic recovery was under way. PMID:23519213

  8. The French Guyana doleritic dykes: geochemical evidence of three populations and new data for the Jurassic Central Atlantic Magmatic Province

    Science.gov (United States)

    Nomade, S.; Pouclet, A.; Chen, Y.

    2002-12-01

    A petrographic and geochemical study of 15 Early Jurassic and 7 Proterozoic dolerites of French Guyana, and of one Jurassic dolerite from Ivory-Coast were carried out. The Early Jurassic SSW-NNE trending dykes have doleritic aphyric or gabbroic phyric texture. Their chemical compositions, slightly under-saturated to over-saturated, show moderate to low Mg-ratios (63-36), high TiO 2 contents (1.85-3.56 wt.%), weak rare earth element fractionation [1.8isotopic data of Bertrand et al. [Bertrand, H., Liegeois, J.P., Deckart, K., Féraud, G., 1999. High-Ti tholeiites in Guinea and Their Connection with the Central Atlantic CFB Province: Elemental and Nd-Sr-Pb Isotopic Evidence for Preferential Zone of Mantle Upwelling in Cause of Rifting. AGU spring meeting (Abst. p 317)] suggest that their magmatic source is different from that of the other basalts of the Central Atlantic Magmatic Province (CAMP). Such signatures are restricted to a central zone coinciding with the Panafrican Rokelides suture. We propose a model of sub-lithospheric preferential channelling of an asthenospheric ascent in this zone. Two other groups of dykes were identified in French Guyana. Compared to the Jurassic ones the Proterozoic dykes have NNW-SSE and E-W trending direction, more important LILE enrichment, low TiO 2 contents (<2 wt%) and Nb-Ta negative anomalies. Their calc-alkaline signature could be the result of a previous subduction and may be related to the 1800 Ma Venturi-Tapajós event, which contaminated the mantle source.

  9. The basaltic volcanism of the Dumisseau Formation in the Sierra de Bahoruco, SW Dominican Republic: A record of the mantle plume-related magmatism of the Caribbean Large Igneous Province

    Science.gov (United States)

    Escuder-Viruete, Javier; Joubert, Marc; Abad, Manuel; Pérez-Valera, Fernando; Gabites, Janet

    2016-06-01

    The basaltic volcanism of the Dumisseau Fm in the Sierra de Bahoruco, SW Dominican Republic, offers the opportunity to study, on land, the volcanism of the Caribbean Large Igneous Province (CLIP). It consists of an at least 1.5 km-thick sequence of submarine basaltic flows and pyroclastic deposits, intruded by doleritic dykes and sills. Three geochemical groups have been identified: low-Ti tholeiites (group I); high-Ti transitional basalts (group II); and high-Ti and LREE-enriched alkaline basalts (group III). These geochemical signatures indicate a plume source for all groups of basalts, which are compositionally similar to the volcanic rocks that make up various CLIP fragments in the northern region of the Caribbean Plate. Trace element modelling indicates that group I magmas are products of 8-20% melting of spinel lherzolite, group II magmas result 4-10% melting of a mixture of spinel and garnet lherzolite, and group III basalts are derived by low degrees (0.05-4%) of melting of garnet lherzolite. Dynamic melting models suggest that basalts represent aggregate melts produced by progressive decompression melting in a mantle plume. There is no compositional evidence for the involvement of a Caribbean supra-subduction zone mantle or crust in the generation of the basalts. Two 40Ar/39Ar whole-rock ages reflect the crystallisation of group II magmas at least in the late Campanian (~ 74 Ma) and the lower Eocene (~ 53 Ma). All data suggest that the Dumisseau Fm is an emerged fragment of the CLIP, which continues southward through the Beata Ridge

  10. Zircon U-Pb dating, geochemistry and Sr-Nd-Pb-Hf isotopes of the Wajilitag alkali mafic dikes, and associated diorite and syenitic rocks: Implications for magmatic evolution of the Tarim large igneous province

    Science.gov (United States)

    Zou, Si-Yuan; Li, Zi-Long; Song, Biao; Ernst, Richard E.; Li, Yin-Qi; Ren, Zhong-Yuan; Yang, Shu-Feng; Chen, Han-Lin; Xu, Yi-Gang; Song, Xie-Yan

    2015-01-01

    The Early Permian Tarim large igneous province (Tarim LIP) consists mainly of basaltic lavas, mafic-ultramafic intrusions including dikes and, syenite bodies in the Tarim Basin, NW China. A major unit of the Tarim LIP, the Wajilitag intrusive complex, consists of olivine pyroxenite, clinopyroxenite and gabbro units (from bottom to top), diorite and syenite rocks occurred in the upper part of the complex and alkali mafic dikes intrude the clinopyroxenite phase. Here we report the zircon U-Pb age and Hf isotopes, geochemical characteristics and Sr-Nd-Pb isotopic data of the alkali mafic dikes, and diorite, aegirine-nepheline syenite and syenite porphyry units in the Wajilitag intrusive complex. Zircons from the diorite and alkali mafic rocks yield concordant crystallization ages of 275.2 ± 1.2 Ma and 281.4 ± 1.7 Ma, respectively. The diorite and syenitic rocks in Wajilitag area have a narrow range of SiO2 contents (51.9-57.3 wt.%), and are enriched in total alkalis (Na2O + K2O = 8.3-14.3 wt.%), among which the aegirine-nepheline syenite and syenite porphyry have the geochemical affinity of A-type granites. The alkali mafic rocks and syenitic rocks have high Al2O3 (19.4-21.1 wt.%), Zr, Hf, Ba contents, total rare earth element abundances and LREE/HREE ratios and low Mg# value, K, P and Ti contents. Diorites have lower Al2O3 contents, total REE abundances and LREE/HREE ratios and higher Mg# values than the alkali mafic rocks and syenitic rocks. The diorites and syenitic rocks have low initial 87Sr/86Sr ratios (0.7034-0.7046), and high εNd(t) values (0.1-4.1) and zircon εHf(t) values (- 0.9-4.4). All the diorites and syenitic rocks show the 206Pb/204Pb ratios ranging of 18.0-19.5, 207Pb/204Pb of 15.4-15.6 and 208Pb/204Pb of 38.0-39.9. Sr-Nd isotopic ratios indicate a FOZO-like mantle source for the diorite and syenitic rocks, similar to that of the mafic-ultramafic rocks in the Wajilitag complex. In contrast, zircon Hf isotopes of basalt and syenite elsewhere in the

  11. Shelf north of Falklands may be new S. Atlantic petroleum province

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, S. (Quad Consulting Ltd., Bucks (United Kingdom)); Johnson, M. (Spectrum Energy and Information Technology Ltd., Woking (United Kingdom))

    1995-03-06

    Interpretation of new seismic data shows that all the elements of a favorable petroleum geology exist on the North Falkland shelf and therefore that the area will become an important petroleum province of the future. Spectrum Energy and Information Technology Ltd. acquired approximately 7,500 line km of speculative seismic data during 1993--94 over the continental shelf north of the Falkland Islands. These data have been interpreted geologically to determine the petroleum prospectivity of the area prior to the planned offshore Falkland Islands licensing round. In this article the authors outline this interpretation and show how it provides some important new information on regional geology and the break-up history of southern Gondwana. The paper describes plate tectonics and basin evolution; stratigraphy; basin structure; petroleum geology; source rock maturity; hydrocarbon generation; and petroleum prospectivity.

  12. Holocene explosive volcanism of the Jan Mayen (island) volcanic province, North-Atlantic

    Science.gov (United States)

    Gjerløw, Eirik; Haflidason, H.; Pedersen, R. B.

    2016-07-01

    The volcanic island Jan Mayen, located in the Norwegian-Greenland Sea, hosts the active stratovolcano of Beerenberg, the northernmost active subaerial volcano in the world. At least five eruptions are known from the island following its discovery in the 17th century, but its eruptive history prior to this is basically unknown. In this paper two sediment cores retrieved close to Jan Mayen have been studied in detail to shed light on the Holocene history of explosive volcanism from the Jan Mayen volcanic province. Horizons with elevated tephra concentrations were identified and tephra from these was analysed to determine major element chemistry of the tephra. The tephra chemistry was used to provide a link between the two cores and the land based tephra records from Jan Mayen Island. We managed to link two well-developed tephra peaks in the cores by their geochemical composition and age to Jan Mayen. One of these peaks represents the 1732 AD eruption of Eggøya while the other peak represents a previously undescribed eruption dated to around 10.3 ka BP. Two less prominent tephra peaks, one in each core, dated to approximately 2.3 and 3.0 ka BP, also have a distinct geochemical character linking them to Jan Mayen volcanism. However, the most prominent tephra layer in the cores located close to Jan Mayen and numerous other cores along the Jan Mayen ridge is the 12.1 ka BP Vedde Ash originating from the Iceland volcanic province. We find that the Holocene volcanism on Jan Mayen is much less explosive than volcanism in Iceland, and propose that either low amounts of explosive volcanic activity from the summit region of Beerenberg or small to absent glacier cover on Beerenberg is responsible for this.

  13. Overlapping Sr-Nd-Hf-O isotopic compositions in Permian mafic enclaves and host granitoids in Alxa Block, NW China: Evidence for crust-mantle interaction and implications for the generation of silicic igneous provinces

    Science.gov (United States)

    Dan, Wei; Wang, Qiang; Wang, Xuan-Ce; Liu, Yu; Wyman, Derek A.; Liu, Yong-Sheng

    2015-08-01

    In general, the mantle provides heat and/or material for the generation of the silicic igneous provinces (SIPs). The rarity of mafic microgranular enclaves (MMEs), however, hampers understanding of the mantle's role in generating SIPs and the process of crust-mantle interaction. The widespread distributed MMEs in the newly reported Alxa SIP provide an opportunity to study these processes. This study integrates in situ zircon U-Pb age and Hf-O isotope analyses, whole-rock geochemistry and Sr-Nd isotope results for the MMEs and host granitoids in the Alxa Block. SIMS zircon U-Pb dating reveals that there are two generations of MMEs and host granitoids. The MMEs in the Bayannuoergong batholith were formed at ca. 278 Ma, similar to the age (280 Ma) of host granitoids, and the MMEs and host granitoids in the Yamaitu pluton were formed at ca. 272-270 Ma. All MMEs have relatively low SiO2 (50.7-61.4 wt.%) and Th (0.8-2.8 ppm), but relatively high MgO (2.6-4.9 wt.%), Cr (23-146 ppm) and Ni (6-38 ppm) contents compared to the host granitoids, with SiO2 (63.6-77.5 wt.%), Th (5.2-41 ppm), MgO (0.23-2.1 wt.%), Cr (10-38 ppm) and Ni (5-14 ppm). All MMEs have whole rock Sr-Nd and zircon Hf-O isotope compositions similar to their corresponding host granitoids. The 280 Ma MMEs have lower whole rock εNd(t) (- 13.5) and higher initial 87Sr/86Sr values (0.7095) and zircon δ18O values (6.3‰) compared to the εNd(t) (- 11.5), initial 87Sr/86Sr values (0.7070) and zircon δ18O values (5.6‰) of the 270 Ma MMEs. The occurrences of quartz xenocrysts, K-feldspar megacrysts, corroded feldspars and acicular apatites indicate that the MMEs are the products of the mixing between mantle- and crust-derived magmas. The striking similarities in the zircon Hf-O isotopic compositions in both MME-host granitoid pairs indicate that the granitoids and MMEs have similar sources. The granitoids are proposed to be mainly sourced from magmas generated by remelting of newly formed mafic rocks, which

  14. Petrology of the igneous rocks

    Science.gov (United States)

    Mccallum, I. S.

    1987-01-01

    Papers published during the 1983-1986 period on the petrology and geochemistry of igneous rocks are discussed, with emphasis on tectonic environment. Consideration is given to oceanic rocks, subdivided into divergent margin suites (mid-ocean ridge basalts, ridge-related seamounts, and back-arc basin basalts) and intraplate suites (oceanic island basalts and nonridge seamounts), and to igneous rocks formed at convergent margins (island arc and continental arc suites), subdivided into volcanic associations and plutonic associations. Other rock groups discussed include continental flood basalts, layered mafic intrusions, continental alkalic associations, komatiites, ophiolites, ash-flow tuffs, anorthosites, and mantle xenoliths.

  15. Isotopic Constraints on the Generation of Voluminous Felsic Magmas During the Early Evolution of the Palaeocene Rum Igneous Centre, Scotland.

    Science.gov (United States)

    Nicoll, G. R.; Troll, V. R.; Donaldson, C. H.; Ellam, R. M.; Emeleus, H.

    2006-12-01

    The Isle of Rum is one of several igneous centers within the British-Irish Palaeocene Igneous Province formed during crustal stretching and thinning, prior to the opening of the North Atlantic. An elliptical ring fault, 12km across, bounds the igneous centre enclosing remnants of an early felsic phase (stage 1, [1]). These consist of extrusive rhyodacitic ignimbrites (>100m thick, >10km3 [2]) and various dacitic to rhyolitic shallow- level intrusions (16km2) that are all located close to the ring fault. This early felsic phase of activity is cross-cut by basic and ultrabasic layered intrusions that comprise the Layered Suite (stage 2, [1]). Pre-dating both stages is the intrusion of a very coarse gabbro, now preserved as large blocks within some of the felsic intrusions. Pb isotope ratios (206Pb/204Pb 18.32, ^{208}Pb/204Pb 38.1) suggest this gabbro to be derived from a similar material to the proposed North Atlantic End Member [3] (206Pb/207Pb 17.4 ^{208}Pb/204Pb 37.5). In contrast, the more voluminous felsic phase shows a strong involvement of crustal material with isotopic data implying 60-80% contamination of mantle-derived magmas by upper crustal Lewisian amphibolite gneiss. 87Sr/86Sr isotope data from lobate inclusions and basaltic margins to some of the felsic intrusions, indicate mantle-like values but also show varying levels of crustal contamination (0.7029 - 0.7140). Rare inclusions of coarse feldspathic peridotite are also found within some of the earliest felsic rocks. The combined evidence from the early gabbro intrusions, basaltic margins and the felsic rocks lead us to a model for felsic magma generation in which basic and ultrabasic intrusions at depth, migrating towards the surface, heat and partially melt the surrounding crust, giving rise to a voluminous, but ultimately short-lived episode of felsic magmatism. 1. Emeleus, 1997, Memoir of the BGS, Sheet 60, Scotland. 2. Troll et al., 2000, Bulletin of Volcanology, Vol. 62. 3. Ellam and Stuart

  16. Probable changes in lake chemistry in Canada’s Atlantic Provinces under proposed North American emission reductions

    Directory of Open Access Journals (Sweden)

    T. A. Clair

    2003-01-01

    Full Text Available Atlantic Canada, located in the extreme north-eastern portion of North America, receives acid precipitation from all major acid emission sources on the eastern part of the continent. The region was glaciated and has thin soils over a generally poorly acid buffering bedrock. Because of regional topography, large groupings of lakes occur in a number of regions. Environment Canada and the Government of New Brunswick have operated lake sampling networks in trend detection studies and have concentrated their work on these lake groupings. The MAGIC model has been applied to these lakes and their catchments to see: a what initial water chemistry conditions existed before acidification began, b what the chemistry was like during the worst of regional acid deposition, and c what it would be like under deposition conditions predicted for new Canadian and US emission reduction proposals. While pH, sulphate, acid neutralisation capacity (ANC and the sum of the base cations (SBC of all lakes have been significantly affected by acid deposition, water chemistry conditions are now considerably better than they were in 1975, at the worst of the deposition. However, a 50% reduction in acid deposition from Year 2000 deposition amounts will not return water chemistry to original conditions in most of the region. Keywords: Atlantic Canada, monitoring networks, acidification, predictions, MAGIC

  17. Determining the Central Atlantic Magmatic Province (CAMPS)'s Role in the Increased Flux of CO2 in the end-Triassic Mass Extinction

    Science.gov (United States)

    Srinivasan, P. S.; Bachan, A.; Stanford School of Earth Sciences Department of Paleobiology

    2011-12-01

    The Central Atlantic Magmatic Province (CAMP) is one of the largest flood basalt provinces known. Its empacement coincided with a period of major plant and animal extinctions-the end-Triassic mass extinction. It is postulated that the release of large amounts of carbon dioxide into the atmosphere from the volcanics was one of the causes of this mass extinction. However,the magnitude of impact on ocean chemistry, and timescales involved remain unclear. To determine CAMP's role in this increased flux of CO2, we studied the geochemistry of samples of rock from the Triassic-Jurassic boundary, in northern Italy. Specifically, by observing the ratios of carbon isotopes 12 and 13 in the organic carbon found in these limestone sedimentary rocks, we could determine the ratio of carbonate to organic burial fluxes globally. We drilled limestone rocks from two different sections in the Southern Alps-- Pozzo Glaciale and Val Adrara. Once they were drilled to a fine powder-like form, we acidified the CaCO3 with HCl to isolate the organic carbon. Then, the organic matter was cleaned to rid the acid, and eventually was placed into tin foil to be placed into the Elemental Analyzer, which determined the percent Carbon in each sample. We tested about 200 samples, and placed them into the Mass Spectrometer machine to determine the isotopic ratios of C12 and C13. According to the data, there was a positive excursion for both sample sets, which means that there was an increase in the amount of C13 in the organic matter. The duration of this excursion was at least a few hundred thousand years. This suggests a protracted increase in the burial flux of organic carbon globally, which is consistent with the hypothesized volcanically driven increase in CO2. This further bolsters the contention that CAMP was responsible, in part, for this mass extinction. By studying the earth's recovery from increased carbon fluxes in the past, we can predict the recovery path that our anthropogenically

  18. Recovery of Carbonate Ecosystems Following the End-Triassic Mass Extinction: Insights from Mercury Anomalies and Their Relationship to the Central Atlantic Magmatic Province

    Science.gov (United States)

    Corsetti, F. A.; Thibodeau, A. M.; Ritterbush, K. A.; West, A. J.; Yager, J. A.; Ibarra, Y.; Bottjer, D. J.; Berelson, W.; Bergquist, B. A.

    2015-12-01

    Recent high-resolution age dating demonstrates that the end-Triassic mass extinction overlapped with the eruption of the Central Atlantic Magmatic Province (CAMP), and the release of CO2 and other volatiles to the atmosphere has been implicated in the extinction. Given the potentially massive release of CO2, ocean acidification is commonly considered a factor in the extinction and the collapse of shallow marine carbonate ecosystems. However, the timing of global marine biotic recovery versus the CAMP eruptions is more uncertain. Here, we use Hg concentrations and Hg/TOC ratios as indicators of CAMP volcanism in continental shelf sediments, the primary archive of faunal data. In Triassic-Jurassic strata, Muller Canyon, Nevada, Hg and Hg/TOC levels are low prior to the extinction, rise sharply in the extinction interval, peak just prior to the appearance of the first Jurassic ammonite, and remain above background in association with a depauperate (low diversity) earliest Jurassic fauna. The return of Hg to pre-extinction levels is associated with a significant pelagic and benthic faunal recovery. We conclude that significant biotic recovery did not begin until CAMP eruptions ceased. Furthermore, the initial benthic recovery in the Muller Canyon section involves the expansion of a siliceous sponge-dominated ecosystem across shallow marine environments, a feature now known from other sections around the world (e.g., Peru, Morocco, Austria, etc.). Carbonate dominated benthic ecosystems (heralded by the return of abundant corals and other skeletal carbonates) did not recover for ~1 million years following the last eruption of CAMP, longer than the typical duration considered for ocean acidification events, implying other factors may have played a role in carbonate ecosystem dynamics after the extinction.

  19. Development of passive volcanic margins of the Central Atlantic and initial opening of ocean

    Science.gov (United States)

    Melankholina, E. N.; Sushchevskaya, N. M.

    2015-01-01

    Geological and geophysical data on the Central Atlantic are discussed in order to elucidate the tectonic setting of the initial magmatic activity, rifting, and breakup resulting in the origination of Mesozoic ocean. The structural, magmatic, and historical aspects of the problem are considered. It has been established that the initial dispersed rifting and low-capacity magmatism at proximal margins was followed by the migration of the process toward the central part of region with the formation of distal zones and the development of vigorous magmmatism, further breakup of the lithosphere and ocean opening. Magmatism, its sources, and the features of newly formed magmatic crust at both the rifting and breakup stages of margin development are discussed and compared with subsequent spreading magmatism. Sr, Nd, and Pb isotopic compositions show that the magmatic evolution of the Central Atlantic proximal margins bears the features of two enriched components, one of which is related to the EM-1 source, developing only at the North American margin. Another enriched component typical of the province as a whole is related to the EM-2 source. To a lesser extent, this component is expressed in igneous rocks of Guyana, which also bear the signature of the MORB-type depleted source typical of spreading tholeiites in the Atlantic Ocean. Similar conditions are assumed for subsequent magmatism at the distal margins and for the early spreading basalts in the adjacent Atlantic belt, which also contain a small admixture of enriched material. A comparison of the magmatism at the margins of Central and North Atlantic reveals their specificity distinctly expressed in isotopic compositions of igneous rocks. In contrast to the typical region of the North Atlantic, the immediate melting of the enriched lithospheric source without the participation of plume-related melts is reconstructed for the proximal margins of the Central Atlantic. At the same time, decompression and melting in the

  20. Quantitative Chemical Indices of Weathered Igneous Rocks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A study was conducted to compare the effectiveness of different weathering indices for characterising weathered igneous rocks of Hong Kong. Among eight chemical indices evaluated in this study, the Parker index has been found most suitable for a quantitative description of state of weathering. Based on geochemical results of 174 samples, the index decreases almost linearly with an increasing extent of weathering. The results enable a better understanding of the modification of geotechnical properties of igneous rocks associated with weathering processes.

  1. Inverse methods for modeling non-rigid plate kinematics: Application to mesozoic plate reconstructions of the Central Atlantic

    Science.gov (United States)

    Kneller, Erik A.; Johnson, Christopher A.; Karner, Garry D.; Einhorn, Jesse; Queffelec, Thomas A.

    2012-12-01

    Published plate reconstructions commonly show significant differences in initial plate configuration and syn-extensional opening directions. The variability of published models is primarily due to the difficulty associated with restoring crustal stretching history. Here we present an inverse non-rigid kinematic method that inverts plate motion and present day crustal thickness to approximate the history of bulk lateral strain and crustal thinning associated with lithospheric stretching. The kinematic link between plate motion and bulk crustal thickness that is used with this method is based on insights obtained from geodynamic models. We implement this approach in open source kinematic modeling software and apply it to test new Early Mesozoic plate kinematic models of the Central Atlantic. This application shows that the patterns of stretching inferred from the syn-rift basins of the Newark Supergroup can be explained if (1) syn-rift Euler pole flow lines were parallel to the Grand Banks transform margin and (2) initial formation of the East Coast Margin Igneous Province was coincident with the formation of the Central Atlantic Magmatic Province. These syn-rift to breakup models of the Central Atlantic lead to better constrained models of early seafloor spreading that show full spreading velocities in the ultraslow regime and within the transition from ultraslow to slow spreading regimes.

  2. Sudbury Igneous Complex: Impact melt or igneous rock? Implications for lunar magmatism

    Science.gov (United States)

    Norman, Marc D.

    1992-01-01

    The recent suggestion that the Sudbury Igneous Complex (SIC) is a fractionated impact melt may have profound implications for understanding the lunar crust and the magmatic history of the Moon. A cornerstone of much current thought on the Moon is that the development of the lunar crust can be traced through the lineage of 'pristine' igneous rocks. However, if rocks closely resembling those from layered igneous intrusions can be produced by differentiation of a large impact melt sheet, then much of what is thought to be known about the Moon may be called into question. This paper presents a brief evaluation of the SIC as a differentiated impact melt vs. endogenous igneous magma and possible implications for the magmatic history of the lunar crust.

  3. Shear zone reactivation during South Atlantic rifting in NW Namibia

    Science.gov (United States)

    Koehn, D.; Passchier, C. W.; Salomon, E.

    2013-12-01

    Reactivation of inherited structures during rifting as well as an influence of inherited structures on the orientation of a developing rift has long been discussed (e.g. Piqué & Laville, 1996; Younes & McClay, 2002). Here, we present a qualitative and quantitative study of shear zone reactivation during the South Atlantic opening in NW Namibia. The study area comprises the Neo-Proterozoic rocks of the Kaoko Belt which was formed during the amalgamation of Gondwana. The Kaoko Belt encompasses the prominent ~500 km long ductile Purros shear zone and the Three Palms shear zone, both running sub-parallel to the present continental margin. The Kaoko Belt is partly overlain by the basalts of the Paraná-Etendeka Large Igneous Province, which with an age of ~133 Ma were emplaced just before or during the onset of the Atlantic rifting at this latitude. Combining the analysis of satellite imagery and digital elevation models with extensive field work, we identified numerous faults tracing the old shear zones along which the Etendeka basalts were down-faulted. The faults are often listric, yet we also found evidence for a regional scale basin formation. Our analysis allowed for constructing the geometry of three of these faults and we could thus estimate the vertical offsets to ~150 m, ~500 m, and ~1100 m, respectively. Our results contribute to the view that the basement inheritance plays a significant role on rifting processes and that the reactivation of shear zones can accumulate significant amounts of displacement. References: Pique, A. and E. Laville (1996). The Central Atlantic rifting: Reactivation of Paleozoic structures?. J. Geodynamics, 21, 235-255. Younes, I.A. and K. McClay (2002). Development of accommodation zones in the Gulf of Suez-Red Sea rift, Egypt. AAPG Bulletin, 86, 1003-1026.

  4. Correlating the end-Triassic mass extinction and basalt volcanism of the Central Atlantic Magmatic Province at the 100,000-year level by high-precision U-Pb age determinations

    Science.gov (United States)

    Schoene, Blair; Guex, Jean; Bartolini, Annachiara; Schaltegger, Urs; Blackburn, Terrence J.

    2010-05-01

    The end-Triassic mass extinction is one of the five largest extinctions in Earth history, though considerable uncertainty remains in terms of its duration, causes and effects. Many workers suggest that the extinction was related directly or indirectly to adverse climate following the onset of the Central Atlantic Magmatic Province (CAMP), which erupted > 2.5x106 km3 of basalt in less than 1 Ma. However, there remains a need for precise and accurate geochronology to correlate the onset of CAMP volcanism, recorded uniquely in terrestrial sections, with the well-documented marine extinction event. We provide new chemical abrasion ID-TIMS U-Pb age determinations on ash bed and basaltic zircons using the well-calibrated EARTHTIME 202Pb-205Pb-233U-235U tracer solution, yielding data that are up to 70% more precise compared to single-Pb/single-U tracers. We show that the Triassic-Jurassic boundary (TJB) and end-Triassic biological crisis from two independent marine stratigraphic sections in northern Peru and in Nevada (USA) correlate with the onset of terrestrial flood volcanism in the Central Atlantic Magmatic Province (CAMP) to <150 ka. Ash bed samples reveal complicated U-Pb systematics, showing ranges in 206Pb/238U zircon dates of up to 2 Ma, representing a range of growth histories prior to eruption. Therefore, we use the youngest single closed-system zircon to approximate the eruption date. Three volcanic ash beds from the Pucara basin, northern Peru, bracket the TJB to a 206Pb/238U age of 201.31 ± 0.18/0.31/0.43 Ma (internal uncertainties/ with tracer calibration uncertainty/ with decay constant uncertainties). The first discovered ash bed from the New York canyon, Nevada, 1.5 m above TJB requires a boundary age of less than 201.33 ± 0.13 Ma. We also provide data from two laboratories which yield a new 206Pb/238U zircon age of 201.28 ± 0.02/0.22/0.31 Ma for the North Mtn. basalt, the lowest CAMP basalt from the Fundy basin, Nova Scotia. This narrows the

  5. Evidence for natural molecular hydrogen seepage associated with Carolina bays (surficial, ovoid depressions on the Atlantic Coastal Plain, Province of the USA)

    Science.gov (United States)

    Zgonnik, Viacheslav; Beaumont, Valérie; Deville, Eric; Larin, Nikolay; Pillot, Daniel; Farrell, Kathleen M.

    2015-12-01

    A study of soil gases was made in North Carolina (USA) in and around morphological depressions called "Carolina bays." This type of depression is observed over the Atlantic coastal plains of the USA, but their origin remains debated. Significant concentrations of molecular hydrogen (H2) were detected, notably around the bays. These measurements suggest that Carolina bays are the surficial expression of fluid flow pathways for hydrogen gas moving from depth to the surface. The potential mechanisms of H2 production and transport and the geological controls on the fluid migration pathways are discussed, with reference to the hypothesis that Carolina bays are the result of local collapses caused by the alteration of rock along the deep pathways of H2 migrating towards the surface. The present H2 seepages are comparable to those in similar structures previously observed in the East European craton.

  6. Rb/Sr and U/Pb isotopic ages in basement rocks of Mina Gonzalito and Arroyo Salado, Atlantic North-Patagonian Massif, Rio Negro, Argentina

    International Nuclear Information System (INIS)

    Isotopic ages from metamorphic and plutonic rocks of the Atlantic area of North Patagonian basement indicate that the main crustal tectonic events occurred during the late Proterozoic to early Paleozoic times. Rb/Sr and U/Pb data in the 550-470 Ma interval suggest an old tecto-thermal activity during the upper Brazilian Cycle (Rio Doce Orogeny). At regional scale, the comparable Neo proterozoic basement of Ventania and sedimentary for eland cover of Tandilia continues to the Northeast, in the Dom Feliciano Belt. A possible correlation of the North Patagonian basement with igneous-metamorphic relics of Central Argentina (Pampean Ranges of San Luis-Cordoba and at La Pampa province) is also indicated. (author)

  7. Exposure from an igneous phosphate mine operation

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency Safety Series 115 and European Union Council Directive 96/29/EURATOM have changed the profile of radiation protection completely, increasing the regulatory awareness of natural radiation and the industries involved. Three major industries have been identified in terms of their scope and the materials handled as industries requiring further attention. They are the oil and gas industry, the zircon industry and the phosphate and fertilizer industry. The phosphate and associated fertilizer industry has an added complication, because it has two distinct sources of raw material, i.e. being of igneous or sedimentary origin. The sedimentary material has a dominant 238U series, with activities ranging from 1 Bq/g per isotope to as high as 5.7 Bq/g per isotope, but with negligible 232Th content. The igneous material of the Phalaborwa Complex has fairly low levels of 238U and its associated daughters, (less than 0.15 Bq/g per isotope), but with elevated levels of 232Th when compared with the sedimentary material. This paper will focus on the mining operations of an igneous source located in South Africa. The mine involved received a nuclear authorization in 1993 in terms of the Nuclear Energy Act, No 131 of 1993 and in the following years completed both occupational and public risk assessments as required by the authorization. This paper places emphasis on the public risk assessment completed in 1999 and the results of the subsequent routine monitoring programme, and expands on some of the practical problems the company had to deal with. The public risk assessment was conducted in an integrated manner, assessing doses to members of the public via the atmospheric, aquatic and secondary pathways by the Nuclear Energy Corporation of South Africa and the subsequent routine monitoring programme results evaluated and reported to the regulator by the company itself. Finally, a brief description of the current monitoring programme is given, with

  8. The Central-Western Mediterranean: Anomalous igneous activity in an anomalous collisional tectonic setting

    Science.gov (United States)

    Lustrino, Michele; Duggen, Svend; Rosenberg, Claudio L.

    2011-01-01

    The central-western Mediterranean area is a key region for understanding the complex interaction between igneous activity and tectonics. In this review, the specific geochemical character of several 'subduction-related' Cenozoic igneous provinces are described with a view to identifying the processes responsible for the modifications of their sources. Different petrogenetic models are reviewed in the light of competing geological and geodynamic scenarios proposed in the literature. Plutonic rocks occur almost exclusively in the Eocene-Oligocene Periadriatic Province of the Alps while relatively minor plutonic bodies (mostly Miocene in age) crop out in N Morocco, S Spain and N Algeria. Igneous activity is otherwise confined to lava flows and dykes accompanied by relatively greater volumes of pyroclastic (often ignimbritic) products. Overall, the igneous activity spanned a wide temporal range, from middle Eocene (such as the Periadriatic Province) to the present (as in the Neapolitan of southern Italy). The magmatic products are mostly SiO 2-oversaturated, showing calcalkaline to high-K calcalcaline affinity, except in some areas (as in peninsular Italy) where potassic to ultrapotassic compositions prevail. The ultrapotassic magmas (which include leucitites to leucite-phonolites) are dominantly SiO 2-undersaturated, although rare, SiO 2-saturated (i.e., leucite-free lamproites) appear over much of this region, examples being in the Betics (southeast Spain), the northwest Alps, northeast Corsica (France), Tuscany (northwest Italy), southeast Tyrrhenian Sea (Cornacya Seamount) and possibly in the Tell region (northeast Algeria). Excepted for the Alpine case, subduction-related igneous activity is strictly linked to the formation of the Mediterranean Sea. This Sea, at least in its central and western sectors, is made up of several young (central-western Mediterranean is believed to have tapped mantle 'wedge' regions, metasomatized by pressure-related dehydration of the

  9. Petrología y geoquímica de la unidad ígnea Quebrada Blanca, sierra de la Huerta, Provincia de San Juan Petrology and geochemistry of the Quebrada Blanca Igneous Unit, Sierra de La Huerta, province of San Juan.

    Directory of Open Access Journals (Sweden)

    Brígida Castro de Machuca

    2011-12-01

    Full Text Available La unidad ígnea Quebrada Blanca (Pérmico Superior-Triásico inferior, que intruye al basamento cristalino de la sierra de La Huerta, Sierras Pampeanas Occidentales, es el término más diferenciado de un grupo de rocas ígneas de edad y características similares. Está compuesta por un cuerpo hipabisal de pórfido riolítico, una brecha hidrotermal-intrusiva en la que se distinguen dos facies con marcadas diferencias texturales y composicionales, y diques felsíticos/riolíticos. Esta asociación rocosa define la raíz de una diatrema expuesta por la erosión. La génesis de la brecha estuvo asociada a la cristalización del pórfido riolítico, al brechamiento explosivo y a la exsolución de fluidos magmático-hidrotermales que fracturaron la caperuza solidificada del intrusivo y las rocas metamórficas circundantes, transportando los fragmentos hacia niveles más superficiales. El pórfido se terminó de emplazar con posterioridad, probablemente ocupando el conducto alimentador. Los datos geoquímicos indican para estas litologías contenidos altos en sílice, carácter subalcalino, calcoalcalino de alto K, y afinidad metaluminosa a débilmente peraluminosa. Los contenidos de elementos litófilos de gran radio iónico son altos mientras que los de Sr, P y Ti son bajos. Presentan enriquecimiento en LREE y empobrecimiento en HREE con la relación (La/YbN = 3,37 a 13,67. Las características geoquímicas son compatibles con las de rocas ígneas generadas en arcos volcánicos. Esta unidad es correlacionada tentativamente con la sección superior (dacítica-riolítica del Grupo Choiyoi, y se la asigna a las etapas finales de la evolución del arco magmático continental emplazado a lo largo del borde occidental de Gondwana a partir del Carbonífero superior.The Quebrada Blanca igneous unit (Upper Permian-Lower Triassic intruding the crystalline basement of the Sierra de La Huerta, Western Sierras Pampeanas, is the most differentiated member of a

  10. Introduction to the Apollo collections. Part 1: Lunar igneous rocks

    Science.gov (United States)

    Mcgee, P. E.; Warner, J. L.; Simonds, C. H.

    1977-01-01

    The basic petrographic, chemical, and age data is presented for a representative suite of igneous rocks gathered during the six Apollo missions. Tables are given for 69 samples: 32 igneous rocks and 37 impactites (breccias). A description is given of 26 basalts, four plutonic rocks, and two pyroclastic samples. The textural-mineralogic name assigned each sample is included.

  11. Association of igneous phophate and uranium

    International Nuclear Information System (INIS)

    Data from Catalao permit some brief comments about the association of igneous phosphate and uranium, and on the possible economic importance of this type of mineralization in spite of the low grades of metals observed. Chemical and mineralogical analyses of carbonatites, phosphate ore and different phosphate concentrates, reveal the existence of important low-grade reserves of Th, Nb, Zr, U and La, and possibly of other metals such as V and Cu. Uranium is enriched 1.6 and 1.2 times, respectively, in the residual muds and flotation wastes produced at the processing plant of Goiasfertil operating in the area. The uranium is associated with two types of minerals, the first one comprised primarily of phosphates of the gorceixite group and secondarily of apatite and dahllite. THe second association is with pyrochlore, or rather barium-pyrochlore. Further investigations of similar occurences may define more clearly and specifically the various factors controlling the observed enrichment in heavy elements. (Author)

  12. Number of Waste Package Hit by Igneous Intrusion

    Energy Technology Data Exchange (ETDEWEB)

    M. Wallace

    2004-10-13

    The purpose of this scientific analysis report is to document calculations of the number of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analyses include disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application (TSPA-LA) for the Yucca Mountain Project (YMP). Igneous activity is a disruptive event that is included in the TSPA-LA analyses. Two igneous activity scenarios are considered: (1) The igneous intrusion groundwater release scenario (also called the igneous intrusion scenario) considers the in situ damage to waste packages or failure of waste packages that occurs if they are engulfed or otherwise affected by magma as a result of an igneous intrusion. (2) The volcanic eruption scenario depicts the direct release of radioactive waste due to an intrusion that intersects the repository followed by a volcanic eruption at the surface. An igneous intrusion is defined as the ascent of a basaltic dike or dike system (i.e., a set or swarm of multiple dikes comprising a single intrusive event) to repository level, where it intersects drifts. Magma that does reach the surface from igneous activity is an eruption (or extrusive activity) (Jackson 1997 [DIRS 109119], pp. 224, 333). The objective of this analysis is to develop a probabilistic measure of the number of waste packages that could be affected by each of the two scenarios.

  13. Number of Waste Package Hit by Igneous Intrusion

    International Nuclear Information System (INIS)

    The purpose of this scientific analysis report is to document calculations of the number of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analyses include disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application (TSPA-LA) for the Yucca Mountain Project (YMP). Igneous activity is a disruptive event that is included in the TSPA-LA analyses. Two igneous activity scenarios are considered: (1) The igneous intrusion groundwater release scenario (also called the igneous intrusion scenario) considers the in situ damage to waste packages or failure of waste packages that occurs if they are engulfed or otherwise affected by magma as a result of an igneous intrusion. (2) The volcanic eruption scenario depicts the direct release of radioactive waste due to an intrusion that intersects the repository followed by a volcanic eruption at the surface. An igneous intrusion is defined as the ascent of a basaltic dike or dike system (i.e., a set or swarm of multiple dikes comprising a single intrusive event) to repository level, where it intersects drifts. Magma that does reach the surface from igneous activity is an eruption (or extrusive activity) (Jackson 1997 [DIRS 109119], pp. 224, 333). The objective of this analysis is to develop a probabilistic measure of the number of waste packages that could be affected by each of the two scenarios

  14. Exploring the pre-eruptive history of the Central Atlantic Magmatic Province (CAMP) and the link with the end Triassic extinction using high precision U-Pb zircon and baddeleyite geochronology

    Science.gov (United States)

    Davies, Joshua; Marzoli, Andrea; Bertrand, Hervé; Youbi, Nasrrddine; Schaltegger, Urs

    2015-04-01

    The Central Atlantic Magmatic Province (CAMP) is a massive outpouring of basaltic lava, dykes and sills that was predominantly emplaced into the Triassic-Jurassic basins of North and South America, Europe and Africa. These basins were, at the time, in the center of the paleo-supercontinent Pangea, and the CAMP flood basalts are associated with Pangea's break-up and the opening of the Atlantic Ocean. The global climatic and environmental impact of the basalt eruption has been temporally linked with the end-Triassic mass extinction, although the extinction horizon, defined by a carbon isotope excursion, is stratigraphically below the first basaltic flows in all of the currently identified basins. Therefore, if the extinction is related to the CAMP, it must be related to a process that occurred before the eruption of the first basalt flow, or is co-incident with a currently unidentified older basalt flow. Here we present high precision TIMS zircon U-Pb geochronology on zircons from the North Mountain basalt (NMB) in the Fundy basin, Canada, and also baddeleyite from the Foum Zuid dyke (FZD) in the Anti-Atlas, Morocco. The NMB zircons have been separated from the lowermost accessible basalt flow of the NMB sequence in a coarse-grained section, rather than from a felsic residual melt pod, which is the usual target for zircon geochronology in basalts. The baddeleyites from the FZD were also separated from a coarse-grained section of the dyke. The zircons and baddeleyites from the NMB and FZD samples contain an antecrystic population with ages more than 1 Ma older than the emplacement of the basalts. The U-Pb ages presented here suggest that there was magmatic activity relating to the CAMP before the eruption of the first basalts. There are a number of possible explanations for the old zircons 1) recycling of zircon from earlier phases of magmatism, which then would have to have been re-molten and entrained into the NMB and FZD magmas. 2) Recycling of crystal mush from

  15. A study of radioactive elements of various rocks in Pattani Province with gamma ray spectrometer

    Directory of Open Access Journals (Sweden)

    Kaewtubtim, P.

    2002-01-01

    Full Text Available The radioactivity of the three elements, potassium, uranium and thorium, in rocks of various types in Pattani Province was investigated by using a gamma ray spectrometer. It was found that potassium contents in igneous rocks, sedimentary rocks and metamorphic rocks were 6.29 %, 2.21% and 1.54 % respectively. Uranium equivalent contents in igneous rock, sedimentary rocks and metamorphic rocks were found to be 22.51 ppm, 11.25 ppm and 14.13 ppm, while thorium contents in these rocks were 21.78 ppm, 18.88 ppm and 18.15 ppm respectively. The results obtained were similar to those reported by Pungtip Ranglek (1995 for igneous rock at Liwong Pluton site in Thepha, Na Thawi, Chana and Saba Yoi Districts, Songkhla Province, and were about six times higher than those reported by Kittichai Wattananikorn (1994 for igneous rock in the northern part of Thailand.

  16. Selected references on alkalic igneous rocks of the United States

    Energy Technology Data Exchange (ETDEWEB)

    Hall, C.R. (comp.)

    1976-01-01

    A compilation of references is presented providing background information on rock and mineral associations, geochemistry, geophysics, structural relationships, and geochronology of sialic, feldspathoidal, and some mafic alkalic igneous rock exposures in the US. Their locations and major characteristics are cited. No implication regarding U potential in these areas is intended. The first part of the bibliography provides general references to overall features of alkaline igneous rocks by region. The second part is a compilation of references on alkalic igneous rocks by state or groups of states. The third part provides information on rock type, age, and location for most of the references cited in part two. (JSR)

  17. Drilling through the largest magma chamber on Earth: Bushveld Igneous Complex Drilling Project (BICDP)

    Science.gov (United States)

    Trumbull, R. B.; Ashwal, L. D.; Webb, S. J.; Veksler, I. V.

    2015-05-01

    A scientific drilling project in the Bushveld Igneous Complex in South Africa has been proposed to contribute to the following scientific topics of the International Continental Drilling Program (ICDP): large igneous provinces and mantle plumes, natural resources, volcanic systems and thermal regimes, and deep life. An interdisciplinary team of researchers from eight countries met in Johannesburg to exchange ideas about the scientific objectives and a drilling strategy to achieve them. The workshop identified drilling targets in each of the three main lobes of the Bushveld Complex, which will integrate existing drill cores with new boreholes to establish permanently curated and accessible reference profiles of the Bushveld Complex. Coordinated studies of this material will address fundamental questions related to the origin and evolution of parental Bushveld magma(s), the magma chamber processes that caused layering and ore formation, and the role of crust vs. mantle in the genesis of Bushveld granites and felsic volcanic units. Other objectives are to study geophysical and geodynamic aspects of the Bushveld intrusion, including crustal stresses and thermal gradient, and to determine the nature of deep groundwater systems and the biology of subsurface microbial communities.

  18. The age, geology, and geochemistry of the Tapuaenuku Igneous Complex, Marlborough, New Zealand

    International Nuclear Information System (INIS)

    The Tapuaenuku Igneous Complex (TIC) is a mid-Cretaceous layered intrusion and dike swarm cropping out at the axis of the Inland Kaikoura Ranges, South Island, New Zealand. The TIC is part of an extensive, but poorly preserved, igneous province that formed during pr after cessation of subduction along the margin of Gondwana c. 100 Ma ago. The TIC is a complex, multiphase intrusion that is subdivided into eight unites (in order of relative emplacement): (1) radial dike swarm - basanite, trachybasalt, and shoshonite/latite dikes; (2) Layered Series (LS) - basin-shaped mafic cumulate rocks; (3) Staircase Intrusives - noncumulate gabbro and monzogabbro enclosed by a discontinuous sheet of cumulate gabbro; (4) Lower Hodder Gabbro and minor gabbroic intrusives - small sticks of noncumulate gabbro, mozogabbro, and monzonite; (5) Red Hills Breccia Pipe - heterolithic breccia emplaced in a pipe or diatreme; (6) Hodder Intrusives - a monzonite and sodalite syenite laccolith intruding the LS; (7)monzonite, orthoclase syenite and quartz syenite sills and dikes, and: (8) highly alkaline lamprophyre, phonotephrite, tephriphonolite, and phonolite dikes. The plethora of rock types in the TIC were produced by fractionation of different mineral assemblages from a trachybasalt or basanite parent magma. The parental magma had incompatible trace element and radiogenic isotopic characteristics similar to HIMU-type ocean island basalt and akin to that of the numerous Cenozoic intraplate volcanic provinces situated in southern New Zealand. However, elevated initial Sr isotope rations of some of the intrusive unites require them to have assimilated Torlesse greywacke country rock. (authors). 52 refs., 9 figs., 8 tabs

  19. Igneous-sedimentary petroleum systems; Sistemas petroliferos igneo-sedimentares

    Energy Technology Data Exchange (ETDEWEB)

    Eiras, Jaime Fernandes [Para Univ., Belem, PA (Brazil)]. E-mail: eiras@ufpa.br; Wanderley Filho, Joaquim Ribeiro [PETROBRAS S.A., Manaus, AM (Brazil). Unidade de Negocios-BSOL]. E-mail: jwand@petrobras.com.br

    2003-07-01

    Igneous-sedimentary petroleum systems are mixed systems in which one or more essential elements or processes are related to magmatic events. Many examples worldwide are presented to show the importance of igneous rocks in the exploratory activities, as well as in the petroleum occurrence. Volcanic ash layers are of great importance in stratigraphic correlation and elucidation of structures, particularly when they occur in thick nonfossiliferous strata. They are also good indicators of turbidite deposition where turbidity currents are related to earthquakes generated by magmatic events. Unconventional reservoirs can be created by volcanic eruptions or intrusions, crystallization, reworking, and fracturing. Unaltered igneous rocks can seal vertically and laterally conventional reservoirs due to its excellent cap capacity. Abnormal thermal effect of igneous rocks can compensate the lack of overburden in shallow basins. Structural or combined traps can be formed due to intrusions, such as folded, faulted, and unconformity traps. Porosity can be either primary or secondary, or both. Primary porosity mainly consists of cavities produced by gas volatilization during eruption and cooling. Secondary porosity refers to those pores that result from hydrothermal alteration, recrystallization, and dissolution by groundwater, and tectonic stress. It includes intercrystalline pores formed by crystallization of various secondary minerals, dissolution pores, and tectonic fractures. New technologies of petroleum development and production are encouraging to search for oil and gas within igneous rocks, and new discoveries are expected. (author)

  20. Magma Emplacement and the 3D Geometry of Igneous Bodies in Rift Basins: Insights from the Bornu Basin, Onshore NE Nigeria

    Science.gov (United States)

    Suleiman, Adamu; Jackson, Christopher; Magee, Craig; Fraser, Alastair

    2016-04-01

    Recent studies of regional unconformities in the circum-South Atlantic tectonic plates have linked unconformity age to the timing of changes in the azimuth of oceanic fracture zones, caused by plate interactions during opening of the South Atlantic. This observation is significant, proposing that a plate boundary geodynamic processes are transmitted into and expressed in plate interiors. However, it is not yet clear if and how other geologic events, such as intra-plate magmatism, may be linked to changes in the oceanic fracture azimuthal geometry. Here we use 2D and 3D seismic reflection, geochemical, borehole datasets and outcrop observations from the Bornu Basin, one of several intra-continental rift basins located in NE Nigeria to constrain the 3D geometry of igneous bodies and magmatic emplacement processes. This allows us to link South Atlantic plate boundary geodynamics and magmatism in the surrounding continental rift basins. Seismic attributes, reflection intensity, relative acoustic impedance, were used to identify and map igneous intrusions. Saucer-shaped sills are the most common type of intrusion, although en-echelon sills, up to 1.4 km in length, were also identified. The 3D geometry of the sills reveals the detailed structural components like inner sill, inclined sheets and outer sill. A mapped bifurcating network of the sills suggests magma emplacement process through upward and outward propagation. Seismic-stratigraphic observations indicate that igneous activity occurred in the Early Cretaceous, Late Cretaceous and Paleogene corresponding to the timing of major azimuth changes observed in the Kane Oceanic fracture zone in the South Atlantic Ocean. Overall, our study, suggests a possible influence of plate boundary geodynamics on intra-plate magmatism as reflected in the link between the time of changes in the azimuth of oceanic fracture zones and magmatic emplacement observed in the tectono-stratigraphy of the intra-continental rift basins.

  1. Investigation of igneous rocks in Huanghua depression, North China, from magnetic derivative methods

    International Nuclear Information System (INIS)

    The igneous rock study plays an important role in understanding the tectonic evolution of sedimentary basins. The distribution of igneous rocks is one of the basic aspects in the igneous rock study. Based on the magnetic susceptibility contrast of igneous and other rocks, magnetic methods are usually used in the igneous rock investigation. In this paper, we delineated the distribution of igneous rocks in Huanghua depression based on the reduction to pole (RTP) magnetic anomaly and its derivative processing results. The main methods used to enhance the anomaly character of igneous rocks include total horizontal derivative, analytic signal modules and the tilt angle. Based on the RTP anomaly and the derivative results, three types of igneous rock distribution areas are predicted in Huanghua depression. The large scale igneous rocks are mainly distributed in the north part of Huanghua depression. The string bead-shaped igneous rocks are mainly located in the north and southwest parts. Some craters are located in the middle-south part. The distribution of igneous rocks is controlled by the deep buried fault along the coastal boundary and the associated tertiary faults. Our study verified the validity of the magnetic derivative methods for the planar distribution study of igneous rocks. The study results of Huanghua depression are the basis of the seismic interpretation of igneous rocks and the tectonic study in this area

  2. Atlantic reef fish biogeography and evolution

    Science.gov (United States)

    Floeter, S.R.; Rocha, L.A.; Robertson, D.R.; Joyeux, J.C.; Smith-Vaniz, W.F.; Wirtz, P.; Edwards, A.J.; Barreiros, J.P.; Ferreira, C.E.L.; Gasparini, J.L.; Brito, A.; Falcon, J.M.; Bowen, B.W.; Bernardi, G.

    2008-01-01

    Aim: To understand why and when areas of endemism (provinces) of the tropical Atlantic Ocean were formed, how they relate to each other, and what processes have contributed to faunal enrichment. Location: Atlantic Ocean. Methods: The distributions of 2605 species of reef fishes were compiled for 25 areas of the Atlantic and southern Africa. Maximum-parsimony and distance analyses were employed to investigate biogeographical relationships among those areas. A collection of 26 phylogenies of various Atlantic reef fish taxa was used to assess patterns of origin and diversification relative to evolutionary scenarios based on spatio-temporal sequences of species splitting produced by geological and palaeoceanographic events. We present data on faunal (species and genera) richness, endemism patterns, diversity buildup (i.e. speciation processes), and evaluate the operation of the main biogeographical barriers and/or filters. Results: Phylogenetic (proportion of sister species) and distributional (number of shared species) patterns are generally concordant with recognized biogeographical provinces in the Atlantic. The highly uneven distribution of species in certain genera appears to be related to their origin, with highest species richness in areas with the greatest phylogenetic depth. Diversity buildup in Atlantic reef fishes involved (1) diversification within each province, (2) isolation as a result of biogeographical barriers, and (3) stochastic accretion by means of dispersal between provinces. The timing of divergence events is not concordant among taxonomic groups. The three soft (non-terrestrial) inter-regional barriers (mid-Atlantic, Amazon, and Benguela) clearly act as 'filters' by restricting dispersal but at the same time allowing occasional crossings that apparently lead to the establishment of new populations and species. Fluctuations in the effectiveness of the filters, combined with ecological differences among provinces, apparently provide a mechanism

  3. Disruptive event analysis: volcanism and igneous intrusion

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.M.

    1980-08-01

    An evaluation is made of the disruptive effects of volcanic activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by volcanic activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future volcanic activity. And third, can the probability of repository disruption by volcanic activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by volcanic activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of volcanism. Potential radionuclide dispersal by volcanic transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or volcanic provinces within the western United States have been sites of significant volcanism and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active volcanism are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of volcanic activity and a numerical evaluation of the areal extent of volcanic disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past volcanic activity.

  4. Disruptive event analysis: volcanism and igneous intrusion

    International Nuclear Information System (INIS)

    An evaluation is made of the disruptive effects of volcanic activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by volcanic activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future volcanic activity. And third, can the probability of repository disruption by volcanic activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by volcanic activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of volcanism. Potential radionuclide dispersal by volcanic transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or volcanic provinces within the western United States have been sites of significant volcanism and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active volcanism are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of volcanic activity and a numerical evaluation of the areal extent of volcanic disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past volcanic activity

  5. Large Silica-Rich Igneous-Textured Inclusions in the Buzzard Coulee (H4) Chondrite

    Science.gov (United States)

    Ruzicka, A.; Hutson, M.; Floss, C.; Hildebrand, A.

    2012-03-01

    Buzzard Coulee (H4) contains two types of large, igneous inclusions that are best explained by igneous differentiation, but which also show evidence for cooling and vapor phase phenomena consistent with transit through a space environment.

  6. Petrology and geochemistry of igneous inclusions in recent Merapi deposits

    DEFF Research Database (Denmark)

    Chadwick, J.P.; Troll, V.R.; Waight, Tod Earle;

    2013-01-01

    Recent basaltic-andesite lavas from Merapi volcano contain abundant and varied igneous inclusions suggesting a complex sub-volcanic magmatic system for Merapi volcano. In order to better understand the processes occurring beneath Merapi, we have studied this suite of inclusions by petrography, ge...

  7. Analysis on structure of igneous formation with fractal dimension of logs

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Reflecting the structure of igneous formation by calculating fractal dimension of logs, the fractal dimension of pyroclastic is larger than lava. Structure of pyroclastic is more complicated than that of lava, so reflecting the structure of igneous formation's complexity with fractal dimension is feasible. It is feasible to refleet the structure of igneous formation's complexity with fractal dimension.

  8. Geometries of doleritic intrusions in central Spitsbergen, Svalbard: an integrated study of an onshore-offshore magmatic province with implications for CO2 sequestration

    OpenAIRE

    Senger, Kim; Roy, Srikumar; Braathen, Alvar; Buckley, Simon John; Bælum, Karoline; Gernigon, Laurent; Mjelde, Rolf; Noormets, Riko; Ogata, Kei; Olaussen, Snorre; Planke, Sverre; Ruud, Bent Ole; Tveranger, Jan

    2013-01-01

    Igneous intrusions emplaced during the Early Cretaceous are well exposed in central Spitsbergen within the Permian–Jurassic sedimentary succession. The doleritic intrusions are collectively classified as the Diabasodden Suite, and form part of the High Arctic Large Igneous Province. Though relatively easily accessible and very well exposed in places, the Diabasodden Suite dolerites remain underexplored and their prevalent geometry is particularly poorly understood. In this contribution ...

  9. Martian Igneous Geochemistry: The Nature of the Martian Mantle

    Science.gov (United States)

    Mittlefehldt, D. W.; Elkins-Tanton, L. T.; Peng, Z. X.; Herrin, J. S.

    2012-01-01

    Mafic igneous rocks probe the interiors of their parent objects, reflecting the compositions and mineralogies of their source regions, and the magmatic processes that engendered them. Incompatible trace element contents of mafic igneous rocks are widely used to constrain the petrologic evolution of planets. We focus on incompatible element ratios of martian meteorites to constrain the petrologic evolution of Mars in the context of magma ocean/cumulate overturn models [1]. Most martian meteorites contain some cumulus grains, but regardless, their incompatible element ratios are close to those of their parent magmas. Martian meteorites form two main petrologic/ age groupings; a 1.3 Ga group composed of clinopyroxenites (nakhlites) and dunites (chassignites), and a <1 Ga group composed of basalts and lherzolites (shergottites).

  10. Why igneous wollastonite is so rare in CAIs

    OpenAIRE

    Beckett, J. R.; Thrane, K.; Krot, A. N.

    2008-01-01

    Primary wollastonite (wo) thought to have crystallized from a liquid is quite rare in CAIs, having been reported in only two igneous inclusions, White Angel and KT-1 [1, 2]. Both of these CAIs exhibit significant mass fractionations in multiple elements and KT-1 is a FUN inclusion, so it is highly desirable to place as many constraints as possible on their formation. Since phase diagrams previously developed for CAIs do not involve wo [3], we use literature data on wo-satura...

  11. Potential Future Igneous Activity at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Location, timing, and volumes of post-Miocene volcanic activity, along with expert judgment, provide the basis for assessing the probability of future volcanism intersecting a proposed repository for nuclear waste at Yucca Mountain, Nevada. Analog studies of eruptive centers in the region that may represent the style and extent of possible future igneous activity at Yucca Mountain have aided in defining the consequence scenarios for intrusion into and eruption through a proposed repository. Modeling of magmatic processes related to magma/proposed repository interactions has been used to assess the potential consequences of a future igneous event through a proposed repository at Yucca Mountain. Results of work to date indicate future igneous activity in the Yucca Mountain region has a very low probability of intersecting the proposed repository. Probability of a future event intersecting a proposed repository at Yucca Mountain is approximately 1.7 x 10-8 per year. Since completion of the Probabilistic Volcanic Hazard Assessment (PVHA) in 1996, anomalies representing potential buried volcanic centers have been identified from aeromagnetic surveys. A re-assessment of the hazard is currently underway to evaluate the probability of intersection in light of new information and to estimate the probability of one or more volcanic conduits located in the proposed repository along a dike that intersects the proposed repository. US Nuclear Regulatory Commission regulations for siting and licensing a proposed repository require that the consequences of a disruptive event (igneous event) with annual probability greater than 1 x 10-8 be evaluated. Two consequence scenarios are considered: (1) igneous intrusion-poundwater transport case and (2) volcanic eruptive case. These scenarios equate to a dike or dike swarm intersecting repository drifts containing waste packages, formation of a conduit leading to a volcanic eruption through the repository that carries the contents of the

  12. Igneous and tectonic evolution of Venusian and terrestrial coronae

    Science.gov (United States)

    Kargel, J. S.; Komatsu, G.

    1992-01-01

    A great variety of tectonic and volcanic features have been documented on Venus. It is widely appreciated that there are close spatial associations among certain types of tectonic structures and some classes of volcanic flows and constructs. Coronae are endowed with a particularly rich variety of volcanism. It is thought that coupled tectonic and volcanic aspects of coronae are cogenetic manifestations of mantle plumes. An outstanding feature of most venusian coronae is their circular or elliptical shape defined by peripheral zones of fracturing and/or folding. Some coronae are composite, consisting of two or more small coronae within a larger enclosing corona, suggesting complex histories of structured diapirism analogous in some ways to salt dome tectonics. Coronae range widely in size, from smaller than 100 km to over 1000 km in diameter. Volcanic features associated with venusian coronae include lunar-like sinuous rilles, thin lava flows, cinder cone-like constructs, shield volcanos, and pancake domes. Several types of volcanic features are often situated within or near a single corona, in many instances including land-forms indicating effusions of both low- and high-viscosity lavas. In some cases stratigraphic evidence brackets emplacement of pancake domes during the period of tectonic development of the corona, thus supporting a close link between the igneous and tectonic histories of coronae. These associations suggest emplacement of huge diapirs and massive magmatic intrusions, thus producing the tectonic deformations defining these structures. Igneous differentiation of the intrusion could yield a range of lava compositions. Head and Wilson suggested a mechanism that would cause development of neutral buoyancy zones in the shallow subsurface of Venus, thereby tending to promote development of massive igneous intrusions.

  13. Public exposure from mines operating on an igneous orebody

    International Nuclear Information System (INIS)

    The impact on members of the public from the extraction and beneficiation of naturally occurring radioactive materials is of primary concern for responsible operators. In Phalaborwa, South Africa, two companies mine and beneficiate an igneous orebody in close proximity to the community. The unique features of this community allow an integrated look into the radiological impact of these activities. It is shown that the doses received by members of the public in the surrounding community are far below the public dose limit and similar to or less than the statistical variation in natural background. (author)

  14. Volcanism and igneous processes in small icy satellites

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, D.J. (California Inst. of Tech., Pasadena (USA). Div. of Geological and Planetary Sciences)

    1982-07-08

    It is argued that the most likely cause of endogenic processes in the small saturnian satellites is the igneous activity associated with a low melting point NH/sub 3/-H/sub 2/O magma. Radiogenic heating probably suffices to provide the necessary melting in Tethys, Dione, Rhea and Iapetus whereas tidal heating is needed for Enceladus and possibly Mimas. Migration of large fluid-filled cracks, leading to surface flooding, is likely. If clathrates are present, then pyroclast-forming explosive events can occur at a near-surface intrusive contact between magma and one or more of the methane, nitrogen and argon clathrates.

  15. Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

    Science.gov (United States)

    Bouse, R.M.; Ruiz, J.; Titley, S.R.; Tosdal, R.M.; Wooden, J.L.

    1999-01-01

    Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206Pb/204Pb = 17.34 to 22.66, 207Pb/204Pb = 15.43 to 15.96, and 208Pb/204Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206Pb/204Pb and higher model Th/U, and the southern subprovince has higher 206Pb/204Pb and

  16. Genetic Connectivity between North and South Mid-Atlantic Ridge Chemosynthetic Bivalves and Their Symbionts

    OpenAIRE

    van der Heijden, Karina; Petersen, Jillian M.; Dubilier, Nicole; Borowski, Christian

    2012-01-01

    Transform faults are geological structures that interrupt the continuity of mid-ocean ridges and can act as dispersal barriers for hydrothermal vent organisms. In the equatorial Atlantic Ocean, it has been hypothesized that long transform faults impede gene flow between the northern and the southern Mid-Atlantic Ridge (MAR) and disconnect a northern from a southern biogeographic province. To test if there is a barrier effect in the equatorial Atlantic, we examined phylogenetic relationships o...

  17. Subsurface Structure of the Bushveld Igneous Complex, South Africa: An Application of Geophysics

    Science.gov (United States)

    Vallejo, G.; Galindo, B. L.; Carranza, V.; Gomez, C. D.; Ortiz, K.; Castro, J. G.; Falzone, C.; Guandique, J.; Emry, E.; Webb, S. J.; Nyblade, A.

    2014-12-01

    South Africa is host to the largest single known platinum group metal supply in the world. The Bushveld Igneous Complex, spanning 300x400 kilometers, hosts hundreds of years' worth of platinum, chromite, vanadium, and other ore. Its wealth of these metals is tied directly to the large layered igneous intrusion that formed roughly 2061 million years ago. The extraction of platinum is vital to the industrial world - as these metals are widely used in the automotive industry, dental restorations, computer technology, in addition to many other applications. In collaboration with the Africa Array geophysics field school and the Penn State Summer Research Opportunities Program (SROP), we surveyed the Modikwa mine located along the border of the provinces of Mpumalanga and Limpopo in South Africa. The following techniques were applied to survey the area of interest: seismic refraction and reflection, gravity, magnetics, electrical resistivity, and electromagnetics. The data collected were used to determine the depth to bedrock and to identify potential mining hazards from dykes and faults in the bedrock. Several areas were studied and with the combination of the above-mentioned methods several possible hazards were identified. One broad, major dyke that was located in a prior aeromagnetic survey and several previously undetected, parallel, minor dykes were identified in the region. The overburden thickness was determined to be ̴4-5 meters in some regions, and as thin as several centimeters in others. This section of rock and soil lies above an area where platinum will likely be mined in the future. The removal of overburden can be accomplished by using power shovels or scrapers; while remaining material can be contained with the use of galvanized steel culverts. Additionally, a number of joints were located that may have allowed water to accumulate underground. The models created from the data permit us to estimate which hazards could be present in different parts of the

  18. A new starting point for the South and Equatorial Atlantic Ocean

    OpenAIRE

    Moulin, Maryline; Aslanian, Daniel; Unternehr, Patrick

    2010-01-01

    The opening of the Equatorial and South Atlantic Oceans is still a matter of debate, particularly as concerns the locations of the intraplate deformation. We propose here a critical review of the kinematic models published since Bullard et al., 1965, based on a series of constraints: new interpretation of the magnetic anomalies, seafloor isochrons, flow lines, fracture zones, continental and oceanic homologous structures and radiometric dating of igneous rocks. All of these models present num...

  19. SHRIMP zircon U-Pb geochronology of early Mesozoic felsic igneous rocks from the southern Lancangjiang and its tectonic implications

    Institute of Scientific and Technical Information of China (English)

    PENG Touping; WANG Yuejun; FAN Weiming; LIU Dunyi; SHI Yuruo; MIAO Laicheng

    2006-01-01

    The SHRIMP zircon U-Pb geochronology of three typical samples, including two monzonitic granites from the Lincang batholith and a rhyolite from the Manghuai Formation are presented in the southern Lancangjiang, western Yunnan Province. The analyses of zircons for the biotite monzonitic granites from the northern (02DX-137) and southern (20JH-10) Lincang batholith show the single and tight clusters on the concordia, and yield the weighted mean 206pb/238U ages of 229.4 ± 3.0 Ma and 230.4 ± 3.6 Ma, respectively, representing the crystallized ages of these granites. The zircons for the rhyolitic sample (02DX-95) from the Manghuai Formation give a weighted mean 206Pb/238U age of 231.0 ± 5.0 Ma. These data suggest that the igneous rocks from the Lincang granitic batholith and Manghuai Formation have a similar crystallized age. In combination with other data, it is inferred that both were generated at a narrow age span (~230 Ma) and were originated from the postcollisional tectonic regime. An early Proterozoic 206Pb/238U apparent age of 1977±44 Ma is additionally obtained from one zircon from the biotite monzonitic granite (southern Lincang batholith), indicative of development of the early Proterozoic Yangtze basement in the region. These precisely geochronological data provide important constraints on better understanding the Paleozoic tectonic evolution of the Tethys, western Yunnan Province.

  20. The key role of mica during igneous concentration of tantalum

    Science.gov (United States)

    Stepanov, Aleksandr; A. Mavrogenes, John; Meffre, Sebastien; Davidson, Paul

    2014-06-01

    Igneous rocks with high Ta concentrations share a number of similarities such as high Ta/Nb, low Ti, LREE and Zr concentrations and granitic compositions. These features can be traced through fractionated granitic series. Formation of Ta-rich melts begins with anatexis in the presence of residual biotite, followed by magmatic crystallization of biotite and muscovite. Crystallization of biotite and muscovite increases Ta/Nb and reduces the Ti content of the melt. Titanium-bearing oxides such as rutile and titanite are enriched in Ta and have the potential to deplete Ta at early stages of fractionation. However, mica crystallization suppresses their saturation and allows Ta to increase in the melt. Saturation with respect to Ta and Nb minerals occurs at the latest stages of magmatic crystallization, and columbite can originate from recrystallization of mica. We propose a model for prediction of intrusion fertility for Ta.

  1. Natural radioactivity and radon exhalation rate in Brazilian igneous rocks

    Energy Technology Data Exchange (ETDEWEB)

    Moura, C.L.; Artur, A.C. [Departamento de Petrologia e Metalogenia, Instituto de Geociencias e Ciencias Exatas, Universidade Estadual Paulista (UNESP), Av. 24-A No. 1515, C.P. 178, CEP 13506-900, Rio Claro, Sao Paulo (Brazil); Bonotto, D.M., E-mail: danielbonotto@yahoo.com.b [Departamento de Petrologia e Metalogenia, Instituto de Geociencias e Ciencias Exatas, Universidade Estadual Paulista (UNESP), Av. 24-A No. 1515, C.P. 178, CEP 13506-900, Rio Claro, Sao Paulo (Brazil); Guedes, S. [Departamento de Cronologia e Raios Cosmicos, Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas (UNICAMP), Rua Sergio Buarque de Holanda No. 777, CEP 13083-859, Campinas, Sao Paulo (Brazil); Martinelli, C.D. [Departamento de Petrologia e Metalogenia, Instituto de Geociencias e Ciencias Exatas, Universidade Estadual Paulista (UNESP), Av. 24-A No. 1515, C.P. 178, CEP 13506-900, Rio Claro, Sao Paulo (Brazil)

    2011-07-15

    This paper reports the natural radioactivity of Brazilian igneous rocks that are used as dimension stones, following the trend of other studies on the evaluation of the risks to the human health caused by the rocks radioactivity as a consequence of their use as cover indoors. Gamma-ray spectrometry has been utilized to determine the {sup 40}K, {sup 226}Ra and {sup 232}Th activity concentrations in 14 rock types collected at different quarries. The following activity concentration range was found: 12.18-251.90 Bq/kg for {sup 226}Ra, 9.55-347.47 Bq/kg for {sup 232}Th and 407.5-1615.0 Bq/kg for {sup 40}K. Such data were used to estimate Ra{sub eq}, H{sub ex} and I{sub {gamma}}, which were compared with the threshold limit values recommended in literature. They have been exceeded for Ra{sub eq} and H{sub ex} in five samples, where the highest indices corresponded to a rock that suffered a process of ductile-brittle deformation that caused it a microbrecciated shape. The exhalation rate of Rn and daughters has also been determined in slabs consisting of rock pieces {approx}10 cm-long, 5 cm-wide and 3 cm-thick. It ranged from 0.24 to 3.93 Bq/m{sup 2}/h and exhibited significant correlation with eU (={sup 226}Ra), as expected. The results indicated that most of the studied rocks did not present risk to human health and may be used indoors, even with low ventilation. On the other hand, igneous rocks that yielded indices above the threshold limit values recommended in literature may be used outdoors without any restriction or indoors with ample ventilation.

  2. Geomorphological mapping of granite zones in the province of Girona (Catalunya, Spain)

    OpenAIRE

    Roqué i Pau, Carles; Pallí i Buxó, Lluís; Brusi i Belmonte, David

    1997-01-01

    Since 1978, the unity of Geodynamics of the University of Girona has been publishing a series of detailed geological and geomorphological maps of different municipal terms of the Province of Girona, mainly on the scale of 1:10.000, situated for the major part in the Littoral and Prelittoral mountain ranges of the Cadena Costera Catalana. These mountain ranges are constituted of materials belonging to the palaeozoic era, basically metamorphous and igneous rocks (plutomc and hypoabyssal rocks)

  3. Petrology and geochemistray of Imam-Zadeh Hashem mafic and ultramafic bodies, southern Guilan province

    OpenAIRE

    Mojgan Salavati; Reza Fahim Guilani

    2013-01-01

    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 setti...

  4. Characterizing silicic rocks in the Parana Magmatic Province: an update in their origin and emplacement

    Science.gov (United States)

    Luchetti, A. F.; Nardy, A. R.; Machado, F. B.; Gravley, D. M.; Gualda, G. A.

    2013-12-01

    The Paraná Magmatic Province (PMP), a large igneous province in southern Brazil (with correlative rocks in western Africa), includes 800,000 km3 of flood basalts generated during the rifting that ultimately led to the opening of the South Atlantic and covers nearly 75% of the surface of the Paraná Basin. Towards the top of the volcanic pile, silicic rocks are observed in many areas. They comprise a small proportion of the total erupted volume (2.5%), yet correspond to a significant flare-up of silicic volcanism over a period of only a few million years. In Brazil, the silicic rocks are divided into two groups, the Chapecó Member, which appears more northerly and includes porphyritic, crystal-rich, high-Ti dacites and trachydacites; and the Palmas Member, which includes fine-grained, crystal-poor, low-Ti dacites and rhyolites. The mode of emplacement (lavas vs. pyroclastic flows) of the volcanic units has been the subject of much controversy. The aim of this project is to better understand the origin and evolution of the PMP silicic rocks. We are combining information from the regional to the thin section scale to better characterize eruption dynamics and magma distribution prior to eruption. In both Palmas and Chapecó units, we observe features consistent with emplacement in the form of pyroclastic density currents, e.g. fiamme, variable weathering patterns consistent with local variations in welding at the outcrop scale, vertical gas-escape structures, sedimentary dykes, and lythophysae. Some ignimbrite units can be traced for 10's of kilometers and with more research on their spatial distribution could reveal the location of eruptive centers. In the Palmas, ignimbrites can be observed juxtaposed against or overlying discrete eruptive centers in the form of discordant structures that resemble domes and coulees typical of lava extrusion and flow. However, many of the silicic rocks are ambiguous and difficult to characterize, with features that could be related

  5. South Atlantic Shrimp System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SEFSC, in cooperation with the South Atlantic states, collects South Atlantic shrimp data from dealers and fishermen. These data are collected to provide catch,...

  6. 2005 Atlantic Hurricanes Poster

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 2005 Atlantic Hurricanes poster features high quality satellite images of 15 hurricanes which formed in the Atlantic Basin (includes Gulf of Mexico and...

  7. Abstracts of the Atlantic Geoscience Society's 2007 colloquium and annual general meeting

    International Nuclear Information System (INIS)

    The Atlantic Geoscience Society (AGS) hosts annual meetings, workshops and field trips to promote a better understanding of the geology of Atlantic Canada. This colloquium highlighted current research in the Atlantic provinces with special sessions devoted to patterns and geohazards in the North Atlantic; late and post-glacial climate change events in eastern Canada; salt matters; tectonic, thermal and resource aspects of Paleozoic to Mesozoic evaporite basins; mineral resources research by students of the Society of Economic Geologists; dendrochronology; a physical volcanology workshop; and, a North American soil geochemical landscape project orientation session. One of the 74 papers presented at this colloquium has been catalogued separately for inclusion in this database

  8. Complete Analytical Data for Samples of Jurassic Igneous Rocks in the Bald Mountain Mining District, Nevada

    Science.gov (United States)

    du Bray, Edward A.

    2009-01-01

    This report presents all petrographic, major oxide, and trace element data for a set of 109 samples collected during an investigation of Jurassic igneous rocks in the Bald Mountain mining district, Nevada. Igneous rocks in the district include the Bald Mountain stock, quartz-feldspar porphyry dikes, basaltic andesite dikes, aplite sills, and rare lamprophyre dikes. These rocks, although variably altered near intrusion-related mineral deposits, are fresh in many parts of the district. Igneous rocks in the district are hosted by Paleozoic sedimentary rocks.

  9. Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    F. Perry; B. Youngs

    2000-11-06

    The purpose of this Analysis/Model (AMR) report is twofold. (1) The first is to present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the Probabilistic Volcanic Hazard Analysis (PVHA) (CRWMS M&O 1996). Conceptual models presented in the PVHA are summarized and extended in areas in which new information has been presented. Alternative conceptual models are discussed as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) The second purpose of the AMR is to present probability calculations based on PVHA outputs. Probability distributions are presented for the length and orientation of volcanic dikes within the repository footprint and for the number of eruptive centers located within the repository footprint (conditional on the dike intersecting the repository). The probability of intersection of a basaltic dike within the repository footprint was calculated in the AMR ''Characterize Framework for Igneous Activity at Yucca Mountain, Nevada'' (CRWMS M&O 2000g) based on the repository footprint known as the Enhanced Design Alternative [EDA II, Design B (CRWMS M&O 1999a; Wilkins and Heath 1999)]. Then, the ''Site Recommendation Design Baseline'' (CRWMS M&O 2000a) initiated a change in the repository design, which is described in the ''Site Recommendation Subsurface Layout'' (CRWMS M&O 2000b). Consequently, the probability of intersection of a basaltic dike within the repository footprint has also been calculated for the current repository footprint, which is called the 70,000 Metric Tons of Uranium (MTU) No-Backfill Layout (CRWMS M&O 2000b). The calculations for both

  10. Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    The purpose of this Analysis/Model (AMR) report is twofold. (1) The first is to present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the Probabilistic Volcanic Hazard Analysis (PVHA) (CRWMS M and O 1996). Conceptual models presented in the PVHA are summarized and extended in areas in which new information has been presented. Alternative conceptual models are discussed as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) The second purpose of the AMR is to present probability calculations based on PVHA outputs. Probability distributions are presented for the length and orientation of volcanic dikes within the repository footprint and for the number of eruptive centers located within the repository footprint (conditional on the dike intersecting the repository). The probability of intersection of a basaltic dike within the repository footprint was calculated in the AMR ''Characterize Framework for Igneous Activity at Yucca Mountain, Nevada'' (CRWMS M and O 2000g) based on the repository footprint known as the Enhanced Design Alternative [EDA II, Design B (CRWMS M and O 1999a; Wilkins and Heath 1999)]. Then, the ''Site Recommendation Design Baseline'' (CRWMS M and O 2000a) initiated a change in the repository design, which is described in the ''Site Recommendation Subsurface Layout'' (CRWMS M and O 2000b). Consequently, the probability of intersection of a basaltic dike within the repository footprint has also been calculated for the current repository footprint, which is called the 70,000 Metric Tons of Uranium (MTU) No-Backfill Layout (CRWMS M and O 2000b). The calculations for both footprints are presented in this AMR. In

  11. Supervolcanoes within an ancient volcanic province in Arabia Terra, Mars.

    Science.gov (United States)

    Michalski, Joseph R; Bleacher, Jacob E

    2013-10-01

    Several irregularly shaped craters located within Arabia Terra, Mars, represent a new type of highland volcanic construct and together constitute a previously unrecognized Martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae possess a range of geomorphic features related to structural collapse, effusive volcanism and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulphur and erupted fine-grained pyroclastics from these calderas probably fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. The discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars. PMID:24091975

  12. PETROS - Worldwide Databank of Major Element Chemical Analyses of Igneous Rocks

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — PETROS is a worldwide data bank of major element chemical analyses of igneous rocks compiled for research and teaching purposes by Dr. Felix Mutschler and Staff at...

  13. Workshop on Evolution of Igneous Asteroids: Focus on Vesta and the HED Meteorites. Pt. 1

    Science.gov (United States)

    Mittlefehldt, David W. (Editor); Papike, James J. (Editor)

    1996-01-01

    This volume contains abstracts of papers that have been accepted for presentation at the Workshop on Evolution of Igneous Asteroids: Focus on Vesta and the HED Meteorites, October 16-18, 1996, in Houston, Texas.

  14. Igneous rocks of alpine age associated with Keuper material in the Iberian Mountains, near Teruel (Spain)

    OpenAIRE

    Sánchez Cela, V.; García Anquela, J. A.

    1984-01-01

    In the present work, some rocks of igneous facies associated to Keuper materials, are studied. These rocks, previously referred to as ophites, consist in fact of plutonic rocks, compositionally ranging from syenites to monzogabbros. Field, petrographic and geochemical data appear to indicate that these igneous rocks facies were a consequence of metasomatic transformation processes that took place between allocthonous silica-alkaline elements and suitable wall-rocks, constituted, in this case,...

  15. Evolution and mineralization of volcanic arc sequences: Tyrone Igneous Complex, Northern Ireland

    OpenAIRE

    Hollis , Steven Philip

    2012-01-01

    The Tyrone Igneous Complex of Northern Ireland forms an integral part of the Grampian-Taconic orogen, linking the well documented sectors of Scotland, western Ireland and Newfoundland. The orogen records the accretion of a series of peri-Laurentian affinity arcs, ophiolites and microcontinental blocks to the Laurentian margin between the Late Cambrian and Middle Ordovician. The Tyrone Igneous Complex is broadly divisible into two distinct units: the c. 484-480 Ma ophiolitic Tyrone Plutonic Gr...

  16. Reverse magnetic anomaly controlled by Permian Igneous rocks in the Iberian Chain (N Spain)

    OpenAIRE

    Calvín,P. Universidad de Zaragoza. Departamento. de Ciencias de la Tierra; Casas, A. M. Universidad de Zaragoza. Departamento. de Ciencias de la Tierra; Villalaín, J. J.; Tierz, P. Universidad de Zaragoza. Departamento. de Ciencias de la Tierra

    2014-01-01

    Two important reverse dipolar magnetic anomalies in the Iberian Chain (Spain) are located over Permian igneous rocks. A detailed study of one of them, the Loscos magnetic anomaly, where the geological structure is well constrained, reveals that the source of the anomaly must be a reverse remanent magnetisation carried by igneous rocks, acquired during the period of the Kiaman reverse magnetic superchron. Magnetic and gravimetric detailed survey (with 50 new gravimetric measurements and 8 main...

  17. Rare-earth element modelling of Archean meta-igneous and igneous rocks, Lake Despair area, northwestern Ontario

    International Nuclear Information System (INIS)

    Archean felsic to intermediate meta-igneous rocks from the Lake Despair area, northwestern Ontario, have highly-fractionated REE patterns (Lasub(N)/Lusub(N) 10-100). They are rich in LREEs (ca. 40-100 x chondrites) and poor in HREEs (ca, 1-7 x chondrites). Simple models for the REEs suggest eclogite-quartz eclogite parents for these rocks. The Footprint Gneiss, the major rock type of the Rainy Lake Batholith, was formed by limited melting (ca. 10%) of a quartz eclogite under hydrous conditions. The putative parent may have been transformed basalt derived from primitive, LREE-rich Archean mantle. The mafic metavolcanic rocks have a REE chemistry similar to modern island-arc or mid-ocean ridge tholeiites. Felsic metavolcanic rocks, and granodiorite from the Northwest Bay complex, have REE abundances compatible with an origin by partial melting (ca. 10%), under hydrous conditions, of quartz eclogite of tholeiitic REE chemistry. The Jackfish Lake plutonic complex, which is composed mostly of diorite, has REE abundances that are best described by 10% melting of eclogite (with tholeiitic-REE chemistry) under hydrous conditions. A small portion of the diorite magma was subsequently fractionated, largely by the early crystallization of amphibole, and formed more leucocratic rock types (e.g. leucodiorite and granodiorite). The REE data were obtained by neutron activation analysis. (Auth.)

  18. Integrating isotopic fingerprinting with petrology: how do igneous rocks evolve?

    Science.gov (United States)

    Davidson, J. P.

    2002-12-01

    In the title of his seminal work, N.L. Bowen recognized the fundamental importance of magmatic evolution in producing the spectrum of igneous rocks. Indeed it is difficult to imagine a hot highly reactive fluid passing through c. 100 km of a chemically distinct medium (lithosphere) without evolving through cooling, crystallization and interaction with the wall rocks. The fact that magmas evolve - almost invariably through open system processes - has been largely marginalized in the past 30 years by the desire to use them as probes of mantle source regions. This perspective has been driven principally by advances offered by isotope geochemistry, through which components and sources can be effectively fingerprinted. Two fundamental observations urge caution in ignoring differentiation effects; 1) the scarcity of truly primary magmas according to geochemical criteria (recognized long ago by petrologists), and 2) the common occurrence of petrographic criteria attesting to open system evolution. Recent advances in multicollector mass spectrometry permit integration of the powerful diagnostic tools of isotope geochemistry with petrographic observations through accurate and precise analysis of small samples. Laser ablation and microdrilling enable sampling within and between mineral phases. The results of our microsampling investigations give widespread support for open system evolution of magmas, and provide insights into the mechanisms and timescales over which this occurs. For example; 1) core-rim decreases in 87Sr/86Sr in zoned plagioclase crystals from 1982 lavas of El Chichon volcano, Mexico, argue that the zoning and isotopic changes are in response to magma recharge mixing with an originally contaminated resident magma; 2) Single grain and intra-grain isotopic analyses of mineral phases from Ngauruhoe andesites (New Zealand) are highly variable, arguing that bulk rock data reflect mechanical aggregations of components which have evolved in discrete domains of the

  19. Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    F. Perry; R. Youngs

    2004-10-14

    The purpose of this scientific analysis report is threefold: (1) Present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the probabilistic volcanic hazard analysis (PVHA) (CRWMS M&O 1996 [DIRS 100116]). Conceptual models presented in the PVHA are summarized and applied in areas in which new information has been presented. Alternative conceptual models are discussed, as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) Present revised probability calculations based on PVHA outputs for a repository footprint proposed in 2003 (BSC 2003 [DIRS 162289]), rather than the footprint used at the time of the PVHA. This analysis report also calculates the probability of an eruptive center(s) forming within the repository footprint using information developed in the PVHA. Probability distributions are presented for the length and orientation of volcanic dikes located within the repository footprint and for the number of eruptive centers (conditional on a dike intersecting the repository) located within the repository footprint. (3) Document sensitivity studies that analyze how the presence of potentially buried basaltic volcanoes may affect the computed frequency of intersection of the repository footprint by a basaltic dike. These sensitivity studies are prompted by aeromagnetic data collected in 1999, indicating the possible presence of previously unrecognized buried volcanoes in the YMR (Blakely et al. 2000 [DIRS 151881]; O'Leary et al. 2002 [DIRS 158468]). The results of the sensitivity studies are for informational purposes only and are not to be used for purposes of assessing repository performance.

  20. Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    The purpose of this scientific analysis report is threefold: (1) Present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the probabilistic volcanic hazard analysis (PVHA) (CRWMS M and O 1996 [DIRS 100116]). Conceptual models presented in the PVHA are summarized and applied in areas in which new information has been presented. Alternative conceptual models are discussed, as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) Present revised probability calculations based on PVHA outputs for a repository footprint proposed in 2003 (BSC 2003 [DIRS 162289]), rather than the footprint used at the time of the PVHA. This analysis report also calculates the probability of an eruptive center(s) forming within the repository footprint using information developed in the PVHA. Probability distributions are presented for the length and orientation of volcanic dikes located within the repository footprint and for the number of eruptive centers (conditional on a dike intersecting the repository) located within the repository footprint. (3) Document sensitivity studies that analyze how the presence of potentially buried basaltic volcanoes may affect the computed frequency of intersection of the repository footprint by a basaltic dike. These sensitivity studies are prompted by aeromagnetic data collected in 1999, indicating the possible presence of previously unrecognized buried volcanoes in the YMR (Blakely et al. 2000 [DIRS 151881]; O'Leary et al. 2002 [DIRS 158468]). The results of the sensitivity studies are for informational purposes only and are not to be used for purposes of assessing repository performance

  1. Early and Late Alkali Igneous Pulses and a High-3He Plume Origin for the Deccan Flood Basalts.

    Science.gov (United States)

    Basu, A R; Renne, P R; Dasgupta, D K; Teichmann, F; Poreda, R J

    1993-08-13

    Several alkalic igneous complexes of nephelinite-carbonatite affinities occur in extensional zones around a region of high heat flow and positive gravity anomaly within the continental flood basalt (CFB) province of Deccan, India. Biotites from two of the complexes yield (40)Ar/(39)Ar dates of 68.53 +/- 0.16 and 68.57 +/- 0.08 million years. Biotite from a third complex, which intrudes the flood basalts, yields an (40)Ar/(39)Ar date of 64.96 +/- 0.1 1 million years. The complexes thus represent early and late magmatism with respect to the main pulse of CFB volcanism 65 million years ago. Rocks from the older complexes show a (3)He/(4)He ratio of 14.0 times the air ratio, an initial (87)Sr/(86)Sr ratio of 0.70483, and other geochemical characteristics similar to ocean island basalts; the later alkalic pulse shows isotopic evidence of crustal contamination. The data document 3.5 million years of incubation of a primitive, high-(3)He mantle plume before the rapid eruption of the Deccan CFB. PMID:17783739

  2. Pollution Across Chinese Provinces

    OpenAIRE

    Catherine Yap Co; Fanying Kong; Shuanglin Lin

    2008-01-01

    We revisit the environmental Kuznets curve (EKC) hypothesis using 1987-1995 data for Chinese provinces. A comparison of off-sample (1996-2004) predictions to actual emissions indicates that more stringent rules are still needed to fight industrial (waste water and dust) pollution. Auxiliary regressions show that conditional on income, northern provinces have lower industrial waste water pollution; non-coastal and provinces with smaller secondary industry shares have lower industrial (waste wa...

  3. North Atlantic Temperature Anomaly

    OpenAIRE

    Vukcevic, M.A.

    2009-01-01

    The author postulates the existence of a high correlation between North Atlantic Temperature Anomaly and the variations of magnetic field over the Hudson Bay region. Post-glacial uplift and convection in the underlying mantle uplift (as reflected in changes of the area's magnetic intensity) are making significant contribution to the Atlantic basin climate change.

  4. The ammonium content in the Malayer igneous and metamorphic rocks (Sanandaj-Sirjan Zone, Western Iran)

    Science.gov (United States)

    Ahadnejad, Vahid; Hirt, Ann Marie; Valizadeh, Mohammad-Vali; Bokani, Saeed Jabbari

    2011-04-01

    The ammonium (NH4+) contents of the Malayer area (Western Iran) have been determined by using the colorimetric method on 26 samples from igneous and metamorphic rocks. This is the first analysis of the ammonium contents of Iranian metamorphic and igneous rocks. The average ammonium content of metamorphic rocks decreases from low-grade to high-grade metamorphic rocks (in ppm): slate 580, phyllite 515, andalusite schist 242. In the case of igneous rocks, it decreases from felsic to mafic igneous types (in ppm): granites 39, monzonite 20, diorite 17, gabbro 10. Altered granitic rocks show enrichment in NH4+ (mean 61 ppm). The high concentration of ammonium in Malayer granites may indicate metasedimentary rocks as protoliths rather than meta-igneous rocks. These granitic rocks (S-types) have high K-bearing rock-forming minerals such as biotite, muscovite and K-feldspar which their potassium could substitute with ammonium. In addition, the high ammonium content of metasediments is probably due to inheritance of nitrogen from organic matter in the original sediments. The hydrothermally altered samples of granitic rocks show highly enrichment of ammonium suggesting external sources which intruded additional content by either interaction with metasedimentary country rocks or meteoritic solutions.

  5. Composition and timing of carbonate vein precipitation within the igneous basement of the Early Cretaceous Shatsky Rise, NW Pacific

    Science.gov (United States)

    Geldmacher, J.; Li, S.; Hauff, F. F.; Garbe-Schoenberg, C.; Yu, S.; Zhao, S.; Rausch, S.

    2013-12-01

    Shatsky Rise is an Early Cretaceous large igneous province located in the NW Pacific ca. 1500 km east of Japan and is the third-largest oceanic plateau on Earth (after Ontong Java and Kerguelen). Numerous calcium carbonate veins were recovered from the igneous basement of Shatsky Rise during Integrated Ocean Drilling Program Expedition 324 (Sager et al., 2010). The chemical (Sr/Ca, Mg/Ca) and isotopic (87Sr/86Sr, 143Nd/144Nd, δ18O, δ13C) compositions of these veins were determined to constrain the timing of vein formation and to provide valuable data for the reconstruction of past seawater composition. A dominant control of seawater chemistry on calcite composition is evident for most investigated vein samples with varying compositional contribution from the basaltic basement. The Sr/Ca ratio of the vein calcite is positively correlated with Mg/Ca and with δ18O, indicating warmer/colder precipitation temperatures with decreasing/increasing Sr/Ca (and Mg/Ca) ratios, respectively. Distinctly higher formation temperatures (as inferred from oxygen isotope ratios) indicative of hydrothermal vein formation are only observed at one site (Site U1350, drilled into the central part of Shatsky Rise). The highest 87Sr/86Sr ratios (least basement influence) of vein samples at each drill site range form 0.707264 to 0.707550 and are believed to best reflect contemporaneous Early Cretaceous seawater composition. In principle, age information can be deduced by correlating these ratios with the global seawater Sr isotope evolution. Since the Sr isotopic composition of seawater has fluctuated three times between the early and mid Cretaceous (McArthur et al., 2001) no unambiguous precipitation ages can be constrained by this method and vein precipitation could have occurred at any time between ˜80 and 140 Ma. However, based on combined chemical and isotopic data and correlations of vein composition with formation depth and inferred temperature, we argue for a rather early

  6. Heat production rate from radioactive elements in igneous and metamorphic rocks in eastern desert, Egypt

    International Nuclear Information System (INIS)

    Radioactive heat - production data of igneous and metamorphic rocks cropping out from the eastern desert are presented. Samples were analysed using low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 Μ Wm-3 (granite). In metamorphic rocks it varies from 0.28 (serpentinite) to 0.91 (metagabroo) Μ W.m-3. The contribution due to U is about (51%), whereas that of Th (31%) and (18%) by K. The corresponding values in igneous rocks are 76%: 19%: 5%, respectively. The calculated values showed good agreement with global values expect in some areas contained granite rocks

  7. Electrical resistivity measurement to predict uniaxial compressive and tensile strength of igneous rocks

    Indian Academy of Sciences (India)

    Sair Kahraman; Tekin Yeken

    2010-12-01

    Electrical resistivity values of 12 different igneous rocks were measured on core samples using a resistivity meter in the laboratory. The resistivity tests were conducted on the samples fully saturated with brine (NaCl solution) and the uniaxial compressive strength (UCS), Brazilian tensile strength, density and porosity values of the samples were determined in the laboratory. The test results were evaluated using simple and multiple regression analysis. It was seen that the UCS and tensile strength values were linearly correlated with the electrical resistivity. The correlation coefficients are generally higher for the multiple regression models than that of the simple regression models. It was concluded that the UCS and tensile strength of igneous rocks can be estimated from electrical resistivity. However, the derived relations are purely empirical and they should be checked for other igneous rocks. The effect of rock types such as sedimentary and metamorphic rocks on the derived equations also needs to be investigated.

  8. Heat production rate from radioactive elements in igneous and metamorphic rocks in Eastern Desert, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abbady, Adel G.E. [Physics department, Faculty of science, South Valley University, Qena (Egypt)]. E-mail: abbady@mailcity.com; El-Arabi, A.M. [Physics department, Faculty of science, South Valley University, Qena (Egypt)]. E-mail: elarabi21@yahoo.com; Abbady, A. [Physics department, Faculty of science, South Valley University, Qena (Egypt)

    2006-01-01

    Radioactive heat-production data of Igneous and Metamorphic outcrops in the Eastern Desert are presented. Samples were analysed using a low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 {mu}W m{sup -3} (granite). In metamorphic rocks it varies from 0.28 (serpentinite ) to 0.91 {mu}W m{sup -3} (metagabbro). The contribution due to U is about 51%, as that from Th is 31% and 18% from K. The corresponding values in igneous rocks are 76%, 19% and 5%, respectively. The calculated values showed good agreement with global values except in some areas containing granites.

  9. Heat production rate from radioactive elements in igneous and metamorphic rocks in Eastern Desert, Egypt

    International Nuclear Information System (INIS)

    Radioactive heat-production data of Igneous and Metamorphic outcrops in the Eastern Desert are presented. Samples were analysed using a low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 μW m-3 (granite). In metamorphic rocks it varies from 0.28 (serpentinite ) to 0.91 μW m-3 (metagabbro). The contribution due to U is about 51%, as that from Th is 31% and 18% from K. The corresponding values in igneous rocks are 76%, 19% and 5%, respectively. The calculated values showed good agreement with global values except in some areas containing granites

  10. Igneous history of the aubrite parent asteroid - Evidence from the Norton County enstatite achondrite

    Science.gov (United States)

    Okada, Akihiko; Keil, Klaus; Taylor, G. Jeffrey; Newsom, Horton

    1988-01-01

    Numerous specimens of the Norton County enstatite achondrite (aubrite) were studied by optical microscopy, electron microprobe, and neutron-activation analysis. Norton County is found to be a fragmental impact breccia, consisting of a clastic matrix made mostly of crushed enstatite, into which are embedded a variety of mineral and lithic clasts of both igneous and impact melt origin. The Norton County precursor materials were igneous rocks, mostly plutonic orthopyroxenites, not grains formed by condensation from the solar nebula. The Mg-silicate-rich aubrite parent body experienced extensive melting and igneous differentiation, causing formation of diverse lithologies including dunites, plutonic orthopyroxenites, plutonic pyroxenites, and plagioclase-silica rocks. The presence of impact melt breccias (the microporphyritic clasts and the diopside-plagioclase-silica clast) of still different compositions further attests to the lithologic diversity of the aubrite parent body.

  11. Timing and chemistry of igneous events associated with the Southern Oklahoma Aulacogen

    Science.gov (United States)

    Charles Gilbert, M.

    1983-05-01

    Igneous activity in the Southern Oklahoma Aulacogen of North America was concentrated in the early rifting stages of aulacogen development. The time span over which liquids rose may not have exceeded 50 m.y. and certainly terminated before the Upper Cambrian. Igneous activity began with three basaltic liquids, stratigraphically identifiable but perhaps not all distinct genetically. This was followed by one large rhyolitic-granitic episode of A-type character. One final basaltic event ended the activity. All the basaltic types seem to be tholeiitic showing more kinship with either the older, Proterozoic North American Midcontinental Rift or the northern part of the Cenozoic Rio Grande Rift, than the Cenozoic East African Rift. Two major uplifts occurred: one between the earlier basalts and the rhyolite, and one much later, after all igneous activity was over, in the Pennsylvanian.

  12. Abstracts of the Atlantic Geoscience Society's 2008 colloquium and annual general meeting

    International Nuclear Information System (INIS)

    The Atlantic Geoscience Society (AGS) hosts annual meetings, workshops and field trips to promote a better understanding of the geology of Atlantic Canada. This colloquium highlighted current research in the Atlantic provinces with special sessions devoted to the influences of genetic and environmental factors on soil geochemistry; mineral deposits research; climate change; sediment dynamics, oceanography and ecology of the Greater Bay of Fundy with scenarios of tidal power development; geochronology of crustal processes; and, Earth-based studies of planetary surfaces. The meeting featured 112 presentations, of which 3 have been catalogued separately for inclusion in this database

  13. Modeling differentiation of Karaj Dam basement igneous rocks (northern Iran)

    Science.gov (United States)

    Esmaeily, D.; M-Mashhour, R.

    2009-04-01

    The Karaj Dam basement igneous body (KDB) is located in the north of city of Karaj, 30 km from city of Tehran, which lies between 35° 50' N to 36° 05' N and between 50° 50' E to 51° 15' E. It is one of the several plutonic bodies within the E-W trending Alborz zone in northern Iran. Following the late Cretaceous orogenic movements, vast volumes of dacite, andesites and basaltic lavas with tuffaceous and other clastic sediments were deposited during Eocene time, forming Karaj Formation in central Iran and Albourz. The KDB is penetrated thorough middle and upper tuff units from Karaj Formation which is underlain by late Jurassic depositions (Shemshak Formation) and overlain by the Neogene red Conglomerates in regard to stratographic consideration. It is mainly composed of a layered series dominated by gabbro, diorite and monzonite, which is a rock sequence formed upward from the lower to upper chilled margins, respectively. The chilled margins, which have gabbroic in composition, show porphyritic texture with euhedral to subhedral plagioclase (andesine & labradorite) and pyroxene (augite) megacrysts up to 5 mm long. These rocks become coarse-grained inward and transform to equigranular texture gradually.In addition, a small fine-grained doleritic stock as well as some doleritic dykes is intrusive into the pyroclastic volcanic rocks of Karaj Formation. It is possible to observe doleritic enclaves included in the KDB, indicating that the KDB are slightly younger than the dolerites. Whole rock geochemistry and mineral chemistry of the plagioclase and pyroxene in various rock samples, suggest differentiation processes. The Mg# of the pyroxene and An% of plagioclase of the contact chilled samples can be used as an indication of the original magma and plotted between the gabbro and monzonitic samples. In addition, increasing of the Mg# within the whole rock samples from the upper of contact chilled, in comparison to the lower one, demonstrates elemental differentiation

  14. Natural zeolites filling amygdales and veins in basalts from the british tertiary igneous province on the isle of skye, scotland

    OpenAIRE

    Triana J M; Herrera J F; A C; Castellanos O.M; Henao J A; William Craig; Roberts Clive

    2012-01-01

    ABSTRACT

    Natural zeolites filling amygdales and veins in tertiary basaltic host rocks on the Isle of Skye (NW Scotland) have been studied in some detail by transmitted light microscopy, scanning electron microscopy and X-ray diffraction techniques . The zeolites and associated minerals so identified in order of their relative time of formation...

  15. Natural zeolites filling amygdales and veins in basalts from the British Tertiary Igneous Province on the Isle of Skye, Scotland

    Directory of Open Access Journals (Sweden)

    Triana J M

    2012-10-01

    Full Text Available

    ABSTRACT

    Natural zeolites filling amygdales and veins in tertiary basaltic host rocks on the Isle of Skye (NW Scotland have been studied in some detail by transmitted light microscopy, scanning electron microscopy and X-ray diffraction techniques . The zeolites and associated minerals so identified in order of their relative time of formation from early to late were nontronite, amorphous silica phases, carbonate phases, chabazite, phillipsite, wairakite, thomsonite, analcime, natrolite and stilbite-type minerals . Zeolite formation in the Skye basalts began with low Si/Al ratio Na zeolites and a gradual increase in Ca content and Si/Al ratio, ending up as Ca zeolites . They were probably formed as a consequence of late-stage hydrothermal activity, although, locally, contact metamorphism may control the process of zeolite formation

    RESUMEN

    Las zeolitas naturales como relleno en amígdalas y venas que ocurren en rocas basálticas Terciarias de la Isla de Skye (NW Escocia han sido estudiadas en detalle por técnicas de microscopía de luz transmitida, microscopía electrónica de barrido y difracción de rayos X. Las zeolitas y los minerales asociados identificados, en orden de su tiempo relativo de formación, son nontronita, fases de sílice amorfa, carbonatos, chabazita, filipsita, wairakita, thomsonita, analcima, natrolita y minerales tipo estilbita. La formación de zeolitas en los basaltos de Skye comenzó con una zeolita rica en Na de baja relación Si/Al y con el aumento gradual en el contenido de Ca y Si/Al, terminó con una zeolita rica en Ca Estas probablemente se formaron como consecuencia de una actividad hidrotermal tardía, aunque localmente un metamorfismo de contacto pudo controlar el proceso de formación de las zeolitas

  16. Assessing SPO techniques to constrain magma flow: Examples from sills of the Karoo Igneous Province, South Africa

    Science.gov (United States)

    Hoyer, Lauren; Watkeys, Michael K.

    2015-08-01

    Shape ellipsoids that define the petrofabrics of plagioclase in Jurassic Karoo dolerite sills in KwaZulu-Natal, South Africa are rigorously constrained using the long axis lengths of plagioclase crystals and ellipse incompatibility. This has been undertaken in order to determine the most effective technique to determine petrofabrics when using the SPO-2003 programme (Launeau and Robin, 2005). The technique of segmenting an image for analysis is scrutinised and as a process is found redundant. A grain size threshold is defined to assist with the varying grain sizes observed within and between sills. Where grains exceed the 0.2 mm size threshold, images should be acquired at a high magnification (i.e., 10 × magnification). Petrofabrics are determined using the foliation and the lineation of the ellipsoid as defined by the maximum and minimum principal axes (respectively) of the resultant ellipsoid. Samples with strongly prolate fabrics are isolated allowing further constraint on the petrofabric to be made. Once the efficacy of the petrofabric determination process has been determined, the resultant foliations (and lineations) then elucidate the most accurate petrofabric attainable. The most accurate petrofabrics will be determined by using the correct magnification when the images are obtained and to run the analyses without segmenting the image. The fabrics of the upper and lower contacts of the Karoo dolerite sills are analysed in detail using these techniques and the fabrics are used as a proxy for magma flow.

  17. On the origin of the Amerasia Basin and the High Arctic Large Igneous Province-Results of new aeromagnetic data

    DEFF Research Database (Denmark)

    Døssing, Arne; Jackson, H.R.; Matzka, Jürgen;

    2013-01-01

    The history of the 2.5 million km2 Amerasia Basin (sensu lato) is in many ways the least known in the global tectonic system. Radically different hypotheses proposed to explain its origin are supported only by inconclusive and/or indirect observations and several outstanding issues on the origin of...... Lomonosov Ridges, enabling the tectonic origin of both the Amerasia Basin and the HALIP to be constrained. A landward Lower Cretaceous ( ~ 138 - 125(120) Ma) giant dyke swarm (minimum 350×800km2) and tentative oceanward Barremian (or alternatively lower Valanginian-Barremian) seafloor spreading anomalies...

  18. Petrogenesis of Igneous-Textured Clasts in Martian Meteorite Northwest Africa 7034

    Science.gov (United States)

    Santos, A. R.; Agee, C. B.; Humayun, M.; McCubbin, F. M.; Shearer, C. K.

    2016-01-01

    The martian meteorite Northwest Africa 7034 (and pairings) is a breccia that samples a variety of materials from the martian crust. Several previous studies have identified multiple types of igneous-textured clasts within the breccia [1-3], and these clasts have the potential to provide insight into the igneous evolution of Mars. One challenge presented by studying these small rock fragments is the lack of field context for this breccia (i.e., where on Mars it formed), so we do not know how many sources these small rock fragments are derived from or the exact formation his-tory of these sources (i.e., are the sources mantle de-rived melt or melts contaminated by a meteorite impactor on Mars). Our goal in this study is to examine specific igneous-textured clast groups to determine if they are petrogenetically related (i.e., from the same igneous source) and determine more information about their formation history, then use them to derive new insights about the igneous history of Mars. We will focus on the basalt clasts, FTP clasts (named due to their high concentration of iron, titanium, and phosphorous), and mineral fragments described by [1] (Fig. 1). We will examine these materials for evidence of impactor contamination (as proposed for some materials by [2]) or mantle melt derivation. We will also test the petrogenetic models proposed in [1], which are igneous processes that could have occurred regardless of where the melt parental to the clasts was formed. These models include 1) derivation of the FTP clasts from a basalt clast melt through silicate liquid immiscibility (SLI), 2) derivation of the FTP clasts from a basalt clast melt through fractional crystallization, and 3) a lack of petrogenetic relationship between these clast groups. The relationship between the clast groups and the mineral fragments will also be explored.

  19. Asymmetry of high-velocity lower crust on the South Atlantic rifted margins and implications for the interplay of magmatism and tectonics in continental break-up

    Directory of Open Access Journals (Sweden)

    K. Becker

    2014-06-01

    Full Text Available High-velocity lower crust (HVLC and seaward dipping reflector sequences (SDRs are typical features of volcanic rifted margins. However, the nature and origin of HVLC is under discussion. Here we provide a comprehensive analysis of deep crustal structures in the southern segment of the South Atlantic and an assessment of HVLC along the margins. Two new seismic refraction lines off South America fill a gap in the data coverage and together with five existing velocity models allow a detailed investigation of the lower crustal properties on both margins. An important finding is the major asymmetry in volumes of HVLC on the conjugate margins. The seismic refraction lines across the South African margin reveal four times larger cross sectional areas of HVLC than at the South American margin, a finding that is in sharp contrast to the distribution of the flood basalts in the Paraná-Etendeka Large Igneous Provinces (LIP. Also, the position of the HVLC with respect to the seaward dipping reflector sequences varies consistently along both margins. Close to the Falkland-Agulhas Fracture Zone a small body of HVLC is not accompanied by seaward dipping reflectors. In the central portion of both margins, the HVLC is below the inner seaward dipping reflector wedges while in the northern area, closer to the Rio Grande Rise/Walvis Ridge, large volumes of HVLC extend far seawards of the inner seaward dipping reflectors. This challenges the concept of a simple extrusive/intrusive relationship between seaward dipping reflector sequences and HVLC, and it provides evidence for formation of the HVLC at different times during the rifting and break-up process. We suggest that the drastically different HVLC volumes are caused by asymmetric rifting in a simple shear dominated extension.

  20. The Law of Element Abundance Relationships in Igneous Rocks Petrogenetically Associated with Fractional Crystallization

    Institute of Scientific and Technical Information of China (English)

    汪云亮; 王旺章

    1991-01-01

    Reported in this paper are:1)the law of element abundance relationships:element abun-dances are of power function with each other in an igneous rock petrogenetically associated with fractional crystallization,2)deduction of the law and relevant parameters:abundance relationship constant(a°) and phase constant? from Henry's law and the law of mass conservation,3)the data basis and evidence of the law of element abundance relationships,4)establishment of the equa-bions for element abundance relationships in igneous rocks formed from the same parental magma during the same fractional crystallization stage ,and all measurable parameters involved in the equations.

  1. the Deep Biosphere Archaeal Microbial Community in Igneous Ocean Crust

    Science.gov (United States)

    Edwards, K. J.

    2014-12-01

    Ridge flank hydrothermal systems represent vast environments that may be habitable by subseafloor microbial life. Oceanic ridge flanks, areas far from the magmatic and tectonic influence of seafloor spreading, comprise one of the largest and least explored microbial habitats on the planet. These potential ecosystems may play a significant role in biogeochemical processes and elemental fluxes that are known to be regulated by these systems. I will discuss the nature of ridge flank hydrothermal environments, and present a framework for delineating a continuum of conditions and processes that are likely to be important for defining subseafloor microbial "provinces." The basis for this framework is three governing conditions that help to determine the nature of subseafloor biomes: crustal age, extent of fluid flow, and thermal state. A brief overview of subseafloor conditions, within the context of these three characteristics for select sites will be described. Technical challenges remain and likely will limit progress in studies of microbial ridge flank hydrothermal ecosystems, which is why it is vital to select and design future studies so as to leverage as much general understanding as possible from work focused at a small number of sites. A characterization framework that perhaps includes alternative or additional physical or chemical characteristics is essential for achieving the greatest benefit from multidisciplinary microbial investigations of oceanic ridge flank hydrothermal systems.

  2. Atlantic Salmon Telemetry Monitoring

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Annual telemetry data are collected as part of specific projects (assessments within watersheds) or as opportunistic efforts to characterize Atlantic salmon smolt...

  3. Palaeozoic and Mesozoic igneous activity in the Netherlands: a tectonomagmatic review

    NARCIS (Netherlands)

    Sissingh, W.

    2004-01-01

    To date, igneous rocks, either intrusive or extrusive, have been encountered in the Palaeozoic-Mesozoic sedimentary series of the Netherlands in some 65 exploration and production wells. Following 17 new isotopic K/Ar age determinations of the recovered rock material (amounting to a total of 28 isot

  4. Application of seismic facies and attributes analysis on the identification of Permian igneous rock

    Institute of Scientific and Technical Information of China (English)

    Xu Yongzhong; Yang Haijun; Liu Yongfu; Wang Shuangshuang; Yang Peng; Zhao Jixiang

    2012-01-01

    Seismic facies and attributes analysis techniques are introduced.The geological characteristics of some oil fields in western China are used in conjunction with drilling results and logging data to identify the lithology,intrusion periods,and distribution range of the Permian igneous rocks in this area.The lithologic classification,the vertical and horizontal distribution,and the intrusion periods of igneous rock were deduced through this study.Combining seismic facies and attributes analysis based on optimization can describe the igneous rock in detail.This is an efficient way to identify lithology and intrusion periods.Using geological data and GR-DT logging cross-plots the Permian igneous rock from TP to TT was divided into three periods.The lithology of the first period is tuff and clasolite with a thickness ranging from 18 to 80 ms.The second is basalt with a thickness ranging from 0 to 20 ms.The third is tuff and clasolite and dacite whose thickness ranges from 60 to 80 ms.These results can help understand the clasolite trap with low amplitude and the lithologic trap of the Carboniferous and Silurian.They can also guide further oil and/or gas exploration.

  5. Biological energy from the igneous rock enhances cell growth and enzyme activity

    Energy Technology Data Exchange (ETDEWEB)

    Lin Y.-L. E-mail: yllin@tmc.edu.tw; Kuo, H.-S; Chen, C.-T.; Kuo, S.-C

    2000-06-01

    Some effects from natural resources might be ignored and unused by humans. Environmental hormesis could be a phenomena necessary to bio-organism existence on earth. Since 1919, radiation and some heavy metal hormesis from the environment were proved in various reports. In this study, igneous rock with very low radioactivity and high ferrous activity was measured by multichannel analyzer and inductively coupled plasma analyzer. The water treated by igneous rock, both directly soaked or indirectly in contact, induced increased activities of glucose oxidase, catalase, peroxidase, and superoxide dismutase. It also increased cell growth of SC-M1, HCT-15, Raji, and fibroblast cell lines. The water after treatment of igneous rock had no change in pH values, but displayed decreased conductivity values. We assume that the igneous rock could transfer energy to water to change the molecular structure or conformation of water cluster, or by radiation hormesis effect could then induce increased enzyme activity and cell growth. It is also possible that the energy from rock may combine radiation hormesis with other transferable biological energy forms to change water cluster conformation.

  6. FeO and MgO in plagioclase of lunar anorthosites: Igneous or metamorphic?

    Science.gov (United States)

    Phinney, W. C.

    1994-01-01

    The combined evidence from terrestrial anorthosites and experimental laboratory studies strongly implies that lunar anorthosites have been subjected to high-grade metamorphic events that have erased the igneous signatures of FeO and MgO in their plagioclases. Arguments to the contrary have, to this point, been more hopeful than rigorous.

  7. Biological energy from the igneous rock enhances cell growth and enzyme activity

    International Nuclear Information System (INIS)

    Some effects from natural resources might be ignored and unused by humans. Environmental hormesis could be a phenomena necessary to bio-organism existence on earth. Since 1919, radiation and some heavy metal hormesis from the environment were proved in various reports. In this study, igneous rock with very low radioactivity and high ferrous activity was measured by multichannel analyzer and inductively coupled plasma analyzer. The water treated by igneous rock, both directly soaked or indirectly in contact, induced increased activities of glucose oxidase, catalase, peroxidase, and superoxide dismutase. It also increased cell growth of SC-M1, HCT-15, Raji, and fibroblast cell lines. The water after treatment of igneous rock had no change in pH values, but displayed decreased conductivity values. We assume that the igneous rock could transfer energy to water to change the molecular structure or conformation of water cluster, or by radiation hormesis effect could then induce increased enzyme activity and cell growth. It is also possible that the energy from rock may combine radiation hormesis with other transferable biological energy forms to change water cluster conformation

  8. Playing jigsaw with Large Igneous Provinces—A plate tectonic reconstruction of Ontong Java Nui, West Pacific

    Science.gov (United States)

    Hochmuth, Katharina; Gohl, Karsten; Uenzelmann-Neben, Gabriele

    2015-11-01

    The three largest Large Igneous Provinces (LIP) of the western Pacific—Ontong Java, Manihiki, and Hikurangi Plateaus—were emplaced during the Cretaceous Normal Superchron and show strong similarities in their geochemistry and petrology. The plate tectonic relationship between those LIPs, herein referred to as Ontong Java Nui, is uncertain, but a joined emplacement was proposed by Taylor (2006). Since this hypothesis is still highly debated and struggles to explain features such as the strong differences in crustal thickness between the different plateaus, we revisited the joined emplacement of Ontong Java Nui in light of new data from the Manihiki Plateau. By evaluating seismic refraction/wide-angle reflection data along with seismic reflection records of the margins of the proposed "Super"-LIP, a detailed scenario for the emplacement and the initial phase of breakup has been developed. The LIP is a result of an interaction of the arriving plume head with the Phoenix-Pacific spreading ridge in the Early Cretaceous. The breakup of the LIP shows a complicated interplay between multiple microplates and tectonic forces such as rifting, shearing, and rotation. Our plate kinematic model of the western Pacific incorporates new evidence from the breakup margins of the LIPs, the tectonic fabric of the seafloor, as well as previously published tectonic concepts such as the rotation of the LIPs. The updated rotation poles of the western Pacific allow a detailed plate tectonic reconstruction of the region during the Cretaceous Normal Superchron and highlight the important role of LIPs in the plate tectonic framework.

  9. Probablistic Analyses of Waste Package Quantities Impacted by Potential Igneous Disruption at Yucca Mountain

    Science.gov (United States)

    Wallace, M. G.; Iuzzolina, H.

    2005-12-01

    A probabilistic analysis was conducted to estimate ranges for the numbers of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analysis includes disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application for the Yucca Mountain Project (YMP). The first scenario, igneous intrusion, investigated the case where one or more igneous dikes intersect the repository. A swarm of dikes was characterized by distributions of length, width, azimuth, and number of dikes and the spacings between them. Through the use in part of a latin hypercube simulator and a modified video game engine, mathematical relationships were built between those parameters and the number of waste packages hit. Corresponding cumulative distribution function curves (CDFs) for the number of waste packages hit under several different scenarios were calculated. Variations in dike thickness ranges, as well as in repository magma bulkhead positions were examined through sensitivity studies. It was assumed that all waste packages in an emplacement drift would be impacted if that drift was intersected by a dike. Over 10,000 individual simulations were performed. Based on these calculations, out of a total of over 11,000 planned waste packages distributed over an area of approximately 5.5 km2 , the median number of waste packages impacted was roughly 1/10 of the total. Individual cases ranged from 0 waste packages to the entire inventory being impacted. The igneous intrusion analysis involved an explicit characterization of dike-drift intersections, built upon various distributions that reflect the uncertainties associated with the inputs. The second igneous scenario, volcanic eruption (eruptive conduits), considered the effects of conduits formed in

  10. PROBABILISTIC ANALYSES OF WASTE PACKAGE QUANTITIES IMPACTED BY POTENTIAL IGNEOUS DISRUPTION AT YUCCA MOUNTAIN

    International Nuclear Information System (INIS)

    A probabilistic analysis was conducted to estimate ranges for the numbers of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analyses include disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application for the Yucca Mountain Project (YMP). The first scenario, igneous intrusion, investigated the case where one or more igneous dikes intersect the repository. A swarm of dikes was characterized by distributions of length, width, azimuth, and number of dikes and the spacings between them. Through the use in part of a latin hypercube simulator and a modified video game engine, mathematical relationships were built between those parameters and the number of waste packages hit. Corresponding cumulative distribution function curves (CDFs) for the number of waste packages hit under several different scenarios were calculated. Variations in dike thickness ranges, as well as in repository magma bulkhead positions were examined through sensitivity studies. It was assumed that all waste packages in an emplacement drift would be impacted if that drift were intersected by a dike. Over 10,000 individual simulations were performed. Based on these calculations, out of a total of over 11,000 planned waste packages distributed over an area of approximately 5.5 km2 , the median number of waste packages impacted was roughly 1/10 of the total. Individual cases ranged from 0 waste packages to the entire inventory being impacted. The igneous intrusion analysis involved an explicit characterization of dike-drift intersections, built upon various distributions that reflect the uncertainties associated with the inputs. The second igneous scenario, volcanic eruption (eruptive conduits), considered the effects of conduits formed in

  11. Geochemistry of Sarvabad basic igneous rocks from northern Sanandaj - Sirjan Magmatic Arc, Iran

    Science.gov (United States)

    Mahmoudi, H.; Ghorbani, M.; Azizi, H.

    2009-12-01

    Sanandaj - Sirjan Magmatic Arc (SSMA) as a segment of Alpine -Himalayan magmatic belt embrace a wide spectrum of igneous rocks, both volcanic and plutonic, from basic to felsic compositions. The igneous rocks which are mainly calc-alkaline are attributed to the subduction of Neotethyan oceanic slab beneath central Iranian plate in Mesozoic time (Berberian and Berberian, 1981; Omrani et al., 2008). In the present study the focus is made on the geochemistry and petrography of igneous rocks from northwestern end of the SSMA, in Sarvabad area, in order to elucidate their geodynamic setting. A set of 30 rock samples were analyzed for major and selected trace elements. Mafic igneous bodies from northern SSMA are regarded as post - collisional plutonic bodies of Eocene - Oligocene age (Ghasemi and Talbot, 2006). Azizi and Moinevaziri (2009) considered the igneous rocks from the northern SSMA, at Sonqor - Baneh area, as the products of subduction that continued to the Paleogene time. Investigations carried out in the course of present study demonstrate that the Sarvabad basic igneous rocks, shown on the magmatic map of Iran (Emami et al., 1993) as gabbroic plutons, are composed of volcanic, subvolcanic and plutonic rocks of basic composition. The silica and Mg number of the rocks vary in the ranges 49-52 wt. % and 54-68, respectively. The volcanic rocks are vitrophyric to porphyritic with some plagioclase, olivine and clinopyroxene microphenocrysts. In the subvolcanic and plutonic bodies, plagioclase, clinopyroxene and some amphibole and Fe-Ti oxides are the major constituents. These igneous rocks indicate tholeitic affinity and cover the typical mantle array on a Zr/Nb vs. Y/Nb plot. Occurrences of a few ultramafic bodies found as metric - size isolated lenses in the basic igneous rocks highlight the spatial characteristic of these rocks; the existence of an ophiolitic rock assemblage nearby. Located toward the southwest of Sarvabad basic igneous rocks, is a Cretaceous

  12. Geochemistry of carbonatites in Maoniuping REE deposit, Sichuan Province, China

    Institute of Scientific and Technical Information of China (English)

    许成; 黄智龙; 刘丛强; 漆亮; 李文博; 管涛

    2003-01-01

    Carbonatites in the Maoniuping REE deposit, Sichuan Province, which are spatially and temporally associated with rare earth mineralization, were emplaced at the time of Himalayan. The rocks are carbonatite-syenite complexes, with the mineral assemblages of calcite-aegirine-acmite- arfvedsonite-mica-orthoclase. The rocks are characterized by the enrichment in incompatible elements, such as Sr, Ba and REE, with C and O isotopic compositions of the "primary igneous carbonatites", relatively high initial 87Sr/86Sr ratios and low ??Nd values. All of these suggest that the rocks were derived from the metasomatic enriched mantle. It is demonstrated by geological and geochemical evidence that the mixing of the Himalayan subducting crustal materials with mantle source EM1 is probably the main factor responsible for the formation of carbonatites. The carbonatite-syenite complexes were generated from liquid immiscibility of CO2-rich alkalic silicate magma, which was derived from partial melting of the metasomatic mantle.

  13. 76 FR 1153 - Atlantic Grid Operations A LLC, Atlantic Grid Operations B LLC, Atlantic Grid Operations C LLC...

    Science.gov (United States)

    2011-01-07

    ... Energy Regulatory Commission Atlantic Grid Operations A LLC, Atlantic Grid Operations B LLC, Atlantic Grid Operations C LLC, Atlantic Grid Operations D LLC and Atlantic Grid Operations E LLC; Notice of... (Commission) Rules of Practice and Procedure, 18 CFR 385.207, and Order No. 679,\\1\\ Atlantic Grid Operations...

  14. Possible Biosphere-Lithosphere Interactions Preserved in Igneous Zircon and Implications for Hadean Earth.

    Science.gov (United States)

    Trail, Dustin; Tailby, Nicholas D; Sochko, Maggie; Ackerson, Michael R

    2015-07-01

    Granitoids are silicic rocks that make up the majority of the continental crust, but different models arise for the origins of these rocks. One classification scheme defines different granitoid types on the basis of materials involved in the melting/crystallization process. In this end-member case, granitoids may be derived from melting of a preexisting igneous rock, while other granitoids, by contrast, are formed or influenced by melting of buried sedimentary material. In the latter case, assimilated sedimentary material altered by chemical processes occurring at the near surface of Earth-including biological activity-could influence magma chemical properties. Here, we apply a redox-sensitive calibration based on the incorporation of Ce into zircon crystals found in these two rock types, termed sedimentary-type (S-type) and igneous-type (I-type) granitoids. The ∼400 Ma Lachlan Fold Belt rocks of southeastern Australia were chosen for investigation here; these rocks have been a key target used to describe and explore granitoid genesis for close to 50 years. We observe that zircons found in S-type granitoids formed under more reducing conditions than those formed from I-type granitoids from the same terrain. This observation, while reflecting 9 granitoids and 289 analyses of zircons from a region where over 400 different plutons have been identified, is consistent with the incorporation of (reduced) organic matter in the former and highlights one possible manner in which life may modify the composition of igneous minerals. The chemical properties of rocks or igneous minerals may extend the search for ancient biological activity to the earliest period of known igneous activity, which dates back to ∼4.4 billion years ago. If organic matter was incorporated into Hadean sediments that were buried and melted, then these biological remnants could imprint a chemical signature within the subsequent melt and the resulting crystal assemblage, including zircon. PMID

  15. Uranium Provinces in China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Three uranium provinces are recognized in China, the Southeast China uranium province, the Northeast China-lnner Mongolia uranium province and the Northwest China (Xinjiang) uranium province. The latter two promise good potential for uranium resources and are major exploration target areas in recent years. There are two major types of uranium deposits: the Phanerozoic hydrothermal type (vein type) and the Meso-Cenozoic sandstone type in different proportions in the three uranium provinces. The most important reason or prerequisite for the formation of these uranium provinces is that Precambrian uranium-enriched old basement or its broken parts (median massifs) exists or once existed in these regions, and underwent strong tectonomagmatic activation during Phanerozoic time. Uranium was mobilized from the old basement and migrated upwards to the upper structural level together with the acidic magma originating from anatexis and the primary fluids, which were then mixed with meteoric water and resulted in the formation of Phanerozoic hydrothermal uranium deposits under extensional tectonic environments. Erosion of uraniferous rocks and pre-existing uranium deposits during the Meso-Cenozoic brought about the removal of uranium into young sedimentary basins. When those basins were uplifted and slightly deformed by later tectonic activity, roll-type uranium deposits were formed as a result of redox in permeable sandstone strata.

  16. Potassium-argon radiometric dates of the mid-atlantic ocean floor

    International Nuclear Information System (INIS)

    The basalt and six trachyte rock samples from the King's Trough in the mid-Atlantic ocean floor have been dated by the conventional potassium-argon method. The basalts give two different ages, 155+/-6 Ma (late Jurassic) and 53+/-6 Ma (lower Eocene), while the trachytes give a range of ages from 31.6+/-0.6 Ma to 35.2=0.2 Ma and an average of 33.0+/=0.4 Ma (lower oligocene). The Lower Eocene age of the in-situ basalt matches the age of the original volcanic activity of the region while the lower Oligocene age is associated with the subsequent faulting event. The late Jurassic age of the erratic basalt is interesting because of the scarcity of extrusive igneous rocks of that age along the margins of the North Atlantic and, therefore,needs to be investigated further. (author). 4 refs. 2 tabs

  17. Atlantic menhaden adult tagging study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Atlantic menhaden are a schooling forage fish species, which are subject to a large commercial purse seine fishery. Atlantic menhaden are harvested for reduction...

  18. Atlantic Equatorial Deep Jets

    OpenAIRE

    Didwischus, Sven-Helge; Brandt, Peter; Greatbatch, Richard John

    2012-01-01

    The Equatorial Deep Jets (EDJ) are a dominant signal in the deep Atlantic at the equator. EDJs are vertical alternating zonal currents with a vertical wavelength of only a few hundred meters. They are found from below the Equatorial Undercurrent down to about 2500m. They were also observed in the Pacific and Indian Ocean. The EDJs are focused on the equator and have a meridional extent of about 1.5°S to 1.5°N. In the Atlantic, EDJs oscillate at a period of about 4.5 years as could be shown by...

  19. Radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico with annotated bibliography

    International Nuclear Information System (INIS)

    The primary objectives of this report are to list known radioactive occurrences in veins and igneous and metamorphic rocks in New Mexico, and to provide an annotated bibliography of geologic reports concerning these regions. Only plutonic, metamorphic, vein, and Precambrian quartz-pebble conglomerate uranium deposits are considered in this report; other nonsandstone uranium deposits (such as shale, limestone, phosphorite, coal, evaporative precipitates, and fossil placer deposits) will be considered at a later time. These objectives were achieved through a literature search. Some field examinations of some of the radioactive occurrences have been completed. A table of known radioactive occurrences in veins and igneous and metamorphic rocks was compiled from the literature (Appendix I)

  20. Radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico with annotated bibliography

    International Nuclear Information System (INIS)

    From an extensive literature search and field examination of 96 nonsandstone radioactive occurrences, the author compiled an annotated bibliography of over 600 citations and a list of 327 radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico. The citations are indexed by individual radioactive occurrence, geographic area, county, fluorspar deposits and occurrences, geochemical analyses, and geologic maps. In addition, the geology, mineralization, and uranium and thorium potential of 41 geographic areas in New Mexico containing known radioactive occurrences in veins and igneous and metamorphic rocks or that contain host rocks considered favorable for uranium or thorium mineralization are summarized. A list of aerial-radiometric, magnetic, hydrogeochemical, and stream-sediment survey reports is included

  1. Precise U-Pb Zircon Dating of the Syenite Phase from the Ditrau Alkaline Igneous Complex

    Directory of Open Access Journals (Sweden)

    Pană Dinu

    2000-04-01

    Full Text Available The Ditrău igneous complex represents the largest alkaline intrusion in the Carpathian-Pannonian region consisting of a plethora of rock types formed by complicated magmatic and metasomatic processes. A detailed U-Pb zircon age study is currently underway and the results for the syenite intrusion phase is reported herein. The U-Pb zircon emplacement age of the syenite of 229.6 +1.7/-1.2 Ma documents the quasi-contemporaneous production and emplacement of the gabbro and syenite magmas. We suggest that the syenite and associated granite formed by crustal melting during the emplacement of the mantle derived gabbroic magma around 230 Ma. The thermal contact aureole produced by the Ditrău alkaline igneous complex constrains the main tectonism recorded by surrounding metamorphic lithotectonic assemblages to be pre-Ladinian.

  2. Mineral exploration in the area of the Fore Burn igneous complex, south-western Scotland

    OpenAIRE

    P M Allen; Cooper, D. C.; Parker, M.E.; Easterbrook, G.D.; Haslam, H.W.

    1982-01-01

    The Fore Burn igneous complex consists mainly of quartz-microdiorite, tonalite and feldspar porphyry forming semiconcordant or concordant bodies within early Devonian volcanic and sedimentary rocks, just north of the Southern Upland Fault, some 24 km east of Girvan. There is evidence that the complex has been folded. Several small bodies of intrusion breccia occur within both the complex and the country rock and there is a zone of monolithologic breccias along a fau...

  3. Atlantic City memories.

    Science.gov (United States)

    Epstein, Franklin H

    2008-04-01

    Fifty years ago, the Atlantic City meetings, held the first week in May of every year, were attended by all the elite of American academic medicine and all who wanted to join that group. Part of the magic of those meetings was that professors and neophytes took each other seriously and talked to each other. PMID:18382726

  4. Atlantic tropical cyclones revisited

    Science.gov (United States)

    Mann, Michael E.; Emanuel, Kerry A.; Holland, Greg J.; Webster, Peter J.

    Vigorous discussions have taken place recently in Eos [e.g., Mann and Emanuel, 2006; Landsea, 2007] and elsewhere [Emanuel, 2005; Webster et al., 2005; Hoyos et al., 2006; Trenberth and Shea, 2006; Kossin et al., 2007] regarding trends in North Atlantic tropical cyclone (TC) activity and their potential connection with anthropogenic climate change. In one study, for example [Landsea, 2007], it is argued that a substantial underestimate of Atlantic tropical cyclone counts in earlier decades arising from insufficient observing systems invalidates the conclusion that trends in TC behavior may be connected to climate change. Here we argue that such connections are in fact robust with respect to uncertainties in earlier observations.Several recent studies have investigated trends in various measures of TC activity. Emanuel [2005] showed that a measure of total power dissipation by TCs (the power dissipation index, or PDI) is highly correlated with August-October sea surface temperatures (SST) over the main development region (MDR) for Atlantic TCs over at least the past half century. Some support for this conclusion was provided by Sriver and Ruber [2006]. Webster et al. [2005] demonstrated a statistically significant increase in recent decades in both the total number of the strongest category cyclones (categories 4 and 5) and the proportion of storms reaching hurricane intensity. Hoyos et al. [2006] showed that these increases were closely tied to warming trends in tropical Atlantic SST, while, for example, the modest decrease in vertical wind shear played a more secondary role. Kossin et al. [2007] called into question some trends in other basins, based on a reanalysis of past TC data, but they found the North Atlantic trends to be robust.

  5. Refractory Minerals in Henan Province

    Institute of Scientific and Technical Information of China (English)

    JIN Qinguo; LI Jing; LIU Jiehua; LIU Yanjun

    2004-01-01

    Henan province is very rich in refractory minerals of many varieties including silica, dolomite, graphite,pearlite, sepiolite, olivine, and sillimanite group minerals, besides the abundant reserves of fireclay and bauxite,which lay a good foundation for the development of the refractories industry of the province. The paper introduces the reserves, distribution and character of the refractory minerals in Henan province.

  6. Archangelsk Province Administration

    International Nuclear Information System (INIS)

    The radioactive waste accumulating in the north of the Russian Federation is generated by naval activity, nuclear ice-breakers of the Murmansk Shipping Company, and shipbuilding and ship repairing companies. This report analyses the situation in the town of Severodvinsk in Archangelsk Province and the proposed plans to prevent radioactive pollution of the territory

  7. Source of Mesozoic intermediate-felsic igneous rocks in the North China craton: Granulite xenolith evidence

    Science.gov (United States)

    Jiang, Neng; Carlson, Richard W.; Guo, Jinhui

    2011-07-01

    Four intermediate to felsic igneous rocks from the Zhangjiakou region, along the northern margin of the North China craton, have magmatic zircon U-Pb ages from 122 to 144 Ma. Two of these samples have inherited zircon U-Pb ages of ~ 2.5 Ga, similar to the zircon ages of rocks from the surrounding granulite terrain. Zircons from two intermediate composition granulite xenoliths (JN0811 and JN0919) in the nearby Cenozoic Hannuoba basalts yield two groups of ages. The rims have concordant Mesozoic ages mostly between 120 and 145 Ma, coeval with the Mesozoic intermediate-felsic magmatism in the region, while the cores have discordant U-Pb ages with upper-intercepts of ~ 2.5 Ga, overlapping the zircon ages of granulite terrain rocks, and lower-intercept ages of ~ 130 Ma, approximating the ages of the Mesozoic intermediate-felsic magmatism. The Sr-Nd isotopic compositions of the Mesozoic intermediate-felsic igneous rocks are completely different from those expected for basaltic melts from either the lithospheric mantle or the asthenospheric mantle, precluding a derivation by extensive fractional crystallization of mantle-derived magmas. The lack of correlation between (86Sr/87Sr)i, εNd(t) and SiO2 for the Mesozoic igneous rocks, the very narrow range of zircon εHf(t) for individual intermediate-felsic igneous rocks, and simple binary mixing calculations argue against them being formed by mixing between mantle-derived magma and preexisting crust that has extremely evolved Sr-Nd isotopic compositions like granulite xenoliths JN0811 and JN0919. Hf isotopic compositions of the Mesozoic zircons and whole-rock geochemistry show that the granulite xenoliths with extremely evolved Sr-Nd isotopic compositions have not undergone partial melting during the Mesozoic and thus do not contribute to the Mesozoic intermediate-felsic magmas. Further comparisons show that the source rocks for the Mesozoic intermediate-felsic magmas likely were late Archean lower crustal rocks similar in

  8. Geological setting, emplacement mechanism and igneous evolution of the Atchiza mafic-ultramafic layered suite in north-west Mozambique

    Science.gov (United States)

    Ibraimo, Daniel Luis; Larsen, Rune B.

    2015-11-01

    The Atchiza mafic and ultramafic-layered suite (hereafter, "Atchiza Suite) crops out in an area 330 km2 west of the Mozambican Tete province. In an early account of the geology of this intrusion, it was considered the continuation of the Great Dyke of Zimbabwe, an idea that was aborted after detailed studies. Nevertheless, the Ni concentrations in the Atchiza outcrop rocks are considerable. Our investigation used field evidence, hand specimens and petrography descriptions, mineral chemistry studies using electron microprobe analysis and tectonic analysis to arrive at a plausible mineralogical composition and understanding of the tectonic setting for the igneous evolution. The mineral composition from the Atchiza Suite indicates that these are cumulates. The magmatic segregation from the petrographic and mineral composition reasoning indicates that dunite-lherzolitic peridotite-olivine gabbro-gabbronorite-gabbro-pegmatitic gabbro is the rock formation sequence. Olivine and chromite were the first phases formed, followed by pyroxene and plagioclase. In addition, it is shown that these minerals are near-liquidus crystallization products of basaltic magma with olivine Fo: 87.06 in dunite, mean values of clinopyroxene are (Wo: 36.4, En: 48.0, Fs: 15.2), orthopyroxene (Wo: 2.95, En: 73.0, Fs: 24.2) and plagioclase An: 71.3, respectively. Opaque minerals comprise Fe-Ti oxides and (Fe, Cr) spinel up to 4.8 vol.%, but chromitite layers are not present. Most of the opaque minerals are interstitial to pyroxene. Sulphides are common in gabbros, with pyrrhotite, pentlandite, chalcopyrite, pyrite and covellite together comprising 0.4-2.0 vol.%. The whole rock Rare Earth Element (REE) concentrations are mainly a result of differentiation, but slight crustal contamination/assimilation contributed to the REE contents. In addition, they also show Eu enrichment, suggesting that plagioclase fractionation was important in the rock. The Atchiza Suite preserves a deep-seated plumbing

  9. Smooth Sailing or Stormy Seas? Atlantic Canadian Physical Educators on the State and Future of Physical Education

    Science.gov (United States)

    Robinson, Daniel B.; Randall, Lynn

    2016-01-01

    This article summarizes results from a recently completed study that focused upon the current state and possible future of physical education within Canada's four Atlantic provinces. Data from both large-scale surveys and eight follow-up focus group interviews are shared as they relate to the state and future of physical education, possible…

  10. Atlantic Basin refining profitability

    International Nuclear Information System (INIS)

    A review of the profitability margins of oil refining in the Atlantic Basin was presented. Petroleum refiners face the continuous challenge of balancing supply with demand. It would appear that the profitability margins in the Atlantic Basin will increase significantly in the near future because of shrinking supply surpluses. Refinery capacity utilization has reached higher levels than ever before. The American Petroleum Institute reported that in August 1997, U.S. refineries used 99 per cent of their capacity for several weeks in a row. U.S. gasoline inventories have also declined as the industry has focused on reducing capital costs. This is further evidence that supply and demand are tightly balanced. Some of the reasons for tightening supplies were reviewed. It was predicted that U.S. gasoline demand will continue to grow in the near future. Gasoline demand has not declined as expected because new vehicles are not any more fuel efficient today than they were a decade ago. Although federally-mandated fuel efficiency standards were designed to lower gasoline consumption, they may actually have prevented consumption from falling. Atlantic margins were predicted to continue moving up because of the supply and demand evidence: high capacity utilization rates, low operating inventories, limited capacity addition resulting from lower capital spending, continued U.S. gasoline demand growth, and steady total oil demand growth. 11 figs

  11. Atlantic Oceanographic and Meteorological Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Atlantic Oceanographic and Meteorological Laboratory conducts research to understand the physical, chemical, and biological characteristics and processes of the...

  12. Two Distinct Roles of Atlantic SSTs in ENSO Variability: North Tropical Atlantic SST and Atlantic Nino

    Science.gov (United States)

    Ham, Yoo-Geun; Kug, Jong-Seong; Park, Jong-Yeon

    2013-01-01

    Two distinct roles of the Atlantic sea surface temperatures (SSTs), namely, the North Tropical Atlantic (NTA) SST and the Atlantic Nino, on the El Nino-Southern Oscillation (ENSO) variability are investigated using the observational data from 1980 to 2010 and coupled model experiments. It appears that the NTA SST and the Atlantic Nino can be used as two independent predictors for predicting the development of ENSO events in the following season. Furthermore, they are likely to be linked to different types of El Nino events. Specifically, the NTA SST cooling during February, March, and April contributes to the central Pacific warming at the subsequent winter season, while the negative Atlantic Nino event during June, July, and August contributes to enhancing the eastern Pacific warming. The coupled model experiments support these results. With the aid of a lagged inverse relationship, the statistical forecast using two Atlantic indices can successfully predict various ENSO indices.

  13. Links between viruses and prokaryotes throughout the water column along a North Atlantic latitudinal transect.

    Science.gov (United States)

    De Corte, Daniele; Sintes, Eva; Yokokawa, Taichi; Reinthaler, Thomas; Herndl, Gerhard J

    2012-08-01

    Viruses are an abundant, diverse and dynamic component of marine ecosystems and have a key role in the biogeochemical processes of the ocean by controlling prokaryotic and phytoplankton abundance and diversity. However, most of the studies on virus-prokaryote interactions in marine environments have been performed in nearshore waters. To assess potential variations in the relation between viruses and prokaryotes in different oceanographic provinces, we determined viral and prokaryotic abundance and production throughout the water column along a latitudinal transect in the North Atlantic. Depth-related trends in prokaryotic and viral abundance (both decreasing by one order of magnitude from epi- to abyssopelagic waters), and prokaryotic production (decreasing by three orders of magnitude) were observed along the latitudinal transect. The virus-to-prokaryote ratio (VPR) increased from ~19 in epipelagic to ~53 in the bathy- and abyssopelagic waters. Although the lytic viral production decreased significantly with depth, the lysogenic viral production did not vary with depth. In bathypelagic waters, pronounced differences in prokaryotic and viral abundance were found among different oceanic provinces with lower leucine incorporation rates and higher VPRs in the North Atlantic Gyre province than in the provinces further north and south. The percentage of lysogeny increased from subpolar regions toward the more oligotrophic lower latitudes. Based on the observed trends over this latitudinal transect, we conclude that the viral-host interactions significantly change among different oceanic provinces in response to changes in the biotic and abiotic variables. PMID:22258100

  14. The wood industry in Atlantic Canada: A focus on value-added

    International Nuclear Information System (INIS)

    This report prepared by the Atlantic Canada Opportunities Agency in consultation with the four Atlantic provinces focuses on the value-added aspects of the wood products industry in Atlantic Canada. It also examines the state of the resource, the state of the industry, productivity and economic benefits, products and markets, trade and regulations, and needs, challenges and targets. The analysis was undertaken to determine the possibility of further utilization of forest resources in the region for value-added products, and to assess the possibilities for the wood products industry of Atlantic Canada exploring world markets for its products. The inventory of resources found 1.4 billion cubic meter of wood-growing productive forest land in the region, with softwoods accounting for 76 per cent of the forests. Concern was expressed about forest stands at regeneration levels. Total Annual Allowable Cut (AAC) for the Atlantic Provinces in 1995 was almost 20 million cubic meter, approximately 10 per cent of the national total. Although total harvests are below the AAC for the region, softwood harvesting in 1994 and in 1995 was well above the AAC. The analysis concluded that given the current level of harvesting, sustained growth in Atlantic Canada's wood industries will have to rely on access to external fibre sources and better use of the existing fibre source. At the same time, since many value-added manufacturers in the region rely on imported wood resources, the health of the value-added wood industry does not appear to be completely dependent on the sustainability of forest resources in the Atlantic region. Part Two of the report provides an economic profile of the industry, including brief reviews on employment, wages and salaries, exports and imports, transportation, education and training, research and technology and marketing. refs., tabs

  15. Lead isotope systematics of some igneous rocks from the Egyptian Shield

    Science.gov (United States)

    Gillespie, J. G.; Dixon, T. H.

    1983-01-01

    Lead isotope data on whole-rock samples and two feldspar separates for a variety of Pan-African (late Precambrian) igneous rocks for the Egyptian Shield are presented. It is pointed out that the eastern desert of Egypt is a Late Precambrian shield characterized by the widespread occurrence of granitic plutons. The lead isotope ratios may be used to delineate boundaries between Late Precambrian oceanic and continental environments in northeastern Africa. The samples belong to three groups. These groups are related to a younger plutonic sequence of granites and adamellites, a plutonic group consisting of older tonalites to granodiorites, and the Dokhan volcanic suite.

  16. Pre-Elsonian mafic magmatism in the Nain Igneous Complex, Labrador: the bridges layered intrusion

    Science.gov (United States)

    Ashwal, L.D.; Wiebe, R.A.; Wooden, J.L.; Whitehouse, M.J.; Snyder, Diane

    1992-01-01

    Decades of work on the pristine, unmetamorphosed, and well exposed anorthositic, mafic and granitic rocks of the Nain igneous complex, Labrador, have led to the conclusion that all plutonic rocks in that area were emplaced in a short time intercal at about 1300 ?? 10 Ma). We report here new isotopic data for mafic intrusive rocks that appear to have crystallized several hundred Ma earlier than the bulk of the plutonic activity in the Nain complex. The Bridges layered intrusion (BLI) is a small (15-20 km2) lens of layered mafic rocks about 1.5 km thick, surrounded and intruded by anorthositic, leuconoritic and leucotroctolitic plutons in the middle of the coastal section of the Nain igneous complex. BLI shows very well developed magmatic structures, including channel scours, slump structures, and ubiquitous modally graded layering. Most rocks, however, show granular textures indicative of recrystallization, presumably caused by emplacement of younger anorthositic rocks. BLI contains cumulate rocks with slightly more primitive mineral compositions (An60-83, Fo66-71) than those of other mafic intrusions in the Nain igneous complex, including Kiglapait. SmNd isotopic data for 7 BLI whole-rocks ranging in composition between olivine melagabbro and olivine leucogabbro yield an age of 1667 ?? 75 Ma, which we interpret as the time of primary crystallization. The internal isotopic systematics of the BLI have been reset, probably by intrusion of adjacent anorthositic plutons. A SmNd mineral isochron (plag, whole-rock, mafics) for a BLI olivine melagabbro gives an age of 1283 ?? 22 Ma, equivalent within error of a mineral array (plag, whole-rock, opx, cpx) for an adjacent, igneous-textured, leuconorite vein (1266 ?? 152 Ma). The initial Nd ratio for BLI corresponds to ??{lunate}Nd = -3.18 ?? 0.44. Other whole-rock samples, however, some with vein-like alteration (Chlorite, serpentine, amphiboles), show ??{lunate}Nd values as low as -9.1, suggesting variable contamination by

  17. Gamma-ray dose rates in igneous rock terrains in the Japanese Islands

    International Nuclear Information System (INIS)

    Air absorbed dose rates evaluated from uranium, thorium and potassium contents in rock samples have been compared with SiO2 and K2O data in order to understand lithologic characteristics of terrestrial γ-ray dose rate levels in igneous rock terrains. The comparison showed that the dose rate increased with increasing SiO2 or K2O content of rock. The models of partial melting of rock and crystallization differentiation of magma were used to analyze this trend quantitatively. As a result, a semi-empirical formula could be derived for expressing the dose rate as a function of K2O content of rock. (author)

  18. The Miocene Atlantic Ocean

    Science.gov (United States)

    Müller, R. D.; Herold, N.; Huber, M.

    2012-04-01

    We model paleoclimate and ocean circulation during the Miocene climatic optimum (~17 ¬ 14.5 Ma) using the Community Climate System Model 3 (CCSM3), focussing particularly on the effect of Miocene model boundary conditions including reconstructed topography, bathymetry, and vegetation. The modelled Miocene climate exhibits broad increases in mean annual precipitation over central and northern Africa, northern Eurasia, northern North America and Greenland compared to the present. In northern Africa, summer precipitation is significantly higher in the Miocene due to the replacement of desert with broadleaf vegetation, consistent with previously published sensitivity studies. Our results qualitatively support interpretations of carbon and neodymium isotope records indicating NCW formation in the North Atlantic as well as a dominant bottom water source in the Southern Ocean. Major tectonic changes in our Miocene Atlantic bathymetry compared to the present day are the severe constriction of the Fram Strait, closure of the Panama Strait and the less elevated Greenland-Scotland Ridge. We find that the structure of ocean circulation in the Miocene Atlantic is somewhat opposite to the present day, with the primary region of Miocene bottom water formation in the Weddell Sea. The strength of Weddell Sea bottom water and North Component Water (NCW) formation are moderated by atmospheric CO2 levels, which suggests that very weak NCW formation could have existed under significantly higher concentrations than the present-day CO2 concentration used in our model. Such a state would be consistent with the hypothesis of negligible NCW formation in the early Miocene, suggested previously. In our model, the NCW is relatively warm and saline compared to modern North Atlantic Deep Water (NADW). This is likely a robust result, caused by a northward deflection of North Atlantic subtropical water below the mixed-layer, a weakening of the subpolar gyre and weaker convection, as opposed to

  19. Biogeographic and species richness patterns of Gastropoda on the southwestern Atlantic

    Directory of Open Access Journals (Sweden)

    FLOETER S. R.

    1999-01-01

    Full Text Available Patterns of richness and biogeography of Gastropoda molluscs were determined based on lists of species from five sites along the southwestern Atlantic. The analysis of the distribution patterns of these sites confirmed the existence of a broader transition zone between southern Espírito Santo State (21°S and Rio Grande do Sul State (32°S. This zone is very heterogeneous, presenting a low endemism rate and a significant number of species common to the near provinces, and does not show enough consistency to be considered as an independent biogeographic province as proposed by Palacio (1980. Observing the distribution of species along the southwestern Atlantic we find an increase in the proportion of species with greatest latitudinal ranges (occurring from the tropics to Patagonia from lowest to highest latitudes, following Rappoport's rule.

  20. Effect of igneous intrusive on coal microconstituents: Study from an Indian Gondwana coalfield

    Energy Technology Data Exchange (ETDEWEB)

    Sarana, Shinjini [Department of Botany, National P.G. College, Lucknow (India); Kar, Ratan [Birbal Sahni Institute of Palaeobotany, Lucknom (India)

    2011-01-01

    Petrological and palynological analyses of coals from two bore-holes, intruded by an igneous body (dolerite dyke), reveal characteristic changes due to thermal alteration. The unaffected coals are high volatile bituminous (Rr: 0.50-0.61%). The coals recovered from samples located close to the dyke had vitrinite with devolatization microvacuoles, higher reflectance ranging from 0.9% to 3.0% and liptinite with none to very low fluorescence. There is an increasing trend in reflectance and a decreasing trend in fluorescence in the samples occurring closer to the dyke. Presence of injected mineral matter and pyrite in the macerals further indicate the impact of thermal metamorphism on the coals occurring near the igneous body. The palynological investigation of unaffected coals shows the presence of a number of well-identified spores and pollen. However, very few palynomorphs could be recovered from coals located close to the intrusive as the pollen/spores were found to be charred beyond recognition. (author)

  1. Floor-fractured impact craters on Venus: Implications for igneous crater modification and local mechanism

    Science.gov (United States)

    Wichman, R. W.; Schultz, P. H.

    1995-02-01

    Regional tectonism and volcanism affect crater modification and crater loss on Venus, but a comparison of Venusian craters to lunar floor-fractured craters suggest that a third style of more localized, crater-controlled magmatism also may occur on Venus. Based on lunar models for such magmatism, Venusian crustal conditions should generally favor crater-filling volcanism over crater-centered floor fracturing. Nevertheless, three craters on Venus strongly resemble extensively modified craters on the Moon where deformation can be attributed to failure over large crater-centered intrusions. Models for crater modification over igneous intrusions indicate typical magmatic pressure beneath these three craters of approximately 200-300 bars and intrusion depths of the order of 1-6 km. All three craters also share common settings and low elevations, whereas craters embayed by regional volcanism preferentially occur at much higher elevations on Venus. We suggest that the style of igneous crater modification on Venus thus may be elevation dependent, with crater-centered intrusions primarily occurring at low elevations on Venus. This interpretation is consistent with theoretically predicted variations in magmatic neutral buoyancy depth as a function of atmospheric pressure suggested by other authors.

  2. Semi-quantitative spectrographic determination of traces of elements in igneous rocks

    International Nuclear Information System (INIS)

    A semi-quantitative spectrographic technique based on Harveys'method, using background radiation as internal standard is described for the analysis of trace elements in igneous rocks by the total energy method. A certain amount of the sample was completely vapourized in a DC arc with anodic excitation under argon and oxygen atmosphere, using graphite electrodes of standard dimensions. In the processed film, selected lines and adjancent backgrounds were evaluated by densitometry and the corresponding intensity ratios were calculated. Sensitivity factors were determined for the analytical lines of Co, Cu, Ga, Ni, Sc, Sr, V, Y, Zn, and Zr in geological standards (G-2, BCR-1, AGV-1, GSP-1) from the United States Geological Survey. Matrix effects between samples and standards were minimized by using the above mentioned geological standards. An average value of the sensitivity factors was employed for the calculation of the concentration of the elements in the samples. A comparison between the results obtained by this method and those from the analysis of zinc by atomic absorption is presented. This method enabled the analyses of igneous rock samples having SiO2 contents between 40 and 80%, with an error in the determinations of trace elements less than 30%.(Author)

  3. Postcollisional mafic igneous rocks record crust-mantle interaction during continental deep subduction.

    Science.gov (United States)

    Zhao, Zi-Fu; Dai, Li-Qun; Zheng, Yong-Fei

    2013-01-01

    Findings of coesite and microdiamond in metamorphic rocks of supracrustal protolith led to the recognition of continental subduction to mantle depths. The crust-mantle interaction is expected to take place during subduction of the continental crust beneath the subcontinental lithospheric mantle wedge. This is recorded by postcollisional mafic igneous rocks in the Dabie-Sulu orogenic belt and its adjacent continental margin in the North China Block. These rocks exhibit the geochemical inheritance of whole-rock trace elements and Sr-Nd-Pb isotopes as well as zircon U-Pb ages and Hf-O isotopes from felsic melts derived from the subducted continental crust. Reaction of such melts with the overlying wedge peridotite would transfer the crustal signatures to the mantle sources for postcollisional mafic magmatism. Therefore, postcollisonal mafic igneous rocks above continental subduction zones are an analog to arc volcanics above oceanic subduction zones, providing an additional laboratory for the study of crust-mantle interaction at convergent plate margins. PMID:24301173

  4. Igneous rocks of alpine age associated with Keuper material in the Iberian Mountains, near Teruel (Spain

    Directory of Open Access Journals (Sweden)

    Sánchez Cela, V.

    1984-04-01

    Full Text Available In the present work, some rocks of igneous facies associated to Keuper materials, are studied. These rocks, previously referred to as ophites, consist in fact of plutonic rocks, compositionally ranging from syenites to monzogabbros. Field, petrographic and geochemical data appear to indicate that these igneous rocks facies were a consequence of metasomatic transformation processes that took place between allocthonous silica-alkaline elements and suitable wall-rocks, constituted, in this case, of evaporitic marls of Keuper facies.

    Se describen algunos caracteres geológicos, petrográficos y geoquímicos de unas rocas ígneas, que en pequeños afloramientos aparecen asociadas a materiales del Keuper. Estas rocas, que estaban citadas como ofitas, corresponden principalmente a facies granudas entre sienitas y monzogabros. El ambiente de los afloramientos, relaciones de contacto, caracteres petrográficos y químicos, parecen indicar que las rocas ígneas fueron el resultado de procesos de metasomatismo originados por fluidos sílico-alcalinos que transformaron los materiales encajantes margoevaporíticos del Keuper.

  5. Correlation between parent and daughter element concentrations as a means of valuing isochrons of igneous rocks

    International Nuclear Information System (INIS)

    The question whether a series of samples from an igneous rock can be attributed to an isochron for radiogeochronological dating or for determining the initial isotope ratio of the daughter element of the radioactive decay can be valued by investigating the correlation between the concentrations 1c and 2c of mother (1c) and daughter element (2c). The slope of the regression line in a lg 1c to lg 2c diagram is given by 1D - 1/2D - 1 or 1D - 1/2D - 1 · 2D/1D, where 1D and 2D are the solid-liquid distribution coefficients of parent and daughter element, if the concentration patterns are ruled by fractional crystallization or by partial melting, respectively. The agreement between experimentally found slopes and those calculated from distribution coefficients thus gives additional evidence whether or not the isochron reflects a magma solidification or magma generation age, respectively. The method is discussed for the Rb-Sr-, Sm-Nd-, La-Ce-, La-Ba- and K-Ca-geochronometers, using distribution coefficients calculated on the basis of a global model of the generation of the most abundant continental igneous rocks. The application on Rb-Sr-isochrons of a series of various granites of the Erzgebirge and the Saxonian Granulite Massif in the Southern Part of the GDR reveals new evidence of postmagmatic autosomatosis having altered the chemical composition of the Younger granites of the Western Ore Mountains (Erzgebirge). (author)

  6. Magnetic petrofabric of igneous rocks: Lessons from pyroclastic density current deposits and obsidians

    Science.gov (United States)

    Cañón-Tapia, E.; Mendoza-Borunda, R.

    2014-12-01

    Measurement of the anisotropy of magnetic susceptibility (AMS) of igneous rocks can provide clues concerning their mechanism of formation and in particular are very helpful as flow direction indicators. Unlike other igneous rocks, however, pyroclastic density current deposits (PDCDs) present a challenge in the interpretation of AMS measurements due to the complexity of their mechanism of emplacement. In this paper we review the most common assumptions made in the interpretation of the AMS of PDCD, taking advantage of key lessons obtained from obsidians. Despite the complexities on the mechanism of formation of PDCDs, it is shown that a key element for the fruitful interpretation of AMS is to give proper attention to the various components likely to be involved in controlling their general petrofabric. The anisotropies of ferromagnetic crystals (whether as free phases or embedded within clasts or shards), and those of paramagnetic minerals (mainly ferrosilicates) need to be taken into consideration when interpreting the AMS measurements of PDCDs. Variations of the deposition regime both as a function of position and of time also need to be considered on the interpretations. Nevertheless, if a suitable sampling strategy is adopted, the potential of the AMS method as a petrofabric indicator is maximized.

  7. Book Review: Potassic igneous rocks and associated gold-copper mineralization, Fourth edition (D. Muller and D.I. Groves)

    Science.gov (United States)

    Kelley, Karen Duttweiler

    2016-01-01

    The fourth edition of this comprehensive textbook, which succeeds those published in 1995, 1997, and 2000, very nicely summarizes the geochemical and petrological characteristics of potassic igneous rock complexes and the different tectonic settings in which they occur. The authors provide an overview and a classification of these rocks and they outline the geochemical differences between barren and mineralized potassic igneous complexes. Owing to the common association of potassic igneous rocks with many gold- and copper-rich ore deposits, this book will be of interest not only to research scientists but also to those exploring for major deposits in young and ancient terranes. In fact, there was a clear attempt by the authors to provide a good mix of theoretical discussions based on experimental work, with case studies that illustrate field and applied research.

  8. Trindade and Martı´n Vaz Islands, South Atlantic: Isotopic (Sr, Nd, Pb) and trace element constraints on plume related magmatism

    Science.gov (United States)

    Siebel, W.; Becchio, R.; Volker, F.; Hansen, M. A. F.; Viramonte, J.; Trumbull, R. B.; Haase, G.; Zimmer, M.

    2000-05-01

    basalts from the Late Cretaceous Poxoreu igneous province (inland Brazil) and the Eocene Abrolhos platform (Brazilian Atlantic margin). Simple batch-melting considerations indicate that the degree of melting has decreased from Poxoreu through Abrolhos to Trindade. These estimates might suggest a diminishing thermal input of the Trindade mantle plume through time.

  9. Building the EarthChem System for Advanced Data Management in Igneous Geochemistry

    Science.gov (United States)

    Lehnert, K.; Walker, J. D.; Carlson, R. W.; Hofmann, A. W.; Sarbas, B.

    2004-12-01

    Several mature databases of geochemical analyses for igneous rocks are now available over the Internet. The existence of these databases has revolutionized access to data for researchers and students allowing them to extract data sets customized to their specific problem from global data compilations with their desktop computer within a few minutes. Three of the database efforts - PetDB, GEOROC, and NAVDAT - have initiated a collaborative effort called EarthChem to create better and more advanced and integrated data management for igneous geochemistry. The EarthChem web site (http://www.earthchem.org/) serves as a portal to the three databases and information related to EarthChem activities. EarthChem participants agreed to establish a dialog to minimize duplication of effort and share useful tools and approaches. To initiate this dialog, a workshop was run by EarthChem in October, 2003 to discuss cyberinfrastructure needs in igneous geochemistry (workshop report available at the EarthChem site). EarthChem ran an information booth with database and visualization demonstrations at the Fall 2003 AGU meeting (and will have one in 2004) and participated in the May 2003 GERM meeting in Lyon, France where we provided the newly established Publishers' Round Table a list of minimum standards of data reporting to ease the assimilation of data into the databases. Aspects of these suggestions already have been incorporated into new data policies at Geochimica et Cosmochimica Acta and Chemical Geology (Goldstein et al. 2004), and are under study by the Geological Society of America. EarthChem presented its objectives and activities to the Solid Earth Sciences community at the Annual GSA Meeting 2003 (Lehnert et al, 2003). Future plans for EarthChem include expanding the types and amounts of data available from a single portal, giving researchers, faculty, students, and the general public the ability to search, visualize, and download geochemical and geochronological data for a

  10. Geochemical characteristics of Cenozoic high-K igneous rocks from Liuhe-Xiangduo area, eastern Tibet

    Institute of Scientific and Technical Information of China (English)

    WEI Qirong; WANG Jianghai

    2005-01-01

    The major elements, trace elements and Nd-Sr isotopic composition of Cenozoic high-K igneous rocks and mafic deep-derived enclaves from the Liuhe-Xiangduo area, eastern Tibet, indicate the high-K igneous rocks are characterized as being enriched in Ca (CaO= 1.20% - 8.80% ), alkali (Na2O+K2O= 3.47% - 10.65% ), especially K (K2O up to 5.96% ) and depleted in Ti (TiO2= 0.27% - 1.50% ). Their REE contents are very high (REE= 91.29 - 231.11 μg/g). Their REE distribution patterns are of the right-inclined type, characterized by intense LREE enrichment [(La/Yb)N= 7.44 - 15.73 ]. The rocks are distinctly enriched in Rb, Sr and Ba ( 46.3 -316 μg/g, 349-1220 μg/g and 386-2394 μg/g, respectively), high in U and Th ( 1.17 - 8.10 μg/g and 2.58 - 27.0 μg/g, respectively), moderate in Zr and Hf ( 87.5 -241 μg/g and 2.83 - 7.52 μg/g, respectively), and depleted in Nb and Ta ( 4.81 - 16.8 μg/g and 0.332 - 1.04 μg/g, respectively). In the primitive mantle-normalized incompatible element spidergram, U, K, Sr and Hf show positive anomalies, whereas Th, Nb, Ta, P, and Ti show negative anomalies. The rocks are strongly depleted in Cr and Ni ( 21.4 -1470 μg/g and 7.79 -562 μg/g, respectively), and their transition element distribution curves are obviously of type-W. The ( 87 Sr/ 86 Sr)i ratios range from 0.704184 to 0.707539 ; ( 143 Nd / 144 Nd)i from 0.512265 to 0.512564 ; and ε Nd (t) from -6.3 to -0.4 . These geochemical features might suggest that the potential source of the high-K igneous rocks in the Liuhe-Xiangduo area is similar to the EM2, which may be similar to the material enriched K that is located under the crust-mantle mixed layer. The mafic deep-derived enclaves in the high-K igneous rocks belong to chance xenoliths. Their ( 87 Sr/ 86 Sr)i ratios range from 0.706314 to 0.707198 ; ( 143 Nd / 144 Nd)i from 0.512947 to 0.513046 ; and ε Nd (t) from +7.0 to +9.0 . These geochemical features might indicate that the enclaves probably came from the depleted mantle

  11. Evolution of KREEP - Further petrologic evidence. [igneous rocks from Apollo 15 site

    Science.gov (United States)

    Crawford, M. L.; Hollister, L. S.

    1977-01-01

    It is hypothesized that KREEP samples from the Apollo 15 site are igneous. To support the hypothesis, comparisons are made with other crystalline KREEP samples, especially 14310. It is noted that the low siderophile element content and lack of high pressure phenocrysts in the Apollo 15 KREEP may be indications of a slower rise of KREEP melt to the surface, when contrasted with sample 14310. Gravitational separation of Fe-Ni metal is proposed as a mechanism to account for the depletion of siderophile elements relative to the Si-rich component. It is further suggested that KREEP may be the parent of Apollo 12 and 15 basalts, as well as of granitic rocks, due to the liquid immiscibility occurring during the KREEP melt crystallization, and the subsequent independent evolution of the components.

  12. In situ Detection of Microbial Life in the Deep Biosphere in Igneous Ocean Crust

    Science.gov (United States)

    Salas, Everett C.; Bhartia, Rohit; Anderson, Louise; Hug, William F.; Reid, Ray D.; Iturrino, Gerardo; Edwards, Katrina J.

    2015-01-01

    The deep biosphere is a major frontier to science. Recent studies have shown the presence and activity of cells in deep marine sediments and in the continental deep biosphere. Volcanic lavas in the deep ocean subsurface, through which substantial fluid flow occurs, present another potentially massive deep biosphere. We present results from the deployment of a novel in situ logging tool designed to detect microbial life harbored in a deep, native, borehole environment within igneous oceanic crust, using deep ultraviolet native fluorescence spectroscopy. Results demonstrate the predominance of microbial-like signatures within the borehole environment, with densities in the range of 105 cells/mL. Based on transport and flux models, we estimate that such a concentration of microbial cells could not be supported by transport through the crust, suggesting in situ growth of these communities. PMID:26617595

  13. Sepctral Reflectance of Recently Fallen Chondrites and Some Igneous Rocks in China

    Institute of Scientific and Technical Information of China (English)

    林文祝; 高来之

    1991-01-01

    Polarization and radiation measurements and microwave studies show that the planets and the great majority of asteroids in the solar system are covered by soils similar to regolith on the moon surface.The soils repesent the composition of the asteroids and the geological elements of the planets. The spectral reflectance shows a tendency of decreasing from near ultraviolet,visible to near-infrared in order of LL→L→H→H with increasing Fe0/Fet rato and toward to absorption for Jilin,Xinyang and Zanoyang ordinary chondrites and Qinzhen enstatite chondrite recently fallen in China,The same chemical group of meteorites feature deeper absorption valleys with increasing metamorphic grade.The spectal reflectance of igneous rocks varies from strong to what is like that of H-group chondrites in order of acid→basic→ultrabasic rocks.

  14. An Igneous Origin for Features of a Candidate Crater-Lake System in Western Memnonia, Mars

    Science.gov (United States)

    Leverington, D. W.; Maxwell, T. A.

    2004-01-01

    The association of channels, inner terraces, and delta-like features with Martian impact craters has previously been interpreted as evidence in favor of the past existence of crater lakes on Mars. However, examination of a candidate crater-lake system in western Memnonia suggests instead that its features may have formed through igneous processes involving the flow and ponding of lava. Accumulations of material in craters and other topographic lows throughout much of the study region have characteristics consistent with those of volcanic deposits, and terraces found along the inner flanks of some of these craters are interpreted as having formed through drainage or subsidence of volcanic materials. Channels previously identified as inlets and outlets of the crater-lake system are interpreted instead as volcanic rilles. These results challenge previous interpretations of terrace and channel features in the study region and suggest that candidate crater lakes located elsewhere should be reexamined.

  15. High radioactive heat-producing, economically potential granites around Jodhpur city, Malani Igneous Suite, Northwestern India

    International Nuclear Information System (INIS)

    In the south and southeast periphery of the desert city of Jodhpur, there are pink and grey granite islands in the desert sand at Fitkasni-Rasida and Salawas-Nandanvan areas of Malani Igneous Suite (Neoproterozoic). We are reporting the average heat generation value of 15.33 HGU for first and 8.83 HGU for the second area that is much higher than the average (3.8 HGU) known for the continental crust. The concentration of uranium determined is two to four times higher than the average continental crust and thorium is still higher than U and K. The radioelement concentration (Ur) varies from 25.06 to 27 in the Salawas-Nandanvan granites and 43.73 to 75.81 in Fitkasni-Rasida granites. It clearly indicates a 'hot crust', hence favourable for the formation of mineralization of HFS elements, Nb, Ce, REE, U and Th, which need yet to be explored. (author)

  16. A Fungal-Prokaryotic Consortium at the Basalt-Zeolite Interface in Subseafloor Igneous Crust.

    Directory of Open Access Journals (Sweden)

    Magnus Ivarsson

    Full Text Available We have after half a century of coordinated scientific drilling gained insight into Earth´s largest microbial habitat, the subseafloor igneous crust, but still lack substantial understanding regarding its abundance, diversity and ecology. Here we describe a fossilized microbial consortium of prokaryotes and fungi at the basalt-zeolite interface of fractured subseafloor basalts from a depth of 240 m below seafloor (mbsf. The microbial consortium and its relationship with the surrounding physical environment are revealed by synchrotron-based X-ray tomographic microscopy (SRXTM, environmental scanning electron microscopy (ESEM, and Raman spectroscopy. The base of the consortium is represented by microstromatolites-remains of bacterial communities that oxidized reduced iron directly from the basalt. The microstromatolites and the surrounding basalt were overlaid by fungal cells and hyphae. The consortium was overgrown by hydrothermally formed zeolites but remained alive and active during this event. After its formation, fungal hyphae bored in the zeolite, producing millimetre-long tunnels through the mineral substrate. The dissolution could either serve to extract metals like Ca, Na and K essential for fungal growth and metabolism, or be a response to environmental stress owing to the mineral overgrowth. Our results show how microbial life may be maintained in a nutrient-poor and extreme environment by close ecological interplay and reveal an effective strategy for nutrient extraction from minerals. The prokaryotic portion of the consortium served as a carbon source for the eukaryotic portion. Such an approach may be a prerequisite for prokaryotic-eukaryotic colonisation of, and persistence in, subseafloor igneous crust.

  17. Relationships between gas geochemistry and release rates and the geomechanical state of igneous rock massifs

    Science.gov (United States)

    Nivin, Valentin A.; Belov, Nikolai I.; Treloar, Peter J.; Timofeyev, Vladimir V.

    2001-07-01

    In contrast to sedimentary sequences, the relationships between the stressed state of igneous rocks and the chemistry and physical properties of gases contained within them are not well known. Here, we attempt to fill this gap by using, as an example, the apatite-nepheline and rare-metal ore deposits hosted within the Khibiny and Lovozero alkaline nepheline-syenite complexes of the Kola Peninsula, NW Russia. These massifs are characterized by unusually high, for igneous rocks, contents of multi-component, essentially hydrogen-hydrocarbon, gases and also by high hardness, elasticity and unevenly distributed, subhorizontal tectonic stresses. Relationships between the chemical and dynamic characteristics of the gases and the geomechanical properties of the host rocks have been examined using field observations and laboratory experiments. Patterns of gas release variations in time and space, gas emissions from rock pillars during artificial loading, variations of gas pressure in sealed shot-holes and changes in liberation rates of gaseous components during experimental rock loading are suggested to result from changes in rock stress and deformation state. Gas compositions in sealed shot-holes in stressed rocks change with time. Partly, this is due to belated release of gases held in fluid inclusions and isolated voids and their subsequent mixing with gases held in interconnected fracture systems as the included gases are preferentially released as fluid inclusion arrays are opened during later stages of stress build-up. Partly, it may also be because released gases may react with new fracture surfaces to generate enhanced levels of reduced H 2 gases.

  18. VA Atlantic Coast Recreational Use

    Data.gov (United States)

    Virginia Department of Environmental Quality — As a member of the Mid-Atlantic Regional Council on the Ocean (MARCO), Virginia, through its Coastal Zone Management (CZM) Program, collected information on how the...

  19. Atlantic Offshore Seabird Dataset Catalog

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Several bureaus within the Department of Interior compiled available information from seabird observation datasets from the Atlantic Outer Continental Shelf into a...

  20. Virginia Atlantic Coast Recreational Use

    Data.gov (United States)

    Virginia Department of Environmental Quality — As a member of the Mid-Atlantic Regional Council on the Ocean (MARCO), Virginia, through its Coastal Zone Management (CZM) Program, collected information on how the...

  1. A tale of two extinctions : converging end-Permian and end-Triassic scenarios

    NARCIS (Netherlands)

    van de Schootbrugge, Bas; Wignall, Paul B.

    2016-01-01

    The end-Permian (c. 252 Ma) and end-Triassic (c. 201 Ma) mass-extinction events are commonly linked to the emplacement of the large igneous provinces of the Siberia Traps and Central Atlantic Magmatic Province, respectively. Accordingly, scenarios for both extinctions are increasingly convergent and

  2. Microbial assemblages on a cold-water coral mound at the SE Rockall Bank (NE Atlantic): interactions with hydrography and topography

    NARCIS (Netherlands)

    van Bleijswijk, J.D.L.; Whalen, C.; Duineveld, G.C.A.; Lavaleye, M.S.S.; Witte, H.J.; Mienis, F

    2015-01-01

    This study characterizes the microbial community composition over Haas Mound, one of the most prominent cold-water coral mounds of the Logachev Mound province (Rockall Bank, NE Atlantic). We outline patterns of distribution vertically – from the seafloor to the water column – and laterally – across

  3. Medicinal plants of Kermanshah province

    OpenAIRE

    Mostafa Nemati Paykani; Nastaran Jalilian

    2012-01-01

    In order to collect and determine medicinal plants of Kermanshah province, at first a list of medicinal plants and their localities was prepared based on the floristic list of the Kermanshah province mentioned as medicinal plants in the related references. Then, stands of the mentioned medicinal plants were referred according to the topographic maps and the extracted localities and after collecting medicinal plant specimens, herbarium specimens were prepared based on the traditional taxonomic...

  4. Entrepreneur achievement. Liaoning province.

    Science.gov (United States)

    Zhao, R

    1994-03-01

    This paper reports the successful entrepreneurial endeavors of members of a 20-person women's group in Liaoning Province, China. Jing Yuhong, a member of the Family Planning Association at Shileizi Village, Dalian City, provided the basis for their achievements by first building an entertainment/study room in her home to encourage married women to learn family planning. Once stocked with books, magazines, pamphlets, and other materials on family planning and agricultural technology, dozens of married women in the neighborhood flocked voluntarily to the room. Yuhong also set out to give these women a way to earn their own income as a means of helping then gain greater equality with their husbands and exert greater control over their personal reproductive and social lives. She gave a section of her farming land to the women's group, loaned approximately US$5200 to group members to help them generate income from small business initiatives, built a livestock shed in her garden for the group to raise marmots, and erected an awning behind her house under which mushrooms could be grown. The investment yielded $12,000 in the first year, allowing each woman to keep more than $520 in dividends. Members then soon began going to fairs in the capital and other places to learn about the outside world, and have successfully ventured out on their own to generate individual incomes. Ten out of twenty women engaged in these income-generating activities asked for and got the one-child certificate. PMID:12287775

  5. Long-term landscape evolution of the South Atlantic passive continental margin along the Kaoko- and Damara Belts, NW-Namibia

    Science.gov (United States)

    Menges, Daniel; Glasmacher, Ulrich Anton; Hackspacher, Peter; Schneider, Gabriele; Salomon, Eric

    2015-04-01

    The Kaoko Belt in northwestern Namibia originates in the collision of the Rio de la Plata and Kongo Craton during the Pan-African Orogeny in the Neoproterozoic (1) and represents the northern arm of the Damara Orogen. NW-Namibias continental crust mainly consists of the NE-SW striking intracontinental branch of the Pan-African Damara mobile belt, which separates the Congo from the Kalahari craton. The Damara Orogen is divided into several tectonostratigraphic zones that are bounded by steeply dipping, ductile shear zones. These regional lineaments can be traced at least 150 km offshore (2). The lithostratigraphic units consist of Proterozoic and Cambrian metamorphosed rocks (534 (7) Ma - 481 (25) Ma (3) as well as Mesozoic sedimentary and igneous rocks. From Permo-Carboniferous to Mid Jurassic northern Namibia was affected by deep erosion of the Damara Orogen, Permo-Triassic collisional processes along the southern margin of Gondwana and eastern margin of Africa (4), and the deposition of the Nama Group sediments and the Karoo megasequence (5). Between the Otjihorongo and the Omaruru Lineament-Waterberg Thrust early Mesozoic tectonic activity is recorded by coarse clastic sediments deposited within NE trending half-graben structures. The Early Jurassic Karoo flood basalt lavas erupted rapidly at 183±1 Ma (6). The Early Cretaceous Paraná-Etendeka flood basalts (132±1 Ma) and mafic dike swarms mark the rift stage of the opening of the South Atlantic (7). Early Cretaceous alkaline intrusions (137-124 Ma) occur preferentially along Mesozoic half-graben structures and are called the Damaraland Igneous Province (8). Late Cretaceous alkaline intrusions and kimberlite pipes occur in northern Namibia. Post Early Paleocene siliciclastic sedimentation in Namibia was largely restricted to a 150 km wide zone (9) and is represented by the Tsondab Sandstone Formation (~ 300 m thickness). The oldest part has an age of early Paleocene and the upper part span from middle Miocene

  6. Metamorphic and thermal evolution of large contact aureoles - lessons from the Bushveld Igneous Complex

    Science.gov (United States)

    Waters, D.

    2012-04-01

    Large igneous intrusions crystallise, cool, and transfer heat out into their host rocks. The thermal structure of the resulting aureole can be mapped as a series of assemblage zones and isograds, and can in principle be modelled on the assumption that heat transfer is dominantly by conduction. The local peak of contact metamorphism occurs later in time with increasing distance from the igneous contact. The importance of fluids as a metamorphic/metasomatic agent or heat transfer mechanism depends on volatile contents of magma and country rock, and on the geometry of the intrusion. Many of these features are spectacularly illustrated by the aureole beneath the mafic Rustenburg Layered Suite of the Bushveld Complex, which was emplaced at ca. 2060 Ma sub-concordantly into the shale-quartzite succession of the Pretoria Group in the Transvaal Basin. The layered suite reaches a thickness of at least 8 km, and the metamorphic aureole extends 4 km or more downwards into the "floor" of the intrusion. The great extent and relative absence of deformation make this a remarkable natural laboratory for studying the fundamental processes of metamorphism. In quantifying the thermal history, however, a number of second-order factors need to be taken into account. The first relates to the markedly different thermal properties of the major quartzite and shale units, and the second to the importance of endothermic metamorphic reactions in shale units relative to the quartzites. Further insights into metamorphic processes arise from the exquisite detail of poikiloblast growth microstructures preserved in graphite-poor metapelites of the Timeball Hill and Silverton Formations, 2.5 to 3.5 km beneath the igneous contact. These allow a detailed reconstruction of the time sequence of mineral growth and replacement, revealing a marked overlap of the growth intervals of porphyroblastic staurolite, cordierite, biotite, garnet and andalusite at the expense of muscovite, chlorite and chloritoid

  7. Igneous geology of the Carlin trend, Nevada: The importance of Eocene magmatism in gold mineralization

    Science.gov (United States)

    Ressel, Michael Walter, Jr.

    Igneous rocks of five ages are present in the Carlin trend, Nevada, and include: (1) Paleozoic basalt of the Roberts Mountains allochthon, (2) the Jurassic (˜158 Ma) Goldstrike intrusive complex, which includes the Goldstrike diorite laccolith and abundant dikes and sills, (3) a Cretaceous (112 Ma) granite stock, (4) lavas and intrusions of the Emigrant Pass volcanic field and widespread epizonal plugs and dikes of Eocene (˜40-36 Ma) age that range from rhyolite through basalt, and (5) Miocene (15 Ma) rhyolite lava and tuff. Jurassic and Eocene igneous rocks are by far the most important volumetrically and are spatially associated with nearly all ore deposits of the Carlin trend. This study focuses on the field relations, isotopic dating, and geochemistry of Eocene dikes that intrude sedimentary rocks in many deposits of the Carlin trend, because they are the youngest pre-mineral rocks and have simpler alteration histories than other host rocks. In the Beast, Genesis, Deep Star, Betze-Post, Rodeo-Goldbug, Meikle-Griffin, and Dee-Storm deposits, Eocene dikes are altered, commonly mineralized, and locally constitute ore. Gold-bearing dikes and sedimentary rocks have similar ore mineralogy, including arsenian pyrite, marcasite, and arsenopyrite, with late barite and stibnite. At Beast, as much as half the ore is hosted in a 37.3 Ma rhyolite dike. Post-gold alunite is ˜18.6 Ma. At Meikle and Griffin, porphyritic dacite dikes yield concordant U/Pb zircon and 40Ar/39Ar biotite emplacement ages of ˜39.2 Ma, and illite from the same QSP-altered dacite, with as much 9 ppm Au, yields similar, although imprecise 40Ar/39Ar ages. Thus, gold mineralization at these deposits closely followed emplacement of Eocene dikes. Carlin-type gold deposits in northeastern Nevada have been variously interpreted as partly syngenetic with Paleozoic carbonate rocks, products of Mesozoic contraction and metamorphism with or without significant magmatism, and of Tertiary age and related or

  8. Postcollisional mafic igneous rocks record recycling of noble gases by deep subduction of the continental crust

    Science.gov (United States)

    Dai, Li-Qun; Zheng, Yong-Fei; He, Huai-Yu; Zhao, Zi-Fu

    2016-05-01

    Recycling of noble gases from crustal rocks into the mantle is indicated not only by oceanic basalts and mantle xenoliths, but also by ultrahigh-pressure metamorphic rocks in collisional orogens. It is intriguing whether noble gases in continental crust were recycled into the mantle by deep subduction of the continental crust to mantle depths. Here we firstly report the He, Ne and Ar isotopic compositions of pyroxene from postcollisional mafic igneous rocks in the Dabie orogen, China. The results show that the pyroxene separates from the mafic rocks have low 3He/4He ratios of 0.002 to 1.8 Ra and air-like Ne isotope compositions. Furthermore, the pyroxene exhibits low 40Ar/36Ar ratios of 393.6 to 1599.8, close to those of the air. In combination with whole-rock geochemistry it is found that pyroxene 3He/4He ratios are correlated with whole-rock (La/Yb)N and Sr/Y ratios, εNd(t) values and MgO contents. These observations demonstrate the mass transfer from the deeply subducted continental crust to the overlying mantle wedge, recording the source mixing between the crust-derived melt and the mantle peridotite in the continental subduction zone. A direct addition of the crustal He via crust-derived melt to the mantle leads to the extremely low 3He/4He ratios in the orogenic lithospheric mantle, and the dissolved atmospheric Ar and Ne in the subducted supracrustal rocks results in the air-like Ar and Ne isotope ratios. Therefore, the noble gas isotopic signatures of supracrustal rocks were carried into the mantle by the continental deep subduction to subarc depths and then transferred to the postcollisional mafic igneous rocks via the melt-peridotite reaction at the slab-mantle interface in a continental subduction channel. Our finding firstly establishes the slab-mantle interaction model for recycling of supracrustal noble gases in the continental subduction zone.

  9. A reflection seismic study of the Alnö alkaline and carbonatite igneous complex

    Science.gov (United States)

    Andersson, M.; Malehmir, A.; Dehghannejad, M.; Troll, V. R.; Ask, M.

    2012-04-01

    The Alnö igneous complex in central Sweden is one of the largest (about 5 km by 5 km) of the few well-known alkaline and carbonatite intrusions in the world. It contains a wide variety of lithologies, including alkaline silicate igneous rocks (Ijolite, Nephelinesyenite, and Pyroxenite) and a range of carbonatite dykes with a variable composition (Kresten, 1990). Alnö island is the type locality for Alnöite, a melilite-bearing basic rock that occurs as dykes and contains a complex mineral assemblage with phenocrysts from the deep crust and the upper mantle. Geochronological measurements suggest an age of 553-590 Ma for the main intrusion. The depth extent, dip and dip direction of the carbonatite rocks have been inferred from surface geological mapping, but lack depth-constraints. Our research aims to improve understanding of the intrusion mechanism(s) and the geometry of the Alnö intrusion and through that of alkaline and carbonatite intrusions in general. We have acquired three high-resolution reflection seismic profiles over the main intrusion during winter 2011. Densely sampled surface gravity and magnetic data were also collected along the seismic profiles and on the sea-ice with gravity measurements indicating a strong positive Bouguer anomaly of about 20 mGal over the main intrusion. Petrophysical measurements including compressional- and shear-wave velocities, anisotropy of magnetic susceptibility (AMS), and density data were gathered from oriented samples of representative lithologies. For the seismic data, nearly 400 active channels were employed with a geophone spacing of 10 meters. A mechanical hammer was used for generating the seismic waves and was activated at most geophone positions. Since the acquisition took part in winter, we also extended the profiles out on the sea-ice close to the shore. The geophones were planted in the frozen ground/ice and covered by snow resulting in improved signal-to-noise ratios. The main profile is about 10 km long

  10. Atlantic NAD 83 OCS Planning Areas

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains BOEM Planning Area outlines in ESRI shapefile format for the BOEM Atlantic Region. The old Atlantic Planning Area outlines were changed as of...

  11. The North Atlantic Oscillation in the Atlantic-European SLP*

    OpenAIRE

    GLOWIENKA-HENSE, RITA

    2011-01-01

    An analysis of the signature of the North Atlantic Oscillation (NAO) in the Atlantic-European sea level pressure (SLP) is presented for observed (German Weather Service) and ECMWF T21 model data. The former time series consists of 1881–1984 January to December fields and the latter of 42 monthly fields from 3 permanent January simulations. The NAO is shown to be one of the dominant eigenmodes of SLP for all calendar months. A very similar NAO anomaly pattern is filtered from the T21 model dat...

  12. Atlantic CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    R. Steinfeldt

    2010-01-01

    Full Text Available Water column data of carbon and carbon-relevant parameters have been collected and merged into a new database called CARINA (CARbon IN the Atlantic. In order to provide a consistent data set, all data have been examined for systematic biases and adjusted if necessary (secondary quality control (QC. The CARINA data set is divided into three regions: the Arctic/Nordic Seas, the Atlantic region and the Southern Ocean. Here we present the CFC data for the Atlantic region, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113 as well as carbon tetrachloride (CCl4. The methods applied for the secondary quality control, a crossover analyses, the investigation of CFC ratios in the ocean and the CFC surface saturation are presented. Based on the results, the CFC data of some cruises are adjusted by a certain factor or given a "poor'' quality flag.

  13. Atlantic versus Indo-Pacific influence on Atlantic-European climate

    OpenAIRE

    Pohlmann, Holger; Latif, Mojib

    2005-01-01

    The influence of the Atlantic and Indo-Pacific oceans on Atlantic-European climate is investigated by analyzing ensemble integrations with the atmospheric general circulation model ECHAM4 forced by anomalous sea surface temperature and sea ice conditions restricted to the Atlantic (AOGA) and Indo-Pacific (I+POGA) oceans. The forcing from both the Indo-Pacific and Atlantic oceans are important for the generation of the sea level pressure (SLP) variability in the Atlantic region in the boreal w...

  14. Late Miocene biogeography and paleoclimatology of the central North Atlantic

    Science.gov (United States)

    Poore, R.Z.

    1981-01-01

    Quantitative analyses of planktonic foraminiferal assemblages from Deep Sea Drilling Project (DSDP) Holes 334 and 410 demonstrate that subpolar and subtropical faunal provinces existed in the North Atlantic during the late Miocene. Climatic oscillations are clearly recorded in Hole 410 by variations in abundance of the Neogloboquadrina subpolar assemblage. These climatic oscillations have a period of about 1 m.y. Higher frequency oscillations with a periodicity of one to several hundred thousand years are evident from about 6.5 to 7.5 m.y. and are probably present throughout the entire late Miocene. A revised age of 7.0 m.y. is proposed for the first occurrence of the calcareous nannofossil Amaurolithus primus (the Amaurolithus datum). ?? 1981.

  15. Radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico with annotated bibliography. [Over 600 citations

    Energy Technology Data Exchange (ETDEWEB)

    McLemore, V. T.

    1982-01-01

    From an extensive literature search and field examination of 96 nonsandstone radioactive occurrences, the author compiled an annotated bibliography of over 600 citations and a list of 327 radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico. The citations are indexed by individual radioactive occurrence, geographic area, county, fluorspar deposits and occurrences, geochemical analyses, and geologic maps. In addition, the geology, mineralization, and uranium and thorium potential of 41 geographic areas in New Mexico containing known radioactive occurrences in veins and igneous and metamorphic rocks or that contain host rocks considered favorable for uranium or thorium mineralization are summarized. A list of aerial-radiometric, magnetic, hydrogeochemical, and stream-sediment survey reports is included.

  16. Some aspects of the disposal of high level radioactive waste in crystalline, igneous and metamorphic rocks

    International Nuclear Information System (INIS)

    The problems involved in the disposal of high level radio-active wastes in crystalline rocks are considered in terms of the thermomechanical, geochemical and hydrogeological constraints. At present there do not appear to be any fundamental, geological or mechanical reasons why disposal of these wastes in rocks such as granite, gneisses or basic igneous bodies should not be considered as a feasible option. However, tests to determine the mechanical and thermal properties of the rocks under different geological environments are needed to provide information for the conceptual engineering design of a repository. Research is now being done to provide more information in the following fields: on the effects of thermal loading on underground excavations, on the hydrogeology of rocks with low permeabilities on the long-term geochemical and mineralogical response to heating of a body of rock and on the way in which the rock structure affects the rate of migration of any radionuclides which may be released. The present UK research programme is discussed in relation to the variables mentioned above. (Auth.)

  17. Igneous cooling history of olivine-phyric shergottite Yamato 980459 constrained by dynamic crystallization experiments

    Science.gov (United States)

    First, Emily; Hammer, Julia

    2016-07-01

    Dynamic crystallization experiments were performed on a liquid having the bulk composition of olivine-phyric shergottite Yamato 980459, to constrain the igneous thermal history of this meteorite. Key characteristics of the meteorite's mineralogy and texture, including several morphologically distinct olivine and pyroxene crystal populations and a glassy mesostasis devoid of plagioclase, were replicated upon cooling from 1435 to 909 °C at 1 atmosphere under reducing conditions. Three sequential cooling ramps are required to produce synthetic samples with textures and compositions matching Yamato 980459. Olivine phenocrysts formed at stage suppressed the formation of plagioclase and produced groundmass crystals, consistent with crystallization at lava flow depths of 5-7 cm. Although Y 980459 is unique among Martian meteorites (i.e., preserving a primary glassy mesostasis), its emplacement did not require unique physical conditions. Rather, the second and third cooling stages may reflect cooling within the core of a pāhoehoe-like flow and subsequent breakout on the surface of Mars.

  18. Late neoproterozoic igneous complexes of the western Baikal-Muya Belt: Formation stages

    Science.gov (United States)

    Fedotova, A. A.; Razumovskiy, A. A.; Khain, E. V.; Anosova, M. O.; Orlova, A. V.

    2014-07-01

    The paper presents new geological, geochemical, and isotopic data on igneous rocks from a thoroughly studied area in the western Baikal-Muya Belt, which is a representative segment of the Neoproterozoic framework of the Siberian Craton. Three rock associations are distinguished in the studied area: granulite-enderbite-charnockite and ultramafic-mafic complexes followed by the latest tonalite-plagiogranitegranite series corresponding to adakite in geochemical characteristics. Tonalites and granites intrude the metamorphic and gabbroic rocks of the Tonky Mys Point, as well as Slyudyanka and Kurlinka intrusions. The tonalites yielded a U-Pb zircon age of 595 ± 5 Ma. The geochronological and geological information indicate that no later than a few tens of Ma after granulite formation they were transferred to the upper lithosphere level. The Sm-Nd isotopic data show that juvenile material occurs in rocks of granitoid series (ɛNd(t) = 3.2-7.1). Ophiolites, island-arc series, eclogites, and molasse sequences have been reviewed as indicators of Neoproterozoic geodynamic settings that existed in the Baikal-Muya Belt. The implications of spatially associated granulites and ultramafic-mafic intrusions, as well as granitoids with adakitic geochemical characteristics for paleogeodynamic reconstructions of the western Baikal-Muya Belt, are discussed together with other structural elements of the Central Asian Belt adjoining the Siberian Platform in the south.

  19. U-Pb zircon geochronology and evolution of some Adirondack meta-igneous rocks

    Science.gov (United States)

    Mclelland, J. M.

    1988-01-01

    An update was presented of the recent U-Pb isotope geochronology and models for evolution of some of the meta-igneous rocks of the Adirondacks, New York. Uranium-lead zircon data from charnockites and mangerites and on baddeleyite from anorthosite suggest that the emplacement of these rocks into a stable crust took place in the range 1160 to 1130 Ma. Granulite facies metamorphism was approximately 1050 Ma as indicated by metamorphic zircon and sphene ages of the anorthosite and by development of magmatitic alaskitic gneiss. The concentric isotherms that are observed in this area are due to later doming. However, an older contact metamorphic aureole associated with anorthosite intrusion is observed where wollastonite develops in metacarbonates. Zenoliths found in the anorthosite indicate a metamorphic event prior to anorthosite emplacement. The most probable mechanism for anorthosite genesis is thought to be ponding of gabbroic magmas at the Moho. The emplacement of the anorogenic anorthosite-mangerite-charnockite suite was apparently bracketed by compressional orogenies.

  20. Finding of Neoproterozoic low-18O igneous rocks in the northern margin of the Dabie orogen

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yongfei; WU Yuanbao; ZHAO Zifu; GONG Bing

    2004-01-01

    @@ It has been one of the most intriguing questions in the earth sciences whether the snowball Earth event is genetically associated with mantle superwelling, supercontinent assemblage and breakup, and rift magmatism during the Neoproterozoic[1-4]. In order to demonstrate the occurrence of significant interaction in energy and matter between the earth's interior and exterior in this period, it is critical to find coeval igneous rocks that contain the signature of surface water and thus form low-18O magma.Several investigations of U-Pb dating and O isotope analysis were carried out for zircons from ultrahigh pressure (UHP) metamorphic rocks in the Dabie-Sulu orogen,east-central China[5-8]. The results indicate that low δ18O zircons have U-Pb ages of 700-800 Ma as dated by either TIMS discordia upper-intercept or SIMS in-situ magmatic core, and the origin of low δ18O water is related to cold paleoclimate during the Sturtian ice age.

  1. Effects of Igneous Intrusion on Microporosity and Gas Adsorption Capacity of Coals in the Haizi Mine, China

    OpenAIRE

    Jingyu Jiang; Yuanping Cheng

    2014-01-01

    This paper describes the effects of igneous intrusions on pore structure and adsorption capacity of the Permian coals in the Huaibei Coalfield, China. Twelve coal samples were obtained at different distances from a ~120 m extremely thick sill. Comparisons were made between unaltered and heat-affected coals using geochemical data, pore-fracture characteristics, and adsorption properties. Thermal alteration occurs down to ~1.3 × sill thickness. Approaching the sill, the vitrinite reflectance (R...

  2. Study on radon exhalation rate in sedimentary and igneous rocks used as building materials in Tiruchirappalli district, Tamil Nadu, India

    International Nuclear Information System (INIS)

    Tiruchirappalli district is naturally endowed with rich building material resources which are also used in neighboring districts. Hence, measurement of radon level in these building materials is important to assess its impact on human health. The present study was undertaken to measure the activity concentration of radon in 8 sedimentary rock (stone rock) quarries and 6 igneous rocks (granite) quarries. Sealed Can Technique using Solid State Nuclear Track Detector was employed for the measurement of radon emanation. The activity concentration of radon in sedimentary rocks ranged from 18.8 ± 0.3 Bqm-3 to 56.0± 4.8 Bqm-3 with the mean concentration of 29.47 ± 12.6 Bqm-3. However, radon concentrations in igneous rocks are distinctly higher and ranged from 47.8 ± 4.0 Bqm-3 to 570.0 ± 95.0 Bqm-3 with the mean value of 273.5 ± 167.7 Bqm-3. The mean radium concentration (CRa) was recorded in both sedimentary (2.13 ± 0.94 Bqkg-1) and igneous rocks (20.4 ± 12.59 Bqkg-1) were well within the limit prescribed for dwellings (370 Bq kg-1). The mass and surface exhalation rates were also calculated in all the rock samples. The study concludes that the sedimentary rocks and the igneous rocks analyzed were radiologically safe when used as building materials expect the granite rock from Narthamalai (S13) which registers a higher mean radon activity of 570.0 ± 95.0 Bq m-3. (author)

  3. Kilometre-scale sand injectites in the intracratonic Murzuq Basin (South-west Libya): an igneous trigger?

    DEFF Research Database (Denmark)

    Moreau, Julien; Ghienne, Jean-Francois; Hurst, Andrew

    2012-01-01

    sand injection in the form of pipes occurred during the Devonian. The overpressures triggering the process are inferred to result from a combination of: (i) tectonic uplift at a basin scale that initially focused regional ground water flows; and (ii) igneous intrusion within the sand-rich Cambrian...... are often identified in seismic reflection data. Large-scale sand injections might be essential in petroleum exploration of the North African Lower Palaeozoic basins as they form seal-bypass systems....

  4. The Gyrinidae (Coleoptera of the Maritime Provinces of Canada: new records, distribution, and faunal composition

    Directory of Open Access Journals (Sweden)

    Christopher Majka

    2009-09-01

    Full Text Available The Gyrinidae (whirligig beetles of the Maritime Provinces of Canada are surveyed. Twenty-two species are now known to occur in the region, 19 of which have been recorded from Nova Scotia, 17 from New Brunswick, and 9 from Prince Edward Island. Seven species are newly recorded in Nova Scotia, and four in New Brunswick. Two of these, Gyrinus dichrous LeConte and Gyrinus gehringi Chamberlain, are newly recorded in the Maritime Provinces. The zoogeographic composition of the fauna within the region is briefly examined, the species falling into six categories. Islands portions of Atlantic Canada (Prince Edward Island, Cape Breton, and insular Newfoundland have a diminished fauna, roughly 40% that of neighbouring mainland areas. The proportionate composition of the gyrinid fauna in various portions of Atlantic Canada is similar to that of the Carabidae (a much larger suite of beetles that have been more extensively investigated with the exception of New Brunswick, where a diminished number of recorded gyrinids would appear to indicate an insufficient collecting effort for this family in the province. Finally, a preliminary examination of multispecies associations is presented which indicates that some species more frequently engage in such aggregations than others.

  5. A short note on the biogeographic patterns of the Chaetognatha fauna in the North Atlantic

    Science.gov (United States)

    Pierrot-Bults, A. C.

    2008-01-01

    Three different hydrographic regimes were identified during the MAR-ECO cruise in the North Atlantic in June 2004 between 59°N and 42°N. Chaetognaths were sampled with a non-quantitative open plankton net through the entire water column. The species composition of the chaetognaths differed between the Sub-Arctic Province (SAP) and the Cold Temperate Province (CTP), and a frontal region. In the SAP with Sub-Arctic Intermediate Water six species were found, and the species composition was dominated by three species: two of the genus Eukrohnia and one of the genus Sagitta making up 83% of the total number of specimens. In the samples from the CTP with North Atlantic Central Water 16 species were present and here five to six species made up 83% of the total number of specimens. There were no differences between the chaetognath assemblages on either side of the Mid-Atlantic Ridge. Greatest abundances were found at station 18 just northwest of the Charlie-Gibbs Fracture Zone.

  6. Petrography, geochemistry, and geochronology of the Cenozoic Cape Crossfire, Cape King, and No Ridge igneous complexes (northern Victoria Land, Antarctica)

    International Nuclear Information System (INIS)

    The Meander Intrusive Group is the plutonic-subvolcanic counterpart of the McMurdo Volcanic Group, and extends along 200 km of the Ross Sea coast of Northern Victoria Land. The three largest occurrences of the Meander Intrusive Group between the Icebreaker and Borchgrevink glaciers are the Cape Crossfire, the No Ridge, and the Cape King igneous complexes. These have an area of 40-80 square km and are composed of dominant monzogabbros and monzodiorites along with minor syenites and alkali feldspar microgranites. A significant compositional gap exists between mafic and felsic facies, which show geometrical relationships varying from subhorizontal alternating layers to complex pillowing and fragmentation of the mafic into the felsic facies. Two whole rock biotite Rb-Sr internal isochrons constrain the cooling age of Cape Crossfire Igneous Complex at 31 Ma, a few million years older than No Ridge and Cape King igneous complexes. Thus, the ages of these complexes (≤ 31 Ma) are younger than the plutons and dikes (≥ 35 Ma) cropping out in the southernmost area between the Campbell and Icebreaker glaciers. (author). 28 refs., 8 figs., 3 tabs

  7. PHASS99: A software program for retrieving and decoding the radiometric ages of igneous rocks from the international database IGBADAT

    Science.gov (United States)

    Al-Mishwat, Ali T.

    2016-05-01

    PHASS99 is a FORTRAN program designed to retrieve and decode radiometric and other physical age information of igneous rocks contained in the international database IGBADAT (Igneous Base Data File). In the database, ages are stored in a proprietary format using mnemonic representations. The program can handle up to 99 ages in an igneous rock specimen and caters to forty radiometric age systems. The radiometric age alphanumeric strings assigned to each specimen description in the database consist of four components: the numeric age and its exponential modifier, a four-character mnemonic method identification, a two-character mnemonic name of analysed material, and the reference number in the rock group bibliography vector. For each specimen, the program searches for radiometric age strings, extracts them, parses them, decodes the different age components, and converts them to high-level English equivalents. IGBADAT and similarly-structured files are used for input. The output includes three files: a flat raw ASCII text file containing retrieved radiometric age information, a generic spreadsheet-compatible file for data import to spreadsheets, and an error file. PHASS99 builds on the old program TSTPHA (Test Physical Age) decoder program and expands greatly its capabilities. PHASS99 is simple, user friendly, fast, efficient, and does not require users to have knowledge of programing.

  8. Classification oceanique non dirigee des provinces biogeochimiques de l'Atlantique Nord par teledetection

    Science.gov (United States)

    Courtemanche, Bruno

    Mapping bioregions of the oceans is of key importance for a better understanding the dynamics of ecosystems in oceans and ensure the adequate management of them. Actual existing classifications use the same combinations of attributes including: bathymetry, sea surface temperature, chlorophyll concentration and certain standard luminance (443 nm, 520 nm 550 nm). The use of second order variability of optical signals from chlorophyll a suggest other possible global attributes, independent of chlorophyll a concentration, opening doors to new approaches in unsupervised classification of oceans biogechimical provinces. The objective of the study is to develop a method of ocean provinces dynamic unsupervised classification, using a combination of satellite data as : optical signatures of biochemical constituents in the ocean and the physical properties of water masses according to a new approach that integrates both information complementary and independent of chlorophyll a. The goal is to perform the classification of oceanic provinces of the North Atlantic for the availability period of MODIS Aqua (2002-2012) and to determine the spatial evolution of oceanic provinces and their succession over time. Different techniques of classification were carried out on two data sets developed for the purposes of the study. The results show that the K-mean and DBSCAN method are not appropriate to perform bio-optical provinces dynamic classification of the North Atlantic. A new method of classification: PRODENCAN was developed to fill the gaps of these techniques. The results obtained by this method can confirm the potential to improve the classification by the use of second order variability of chlorophyll a optical signals but have not yet led to the creation of a dynamic pattern classification for North Atlantic. Nevertheless, they allow to specify the process for solving this problem by implementing a set of specifically training data spatially and temporally chosen. Dynamic

  9. Monitoring the North Atlantic using ocean colour data

    Science.gov (United States)

    Fuentes-Yaco, C.; Caverhill, C.; Maass, H.; Porter, C.; White, GN, III

    2016-04-01

    The Remote Sensing Unit (RSU) at the Bedford Institute of Oceanography (BIO) has been monitoring the North Atlantic using ocean colour products for decades. Optical sensors used include CZCS, POLDER, SeaWiFS, MODIS/Aqua and MERIS. The monitoring area is defined by the Atlantic Zone Monitoring Program (AZMP) but certain products extend into Arctic waters, and all-Canadian waters which include the Pacific coast. RSU provides Level 3 images for various products in several formats and a range of temporal and spatial resolutions. Basic statistics for pre-defined areas of interest are compiled for each product. Climatologies and anomaly maps are also routinely produced, and custom products are delivered by request. RSU is involved in the generation of Level 4 products, such as characterizing the phenology of spring and fall phytoplankton blooms, computing primary production, using ocean colour to aid in EBSA (Ecologically and Biologically Significant Area) definition and developing habitat suitability maps. Upcoming operational products include maps of diatom distribution, biogeochemical province boundaries, and products from sensors such as VIIRS (Visible Infrared Imaging Radiometer Suite), OLCI (Ocean Land Colour Instrument), and PACE (Pre-Aerosol, Clouds and ocean Ecosystem) hyperspectral microsatellite mission.

  10. Atlantic petroleum royalties : fair deal or raw deal

    International Nuclear Information System (INIS)

    A study was conducted to address the controversy regarding the Newfoundland and Nova Scotia offshore royalty regimes and associated agreements. This study compared the regimes in Atlantic Canada with the best practices elsewhere and laid important groundwork for understanding the Atlantic offshore oil and gas industry. The main concern by the public is whether the distribution of returns from resource exploitation is fair. The report is divided into 6 sections which examine the nature of economic rent in the context of natural resources, and look at various instruments used to lay claim to it. A review of the resource rent royalty (RRR) instrument, dealing with a tax on net cash flow before outlining its approximation by the RRR was included along with a set of examples of such regimes in Australia, Canadian Frontier Lands, and the United Kingdom. An evaluation criteria was developed for the royalty regime and this criteria was applied to the current generic Nova Scotia and Newfoundland offshore petroleum tax regimes. It was concluded that there is room for improvement, but in general, the regimes stand up to rigorous experimentation and they provide a fair return to the provinces and citizens. The present regimes do not discourage further development of the industry. 17 refs., 1 tab., 2 figs

  11. Geochemical characteristics and zircon U-Pb isotopic ages of island-arc basic igneous complexes from the Tianshui area in West Qinling

    Institute of Scientific and Technical Information of China (English)

    PEI Xianzhi; LI Zuochen; LIU Huibin; LI Gaoyang; DING Saping; LI Yong; HU Bo; GUO Junfeng

    2007-01-01

    The Liushuigou intermediate-basic meta-igneous complex at Guanzizhen, Tianshui area, is mainly composed of metagabbro, metagabbro diorite and metadiorite, while the Baihua basic meta-igneous complex consists mainly of pyroxenite, gabbro (gabbro diorite), diorite and quartz diorite.They form a relatively complete comagmatic evolutionary series. The geochemical characteristics of intermediate-basic igneous rocks indicate that they belong to a tholeiite suite.Their chondrite-normalized REE patterns are nearly flat and are LREE-slightly enriched type, and their primitive mantle-normalized and MORB-normalized trace element spider-grams are generally similar; the LILEs Cs, Ba, Sr, Th and U are enriched, while Rb and K and the HFSEs Nb, P, Zr,Sm, Ti and Y are depleted. All these show comagmatic evolu-tionary and genetic characteristics. The tectonic environment discrimination by trace element reveals that these igneous complexes formed in an island-arc setting. The Thermal Ionization Mass Spectrometry (TIMS) single-grain zircon U-Pb age for the Liushuigou intermediate-basic meta-igneous rocks in the Guanzizhen area is (507.5 ± 3.0) Ma, represent-ing the age of these igneous complexes, which indicates that island-arc-type magmatite rocks in the northern zone of West Qinling are Late Cambrian and also reveals that the timing of subduction of the paleo-ocean basin represented by the Guanzizhen ophiolite and resulting island-arc-type magrnaticactivity are probably Late Cambrian to Early Ordovician.

  12. Strategy of converting Jiangsu Province A Foreign-trade Large Province into A Foreign-trade Strong Province

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ Jiangsu Province, after executing economic internationalization strategy and establishing the strategic goal of foreign-trade strong province,meaning to pursue a dominating position in the foreign trade relations, has become one of the foreign-trade large provinces of China and provided considerable international competitive power in some important fields.

  13. Strategy of converting Jiangsu Province A Foreign-trade Large Province into A Foreign-trade Strong Province

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

      Jiangsu Province, after executing economic internationalization strategy and establishing the strategic goal of foreign-trade strong province,meaning to pursue a dominating position in the foreign trade relations, has become one of the foreign-trade large provinces of China and provided considerable international competitive power in some important fields.……

  14. The Paleoproterozoic Singo granite in south-central Uganda revealed as a nested igneous ring complex using geophysical data

    Science.gov (United States)

    Abdelsalam, Mohamed G.; Katumwehe, Andrew B.; Atekwana, Estella A.; Le Pera, Alan K.; Achang, Mercy

    2016-04-01

    We used high-resolution airborne magnetic and radiometric data and satellite gravity data to investigate the form of occurrence of the Paleoproterozoic Singo granite in west-central Uganda. This granitic body covers an area of ∼700 km2, intrudes Paleoproterozoic crystalline rocks and overlain by Paleoproterozoic-Mesoproterozoic sedimentary rocks, both of which belong to the Rwenzori terrane, and it is host to hydrothermally-formed economic minerals such as gold and tungsten. Our analysis provided unprecedented geometrical details of the granitic body and revealed the following: (1) the margins of the Singo granite are characterized by a higher magnetic signature compared to the interior of the granitic body as well as the surroundings. These anomalies are apparent in both the total magnetic field and horizontal derivative images and define eight overlapping ring features. (2) the depth continuation of these magnetic anomalies define outward but steeply-dipping features as indicated by the tilt images extracted from the airborne magnetic data. This is further supported by forward modeling of the magnetic and gravity data. (3) the Singo granite is characterized by relatively high and evenly-distributed equivalent concentration of Uranium (eU) and Thorium (eTh) compared to the surroundings and this is apparent in the Potassium (K)-eTh-eU radiometric ternary image. (4) the granitic body is defined by a gravity low anomaly that persisted to a depth of three km as shown by the Bouguer anomaly image and its five km upward continuation. We used these observations to identify this granitic body as a nested igneous ring complex and we refer to it as the Singo Igneous Ring Complex (SIRC). We further interpreted the eight ring structures as individual igneous ring complexes aligned in an E-W and NE-SW direction and these were developed due to repeated calderas collapse. Additionally, we interpreted the ring-shaped magnetic anomalies as due to hydrothermally-altered margins

  15. Fjve Ways to Revive Liaoning Province

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Construction of development zones along the Liaoning Province coastline could be the next big attraction for multinational investors Though the infrastructure is still under construction, Li Wancai, Vice Governor of Liaoning Province, is highly confident about the future of

  16. Marketing and Aquaculture Sector in Antalya Province

    OpenAIRE

    Gümüş*(2), Erkan; YILMAZ, Serpil

    2011-01-01

    In Turkey, the aquaculture sector that is rapid progress has also become an important sector for Antalya province as in other provinces in recent years. Antalya Province have an important potential both marine and inland water for aquaculture. However, it is not possible to talk about this potential can be used effectively because of an important tourist resort of Antalya Province. Nevertheless, a total of 5482 tons / year capacity has been operating 86 license...

  17. Research on Population Prediction of Guizhou Province

    Institute of Scientific and Technical Information of China (English)

    Shuang; YU; Guang; LI

    2013-01-01

    In accordance with population development of Guizhou Province in 1977-2007,this paper adopts natural growth method,model prediction method and gray system GM (1,1) model prediction method to predict population of Guizhou Province in 2020. On the basis of overall consideration of many factors of population development and future development trend of Guizhou Province,it analyzes advantages and disadvantages of three prediction methods,and obtains the prediction value of total population of Guizhou Province in 2020.

  18. Environmental controls on the biogeography of diazotrophy and Trichodesmium in the Atlantic Ocean

    Science.gov (United States)

    Snow, J. T.; Schlosser, C.; Woodward, E. M. S.; Mills, M. M.; Achterberg, E. P.; Mahaffey, C.; Bibby, T. S.; Moore, C. M.

    2015-06-01

    The cyanobacterium Trichodesmium is responsible for a significant proportion of the annual "new" nitrogen introduced into the global ocean. Despite being arguably the best studied marine diazotroph, the factors controlling the distribution and growth of Trichodesmium remain a subject of debate, with sea surface temperature, the partial pressure of CO2, and nutrients including iron (Fe) and phosphorus (P), all suggested to be important. Synthesizing data from seven cruises collectively spanning large temporal and spatial scales across the Atlantic Ocean, including two previously unreported studies crossing the largely undersampled South Atlantic gyre, we assessed the relationship between proposed environmental drivers and both community N2 fixation rates and the distribution of Trichodesmium. Simple linear regression analysis would suggest no relationship between any of the sampled environmental variables and N2 fixation rates. However, considering the concentrations of iron and phosphorus together within a simplified resource-ratio framework, illustrated using an idealized numerical model, indicates the combined effects these nutrients have on Trichodesmium and broader diazotroph biogeography, alongside the reciprocal maintenance of different biogeographic provinces of the (sub)tropical Atlantic in states of Fe or P oligotrophy by diazotrophy. The qualitative principles of the resource-ratio framework are argued to be consistent with both the previously described North-South Atlantic contrast in Trichodesmium abundance and the presence and consequence of a substantial non-Trichodesmium diazotrophic community in the western South Atlantic subtropical gyre. A comprehensive, observation-based explanation of the interactions between Trichodesmium and the wider diazotrophic community with iron and phosphorus in the Atlantic Ocean is thus revealed.

  19. Prospecting for Diverse Igneous Rock Types on Mars: Pixl on "black Beauty" Nwa 7533

    Science.gov (United States)

    Liu, Y.; Flannery, D.; Allwood, A.; Thompson, D. R.; Hodyss, R. P.; Clark, B. C.; Elam, W. T.; Hurowitz, J.

    2015-12-01

    In order to understand the evolution of the Martian crust and mantle, we need to acquire and analyze samples of igneous rocks other than the basaltic and ultramafic lithologies represented by the majority of Martian meteorites. Recent results from the Curiosity Rover demonstrate that diverse rock types exist in some Martian sedimentary environments in the form of conglomerate components or float, some of which shed light on the nature of early Martian crust (e.g., Sautter et al., 2015). We are developing investigation strategies for the in-situ instruments that will be flown on the Mars 2020 rover. These instruments will be used to inform the sampling campaigns required for future sample return missions. To achieve this, we applied PIXL (Planetary Instrument for X-ray Lithochemistry), an instrument for the Mars 2020 rover mission, to the meteorite NWA 7533. This meteorite is a pairing of NWA 7034, known informally as "Black Beauty", a new type of Martian meteorite that is broadly similar to the average composition of the Martian crust. This type of meteorite is essentially a 'conglomerate', with many diverse rock types, including mafic, feldspathic, and exotic rock fragments such as feldspar-ilmenite-phosphate clasts, as observed using higher-spatial resolution and higher sensitivity laboratory instruments (e.g., Agee et al., 2013; Humayun et al., 2014; Santos et al., 2015). Using PIXL, we analyzed a mm-scale cut and polished surface and applied algorithms developed by the PIXL team to semi-autonomously define and group regions containing similar lithological components (Thompson et al., 2015). PIXL data rapidly reveal distinctive zircon-bearing lithologies and feldspar-ilmenite-phosphate clasts similar to the detailed petrographic and mineralogical observations. Results suggest that PIXL readily identifies lithologies with minerals and elements (e.g., Rb and Sr) that are important for geochronology studies.

  20. Alkaline igneous rocks of Magnet Cove, Arkansas: Mineralogy and geochemistry of syenites

    Science.gov (United States)

    Flohr, M.J.K.; Ross, M.

    1990-01-01

    Syenites from the Magnet Cove alkaline igneous complex form a diverse mineralogical and geochemical suite. Compositional zoning in primary and late-stage minerals indicates complex, multi-stage crystallization and replacement histories. Residual magmatic fluids, rich in F, Cl, CO2 and H2O, reacted with primary minerals to form complex intergrowths of minerals such as rinkite, fluorite, V-bearing magnetite, F-bearing garnet and aegirine. Abundant sodalite and natrolite formed in pegmatitic segregations within nepheline syenite where Cl- and Na-rich fluids were trapped. During autometasomatism compatible elements such as Mn, Ti, V and Zr were redistributed on a local scale and concentrated in late-stage minerals. Early crystallization of apatite and perovskite controlled the compatible behavior of P and Ti, respectively. The formation of melanite garnet also affected the behaviour of Ti, as well as Zr, Hf and the heavy rare-earth elements. Pseudoleucite syenite and garnet-nepheline syenite differentiated along separate trends, but the two groups are related to the same parental magma by early fractionation of leucite, the presumed precursor of intergrowths of K-feldspar and nepheline. The Diamond Jo nepheline syenite group defines a different differentiation trend. Sphene-nepheline syenite, alkali syenite and several miscellaneous nepheline syenites do not consistently plot with the other syenite groups or each other on element and oxide variation diagrams, indicating that they were derived from still other parental syenite magmas. Mineral assemblages indicate that relatively high f{hook};O2, at or above the fayalite-magnetite-quartz buffer, prevailed throughout the crystallization history of the syenites. ?? 1990.

  1. Factors influencing particulate lipid production in the East Atlantic Ocean

    Science.gov (United States)

    Gašparović, B.; Frka, S.; Koch, B. P.; Zhu, Z. Y.; Bracher, A.; Lechtenfeld, O. J.; Neogi, S. B.; Lara, R. J.; Kattner, G.

    2014-07-01

    Extensive analyses of particulate lipids and lipid classes were conducted to gain insight into lipid production and related factors along the biogeochemical provinces of the Eastern Atlantic Ocean. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a), phaeopigments, Chl a concentrations and carbon content of eukaryotic micro-, nano- and picophytoplankton, including cell abundances for the latter two and for cyanobacteria and prokaryotic heterotrophs. We focused on the productive ocean surface (2 m depth and deep Chl a maximum (DCM). Samples from the deep ocean provided information about the relative reactivity and preservation potential of particular lipid classes. Surface and DCM particulate lipid concentrations (3.5-29.4 μg L-1) were higher than in samples from deep waters (3.2-9.3 μg L-1) where an increased contribution to the POC pool was observed. The highest lipid concentrations were measured in high latitude temperate waters and in the North Atlantic Tropical Gyral Province (13-25°N). Factors responsible for the enhanced lipid synthesis in the eastern Atlantic appeared to be phytoplankton size (micro, nano, pico) and the low nutrient status with microphytoplankton having the most expressed influence in the surface and eukaryotic nano- and picophytoplankton in the DCM layer. Higher lipid to Chl a ratios suggest enhanced lipid biosynthesis in the nutrient poorer regions. The various lipid classes pointed to possible mechanisms of phytoplankton adaptation to the nutritional conditions. Thus, it is likely that adaptation comprises the replacement of membrane phospholipids by non-phosphorus containing glycolipids under low phosphorus conditions. The qualitative and quantitative lipid compositions revealed that phospholipids were the most degradable lipids, and their occurrence decreased with increasing depth. In contrast, wax esters, possibly originating from zooplankton, survived downward transport probably due to the fast sinking

  2. Rocas Verdes Ophiolite Complexes in the Southernmost Andes: Remnants of the Mafic Igneous Floor of a Back-arc Basin that Rifted the South American Continental Crust in the Late Jurrassic and Early Cretaceous

    Science.gov (United States)

    Stern, C. R.

    2001-12-01

    The Rocas Verdes are an en echelon group of late Jurassic and early Cretaceous igneous complexes in the southernmost Andes. They consist of mafic pillow lavas, dikes and gabbros interpreted as the upper portions of ophiolite complexes formed along mid-ocean-ridge-type spreading centers. When secondary metamorphic affects are accounted for, the geochemistry of mafic Rocas Verdes rocks are similar to ocean-ridge basalts (MORB). The spreading centers that generated the Rocas Verdes rifted the southwestern margin of the Gondwana continental crust, during the start of break-up in the southern Atlantic, to form the igneous floor of a back-arc basin behind a contemporaneous convergent plate boundary magmatic arc. Late Jurassic and early Cretaceous sediments from both the magmatic arc on the southwest and the continental platform on the northeast of the basin were deposited in the Rocas Verdes basin, and these sediments are interbedded with mafic pillow lavas along the margins of the Rocas Verdes mafic complexes. Also, mafic dikes and gabbros intrude older pre-Andean and Andean lithologies along both flanks of the Rocas Verdes, and leucocratic country rocks are engulfed in the Rocas Verdes mafic complexes. These relations indicate that the Rocas Verdes complexes formed in place and are autochthonous, having been uplifted but not obducted, which may explain the lack of exposure of the deeper ultramafic units. Zircon U/Pb ages of 150+/-1 Ma for the Larsen Harbour Formation, a southern extension of the Rocas Verdes belt on South Georgia Island, and 138+/-2 Ma for the Sarmiento complex, the northernmost in the Rocas Verdes belt, indicate that this basin may have formed by "unzipping" from the south to the north, with the southern portion beginning to form earlier and developing more extensively than the northern portion of the basin. Paleomagnetic data suggest that the Rocas Verdes basin developed in conjunction with the displacement of the Antarctic Peninsula and opening of

  3. Sheeting, Mingling, and Up Direction?, Hortavaer Igneous Complex, North-central Norway

    Science.gov (United States)

    McCulloch, L. E.; Barnes, C. G.; Prestvik, T.

    2005-12-01

    The c. 456 Ma Hortavaer igneous complex intrudes quartzofeldspathic gneiss, quartzite, marble and calc-silicate gneiss of the Helgeland Nappe Complex of the Uppermost Allochthon. The intrusive rocks may be divided into at least three distinct zones, each of which contains screens/xenoliths of the host rocks. The western "syenitic zone" is predominantly fine- to very coarse-grained syenite. Grain size is variable on the outcrop scale, primarily due to intrusion and mingling of fine-grained syenite in coarser grained syenite. The eastern "dioritic zone" consists of hundreds of mafic sheet-like intrusions (gabbro to monzodiorite), metasomatized calc-silicate rocks (now melanocratic syenite and monzonite), monzonite, and syenite. Cross-cutting relationships, particularly back-veining of syenite in mafic bodies, indicate that syenitic magmas were present throughout emplacement of the mafic magmas. The boundary between syenitic and dioritic zones consists of parallel to subparallel syenite and diorite sheets from cm to c. 10 m wide. The sheets strike N to NE and dip W to NW between 40° and 60°. In this "sheeted zone", possible hybrid rocks are identified by their intermediate color index, their occurrence as enclaves within syenite and diorite, and locally by the presence of syenitic and dioritic enclaves in intermediate rocks. Contacts between sheeted zone syenite and diorite are asymmetric. The western contacts of many diorite sheets are chilled against syenite and locally show flame- and load cast- like structures. In contrast, the eastern contacts range from planar to wispy or crenulate, and dioritic enclaves are common. If this asymmetry is used as a geopetal indicator, then original up direction was to the east and the Hortavaer complex is now overturned. The nearby Leka ophiolite underwent block rotation of about 90° to the east; similar, larger eastward block rotation of the Hortavaer complex would result in overturning of the sheets. Reconstruction of the

  4. Igneous History of the Andean Cordillera and Patagonian Plateau around Latitude 46 degrees S

    Science.gov (United States)

    Baker, P. E.; Rea, W. J.; Skarmeta, J.; Caminos, R.; Rex, D. C.

    1981-11-01

    From the Middle Jurassic onwards persistent igneous activity in the southern Andes around 46 degrees S was controlled by easterly dipping subduction along the Pacific margin. Cogenetic plutonic rocks belonging to the Patagonian batholith, and calc-alkaline volcanics ranging from basaltic andesites to rhyolitic tuffs and ignimbrites are the principal products. Erosion of the primary volcanics has led at various times to the development of thick volcaniclastic sequences, for example in the Cretaceous--Lower Tertiary Divisadero formation. The Coyhaique region marks the northerly extension of a narrow back-arc basin in which the marine Neocomian successions accumulated. Volcaniclastics from the island arc, which presumably lay to the west, are intercalated with the sediments. Although the marine basin was short-lived a mildly extensional back-arc regime may have existed through much of Mesozoic--Recent times. Widespread basalt--rhyolite volcanism on the eastern side of the cordillera seems to have been associated with this tectonic environment. Remnants of the Patagonian basalt plateau at latitude 45-47 degrees S extend from the Argentine--Chile frontier to Lago Colhue Huapi. Four principal age and compositional groups have been distinguished in the lavas. (i) The oldest, which are about 80 Ma, occur in sections at Senguerr and Morro Negro. They are almost exclusively tholeiitic, but show some calc-alkaline affinities and resemble in other respects basalts from marginal basins. (ii) The second group (57-43 Ma) occur in the lower part of the Chile Chico section with a compositional spread from olivine tholeiites through alkali basalts to one occurrence of a basanite. (iii) The upper part of the main plateau sequence, where the flows are in the range 25-9 Ma, are dominantly of alkali basalt composition. (iv) Post-plateau flows from small cinder cones on the surface of the plateau range in age from ca. 4 Ma to 0.2 Ma or less. They are mostly highly undersaturated

  5. Helium and argon isotopes of the Tertiary basic igneous rocks from Shandong Peninsula and implications for the magma origin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Helium (He) and Argon (Ar) isotopic compositions of the Tertiary basic igneous rocks were determined by the high temperature melting extraction method. The selected samples for the studies included al-kaline basalts and diabases from the Jiyang basin,and the surrounding Shanwang and Qixia outcrops in the Shandong Peninsula,eastern China. The results show that the Paleogene basalts and diabases from the Jiyang basin yielded a wide range of P4 PHe abundance of (73.70-804.16)×10 P-8 Pcm P3 P STP·g P-1 P,with P3 PHe/ P4 PHe ratios of 0.374-2.959 Ra,which was lower than the MORB but evidently higher than the con-tinental crust value. The Neogene alkaline basalts from the Jiyang basin,Shanwang and Qixia outcrops have variable P4 PHe abundances ((42.34-286.72)×10-8 Pcm P3 P STP·g-1 P),and "continental crust-like" P3 PHe/ P4 PHe ratios (0.013-0.074 Ra). All of them contain atmospheric-like P40 PAr/ P36 PAr ratio (395.4-1312.7),reflecting the mantle sources with air components. Their low P3 PHe/ P4 PHe ratios are interpreted as the enrichment of the radiogenic P4 PHe mainly inherited from the mantle. He and Ar systematics show the mixing of MORB-type,air and a P4 PHe enriched member in the mantle source,suggesting that these igneous rocks originated from the depleted asthenospheric mantle mixed with an EMI component. Therefore,the present He and Ar isotopes do not support the viewpoints that the Cenozoic igneous rocks of Eastern North China were the products of mantle plume(s) activities.

  6. U-Pb circon ages from the Milford Orthogneiss, Milford Sound, northern Fiordland : Paleozoic igneous emplacement and Early Cretaceous metamorphism

    International Nuclear Information System (INIS)

    Milford Orthogneiss is an extensive hornblende-metadiorite/gabbro unit centred on Milford Sound, northern Fiordland. U-Pb TIMS data from zircon indicate both Paleozoic and Early Cretaceous age components, but cannot distinguish between a Palozoic or Early Cretaceous age for the igneous protolith. U-Pb zircon ion probe analyses, guided by cathodoluminescence images of the internal structure of the zircons, indicate that individual grains are either essentially Paleozoic (355 +/-10 Ma oscillaroty zoned igneous grains) or Early Cretaceous (134 +/-2 Ma patchy/sector zoned grains) in age. Rare grains show patchy/'sector' zones apparently overprinting and replacing oscillatory zonation. In most cases both types of grain are also rimmed by low-U zircon (120 +/-2 Ma) that may date the breakdown of a Zr-containing mafic phase during a second phase of prograde metamorphism. Other than the low U-rims, a (igneous) Cretaceous overgrowth over a Paleozoic core is not observed. We interpret these data to indicate that the protolith of the Milford Orthogneiss was emplaced at ∼360 Ma and subsequently metamorphosed in two distinct events in the Early Cretaceous (∼134 and ∼120 Ma. Thus 1) the Milford Orthogneiss cannot represent the metamorphic equivalent of the high-level Darran Complex (138 Ma) to the east, despite lithological and chemical similarities, and a major shear zone is confirmed between these two units; 2) Paleozoic 'cover' rocks in Fiordland may have suffered high-pressure metamorphism in the Cretaceous; 3) annealing or recrystallisation of zircon at ∼134 Ma is believed to record a high-pressure metamorphic event possibly related to subduction of the continental margin; and 4) Milford Orthogneiss may represent McCulloch et al.'s (1987) hypothesised source from which the Western Fiordland Orthogneiss was derived. (author). 36 refs., 9 figs., 2 tabs

  7. Late cretaceous extensional tectonics and associated igneous activity on the northern margin of the Gulf of Mexico Basin

    Science.gov (United States)

    Bowen, R. L.; Sundeen, D. A.

    1985-01-01

    Major, dominantly compressional, orogenic episodes (Taconic, Acadian, Alleghenian) affected eastern North America during the Paleozoic. During the Mesozoic, in contrast, this same region was principally affected by epeirogenic and extensional tectonism; one episode of comparatively more intense tectonic activity involving extensive faulting, uplift, sedimentation, intrusion and effusion produced the Newark Series of eposits and fault block phenomena. This event, termed the Palisades Disturbance, took place during the Late Triassic - Earliest Jurassic. The authors document a comparable extensional tectonic-igneous event occurring during the Late Cretaceous (Early Gulfian; Cenomanian-Santonian) along the southern margin of the cratonic platform from Arkansas to Georgia.

  8. Spectral gamma-ray survey of alkaline igneous complex; Arukari kasei fukugo gantai ni okeru ganma sen supekutoru tansa

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Mitsuo; Karim, T.; Naseer, M. A.

    1999-02-01

    Spectral gamma-ray survey is applied to the investigation of Ambela-Koga-Naranji Kandao igneous complex in Peshawar region in the North of Pakistan located in the northwest edge of the Indian Subcontinent. As a result, quartz syenite-granite, nepheline syenite and phenacite carbonatite rocks respective exhibit gamma-ray spectral anomalies. All the rocks can be identified and characterized easily by gamma-ray spectrums using eU-eTh diagram. Further, on the basis of the obtained gamma-ray spectral anomalies, the evaluation of the storing potential of are earth resources in the same region was attempted. (translated by NEDO)

  9. CARINA oxygen data in the Atlantic Ocean

    OpenAIRE

    Stendardo, I.; Gruber, N.; A. Körtzinger

    2009-01-01

    In the CARINA (Carbon dioxide in the Atlantic Ocean) project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC) procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the c...

  10. Neotectonics in the maritime provinces

    International Nuclear Information System (INIS)

    Seismic risk assessment in the Maritime Provinces requires input from not just historical, but also geological sources. A detailed search through published and unpublished geological literature reveals many examples - some probable, some possible -of neotectonic movement in the area. Examples range in tectonic significance from those that reflect exaggerated local imbalance to those that signify deep-seated stress. Evidence for neotectonism in the Maritimes is multidisciplined. It includes deformation in bedrock and quaternary deposits, and regional warping. Recent movement also is indicated by changes in relative sea level, in situ stress fields and geodetic fluctuations. Finally, and most unequivocally, neotectonism in the Maritime Provinces is manifested as the seismic events that have sporadically affected the area throughout its recent geological history, and continue up to the present day. 288 refs

  11. Earth Science Studies in Support of Public Policy Development and Land Stewardship - Headwaters Province, Idaho and Montana

    Science.gov (United States)

    U.S. Geological Survey Headwaters Province Project Team Edited by Lund, Karen

    2007-01-01

    The USGS Headwaters Province project in western Montana and northern and central Idaho was designed to provide geoscience data and interpretations to Federal Land Management Agencies and to respond to specific concerns of USDA Forest Service Regions 1 and 4. The project has emphasized development of digital geoscience data, GIS analyses, topical studies, and new geologic interpretations. Studies were designed to more completely map lithologic units and determine controls of deformation, magmatism, and mineralizing processes. Topical studies of geologic basement control on these processes include study of regional metallogenic patterns and their relation to the composition and architecture of underlying, unexposed basement; timing of igneous and hydrothermal systems, to identify regionally important metallogenic magmatism; and the geologic setting of Proterozoic strata, to better understand how their sedimentary basins developed and to define the origin of sediment-hosted mineral deposits. Interrelated products of the project are at complementary scales.

  12. 77 FR 69596 - Atlantic Highly Migratory Species; Advisory Panel for Atlantic Highly Migratory Species Southeast...

    Science.gov (United States)

    2012-11-20

    ... but not limited to data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean... assessments for oceanic sharks in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea. While the SEDAR Pool was created specifically for Atlantic oceanic sharks, it may be expanded to include other HMS,...

  13. 76 FR 65700 - Atlantic Highly Migratory Species; Advisory Panel for Atlantic Highly Migratory Species Southeast...

    Science.gov (United States)

    2011-10-24

    ..., used in stock assessments for oceanic sharks in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea... sharks in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea. While the SEDAR Pool was created specifically for Atlantic oceanic sharks, it may be expanded to include other HMS, as needed. The...

  14. 22 CFR 120.31 - North Atlantic Treaty Organization.

    Science.gov (United States)

    2010-04-01

    ... DEFINITIONS § 120.31 North Atlantic Treaty Organization. North Atlantic Treaty Organization (NATO) is..., France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, The Netherlands,...

  15. Geochemistry and petrogenesis of anorogenic basic volcanic-plutonic rocks of the Kundal area, Malani Igneous Suite, western Rajasthan, India

    Indian Academy of Sciences (India)

    A Krishnakanta Singh; G Vallinayagam

    2004-12-01

    The Kundal area of Malani Igneous Suite consists of volcano-plutonic rocks. Basalt flows and gabbro intrusives are associated with rhyolite. Both the basic rocks consist of similar mineralogy of plagioclase, clinopyroxene as essential and Fe-Ti oxides as accessories. Basalt displays sub-ophitic and glomeroporphyritic textures whereas gabbro exhibits sub-ophitic, porphyritic and intergrannu- lar textures. They show comparable chemistry and are enriched in Fe, Ti and incompatible ele- ments as compared to MORB/CFB. Samples are enriched in LREE and slightly depleted HREE patterns with least significant positive Eu anomalies. Petrographical study and petrogenetic mod- eling of [Mg]-[Fe], trace and REE suggest cogenetic origin of these basic rocks and they probably derived from Fe-enriched source with higher Fe/Mg ratio than primitive mantle source. Thus, it is concluded that the basic volcano-plutonic rocks of Kundal area are the result of a low to moderate degree (> 30%) partial melting of source similar to picrite/komatiitic composition. Within plate, anorogenic setting for the basic rocks of Kundal area is suggested, which is in conformity with the similar setting for Malani Igneous Suite.

  16. Chemical weathering on Mars - Thermodynamic stabilities of primary minerals /and their alteration products/ from mafic igneous rocks

    Science.gov (United States)

    Gooding, J. L.

    1978-01-01

    Chemical weathering on Mars is examined theoretically from the standpoint of thermodynamic equilibrium between primary rock-forming minerals and the atmospheric gases O2, H2O, and CO2. The primary minerals considered are those common to mafic igneous rocks and include olivine, pyroxene, plagioclase, magnetite, troilite, pyrrhotite, and apatite. The importance of kinetics and reaction mechanisms in controlling possible weathering processes on Mars is discussed within the limits of currently available data, and the possible influence of liquid water on Martian weathering processes is evaluated where appropriate. For gas-solid weathering of mafic igneous rocks at the Martian surface, it is concluded that upon attainment of thermodynamic equilibrium: (1) oxides and carbonates should dominate the mineral assemblage of weathering products; (2) hematite rather than goethite should be the stable mineral form of Fe (III); (3) FeSO4 or FeSO4.H2O could be the stable weathering product of iron sulfides in the absence of liquid water; and (4) kaolinite is apparently the only clay mineral that should be thermodynamically stable over all ranges of temperature and water-vapor abundance at the Martian surface.

  17. Butalón igneous rocks, Neuquén, Argentina: Age, stratigraphic relationships and geochemical features

    Science.gov (United States)

    Casé, A. M.; López-Escobar, L.; Danieli, J. C.; Schalamuk, A.

    2008-09-01

    Three main groups of igneous rocks of different age are recognized in the Butalón area, including volcanic rocks of the Choiyoi Group (Permian-Triassic), stocks and dikes of the Granodiorita Varvarcó (Upper Cretaceous-Paleocene) and stocks and dikes of the Tonalita Butalón (Paleocene-Eocene?). The Choiyoi Group consists of ignimbrites, breccias, tuffs and silicic lavas. Most are subalkaline and four groups can be distinguished on the basis of their trace element patterns. Most samples are enriched in Ba, but depleted in Nb, Sr, P, Ti and Eu. The subvolcanic rocks of the Granodiorita Varvarcó and Tonalita Butalón are mainly calc-alkaline, metaluminous to peraluminous, with low to medium potassium contents. They have similar subparallel REE and multielement patterns with low La/Yb and Eu/Eu ∗ ratios. These patterns mimic those observed in Pleistocene-Holocene volcanic rocks, of similar SiO 2 content, from the CSVZ of the Andes. They are depleted in Nb and Ti, have normal to low P, and are enriched in Sr and Zr. Hornfels-skarn type hydrothermal alteration is produced by Tonalita Butalón in the adjacent igneous rocks. Magmatic-hydrothermal breccias are developed on top of some of the stocks. While some of the breccias exhibit Mo anomalies, Au and Ag anomalies are present in the Choiyoi Group.

  18. The superior analyses of igneous rocks from Roth's Tabellen, 1869 to 1884, arranged according to the quantitative system of classification

    Science.gov (United States)

    Washington, H.S.

    1904-01-01

    In Professional Paper No. 14 there were collected the chemical analyses of igneous rocks published from 1884 to 1900, inclusive, arranged according to the quantitative system of classification recently proposed by Cross, Iddings, Pirsson, and Washington. In order to supplement this work it has appeared advisable to select the more reliable and complete of the earlier analyses collected by Justus Roth and arrange them also in the same manner for publication. Petrographers would thus have available for use according to the new system almost the entire body of chemical work of real value on igneous rocks, the exceptions being a few analyses published prior to 1900 which may have been overlooked by both Roth and myself. The two collections would form a foundation as broad as possible for future research and discussion. I must express my sense of obligation to the United States Geological Survey for publishing the present collection of analyses, and my thanks to my colleagues in the new system of classification for their friendly advice and assistance. 

  19. Geochronology of hydrothermal uranium deposits and associated igneous rocks in the eastern source area of the Mount Belknap Volcanics, Marysvale, Utah

    International Nuclear Information System (INIS)

    Radiometric ages of igneous rocks and hydrothermal uranium-fluorine veins in the eastern source area of the Mount Belknap Volcanics near Marysvale, Utah, show that igneous activity occurred over a time interval of about 9 million years and that hydrothermal uranium deposits were formed about midway through the interval. Intrusive igneous activity in the central mining area began about 23 m.y. ago with emplacement of the quartz monzonitic central intrusive of the Buillion Canyon Volcanics and was followed by a hypabyssal granitic stock, eruption of the Red Hills Tuff Member, and emplacement of dikes, finally ending about 18 m.y. ago. Hydrothermal uranium mineralization occurred with the last event in this sequence and is genetically associated with emplacement of glassy rhyolite dikes between 18 and 19 m.y. ago. Refs

  20. A Fresh Plutonic Igneous Angrite Containing Grain Boundary Glass From Tamassint, Northwest Africa

    Science.gov (United States)

    Irving, A. J.; Kuehner, S. M.; Rumble, D.

    2006-12-01

    Tamassint Angrite: A small fragmented stone found in June 2006 south of Tamassint oasis in the Morocco-Algeria border region represents a new type of angrite lithology, unlike the coarse grained metamorphic or fine grained "basaltic" to quench-textured examples known previously. This extremely fresh, fusion-crusted specimen has a coarse grained (0.6-12 mm) plutonic igneous cumulate texture, and is composed of Al-Ti-rich clinopyroxene (33.4%), pure anorthite (28.6%), Ca-rich olivine (18.7%) with prominent exsolution lamellae (10-50 μm wide) of kirschsteinite, ulvöspinel (18.5%), and accessory glass, troilite and metal. Subhedral anorthite grains are partially enclosed within larger ulvöspinel grains. Mineral compositions are as follows: clinopyroxene (Fs20.8-33.3Wo53-54.9, Al2O3 = 5.7 to 9.4 wt.%, TiO2 = 0.9 to 2.9 wt.%, FeO/MnO = 85-278), olivine (Fa72.6-74.7Ln3.5-3.6, CaO = 2.1 wt.%, FeO/MnO = 70-87), kirschsteinite (Fa44.7-45.4Ln46-47.2, FeO/MnO = 73-82), ulvöspinel (TiO2 = 27.6 wt.%, Al2O3 = 5.5 wt.%). Reintegration of the kirschsteinite lamellae gives a pre-exsolution olivine composition of Fa68.1Ln12.2 with 7.3 wt.% CaO. Present along grain boundaries (notably between anorthite and ulvöspinel) are narrow (5-20 μm) curvilinear zones of glass associated with secondary kirschteinite, clinopyroxene and olivine (which show similar curvilinear morphology and truncate kirschsteinite lamellae). Glass compositions plot close to a mixing line between anorthite and ulvöspinel. Replicate oxygen isotopic analyses of acid-washed minerals by laser fluorination gave δ18O = 3.881, 3.845, δ17O = 1.967, 1.927, Δ17O = -0.0745, -0.0956 per mil (for TFL slope = 0.526). Comparison With NWA 2999: We previously showed [1] that angrite Northwest Africa 2999 is a metamorphically annealed breccia with distinctive symplectites and coronas representing forward and reverse versions of the same solid state reaction. We suggested that these disequilibrium textures required burial

  1. Transamazonic foundation from Borborema Province

    International Nuclear Information System (INIS)

    Geochronological data obtained in plutonic rocks of the Sao Vicente/Caico Groups present U/Pb values around 2.15 Ga. These rocks may have involved from an initial mantle or lower crust melting and fractionation process by 2.62-2.65 Ga., that is evidenced from Sm/Nd model ages. Relation betwen TTG-sequence and tectonic setting of the area and other localities in NE-Brazil suggest that the Transamazonic orogeny was the main crust-forming episode of the Borborema Province. (author)

  2. Contributions to the knowledge of Atlantic Canadian Histeridae (Coleoptera

    Directory of Open Access Journals (Sweden)

    Christopher Majka

    2008-09-01

    Full Text Available New records of Histeridae from Atlantic Canada are reported. Three species are newly recorded from Prince Edward Island and two from New Brunswick, one of which, the introduced Palearctic Atholus bimaculatus (Linnaeus, is newly recorded from Atlantic Canada as a whole. These new records increase the known histerid fauna of the region to 37 species, 30 native and 7 introduced ones. The regional zoogeography of the Histeridae is examined focusing on differences between the faunal composition of the various provinces and the possible reasons responsible for these. The island faunas of Cape Breton, Prince Edward Island, and Newfoundland are examined. All have reduced faunas in comparison with the mainland perhaps as a result of island-associated diminutions, an area effect, a paucity of collecting, or a combination of these factors. Those of Cape Breton and Prince Edward Island are proportionately similar to those of other families of Coleoptera, whereas that of Newfoundland (only 10% of the mainland fauna is significantly less, a circumstance which deserves further investigation. Seven species of introduced histerids have been recorded in the region. The average dates of first detection of these species are much later than the earliest records of these species in North America and comparatively later than is the case with other suites of introduced species in the Staphylinidae and Carabidae, perhaps as a result of the sparse attention the Histeridae have historically received by coleopterists in the region. Most of the introduced histerids are known to be synanthropic and may have been introduced to the region association with the importation of livestock and materials related to animal husbandry. The Histeridae of the region largely fall into one of several trophic guilds: coastal species and those associated with beach-drift material; species associated with bird nests; species associated with mammal nests; myrmecophilus species; saproxylic

  3. Biodiversity and ecological composition of macrobenthos on cold-water coral mounds and adjacent off-mound habitat in the bathyal Porcupine Seabight, NE Atlantic

    OpenAIRE

    Henry, L.A. (Lea Anne); Roberts, M. J.

    2007-01-01

    The cold-water scleractinian corals Lophelia pertusa and Madrepora oculata form mound structures on the continental shelf and slope in the NE Atlantic. This study is the first to compare the taxonomic biodiversity and ecological composition of the macrobenthos between on- and off-mound habitats. Seven box cores from the summits of three mounds and four cores from an adjacent off-mound area in the Belgica, Mound Province in the Porcupine Seabight yielded 349 species, including 10 undescribed s...

  4. Microbial assemblages on a cold-water coral mound at the SE Rockall Bank (NE Atlantic): interactions with hydrography and topography

    OpenAIRE

    J. D. L. van Bleijswijk; Whalen, C.; Duineveld, G.C.A.; Lavaleye, M.S.S.; Witte, H.J.; Mienis, F.

    2015-01-01

    This study characterizes the microbial community composition over Haas Mound, one of the most prominent cold-water coral mounds of the Logachev Mound province (Rockall Bank, NE Atlantic). We outline patterns of distribution vertically – from the seafloor to the water column – and laterally – across the mound – and couple these to mound topography and hydrography. Samples of water, sediment and Lophelia pertusa were collected in 2012 and 2013 from locations that were chose...

  5. Endeavor research into evolving paradigms around ophiolites: the case of the oceanic igneous complexes of Costa Rica

    International Nuclear Information System (INIS)

    Studies on the radiolarite igneous (ophiolitic) complexes were done for more than one century in Costa Rica that range from Jurassic to Eocene. These studies can be grouped in four stages of knowledge: 1) from 1904 to 1957 were recognized the cherts, and the mafic and ultramafic igneous complexes, the first regional maps were done, and the first time were recognized ellipsoidal basalts, now widely known as pillow lavas. 2) From 1958 to 1978 the complexes were seen under the concept of the association of ophiolites (serpentine, gabbro, diabase, basalts, and related rocks) and interpreted the radiolarites as deep-sea sediments. The stage is characterized by the seminal work of Gabriel Dengo and by the first geochemical analyses in the framework of the plate tectonics. 3) A huge amount of geochemical data, paleontological and K/Ar ages were published from 1979 to 1994 and it was the stage of more controversial papers, their interpretation varied for the same locality (i.e. (Nicoya Peninsula) from relative simple stratigraphic model to a very complex nappe slices, and from a simple tectonic evolution (in situ and formed by a mid oceanic ridge volcanism) to a multistage evolution (terrains, and mid oceanic ridge, aseismic ridge, intraplate and island arc volcanism). The situation was similar in the other Costa Rican oceanic complexes. 4) The outlook for 1995 to the present it has been clarified and mutual agreement between the different groups. The stage is characterized by joint collaboration, the use of modern laboratory techniques as Sr, Nd, and Pb isotopes, major, trace and complete rare earth elements. 40Ar/39Ar dating, and volcanological criteria, together with detailed field mapping. The main new result of these studies was that the radiolarites (164-84 Ma) in the Nicoya Peninsula were significatively older than the basic igneous rocks (140-84 Ma), indicating a complex magmatic event intruding and erupting into the thick sedimentary sequence. For other areas

  6. Large silica-rich igneous-textured inclusions in the Buzzard Coulee chondrite: Condensates, differentiates, or impact melts?

    Science.gov (United States)

    Ruzicka, Alex; Hutson, Melinda; Floss, Christine; Hildebrand, Alan

    2012-11-01

    We studied three large (2-4 mm diameter) igneous-textured inclusions in the Buzzard Coulee (H4) chondrite using microanalytical techniques (OLM, SEM, EMPA, SIMS) to better elucidate the origins of igneous inclusions in ordinary chondrites. The inclusions are clasts that come in two varieties (1) white inclusions Bz-1 and Bz-2 represent a nearly holocrystalline assemblage of low-Ca and high-Ca pyroxene (63-66 area%) and cristobalite (33-36%) and (2) tan inclusion Bz-3 is glass-rich (approximately 60%) with low-Ca and high-Ca pyroxene phenocrysts. The bulk compositions of the inclusions determined by modal reconstruction are all SiO2-rich (approximately 67 wt% for Bz-1 and Bz-2, approximately 62% for Bz-3), but Bz-3 is enriched in incompatible elements (e.g., REE approximately 4-5 × CI abundances), whereas Bz-2 and Bz-1 are depleted in those elements that are most incompatible in pyroxene (e.g., La-Ho approximately 0.15-0.4 × CI abundances). These bulk compositions do not resemble what one would expect for partial or complete shock melting of a chondritic precursor, and show no evidence for overall volatility control. We infer that the inclusions originated through igneous differentiation and FeO reduction, with Bz-3 forming as an "andesitic" partial melt (approximately 30-40% partial melting of an H chondrite precursor), and Bz-1 and Bz-2 forming as pyroxene-cristobalite cumulates from an Si-rich melt. We suggest that both types of melts experienced a period of transit through a cold, low-pressure space environment in which cooling, FeO reduction, and interaction with a vapor occurred. Melts may have been lofted into space by excavation or splashing during collisions, or by pyroclastic volcanism. Our results indicate intriguing similarities between the inclusions in Buzzard Coulee and the silicates in some iron (IIE-type) and stony iron (IVA-type) meteorites, suggesting a genetic relationship.

  7. Influence of the Iceland mantle plume on North Atlantic continental margins

    Science.gov (United States)

    White, R. S.; Isimm Team

    2003-04-01

    Early Tertiary breakup of the North Atlantic was accompanied by widespread magmatism. The histories of the Iceland mantle plume, of rifting and of magmatism are intimately related. The magmatism provides a challenge both to imaging structure, and to modelling the subsidence and development of the continental margins. We report new work which integrates state-of-the-art seismic imaging and new acquisition on the Atlantic volcanic margins with new techniques for modelling their evolution. We discuss the distribution of igneous rocks along the North Atlantic margins and discuss the temporal and spatial variations in the Iceland mantle plume in the early Tertiary, which have largely controlled this pattern of magmatism. Igneous rocks are added to the crust on rifted margins as extrusive lavas, as sills intruded into the sub-surface and as lower crustal intrusions or underplate. Each provide different, but tractable problems to seismic imaging. We show that many of these difficulties can be surmounted by using very long offsets (long streamers or two-ship methods) with a broad-band, low-frequency source, and by using fixed ocean bottom receivers. We report results from surveys on the North Atlantic continental margins using these methods. Imaging results are shown from the recent FLARE project and from the iSIMM project, which recorded new seismic data recorded in summer 2002. The iSIMM project acquired two seismic surveys, using 85 4-component ocean bottom seismometers with long streamers for wide-angle data, and vertical arrays for far-field source signature recording. One survey crosses the Faroes Shelf and adjacent continental margin, and a second the Hatton-Rockall Basin, Hatton Bank and adjacent oceanic crust. The Faroes wide-angle profiles were overshot by WesternGeco's Topaz using three single-sensor, Q-Marine streamers, 12km plus two 4km. We designed deep-towed, broad-band low-frequency sources tuned to enhance the bubble pulses, with peak frequencies at 8

  8. Revisiting the magnetostratigraphy of the Central Atlantic Magmatic Province (CAMP) in Morocco

    Czech Academy of Sciences Publication Activity Database

    Font, E.; Youbi, N.; Fernandes, S.; El Hachimi, H.; Kratinová, Zuzana; Hamim, Y.

    2011-01-01

    Roč. 309, č. 3-4 (2011), s. 302-317. ISSN 0012-821X Institutional research plan: CEZ:AV0Z30120515 Keywords : CAMP * Morocco * remagnetization * magnetostratigraphy * Triassic-Jurassic boundary Subject RIV: DB - Geology ; Mineralogy Impact factor: 4.180, year: 2011

  9. Three Stages of Mesozoic Bimodal Igneous Rocks and Their Tectonic Implications on the Continental Margin of Southeastern China

    Institute of Scientific and Technical Information of China (English)

    XING Guangfu; YANG Zhuliang; CHEN Rong; SHEN Jialin; WEI Naiyi; ZHOU Yuzhang

    2004-01-01

    There are large-scale Mesozoic bimodal igneous rock associations on the continental margin of southeastern China. They aroused extensive attention in the 1980s because of their specific tectonic implications, and have been found frequently during recent geological surveys. This paper reviews the studies of regional Mesozoic bimodal rocks, and concludes that they can be subdivided into three stages, i.e., the Early Jurassic (209-170 Ma, the first (Ⅰ) stage), the Late Jurassic-early Early Cretaceous (154-121 Ma, the second (Ⅱ) stage), and the late Early Cretaceous-Late Cretaceous (115-85 Ma, the third (Ⅲ) stage). These three stages of bimodal rocks were formed in different tectonic settings, and are important indicators for regional Mesozoic tectonic evolution.

  10. An Atlantic influence on Amazon rainfall

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jin-Ho [University of Maryland, Department of Atmospheric and Oceanic Science, College Park, MD (United States); Zeng, Ning [University of Maryland, Earth System Science Interdisciplinary Center, College Park, MD (United States); University of Maryland, Department of Atmospheric and Oceanic Science, College Park, MD (United States)

    2010-02-15

    Rainfall variability over the Amazon basin has often been linked to variations in Pacific sea surface temperature (SST), and in particular, to the El Nino/Southern Oscillation (ENSO). However, only a fraction of Amazon rainfall variability can be explained by ENSO. Building upon the recent work of Zeng (Environ Res Lett 3:014002, 2008), here we provide further evidence for an influence on Amazon rainfall from the tropical Atlantic Ocean. The strength of the North Atlantic influence is found to be comparable to the better-known Pacific ENSO connection. The tropical South Atlantic Ocean also shows some influence during the wet-to-dry season transition period. The Atlantic influence is through changes in the north-south divergent circulation and the movement of the ITCZ following warm SST. Therefore, it is strongest in the southern part of the Amazon basin during the Amazon's dry season (July-October). In contrast, the ENSO related teleconnection is through anomalous east-west Walker circulation with largely concentrated in the eastern (lower) Amazon. This ENSO connection is seasonally locked to boreal winter. A complication due to the influence of ENSO on Atlantic SST causes an apparent North Atlantic SST lag of Amazon rainfall. Removing ENSO from North Atlantic SST via linear regression resolves this causality problem in that the residual Atlantic variability correlates well and is in phase with the Amazon rainfall. A strong Atlantic influence during boreal summer and autumn is particularly significant in terms of the impact on the hydro-ecosystem which is most vulnerable during the dry season, as highlighted by the severe 2005 Amazon drought. Such findings have implications for both seasonal-interannual climate prediction and understanding the longer-term changes of the Amazon rainforest. (orig.)

  11. Geochronology of igneous rocks and formation of the Late Paleozoic south Mongolian active margin of the Siberian continent

    Science.gov (United States)

    Yarmolyuk, V. V.; Kovalenko, V. I.; Sal'Nikova, E. B.; Kovach, V. P.; Kozlovsky, A. M.; Kotov, A. B.; Lebedev, V. I.

    2008-04-01

    The succession of magmatic events associated with development of the Early Carboniferous-Early Permian marginal continental magmatic belt of southern Mongolia is studied. In the belt structure there are defined the successive rock complexes: the older one represented by differentiated basalt-andesite-rhyodacite series and younger bimodal complex of basalt-comendite-trachyrhyolite composition. The granodiorite-plagiogranite and banatite (diorite-monzonite-granodiorite) plutonic massifs are associated with the former, while peralkaline granite massifs are characteristic of the latter. First systematic geochronological study of igneous rock associations is performed to establish time succession and structural position of both complexes. Geochronological results and geological relations between rocks of the bimodal and differentiated complexes showed first that rocks of the differentiated complex originated 350 to 330 Ma ago at the initial stage of development of the marginal continental belt. This is evident from geochronological dates obtained for the Adzh-Bogd and Edrengiyn-Nuruu massifs and for volcanic associations of the complex. The dates are consistent with paleontological data. The bimodal association was formed later, 320 to 290 Ma ago. The time span separating formation of two igneous complexes ranges from several to 20 30 m.y. in different areas of the marginal belt. The bimodal magmatism was interrelated with rifting responsible for development of the Gobi-Tien Shan rift zone in the belt axial part and the Main Mongolian lineament along the belt northern boundary. Loci of bimodal rift magmatism likely migrated with time: the respective magmatic activity first initiated on the west of the rift system and then advanced gradually eastward with development of rift structures. Normal granitoids untypical but occurring nevertheless among the products of rift magmatism in addition to peralkaline massifs are assumed to have been formed, when the basic magmatism

  12. Onboard calibration igneous targets for the Mars Science Laboratory Curiosity rover and the Chemistry Camera laser induced breakdown spectroscopy instrument

    International Nuclear Information System (INIS)

    Accurate characterization of the Chemistry Camera (ChemCam) laser-induced breakdown spectroscopy (LIBS) on-board composition targets is of prime importance for the ChemCam instrument. The Mars Science Laboratory (MSL) science and operations teams expect ChemCam to provide the first compositional results at remote distances (1.5-7 m) during the in situ analyses of the Martian surface starting in 2012. Thus, establishing LIBS reference spectra from appropriate calibration standards must be undertaken diligently. Considering the global mineralogy of the Martian surface, and the possible landing sites, three specific compositions of igneous targets have been determined. Picritic, noritic, and shergottic glasses have been produced, along with a Macusanite natural glass. A sample of each target will fly on the MSL Curiosity rover deck, 1.56 m from the ChemCam instrument, and duplicates are available on the ground. Duplicates are considered to be identical, as the relative standard deviation (RSD) of the composition dispersion is around 8%. Electronic microprobe and laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) analyses give evidence that the chemical composition of the four silicate targets is very homogeneous at microscopic scales larger than the instrument spot size, with RSD 0.1 wt.% using electronic microprobe, and 0.01 wt.% using LA ICP-MS. The LIBS campaign on the igneous targets performed under flight-like Mars conditions establishes reference spectra for the entire mission. The LIBS spectra between 240 and 900 nm are extremely rich, hundreds of lines with high signal-to-noise, and a dynamical range sufficient to identify unambiguously major, minor and trace elements. For instance, a first LIBS calibration curve has been established for strontium from [Sr] = 284 ppm to [Sr] = 1480 ppm, showing the potential for the future calibrations for other major or minor elements.

  13. Onboard calibration igneous targets for the Mars Science Laboratory Curiosity rover and the Chemistry Camera laser induced breakdown spectroscopy instrument

    Energy Technology Data Exchange (ETDEWEB)

    Fabre, C., E-mail: cecile.fabre@g2r.uhp-nancy.fr [G2R, Nancy Universite (France); Maurice, S.; Cousin, A. [IRAP, Toulouse (France); Wiens, R.C. [LANL, Los Alamos, NM (United States); Forni, O. [IRAP, Toulouse (France); Sautter, V. [MNHN, Paris (France); Guillaume, D. [GET, Toulouse (France)

    2011-03-15

    Accurate characterization of the Chemistry Camera (ChemCam) laser-induced breakdown spectroscopy (LIBS) on-board composition targets is of prime importance for the ChemCam instrument. The Mars Science Laboratory (MSL) science and operations teams expect ChemCam to provide the first compositional results at remote distances (1.5-7 m) during the in situ analyses of the Martian surface starting in 2012. Thus, establishing LIBS reference spectra from appropriate calibration standards must be undertaken diligently. Considering the global mineralogy of the Martian surface, and the possible landing sites, three specific compositions of igneous targets have been determined. Picritic, noritic, and shergottic glasses have been produced, along with a Macusanite natural glass. A sample of each target will fly on the MSL Curiosity rover deck, 1.56 m from the ChemCam instrument, and duplicates are available on the ground. Duplicates are considered to be identical, as the relative standard deviation (RSD) of the composition dispersion is around 8%. Electronic microprobe and laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) analyses give evidence that the chemical composition of the four silicate targets is very homogeneous at microscopic scales larger than the instrument spot size, with RSD < 5% for concentration variations > 0.1 wt.% using electronic microprobe, and < 10% for concentration variations > 0.01 wt.% using LA ICP-MS. The LIBS campaign on the igneous targets performed under flight-like Mars conditions establishes reference spectra for the entire mission. The LIBS spectra between 240 and 900 nm are extremely rich, hundreds of lines with high signal-to-noise, and a dynamical range sufficient to identify unambiguously major, minor and trace elements. For instance, a first LIBS calibration curve has been established for strontium from [Sr] = 284 ppm to [Sr] = 1480 ppm, showing the potential for the future calibrations for other major or minor

  14. The offshore basement of Perú: Evidence for different igneous and metamorphic domains in the forearc

    Science.gov (United States)

    Romero, Darwin; Valencia, Kiko; Alarcón, Pedro; Peña, Daniel; Ramos, Victor A.

    2013-03-01

    As a result of new studies carried out in the offshore of Perú during the exploration and hydrocarbon evaluation of the forearc basins, new U-Pb SHRIMP and TIMS in zircons and some Ar-Ar data were obtained in the metamorphic and igneous basement. The understanding of this basement was critical to evaluate different hypotheses that have been proposed for the tectonic evolution of pre-Andean crust of Perú. Recent research performed in the basement rocks of the Marañón Massif in northern Perú, claimed that west of this area was a basement-free region in the Paleozoic, where the arc and forearc were developed in a mafic quasi-oceanic crust. However, petrographic studies and new preliminary ages indicate, for the first time, the nature and age of this sialic basement. Reconnaissance studies were performed in several offshore islands, as the Las Hormigas de Afuera Island west of Lima, and Macabí and Lobera islands along the edge of the continental platform. These data were complemented with the studies of some cutting samples obtained in recent exploration wells in northern Perú. The results of the present work show two large crustal domains in the Peruvian offshore forearc. A northern domain contains late Paleozoic igneous rocks that appear to be the southern offshore continuation of the Amotape-Tahuin block, which is interpreted as the southernmost remnant of the Laurentia Alleghenian orogen. The central offshore domain, known as the Paracas High, corresponds to the outer shelf high of previous studies. It contains orthogneisses of Grenville-age, probably recrystallized during an Ordovician magmatic episode. The new results show that the central offshore of Perú is an extension of the Grenville-age basement affected by Famatinian, early Paleozoic magmatism, well exposed in the southern domain in the Arequipa Massif along the coast of southern Perú.

  15. The LA-ICP-MS zircons U-Pb ages and geochemistry of the Baihua basic igneous complexes in Tianshui area of West Qinling

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Baihua meta-igneous complex consists mainly of pyroxenite-gabbro(diorite)-diorite-quartz diorite. They form a complete comagmatic evolutionary series. The geochemical characteristics of basic-interme- diate basic igneous rocks indicate that they belong to a tholeiite suite. The REE distribution pattern is nearly flat type and LREE is slightly enriched type, and their primitive mantle-normalized and MORB-normalized trace element spider diagrams are generally similar; the LIL elements (LILE) Cs, Ba, Sr, Th and U are enriched, but Rb, K and the HFSEs Nb, P, Zr, Sm, Ti and Y are relatively depleted. All these show comagmatic evolution and origin characteristics. The tectonics environment discrimination of trace element reveals that these igneous complexes formed in an island-arc setting. The LA-ICP-MS single-zircons U-Pb age of Baihua basic igneous complex is 434.6±1.5 Ma (MSWD = 1.3), which proves that the formation time of the island-arc type magmatite in the northern zone of West Qinling is Late Ordovician or Early Silurian, also reveals that the timing of subduction of paleo-ocean basin represented by the Guanzizhen ophiolite and resulting island-arc-type magmatic activities is probably Middle-Late Ordovician to Early Silurian.

  16. K-Ar ages of hornblende from the granodiorite in the Kuraoka igneous rocks around Mt. Gion-yama in the Kurosegawa structural belt, central Kyushu

    International Nuclear Information System (INIS)

    Palaeozoic Gion-yama facies of Kurosegawa structural belt which distribute in central region of Gokase town near the northern border of Miyazaki prefecture, is known to belong to Silur-Devonian series by coral fossils in limestone. Igneous rocks and metamorphic rocks of Kuraoka-yama which located in its neghborhood, were undergone petrological studies and structural studies previously, but their ages were not determined yet. K-Ar age determination of hornblende in granodiorite of Kuraoka-yama igneous rock series was attempted. This granodiorite is classified into two facies, namely granodiorite, the constituent minerals of which are identfied macroscopically, and leucocratic mylonitized granite, but without remarkable substantial difference between them. Hornblende for age determination was collected from former. K-Ar age was determined by repeated measurements and obtained mean age was 450 Ma. As correlated with isotope ages of Mitaki igneous rocks of Kurosegawa structural belt which were studied previously, the obtained value was the oldest and correlated to Ordovician period. This result means that calc-alkaline igneous activity took place in older age than Gion-yama facies. The obtained result is expected to provide data for explaining the relations between granodiorite and conodont bearing Ordovician facies of Kurosegawa structural belt of Shikoku, petrological correlation of acidic rocks, and for discussing geology of older age. (Ishimitsu, A.)

  17. Neoproterozoic igneous complex emplaced along major tectonic boundary in the Kaoko Belt (NW Namibia): ion probe and LA-ICP-MS dating of magmatic and metamorphic zircons

    Czech Academy of Sciences Publication Activity Database

    Konopásek, J.; Košler, J.; Tajčmanová, L.; Ulrich, Stanislav; Kitt, S. L.

    2008-01-01

    Roč. 165, č. 1 (2008), s. 153-166. ISSN 0016-7649 Institutional research plan: CEZ:AV0Z30120515 Keywords : boundary igneous complex * Kaoko Belt * zircon Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.797, year: 2008

  18. Bacterioplankton Biogeography of the Atlantic Ocean: A Case Study of the Distance-Decay Relationship

    Science.gov (United States)

    Milici, Mathias; Tomasch, Jürgen; Wos-Oxley, Melissa L.; Decelle, Johan; Jáuregui, Ruy; Wang, Hui; Deng, Zhi-Luo; Plumeier, Iris; Giebel, Helge-Ansgar; Badewien, Thomas H.; Wurst, Mascha; Pieper, Dietmar H.; Simon, Meinhard; Wagner-Döbler, Irene

    2016-01-01

    In order to determine the influence of geographical distance, depth, and Longhurstian province on bacterial community composition and compare it with the composition of photosynthetic micro-eukaryote communities, 382 samples from a depth-resolved latitudinal transect (51°S–47°N) from the epipelagic zone of the Atlantic ocean were analyzed by Illumina amplicon sequencing. In the upper 100 m of the ocean, community similarity decreased toward the equator for 6000 km, but subsequently increased again, reaching similarity values of 40–60% for samples that were separated by ~12,000 km, resulting in a U-shaped distance-decay curve. We conclude that adaptation to local conditions can override the linear distance-decay relationship in the upper epipelagial of the Atlantic Ocean which is apparently not restrained by barriers to dispersal, since the same taxa were shared between the most distant communities. The six Longhurstian provinces covered by the transect were comprised of distinct microbial communities; ~30% of variation in community composition could be explained by province. Bacterial communities belonging to the deeper layer of the epipelagic zone (140–200 m) lacked a distance-decay relationship altogether and showed little provincialism. Interestingly, those biogeographical patterns were consistently found for bacteria from three different size fractions of the plankton with different taxonomic composition, indicating conserved underlying mechanisms. Analysis of the chloroplast 16S rRNA gene sequences revealed that phytoplankton composition was strongly correlated with both free-living and particle associated bacterial community composition (R between 0.51 and 0.62, p < 0.002). The data show that biogeographical patterns commonly found in macroecology do not hold for marine bacterioplankton, most likely because dispersal and evolution occur at drastically different rates in bacteria. PMID:27199923

  19. Triassic post collision igneous activity and granulite facies metamorphic event in the Yangpyeong area, South Korea and its meaning to the tectonics of Northeast Asia

    Science.gov (United States)

    Lee, S.; Oh, C.

    2009-12-01

    The Korean peninsula is tectonically positioned in the eastern margin of the Asia continent and the Gyeonggi massif is situated in the center part of Korean peninsula. Triassic (231 Ma) eclogite was first found in the Hongseong area, the southwestern part of the Gyeonggi Massif, which suggested that the Hongseong area is the extension of Triassic collision belt between the North and South China blocks, in China. The 257-226 post-collisional mangerite was also found in the Odesan area, the eastern part of Gyeonggi massif. Based on these new findings, it was proposed that the line connecting Hongseong and Odesan areas is the collision belt between the North and South China blocks. It was also reported that 247 Ma ultrahigh temperature metamorphism occurred together with the intrusion of mangerite in the Odesan area indicating that regional metamorphism occurred together with the post-collision igneous activity. The Yangpyeong area locates in the middle part of the Hongseong-Odesan collision belt. The area mainly consists of Precambrian migmatitic gneiss which was intruded by Triassic igneous complex. The igneous complex mainly consists of gabbro and porpyritic syeno-diorite and SHRIMP age dating indicates that they intruded at 227 ± 4 Ma. They are shoshonitic and high-K series and have high Ba, Sr contents. They show LREE enriched pattern and Nb, Ta, P, Ti depletion in the chondrite- and primitive-mantle-normalized trace element patterns, respectively. In the tectonic discrimination diagrams, gabbros are plotted in the within plate tectonic field and porpyritic syeno-diorites are plotted in the Post-collision field. These geochemical characters indicate that they formed in the within plate after continental collision. Two metamorphic ages (1861 ± 6 Ma, and 235 ± 6 Ma) are obtained from the migmatitic gneiss. The peak metamorphic conditions of the first Precambrian metamorphism are 750-780°C and 8-10 kbar indicating intermediate-P/T metamorphism. On the other hand

  20. 78 FR 3401 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Science.gov (United States)

    2013-01-16

    ...; Atlantic Mackerel, Squid, and Butterfish Fisheries; Scoping Process; Mid-Atlantic Fishery Management... support for an amendment (Amendment 16) to the Fishery Management Plan (FMP) for Atlantic Mackerel,...

  1. Petrology and mineralogy of the La Peña igneous complex, Mendoza, Argentina: An alkaline occurrence in the Miocene magmatism of the Southern Central Andes

    Science.gov (United States)

    Pagano, Diego Sebastián; Galliski, Miguel Ángel; Márquez-Zavalía, María Florencia; Colombo, Fernando

    2016-04-01

    The La Peña alkaline igneous complex (LPC) is located in the Precordillera (32°41‧34″ S - 68°59‧48″ W) of Mendoza province, Argentina, above the southern boundary of the present-day flat-slab segment. It is a 19 km2 and 5 km diameter subcircular massif emplaced during the Miocene (19 Ma) in the Silurian-Devonian Villavicencio Fm. The LPC is composed of several plutonic and subvolcanic intrusions represented by: a cumulate of clinopyroxenite intruded by mafic dikes and pegmatitic gabbroic dikes, isolated bodies of malignite, a central intrusive syenite that develops a wide magmatic breccia in the contact with clinopyroxenite, syenitic and trachytic porphyries, a system of radial and ring dikes of different compositions (trachyte, syenite, phonolite, alkaline lamprophyre, tephrite), and late mafic breccias. The main minerals that form the LPC, ordered according to their abundance, are: pyroxene (diopside, hedenbergite), calcium amphibole (pargasite, ferro-pargasite, potassic-ferro-pargasite, potassic-hastingsite, magnesio-hastingsite, hastingsite, potassic-ferro-ferri-sadanagaite), trioctahedral micas (annite-phlogopite series), plagioclase (bytownite to oligoclase), K-feldspar (sanidine and orthoclase), nepheline, sodalite, apatite group minerals (fluorapatite, hydroxylapatite), andradite, titanite, magnetite, spinel, ilmenite, and several Cu-Fe sulfides. Late hydrothermal minerals are represented by zeolites (scolecite, thomsonite-Ca), epidote, calcite and chlorite. The trace element patterns, coupled with published data on Sr-Nd-Pb isotopes, suggest that the primary magma of the LPC was generated in an initially depleted but later enriched lithospheric mantle formed mainly by a metasomatized spinel lherzolite, and that this magmatism has a subduction-related signature. The trace elements pattern of these alkaline rocks is similar to other Miocene calc-alkaline occurrences from the magmatic arc of the Southern Central Andes. Mineral and whole

  2. Growth of Transgressive Sills in Mechanically Layered Media: Faroe Islands, NE Atlantic Margin

    Science.gov (United States)

    Walker, R. J.

    2014-12-01

    Igneous sills represent an important contribution to upper crustal magma transport, acting as magma conduits and stores (i.e. as sill networks, or as nascent magma chambers). Complex sill-network intrusion in basin settings can have significant impact on subsurface fluid flow (e.g., water aquifer and hydrocarbon systems), geothermal systems, the maturation of hydrocarbons, and methane release. Models for these effects are critically dependent on the models for sill emplacement. This study focuses on staircase-geometry sills in the Faroe Islands, on the European Atlantic Margin, which are hosted in mechanically layered lavas (1-20 m thick) and basaltic volcaniclastic units (1-30 m thick). The sills range from 20-50 m thick, with each covering ~17 km2, and transgressing a vertical range of ~480 m. Steps in the sills are elliptical in cross section, and discontinuous laterally, forming smooth transgressive ramps, hence are interpreted as representing initial stages of sill propagation as magma fingers, which inflate through time to create a through-going sheet. Although steps correspond to the position of some host rock layer interfaces and volcaniclastic horizons, most interfaces are bypassed. The overall geometry of the sills is consistent with ENE-WSW compression, and NNW-SSE extension, and stress anisotropy-induced transgression. Local morphology indicates that mechanical layering suppressed tensile stress ahead of the crack tip, leading to a switch in minimum and intermediate stress axes, facilitating lateral sill propagation as fingers, and resulting in a stepped transgressive geometry.

  3. Customary Homicides in Diyarbakir Province.

    Science.gov (United States)

    Yilmaz, Eyyup; Canturk, Nergis; Erkol, Zerrin; Kumral, Bahadir; Okumus, Ali M

    2015-09-01

    This study presents an analysis of the causes of so-called honor killings in the context of "customary homicide" and a discussion of preventive measures. Finalized case files of customary homicide between January 1, 2007 and December 31, 2012 were retrospectively examined in Diyarbakir Province, Turkey. Of a total of 28 case victims, 17 (60.7%) were females and 11 (39.3%) were males. All perpetrators were male. There was a significant difference between male and female victims in terms of economic independence (p=0.000). A direct blood relationship or relationship by marriage (such as brother-in-law) was found to have a significant association with the gender of the victim (pwomen by society, replacement of patriarchal models with more modern attitudes, and encouragement of individuality may represent effective strategies that may help reduce the number of customary homicide, which represents a multifaceted problem. PMID:25921219

  4. Paleoproterozoic Greenstone-Granite Belts in Northern Brazil and the Former Guyana Shield - West African Craton Province

    Directory of Open Access Journals (Sweden)

    Ian McReath

    2006-03-01

    Full Text Available The mainly meta-volcano-sedimentary Vila Nova Group and associated granites constitute separate belts, which formpart of a large paleoproterozoic (mainly rhyacian province in the Guyana Shield of which northern Brazil forms a part, andthe West African Craton. In Brazil the southwestern Serra do Ipitinga and Serra Tumucumaque-Serra do Navio belts have noobvious geometrical extensions in the Guyanas or Venezuela, and may represent deposits formed at penecontemporaneouspassive continental margins and ocean floor spreading centres. To the Northeast the Serra Lombarda-Tartarugalzinho andOiapoque belts are continuations of Guianese belts. In the former the igneous rocks have geochemical characteristics ofsuprasubduction environments. Belts in the Guyana Shield and West African Craton have many similar features. Themegaprovince evolved in a number of stages, which may have started at about 2.3 Ga, and continued with diminished activityafter 2.11 Ga. Both major juvenile additions and (possibly minor reworking of earlier crust contributed to the growth of theprovince. The major transcurrent deformation, responsible for the present structure of the belts, probably occurred duringthe later stages of evolution of the province, but metamorphism and deformation are registered even in the oldest rocks.

  5. Phytoplankton growth and microzooplankton grazing in the subtropical Northeast Atlantic.

    Directory of Open Access Journals (Sweden)

    Carlos Cáceres

    Full Text Available Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates during two Lagrangian surveys in inner and eastern locations of the Eastern North Atlantic Subtropical Gyre province (NAST-E. Our design included two phytoplankton size fractions (0.2-5 µm and >5 µm and five depths, allowing us to characterize differences in growth and grazing rates between size fractions and depths, as well as to estimate vertically integrated measurements. Phytoplankton growth rates were high (0.11-1.60 d(-1, especially in the case of the large fraction. Grazing rates were also high (0.15-1.29 d(-1, suggesting high turnover rates within the phytoplankton community. The integrated balances between phytoplankton growth and grazing losses were close to zero, although deviations were detected at several depths. Also, O2 supersaturation was observed up to 110 m depth during both Lagrangian surveys. These results add up to increased evidence indicating an autotrophic metabolic balance in oceanic subtropical gyres.

  6. Atlantic energy and the strategic outlook

    Directory of Open Access Journals (Sweden)

    Paul Isbell

    2013-09-01

    Full Text Available Sweeping changes are beginning to transform energy scenarios around the world. The gas revolution, a renaissance in petroleum technology and exploration, and a chaotic but powerful movement toward the goal of low-carbon economies are three of the principal energy trends currently interacting with structural changes in the geo-economics of the Atlantic world to present new perspectives and opportunitiesfor the diverse actors in the ‘Atlantic Basin’. This article explores how changes in the energy landscape are contributing to a reassessment of the strategic horizon. The potential impacts of the shale revolution, deep-offshore oil, biofuels and other modern renewable energies on the geopolitics of the Atlantic Basin will be assessed, and the hypothesis that an Atlantic Basin energy system is now taking shape will be evaluated, along with an analysis of anticipated impacts.

  7. North Atlantic Coastal Plain aquifer system

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the North Atlantic Coastal Plain aquifer system in North Carolina, Virginia, Maryland, Deleware, and New Jersey.

  8. Atlantic Sharpnose Shark Reproductive Biology Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Reproductive data from Atlantic sharpnose sharks were collected from specimens captured throughout the northern Gulf of Mexico on various research vessels. Data...

  9. Atlantic NAD 83 SLA Baseline Tangents

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains baseline tangent lines in ArcGIS shapefile format for the BOEM Atlantic Region. Baseline tangent lines are typically bay or river closing...

  10. Atlantic NAD 83 SLA Baseline Points

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains baseline points in ArcGIS shapefile format for the BOEM Atlantic Region. Baseline points are the discrete coordinate points along the...

  11. Atlantic NAD 83 Continental Shelf Boundary (CSB)

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains Continental Shelf Boundary (CSB) lines in ESRI shapefile format for the BOEM Atlantic Region. The CSB defines the seaward limit of federally...

  12. Atlantic Marine Mammal Assessment Vessel Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data sets are a compilation of large vessel surveys for marine mammal stock assessments in South Atlantic (Florida to Maryland) waters from 1994 to the...

  13. Atlantic Surfclam and Ocean Quahog Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Atlantic Surfclam and Ocean Quahog Survey has covered an area from Cape Hatteras to Georges Bank. The survey was conducted every two or three...

  14. Ocean science: Vagaries of Atlantic overturning

    Science.gov (United States)

    Haine, Thomas W. N.

    2016-07-01

    A weakening of the Atlantic meridional overturning circulation has emerged from noise after years of painstaking measurements. Three independent lines of evidence suggest that an anthropogenic influence on this overturning is not yet detectable.

  15. Temperature fluctuations in the Atlantic Ocean

    International Nuclear Information System (INIS)

    The article discusses the temperature fluctuations in connection with drought in Africa, the climate in North America, the European heat waves and the frequent tropical hurricanes in the Atlantic Ocean. Problems with climate modelling and some pollution aspects are mentioned

  16. Genetic connectivity between north and south Mid-Atlantic Ridge chemosynthetic bivalves and their symbionts.

    Directory of Open Access Journals (Sweden)

    Karina van der Heijden

    Full Text Available Transform faults are geological structures that interrupt the continuity of mid-ocean ridges and can act as dispersal barriers for hydrothermal vent organisms. In the equatorial Atlantic Ocean, it has been hypothesized that long transform faults impede gene flow between the northern and the southern Mid-Atlantic Ridge (MAR and disconnect a northern from a southern biogeographic province. To test if there is a barrier effect in the equatorial Atlantic, we examined phylogenetic relationships of chemosynthetic bivalves and their bacterial symbionts from the recently discovered southern MAR hydrothermal vents at 5°S and 9°S. We examined Bathymodiolus spp. mussels and Abyssogena southwardae clams using the mitochondrial cytochrome c oxidase subunit I (COI gene as a phylogenetic marker for the hosts and the bacterial 16S rRNA gene as a marker for the symbionts. Bathymodiolus spp. from the two southern sites were genetically divergent from the northern MAR species B. azoricus and B. puteoserpentis but all four host lineages form a monophyletic group indicating that they radiated after divergence from their northern Atlantic sister group, the B. boomerang species complex. This suggests dispersal of Bathymodiolus species from north to south across the equatorial belt. 16S rRNA genealogies of chemoautotrophic and methanotrophic symbionts of Bathymodiolus spp. were inconsistent and did not match the host COI genealogy indicating disconnected biogeography patterns. The vesicomyid clam Abyssogena southwardae from 5°S shared an identical COI haplotype with A. southwardae from the Logatchev vent field on the northern MAR and their symbionts shared identical 16S phylotypes, suggesting gene flow across the Equator. Our results indicate genetic connectivity between the northern and southern MAR and suggest that a strict dispersal barrier does not exist.

  17. Potential uranium provinces in some arabian countries

    International Nuclear Information System (INIS)

    This work represents an attempt to delineate potential uranium provinces in some Arabian countries using various related recognition criteria. Definition of these provinces is based on the available geologic and tectonic setting beside geochronological sequence and some geochemical characteristics. This trial would be of a great help for interchanging the ideas and necessary data for the development in the fields of uranium exploration and production. As a result of this study, a number of promising potential uranium provinces are recommended in some arabian countries. 5 figs

  18. 40Ar/ 39Ar dating of the Jurassic volcanic province of Patagonia: migrating magmatism related to Gondwana break-up and subduction

    Science.gov (United States)

    Féraud, G.; Alric, V.; Fornari, M.; Bertrand, H.; Haller, M.

    1999-10-01

    The Mesozoic large igneous province (LIP) of Patagonia (southern South America), which is one of the largest silicic provinces on Earth has been investigated by the 40Ar/ 39Ar method. Twenty-seven ages considered as valid, including twenty plateau ages, show that the volcanic activity, ranging from 187 to 144 Ma, occurred between and contemporaneously with the initial break-up of Gondwana (starting with the Karoo-Antarctic-Tasmanian (KAT) flood basalt province) in the east, and a subduction in the west. The data display a regular decreasing of ages from the ENE (187 Ma) to the WSW (144 Ma) along about 650 km, apparently related to the tectonic structure in half-grabens oriented NNW-SSE. The good fitting of this trend with the opening of the Rocas Verdes-Sarmiento marginal basin favors a space time evolution of this continental volcanism culminating towards the SSW in a continental disruption behind the magmatic arc. The observed age progression of volcanism may be the result of the variations of the physical characteristics of the subduction. The spreading and thermal effect of the KAT plume may have an additional effect and also could account for the unusually large volume of magma.

  19. Extended history of a 3.5 Ga trondhjemitic gneiss, Wyoming Province, USA: Evidence from U-Pb systematics in zircon

    Science.gov (United States)

    Mueller, P.A.; Wooden, J.L.; Mogk, D.W.; Nutman, A.P.; Williams, I.S.

    1996-01-01

    The Beartooth-Bighorn magmatic zone (BBMZ) and the Montana metasedimentary province (MMP) are two major subprovinces of the Archean Wyoming province. In the northwestern Beartooth Mountains, these subprovinces are separated by a structurally, lithologically and metamorphically complex assemblage of lithotectonic units that include: (1) a strongly deformed complex of trondhjemitic gneiss and interlayered amphibolites; and (2) an amphibolite facies mafic unit that occurs in a nappe that structurally overlies the gneiss complex. Zircons from a trondhjemitic blastomylonite in the gneiss complex yield concordant U-Pb ages of 3.5 Ga, establishing it as the oldest rock yet documented in the Wyoming province. Two younger events are also recorded by zircons in this rock: (1) an apparently protracted period of high-grade metamorphism and/or intrusion of additional magmas at ??? 3.25 Ga; and (2) growth of hydrothermal zircon at ??? 2.55 Ga, apparently associated with ductile deformation that immediately preceded structural emplacement of the gneiss. Although this latter event appears confined to areas along the BBMZ-MMP boundary, evidence of ??? 3.25 Ga igneous activity is found in the overlying amphibolite (3.24 Ga) and throughout the MMP. These data suggest that this boundary first developed as a major intracratonic zone of displacement at or before 3.25 Ga. The limited occurrences of 2.8 Ga magmatic activity in the MMP suggest that it had a controlling influence on late Archean magmatism as well.

  20. Research on Fluid Inclusions of the Yinshan Polymetallic Deposit,Jiangxi Province,China

    Institute of Scientific and Technical Information of China (English)

    张德会; 刘伟

    1999-01-01

    In this paper some new advances in the study of fluid inclusions of the Yinshan deposit in Jiangxi Province,China,are presented.The fluid inclusions of the deposit can be divided into four types:1) gas-rich inclusions;2)liquid-rich inclusions;3)salt-saturated H2O inclusions;and 4)single-phase or multiphase CO2-rich inclusions.Homogenization temperatures of the fluid inclusions range from 100 to 520℃,aminly in the range 120-400℃.The daughter crystal-bearing multiphase inclusions present in quartz porphyries(including Nos.13 and 4 dikes)have been observed.In ore veins,some daughter crystal-bearing multiphase inclusions have been observed.too.On the basis of the results of fluid inclusion research,the authors suggest that the ore-forming fluid must have a close genetic relation to magmatic hydrothermal solution.The ore-forming fluid was dominantly originated from the depth and the mixing of magmatic solution with meteoric water was enhanced during ascending of the fluid,accompanying immiscibility and boiling of fluid.Teher may be a conceales igneous body at the depth of the Yinshan deposity,which furnishes the scientific basis for metallogenic prognosis at th depth of the Yinshan deposit.

  1. 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.

  2. 77 FR 61562 - Atlantic Highly Migratory Species; 2013 Atlantic Shark Commercial Fishing Season

    Science.gov (United States)

    2012-10-10

    ... accompanied the 2011 shark quota specifications rule (75 FR 76302; December 8, 2010). Thus, NMFS proposes to... Species; 2013 Atlantic Shark Commercial Fishing Season AGENCY: National Marine Fisheries Service (NMFS... season for the Atlantic commercial shark fisheries. Quotas would be adjusted as allowable based on...

  3. 75 FR 44938 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; Atlantic Coastal Shark Fishery

    Science.gov (United States)

    2010-07-30

    ... on April 27, 2010 (75 FR 22103), and are not repeated here. Activities Pursuant to the Atlantic... Management Act Provisions; Atlantic Coastal Shark Fishery AGENCY: National Marine Fisheries Service (NMFS... coastal sharks in the State waters of New Jersey. NMFS canceled the moratorium, as required by...

  4. 75 FR 22103 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; Atlantic Coastal Shark Fishery

    Science.gov (United States)

    2010-04-27

    ... Register (75 FR 9158, March 1, 2010). NMFS received one comment in response to that notice. The comment... Management Act Provisions; Atlantic Coastal Shark Fishery AGENCY: National Marine Fisheries Service (NMFS... Atlantic Coastal Sharks (Plan) and that the measures New Jersey has failed to implement and enforce...

  5. 77 FR 35357 - Atlantic Highly Migratory Species; Commercial Atlantic Region Non-Sandbar Large Coastal Shark...

    Science.gov (United States)

    2012-06-13

    ...-Stevens Fishery Conservation and Management Act (16 U.S.C. 1801 et seq.). On January 24, 2012 (77 FR 3393... rule implementing the Atlantic HMS electronic dealer ] reporting system (76 FR 37750; June 28, 2011) or...; Commercial Atlantic Region Non-Sandbar Large Coastal Shark Fishery Opening Date AGENCY: National...

  6. 78 FR 65974 - Atlantic Highly Migratory Species; Advisory Panel for Atlantic Highly Migratory Species Southeast...

    Science.gov (United States)

    2013-11-04

    ... not limited to data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean... information, including but not limited to data and models, used in stock assessments for oceanic sharks in the... Atlantic oceanic sharks, it may be expanded to include other HMS, as needed. The primary purpose of...

  7. 75 FR 57698 - Atlantic Highly Migratory Species; Atlantic Billfish Management, White Marlin (Kajikia albidus

    Science.gov (United States)

    2010-09-22

    ... manage: Atlantic tunas, listed by species; oceanic sharks; and, Atlantic swordfish, marlin, and sailfish....), oceanic sharks, sailfishes (Istiophorus spp.), and swordfish (Xiphias gladius).'' Prior to the addition of... Sharks (43 FR 3818), which was supported by an Environmental Impact Statement (42 FR 57716)....

  8. 76 FR 57709 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2011-09-16

    .... As outlined in the September 20, 2010, ANPR (75 FR 57235), sharks have been federally managed since... National Oceanic and Atmospheric Administration 50 CFR Part 635 RIN 0648-BA17.e Atlantic Highly Migratory Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS),...

  9. 75 FR 11133 - Fisheries of the South Atlantic; South Atlantic Fishery Management Council; Public Meeting

    Science.gov (United States)

    2010-03-10

    ... Wreckfish Shareholders for the South Atlantic region to discuss draft Amendment 20 to the Snapper Grouper... Shareholders for the South Atlantic region. See SUPPLEMENTARY INFORMATION. DATES: The meeting will take place... Wreckfish Shareholders on changes the Council is considering for the current ITQ program in Amendment 20...

  10. Population genomics reveals seahorses (Hippocampus erectus of the western mid-Atlantic coast to be residents rather than vagrants.

    Directory of Open Access Journals (Sweden)

    J T Boehm

    Full Text Available Understanding population structure and areas of demographic persistence and transients is critical for effective species management. However, direct observational evidence to address the geographic scale and delineation of ephemeral or persistent populations for many marine fishes is limited. The Lined seahorse (Hippocampus erectus can be commonly found in three western Atlantic zoogeographic provinces, though inhabitants of the temperate northern Virginia Province are often considered tropical vagrants that only arrive during warm seasons from the southern provinces and perish as temperatures decline. Although genetics can locate regions of historical population persistence and isolation, previous evidence of Virginia Province persistence is only provisional due to limited genetic sampling (i.e., mitochondrial DNA and five nuclear loci. To test alternative hypotheses of historical persistence versus the ephemerality of a northern Virginia Province population we used a RADseq generated dataset consisting of 11,708 single nucleotide polymorphisms (SNP sampled from individuals collected from the eastern Gulf of Mexico to Long Island, NY. Concordant results from genomic analyses all infer three genetically divergent subpopulations, and strongly support Virginia Province inhabitants as a genetically diverged and a historically persistent ancestral gene pool. These results suggest that individuals that emerge in coastal areas during the warm season can be considered "local" and supports offshore migration during the colder months. This research demonstrates how a large number of genes sampled across a geographical range can capture the diversity of coalescent histories (across loci while inferring population history. Moreover, these results clearly demonstrate the utility of population genomic data to infer peripheral subpopulation persistence in difficult-to-observe species.

  11. Population Genomics Reveals Seahorses (Hippocampus erectus) of the Western Mid-Atlantic Coast to Be Residents Rather than Vagrants

    Science.gov (United States)

    Boehm, J. T.; Waldman, John; Robinson, John D.; Hickerson, Michael J.

    2015-01-01

    Understanding population structure and areas of demographic persistence and transients is critical for effective species management. However, direct observational evidence to address the geographic scale and delineation of ephemeral or persistent populations for many marine fishes is limited. The Lined seahorse (Hippocampus erectus) can be commonly found in three western Atlantic zoogeographic provinces, though inhabitants of the temperate northern Virginia Province are often considered tropical vagrants that only arrive during warm seasons from the southern provinces and perish as temperatures decline. Although genetics can locate regions of historical population persistence and isolation, previous evidence of Virginia Province persistence is only provisional due to limited genetic sampling (i.e., mitochondrial DNA and five nuclear loci). To test alternative hypotheses of historical persistence versus the ephemerality of a northern Virginia Province population we used a RADseq generated dataset consisting of 11,708 single nucleotide polymorphisms (SNP) sampled from individuals collected from the eastern Gulf of Mexico to Long Island, NY. Concordant results from genomic analyses all infer three genetically divergent subpopulations, and strongly support Virginia Province inhabitants as a genetically diverged and a historically persistent ancestral gene pool. These results suggest that individuals that emerge in coastal areas during the warm season can be considered “local” and supports offshore migration during the colder months. This research demonstrates how a large number of genes sampled across a geographical range can capture the diversity of coalescent histories (across loci) while inferring population history. Moreover, these results clearly demonstrate the utility of population genomic data to infer peripheral subpopulation persistence in difficult-to-observe species. PMID:25629166

  12. Geologic Provinces of the Arctic, 2000 (prvarcst)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This coverage includes arcs, polygons and polygon labels that describe Arctic portion of the U.S. Geological Survey defined geologic provinces of the World in 2000.

  13. Bacterial assemblages of the eastern Atlantic Ocean reveal both vertical and latitudinal biogeographic signatures

    Directory of Open Access Journals (Sweden)

    C. J. Friedline

    2012-06-01

    Full Text Available Microbial communities are recognized as major drivers of the biogeochemical processes in the oceans. However, the genetic diversity and composition of those communities is poorly understood. The aim of this study is to investigate the composition of bacterial assemblages in three different water layer habitats: surface (2–20 m, deep chlorophyll maximum (DCM; 28–90 m, and deep (100–4600 m at nine stations along the eastern Atlantic Ocean from 42.8° N to 23.7° S. The sampling of three discrete, predefined habitat types from different depths, Longhurstian provinces, and geographical locations allowed us to investigate whether marine bacterial assemblages show spatial variation and to determine if the observed spatial variation is influenced by current environmental conditions, historical/geographical contingencies, or both. The PCR amplicons of the V6 region of the 16S rRNA from 16 microbial assemblages were pyrosequenced, generating a total of 352 029 sequences; after quality filtering and processing, 257 260 sequences were clustered into 2871 normalized operational taxonomic units (OTU using a definition of 97% sequence identity. Community ecology statistical analyses demonstrate that the eastern Atlantic Ocean bacterial assemblages are vertically stratified and associated with water layers characterized by unique environmental signals (e.g., temperature, salinity, and nutrients. Genetic compositions of bacterial assemblages from the same water layer are more similar to each other than to assemblages from different water layers. The observed clustering of samples by water layer allows us to conclude that contemporary environments are influencing the observed biogeographic patterns. Moreover, the implementation of a novel Bayesian inference approach that allows a more efficient and explicit use of all the OTU abundance data shows a distance effect suggesting the influence of historical contingencies on the composition of bacterial

  14. Study on Banana Cooperatives in Hainan Province

    OpenAIRE

    Huang, Huide; ZHANG, Wanzhen; Liu, Enping; Zhang, Xizhu

    2013-01-01

    This paper gives an overview of the distribution, member scale, production and operation of banana cooperatives in Hainan Province, and points out the market risk and natural risk faced by the production of banana cooperatives in Hainan Province. In order to promote the banana cooperatives to form new agricultural management system integrating organization and intensification, this paper puts forth the production and operation recommendations, such as joint production of banana cooperatives, ...

  15. The behaviour of consumer prices across provinces

    OpenAIRE

    Wilkinson, Gordon

    2011-01-01

    Measures of core inflation enable a central bank to distinguish price movements that are transitory and generated by non-monetary events from those that are more permanent and related to prior monetary policy decisions. The author uses standard statistical measures to assess the behaviour of consumer prices across provinces and identify price components with more divergent price patterns. The results indicate that energy, shelter and tobacco prices are the most volatile across provinces. Very...

  16. Ectomycorrhizal Fungi in Jiangsu Province, China

    Institute of Scientific and Technical Information of China (English)

    LIAN Bin; DONG Yuan-Rong; HOU Wei-Guo; TONG Li-Hua; YUAN Sheng

    2007-01-01

    A survey was conducted for about 3 years to study the abundance and diversity of ectomycorrhizal fungi (EMF) in Jiangsu Province, China. The identification of the fungal species was based on the microscopic and macroscopic characteristics of their fruiting bodies. About 126 species of EMF were found in Jiangsu Province. These fungi were largely categorized into three orders (of 121 species), four families (of 96 species), and six genera (of about 86 species).

  17. Intestinal acariasis in Anhui Province

    Institute of Scientific and Technical Information of China (English)

    Chao-Pin Li; Jian Wang

    2000-01-01

    The mites found in stored food and house comprise a large group of subclass Acari, belonging to the suborder Acardida of the order Acarifornes. They can be found in dust and vacuum samples from floors, furniture, mattresses, Chinese herbal medicine, dry fruit, grain, flour, sugar, and bedding. These mites are nidicolous and feed on organic debris, including sloughed human skin, fungi, spilled food, pollen, etc. These mites are particularly prevalent in Chinese herbal medicine, dry fruit, grain, flour, sugar, beds, though carpeted floors near beds or couches may also have large numbers. The most common species are Acarus siro, Tyrophagus putrescentiae , Dermatophagoides farinae , D . pteronyssinus, Glycyphagus domesticus, G. Ornatus, Carpoglyphus lactis and Tarsonemus granarius, etc. The viability of mites in storage is quite strong and they can invade and parasitize the intestines of humans[1 -15]. They can cause pulmonary acariasis[16-25] , urinary acariasis[26-33] and so on. The dejecta of mites is a quite strong allergen and can cause different allergic diseases[34-44]. Intestinal acariasis can be caused by some mites related to the way of diet intake and invading against intestinal mucosa, intestinal muscle[45-5a]. The first report of intestinal acariasis caused by these mites was made by Hinman et al (1934)[45]. From then on, all kinds of studies on the disease have been reported gradually. In order to make an epidemiological survey of intestinal acariasis the investigation of the disease was taken in some areas of Anhui Province from 1989 to 1996.

  18. Odonata collected in Hainan and Guangdong Provinces, China in 2014

    OpenAIRE

    Garrison, Rosser W.; Cordero-Rivera, Adolfo; Zhang, Haomiao

    2015-01-01

    A three week trip to Hainan and Guangdong provinces was conducted between 26 May and 11 June 2014, sampling odonates within the vicinity of Diaoluoshan National Nature Reserve, Shuimanxing Village (both Hainan Province) and Nankunshan Nature Reserve (Guangdong Province). Additionally, Cordero and Zhang collected at Shuimanxing Village between 13 and 23 June. A total of 103 species in 78 genera were found for Hainan Province and 51 species in 42 genera in Guangdong Province. Lists of all spec...

  19. Nature and Environment of the Hainan Province of China

    OpenAIRE

    MO,TINGHUI

    2009-01-01

    Hainan island enjoys a long history, but Hainan province is the youngest province of the People's Republic of China. The province has the smallest land area but the biggest ocean area of any province in China. As the largest island of Hainan province, Hainan island, like a pearl, is mounted in the vast blue water of South China Sea. With tropical resort resources, Hainan island has radiant sunshine, soft sandy beaches, blowing sea breeze, the relaxing and healthy spa, wonderful folkways of mi...

  20. An ethnobotanical survey on hormozgan province, Iran

    Directory of Open Access Journals (Sweden)

    Omid Safa

    2012-12-01

    Full Text Available Objective: The present study is based on an ethnobotanical research project conducted in Hormozgan province that is located in south of Iran, bordering waters of the Persian Gulf and Oman Sea. This survey was carried out in order to recover the ethnobotanical and ethnomedicinal knowledge of the residents of this province. They are using medicinal and functional plants for treating or preventing several diseases. Materials and Methods: Ethnobotanical data sheets were run with the native inhabitants and people of the province by arranging frequent field trips to different parts of the province and direct interviews with them especially those who were more familiar with the plants and their usage.Results: A total of 150 plant species belonging to 53 families were recorded for their ethnobotanical and ethnomedicinal uses among the people of province. The records were developed by scientific names, family names, local names, medicinal parts used, different ways of their application, and traditional uses of the plants. There was high compliance in the use of plants in painful disorders, gastrointestinal, and dermatological diseases.Conclusion: This study revealed that the people of Hormozgan province have a rich knowledge of natural resources. The use and consumption of medicinal plants are still important parts of their life. Rational use of native medicinal plants may benefit and improve their living standards and quality of life. The results of this study can be used as a basis for selecting herbs for further pharmacological, phytochemical, and pharmacognostical studies.

  1. Long-term landscape evolution of the South Atlantic passive continental margin along the Kaoko- and Damara Belts, NW-Namibia

    Science.gov (United States)

    Menges, Daniel; Glasmacher, Ulrich Anton; Hackspacher, Peter; Schneider, Gabriele; Salomon, Eric

    2015-04-01

    The Kaoko Belt in northwestern Namibia originates in the collision of the Rio de la Plata and Kongo Craton during the Pan-African Orogeny in the Neoproterozoic (1) and represents the northern arm of the Damara Orogen. NW-Namibias continental crust mainly consists of the NE-SW striking intracontinental branch of the Pan-African Damara mobile belt, which separates the Congo from the Kalahari craton. The Damara Orogen is divided into several tectonostratigraphic zones that are bounded by steeply dipping, ductile shear zones. These regional lineaments can be traced at least 150 km offshore (2). The lithostratigraphic units consist of Proterozoic and Cambrian metamorphosed rocks (534 (7) Ma - 481 (25) Ma (3) as well as Mesozoic sedimentary and igneous rocks. From Permo-Carboniferous to Mid Jurassic northern Namibia was affected by deep erosion of the Damara Orogen, Permo-Triassic collisional processes along the southern margin of Gondwana and eastern margin of Africa (4), and the deposition of the Nama Group sediments and the Karoo megasequence (5). Between the Otjihorongo and the Omaruru Lineament-Waterberg Thrust early Mesozoic tectonic activity is recorded by coarse clastic sediments deposited within NE trending half-graben structures. The Early Jurassic Karoo flood basalt lavas erupted rapidly at 183±1 Ma (6). The Early Cretaceous Paraná-Etendeka flood basalts (132±1 Ma) and mafic dike swarms mark the rift stage of the opening of the South Atlantic (7). Early Cretaceous alkaline intrusions (137-124 Ma) occur preferentially along Mesozoic half-graben structures and are called the Damaraland Igneous Province (8). Late Cretaceous alkaline intrusions and kimberlite pipes occur in northern Namibia. Post Early Paleocene siliciclastic sedimentation in Namibia was largely restricted to a 150 km wide zone (9) and is represented by the Tsondab Sandstone Formation (~ 300 m thickness). The oldest part has an age of early Paleocene and the upper part span from middle Miocene

  2. Coronitic metagabbro and eclogite from the Grenville Province of western Quebec: interpretation of U-Pb geochronology and metamorphism

    Energy Technology Data Exchange (ETDEWEB)

    Indares, A.; Dunning, G. [Memorial Univ. of Newfoundland, Dept. of Earth Sciences, St. John' s, Newfoundland (Canada)]. E-mail: afin@sparky2.esd.mun.ca

    1997-07-15

    We present new U-Pb and metamorphic data on high-pressure coronitic metagabbros from three distinct structural settings in the Parautochthonous belt of the Grenville Province in western Quebec. Intrusive ages are (i) 1217{sub -10}{sup +15} Ma, for metagabbro close to the Grenville Front, correlative with the Sudbury dykes, defined in Ontario; (ii) 1403{sub -11}{sup +14} Ma for an eclogitized lens at the base of the highest structural level (SL4), a new age for mafic magmatism in the western Grenville; and (iii) 1218{sub -34}{sup +53} Ma for metagabbro from SL4, interpreted as correlative with metagabbros from the Algonquin and Shawanaga domains in Ontario. Metamorphism in all cases is Grenvillian, with the best constrained age of 1069 {+-} 3 Ma for the metagabbro of SL4. Metamorphic grade increases from the Grenville Front to the south. The mafic rocks preserve relict igneous textures overprinted by garnet + clinopyroxene that developed as coronas and (or) pseudomorphs after igneous phases. The highest grade metagabbros contain omphacite and some lack primary plagioclase, therefore being eclogites. However, interpretation of textures and mineral chemistry indicates that they were equilibrated during decompression (at 1350 MPa and 720{sup o}C, sample 51: and at 1200 MPa and 740{sup o}C, sample 29), so maximum depths of burial remain unconstrained. Their evolution is interpreted as follows: (i) high-pressure metamorphism by burial of the Laurentian margin under accreted terranes thrust toward the northwest between 1080 and 1060 Ma; (ii) residence at intermediate crustal levels, for a few tens of millions of years; and (iii) rapid exhumation by renewed thrusting that led to the emplacement of the high-pressure units over the northerly adjacent structural units of the Parautochthonous Belt. (author)

  3. Coronitic metagabbro and eclogite from the Grenville Province of western Quebec: interpretation of U-Pb geochronology and metamorphism

    International Nuclear Information System (INIS)

    We present new U-Pb and metamorphic data on high-pressure coronitic metagabbros from three distinct structural settings in the Parautochthonous belt of the Grenville Province in western Quebec. Intrusive ages are (i) 1217-10+15 Ma, for metagabbro close to the Grenville Front, correlative with the Sudbury dykes, defined in Ontario; (ii) 1403-11+14 Ma for an eclogitized lens at the base of the highest structural level (SL4), a new age for mafic magmatism in the western Grenville; and (iii) 1218-34+53 Ma for metagabbro from SL4, interpreted as correlative with metagabbros from the Algonquin and Shawanaga domains in Ontario. Metamorphism in all cases is Grenvillian, with the best constrained age of 1069 ± 3 Ma for the metagabbro of SL4. Metamorphic grade increases from the Grenville Front to the south. The mafic rocks preserve relict igneous textures overprinted by garnet + clinopyroxene that developed as coronas and (or) pseudomorphs after igneous phases. The highest grade metagabbros contain omphacite and some lack primary plagioclase, therefore being eclogites. However, interpretation of textures and mineral chemistry indicates that they were equilibrated during decompression (at 1350 MPa and 720oC, sample 51: and at 1200 MPa and 740oC, sample 29), so maximum depths of burial remain unconstrained. Their evolution is interpreted as follows: (i) high-pressure metamorphism by burial of the Laurentian margin under accreted terranes thrust toward the northwest between 1080 and 1060 Ma; (ii) residence at intermediate crustal levels, for a few tens of millions of years; and (iii) rapid exhumation by renewed thrusting that led to the emplacement of the high-pressure units over the northerly adjacent structural units of the Parautochthonous Belt. (author)

  4. Kinematics of the South Atlantic rift

    Directory of Open Access Journals (Sweden)

    C. Heine

    2013-01-01

    Full Text Available The South Atlantic rift basin evolved as branch of a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. While the relative motions between South America and Africa for post-breakup times are well resolved, many issues pertaining to the fit reconstruction and particular the relation between kinematics and lithosphere dynamics during pre-breakup remain unclear in currently published plate models. We have compiled and assimilated data from these intraplated rifts and constructed a revised plate kinematic model for the pre-breakup evolution of the South Atlantic. Based on structural restoration of the conjugate South Atlantic margins and intracontinental rift basins in Africa and South America, we achieve a tight fit reconstruction which eliminates the need for previously inferred large intracontinental shear zones, in particular in Patagonian South America. By quantitatively accounting for crustal deformation in the Central and West African rift zone, we have been able to indirectly construct the kinematic history of the pre-breakup evolution of the conjugate West African-Brazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic Pre-salt sag basin and the São Paulo High. We model an initial E–W directed extension between South America and Africa (fixed in present-day position at very low extensional velocities until Upper Hauterivian times (≈126 Ma when rift activity along in the equatorial Atlantic domain started to increase significantly. During this initial ≈17 Myr-long stretching episode the Pre-salt basin width on the conjugate Brazilian and West African margins is generated. An intermediate stage between 126.57 Ma and Base Aptian is characterised by strain localisation, rapid lithospheric weakening in the

  5. Zircon U-Pb ages and geochemistry of igneous and metamorphic rocks in the northern Prince Charles Mountains, Antarctica

    International Nuclear Information System (INIS)

    High-grade metamorphic and felsic igneous rocks from the northern Prince Charles Mountains, East Antarctica, have been characterised geochemically and dated from SHRIMP zircon geochronological data. Around 980 Ma ago, voluminous magmas representing a combination of mantle-derived and intracrustal melts, including orthopyroxene- quartz monzonite ('charnockite') on Loewe Massif and granitic and syenitic intrusions on Mount Collins, were emplaced during a regional high-grade tectonothermal event. Garnet leucogneiss sheets on Mount McCanhy, the products of local partial melting, were also emplaced at about this time. The geology of Fisher Massif is exceptional in that a ca 1280-Ma metavolcanic sequence and coeval granodiorite have been metamorphosed only up to the lower amphibolite facies, and intruded by a ca 1020-Ma biotite granite. None of the analysed samples shows, in its isotopic systematics, the effects of 500-Ma events, prominent elsewhere in East Antarctica. Rare inherited components, 1850-1900 Ma old, were found in some samples. A paragneiss on Mount Meredith yielded 2500-2800-Ma and 1800-2100-Ma detrital zircon populations. (authors)

  6. Nitrous oxide in the North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    S. Walter

    2006-01-01

    Full Text Available In order to get a comprehensive picture of the distribution of nitrous oxide (N2O in the North Atlantic Ocean, measurements of dissolved nitrous oxide were made during three cruises in the tropical, subtropical and cold-temperate North Atlantic Ocean in October/November 2002, March/April 2004, and May 2002, respectively. To account for the history of atmospheric N2O, we suggest a new depth-dependent calculation of excess N2O (ΔN2O. N2O depth profiles showed supersaturation throughout the water column with a distinct increasing trend from the cold-temperate to the tropical region. Lowest nitrous oxide concentrations, near equilibrium and with an average of 11.0±1.7 nmol L−1, were found in the cold-temperate North Atlantic where the profiles showed no clear maxima. Highest values up to 37.3 nmol L−1 occurred in the tropical North Atlantic with clear maxima at approximately 400 m. A positive correlation of nitrous oxide with nitrate, as well as excess nitrous oxide with the apparent oxygen utilization (AOU, was only observed in the subtropical and tropical regions. Therefore, we conclude that the formation of nitrous oxide via nitrification occurs in the tropical region rather than in the cold-temperate region of the North Atlantic Ocean

  7. Origin of enriched components in the South Atlantic: Evidence from 40 Ma geochemical zonation of the Discovery Seamounts

    Science.gov (United States)

    Schwindrofska, Antje; Hoernle, Kaj; Hauff, Folkmar; van den Bogaard, Paul; Werner, Reinhard; Garbe-Schönberg, Dieter

    2016-05-01

    Spatial geochemical zonation is being increasingly recognized in Pacific and Atlantic hotspot tracks and is believed to reflect zonation within plumes upwelling from the margins of the Large Low Shear Velocity Provinces (LLSVPs) at the base of Earth's mantle. We present new 40Ar/39Ar age data for the Discovery Rise (South Atlantic Ocean) that show an age progression in the direction of plate motion from 23 Ma in the southwest to 40 Ma in the northeast of the Rise, consistent with formation of the Rise above a mantle plume. The lavas have incompatible element and Sr-Nd-Pb-Hf radiogenic isotope characteristics similar to the enriched DUPAL anomaly occurring in the southern hemisphere. The northern chain of seamounts is compositionally similar to the adjacent Gough subtrack of the bilaterally-zoned Tristan-Gough hotspot track, whereas the southern chain has some of the most extreme DUPAL compositions found in South Atlantic intraplate lavas thus far. The nearby southern Mid-Atlantic Ridge, believed to interact with the Discovery hotspot, shows a similar spatial geochemical distribution, consistent with the Discovery hotspot being zoned over its entire 40 Ma history. Our study implies a deep origin for the DUPAL anomaly, suggesting recycling of subcontinental lithospheric mantle (± lower crust) and oceanic crust through the lower mantle. The presence of an additional (Southern Discovery) DUPAL-like component, in addition to the Tristan and Gough/Northern Discovery components, in long-term zoned South Atlantic hotspots, points to the presence of a third lower mantle reservoir and thus is not consistent with the simple model that bilaterally-zoned plumes sample a chemically distinct LLSVP and the ambient mantle outside of the LLSVP.

  8. 76 FR 53413 - South Atlantic Fishery Management Council Meeting

    Science.gov (United States)

    2011-08-26

    ... Enforcement Committee; Ecosystem-Based Management Committee; Executive/ Finance Committees; King and Spanish... National Oceanic and Atmospheric Administration RIN 0648-XA660 South Atlantic Fishery Management Council... (NOAA), Commerce. ACTION: Notice of public meeting of the South Atlantic Fishery Management...

  9. Determination of divalent iron content in igneous rocks of ultrabasic, basic and intermediate compositions by a wavelength-dispersive X-ray fluorescence spectrometric method

    International Nuclear Information System (INIS)

    This paper proposes the quantitative wavelength-dispersive X-ray fluorescence (XRF) technique of divalent iron content determination in igneous rocks and reports specifics of this technique in terms of classifying rocks into ultrabasic, basic, intermediate and acid ones. Unlike the widely used technique of titration, the proposed XRF technique does not require a labor-consuming procedure for sample preparation. In the fields of FeKβ5 line, and FeKβ′ and FeKβ″ satellites relative intensities of XRF emission spectrum lines are dependent on the valence state of iron in minerals. The ratio FeKβ5/FeKβ1,3 is preferred as the analytical parameter. The XRF method allows divalent iron content (expressed as FeO oxide) over 1.5% to be measured in igneous rocks of ultrabasic and basic compositions by the common calibration equation with the error below 10 rel. %, that is comparable with the error of titrimetric analysis. The samples of igneous rocks of intermediate composition and granodiorites should be analyzed using calibration equations obtained with certified reference materials corresponding in composition to the study samples. For the samples of alkaline rocks the errors of FeO content determination might be in excess of 50 rel. %. - Highlights: • The wavelength-dispersive X-ray fluorescence method allows the determination of divalent iron contents. • Separate calibrations should be used for different types of igneous rocks. • Errors of X-ray fluorescence method and titrimetric analysis are comparable

  10. Epithermal neutron activation, radiometric, correlation and principal component analysis applied to the distribution of major and trace elements in some igneous and metamorphic rocks from Romania

    Energy Technology Data Exchange (ETDEWEB)

    Cristache, C.I. [National Institute of Research and Development for Physics and Nuclear Engineering Horia-Hulubei, P.O. Box MG-6, 077125 Magurele, Ilfov (Romania); Duliu, O.G. [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele, Ilfov (Romania)], E-mail: duliu@b.astral.ro; Culicov, O.A.; Frontasyeva, M.V. [Joint Institute of Nuclear Research, 6, Joliot Curie str. 141980, Dubna (Russian Federation); Ricman, C. [Geological Institute of Romania, 1 Caransebes Street, 012271 Bucharest (Romania); Toma, M. [National Institute of Research and Development for Physics and Nuclear Engineering Horia-Hulubei, P.O. Box MG-6, 077125 Magurele, Ilfov (Romania)

    2009-05-15

    Six major (Na, Al, K, Ca, Ti, Fe) and 28 trace (Sc, Cr, V, Mn, Co, Zn, Cu, As, Br, Sr, Rb, Zr, Mo, Sn, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Hf, Ta, W, Th and U) elements were determined by epithermal neutron activation analysis (ENAA) in nine Meridional Carpathian and Macin Mountains samples of igneous and metamorphic rocks. Correlation and principal factor analysis were used to interpret data while natural radionuclides radiometry shows a good correlation with ENAA results.

  11. New zircon data supporting models of short-lived igneous activity at 1.89 Ga in the western Skellefte District, central Fennoscandian Shield

    OpenAIRE

    P. Skyttä; Hermansson, T.; Andersson, J.; M. Whitehouse; P. Weihed

    2011-01-01

    New U-Th-Pb zircon data (SIMS) from three intrusive phases of the Palaeoproterozoic Viterliden intrusion in the western Skellefte District, central Fennoscandian Shield, dates igneous emplacement in a narrow time interval at about 1.89 Ga. A locally occurring quartz-plagioclase porphyritic tonalite, here dated at 1889 ± 3 Ma, is considered the youngest of the intrusive units, based on the new age data and field evidence. This supports an existing interpretation of its fault-controlled emplace...

  12. Determination of divalent iron content in igneous rocks of ultrabasic, basic and intermediate compositions by a wavelength-dispersive X-ray fluorescence spectrometric method

    Science.gov (United States)

    Chubarov, Victor M.; Finkelshtein, Alexandr L.

    2015-05-01

    This paper proposes the quantitative wavelength-dispersive X-ray fluorescence (XRF) technique of divalent iron content determination in igneous rocks and reports specifics of this technique in terms of classifying rocks into ultrabasic, basic, intermediate and acid ones. Unlike the widely used technique of titration, the proposed XRF technique does not require a labor-consuming procedure for sample preparation. In the fields of FeKβ5 line, and FeKβ‧ and FeKβ″ satellites relative intensities of XRF emission spectrum lines are dependent on the valence state of iron in minerals. The ratio FeKβ5/FeKβ1,3 is preferred as the analytical parameter. The XRF method allows divalent iron content (expressed as FeO oxide) over 1.5% to be measured in igneous rocks of ultrabasic and basic compositions by the common calibration equation with the error below 10 rel. %, that is comparable with the error of titrimetric analysis. The samples of igneous rocks of intermediate composition and granodiorites should be analyzed using calibration equations obtained with certified reference materials corresponding in composition to the study samples. For the samples of alkaline rocks the errors of FeO content determination might be in excess of 50 rel. %.

  13. Carotenoid dynamics in Atlantic salmon

    Directory of Open Access Journals (Sweden)

    Omholt Stig W

    2006-04-01

    Full Text Available Abstract Background Carotenoids are pigment molecules produced mainly in plants and heavily exploited by a wide range of organisms higher up in the food-chain. The fundamental processes regulating how carotenoids are absorbed and metabolized in vertebrates are still not fully understood. We try to further this understanding here by presenting a dynamic ODE (ordinary differential equation model to describe and analyse the uptake, deposition, and utilization of a carotenoid at the whole-organism level. The model focuses on the pigment astaxanthin in Atlantic salmon because of the commercial importance of understanding carotenoid dynamics in this species, and because deposition of carotenoids in the flesh is likely to play an important life history role in anadromous salmonids. Results The model is capable of mimicking feed experiments analyzing astaxanthin uptake and retention over short and long time periods (hours, days and years under various conditions. A sensitivity analysis of the model provides information on where to look for possible genetic determinants underlying the observed phenotypic variation in muscle carotenoid retention. Finally, the model framework is used to predict that a specific regulatory system controlling the release of astaxanthin from the muscle is not likely to exist, and that the release of the pigment into the blood is instead caused by the androgen-initiated autolytic degradation of the muscle in the sexually mature salmon. Conclusion The results show that a dynamic model describing a complex trait can be instrumental in the early stages of a project trying to uncover underlying determinants. The model provides a heuristic basis for an experimental research programme, as well as defining a scaffold for modelling carotenoid dynamics in mammalian systems.

  14. 78 FR 61844 - North Atlantic Coast Comprehensive Study

    Science.gov (United States)

    2013-10-04

    ... Department of the Army; Corps of Engineers North Atlantic Coast Comprehensive Study AGENCY: Department of the... Atlantic Coast Comprehensive Study (Hurricane Sandy). The USACE is preparing a report that will be submitted to Congress in 2015. The goals of the North Atlantic Coast Comprehensive Study authorized...

  15. Biophysical regions identification using an artificial neuronal network: A case study in the South Western Atlantic

    Science.gov (United States)

    Saraceno, Martin; Provost, Christine; Lebbah, Mustapha

    A classification method based on an artificial neuronal network is used to identify biophysical regions in the South Western Atlantic (SWA). The method comprises a probabilistic version of the Kohonen’s self-organizing map and a Hierarchical Ascending Clustering algorithm. It objectively defines the optimal number of classes and the class boundaries. The method is applied to ocean surface data provided by satellite: chlorophyll-a, sea surface temperature and sea surface temperature gradient, first to means and then, in an attempt to examine seasonal variations, to monthly climatologies. Both results reflect the presence of the major circulation patterns and frontal positions in the SWA. The provinces retrieved using mean fields are compared to previous results and show a more accurate description of the SWA. The classification obtained with monthly climatologies offers the flexibility to include the time dimension; the boundaries of biophysical regions established are not fixed, but vary in time. Perspectives and limitations of the methodology are discussed.

  16. CARINA alkalinity data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    A. Velo

    2009-08-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic.

    These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these, 75 cruises report alkalinity values.

    Here we present details of the secondary QC on alkalinity for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the alkalinity values for 16 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal accuracy of the CARINA-ATL alkalinity data to be 3.3 μmol kg−1. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  17. CARINA: nutrient data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    T. Tanhua

    2009-07-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic. These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these 84 cruises report nitrate values, 79 silicate, and 78 phosphate. Here we present details of the secondary QC for nutrients for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the nutrient values for 43 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004. Based on our analysis we estimate the internal accuracy of the CARINA-ATL nutrient data to be: nitrate 1.5%; phosphate 2.6%; silicate 3.1%. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  18. Millennial changes in North Atlantic oxygen concentrations

    Science.gov (United States)

    Hoogakker, B. A. A.; Thornalley, D. J. R.; Barker, S.

    2016-01-01

    Glacial-interglacial changes in bottom water oxygen concentrations [O2] in the deep northeast Atlantic have been linked to decreased ventilation relating to changes in ocean circulation and the biological pump (Hoogakker et al., 2015). In this paper we discuss seawater [O2] changes in relation to millennial climate oscillations in the North Atlantic over the last glacial cycle, using bottom water [O2] reconstructions from 2 cores: (1) MD95-2042 from the deep northeast Atlantic (Hoogakker et al., 2015) and (2) ODP (Ocean Drilling Program) Site 1055 from the intermediate northwest Atlantic. The deep northeast Atlantic core MD95-2042 shows decreased bottom water [O2] during millennial-scale cool events, with lowest bottom water [O2] of 170, 144, and 166 ± 17 µmol kg-1 during Heinrich ice rafting events H6, H4, and H1. Importantly, at intermediate depth core ODP Site 1055, bottom water [O2] was lower during parts of Marine Isotope Stage 4 and millennial cool events, with the lowest values of 179 and 194 µmol kg-1 recorded during millennial cool event C21 and a cool event following Dansgaard-Oeschger event 19. Our reconstructions agree with previous model simulations suggesting that glacial cold events may be associated with lower seawater [O2] across the North Atlantic below ˜ 1 km (Schmittner et al., 2007), although in our reconstructions the changes are less dramatic. The decreases in bottom water [O2] during North Atlantic Heinrich events and earlier cold events at the two sites can be linked to water mass changes in relation to ocean circulation changes and possibly productivity changes. At the intermediate depth site a possible strong North Atlantic Intermediate Water cell would preclude water mass changes as a cause for decreased bottom water [O2]. Instead, we propose that the lower bottom [O2] there can be linked to productivity changes through increased export of organic material from the surface ocean and its subsequent remineralization in the water column

  19. 75 FR 27219 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Science.gov (United States)

    2010-05-14

    ... United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications...), Commerce. ACTION: Final rule. SUMMARY: NMFS issues final specifications for the 2010 Atlantic deep- sea red... document is also accessible via the Internet at http://www.nefmc.org . NMFS prepared a Final...

  20. Pervalence of intestinal parasites in Ordu province

    Directory of Open Access Journals (Sweden)

    Ülkü Karaman

    2014-06-01

    Full Text Available Objective: The epidemiology of intestinal parasites vary according to country’s geographic location, sociocultural structure and diet. An epidemiological study of intestinal parasites has not been observed in Ordu Province and around. The aim of this study was determining the intestinal parasites data of Ordu Provincial Health Directorate retrosrectively. Methods: Between January 2006 and December 2013 the data of the provinceal Health Directorate of Ordu were retrospectively evaluated. Results: 7194 positivity has been reported in the study. Quantitative distribution of the parasites were as follows; 3415 Enterobius vermicularis, 2802 Ascaris lumbricoides, 1182 Entamoeba histolytica, 705 Giardia intestinalis, 682 Taenia spp, 245 Hookworm infection, 22 Trichuris trichiura, 17 Fasciola hepatica and 12 Strongiloides stercoralis. Conclusion: As a result intestinal parasites in Ordu Province is a major public health problem.

  1. Differentiation of pre-existing trapped methane from thermogenic methane in an igneous-intruded coal by hydrous pyrolysis

    Science.gov (United States)

    Dias, Robert F.; Lewan, Michael D.; Birdwell, Justin E.; Kotarba, Maciej J.

    2014-01-01

    So as to better understand how the gas generation potential of coal changes with increasing rank, same-seam samples of bituminous coal from the Illinois Basin that were naturally matured to varying degrees by the intrusion of an igneous dike were subjected to hydrous pyrolysis (HP) conditions of 360 °C for 72 h. The accumulated methane in the reactor headspace was analyzed for δ13C and δ2H, and mol percent composition. Maximum methane production (9.7 mg/g TOC) occurred in the most immature samples (0.5 %Ro), waning to minimal methane values at 2.44 %Ro (0.67 mg/g TOC), and rebounding to 3.6 mg/g TOC methane in the most mature sample (6.76 %Ro). Methane from coal with the highest initial thermal maturity (6.76 %Ro) shows no isotopic dependence on the reactor water and has a microbial δ13C value of −61‰. However, methane from coal of minimal initial thermal maturity (0.5 %Ro) shows hydrogen isotopic dependence on the reaction water and has a δ13C value of −37‰. The gas released from coals under hydrous pyrolysis conditions represents a quantifiable mixture of ancient (270 Ma) methane (likely microbial) that was generated in situ and trapped within the rock during the rapid heating by the dike, and modern (laboratory) thermogenic methane that was generated from the indigenous organic matter due to thermal maturation induced by hydrous pyrolysis conditions. These findings provide an analytical framework for better assessment of natural gas sources and for differentiating generated gas from pre-existing trapped gas in coals of various ranks.

  2. Temperature effects on kerogen and on molecular and isotopic composition of organic matter in Pierre Shale near an igneous dike

    Science.gov (United States)

    Clayton, J.L.; Bostick, N.H.

    1986-01-01

    A suite of siltstone samples from the Upper Cretaceous Pierre Shale from the contact zone of a 130-cm thick igneous dike near Wolcott, Colorado, U.S.A., was taken from the contact to 170 cm from the dike to study the effects of temperature on the organic matter. The sampled bedding interval was about 10 cm thick, so variation in lithology and type of organic matter is minimal. Vitrinite reflectance values (R0) increase from 0.4 far from the dike, to 3.3% near the dike contact. Geochemical measurements show systematic thermal effects analogous to those often observed for catagenesis and metagenesis in the depth range of 1-4 km within a sedimentary basin. The H/C ratio of kerogen and the hydrogen index (Rock-Eval) decrease most rapidly in the 0.6-1.7% R0 range, in which the transformation ratio (Rock-Eval) increases from 0.1 to 0.3. Based on extraction of C15+ compounds, the main increase of hydrocarbons and total extractable organic matter occurs between 0.6 and 1.0% reflectance. The saturated/aromatic hydrocarbon ratio increases almost twofold in this range of maturity. However, the pristane/phytane ratio is essentially constant through the hydrocarbon generation zone but decreases slightly at high levels of thermal alteration (R0 > 1.2%). The ??13C values for aromatic and saturated hydrocarbons are about -27 and -29???, respectively, and are constant to about 1.0% R0, then both become heavier by about 2??? at higher R0 values. ?? 1986.

  3. Distribution of chemical elements in calc-alkaline igneous rocks, soils, sediments and tailings deposits in northern central Chile

    Science.gov (United States)

    Oyarzún, Jorge; Oyarzun, Roberto; Lillo, Javier; Higueras, Pablo; Maturana, Hugo; Oyarzún, Ricardo

    2016-08-01

    This study follows the paths of 32 chemical elements in the arid to semi-arid realm of the western Andes, between 27° and 33° S, a region hosting important ore deposits and mining operations. The study encompasses igneous rocks, soils, river and stream sediments, and tailings deposits. The chemical elements have been grouped according to the Goldschmidt classification, and their concentrations in each compartment are confronted with their expected contents for different rock types based on geochemical affinities and the geologic and metallogenic setting. Also, the element behavior during rock weathering and fluvial transport is here interpreted in terms of the ionic potentials and solubility products. The results highlight the similarity between the chemical composition of the andesites and that of the average Continental Crust, except for the higher V and Mn contents of the former, and their depletion in Mg, Ni, and Cr. The geochemical behavior of the elements in the different compartments (rocks, soils, sediments and tailings) is highly consistent with the mobility expected from their ionic potentials, their sulfates and carbonates solubility products, and their affinities for Fe and Mn hydroxides. From an environmental perspective, the low solubility of Cu, Zn, and Pb due to climatic, chemical, and mineralogical factors reduces the pollution risks related to their high to extremely high contents in source materials (e.g., rocks, altered zones, tailings). Besides, the complex oxyanions of arsenic get bound by colloidal particles of Fe-hydroxides and oxyhydroxides (e.g., goethite), thus becoming incorporated to the fine sediment fraction in the stream sediments.

  4. Fractionation and magma mixing within intruding dike swarm: evidence from the Miocene Shitara-Otoge igneous complex, central Japan

    Science.gov (United States)

    Geshi, Nobuo

    2000-05-01

    The analysis of intrusion pattern and petrological character of the central dike swarm in the Miocene igneous complex of the Shitara district, central Japan clarified that magma mixing between a strongly differentiated magma and a less-differentiated magma occurred within a dike swarm. The dike rocks have a wide compositional variation ranging from 5.5 to 0.7 wt.% MgO. They are divided into P1- and P2-types. The P2-type rocks provide many lines of evidence for magma mixing such as reversely zoned phenocrysts, bimodal composition distribution, and dissolution texture, whereas P1-type rocks do not. Phenocryst compositions of P2-type suggest that the magma mixing occurred between a less-fractionated phenocryst-poor magma and a strongly fractionated crystal-rich magma. Concentration ratios among incompatible elements show that the mixing end components were derived from a similar parental magma common to P1-type by fractional crystallization in a near closed system. The dikes with evidence for the magma mixing (P2-type) are distributed only in the southern marginal part of the dike swarm, whereas P1-type dikes do not show any such localization. The distribution and the intrusion direction of the dikes indicate a nearly horizontal outward flow of magmas in the southern part of the dike swarm and accompanied magma mixing in the dike during intrusion. The fractionated end component is inferred to be a product of crystal fractionation within small and ephemeral magma pockets in the dike swarm. Magma mixing is thought to have occurred when a newly intruded dike ruptured the magma reservoir. The frequency of magma mixing was controlled mainly by competition between the lifetime of ephemeral magma reservoir and frequency of dike intrusions. The condition of magma mixing was satisfied only in the southern part of the dike swarm affected by the preceding volcanic activities.

  5. Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igneous Complex, South Africa

    Science.gov (United States)

    Hirsikko, A.; Vakkari, V.; Tiitta, P.; Manninen, H. E.; Gagné, S.; Laakso, H.; Kulmala, M.; Mirme, A.; Mirme, S.; Mabaso, D.; Beukes, J. P.; Laakso, L.

    2012-05-01

    South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring and being processed in a large geological structure termed the Bushveld Igneous Complex (BIC). The area is also highly populated by informal, semi-formal and formal residential developments. However, knowledge of air quality and research related to the atmosphere is still very limited in the area. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distributions and number concentrations, together with meteorological parameters, trace gases and particulate matter (PM) were measured for over two years at Marikana in the heart of the western BIC. The observations showed that trace gas (i.e. SO2, NOx, CO) and black carbon concentrations were relatively high, but in general within the limits of local air quality standards. The area was characterised by very high condensation sink due to background aerosol particles, PM10 and O3 concentration. The results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO2-based nucleation followed by the growth by condensation of vapours from industrial, residential and natural sources was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. The air mass back trajectory and wind direction analyses showed that the secondary particle formation was influenced both by local and regional pollution and vapour sources. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during nucleation events were similar to results previously published for a semi

  6. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    Science.gov (United States)

    Dewit, M. J.

    1986-01-01

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  7. Uranium provinces and the exploration industry

    International Nuclear Information System (INIS)

    There is little doubt that exploration by mining companies in established districts or 'provinces' has led to the discovery of substantial additional ore reserves. However, the competition for, and expenses of, land acquisitions in these known districts often prompts companies to search further afield. In some cases, new discoveries can merely be regarded as extensions of known provinces while others are located in completely new areas. Whether the explorers utilized concepts of metallogenic provinces in the course of such discoveries is questionable; rather, they would have sought the particular combinations of geological circumstances required by the model. Once a new deposit is found, however, the concept of a province, whether correct in that situation or not, is usually responsible for stimulating further activity. Recent examples of such behaviour are the Arizona Strip and NE Nebraska (USA) in provincial extensions and Roxby Downs, Lone Gull (NW Territories, Australia) and Lagoa Real (Brazil) in new areas. More routine and scientific application of metallogenic province theory by the uranium exploration industry would require evidence that not only the bulk of the world's uranium reserves but also the majority of the individual world-class deposits fall into geologically definable provinces. Such evidence should include the demonstration that particular areas of the Earth's crust had been enriched in uranium (with or without related elements) and that this enrichment had persisted through periods of crustal reworking and been responsible for concentrations of the metal ore deposits. The evidence described in the volume is critically reviewed in this context. (author). Refs, 4 figs

  8. Phytoplankton biovolume is independent from the slope of the size spectrum in the oligotrophic atlantic ocean

    KAUST Repository

    Moreno-Ostos, Enrique

    2015-08-06

    Modelling the size-abundance spectrum of phytoplankton has proven to be a very useful tool for the analysis of physical-biological coupling and the vertical flux of carbon in oceanic ecosystems at different scales. A frequent observation relates high phytoplankton biovolume in productive regions with flatter spectrum slope and the opposite in oligotrophic ecosystems. Rather than this, the relationship between high biovolume phytoplankton assemblages and flatter size-abundance spectra does not correspond with measurements of the phytoplankton community in the Atlantic Ocean open waters. As part of the Malaspina Circunnavegation Expedition, sixty seven sampling stations within the Atlantic Ocean covering six oceanographic provinces, at different seasons, produced a complete set of phytoplankton size-spectra whose slope and biovolume did not show any obvious interrelation. In these oligotrophic sites, small (procaryotes) and medium-size (nanoplankton) cells are responsible for the most part of biovolume, and their response to environmental conditions does not apply to changes in the size-abundance spectrum slope as expected in richer, large-cell dominated ecosystems.

  9. Study on Banana Cooperatives in Hainan Province

    Institute of Scientific and Technical Information of China (English)

    Huide; HUANG; Wanzhen; ZHANG; Enping; LIU; Xizhu; ZHANG

    2013-01-01

    This paper gives an overview of the distribution,member scale,production and operation of banana cooperatives in Hainan Province,and points out the market risk and natural risk faced by the production of banana cooperatives in Hainan Province. In order to promote the banana cooperatives to form new agricultural management system integrating organization and intensification,this paper puts forth the production and operation recommendations,such as joint production of banana cooperatives,timely planting of banana,brand management,and improvement of production and operation technical level.

  10. Petrophysical models of high velocity lower crust on the South Atlantic rifted margins: whence the asymmetry?

    Science.gov (United States)

    Trumbull, Robert B.; Franke, Dieter; Bauer, Klaus; Sobolev, Stephan V.

    2015-04-01

    Lower crustal bodies with high seismic velocity (Vp > 7km/s) underlie seaward-dipping reflector wedges on both margins of the South Atlantic, as on many other volcanic rifted margins worldwide. A comprehensive geophysical study of the South Atlantic margins by Becker et al. (Solid Earth, 5: 1011-1026, 2014) showed a strong asymmetry in the development of high-velocity lower crust (HVLC), with about 4 times larger volumes of HVLC on the African margin. That study also found interesting variations in the vertical position of HVLC relative to seaward-dipping reflectors which question a simple intrusive vs. extrusive relationship between these lower- and upper crustal features. The asymmetry of HVLC volumes on the conjugate margins is paradoxically exactly the opposite to that of surface lavas in the Paraná-Etendeka flood basalt province, which are much more voluminous on the South American margin. This contribution highlights the asymmetric features of magma distribution on the South Atlantic margins and explores their geodynamic significance. Petrophysical models of the HVLC are presented in the context of mantle melt generation, based on thickness-velocity (H-Vp) relations. These suggest that the greater volumes and average Vp values of HVLC on the African margin are due to active upwelling and high temperature, whereas passive upwelling under a thick lithospheric lid suppressed magma generation on the South American margin. The contrast in mantle upwelling rate and lithospheric thickness on the two margins predictably causes differential uplift, and this may help explain the greater accomodation space for surface lavas on the South American side although melt generation was strongest under the African margin.

  11. Response of the South Atlantic circulation to an abrupt collapse of the Atlantic meridional overturning circulation

    Energy Technology Data Exchange (ETDEWEB)

    Laurian, Audine [University of Hawai' i at Manoa, International Pacific Research Center, School of Ocean and Earth Science and Technology, Honolulu, HI (United States); Drijfhout, Sybren S. [Royal Netherlands Meteorological Institute, De Bilt (Netherlands)

    2011-08-15

    The South Atlantic response to a collapse of the North Atlantic meridional overturning circulation (AMOC) is investigated in the ECHAM5/MPI-OM climate model. A reduced Agulhas leakage (about 3.1 Sv; 1 Sv = 10{sup 6} m{sup 3} s{sup -1}) is found to be associated with a weaker Southern Hemisphere (SH) supergyre and Indonesian throughflow. These changes are due to reduced wind stress curl over the SH supergyre, associated with a weaker Hadley circulation and a weaker SH subtropical jet. The northward cross-equatorial transport of thermocline and intermediate waters is much more strongly reduced than Agulhas leakage in relation with an AMOC collapse. A cross-equatorial gyre develops due to an anomalous wind stress curl over the tropics that results from the anomalous sea surface temperature gradient associated with reduced ocean heat transport. This cross-equatorial gyre completely blocks the transport of thermocline waters from the South to the North Atlantic. The waters originating from Agulhas leakage flow somewhat deeper and most of it recirculates in the South Atlantic subtropical gyre, leading to a gyre intensification. This intensification is consistent with the anomalous surface cooling over the South Atlantic. Most changes in South Atlantic circulation due to global warming, featuring a reduced AMOC, are qualitatively similar to the response to an AMOC collapse, but smaller in amplitude. However, the increased northward cross-equatorial transport of intermediate water relative to thermocline water is a strong fingerprint of an AMOC collapse. (orig.)

  12. Atlantic hurricane activity during the last millennium

    Science.gov (United States)

    Burn, Michael J.; Palmer, Suzanne E.

    2015-08-01

    Hurricanes are a persistent socio-economic hazard for countries situated in and around the Main Development Region (MDR) of Atlantic tropical cyclones. Climate-model simulations have attributed their interdecadal variability to changes in solar and volcanic activity, Saharan dust flux, anthropogenic greenhouse gas and aerosol emissions and heat transport within the global ocean conveyor belt. However, the attribution of hurricane activity to specific forcing factors is hampered by the short observational record of Atlantic storms. Here, we present the Extended Hurricane Activity (EHA) index, the first empirical reconstruction of Atlantic tropical cyclone activity for the last millennium, derived from a high-resolution lake sediment geochemical record from Jamaica. The EHA correlates significantly with decadal changes in tropical Atlantic sea surface temperatures (SSTs; r = 0.68 1854-2008), the Accumulated Cyclone Energy index (ACE; r = 0.90 1851-2010), and two annually-resolved coral-based SST reconstructions (1773-2008) from within the MDR. Our results corroborate evidence for the increasing trend of hurricane activity during the Industrial Era; however, we show that contemporary activity has not exceeded the range of natural climate variability exhibited during the last millennium.

  13. Coccolithophores in the equatorial Atlantic Ocean

    DEFF Research Database (Denmark)

    Kinkel, Hanno; Baumann, K.-H.; Cepek, M.

    2000-01-01

    The present study was initiated to ascertain the significance of coccolithophores as a proxy for paleoceanographic and paleoproductivity studies in the equatorial Atlantic. Data from a range of different samples, from the plankton, surface sediments as well as sediment cores are shown and compare...

  14. Population structure of Atlantic Mackerel (Scomber scombrus)

    DEFF Research Database (Denmark)

    Jansen, Teunis; Gislason, Henrik

    2013-01-01

    model where the population structure of mackerel is described as a dynamic cline, rather than as connected contingents. Temporal changes in hydrography and mackerel behavior may affect the steepness of the cline at various locations. The new interpretation of the population structure of Atlantic...

  15. MID-ATLANTIC REGIONAL ASSESSMENT: PROJECT DESCRIPTION

    Science.gov (United States)

    As part of the USGCRP's First National Assessment effort, EPA's Global Change Research Program sponsored the first Mid-Atlantic Regional Assessment. A multi-disciplinary team of 14 Pennsylvania State University (Penn State) faculty members led this regional assessment effort.

  16. Oil's not well on the Atlantic frontier

    International Nuclear Information System (INIS)

    This article focuses on the effects of oil exploration on global warming, and discusses Greenpeace's call for the petroleum industry to halt exploration in the Atlantic Frontier, the United Nations Climate Convention which commits governments to work towards the stabilisation of atmospheric greenhouse gas emissions, and the expansion of BP's Solar subsidiary. (UK)

  17. Geologic Provinces of the Caribbean Region, 2004 (prv6bg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset includes a modified subset of polygon features that describe U.S. Geological Survey's defined geologic provinces of the World. Each province has a set...

  18. AtlantOS - Optimizing and Enhancing the Integrated Atlantic Ocean Observing System

    Science.gov (United States)

    Reitz, Anja; Visbeck, Martin; AtlantOS consortium, the

    2016-04-01

    Atlantic Ocean observation is currently undertaken through loosely-coordinated, in-situ observing networks, satellite observations and data management arrangements of heterogeneous international, national and regional design to support science and a wide range of information products. Thus there is tremendous opportunity to develop the systems towards a fully integrated Atlantic Ocean Observing System consistent with the recently developed 'Framework of Ocean Observing'. The vision of AtlantOS is to improve and innovate Atlantic observing by using the Framework of Ocean Observing to obtain an international, more sustainable, more efficient, more integrated, and fit-for-purpose system. Hence, the AtlantOS initiative will have a long-lasting and sustainable contribution to the societal, economic and scientific benefit arising from this integrated approach. This will be delivered by improving the value for money, extent, completeness, quality and ease of access to Atlantic Ocean data required by industries, product supplying agencies, scientist and citizens. The overarching target of the AtlantOS initiative is to deliver an advanced framework for the development of an integrated Atlantic Ocean Observing System that goes beyond the state-of -the-art, and leaves a legacy of sustainability after the life of the project. The legacy will derive from the following aims: i) to improve international collaboration in the design, implementation and benefit sharing of ocean observing, ii) to promote engagement and innovation in all aspects of ocean observing, iii) to facilitate free and open access to ocean data and information, iv) to enable and disseminate methods of achieving quality and authority of ocean information, v) to strengthen the Global Ocean Observing System (GOOS) and to sustain observing systems that are critical for the Copernicus Marine Environment Monitoring Service and its applications and vi) to contribute to the aims of the Galway Statement on Atlantic

  19. Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Physiographic Provinces

    Science.gov (United States)

    Wieczorek, Michael E.; LaMotte, Andrew E.

    2010-01-01

    This dataset represents the area of each physiographic province (Fenneman and Johnson, 1946) in square meters, compiled for every catchment of NHDPlus for the conterminous United States. The source data are from Fenneman and Johnson's Physiographic Provinces of the United States, which is based on 8 major divisions, 25 provinces, and 86 sections representing distinctive areas having common topography, rock type and structure, and geologic and geomorphic history (Fenneman and Johnson, 1946). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins

  20. Sedimentary rocks Uranium in Cerro Largo Province

    International Nuclear Information System (INIS)

    With the aim of the uranium minerals exploration has been carried out several studies by UTE technicians in Cerro Largo Province from 1968 to 1969. In uranium concentration has been found pyrite, phosphate, iron oxides and manganese in uranium. Furthermore in La Divisa Ore were studied concentration Uranium enrichment has been studied in La Divisa ore

  1. Payenia volcanic province, southern Mendoza, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina; Holm, Paul Martin; Llambias, Eduardo Jorge

    2013-01-01

    of the slab and the end of the shallow subduction period. The downwarping slab may have generated an enhanced mantle upwelling of both the intraplate and the MORB-like mantle sources. In samples from almost all parts of the Payenia province and in particular many Nevado, Llancanelo and older Payún...

  2. Nontyphoidal Salmonella Infection, Guangdong Province, China, 20121

    Science.gov (United States)

    Huang, Xi; Huang, Qiong; Dun, Zhongjun; Huang, Wei; Wu, Shuyu; Liang, Junhua; Deng, Xiaoling

    2016-01-01

    We used active and passive surveillance to estimate nontyphoidal Salmonella (NTS) infection during 2012 in Guangdong Province, China. Under passive surveillance, for every reported NTS infection, an estimated 414.8 cases occurred annually. Under active surveillance, an estimated 35.8 cases occurred. Active surveillance provides remarkable advantages in incidence estimate. PMID:26982074

  3. Investigation on Atmospheric Corrosiveness in Hainan Province

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    According to the results of four-year exposure tests for carbon steel samples in Hainan province, the influences of meteorological factors and Cl- on atmospheric corrosion were investigated. The feature of atmospheric corrosion in this area was summarized. A corrosive map for the area was drawn. The corrosion products on carbon steel at some typical places were analyzed by XRD and XPS.

  4. Human rabies in Zhejiang Province, China

    Directory of Open Access Journals (Sweden)

    Jiangping Ren

    2015-09-01

    Conclusions: The majority of rabies cases occurred among 40–65-year-old male residents of northern, mid-west, and southeast Zhejiang Province. Further health education is needed to increase the coverage of post-exposure prophylaxis (PEP in people exposed to possible rabid animals and rabies vaccine use in household animals.

  5. Cogeneration opportunities in the maritime provinces

    International Nuclear Information System (INIS)

    With the arrival of natural gas in New Brunswick in November 1999, the province will be faced with new power generation development opportunities in four different categories of power projects. These include industrial self generation (including cogeneration), merchant power plants, power projects to replace aging facilities, and power projects to help meet future environmental needs. New Brunswick's competitive advantage in harnessing the power generation development opportunities lies in the fact that it is close to major electricity markets in Quebec and New England. It also has many available generation sites. The province's many pulp and paper plants with large process steam needs are also ideal candidates for cogeneration. Some of the major competitive advantages of natural gas over coal are its lower operation and maintenance costs, it is thermally more efficient, produces lower emissions to the environment and prices are competitive. One of the suggestions in New Brunswick Power's new restructuring proposal is to unbundle electricity service in the province into generation and transmission and distribution services. Three gas-fired projects have already been proposed for the province. The 284 MW Bayside Power Project at the Courtenay Bay Generating Station is the most advanced

  6. Livestock rabies outbreaks in Shanxi province, China.

    Science.gov (United States)

    Feng, Ye; Shi, Yanyan; Yu, Mingyang; Xu, Weidi; Gong, Wenjie; Tu, Zhongzhong; Ding, Laixi; He, Biao; Guo, Huancheng; Tu, Changchun

    2016-10-01

    Dogs play an important role in rabies transmission throughout the world. In addition to the severe human rabies situation in China, spillover of rabies virus from dogs in recent years has caused rabies outbreaks in sheep, cattle and pigs, showing that there is an increasing threat to other domestic animals. Two livestock rabies outbreaks were caused by dogs in Shanxi province, China from April to October in 2015, resulting in the deaths of 60 sheep, 10 cattle and one donkey. Brain samples from one infected bovine and the donkey were determined to be rabies virus (RABV) positive by fluorescent antibody test (FAT) and reverse transcription polymerase chain reaction (RT-PCR). The complete RABV N genes of the two field strains, together with those of two previously confirmed Shanxi dog strains, were amplified, sequenced and compared phylogenetically with published sequences of the N gene of RABV strains from Shanxi and surrounding provinces. All of the strains from Shanxi province grouped closely, sharing 99.6 %-100 % sequence identity, indicating the wide distribution and transmission of dog-mediated rabies in these areas. This is the first description of donkey rabies symptoms with phylogenetic analysis of RABVs in Shanxi province and surrounding regions. The result emphasizes the need for mandatory dog rabies vaccination and improved public education to eradicate dog rabies transmission. PMID:27422397

  7. Morphological and karyotypic differentiation in Caranx lugubris (Perciformes: Carangidae) in the St. Peter and St. Paul Archipelago, mid-Atlantic Ridge

    Science.gov (United States)

    Jacobina, Uedson Pereira; Martinez, Pablo Ariel; Cioffi, Marcelo de Bello; Garcia, José; Bertollo, Luiz Antonio Carlos; Molina, Wagner Franco

    2014-03-01

    Isolated oceanic islands constitute interesting model systems for the study of colonization processes, as several climatic and oceanographic phenomena have played an important role in the history of the marine ichthyofauna. The present study describes the presence of two morphotypes of Caranx lugubris, in the St. Peter and St. Paul Archipelago located in the mid-Atlantic. Morphotypes were compared in regard to their morphological and cytogenetic patterns, using C-banding, Ag-NORs, staining with CMA3/DAPI fluorochromes and chromosome mapping by dual-color FISH analysis with 5S rDNA and 18S rDNA probes. We found differences in chromosome patterns and marked divergence in body patterns which suggest that different populations of the Atlantic or other provinces can be found in the Archipelago of St. Peter and St. Paul.

  8. Thermal effects of the Santa Eulália Plutonic Complex (southern Portugal on the meta-igneous and metasedimentary host rocks

    Directory of Open Access Journals (Sweden)

    Cruz, C.

    2014-12-01

    Full Text Available The Santa Eulália Plutonic Complex (SEPC is a late-Variscan granitic body located in the northern part of the Ossa Morena Zone, a inner zone of the Variscan Iberian Massif. The SEPC host rocks are composed of meta-igneous and metasedimentary units, from Upper Proterozoic to Paleozoic ages, with a NW-SE structure, cross-cut by the SEPC. The SEPC host rocks, with low grade metamorphism show well preserved primary sedimentary or igneous mineralogical, textural and structural features. The thermal effect induced by the SEPC is restricted to the roof pendants. At N and NE of the SEPC, textures and paragenesis resulting from thermal metamorphism, are not related to the SEPC intrusion but to a previous magmatism, controlled by the NW-SE regional anisotropies. The restriction of the thermal effects to the pluton roof may be caused by a combination of several interrelated factors: higher volume of granitic mass, thermal effect by advection of fluids and longer period of prevalence of high thermal conditions. The geochemical study of SEPC host rocks shows the heterogeneous character and diversity of metasedimentary, igneous and meta-igneous rocks. The whole rock geochemical data indicate that all the metasedimentary lithologies derived from an upper continental crustal source and the igneous and meta-igneous rocks show no evidence of metasomatic effects by the SEPC emplacement.El Complejo Plutónico de Santa Eulalia (CPSE es un cuerpo granítico tardi-Varisco situado en la parte norte de la Zona de Ossa Morena, en la zona interior del Macizo Ibérico Varisco. Las rocas encajantes del CPSE están compuestas por unidades meta-ígneas y metasedimentarias, de edades que van desde el Proterozoico Superior hasta el Paleozoico, con una estructura de dirección NW-SE, cortada por el CPSE. Las rocas encanjantes del CPSE, con metamorfismo de bajo grado conservan estructuras, mineralogía y textura primarias. El efecto térmicoinducido por el CPSE se limita a los

  9. Differential response of continental stock complexes of Atlantic salmon (Salmo salar) to the Atlantic Multidecadal Oscillation

    Science.gov (United States)

    Friedland, Kevin D.; Shank, Burton V.; Todd, Christopher D.; McGinnity, Philip; Nye, Janet A.

    2014-05-01

    Atlantic salmon, Salmo salar, in the North Atlantic are managed as a set of population complexes distributed in North America and Europe. In recent years, these complexes have experienced reduced marine survival and many populations within the complexes are at risk, especially those at the southern ends of the species amphi-Atlantic range. Atlantic salmon is an anadromous fish dividing its life history between residence in freshwater and the marine environment. The freshwater portion of the life history includes spawning and the rearing of juveniles where in-river production has tended to be relatively stable, whereas the first year at sea, termed the post-smolt year, is characterized by more variable rates of mortality. Although their habitats are widely separated geographically along the North Atlantic seaboards, strong recruitment coherence exists between North American and European stock complexes. This recruitment coherence is correlated with ocean temperature variation associated with the Atlantic Multidecadal Oscillation (AMO). The North Atlantic Oscillation (NAO) appears to be relatively unimportant as a driver of salmon abundance. The mechanism determining the link between AMO-related thermal variation and abundance appears to differ fundamentally for the two continental stock groupings. Whereas ocean climate variability during the first springtime months of juvenile salmon migration to sea appears to be important to the survival of North American stocks, summer climate variation appears to be central to adult recruitment variation for European stocks. This contrast in seasonal effects appears to be related to the varying roles of predation pressure and size-related mortality on the continental stock complexes. The anticipated warming due to global climate change will impose thermal conditions on salmon populations outside historical context and challenge the ability of many populations to persist.

  10. Regional Tectonic Control of Tertiary Mineralization and Recent Faulting in the Southern Basin-Range Province, an Application of ERTS-1 Data

    Science.gov (United States)

    Bechtold, I. C.; Liggett, M. A.; Childs, J. F.

    1973-01-01

    Research based on ERTS-1 MSS imagery and field work in the southern Basin-Range Province of California, Nevada and Arizona has shown regional tectonic control of volcanism, plutonism, mineralization and faulting. This paper covers an area centered on the Colorado River between 34 15' N and 36 45' N. During the mid-Tertiary, the area was the site of plutonism and genetically related volcanism fed by fissure systems now exposed as dike swarms. Dikes, elongate plutons, and coeval normal faults trend generally northward and are believed to have resulted from east-west crustal extension. In the extensional province, gold silver mineralization is closely related to Tertiary igneous activity. Similarities in ore, structural setting, and rock types define a metallogenic district of high potential for exploration. The ERTS imagery also provides a basis for regional inventory of small faults which cut alluvium. This capability for efficient regional surveys of Recent faulting should be considered in land use planning, geologic hazards study, civil engineering and hydrology.

  11. Zircon ages delimit the provenance of a sand extrudite from the Botucatu Formation in the Paraná volcanic province, Iraí, Brazil.

    Science.gov (United States)

    Pinto, Viter M; Hartmann, Léo A; Santos, João O S; McNaughton, Neal J

    2015-09-01

    Ion microprobe age determinations of 102 detrital zircon crystals from a sand extrudite, Cretaceous Paraná volcanic province, set limits on the origin of the numerous sand layers present in this major flood basalt province. The zircon U-Pb ages reflect four main orogenic cycles: Mesoproterozoic (1155-962 Ma), latest Proterozoic-early Cambrian (808-500 Ma) and two Palaeozoic (Ordovician- 480 to 450 Ma, and Permian to Lower Triassic- 296 to 250 Ma). Two additional small concentrations are present in the Neoarchean (2.8 to 2.6 Ga) and Paleoproterozoic (2.0 to 1.7 Ga). Zircon age peaks closely match the several pulses of igneous activity in the Precambrian Brazilian Shield and active orogeny in Argentina. A main delimitation of the origin of the sand is the absence of zircon ages from the underlying Cretaceous basalts, thus supporting an injectite origin of the sand as an extrudite that emanated from the paleoerg that constitutes the Botucatu Formation. PMID:26312429

  12. Teleconnections of Indian monsoon rainfall with AMO and Atlantic tripole

    Science.gov (United States)

    Krishnamurthy, Lakshmi; Krishnamurthy, V.

    2016-04-01

    The teleconnections between the decadal modes in the Indian monsoon rainfall (IMR) and the North Atlantic sea surface temperature are investigated. The two decadal modes of variability in the North Atlantic, the Atlantic multidecadal oscillation (AMO) and the Atlantic tripole, have opposite relation with the two decadal modes of IMR. The AMO has positive correlation with the monsoon rainfall while the Atlantic tripole has negative correlation. This study has put forward hypotheses for the mechanisms involved in the teleconnections of the AMO and the Atlantic tripole with the IMR. The warm phase of AMO may influence the monsoon through the summer North Atlantic Oscillation (SNAO) and further through the equatorial zonal winds which increase the moisture flow over India by enhancing the southwesterly flow. The warm phase of Atlantic tripole may impact the monsoon through the all-season NAO, leading to decreased moisture flow over India through the equatorial wind pattern. The observed relations between the decadal modes in the North Atlantic and the Indian monsoon are explored in the simulations of National Center for Atmospheric Research Community Climate System Model version 4 (CCSM4) model. Although the model supports the observed decadal teleconnection between the Atlantic Ocean and Indian monsoon, it has limitations in capturing the details of the spatial pattern associated with the teleconnection. The teleconnections of AMO and Atlantic tripole with the Indian monsoon is further demonstrated through an experiment with CCSM4 by decoupling the North Atlantic Ocean. The hypotheses for the mechanisms of the Atlantic teleconnections are also explored in the CCSM4 simulation.

  13. Zircon chemistry and magma mixing, SE China: In-situ analysis of Hf isotopes, Tonglu and Pingtan igneous complexes

    Science.gov (United States)

    Griffin, W. L.; Wang, Xiang; Jackson, S. E.; Pearson, N. J.; O'Reilly, Suzanne Y.; Xu, Xisheng; Zhou, Xinmin

    2002-04-01

    Field relations and whole-rock geochemistry indicate that magma mixing has been important in the genesis of the late Mesozoic I-type igneous complexes at Pingtan and Tonglu in SE China. Morphological and trace-element studies of zircon populations in rocks from each of these complexes have defined several distinct growth stages [Mineral. Mag. (2001)]. In-situ LAM-MC-ICPMS microanalysis shows large variations in 176Hf/ 177Hf (up to 15 ɛHf units) between zircons of different growth stages within a single rock, and between zones within single zircon grains (up to 9 ɛHf units). These variations suggest that each of the observed magmas in both complexes developed through hybridisation of ≥2 magmas with different sources. Although this mixing has produced similar Sr and Nd isotopic compositions in the different rock types of each complex, the zircons have functioned as "tape recorders" and have preserved details of the assembly of the different magmas. In the Tonglu complex the most primitive magma is a mafic monzonite (preserved as enclaves), whose isotopic composition suggests derivation from the lower crust; rhyodacites, rhyolites and quartz diorites reflect the mixing of the monzonite with ≥2 more felsic magmas, derived from older crustal materials. In the Pingtan complex, zircons in a quartz diorite enclave suggest mixing between a crustal magma and a more primitive mantle-derived component. Zircons from granites and granodiorite enclaves indicate mixing between the quartz diorite and more felsic melts with lower 176Hf/ 177Hf. Major changes in 176Hf/ 177Hf correlate with discontinuous changes in the trace-element composition and morphology of the zircons, in particular the development of sector zoning that suggests rapid disequilibrium crystallisation. We suggest that the magma mixing recorded by the changes in 176Hf/ 177Hf occurred during transport in magma conduits. The in-situ analysis of Hf-isotopic stratigraphy in zircons is a new and powerful tool for

  14. Geologic Mapping in Nogal Peak Quadrangle: Geochemistry, Intrusive Relations and Mineralization in the Sierra Blanca Igneous Complex, New Mexico

    Science.gov (United States)

    Goff, F.; Kelley, S. A.; Lawrence, J. R.; Cikowski, C. T.; Krier, D. J.; Goff, C. J.; McLemore, V. T.

    2011-12-01

    Nogal Peak quadrangle is located in the northern Sierra Blanca Igneous Complex (SBIC) and contains most of the White Mountain Wilderness (geologic map is available at http://geoinfo.nmt.edu/publications/maps/geologic/ofgm/details.cfml?Volume=134). The geology of the quad consists of a late Eocene to Oligocene volcanic pile (Sierra Blanca Volcanics, mostly alkali basalt to trachyte) intruded by a multitude of dikes, plugs and three stocks: Rialto, 31.4 Ma (mostly syenite), Three Rivers, ca. 29 to 27 Ma (quartz syenite intruded by subordinate alkali granite), and Bonito Lake, 26.6 Ma (mostly monzonite). Three Rivers stock is partially surrounded by alkali rhyolites that geochemically resemble the alkali granites. The circular shape of the stock and surrounding rhyolites suggests they form the root of a probable caldera. SBIC rocks have compositions typical of those found within the Rocky Mountain alkaline belt and those associated with continental rift zone magmatism. Because the volcanic host rocks are deeply eroded, intrusive relations with the stocks are well exposed. Most contacts at stock margins are near vertical. Roof pendants are common near some contacts and stoped blocks up to 700 m long are found within the Three Rivers stock. Contacts, pendants and stoped blocks generally display some combination of hornfelsing, brecciation, fracturing, faulting and mineralization. Sierra Blanca Volcanics display hydrothermal alteration increasing from argillic in the NW sector of the quad to high-temperature porpylitic near stock margins. Retrograde phyllic alteration occurs within breccia pipes and portions of the stocks. Mineral deposits consist of four types: Placer Au, fissure veins (mostly Ag-Pb-Zn±Au), breccia pipes (Au-Mo-Cu), and porphyry Mo-Cu. A singular pipe on the SW margin of Bonito Lake stock contains sapphire-lazulite-alunite. Although Au has been intermittently mined in the quad since 1865, best production of Au originated around the turn of the last

  15. The impact of igneous bedrock weathering on the Mo isotopic composition of stream waters: Natural samples and laboratory experiments

    Science.gov (United States)

    Voegelin, Andrea R.; Nägler, Thomas F.; Pettke, Thomas; Neubert, Nadja; Steinmann, Marc; Pourret, Olivier; Villa, Igor M.

    2012-06-01

    River waters have been shown to be systematically enriched in the heavy molybdenum (Mo) isotopes when compared to typical granites and basalts, which generally possess Mo isotopic compositions (δMo) of around 0‰. This inconsistency has been used to argue against weathering of crustal rocks as the cause for heavy riverine δMo signatures. Incongruent dissolution of primary bedrock, however, may be an important process by which the anomalous Mo signatures of the river dissolved load are produced. This study therefore investigates the effect of igneous crustal rock weathering on the aquatic δMo signal by comparing stream water and bedrock Mo isotope data to results of bulk rock leach experiments. For this purpose, stream water and bedrock (orthogneiss, granite, basalt), as well as soil and vegetation samples were collected in a small catchment in the French Massif Central. In accordance with the results of earlier studies on riverine Mo, both streams are isotopically heavier (δMo = 0.5-1.1‰) than the typical granites and basalts. The excellent agreement of these data with those of Mo released during experimental leaching of the basalt bedrock (0.6-1.0‰) identifies a predominance of basalt weathering over the stream water Mo geochemistry, while other processes (i.e. soil formation, secondary mineral precipitation and adsorption) are subordinate in this catchment. Given that the basalt bulk rock δMo reflects a value typical for crustal magmatic rocks (ca. 0.1‰), Mo isotope fractionation during the incongruent dissolution of basalt can explain the observed isotopically heavy aquatic Mo signatures. Laser ablation analyses demonstrate that the volumetrically minor magmatic sulfides can be highly enriched in Mo and mass balance calculations identify the sulfide melt inclusions as the principal Mo source for the leach solutions. These data suggest that the magmatic sulfides possess a distinctly heavier δMo signature than the coexisting silicate melt. In this

  16. 916 Ma Pole for southwestern Baltica: palaeomagnetism of the Bjerkreim-Sokndal layered intrusion, Rogaland Igneous Complex, southern Norway

    Science.gov (United States)

    Brown, Laurie L.; McEnroe, Suzanne A.

    2015-10-01

    The Rogaland Igneous Complex (RIC) in southern Norway intruded into post-Sveconorwegian granulite facies crust ˜930 Ma. It includes three massif anorthosites, several small leuconorite bodies and the ˜7 km thick norite-quartz mangerite layered Bjerkreim-Sokndal (BKS) intrusion. The intrusion consists of five rhythmic megaunits created by repeated magma influxes topped by a transition zone and more evolved mangerites and quartz mangerites. Over 70 palaeomagnetic sites have been collected in the BKS, sampling all the megacyclic subunits and overlying mangerites. Remanence within the BKS is held in hemo-ilmenite-only rocks (lower parts of the megacyclic units), mixed hemo-ilmenite and magnetite rocks (upper parts of the lower megacyclic units) and magnetite only rocks in the upper highest megacyclic unit and overlying mangerites. Due to the different oxides present magnetic susceptibility varies over four orders of magnitude with a bimodal distribution (mean susceptibility of 6.4 × 10-3 SI for hemo-ilmenite rocks, and 8.7 × 10-2 SI for magnetite rocks). NRM values do not show a strong bimodal distribution as many of the rocks lacking magnetite have hemo-ilmenite with strong lamellar magnetism; average NRM for the entire suite is 8.83 A m-1. All sites within the cyclic part of the intrusion have stable remanence and produce well-clustered site means. Samples from the upper mangerite rocks, dominated by MD magnetite, are commonly unstable and not all sites provide acceptable data. Mean directions for 66 sites spanning the entire intrusion are I = -73.5°, D = 303.4°, with α95 = 3.7° and k = 24. The resulting pole position is at 35.9°S and 217.9°E, with a palaeolatitude for this part of Baltica of -59.4°. Examination of the magnetic mineralogy combined with geochronology for RIC rocks and cooling rates for the region yields an age of magnetization of 916 Ma. Metamorphic country rocks yield similar directions at least 10 km from the contact, confirming the

  17. The effects of assimilation of country rocks by magmas on 18O/16O and 87Sr/86Sr systematics in igneous rocks

    International Nuclear Information System (INIS)

    Examples of positive correlations between intial 87Sr/86Sr and delta18O have now been shown to be very common in igneous rock series. These data in general require some type of mixing of mantle-derived igneous rocks with high-18O, high-87Sr crustal metamorphic rocks that once resided on or near the Earth's surface, such as sedimentary rocks or hydrothermally altered volcanic rocks. Mixing that involves assimilation of country rocks by magmas, however, is not a simple two-end-member process; heat balance requires appreaciable crystallization of cumulates. In such cases, the isotopic compositions may strongly reflect this open-system behavior and indicate the process of assimilation, whereas the major element chemical compositions of the contaminated magmas will be largely controlled by crystal-melt equilibria and crastallization paths fixed by multicomponent cotectics. A variety of oxygen and strontium isotope mixing curves were therefore calculated for this process of combined assimilation-fractional crystallization. The positions and characteristics of the resultant curves on delta18O-87Sr/86Sr diagrams markedly diverge from simple two end-member mixing relationships. Based on the above, model calculation can be crudely fitted to two igneous rock suites (Adamello and Roccamonfina in Italy), but the shapes of the calculated curves appear to rule out magmatic assimilation as an explanation for most delta18O-87Sr/86Sr correlations discovered so far, including all of those involving calc-alkaline granitic batholiths and andesitic volcanic rocks. The isotopic relationshipfs in such magma types must be inherited from their source regions, resumably reflecting patterns that existed in the parent rocks (or magmas) prior to or during melting. (orig.)

  18. Structural, igneous and metamorphic footprints of Pangea break-up preserved in the subducted Austroalpine continental lithosphere of the European Alps.

    Science.gov (United States)

    Spalla, M. I.; Gosso, G.; Rebay, G.; Roda, M.; Zanoni, D.; Zucali, M.

    2015-12-01

    Although in the Alps a large amount of continental lithosphere from both European (lower plate) and Adriatic (upper plate) continental margins was absorbed in the sub-lithospheric mantle during Alpine subduction, relict metamorphic and igneous imprints of the Variscan convergence and the successive Pangea break-up are preserved in the continental crust of both margins. These pre-Alpine signatures are preserved either in small volumes within the exhumed continental crust slivers of the axial belt or in the Alpine hinterland and foreland crusts that were never reworked in deep-seated conditions. Because of the common occurrence of metamorphic and igneous markers of the Variscan convergence in the pre-Alpine continental crust, the Permian-Triassic high thermal regime, which left widespread metamorphic and igneous imprints, can be interpreted as the effect of lithospheric thinning leading to continental rifting and subsequent Tethyan ocean opening. In addition, even Permian igneous activity and related basin formation may be interpreted as linked to lithospheric extension leading to the Pangaea break-up and to subsequent oceanization, predating the marine transgression from the east, where the Neotethys Ocean was opening. Permian-Triassic HT-LP metamorphic imprints recorded in the Austroalpine continental units are correlatable to this scenario; these peculiar metamorphic patterns have been widely recognized in lower, intermediate and upper continental crust. HT assemblages mark newly differentiated foliations locally associated with discrete shear zones, mainly in metapelites. Ages inferred for Tmax conditions are comprised between 220 and 295 Ma and Jurassic mineral ages are obtained where LP-LT metamorphic imprints, recorded during uplift and associated with fluid circulation, are dominant. The uplift paths are usually characterized by a high T/P ratio and wide parts of the uplift paths occurred under high thermal regime and the exhumation of some of the deep

  19. Epithermal neutron activation, radiometric, correlation and principal component analysis applied to the distribution of major and trace elements in some igneous and metamorphic rocks from Romania.

    Science.gov (United States)

    Cristache, C I; Duliu, O G; Culicov, O A; Frontasyeva, M V; Ricman, C; Toma, M

    2009-05-01

    Six major (Na, Al, K, Ca, Ti, Fe) and 28 trace (Sc, Cr, V, Mn, Co, Zn, Cu, As, Br, Sr, Rb, Zr, Mo, Sn, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Hf, Ta, W, Th and U) elements were determined by epithermal neutron activation analysis (ENAA) in nine Meridional Carpathian and Macin Mountains samples of igneous and metamorphic rocks. Correlation and principal factor analysis were used to interpret data while natural radionuclides radiometry shows a good correlation with ENAA results. PMID:19231213

  20. Carbonatite diversity in the Central Andes: the Ayopaya alkaline province, Bolivia

    Science.gov (United States)

    Schultz, Frank; Lehmann, Bernd; Tawackoli, Sohrab; Rössling, Reinhard; Belyatsky, Boris; Dulski, Peter

    2004-12-01

    The Ayopaya province in the eastern Andes of Bolivia, 100 km NW of Cochabamba, hosts a Cretaceous alkaline rock series within a Palaeozoic sedimentary sequence. The alkaline rock association comprises nepheline-syenitic/foyaitic to ijolitic intrusions, carbonatite, kimberlite, melilititic, nephelinitic to basanitic dykes and diatremes, and a variety of alkaline dykes. The carbonatites display a wide petrographic and geochemical spectrum. The Cerro Sapo area hosts a small calciocarbonatite intrusion and a multitude of ferrocarbonatitic dykes and lenses in association with a nepheline-syenitic stock. The stock is crosscut by a spectacular REE-Sr-Th-rich sodalite-ankerite-baryte dyke system. The nearby Chiaracke complex represents a magnesiocarbonatite intrusion with no evidence for a relationship to igneous silicate rocks. The magnesiocarbonatite (Σ REE up to 1.3 wt%) shows strong HREE depletion, i.e. unusually high La/Yb ratios (520 1,500). Calciocarbonatites (Σ REE up to 0.5 wt%) have a flatter REE distribution pattern (La/Yb 95 160) and higher Nb and Zr contents. The sodalite-ankerite-baryte dyke system shows geochemical enrichment features, particularly in Na, Ba, Cl, Sr, REE, which are similar to the unusual natrocarbonatitic lavas of the recent volcano of Oldoinyo Lengai, Tanzania. The Cerro Sapo complex may be regarded as an intrusive equivalent of natrocarbonatitic volcanism, and provides an example for carbonatite genesis by late-stage crystal fractionation and liquid immiscibility. The magnesiocarbonatite intrusion of Chiaracke, on the other hand, appears to result from a primary carbonatitic mantle melt. Deep seated mantle magmatism/metasomatism is also expressed by the occurrence of a kimberlite dyke. Neodymium and strontium isotope data (ɛNd 1.4 5.4, 87Sr/86 Sr

  1. Extremadura (Spain): a case to be considered as Global Heritage Stone Province

    Science.gov (United States)

    Mota, Maribel; Tejado, Juanjo; Pereira, Dolores

    2015-04-01

    Extremadura is geologically located in the Iberian Massif, belonging part of the Central Iberian Zone, in the north of the region, and the Ossa Morena zone, in the south of it. The Central Iberian Zone is characterized by the abundance of clastic metasedimentary rocks and greywacke, sandstones, shales, conglomerates, quartzites and lesser amounts of carbonate materials such as limestone and dolomite (600-300 Ma). Also featured are Hercynian granitic intrusions. The rocks from the Ossa-Morena zone are metamorphic, intrusive igneous and volcanic (650-300 Ma). Extremadura, given its strategic geographical position, has been the site of human settlement since ancient times, and this civilisation has left its influence on the building materials used in buildings and monuments. The rocks used in building, are directly related to the geology of the immediate area, since rock outcrops, near the construction are mostly granites, slates and marbles. The historic and artistic heritage from Extremadura includes Roman treasures (like the bridges located in the Via de la Plata, dams, walls and milestones), Islamic and Christian treasures as well as medieval and Renaissance Jewish treasures. Extremadura has three World Heritage Sites declared by UNESCO: the old town of Cáceres, the archaeological site at Merida and the monastery of Guadalupe. The latter is built mainly of bricks and masonry. In Merida, granites and diorites of various facies of the batholiths located north of the city are used together with Sierra Carija's marble and quartzite alluvial gravels from the river Guadiana. Among the constructions in Merida, granite utilisation in the theater and amphitheater, aqueduct of Miracles and the Proserpina dam, are remarkable. The old town of Cáceres is characterised by the presence of narrow streets and monuments, medieval churches and Renaissance palaces, built with granite and flanked by a wall constructed during the Muslim period. This granite comes from the quarries

  2. Titanium and oxygen isotope diffusion in quartz-phenocrysts from a Jurassic rhyolite, Chon Aike Province (Fitz Roy, Patagonia)

    Science.gov (United States)

    Seitz, S.; Putlitz, B.; Baumgartner, L. P.; Escrig, S.; Meibom, A.; Leresche, S.; Vennemann, T. W.

    2014-12-01

    The volcanic El Quemado Complex was deposited during the breakup of Gondwana during the Middle and Late Jurassic. It is part of a large silicic igneous province, which includes the Chon Aike Province in Southern Patagonia and related rocks from the Antarctic Peninsula [1]. The Complex consists of rhyolitic and dacitic ignimbrites and air-fall tuffs, intercalated with andesitic to rhyolitic lava flows. New LA-ICPMS U/Pb-dates of zircons from the Fitz Roy area yield ages between 148 and 153Ma. No inherited zircons were found, suggesting that the temperature of 850°C calculated from zircon saturation is a minimum temperature. Lava flows are typically rich in quartz phenocrysts, which preserved magmatic trace element zoning, as revealed by cathodoluminescence (CL): light cores are surrounded by several darker and lighter zones towards the rim. The δ18O-values for quartz of between 11 to 14 ‰ are compatible with a crustal source for the magma and the SIMS analyses of phenocrysts reveal no zoning in O-isotope compositions. High-resolution Ti-profiles were obtained by NanoSIMS with a beam size of ~200 nm and a minimum step size of ~120 nm. Several lines perpendicular to the magmatic zoning of the quartz-phenocrysts were measured. The profiles show sharp changes in the 48Ti/29Si-ratio over a distance of 5 μm, which correlate with CL-intensity changes. The profiles can be used for diffusion chronometry. The distances obtained from NanoSIMS profiles were used to calculate maximum diffusional relaxation times. Assuming a step function as initial condition and extrusion temperatures from zircon saturation of 850°C, we obtain a maximum residence time for the quartz-phenocrysts of 3.5 years. [1] Pankhurst R.J., Riley T.R., Fanning C.M., Kelley S.P., 2000. J. Pet., 41, 605-625.

  3. The role of carbon from recycled sediments in the origin of ultrapotassic igneous rocks in the Central Mediterranean

    Science.gov (United States)

    Conticelli, Sandro; Avanzinelli, Riccardo; Ammannati, Edoardo; Casalini, Martina

    2015-09-01

    The Central Mediterranean region is one of the most important areas on Earth for studying subduction-related potassic and ultrapotassic magmatism, derived from partial melting of the metasomatised lithospheric mantle wedge. In this region, leucite-free (i.e., lamproite) and leucite-bearing (i.e., kamafugite, leucitite, and plagioleucitite) ultrapotassic rocks closely occur, in a time-related progression, linked to the evolution of both the mantle source and the regional tectonic regime. Time- and space-related magmatism migration followed the roll-back of the subducting slab and the anticlockwise drift of the Italian Peninsula. Leucite-free silica-rich lamproites are restricted to the early stage of magmatism and are associated with ultrapotassic shoshonites and high-K calc-alkaline volcanic rocks. Leucite-bearing (i.e., Roman Province) rocks are erupted consistently later than lamproite-like and associated shoshonitic rocks, with post-leucititic volcanism occurring in the late stage of volcanic activity with eruption of alkali-basaltic to latitic and trachytic rocks, often after major caldera-forming events. Present-day ultrapotassic volcanism is restricted to the Neapolitan area. Central Mediterranean potassic and ultrapotassic rocks are extremely enriched in incompatible trace elements with variable fractionation of Ta, Nb, and Ti in comparison to Th and large ion lithophile elements (LILE). They are also variably enriched in radiogenic Sr and Pb and unradiogenic Nd. The main geochemical and isotopic signatures are consistent with sediment recycling within the mantle wedge via subduction. A twofold metasomatism, induced by the recycle of pelitic sediments and dehydration of lawsonite-bearing schists generates the early metasomatic events that enriched the mantle wedge from which leucite-free ultrapotassic rocks (i.e., lamproite) were generated. Recycling of carbonate-rich pelites played an important role in the shift to silica-undersaturated ultrapotassic rocks

  4. The Agricultural Export Competitiveness and Independent Innovation in Liaoning Province

    Institute of Scientific and Technical Information of China (English)

    Guimin; WANG; Haixian; XIA

    2013-01-01

    Through the vertical and horizontal analysis of agricultural export data in Liaoning Province during the period 2006-2010,we can find that Liaoning Province has already a major exporter of agricultural products,but there is no significant increase in many indicators with great fluctuation or declining trend. Meanwhile,compared with other provinces,the competitive advantages of agricultural export in Liaoning Province are not obvious,lacking competitive potential. Analysis shows that it is a strenuous task for Liaoning Province to transform from a major exporter of agricultural products to strong export province; during the course,relying on independent innovation is the fundamental guarantee. Liaoning Province should rely on independent innovation,to create new agricultural varieties,lead the international standards of agricultural products,form the brand agriculture,and improve the agricultural industry chain.

  5. Coherent water transport across the South Atlantic

    CERN Document Server

    Wang, Y; Beron-Vera, F J

    2015-01-01

    The role of mesoscale eddies in transporting Agulhas leakage is investigated using a recent technique from nonlinear dynamical systems theory applied on geostrophic currents inferred from the over two-decade-long satellite altimetry record. Eddies are found to acquire material coherence away from the Agulhas retroflection, near the Walvis Ridge in the South Atlantic. Yearly, 1 to 4 coherent material eddies are detected with diameters ranging from 40 to 280 km. A total of 23 eddy cores of about 50 km in diameter and with at least 30% of their contents traceable into the Indian Ocean were found to travel across the subtropical gyre with minor filamentation. No more than 5\\% of such cores pour their contents on the North Brazil Current. While ability of eddies to carry Agulhas leakage northwestward across the South Atlantic is supported by our analysis, this is more restricted than suggested by earlier ring transport assessments.

  6. Displaced fracture through the anterior atlantal synchondrosis

    Energy Technology Data Exchange (ETDEWEB)

    Thakar, Chrishan; Allibone, James [Royal National Orthopaedic Hospital NHS Trust, Department of Spinal Deformity, Stanmore, Middlesex (United Kingdom); Harish, Srinivasan [Royal National Orthopaedic Hospital NHS Trust, Department of Radiology, Stanmore, Middlesex (United Kingdom); Saifuddin, Asif [Royal National Orthopaedic Hospital NHS Trust, Department of Radiology, Stanmore, Middlesex (United Kingdom); University College, The Institute of Orthopaedics and Musculoskeletal Sciences, London (United Kingdom)

    2005-09-01

    In the acute setting, accurate radiological interpretation of paediatric cervical spine trauma can be difficult due to a combination of normal variants and presence of multiple synchondroses. We present a rare case of a fracture through the anterior atlantal synchondrosis in a paediatric spine. A five-year-old boy, who fell backwards onto the top of his head while swinging across on a monkey bar frame, presented with neck pain, cervical muscle spasm and decreased right lateral rotation and extension of his neck. Computed tomography showed a displaced diastatic fracture through right anterior atlantal synchondrosis. There are only 12 cases of paediatric C1 fractures reported in the world literature. The importance of considering this diagnosis in the appropriate clinical setting, and the normal variants in the paediatric atlas that can cause diagnostic dilemma to the interpreting radiologist, are discussed in this case report. (orig.)

  7. Storms of Mediterranean and Atlantic legends

    Science.gov (United States)

    Schoenenwald, N.; Tabeaud, M.

    2009-09-01

    Weather extremes and notably wind storms are very often the channel ones since they are suspected of being the outward signs of climate change. However, even if audiovisual medias talk about wind storms in a very similar way, tales and legends stories account for the richness of their representations. Coastal and insular regions, whatever Atlantic or Mediterranean, are the ones where wind storms are most mentioned. The comparison between the tales and legends of these two regions, with distinct climatic characteristics, allows to underline the similarities and dissimilarities about the impregnation (or impact) of wind storms on these territories. Winds and storms distinguish spaces through vocabulary which can be peculiar to a region. Nevertheless, they also bring them together because above the local cultures is the human thought upon which wind storms create comparable perceptions, whatever the region. Key words: wind storms, Mediterranean regions, Atlantic regions, perceptions, representations.

  8. Modes of winter precipitation variability in the North Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Zorita, E. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik; Saenz, J.; Fernandez, J.; Zubillaga, J. [Bilbao Univ. (Spain)

    2001-07-01

    The modes of variability of winter precipitation in the North Atlantic sector are identified by Empirical Orthogonal Functions Analysis in the NCEP/NCAR global reanalysis data sets. These modes are also present in a gridded precipitation data set over the Western Europe. The large-scale fields of atmospheric seasonal mean circulation, baroclinic activity, evaporation and humidity transport that are connected to the rainfall modes have been also analyzed in order to investigate the physical mechanisms that are causally linked to the rainfall modes. The results indicate that the leading rainfall mode is associated to the North Atlantic oscillation and represents a meridional redistribution of precipitation in the North Atlantic through displacements of the storm tracks. The second mode is related to evaporation anomalies in the Eastern Atlantic that precipitate almost entirely in the Western Atlantic. The third mode seems to be associated to meridional transport of water vapor from the Tropical Atlantic. (orig.)

  9. North Atlantic, ITCZ, and Monsoonal Climate Links

    Science.gov (United States)

    Haug, G. H.; Deplazes, G.; Peterson, L. C.; Brauer, A.; Mingram, J.; Dulski, P.; Sigman, D. M.

    2008-12-01

    Major element chemistry and color data from sediment cores in the anoxic Cariaco Basin off Venezuela record with (sub)annual resolution large and abrupt shifts in the hydrologic cycle of the tropical Atlantic during the last 80 ka. These data suggest a direct connection between the position of the ITCZ over northern South America, the strength of trade winds, and the temperature gradient to the high northern latitudes, ENSO, and monsoonal climate in Asia. The mechanisms behind these decadal-scale ITCZ-monsoon swings can be further explored at major climate transitions such as the onset of Younger Dryas cooling at ~12.7 ka, one of the most abrupt climate changes observed in ice core, lake and marine records in the North Atlantic realm and much of the Northern Hemisphere. Annually laminated sediments from ideally record the dynamics of abrupt climate changes since seasonal deposition immediately responds to climate and varve counts accurately estimate the time of change. We compare sub-annual geochemical data from a lake in Western Germany, which provides one of the best-dated records currently available for this climate transition, with the new the Cariaco Basin record and a new and higher resolution record from Lake Huguang Maar in China, and the Greenland ice core record. The Lake Meerfelder Maar record indicates an abrupt increase in storminess, occurring from one year to the next at 12,678 ka BP, coincident with other observed climate changes in the region. We interpret this shift of the wintertime winds to signify an abrupt change in the North Atlantic westerlies to a stronger and more zonal jet. The observed wind shift provides the atmospheric mechanism for the strong temporal link between North Atlantic overturning and European climate during the last deglaciation, tightly coupled to ITCZ migrations observed in the Cariaco Basin sediments, and a stronger east Asian Monsoon winter monsoon as seen in lake Huguang Maar, when cave stalagmite oxygen isotope data

  10. Fisheries. Population of origin of Atlantic cod.

    Science.gov (United States)

    Nielsen, E E; Hansen, M M; Schmidt, C; Meldrup, D; Grønkjaer, P

    2001-09-20

    Most of the world's cod (Gadus morhua) fisheries are now tightly regulated or closed altogether. Being able to link individual fish to their population of origin would assist enormously in policing regulations and in identifying poachers. Here we show that microsatellite genetic markers can be used to assign individual cod from three different populations in the northeastern Atlantic Ocean to their population of origin. PMID:11565021

  11. Indian - Atlantic interocean exchange: variability and controls

    OpenAIRE

    Schouten, Mathijs Wilhelmus

    2003-01-01

    South of Africa, warm Indian Ocean water enters the Atlantic Ocean by means of large Agulhas Rings. These rings, with diameters up to 350 km and reaching all the way to the ocean floor at 5 km depth, form an important link in the global thermohaline circulation, which is the driving force behind the moderate temperatures over Northern Europe. For six years, the shedding of Agulhas rings has been monitored from space, using satellite altimeter measurements of the sea surface height. Rings can ...

  12. The Leiodidae (Coleoptera of Atlantic Canada: new records, faunal composition, and zoogeography

    Directory of Open Access Journals (Sweden)

    Christopher Majka

    2008-09-01

    Full Text Available The Leiodidae (the round fungus beetles, the small carrion beetles, and the mammal nest beetles of Atlantic Canada (New Brunswick, Newfoundland and Labrador, Nova Scotia, and Prince Edward Island are surveyed. Twenty five species, including Colon (Colon politum Peck and Stephan, Colon (Myloechus forceps Hatch, Colon (Myloechus incisum Peck and Stephan, Colon (Myloechus schwarzi Hatch, Hydnobius arizonensis Horn, Anogdus dissimilis Blatchley, Anogdus potens (Brown, Cyrtusa subtestacea (Gyllenhal, Leiodes puncticollis (Thompson, Leiodes rufipes (Gebler, Agathidium atronitens Fall, Agathidium depressum Fall, Agathidium difforme (LeConte, Agathidium mollinum Fall, Agathidium oniscoides Palisot de Beauvois, Agathidium pulchrum LeConte, Agathidium repentinum Horn, Agathidium rusticum Fall, Gelae parile (Fall, Anisotoma blanchardi (Horn, Anisotoma discolor (Melsheimer, Anisotoma geminata (Horn, Anisotoma globososa Hatch, and Prionochaeta opaca (Say are newly recorded in Atlantic Canada. One of these, Hydnobius arizonensis, is newly recorded in Canada. Colon (Myloechus hubbardi Horn is newly recorded in the Maritime Provinces. Eight species are newly recorded in New Brunswick, 29 in Nova Scotia, two on Prince Edward Island, 12 on insular Newfoundland, and five in Labrador for a total of 56 new jurisdictional records. Catops paramericanus Peck and Cook and Catops simplex Say are newly recorded from mainland Nova Scotia, and records are provided to verify the occurrence of Leiodes impersonata Brown and Leiodes punctostriata Kirby in Nova Scotia, and Leptinillus validus (Horn in insular Newfoundland. Three species, Agathidium hatchi Wheeler, Catops americanus Hatch, and Sciodrepoides watsoni (Spence, are removed from the faunal list of New Brunswick. As a result, 66 species of Leiodidae have now been recorded from Atlantic Canada. The name Anisotoma obsoleta (Horn is revalidated while the name Anisotoma horni Wheeler is newly designated a synonym of A

  13. Atlantic and indian oceans pollution in africa

    Science.gov (United States)

    Abubakar, Babagana

    Africa is the second largest and most populated continent after Asia. Geographically it is located between the Atlantic and Indian Oceans. Most of the Africa's most populated and industrialized cities are located along the coast of the continent facing the Atlantic and Indian Oceans, example of such cities include Casablanca, Dakar, Accra, Lagos, Luanda and Cape town all facing the Atlantic Ocean and cities like East London, Durban, Maputo, Dar-es-salaam and Mogadishu are all facing the Indian Ocean. As a result of the geographical locations of African Coastal Cities plus increase in their population, industries, sea port operations, petroleum exploration activities, trafficking of toxic wastes and improper waste management culture lead to the incessant increase in the pollution of the two oceans. NATURE OF POLLUTION OF THE ATLANTIC OCEAN i. The petroleum exploration activities going on along the coast of "Gulf of Guinea" region and Angola continuously causes oil spillages in the process of drilling, bunkering and discharging of petroleum products in the Atlantic Ocean. ii. The incessant degreasing of the Sea Ports "Quay Aprons" along the Coastal cities of Lagos, Luanda, Cape Town etc are continuously polluting the Atlantic Ocean with chemicals. iii. Local wastes generated from the houses located in the coastal cities are always finding their ways into the Atlantic Ocean. NATURE OF POLLUTION OF THE INDIAN OCEAN i. Unlike the Atlantic ocean where petroleum is the major pollutant, the Indian Ocean is polluted by Toxic / Radioactive waste suspected to have been coming from the developed nations as reported by the United Nations Environmental Programme after the Tsunami disaster in December 2004 especially along the coast of Somalia. ii. The degreasing of the Quay Aprons at Port Elizabeth, Maputo, Dar-es-Salaam and Mongolism Sea Ports are also another major source polluting the Indian Ocean. PROBLEMS GENERATED AS A RESULT OF THE OCEANS POLLUTION i. Recent report

  14. In Brief: Atlantic seasonal hurricane forecast

    Science.gov (United States)

    Showstack, Randy

    2007-12-01

    Two hurricane forecasters are predicting that 2008 will be an above-average Atlantic basin tropical cyclone season with an above-average probability of a major hurricane making landfall in the United States. During 2008, there could be about seven hurricanes (the annual average is 5.9) and 13 named storms (the average is 9.6), according to a 7 December report by Philip Klotzbach, research scientist at Colorado State University in Fort Collins, and William Gray, university professor emeritus of atmospheric sciences. The forecasters indicate that they believe the Atlantic basin is in an active hurricane cycle that is associated with a strong thermohaline circulation and an active phase of the Atlantic Multidecadal Oscillation. The report notes that, ``real-time operational early December forecasts have not shown forecast skill over climatology during this 16-year period [1992-2007]. This has occurred despite the fact that the skill over the hindcast period...showed appreciable skill.'' For more information, visit the Web site: http://hurricane.atmos.colostate.edu/Forecasts/2007/dec2007/dec2007.pdf.

  15. Local and remote impacts of a tropical Atlantic salinity anomaly

    OpenAIRE

    Mignot, Juliette; Frankignoul, Claude

    2009-01-01

    The climatic impacts of an enhanced evaporation prescribed during 50 years in the tropical Atlantic are investigated in a coupled ocean-atmosphere general circulation model. Locally, the salinity increase leads to a rapid deepening and cooling of the surface mixed layer. This induces a deepening of the equatorial undercurrent and an intensification of the south equatorial current. A remote atmospheric response to the tropical Atlantic perturbation is detected in the North Atlantic sector afte...

  16. Mechanisms and predictability of North Atlantic - European Climate

    OpenAIRE

    Pohlmann, H.

    2005-01-01

    This study investigates the mechanisms of North Atlantic-European climate using atmosphere general circulation models (AGCMs). Experiments with the AGCM ECHAM4, in which the sea surface temperature (SST) forcing is restricted to either the Atlantic or the Indo-Pacific oceans, show that both oceanic regions have an influence on North Atlantic-European climate in winter. In the experiment with SST forcing restricted to the Indo-Pacific oceans the atmospheric response projects on the North Atlan...

  17. Evidence of remote forcing in the Equatorial Atlantic ocean

    OpenAIRE

    Servain, J.; Picaut, Joël; Merle, Jacques

    1982-01-01

    An analysis of sea-surface temperature (STT) and surface winds in selected areas of the Tropical Atlantic indicates that the nonseasonal variability of SST in the Eastern Equatorial Atlantic (Gulf of Guinea) is highly correlated with the nonseasonal variability of the zonal wind stress in the Western Equatorial Atlantic. A negative (positive) anomaly of the zonal wind stress near the North Brazilian coast is followed by a positive (negative) SST anomaly in the Gulf of Guinea about one month l...

  18. 75 FR 33242 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; Weakfish Fishery

    Science.gov (United States)

    2010-06-11

    ... the provisions of the Atlantic Coastal Fisheries Cooperative Management Act (Atlantic Coastal Act... National Oceanic and Atmospheric Administration RIN 0648-XW45 Atlantic Coastal Fisheries Cooperative Management Act Provisions; Weakfish Fishery AGENCY: National Marine Fisheries Service (NMFS),...

  19. NEFSC 2012 Atlantic Herring Acoustic/Midwater Trawl Survey (PC1206, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  20. NEFSC 2004 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0413, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  1. NEFSC 2006 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0615, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  2. NEFSC 2005 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0512, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  3. NEFSC 2010 Atlantic Herring Acoustic/Midwater Trawl Survey (DE1010, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  4. NEFSC 2011 Atlantic Herring Acoustic/Midwater Trawl Survey (DE1108, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  5. NEFSC 1998 Atlantic Herring Acoustic/Midwater Trawl Survey (DE9810, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  6. NEFSC 2002 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0208, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  7. NEFSC 2009 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0910, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  8. A Glance at Bohai Bay Oil Province

    Institute of Scientific and Technical Information of China (English)

    Gao Shoubai

    1995-01-01

    @@ Chinese oil industry keeps on developing in 1994. The oil production of Bohai Bay Oil Province located in East China also keeps on growing. Geologically,the total area of Bohai Bay Basin is about 200 000 km2 and the main structural units are: Liaohe Depression, Huanghua Depression,Jizhong Depression, Linqing Depression, Jiyang Depression, Changwei Depression, Bozhong Depression,Chengning Uplift and Cangjing Uplift (see figure 1). Area of the main structural units is listed in following:

  9. Nitrate Concentration in Groundwater in Isfahan Province

    OpenAIRE

    S.F Mousavi; M. Afyuni; A. Jafari Malekabadi; Khosravi, A.

    2004-01-01

    In recent decades, the use of nitrogen fertilizers has increased irrespective of their effects on soil properties, agricultural products and, particularly, on environmental pollution. Nitrate easily leaches from soils into groundwater. The objective of this study was to determine temporal and spatial nitrate concentrations in groundwater in agricultural, industrial and urban regions in some parts of Isfahan Province. Water samples were collected monthly from 75 agricultural, industrial, and u...

  10. Wind energy in the province Friesland, Netherlands

    International Nuclear Information System (INIS)

    In spite of the fact that wind energy is competitive, both technically as economically, it appears to be more and more difficult to install new wind turbine capacity in the Dutch province Friesland. The most important constraints are the limited capacity of the grid, licensing, noise pollution, and landscaping. It is expected that those constraints and objections from people living in the neighbourhood of wind turbines will get bigger

  11. An ethnobotanical survey on hormozgan province, Iran

    Directory of Open Access Journals (Sweden)

    Omid Safa

    2012-12-01

    Conclusion: This study revealed that the people of Hormozgan province have a rich knowledge of natural resources. The use and consumption of medicinal plants are still important parts of their life.Rational use of native medicinal plants may benefit and improve their living standards and quality of life. The results of this study can be used as a basis for selecting herbs for further pharmacological, phytochemical, and pharmacognostical studies.

  12. Myxomycetes from Trabzon and Giresun Provinces (Turkey)

    OpenAIRE

    Ocak, İjlal; İsmet HASENEKOĞLU

    2005-01-01

    This study serves as a checklist of the myxomycetes of Trabzon and Giresun provinces, Turkey. Sixty-one myxomycete were identified, 20 of which were collected in the field and 41 grown in moist chamber culture. In addition, we report all taxa new for Giresun and Trabzon, including the following 15 taxa new to Turkey: Licea biforis Morgan, Cribraria intricata Schrad., C. macrocarpa Schrad., Lycogala exiguum Morgan, Arcyria globosa Schw., A. nigella Emoto, A. magna Rex, Trichia erecta Rex, Dian...

  13. Ornithological observations on Karadag, Konya province, Turkey

    OpenAIRE

    KIRWAN, Guy M.

    1998-01-01

    Few ornithological observations are available from the isolated massifs of the Central Plateau; and for Karadag, Konya province there exists only the records of Ramsay (1914) in the summer of 1907. Observations from a visit in June 1996 are pre-sented and compared with those of Ramsay and data from other sources, principally Roselaar (1995). The total number of bird species recorded on the mountain is 53, of which 18 have been proven to breed; it seems probable that the globally threatened...

  14. Grassroots Participatory Budgeting Process in Negros Province

    OpenAIRE

    del Prado, Fatima; Rosellon, Maureen Ane D.; Florendo, Gabriel Antonio

    2015-01-01

    This paper is a narrative account and assessment of the grassroots participatory budgeting (GPB) process in three municipalities of the Negros Province, namely, Sagay City, Hinigaran, and Cauayan. The GPB process was implemented with the objective of empowering civil society organizations (CSOs) to engage with local government and national government agencies in local development planning. This study is a rapid assessment of the GPB process and involved interviews and focus group discussions ...

  15. CARINA oxygen data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    I. Stendardo

    2009-12-01

    Full Text Available In the CARINA (Carbon dioxide in the Atlantic Ocean project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the comparison of deep ocean data at places that were sampled by different cruises at different times. Initial adjustments to the individual cruises were then determined by an inverse procedure that computes a set of adjustments that requires the minimum amount of adjustment and at the same time reduces the offsets in an optimal manner. The initial adjustments were then reviewed by the CARINA members, and only those that passed the following two criteria were adopted: (i the region is not subject to substantial temporal variability, and (ii the adjustment must be based on at least three stations from each cruise. No adjustment was recommended for cruises that did not fit these criteria. The final CARINA-Oxygen dataset has 103414 oxygen samples from 9491 stations obtained during 98 cruises covering three decades. The sampling density of the oxygen data is particularly good in the North Atlantic north of about 40° N especially after 1987. In contrast, the sample density in the South Atlantic is much lower. Some cruises appear to have poor data quality, and were subsequently omitted from the adjusted dataset. Of the data included in the adjusted dataset, 20% were adjusted with a mean adjustment of 2%. Due to the achieved internal consistency, the resulting product is well suited to produce an improved climatology or to study long-term changes in the oxygen content of the ocean. However, the adjusted dataset is not necessarily better suited than the unadjusted data to

  16. Simulated water productivity in Gansu Province, China

    Science.gov (United States)

    Zhan, Jinyan; Sun, Zhongxiao; Wang, Zhan; Chen, Jiancheng; Li, Zhaohua

    Economic value of water and economic analysis of water use management in Gansu Province of China have attracted widespread public attention. With the socioeconomic development, research on water resources has become more important than before. In this study, we define "water productivity" as the changes of economic production outputs of sectoral activities in every cubic meter of water input, which is also the technical coefficient of water resource use in each sector. According to Computable General Equilibrium (CGE) framework, based on the Input-Output Table 2007 and water resources bulletin of Gansu Province, we introduced the water into the ORANI-G (A Generic Single-Country Computable General Equilibrium model) model through the nested constant elasticity of substitution (CES) production function to analyze the changes of economic productions caused by water supply changes. We then examined water productivity in different sectors. Empirical results showed that current water productivity is underestimated. Agricultural water productivity is lower than that of the secondary and tertiary industries, even although agricultural water use is the largest part of water use in Gansu Province, and therefore improving agricultural water productivity can greatly mitigate the water shortage. Simulation results indicate that industrial transformation and development of water-saving industries will also mitigate water scarcity. Moreover, sensitivity analysis shows that the empirical results are robust under different scenarios. The results also show that higher constant elasticity of substitution rate (CES) between water and other production factors will contribute to sustainable development.

  17. Igneous and Sedimentary Compositions from Four Landing Sites on Mars from the Alpha Particle X-Ray Spectrometer (APXS)

    Science.gov (United States)

    Gellert, R.; Arvidson, R. E.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. W.; Morris, R. W.; Squyres, S. W.; VanBommel, S.; Yen, A. S.

    2016-01-01

    The APXS - supported and promoted strongly by Heinrich Waenke - on all four Mars Rovers has returned compositional data from about 1000 rocks and soil targets along the combined traverses of over 60 kilometers. Providing precise and accurate bulk chemistry with typically 16 quantified elements, the APXS is a powerful and versatile tool that when combined with the ability to traverse to key rocks and soils has provided critical information needed to understand the geologic evolution of Mars. APXS data allow comparisons among landing sites, provide ground truth for orbiters and connections back to SNC meteorites. The soils and dust are basaltic in character and represent the average Mars composition similar to Adirondack basalts from Gusev crater but with unambiguous elevated and correlated S, Cl and Zn contents. At all four landing sites the APXS found several rocks with a felsic composition. The similarity is best assessed in a logarithmic ratio plot of rock normalized to the average soil composition (Fig.1). High alkaline, Al, and low Mg, Fe, low S, Cl and Ni, Zn as well as an Fe/Mn ratio of approximately 50 indicate a likely unaltered and igneous origin. Sediments, e.g. the Burns formation, with approximately 25 wt% SO3 at Meridiani Planum have been documented over 10s of kilometers (Fig. 2). This formation is compositionally homogeneous, but showing the removal of MgSO4 and a threefold increase in Cl downhill in 2 craters. The degraded rim of the Noachian crater Endeavour resembles average Mars crust, with local Ca, Mg and Fe sulfate alteration and elevated Mn, some felsic rocks, and high Al, Si and low Fe rocks, possibly indicating clays. Unusual soils at Gusev crater in the area surrounding Home Plate include some very rich in ferric sulfate salts (up to 35 wt% SO3) and some with 90% wt% SiO2, possibly indicating fumerolic activities. Rocks in the Columbia Hills show significant signs of alteration including elevated S, Cl and Br in the abraded interior. At

  18. Division and characteristics of tectonic units of intrusive rocks in Henan province%河南省侵入岩构造单元的划分及其特征

    Institute of Scientific and Technical Information of China (English)

    彭松民; 李振国; 王令全; 李文智; 付治国

    2014-01-01

    河南省岩浆活动显示多期活动的特征,侵入岩较发育,占全省基岩出露面积的23.5%以上,岩石类型齐全,与其有成生联系的矿产资源丰富。文章参考潜力评价全国构造侵入岩带的总体划分方案,结合河南省岩浆岩分布特征、岩石类型、岩石组合及岩浆岩的演化规律,划分出2个构造侵入岩省、5个构造侵入岩带、12个构造侵入岩亚带、进一步划分出22个构造侵入岩段,并对其基本特征及与成矿关系进行总结。%In Henan province,the magmatic activity shows its feature of multi-stage,while the intrusive rocks are widely distributed and accounts for more than 23.5% of the total bedrock outcrop area.The multiple rock types result in abundant genetic correlative mineral resources.Based on the division of national tectonic intrusive zone,and according to the distribution of igneous rocks,rock types,rock assemblages and evolu-tion of igneous rocks in Henan,the author creates 2 tectonic intrusive rock provinces,5 structure intrusive rock belts,12 structure intrusive rock sub-belts,and 22 tectonic intrusive rock segments.The basic charac-teristics and mineralization relationship are concluded in this paper.

  19. The North Atlantic Oscillation: variability and interactions with the North Atlantic ocean and Artic sea ice

    Energy Technology Data Exchange (ETDEWEB)

    Jung, T.

    2000-07-01

    The North Atlantic oscillation (NAO) represents the dominant mode of atmospheric variability in the North Atlantic region and describes the strengthening and weakening of the midlatitude westerlies. In this study, variability of the NAO during wintertime and its relationship to the North Atlantic ocean and Arctic sea ice is investigated. For this purpose, observational data are analyzed along with integrations of models for the Atlantic ocean, Arctic sea ice, and the coupled global climate system. From a statistical point of view, the observed NAO index shows unusually high variance on interdecadal time scales during the 20th century. Variability on other time scales is consistent with realizations of random processes (''white noise''). Recurrence of wintertime NAO anomalies from winter-to-winter with missing signals during the inbetween nonwinter seasons is primarily associated with interdecadal variability of the NAO. This recurrence indicates that low-frequency changes of the NAO during the 20th century were in part externally forced. (orig.)

  20. 78 FR 24148 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2013-04-24

    ..., 2011 (76 FR 62331), we published an NOI that announced the stock status determinations for various... Magnuson-Stevens Act. On November 26, 2012, we published a proposed rule (77 FR 70552) for draft Amendment... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS),...

  1. 75 FR 57235 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2010-09-20

    ... amendment is Amendment 3 to the 2006 Consolidated HMS FMP (75 FR 30484, June 1, 2010), which was based on... FR 250, January 5, 2010). Depending on the outcome of this ANPR process, NMFS will consider rules or... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS),...

  2. 76 FR 65673 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures; Correction

    Science.gov (United States)

    2011-10-24

    ... Register notice on October 7, 2011 (76 FR 62331). The notice also announced NMFS' intent to undertake... contains an error and is in need of correction. Correction Accordingly, in the October 7, 2011 (76 FR 62331... Species; Atlantic Shark Management Measures; Correction AGENCY: National Marine Fisheries Service...

  3. 76 FR 62331 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2011-10-07

    ..., dusky, and blacknose sharks in the U.S. Atlantic and Gulf of Mexico were recently completed (76 FR 61092... (August 29, 2011, 76 FR 53652). Commercial regulations for blacknose sharks include, but are not limited... (May 4, 2010, 75 FR 23676). The Assessment Process was conducted via a series of webinars, during...

  4. 77 FR 31562 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2012-05-29

    ... October 7, 2011(76 FR 62331). This amendment is designed to rebuild and/or end overfishing on several... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS), National... considering the inclusion of Gulf of Mexico blacktip sharks in an amendment to the 2006 Consolidated...

  5. 78 FR 4129 - Fisheries of the South Atlantic; South Atlantic Fishery Management Council; Public Meetings

    Science.gov (United States)

    2013-01-18

    .... Receive an update on the Atlantic States Marine Fisheries Communication Group Social Media Workshop. 3... management responsibility for Nassau grouper in the Gulf of Mexico, increases the number of crew members... SAFMC Visioning Process for snapper grouper species. 6. Discuss strategic planning. Law Enforcement...

  6. 78 FR 54195 - Atlantic Highly Migratory Species; Atlantic Commercial Shark Fisheries

    Science.gov (United States)

    2013-09-03

    ... implemented and analyzed in the 2013 shark quota final rule (77 FR 75896, December 26, 2013) and in the final... Species; Atlantic Commercial Shark Fisheries AGENCY: National Marine Fisheries Service (NMFS), National.... SUMMARY: NMFS is transferring 68 metric tons (mt) dressed weight (dw) of non-blacknose small coastal...

  7. 76 FR 62042 - Fisheries of the South Atlantic; South Atlantic Fishery Management Council; Public Meeting

    Science.gov (United States)

    2011-10-06

    ... Conservation Division; the Council's Invasive Species Policy and the Coral Reef Conservation Program Grant Projects; and the U.S. Coral Reef Task Force Meeting. Special Accommodations These meetings are physically.... SUMMARY: The South Atlantic Fishery Management Council (Council) will hold a meeting of its Coral...

  8. Archaean associations of volcanics, granulites and eclogites of the Belomorian province, Fennoscandian Shield and its geodynamic interpretation

    Science.gov (United States)

    Slabunov, Alexander

    2013-04-01

    An assembly of igneous (TTG-granitoids and S-type leucogranites and calc-alkaline-, tholeiite-, kometiite-, boninite- and adakite-series metavolcanics) and metamorphic (eclogite-, moderate-pressure (MP) granulite- and MP amphibolite-facies rocks) complexes, strikingly complete for Archaean structures, is preserved in the Belomorian province of the Fennoscandian Shield. At least four Meso-Neoarchaean different-aged (2.88-2.82; 2.81-2.78; ca. 2.75 and 2.735-2.72 Ga) calc-alkaline and adakitic subduction-type volcanics were identified as part of greenstone belts in the Belomorian province (Slabunov, 2008). 2.88-2.82 and ca. 2.78 Ga fore-arc type graywacke units were identified in this province too (Bibikova et al., 2001; Mil'kevich et al., 2007). Ca.2.7 Ga volcanics were generated in extension structures which arose upon the collapse of an orogen. The occurrence of basalt-komatiite complexes, formed in most greenstone belts in oceanic plateau settings under the influence of mantle plumes, shows the abundance of these rocks in subducting oceanic slabs. Multiple (2.82-2.79; 2.78-2.76; 2.73-2.72; 2.69-2.64 Ga) granulite-facies moderate-pressure metamorphic events were identified in the Belomorian province (Volodichev, 1990; Slabunov et al., 2006). The earliest (2.82-2.79 Ga) event is presumably associated with accretionary processes upon the formation of an old continental crust block. Two other events (2.78-2.76; 2.73-2.72 Ga) are understood as metamorphic processes in suprasubduction setting. Late locally active metamorphism is attributed to the emplacement of mafic intrusions upon orogen collapse. Three groups of crustal eclogites with different age were identified in the Belomorian province: Mesoarchaean (2.88-2.86 and 2.82-2.80 Ga) eclogites formed from MORB and oceanic plateau type basalts and oceanic high-Mg rocks (Mints et al., 2011; Shchipansky at al., 2012); Neoarchaean (2.72 Ga) eclogites formed from MORB and oceanic plateau type basalts. The formation of

  9. Geophysical evidence of a Large Igneous Province (LIP) in the West Antarctic Rift System (WARS), and its potential influence on the stability of the West Antarctic Ice Sheet (WAIS)

    Science.gov (United States)

    Behrendt, J. C.

    2010-12-01

    The WAIS flows through the volcanically active WARS. The inland rift shoulder ranges from 4-5 km elevation, (5-7 km relief, the greatest in the world); it is coincident with the Transantarctic Mountains from northern Victoria land bordering the Ross Sea, south along the west and south side of the Ross Ice Shelf to the Horlick Mountains. It forms the boundary between East and West Antarctica in this area, but diverges to the Ellsworth Mountains and forms the inland boundary of the WAIS and WARS there. Throughout the WARS shoulder to the Horlick Mountains, exposures of mostly late Cenozoic alkaline volcanic rocks are reported, as is the case in the coastal Marie Byrd Land area on the Southern Ocean aide of the WARS. The Transantarctic Mountains, continue at a much lower elevation (2000-750 m) to form the boundary between East and West Antarctica in the Filchner Ice Shelf area. Aeromagnetic and radar ice-sounding surveys over the WAIS indicated numerous high-amplitude (100->1000 nT),5-50-km width, shallow-source, magnetic anomalies over a very extensive area (>500,000 km2 ) that has been interpreted as evidence of mostly subglacial volcanic eruptions (“volcanic centers”). Behrendt et al, (2005, 2008) interpreted these anomalies as >1000 "volcanic centers" requiring high remanent normal (and at least 10% reversed) magnetizations in the present field direction. These data were interpreted to show that >80% of the anomaly sources at the bed of the WAIS, were modified by the moving ice, requiring a younger age than the WAIS (~25 Ma). Several active volcanoes have shown evidence of eruption through the WAIS and several other active volcanoes are present beneath the WAIS. Although exposed volcanoes surrounding the WAIS extend in age to ~34 Ma., Mt Erebus (Takahe (1000 volcanic, magnetic-anomaly sources are active today, subglacial volcanism may still have a significant effect on the dynamics of the WAIS. Active subglacial volcanism was interpreted from aerogeophysical data reported by Blankenship et al., (1993, Mt. Casertz), and Corr and Vaughan, (2008, near Hudson Mts.), who raised the question of possible volcanic effects on the regime of the WAIS. Wingham et al. (2009) reported a mean volume loss from 2.6 to 10.1 km3/yr from 1995 to 2006 for the Pine Island Glacier in the vicinity of the active subglacial volcano near the Hudson Mts. Probably wet-based areas of the WAIS would be the most likely to be impacted. I discuss these geophysical data and conclude, future effects on the stability of the WAIS should not be ignored, as the rapid changes observed in the past 20 years resulting from global warming, could be accelerated by subglacial volcanism. Behrendt et al., (1994; 2007) conservatively estimated >1 x 106km volume of volcanic sources to account for the area of the "volcanic center" anomalies and suggested the presence of a LIP if this volume was intruded between 1 and 10 m.y. Behrendt et. al (1992) suggested a mantle plume,which hypothesis still merits consideration.

  10. Study on Sustainable Development Capability of Shandong Province

    Institute of Scientific and Technical Information of China (English)

    Ren Ziping; Luo Qishan; Wang Yanchun; Deng Hongbing; Zhao Jingzhu

    2005-01-01

    Based on the indicator system of Sustainable Development ( SD ), Shandong Province was selected as an example for assessment with AHP method and the standard year was 1978. The conclusion was that Shandong Province' s ability of SD was being strengthened step by step, and there were also some restrictive factors, and according to the basic conditions of Shandong Province, countermeasures and strategy of SD were put forward.

  11. Political Ideology and Economic Freedom across Canadian Provinces

    DEFF Research Database (Denmark)

    Bjørnskov, Christian; Potrafke, Niklas

    This paper examines how political ideology influenced economic freedom in the Canadian provinces. We analyze the dataset of economic freedom indicators compiled by the Fraser Institute in 10 Canadian provinces over the 1981-2005 period and introduce two different indices of political ideology...... leftist and rightwing governments concerning the role of government in the economy and (2) indicates that ideological polarization concerns governments but less parliamentary fractions in the Canadian provinces. ...

  12. Measuring the competitiveness of the provinces of Ecuador

    OpenAIRE

    Alvarado, Rafael

    2011-01-01

    The aim in this paper is constructs an index of competitiveness for the provinces (PCI) in Ecuador. The CPI measures the structural and institutional conditions that cause the provinces competitiveness. This index can be used as an indicator larger than the rate of growth of GDP or per capita income to measure the productive capacity of the provinces and the standard of living of its inhabitants. Factors included are economic, human capital, geography, infrastructure, institutions and markets...

  13. 78 FR 36753 - North Atlantic Coast Comprehensive Study

    Science.gov (United States)

    2013-06-19

    ... Department of the Army; Corps of Engineers North Atlantic Coast Comprehensive Study AGENCY: Department of the Army, U.S. Army Corps of Engineers, DoD. ACTION: Notice of Study Initiation. SUMMARY: The Congressional.... The goals of the North Atlantic Coast Comprehensive Study authorized under the Disaster...

  14. 75 FR 74004 - Atlantic Highly Migratory Species; Advisory Panel

    Science.gov (United States)

    2010-11-30

    ... data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean, Gulf of Mexico... but not limited to data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean... sharks, it may be expanded to include other HMS, as needed. The primary purpose of the individuals in...

  15. 76 FR 166 - Fresh and Chilled Atlantic Salmon From Norway

    Science.gov (United States)

    2011-01-03

    ... imports of fresh and chilled Atlantic salmon from Norway (56 FR 14920, 14921). Following five-year reviews... imports of fresh and chilled Atlantic salmon from Norway (71 FR 7512). The Commission is now conducting...), as most recently amended at 74 FR 2847 (January 16, 2009). \\1\\ \\1\\ No response to this request...

  16. Local and remote impacts of a tropical Atlantic salinity anomaly

    Energy Technology Data Exchange (ETDEWEB)

    Mignot, Juliette; Frankignoul, Claude [UPMC/CNRS/IRD/MNHN, Universite Pierre et Marie Curie, IPSL/LOCEAN, Paris (France)

    2010-12-15

    The climatic impacts of an enhanced evaporation prescribed during 50 years in the tropical Atlantic are investigated in a coupled ocean-atmosphere general circulation model. Locally, the salinity increase leads to a rapid deepening and cooling of the surface mixed layer. This induces a deepening of the equatorial undercurrent and an intensification of the south equatorial current. A remote atmospheric response to the tropical Atlantic perturbation is detected in the North Atlantic sector after ten years. It has the form of a robust wave-like tropospheric perturbation seemingly excited by the weakening of atmospheric deep convection over the Amazonian basin. Meanwhile, the salt anomaly is carried northward by the mean oceanic circulation. It is traced up to the convection sites and then on its return path at depth towards lower latitudes. Consistent with the density increase, deep convection is enhanced after the arrival of the salt anomaly and the Atlantic meridional overturning circulation (AMOC) intensifies about 20 years after the beginning of the perturbation. The adjustment of the tropical Atlantic to the AMOC intensification then modifies its initial response to the freshwater forcing, leading to a weaker cooling in the northern tropical Atlantic than in the southern tropical Atlantic, a slight northward shift of the tropical Atlantic precipitation pattern and an intensification of the North Brazil current. On the other hand, no significant anomalous precipitations are found in the Pacific. The initial remote atmospheric response is also modulated, by an NAO-like response to the AMOC intensification. (orig.)

  17. Mid-Atlantic Wind - Overcoming the Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Daniel F. Ancona III; Kathryn E. George; Lynn Sparling; Bruce C. Buckheit; Daniel LoBue; and Richard P. Bowers

    2012-06-29

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  18. Mid-Atlantic Wind - Overcoming the Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Daniel F. Ancona III; Kathryn E. George; Richard P. Bowers; Dr. Lynn Sparling; Bruce Buckheit; Daniel LoBue

    2012-05-31

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  19. Seafloor Asymmetry in the Atlantic Ocean

    Institute of Scientific and Technical Information of China (English)

    S.S.Gao; K.H.Liu

    2004-01-01

    Measurements of seafloor asymmetry at about 360000 pairs of conjugate points along 1250 profiles across the mid-Atlantic Ridge(MAR)provide new constraints on models for the upwelling of the buoyant asthenosphere. The sign and amplitude of the asymmetry vary systematically and are functions of the distance between the spreading center and the location of the inferred location of maximum regional buoyancy(LMRB)in the asthenosphere. The LMRB is a smooth line derived from the observed asymmetry and is more centered at the regional topographic high than the spreading center. These observations are best explained by active upwelling of the underlying buoyant asthenosphere rather than by pressure-release melting.

  20. MACKINDER'S "HEARTLAND" THEORY AND THE ATLANTIC COMMUNITY

    OpenAIRE

    Sharapova, Sevara

    2005-01-01

    The term "Atlantic partnership" refers to the strong diplomatic and military links between the U.S. and major Western European countries such as Great Britain, Germany and France. The union established by these countries has been durable and reliable, especially during the Cold War. The European allies consistently supported the U.S. in military actions. However, in spite of dependence on the U.S., even during the Cold War the European states had many trade conflicts with the United States. N...

  1. The igneous charnockite-high-K alkali-calcic I-type granite-incipient charnockite association in Trivandrum Block, southern India

    Science.gov (United States)

    Rajesh, H. M.

    The Pan-African (640 Ma) Chengannoor granite intrudes the NW margin of the Neoproterozoic high-grade metamorphic terrain of the Trivandrum Block (TB), southern India, and is spatially associated with the Cardamom hills igneous charnockite massif (CM). Geochemical features characterize the Chengannoor granite as high-K alkali-calcic I-type granite. Within the constraints imposed by the high temperature, anhydrous, K-rich nature of the magmas, comparison with recent experimental studies on various granitoid source compositions, and trace- and rare-earth-element modelling, the distinctive features of the Chengannoor granite reflect a source rock of igneous charnockitic nature. A petrogenetic model is proposed whereby there was a period of basaltic underplating; the partial melting of this basaltic lower crust formed the CM charnockites. The Chengannoor granite was produced by the partial melting of the charnoenderbites from the CM, with subsequent fractionation dominated by feldspars. In a regional context, the Chengannoor I-type granite is considered as a possible heat source for the near-UHT nature of metamorphism in the northern part of the TB. This is different from previous studies, which favoured CM charnockite as the major heat source. The occurrence of incipient charnockites (both large scale as well as small scale) adjacent to the granite as well as pegmatites (which contain CO2, CO2-H2O, F and other volatiles), suggests that the fluids expelled from the alkaline magma upon solidification generated incipient charnockites through fluid-induced lowering of water activity. Thus the granite and associated alkaline pegmatites acted as conduits for the transfer of heat and volatiles in the Achankovil Shear Zone area, causing pervasive as well as patchy charnockite formation. The transport of CO2 by felsic melts through the southern Indian middle crust is suggested to be part of a crustal-scale fluid system that linked mantle heat and CO2 input with upward migration

  2. Subduction history of the Paleo-Pacific plate beneath the Eurasian continent: Evidence from Mesozoic igneous rocks and accretionary complex in NE Asia

    Science.gov (United States)

    Xu, W.

    2015-12-01

    Mesozoic magmatisms in NE China can be subdivided into seven stages, i.e., Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, early Early Cretaceous, late Early Cretaceous, and Late Cretaceous. Late Triassic magmatisms consist of calc-alkaline igneous rocks in the Erguna Massif, and bimodal igneous rocks in eastern margin of Eurasian continent. The former reveals southward subduction of the Mongol-Okhotsk oceanic plate, the latter reveals an extensional environment (Xu et al., 2013). Early Jurassic magmatisms are composed of calc-alkaline igneous rocks in the eastern margin of the Eurasian continent and the Erguna Massif, revealing westward subduction of the Paleo-pacific plate and southward subduction of the Mongol-Okhotsk oceanic plate (Tang et al., 2015), respectively. Middle Jurassic magmatism only occur in the Great Xing'an Range and the northern margin of the NCC, and consists of adakitic rocks that formed in crustal thickening, reflecting the closure of the Mongol-Okhotsk ocean (Li et al., 2015). Late Jurassic and early Early Cretaceous magmatisms only occur to the west of the Songliao Basin, and consist of trackyandesite and A-type of rhyolites, revealing an extensional environment related to delamination of thickened crust. The late Early Cretaceous magmatisms are widespread in NE China, and consist of calc-alkaline volcanics in eastern margin and bimodal volcanics in intracontinent, revealing westward subduction of the Paleo-pacific plate. Late Cretaceous magmatisms mainly occur to the east of the Songliao Basin, and consist of calc-alkaline volcanics in eastern margin and alkaline basalts in intracontinent (Xu et al., 2013), revealing westward subduction of the Paleo-pacific plate. The Heilongjiang complex with Early Jurassic deformation, together with Jurassic Khabarovsk complex in Russia Far East and Mino-Tamba complex in Japan, reveal Early Jurassic accretionary history. Additionally, the Raohe complex with the age of ca. 169 Ma was

  3. Evaluation of the Rural Human Settlement in Shandong Province

    Institute of Scientific and Technical Information of China (English)

    Xu Hong; Shen Meiyu; Chen Xiangxiang

    2012-01-01

    Taking Shandong Province as the research object, this paper uses the principal component analysis method to evaluate the status of the rural human settlement in Shandong Province. It establishes the evaluation index system of the rural residential environment in Shandong Province, including living environment, economy, infrastructure, public service facilities, and ecological environment, in total five comprehensive index, and 20 second~ ary indexes. Through measurement and sorting of rural human environment development level of Shandong Province in 2010, the 17 cities are divided into-excellent, good, ordinary, poor-four development areas and are analyzed based on the restriction factor in the development of the region.

  4. North Atlantic Deep Water Production during the Last Glacial Maximum

    Science.gov (United States)

    Howe, Jacob N. W.; Piotrowski, Alexander M.; Noble, Taryn L.; Mulitza, Stefan; Chiessi, Cristiano M.; Bayon, Germain

    2016-06-01

    Changes in deep ocean ventilation are commonly invoked as the primary cause of lower glacial atmospheric CO2. The water mass structure of the glacial deep Atlantic Ocean and the mechanism by which it may have sequestered carbon remain elusive. Here we present neodymium isotope measurements from cores throughout the Atlantic that reveal glacial-interglacial changes in water mass distributions. These results demonstrate the sustained production of North Atlantic Deep Water under glacial conditions, indicating that southern-sourced waters were not as spatially extensive during the Last Glacial Maximum as previously believed. We demonstrate that the depleted glacial δ13C values in the deep Atlantic Ocean cannot be explained solely by water mass source changes. A greater amount of respired carbon, therefore, must have been stored in the abyssal Atlantic during the Last Glacial Maximum. We infer that this was achieved by a sluggish deep overturning cell, comprised of well-mixed northern- and southern-sourced waters.

  5. Prenatal Care Services in Aydin Province

    Directory of Open Access Journals (Sweden)

    Erdal BESER

    2007-04-01

    Full Text Available Aim of the study was to evaluate the quality and quantity of prenatal care in Aydin province. It was a cross-sectional study. 195 women (pregnant/women at postpartum period living in the Aydin province participated in the study. Cluster and simple random sampling method was used in the selection of women from 10 health centers (one rural-one urban health station each. Data obtained by face to face interview technique. Turkey Demografic Health Survey criteria were used for evaluation of the quantity of prenatal care as “sufficient” or “insufficient” and quality of prenatal care was scored as “1-2”(bad, “3-4”(moderate and “5-6”(good. Chi-square, Mann Whitney-U and t tests were used for analysis. One fifth of each pregnant women who were in last trimester and 11.3% of women in postpartum period stated that they were not followed up by an health personnel during pregnancy. One third of pregnant women who were in last trimester and 58.5% of women in postpartum period said they weren’t visited by an health personnel in the first trimester. Besides, quality points of prenatal care were found low, both in pregnant women and women in post partum period. It was found that living in urban areas, high education level and presence of social security effected getting adequate prenatal care. The quality and quantity of prenatal care was found less than expected in Aydin province which is located in the western region of Turkey. It is necessary that, health personnel must be more sensitive to convey “adequate” prenatal care especially women who are living in rural areas, who have low educational level and who have no social security. [TAF Prev Med Bull. 2007; 6(2: 137-141

  6. 75 FR 12507 - Fisheries of the South Atlantic and Gulf of Mexico; South Atlantic Fishery Management Council...

    Science.gov (United States)

    2010-03-16

    ...The South Atlantic Fishery Management Council (SAFMC) will hold a meeting of its Scientific and Statistical Committee (SSC) to make fishing level recommendations for black and red grouper, discuss Acceptable Biological Catch (ABC) Control Rules, and recommend ABC values for South Atlantic managed species. The meeting will be held in North Charleston,...

  7. Air-sea CO2 fluxes in the Atlantic as measured during the FICARAM cruises

    Directory of Open Access Journals (Sweden)

    A. F. Ríos

    2009-06-01

    Full Text Available A total of fourteen hydrographic cruises spanning from 2000 to 2008 were conducted during the spring and autumn seasons between Spain and the Southern Ocean, under the framework of the Spanish research project FICARAM. The performed underway measurements are processed and analysed to describe the meridional air-sea CO2 fluxes (FCO2 along the Atlantic Ocean. The data was organised into different biogeochemical oceanographic provinces, according mainly to the thermohaline characteristics. The obtained spatial and temporal distributions of FCO2 follow the generally expected patterns and annual trends. The Subtropical regions in both hemispheres alternated the CO2 source and sink nature from autumn to spring, respectively. On the other hand, Tropical waters and the Patagonian Sea clearly behaved as sinks of atmospheric CO2 like the waters of the Drake Passage during autumn. The obtained results during the cruises also revealed significant long-term trends, such as the warming of equatorial waters (0.11±0.03°C yr−1 and the decrease of surface salinity (−0.16±0.01 yr−1 in tropical waters caused by the influence of the Amazon River plume. This reduction in surface salinity appears to have a direct influence over the CO2 storage rates, fostering the uptake capacity of atmospheric CO2 (−0.09±0.03 mol m−2 yr−1. An analysis of the biogeochemical forcing on the CO2 fugacity (fCO2 variability performed from an empirical algorithm highlighted the major role of the Amazon River input in the tropical North Atlantic fluxes. In addition, it has provided a quantitative measure of the importance of the thermodynamic control of FCO2 at temperate latitudes.

  8. Primary colonization and breakdown of igneous rocks by endemic, succulent elephant trees ( Pachycormus discolor) of the deserts in Baja California, Mexico

    Science.gov (United States)

    Bashan, Yoav; Vierheilig, Horst; Salazar, Bernardo G.; de-Bashan, Luz E.

    2006-07-01

    Trees growing in rocks without soil are uncommon. In two arid regions in Baja California, Mexico, field surveys found large numbers of rock-colonizing elephant trees ( Pachycormus discolor (Benth.) Coville ex Standl. (Mexican name: copalquin) growing in igneous rocks (granite and basalt) as primary colonizers without the benefit of soil or with a very small amount of soil generated by their own growth. Many adult trees broke large granite boulders and were capable of wedging, growing in, and colonizing rocks and cliffs made of ancient lava flows. This is the first record of a tree species, apart from the previously recorded cacti, capable of primary colonization of rocks and rock rubble in hot deserts.

  9. Petrogenesis of the Late Cretaceous Demirköy Igneous Complex in the NW Turkey: Implications for magma genesis in the Strandja Zone

    Science.gov (United States)

    Karacık, Zekiye; Tüysüz, Okan

    2010-02-01

    The Srednogorie Zone in Bulgaria and its eastern continuation in NW Turkey, the Strandja Zone, consist of a Late Cretaceous magmatic belt comprised of plutonic, volcanic and associated volcano-sedimentary rocks. The Demirköy Igneous Complex is the biggest Cretaceous pluton within the Strandja Zone, and its age is between 71 and 84 Ma. The Demirköy pluton and additional smaller plutons are intruded into Triassic and older metamorphic basement rocks. A contact metamorphic aureole with hornblende-hornfels facies conditions was developed around the Demirköy pluton. The WNW-trending Demirköy pluton has an elliptical shape and a concentrically zoned internal structure. In this structure, gabbro/diorites and quartz diorites are only seen in the SW corner of the pluton, while granodiorites form the main body of the pluton surrounded by a zone of granite. The granodiorites contain dioritic mafic microgranular enclaves. Small quartz monzonite lenses and/or bodies and mafic dykes are also observed in the Demirköy Igneous Complex. Geochemically, the Demirköy Igneous Complex has calc-alkaline, metaluminous and medium-K characteristics. There is a significant correlation between the LREE/HREE ratios and SiO 2 values. Chondrite-normalized REE patterns are relatively flat (La N/Lu N = 2) in gabbros. This ratio ranges from 3 to 11 for the diorite/granodiorites, and from 14 to 35 for the granites. Dioritic enclaves have REE patterns similar to those of the main body and have La N/Lu N values between 3 and 6. Relatively enriched LILE (Sr, K, Rb, Ba and Th) and relatively depleted HFSE (Ta, Nb and Ti) values indicate the classic subduction-related origin of the complex. The initial isotopic signatures range from ɛNd( i) = - 0.45 to - 2.57 and 87Sr/ 86Sr( i) = 0.7042-0.7064 for gabbros and ɛNd( i) = - 0.43 to - 2.67 and 87Sr/ 86Sr( i) = 0.7048-0.7059 for granodiorites and granites. δ18O values range from + 6.18 to + 7.80‰ (VSMOW) for gabbros and from + 6.86 to + 8.89

  10. Kinematics of the South Atlantic rift

    CERN Document Server

    Heine, Christian; Müller, R Dietmar

    2013-01-01

    The South Atlantic rift basin evolved as branch of a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. By quantitatively accounting for crustal deformation in the Central and West African rift zone, we indirectly construct the kinematic history of the pre-breakup evolution of the conjugate West African-Brazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic Pre-salt sag basin and the S\\~ao Paulo High. We model an initial E-W directed extension between South America and Africa (fixed in present-day position) at very low extensional velocities until Upper Hauterivian times ($\\approx$126 Ma) when rift activity along in the equatorial Atlantic domain started to increase significantly. During this initial $\\approx$17 Myr-long stretching episode the Pre-salt basin width on the conjugate Br...

  11. The enigmatic whale: the North Atlantic humpback

    Directory of Open Access Journals (Sweden)

    Tim D Smith

    2013-10-01

    Full Text Available We know more about the North Atlantic humpback whale (Megaptera novaeangliae than we do for virtually any other cetacean, yet attempts to use this information to describe the status of the populations in this ocean basin have not proven satisfactory. The North Atlantic humpback has been the subject of extensive research over the past few decades, resulting in a substantial amount of knowledge about what has proven to be a species with a very complex life history and population structure. While several population models have been developed to integrate the available information, the data overall are not well described by any of the models. This has left considerable uncertainty about population status, and has raised questions about the interpretation of some of the data. We describe 7 specific areas where puzzling or ambiguous observations have been made; these require closer attention if population status is to be determined. These areas raise several fundamental questions, including: How many breeding populations are there? How much do the populations mix on the feeding grounds? How has the distribution of animals on both feeding and breeding grounds changed? We identify additional research needed to address the 7 areas and these questions in particular, so that population status might be determined.

  12. Arc-continent collision and the formation of continental crust: A new geochemical and isotopic record from the Ordovician Tyrone Igneous Complex, Ireland

    Science.gov (United States)

    Draut, Amy E.; Clift, Peter D.; Amato, Jeffrey M.; Blusztajn, Jerzy; Schouten, Hans

    2009-01-01

    Collisions between oceanic island-arc terranes and passive continental margins are thought to have been important in the formation of continental crust throughout much of Earth's history. Magmatic evolution during this stage of the plate-tectonic cycle is evident in several areas of the Ordovician Grampian-Taconic orogen, as we demonstrate in the first detailed geochemical study of the Tyrone Igneous Complex, Ireland. New U-Pb zircon dating yields ages of 493 2 Ma from a primitive mafic intrusion, indicating intra-oceanic subduction in Tremadoc time, and 475 10 Ma from a light rare earth element (LREE)-enriched tonalite intrusion that incorporated Laurentian continental material by early Arenig time (Early Ordovician, Stage 2) during arc-continent collision. Notably, LREE enrichment in volcanism and silicic intrusions of the Tyrone Igneous Complex exceeds that of average Dalradian (Laurentian) continental material that would have been thrust under the colliding forearc and potentially recycled into arc magmatism. This implies that crystal fractionation, in addition to magmatic mixing and assimilation, was important to the formation of new crust in the Grampian-Taconic orogeny. Because similar super-enrichment of orogenic melts occurred elsewhere in the Caledonides in the British Isles and Newfoundland, the addition of new, highly enriched melt to this accreted arc terrane was apparently widespread spatially and temporally. Such super-enrichment of magmatism, especially if accompanied by loss of corresponding lower crustal residues, supports the theory that arc-continent collision plays an important role in altering bulk crustal composition toward typical values for ancient continental crust. ?? 2009 Geological Society of London.

  13. New zircon data supporting models of short-lived igneous activity at 1.89 Ga in the western Skellefte District, central Fennoscandian Shield

    Directory of Open Access Journals (Sweden)

    P. Skyttä

    2011-10-01

    Full Text Available New U-Th-Pb zircon data (SIMS from three intrusive phases of the Palaeoproterozoic Viterliden intrusion in the western Skellefte District, central Fennoscandian Shield, dates igneous emplacement in a narrow time interval at about 1.89 Ga. A locally occurring quartz-plagioclase porphyritic tonalite, here dated at 1889 ± 3 Ma, is considered the youngest of the intrusive units, based on the new age data and field evidence. This supports an existing interpretation of its fault-controlled emplacement after intrusion of the dominating hornblende-tonalite units, in this study dated at 1892 ± 3 Ma. The Viterliden magmatism was synchronous with the oldest units of the Jörn type early-orogenic intrusions in the eastern part of the district (1.89–1.88 Ga; cf. Gonzàles Roldán, 2010. A U-Pb zircon age for a felsic metavolcanic rock from the hanging-wall to the Kristineberg VMS deposit, immediately south of the Viterliden intrusion, is constrained at 1883 ± 6 Ma in this study. It provides a minimum age for the Kristineberg ore deposit and suggests contemporaneous igneous/volcanic activity throughout the Skellefte District. Furthermore, it supports the view that the Skellefte Group defines a laterally continuous belt throughout this "ore district". Tentative correlation of the 1889 ± 3 Ma quartz-plagioclase porphyritic tonalite with the Kristineberg "mine porphyry" suggests that these units are coeval at about 1.89 Ga. Based on the new age determinations, the Viterliden intrusion may equally well have intruded into or locally acted as a basement for the ore-hosting Skellefte Group volcanic rocks.

  14. New zircon data supporting models of short-lived igneous activity at 1.89 Ga in the western Skellefte District, central Fennoscandian Shield

    Directory of Open Access Journals (Sweden)

    P. Skyttä

    2011-04-01

    Full Text Available New U-Th-Pb zircon data (SIMS from three intrusive phases of the Palaeoproterozoic Viterliden intrusion in the western Skellefte District, central Fennoscandian Shield, dates igneous emplacement in a narrow time interval at about 1.89 Ga. A locally occurring quartz-plagioclase porphyritic tonalite, here dated at 1889 ± 3 Ma, is, based on the new age data and field evidence, considered the youngest of the intrusive units. This supports an existing interpretation of its fault-controlled emplacement after intrusion of the dominating hornblende-tonalite units, in this study dated at 1892 ± 3 Ma. The Viterliden magmatism was synchronous with the oldest units of the Jörn type early-orogenic intrusions in the eastern part of the district (1.89–1.88 Ga; cf. Gonzàles Roldán, 2010. A U-Pb zircon age for a felsic metavolcanic rock from the hanging-wall to the Kristineberg VMS deposit, immediately south of the Viterliden intrusion, is in this study constrained in the 1.89–1.88 Ga time interval. It provides a minimum age for the Kristineberg ore deposit and suggests contemporaneous igneous/volcanic activity throughout the Skellefte District. Furthermore, it supports the view that the Skellefte Group defines a laterally continuous belt throughout this "ore district". Tentative correlation of the 1889 ± 3 Ma quartz-plagioclase porphyritic tonalite with the Kristineberg "mine porphyry", which cuts the altered ore-hosting metavolcanic rocks, further constrain the minimum age for ore deposition at 1889 ± 3 Ma. Based on the new age determinations, the Viterliden intrusion may equally well have intruded into, or locally acted as a basement for the ore-hosting Skellefte Group volcanic rocks.

  15. Rb-Sr and Sm-Nd isotopic and REE studies of igneous components in the bulk matrix domain of Martian breccia Northwest Africa 7034

    Science.gov (United States)

    Nyquist, Laurence E.; Shih, Chi-Yu; McCubbin, Francis M.; Santos, Alison R.; Shearer, Charles K.; Peng, Zhan X.; Burger, Paul V.; Agee, Carl B.

    2016-03-01

    The bulk matrix domain of the Martian breccia NWA 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia. Both 147Sm-143Nd and 146Sm-142Nd age results for mineral separates from the bulk matrix portion of breccia NWA 7034 suggest that various lithological components in the breccia probably formed contemporaneously ~4.44 Ga ago. This old age is in excellent agreement with the upper intersection ages (4.35-4.45 Ga) for U-Pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous-textured clasts. Consequently, we confirm an ancient age for the igneous components that make up the NWA 7034 breccia. Substantial disturbance in the Rb-Sr system was detected, and no age significance could be gleaned from our Rb-Sr data. The disturbance to the Rb-Sr system may be due to a thermal event recorded by bulk-rock K-Ar ages of 1.56 Ga and U-Pb ages of phosphates at about 1.35-1.5 Ga, which suggest partial resetting from an unknown thermal event(s), possibly accompanying breccia formation. The NWA 7034 bulk rock is LREE enriched and similar to KREEP-rich lunar rocks, which indicates that the earliest Martian crust was geochemically enriched. This enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on Mars that have been detected in studies of other Martian meteorites.

  16. Towards a model of postglacial biogeography in shallow marine species along the Patagonian Province: lessons from the limpet Nacella magellanica (Gmelin, 1791

    Directory of Open Access Journals (Sweden)

    González-Wevar Claudio A

    2012-08-01

    Full Text Available Abstract Background Patagonia extends for more than 84,000 km of irregular coasts is an area especially apt to evaluate how historic and contemporary processes influence the distribution and connectivity of shallow marine benthic organisms. The true limpet Nacella magellanica has a wide distribution in this province and represents a suitable model to infer the Quaternary glacial legacy on marine benthic organisms. This species inhabits ice-free rocky ecosystems, has a narrow bathymetric range and consequently should have been severely affected by recurrent glacial cycles during the Quaternary. We performed phylogeographic and demographic analyses of N. magellanica from 14 localities along its distribution in Pacific Patagonia, Atlantic Patagonia, and the Falkland/Malvinas Islands. Results Mitochondrial (COI DNA analyses of 357 individuals of N. magellanica revealed an absence of genetic differentiation in the species with a single genetic unit along Pacific Patagonia. However, we detected significant genetic differences among three main groups named Pacific Patagonia, Atlantic Patagonia and Falkland/Malvinas Islands. Migration rate estimations indicated asymmetrical gene flow, primarily from Pacific Patagonia to Atlantic Patagonia (Nem=2.21 and the Falkland/Malvinas Islands (Nem=16.6. Demographic reconstruction in Pacific Patagonia suggests a recent recolonization process ( Conclusions Absence of genetic structure, a single dominant haplotype, lack of correlation between geographic and genetic distance, high estimated migration rates and the signal of recent demographic growth represent a large body of evidence supporting the hypothesis of rapid postglacial expansion in this species in Pacific Patagonia. This expansion could have been sustained by larval dispersal following the main current system in this area. Lower levels of genetic diversity in inland sea areas suggest that fjords and channels represent the areas most recently colonized by

  17. Hydrogeologic Provinces for California based upon established groundwater basins and watershed polygons.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Ten hydrogeologic provinces of California are represented by a region- class feature called "provinces" within this digital data set. These provinces were...

  18. Cancer survival in Khon Kaen Province, Thailand.

    Science.gov (United States)

    Sriamporn, S; Black, R J; Sankaranarayanan, R; Kamsa-ad, S; Parkin, D M; Vatanasapt, V

    1995-05-01

    Thailand is one of the few developing countries for which population-based cancer survival data are available. Using clinical follow-up information and reply-paid postal enquiries, 10,333 residents of Khon Kaen province registered with cancer in the period 1985-1992 were followed-up to the end of 1993. The sites of the most common cancers in the province were liver (5-year relative survival rate 9.2%), cervix (60.1%), lung (15.4%), breast (48.1%) and large bowel (41.9%). Results for Khon Kaen were compared with age-standardized survival data for the US and Scotland. Survival was consistently higher for US whites compared to Khon Kaen residents for those cancers whose prognosis is associated with early diagnosis (breast, cervix and large bowel) or the availability of intensive therapy (leukaemia and lymphoma). The main implication of these results for cancer control in Thailand is that the interventions of greatest potential benefit are those designed to promote early detection. More than one-third of all cancers in Thailand are liver tumours: primary prevention through control of hepatitis-B infection and liver fluke infestation is the only effective strategy for their control. PMID:7729937

  19. A catch history for Atlantic walruses (Odobenus rosmarus rosmarus in the eastern Canadian Arctic

    Directory of Open Access Journals (Sweden)

    D Bruce Stewart

    2014-08-01

    Full Text Available Knowledge of changes in abundance of Atlantic walruses (Odobenus rosmarus rosmarus in Canada is important for assessing their current population status. This catch history collates available data and assesses their value for modelling historical populations to inform population recovery and management. Pre-historical (archaeological, historical (e.g., Hudson Bay Company journals and modern catch records are reviewed over time by data source (whaler, land-based commercial, subsistence etc. and biological population or management stock.Direct counts of walruses landed as well as estimates based on hunt products (e.g., hides, ivory or descriptors (e.g., Peterhead boatloads support a minimum landed catch of over 41,300 walruses in the eastern Canadian Arctic between 1820 and 2010. Little is known of Inuit catches prior to 1928, despite the importance of walruses to many Inuit groups for subsistence. Commercial hunting from the late 1500s to late 1700s extirpated the Atlantic walrus from Quebec and the Atlantic Provinces, but there was no commercial hunt for the species in the Canadian Arctic until ca. 1885. As the availability of bowhead whale (Balaena mysticetus declined, whalers increasingly turned to hunting other species, including walruses. Modest numbers (max. 278/yr were taken from the High Arctic population in the mid-1880s and large catches (up to 1400/yr were often taken from the Central Arctic population from 1899 -1911, while the Foxe Basin stock (Central Arctic population and Low Arctic population were largely ignored by commercial hunters. Land-based traders (ca. 1895-1928 continued the commercial hunt until regulatory changes in 1928 reserved walruses for Inuit use. Since 1950, reported walrus catches have been declining despite a steady increase in the Inuit population. Effort data are needed to assess whether lower catches stem from declining hunter effort or decreased walrus abundance. The recent take of walruses by sport hunting

  20. Guide the Construction of Ecological Province of China with the Ecological Economics Theory

    Institute of Scientific and Technical Information of China (English)

    WangSongpei

    2005-01-01

    A major issue in China's present ecological economic construction is to build the ecological province. In March of 1999,Hainan Province of China proposed setting up the first ecological province and was accredited by the Bureau of State Environment Protection as the pilot project. Up to now for only four years, Hainan, Jilin, Heilongjiang, Fujian, Zhejiang,Shandong, Anhui, Jiangsu, eight provinces in the wholecountry, having launched the establishment of the ecological province. Meanwhile, the provinces such as Shaanxi, Hebei,

  1. STATISTICAL SUMMARY: EMAP-ESTUARIES LOUISIANIAN PROVINCE - 1993

    Science.gov (United States)

    This statistical summmary of the ecological condition of the estuarine resources is based on the results of the 1993 Louisianian Province Demonstration Project. The population of estuarine resources with the Louisianian Province consists of all estuarine areas located along the c...

  2. Integrated Coastal Management in the Province Ca Mau - Vietnam

    NARCIS (Netherlands)

    Stoop, B.; Bouziotas, D.; Hanssen, J.L.J.; Dunnewolt, J.; Postma, M.G.

    2015-01-01

    The province of Ca Mau is the southernmost part of Vietnam and the Mekong Delta. The water system of Ca Mau faces multiple challenges, both in its coastal zone and in its inland regions. the coastal zone in the province. In view of this, this study presents an integrated approach for combined coasta

  3. Province of Ontario nuclear emergency plan. Pt. 1

    International Nuclear Information System (INIS)

    The Province of Ontario Nuclear Emergency Plan has been developed pursuant to Section 8 of the Emergency Plans Act, 1983. This plan replaces the Province of Ontario Nuclear Contingency Off-Site Plan (June 1980) which is no longer applicable. The wastes plan includes planning, preparation, emergency organization and operational responsibilities and policy

  4. Review on wheat mutation breeding in Shandong province

    International Nuclear Information System (INIS)

    The history, achievements and current status of wheat mutation breeding in Shandong province are briefly reviewed. The common used techniques and steps for mutation breeding of wheat are introduced. Suggestions and prospect of wheat mutation breeding in Shandong province are listed. (authors)

  5. Measuring Convergence using Dynamic Equilibrium Models: Evidence from Chinese Provinces

    DEFF Research Database (Denmark)

    Pan, Lei; Posch, Olaf; van der Wel, Michel

    determine equilibrium dynamics. The inference on the structural parameters is done using a maximum-likelihood approach. We estimate our model using growth and population data for China’s provinces from 1978 to 2010. We report heterogeneity in the speed of convergence both across provinces and time. The...

  6. Developmental Strategies of Betel Nut Industry in Hainan Province

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The developmental status of the betel nut industry is introduced, including cultivation situation, processing and development situation, and consumer market situation. The result shows that the cultivation of betel nut in Hainan Province develops rapidly and the primary processing of betel nut has formed certain scale, but the deep processing of betel nut is backward. Except for the mino amount of the betel nuts consumed by Hainan Island, a large majority of the betel nuts are processed into dry fruit to sell to Hunan Province to reprocess. The problems exist in the development of betel nut industry in Hainan Province are analyzed, covering blind cultivation, extensive management, backward processing, lagged new product development and the single and concentrated consumer market. The strategic choice of developing the betel nut industry of Hainan Province is analyzed as well. Hainan Province should carry out the green, sustainable, diversified, cooperative and export-oriented industrial developmental strategy.

  7. The Development Model of Agricultural Insurance in Anhui Province

    Institute of Scientific and Technical Information of China (English)

    Pu; YOU

    2014-01-01

    The agricultural economy in Anhui Province is developing so fast,but farmers are severely affected by the frequent occurrence of natural disasters. The current agricultural insurance mode is not suitable,therefore,the research on agricultural insurance modes of Anhui Province helps to promote the steady development of the agricultural production. Starting from situation of agricultural insurance in Anhui Province,learning from both experience of foreign country and the latest successful domestic modes,we try to put forward agricultural insurance mode framework which is suitable for Anhui Province. Based on the actual situation of Anhui Province,it is necessary to adopt the mode of government leading combined with agricultural mutual aid rather than copy the existing mode.

  8. Atlante project; Progetto atlante. Quadro di riferimento, analisi degli strumenti esistenti, implementazione metodologica e applicazione prototipale

    Energy Technology Data Exchange (ETDEWEB)

    Baratozzi, L.; Cagnoli, P.; Filippi, N.; Gherardi, L.; Montaletti, V.; Poli, G.; Scarelli, M. [Regione Emilia Romagna, Assessorato Territorio, Programmazione e Ambiente, Servizio Paesaggio, Parchi e Patrimonio Naturale, Bologna (Italy); Basili, M.; Battista, A.; Colonna, R.; Del Cellio, R.; Forni, A.; Olivetti, I.; Regina, P.; Zarlenga, F. [ENEA, Divisione Caratterizzazione dell' Ambiente e del Territorio, Centro Ricerche della Casaccia, S. Maria di Galeria, RM (Italy)

    2001-07-01

    This paper presents the Atlante project a joint program of Emilia Romagna region and Italian ENEA based on the concept of substantiality and the most important methods and models used in the territorial planning. [Italian] La redazione del presente volume e' stata articolata in modo da bilanciare, da un lato l'esigenza di rispettare il programma di attivita' previsto nell'ambito della Convenzione fra Regione Emilia Romagna ed ENEA.

  9. Analysing migrations of Atlantic cod Gadus morhua in the north‐east Atlantic Ocean

    DEFF Research Database (Denmark)

    Neuenfeldt, S.; Righton, D.; Neat, F.;

    2013-01-01

    be measured directly but has to be estimated using the available data on light, temperature, pressure and salinity. The reconstructed locations based on advanced estimation techniques have been termed geolocations. Examples are discussed which illustrate the applicability of geolocations in...... state-of-the-art geolocations for cod Gadus morhua in the north-east Atlantic Ocean, the major aim of this review is to raise awareness of gaps in knowledge and to identify ideas for new research...

  10. South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event

    OpenAIRE

    Ljung, K.; Björck, S.; Renssen, H.; D. Hammarlund

    2007-01-01

    International audience One of the most distinct climate fluctuations during the Holocene is the short and rapid event centred around 8200 years ago, the 8.2 kyr event, which was most likely triggered by glacial melt-water forcing from the receding Laurentide ice-sheet. Evidence for this cooling has primarily been reported from sites around the North Atlantic, but an increasing number of observations imply a more wide-spread occurrence. Palaeoclimate archives from the Southern Hemisphere ha...

  11. Estimation of Atlantic-Mediterranean netflow variability

    Science.gov (United States)

    Guerreiro, Catarina; Peliz, Alvaro; Miranda, Pedro

    2016-04-01

    The exchanges at the Strait of Gibraltar are extremely difficult to measure due to the strong temporal and across-strait variabilities; yet the Atlantic inflow into the Mediterranean is extremely important both for climate and to ecosystems. Most of the published numerical modeling studies do not resolve the Strait of Gibraltar realistically. Models that represent the strait at high resolution focus primarily in high frequency dynamics, whereas long-term dynamics are studied in low resolution model studies, and for that reason the Strait dynamics are poorly resolved. Estimating the variability of the exchanges requires long term and high-resolutions studies, thus an improved simulation with explicit and realistic representation of the Strait is necessary. On seasonal to inter-annual timescales the flow is essentially driven by the net evaporation contribution and consequently realistic fields of precipitation and evaporation are necessary for model setup. A comparison between observations, reanalysis and combined products shows ERA-Interim Reanalysis has the most suitable product for Mediterranean Sea. Its time and space variability are in close agreement with NOC 1.1 for the common period (1980 - 1993) and also with evaporation from OAFLUX (1989 - 2014). Subinertial fluctuations, periods from days to a few months, are the second most energetic, after tides, and are the response to atmospheric pressure fluctuations and local winds. Atmospheric pressure fluctuations in the Mediterranean cause sea level oscillations that induce a barotropic flow through the Strait. Candela's analytical model has been used to quantify this response in later studies, though comparison with observations points to an underestimation of the flow at strait. An improved representation of this term contribution to the Atlantic - Mediterranean exchange must be achieved on longer time-scales. We propose a new simulation for the last 36 years (1979 - 2014) for the Mediterranean - Atlantic

  12. Population Structure of the Rockpool Blenny Entomacrodus vomerinus Shows Source-Sink Dynamics among Ecoregions in the Tropical Southwestern Atlantic.

    Directory of Open Access Journals (Sweden)

    Jessika M M Neves

    Full Text Available The Tropical Southwestern Atlantic is characterized by prominent ecosystems with large-scale oceanographic complexity. Yet, the evolutionary processes underlying genetic differentiation and connectivity in this region remain largely unknown. Entomacrodus vomerinus (Valenciennes, 1836 is a demersal fish with planktonic larvae endemic to this marine province, inhabiting shallow tidal pools in continental and oceanic reef environments. We evaluated the population structure, genetic diversity and gene flow of E. vomerinus using mitochondrial data (CYTB and COI and nuclear (rhodopsin, RHO DNA sequences. We sampled a total of 85 individuals, comprising 46 from three oceanic archipelagos with varying distance from the coast (São Pedro and São Paulo-SS, Fernando de Noronha-FE and Rocas Atoll-RA and 39 from two localities in northeastern Brazilian coast (Rio Grande do Norte-RN and Bahia-BA. Multilocus analysis revealed the presence of three Evolutionarily Significant Units-ESUs (SS, FE+RA, and RN+BA, which are in accordance with distinct marine ecoregions. Coalescent analyses showed that the central ESU has a larger effective population size than the other two, suggesting strong asymmetries in the genetic diversity across the species range. Moreover, they showed that gene flow is highly asymmetric, suggesting a source-sink dynamics from the central ESU into the remaining ones, in agreement with oceanic currents. Together, these results provide insights in the evolutionary mechanisms facilitating diversification in this marine province.

  13. Population Structure of the Rockpool Blenny Entomacrodus vomerinus Shows Source-Sink Dynamics among Ecoregions in the Tropical Southwestern Atlantic.

    Science.gov (United States)

    Neves, Jessika M M; Lima, Sergio M Q; Mendes, Liana F; Torres, Rodrigo A; Pereira, Ricardo J; Mott, Tamí

    2016-01-01

    The Tropical Southwestern Atlantic is characterized by prominent ecosystems with large-scale oceanographic complexity. Yet, the evolutionary processes underlying genetic differentiation and connectivity in this region remain largely unknown. Entomacrodus vomerinus (Valenciennes, 1836) is a demersal fish with planktonic larvae endemic to this marine province, inhabiting shallow tidal pools in continental and oceanic reef environments. We evaluated the population structure, genetic diversity and gene flow of E. vomerinus using mitochondrial data (CYTB and COI) and nuclear (rhodopsin, RHO) DNA sequences. We sampled a total of 85 individuals, comprising 46 from three oceanic archipelagos with varying distance from the coast (São Pedro and São Paulo-SS, Fernando de Noronha-FE and Rocas Atoll-RA) and 39 from two localities in northeastern Brazilian coast (Rio Grande do Norte-RN and Bahia-BA). Multilocus analysis revealed the presence of three Evolutionarily Significant Units-ESUs (SS, FE+RA, and RN+BA), which are in accordance with distinct marine ecoregions. Coalescent analyses showed that the central ESU has a larger effective population size than the other two, suggesting strong asymmetries in the genetic diversity across the species range. Moreover, they showed that gene flow is highly asymmetric, suggesting a source-sink dynamics from the central ESU into the remaining ones, in agreement with oceanic currents. Together, these results provide insights in the evolutionary mechanisms facilitating diversification in this marine province. PMID:27309356

  14. Delimiting oceanographic provinces to determine drivers of mesoscale patterns in benthic megafauna: A case study in the Barents Sea

    Science.gov (United States)

    Lacharité, Myriam; Jørgensen, Lis Lindal; Metaxas, Anna; Lien, Vidar S.; Skjoldal, Hein Rune

    2016-08-01

    Communities of benthic megafauna in the deep waters of continental shelves (> 100 m) are important components of marine ecosystems. In high-latitude ecosystems, this fauna is increasingly impacted by human activities and climate variability. In this study, we provide baseline knowledge on the oceanographic conditions affecting its distribution in the Barents Sea in the vicinity of the Polar Front - an oceanic front occurring at the transition zone between the Atlantic and Arctic water masses. We used fields of temperature and currents from an ocean circulation model (Regional Ocean Modelling System - ROMS) to derive variables divided into 3 groups relevant to bottom fauna (temperature, water column structure and bottom currents) expressing either mean conditions or temporal variability over 10 years (2001-2010). Benthic megafauna was surveyed in summer 2011 at 139 sites. To analyze the relationship between spatial variability in the composition of benthic megafauna (i.e., β-diversity) and oceanographic conditions, we: (1) used generalized dissimilarity modelling (GDM) and (2) delimited oceanographic provinces (i.e., regions of similar conditions) for each group of variables using principal component analysis (PCA) followed by cluster analysis. Turnover in benthic megafauna was explained by 7 oceanographic variables (temperature: 4, water column structure: 2, bottom currents: 1), depth and geographic distance (56.7% of total deviance explained). Concurrently, patterns in oceanographic provinces among the 3 groups of variables coincided with results from the GDM, where provinces derived from temperature were sharply delimited relative to the other groups. We concluded that the spatial structure of the environment is important in the relationship between spatial variability of benthic megafauna and oceanographic conditions in shelf deep waters. Ocean models are powerful tools to study this relationship, but the way in which their inherent uncertainty affects the

  15. South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event

    Directory of Open Access Journals (Sweden)

    K. Ljung

    2007-05-01

    Full Text Available One of the most distinct climate fluctuations during the Holocene is the short and rapid event centred around 8200 years ago, the 8.2 kyr event, which was most likely triggered by glacial melt-water forcing from the receding Laurentide ice-sheet. Evidence for this cooling has primarily been reported from sites around the North Atlantic, but an increasing number of observations imply a more wide-spread occurrence. Palaeoclimate archives from the Southern Hemisphere have hitherto failed to uncover a distinct climatic anomaly associated with the 8.2 kyr event. Here we present a lake sediment record from Nightingale Island in the central South Atlantic showing enhanced precipitation between 8275 and 8025 cal. yrs BP, most likely as a consequence of increased sea surface temperature (SST. We show that this is consistent with climate model projections of a warming of the South Atlantic in response to reduced north-ward energy transport during the 8.2 kyr event.

  16. Observations and Modeling of the Atlantic Meridional Mode during the Atlantic hurricane season

    Science.gov (United States)

    Smirnov, D.; Vimont, D. J.

    2009-12-01

    An observational and modeling study is conducted to investigate the vertical structure of the Atlantic Meridional Mode (AMM) during the Atlantic hurricane season months based on an AMM index derived by Chiang and Vimont (2004). The analysis shows that the SST anomaly structure that is typically associated with the AMM is accompanied by a slackening (intensification) of trade winds in the Northern (Southern) Hemisphere where SST anomalies are positive (negative). However, the accompanying air temperature anomalies are limited to the boundary layer. Furthermore, the AMM is shown to be associated with an anomalous baroclinic circulation in the northern subtropical Atlantic, with an anomalous lower-level cyclonic circulation residing under an anomalous upper-level anticyclone during a positive AMM. Initializing the atmospheric GCM CAM3.1 coupled to a slab ocean with AMM-like SST anomalies yields an atmospheric circulation that is highly similar to observational analyses. This suggests that the SST anomalies are forcing the atmospheric anomalies, and not vice versa. The anomalous atmospheric circulations of the lower and upper-levels act in tandem to reduce shear over the main development region (MDR), reiterating that a positive AMM favors increased hurricane activity in the MDR. A closer inspection of the monthly evolution of shear shows that the response increases three-fold from September to November within the MDR. However, the origin of the SST anomalies, which is vital in improving seasonal hurricane activity predictions, remains unclear.

  17. South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event

    Directory of Open Access Journals (Sweden)

    K. Ljung

    2008-02-01

    Full Text Available One of the most distinct climate fluctuations during the Holocene is the short and rapid event centred around 8200 years ago, the 8.2 kyr event, which was most likely triggered by glacial melt-water forcing from the receding Laurentide ice-sheet. Evidence for this cooling has primarily been reported from sites around the North Atlantic, but an increasing number of observations imply a more wide-spread occurrence. Palaeoclimate archives from the Southern Hemisphere have hitherto failed to uncover a distinct climatic anomaly associated with the 8.2 kyr event. Here we present a lake sediment record from Nightingale Island in the central South Atlantic showing enhanced precipitation between 8275 and 8025 cal. yrs BP, most likely as a consequence of increased sea surface temperature (SST. We show that this is consistent with climate model projections of a warming of the South Atlantic in response to reduced north-ward energy transport during the 8.2 kyr event.

  18. Y-STR genetic diversity in autochthonous Andalusians from Huelva and Granada provinces (Spain).

    Science.gov (United States)

    Ambrosio, Beatriz; Novelletto, Andrea; Hernandez, Candela; Dugoujon, Jean Michel; Fortes-Lima, César; Rodriguez, Juan Nicolás; Calderon, Rosario

    2012-03-01

    Seventeen Y-chromosomal short tandem repeats (STRs) were analyzed in 347 healthy, unrelated, autochthonous males from the Andalusian provinces of Huelva (N=167) and Granada (N=180). AmpFlSTR Y-filer PCR Amplification kit (Applied Biosystems) was used to type the Y-STR markers. A total of 156 and 166 different haplotypes for the 17 Y-STR set were detected in Huelva, and Granada, respectively. The same haplotype diversity was found for both samples (0.998±0.001), and the overall discrimination capacity was 0.904. The most common minimal haplotype (DYS19, DYS389 I, DYS389 II, DYS390, DYS391, DYS392, DYS393) in both subpopulations was 14-13-16-24-11-13-13, which is also the most frequent haplotype among Atlantic European populations. Comparison analysis using pairwise R(ST) values and Analysis of Molecular Variance (AMOVA) revealed a significant genetic distance between our Andalusian samples and other ones from the northern Iberian fringe (including Basque and Pyrenean populations). However, results from the multi-dimensional scaling analysis (MDS) yielded a well-defined group of Iberian populations separated from the other Mediterranean clusters observed. PMID:21664894

  19. Morphometric sexing of Northwest Atlantic Roseate Terns

    Science.gov (United States)

    Palestis, Brian G.; Nisbet, Ian C.T.; Hatch, Jeremy J.; Szczys, Patricia; Spendelow, Jeffrey A.

    2012-01-01

    A difficulty in the study of monomorphic species is the inability of observers to visually distinguish females from males. Based on a sample of 745 known-sex birds nesting at Bird Island, MA, USA, a discriminant function analysis (DFA) was used to sex Roseate Terns (Sterna dougallii) of the Northwest Atlantic population using morphological measurements. DFA using only the total length of the head (including the bill) correctly identified the sex of approximately 86% of the terns, which increased to 88% if both members of a pair were measured. Including additional measurements increased these percentages slightly, to 87% and 90%, respectively. These levels of accuracy are generally higher than those reported for other species of terns. Because female-female pairs are frequent in this population, one cannot assume that the member of a pair with the larger head is a male, and additional discriminant functions were developed to help separate female-female from male-female pairs.

  20. Characteristics and significance of ductile shear zone in Tianli, Jiangxi Province and Youxi, Zhejiang Province

    International Nuclear Information System (INIS)

    The result of experiment show that 40Ar/39Ar plateau age of muscovite which is from Tianli petrofabric in Guanfeng county, Jiangxi Province is 1019 +- 0.9 Ma, and 40Ar/39Ar plateau age of biotite which is from migmatite in Youxi petrofabric Jiangshan county, Zhejiang Province is 501.2 +- 2.2 Ma, and the heat event age is 127 Ma. The research shows that they are two larger scale ductile shear zones. The 40Ar/39Ar plateau ages represent respectively the forming time of Tianli ductile shear zone and Youxi ductile shear zone. According to the age data and regional geological investigation analysis, they belong separately to the part of two tectonic units of Yangtze and south China. It also shows that Jiang-Shao tectonic zone undergoes multiphase orogeny which are Jinning, Caledonian, Indosinian and Yanshanian epoch. It is of geological significance for re-understand again the crust evolution of south China