Sample records for cenozoic basaltic rocks

  1. Hainan mantle plume produced late Cenozoic basaltic rocks in Thailand, Southeast Asia. (United States)

    Yan, Quanshu; Shi, Xuefa; Metcalfe, Ian; Liu, Shengfa; Xu, Taoyu; Kornkanitnan, Narumol; Sirichaiseth, Thanyapat; Yuan, Long; Zhang, Ying; Zhang, Hui


    Intraplate volcanism initiated shortly after the cessation of Cenozoic seafloor spreading in the South China Sea (SCS) region, but the full extent of its influence on the Indochina block has not been well constrained. Here we present major and trace element data and Sr-Nd-Pb-Hf isotope ratios of late Cenozoic basaltic lavas from the Khorat plateau and some volcanic centers in the Paleozoic Sukhothai arc terrane in Thailand. These volcanic rocks are mainly trachybasalts and basaltic trachyandesites. Trace element patterns and Sr-Nd-Pb-Hf isotopic compositions show that these alkaline volcanic lavas exhibit oceanic island basalt (OIB)-like characteristics with enrichments in both large-ion lithophile elements (LILE) and high field strength elements (HFSEs). Their mantle source is a mixture between a depleted Indian MORB-type mantle and an enriched mantle type 2 (EMII). We suggest that the post-spreading intraplate volcanism in the SCS region was induced by a Hainan mantle plume which spread westwards to the Paleozoic Sukhothai arc terrane.

  2. Cenozoic volcanic rocks of Saudi Arabia (United States)

    Coleman, R.G.; Gregory, R.T.; Brown, G.F.


    The Cenozoic volcanic rocks of Saudi Arabia cover about 90,000 km2, one of the largest areas of alkali olivine basalt in the world. These volcanic rocks are in 13 separate fields near the eastern coast of the Red Sea and in the western Arabian Peninsula highlands from Syria southward to the Yemen Arab Republic.

  3. Geochemistry of ultramafic xenoliths in Cenozoic alkali basalts from ...

    Indian Academy of Sciences (India)

    5Department of Leisure Business Management, DeLin Institute of Technology, Taipei 236, Taiwan. ∗. Corresponding author. e-mail: Twelve ultramafic xenoliths in Cenozoic alkali basalts from Jiangsu province, eastern China have been analyzed for major, trace, Sr–Nd isotopic composition and ...

  4. From mantle roots to surface eruptions: Cenozoic and Mesozoic continental basaltic magmatism

    Czech Academy of Sciences Publication Activity Database

    Kämpf, H.; Németh, K.; Puziewicz, J.; Mrlina, Jan; Geissler, W.H.


    Roč. 104, č. 8 (2015), s. 1909-1912 ISSN 1437-3254 Institutional support: RVO:67985530 Keywords : continental basaltic volcanism * BASALT 2013 conference * Cenozoic * Mesozoic Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.133, year: 2015

  5. Geochemical constraints on the spatial distribution of recycled oceanic crust in the mantle source of late Cenozoic basalts, Vietnam (United States)

    Hoang, Thi Hong Anh; Choi, Sung Hi; Yu, Yongjae; Pham, Trung Hieu; Nguyen, Kim Hoang; Ryu, Jong-Sik


    This study presents a comprehensive analysis of the major and trace element, mineral, and Sr, Nd, Pb and Mg isotopic compositions of late Cenozoic intraplate basaltic rocks from central and southern Vietnam. The Sr, Nd, and Pb isotopic compositions of these basalts define a tight linear array between Indian mid-ocean-ridge basalt (MORB)-like mantle and enriched mantle type 2 (EM2) components. These basaltic rocks contain low concentrations of CaO (6.4-9.7 wt%) and have high Fe/Mn ratios (> 60) and FeO/CaO-3MgO/SiO2 values (> 0.54), similar to partial melts derived from pyroxenite/eclogite sources. This similarity is also supported by the composition of olivine within these samples, which contains low concentration of Ca and high concentrations of Ni, and shows high Fe/Mn ratios. The basaltic rocks have elevated Dy/Yb ratios that fall within the range of melts derived from garnet lherzolite material, although their Yb contents are much higher than those of modeled melts derived from only garnet lherzolite material and instead plot near the modeled composition of eclogite-derived melts. The Vietnamese basaltic rocks have lighter δ26Mg values (- 0.38 ± 0.06‰) than is expected for the normal mantle (- 0.25 ± 0.07‰), and these values decrease with decreasing Hf/Hf* and Ti/Ti* ratios, indicating that these basalts were derived from a source containing carbonate material. On primitive mantle-normalized multi-element variation diagrams, the central Vietnamese basalts are characterized by positive Sr, Eu, and Ba anomalies. These basalts also plot within the pelagic sediment field in Pbsbnd Pb isotopic space. This suggests that the mantle source of the basalts contained both garnet peridotite and recycled oceanic crust. A systematic analysis of variations in geochemical composition in basalts from southern to central Vietnam indicates that the recycled oceanic crust (possibly the paleo-Pacific slab) source material contains varying proportions of gabbro, basalt, and

  6. Geochemistry and petrology of pyroxenite xenoliths from Cenozoic alkaline basalts, Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Ackerman, Lukáš; Špaček, Petr; Medaris Jr., G.; Hegner, E.; Svojtka, Martin; Ulrych, Jaromír


    Roč. 57, č. 4 (2012), s. 199-219 ISSN 1802-6222 R&D Projects: GA ČR(CZ) GA205/09/1170 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z30120515 Institutional support: RVO:67985831 ; RVO:67985530 Keywords : pyroxenite * xenolith * Cenozoic * basalt * Sr-Nd isotopes * geothermobarometry Subject RIV: DD - Geochemistry Impact factor: 0.804, year: 2012

  7. [Comparison of fluorescence spectroscopy and plasma-mass spectrometry results of the Meso/Cenozoic basic rocks in SE China and its geo-implication]. (United States)

    Lou, Feng; Chen, Guo-Neng; Chen, Guo-Hui; Huang, Hai-Hua


    With comparison of the fluorescence spectroscopy and plasma-mass spectroscopy analysis results of the Meso/Cenozoic basic rocks of SE China, the authors found that the average SiO2 content of the Mesozoic basic rocks in this area is about 50%, while that of the Cenozoic basic rocks is about 43%. The former belongs to the basic group and the later to the ultrabasic group in igneous rock classification. Cenozoic basalts, accompanied with high magnesium content and low silica-alumina component, are obviously basic or ultrabasic rocks. Distinctive difference in the content of trace elements and of REE is also presented between the Mesozoic and the Cenozoic basic rocks. Distribution models of both trace elements and REE of the Mesozoic basic rocks are similar to those of the upper crust, and the models of the Cenozoic basic rocks are like those of OIB, indicating that basic rocks of the Cenozoic and OIB should originate from the mantle while that of the Mesozoic is from the bottom part of the upper crust with relationship to the evolution of the Mesozoic crustal magma layer of this area.

  8. Geochemical insights into the lithology of mantle sources for Cenozoic alkali basalts in West Qinling, China (United States)

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


    Although alkali basalts are common in oceanic islands and continental rifts, the lithology of their mantle sources is still controversial. While the peridotite is usually viewed as a common source lithology, there are increasing studies suggesting significant contributions from ultramafic metasomatites such as carbonated peridotite, pyroxenite and hornblendite to the origin of alkali basalts. The present study indicates that carbonated peridotite plus hornblendite would have served as the mantle sources of Cenozoic alkali basalts from the West Qinling orogen in China. The target basalts show low SiO2 contents of 36.9 to 40.8 wt% and highly variable Na2O + K2O contents from 0.86 to 4.77 wt%, but high CaO contents of 12.5 to 16.3 wt% and CaO/Al2O3 ratios of 1.42 to 2.19. They are highly enriched in the majority of incompatible trace elements, but depleted in Rb, K, Pb, Zr, Hf, and Ti. Furthermore, they exhibit high (La/Yb)N, Zr/Hf, Ce/Pb and Nb/Ta ratios, but low Ti/Eu and Hf/Sm ratios. Generally, with increasing (La/Yb)N and CaO/Al2O3 ratios, their Ti/Eu and Hf/Sm ratios decrease whereas their Zr/Hf, Ce/Pb and Nb/Ta ratios increase. These major and trace element features are similar to those of carbonatites and hornblendite-derived melts to some extent, but significantly different from those of mid-ocean ridge basalts (MORB). This suggests that the alkali basalts would be originated from metasomatic mantle sources. A comparison of the major-trace elements in the alkali basalts with those of some representative mantle-derived melts indicates that the source lithology of alkali basalts is a kind of ultramafic metasomatites that are composed of carbonated peridotite and hornblendite. Such metasomatites would be generated by reaction of the depleted MORB mantle peridotite with hydrous, carbonate-bearing felsic melts derived from partial melting of the subducted Paleotethyan oceanic crust. Therefore, the melt-peridotite reaction at the slab-mantle interface in the

  9. Tachylyte in Cenozoic basaltic lavas from the Czech Republic and Iceland: contrasting compositional trends (United States)

    Ulrych, Jaromír; Krmíček, Lukáš; Teschner, Claudia; Řanda, Zdeněk; Skála, Roman; Jonášová, Šárka; Fediuk, Ferry; Adamovič, Jiří; Pokorný, Richard


    Tachylytes from rift-related volcanic rocks were recognized as: (i) irregular veinlets in host alkaline lava flows of the Kozákov volcano, Czech Republic, (ii) (sub)angular xenoliths in alkaline lava of the feeding channel of the Bukovec volcano, Czech Republic, and (iii) paleosurface of a tholeiitic lava flow from Hafrafell, Iceland. The tachylyte from Kozákov is phonotephrite to tephriphonolite in composition while that from Bukovec corresponds to trachyandesite to tephriphonolite. Both glass and host rock from Hafrafell are of tholeiitic basalt composition. The tachylyte from Kozákov, compared with the host rock, revealed a substantial enrichment in major elements such as Si, Al and alkalis along with Rb, Sr, Ba, Nb, Zr, REE, Th and U. The tachylyte from Bukovec displays contrasting trends in the incompatible element contents. The similarity in composition of the Hafrafell tachylyte paleosurface layer and parental tholeiitic basalt is characteristic for lavas. The host/parent rocks and tachylytes have similar initial Sr-Nd characteristics testifying for their co-magmatic sources. The initial ɛNd values of host/parent rocks and tachylytes from the Bohemian Massif (+3.4 to +3.9) and those from Iceland (+6.3) are interpreted as primary magma values. Only the tachylyte from Bukovec shows a different ɛNd value of -2.1, corresponding to a xenolith of primarily sedimentary/metamorphic origin. The tachylyte from Kozákov is a product of an additional late magmatic portion of fluids penetrating through an irregular fissure system of basaltic lava. The Bukovec tachylyte is represented by xenoliths originated during the interaction of ascending basaltic melt with granitoids or orthogneisses, whereas the Hafrafell tachylyte is a product of a rapid cooling on the surface of a basalt flow.

  10. Geochemistry of sulfur isotopes in basaltic rocks

    International Nuclear Information System (INIS)

    Hubberten, H.W.; Puchelt, H.


    Sulfur isotope ratios in oceanic basalts from three different localities (Bermuda Triangle, East Pacific Rise, and Galapagos Spreading Centre and in terrestrial basalts from Saudi Arabia have been analyzed by mass spectroscopy. In order to recognize and to interpret, if possible, secondary isotopic changes of basalts, various sulfurous materials occurring together with basalts gypsum, deep thermal pyrites) have been investigated too. By mechanochemical sample preparation it was possible to determine various sulfur carriers separately. Sulfides occurring as droplets in basalts showed values of -0.4 to -0.8 0 / 00 in materials from Bermuda Triangle, Galapagos Spreading Centre, and Saudi Arabia. The values are in agreement with those suggested for primary sulfur in the earth mantle. The basalts of East Pacific Rise show a significant 34 S enrichment with a mean value of +3 0 / 00 , which may be caused by processes in the course of magmatic differentiation. Because of secondary effects sulfate sulfur, including secondary pyrite, varies considerably in its sulfur isotope ratio (delta values between -12 to +22 0 / 00 ). Samples without recognizable secondary effects have delta values of about +1.5 0 / 00 , which can be supposed for primary sulfates. Mechanically separated pyrites from deep thermal superimposed basalts show slightly negative 34 S values

  11. Geochemical characteristics of the high- and low-Ti basaltic rocks from the uplifted shoulder of the Ohře (Eger) Rift, Western Bohemia

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Jelínek, E.; Řanda, Zdeněk; Lloyd, F. E.; Balogh, K.; Hegner, E.; Novák, Jiří Karel


    Roč. 70, č. 4 (2010), s. 319-333 ISSN 0009-2819 R&D Projects: GA AV ČR IAA300130706 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10480505 Keywords : Bohemian Massif * Ohře Rift * Eger Rift * Krušné hory Mts. * Erzgebirge * Cenozoic volcanism * high-Ti basaltic rocks * geochemistry Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.525, year: 2010

  12. Mesozoic and cenozoic volcanic rocks from central and southern Tibet: 39Ar-40Ar dating, petrological characteristics and geodynamical significance

    International Nuclear Information System (INIS)

    Coulon, C.; Bollinger, C.; Wang, S.


    Field relations, radiometric ages and mineralogical and chemical characteristics of the orogenic volcanic rocks from the Lhasa block (Tibet) are studied. Volcanic activity started before the deposition of the Albian-Aptian sedimentary units (Takena Formation and Xigaze Group). Volcanism is volumetrically limited in the northern part of the Lhasa block: basalts, andesites and dacites are present while ignimbrites are scarce. Radiometric ages of these rocks range between 110 and 80 Ma. Conversely, in the southern part of the Lhasa block, volcanism is largely developed (Gangdese belt). There, paroxysmal activity occurred later than in the north, between 60 and 50 Ma (Lingzizong Formation). This volcanism is mainly represented by andesites and ignimbrites. A younger episode at about 15-10 Ma took place in this southern region. The mineralogical and geochemical characteristics indicate that, as a whole, the volcanic rocks from the Lhasa block belong to a calc-alkaline continental-margin series, enriched in K 2 O and other incompatible elements. Subordinate potassic alkaline lavas are present in the northern margin of the Gangdese belt; some basalts exhibit a tholeiitic affinity (Daquin area, southern region). The geodynamic significance of these Cenozoic volcanic rocks lies in the relative motion of India and the Lhasa block, after accretion of the latter to the northern Qantang block. A geodynamic model based on changes of the type of subduction of the Indian oceanic crust beneath the Lhasa block, for the period 120-40 Ma, is proposed to account for the abundance, age, and magmatic affinity of the volcanic products. (orig.)

  13. Equilibration of Leachants with Basalt Rock for Repository Simulation Tests

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C.M.


    In a nuclear waste repository in basalt, the groundwater will have a low redox potential (Eh) which may affect the leach rate of SRP waste glass. Accurate laboratory simulations of conditions in a basalt reposition must maintain low Eh values throughout the course of the experiment. In this report, important parameters affecting the ability of basalt to maintain appropriate Eh-pH conditions are examined, in particular basalt type and groundwater simulation.

  14. Tachylyte in Cenozoic basaltic lavas from the Czech Republic and Iceland: contrasting compositional trends

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Krmíček, Lukáš; Teschner, C.; Řanda, Zdeněk; Skála, Roman; Jonášová, Šárka; Fediuk, F.; Adamovič, Jiří; Pokorný, R.


    Roč. 111, č. 5 (2017), s. 761-775 ISSN 0930-0708 Institutional support: RVO:67985831 ; RVO:61389005 Keywords : basaltic glass * chemical composition * major genetic types * mineral composition * rift-related volcanites * Sr-Nd isotopes Subject RIV: DB - Geology ; Mineralogy; CB - Analytical Chemistry, Separation (UJF-V) OBOR OECD: Mineralogy; Analytical chemistry (UJF-V) Impact factor: 1.236, year: 2016

  15. Basalt Related to Lunar Mg-Suite Plutonic Rocks: A Fragment in Lunar Meteorite ALH 81005 (United States)

    Treiman, A. H.; Gross, J.


    We report on a basalt clast, in meteorite ALH 81005, which appears to be from a volcanic equivalent of an Mg-suite plutonic rock. Its mineral compositions, mineral proportions, and trace minerals are like those of Mg-norites.

  16. Basaltic rocks behavior of the Corrientes and Entre Rios province from the alcali silice reaction

    International Nuclear Information System (INIS)

    Marfil, S.; Batic, O.; Grecco, L.; Falcone, D.


    This work is about the basaltic rocks deposits in Mesopotamia - Argentina. This material is used for dikes, flooring and art . In several of them has been developed expansive processes associated with alkali - silica reaction such as pavements of some routes. In order to evaluate the behavior of these rocks their are obtained samples from the quarries using standard methods such as petrographic, rod accelerated and dissolved silica agree with the IRA M standards

  17. Technical support for GEIS: radioactive waste isolation in geologic formations. Volume 7. Baseline rock properties-basalt

    Energy Technology Data Exchange (ETDEWEB)


    This volume, Y/OWI/TM-36/7 Baseline Rock Properties--Basalt, is one of a 23-volume series, ''Technical Support for GEIS: Radioactive Waste Isolation in Geologic Formations, Y/OWI/TM-36'' which supplements a ''Contribution to Draft Generic Environmental Impact Statement on Commercial Waste Management: Radioactive Waste Isolation in Geologic Formations, Y/OWI/TM-44.'' The series provides a more complete technical basis for the preconceptual designs, resource requirements, and environmental source terms associated with isolating commercial LWR wastes in underground repositories in salt, granite, shale and basalt. Wastes are considered from three fuel cycles: uranium and plutonium recycling, no recycling of spent fuel and uranium-only recycling. This report contains an evaluation of the results of a literature survey to define the rock mass properties of a generic basalt, which could be considered as a geological medium for storing radioactive waste. The general formation and structure of basaltic rocks is described. This is followed by specific descriptions and rock property data for the Dresser Basalt, the Amchitka Island Basalt, the Nevada Test Site Basalt and the Columbia River Group Basalt. Engineering judgment has been used to derive the rock mass properties of a typical basalt from the relevant intact rock property data and the geological information pertaining to structural defects, such as joints and faults.

  18. Geochemistry and petrogenesis of basaltic rocks from the Develidağ volcanic complex, Central Anatolia, Turkey (United States)

    Kürkcüoglu, Biltan


    The Develidağ volcanic zone (DVZ) is a part of the Middle Miocene-Quaternary Cappadocian Volcanic Province (CVP) in central Anatolia. The DVZ is located at the eastern side of the Plio-Quaternary Sultansazlığı pull-apart basin, that opened along the Ecemiş left-lateral strike-slip fault. Towards the south, the volcanic rocks of the DVZ overlie the Paleozoic metamorphic rocks of the Taurus range. Regional stratigraphic studies indicate that volcanic rocks of the DVZ crop out in a ˜N-S trending rectangular-shaped exposure in the middle of which Middle Miocene andesitic rocks are found surrounded by Upper Miocene basaltic rocks. The purpose of this paper is to present basic geochemical data for the DVZ rocks and discuss possible processes of magma generation. The Develidağ basalts are characterized by low LILE (Rb, K, Ba, Th) and high HFSE (Nb,Zr,Hf,Y) contents, whereas the andesites generally have high LILE and HFSE values except for Nb and Zr. Variable abundances of Pb (3.11-12.09 ppm) and U (0.36-2.64 ppm) are associated with high Ba content within the rock suites. Although low Nb/La (0.6-0.7) and relatively high Ba/Nb ratios indicate crustal involvement for the basalts, high Zr/Ba (0.5), Zr/Hf (42-47) and Th/U (3.13-4.69) values imply contributions from an asthenospheric source component. Furthermore, the high Zr/Hf values (>36) are the diagnostic feature of metasomatized mantle (Dupuy et al., 1992; Rudnick et al., 1993). Moreover, multi-element patterns show that Develidağ basalts have similar trace element signatures to those of the US Cascades tholeiites. The ratios of Zr/Hf, Zr/Ba, Nb/Th and Sr/Ce indicate that basaltic rocks are derived from a MORB-like mantle, and calculated melting model reflects generation from a spinel peridotite source (3-4% melting), but the combined effects of melting and assimilation and fractional crystallization (AFC) processes seem to be partially responsible for the relatively evolved rocks. Typical tholeiitic

  19. Geochemistry and petrology of basaltic rocks from the Marshall Islands (United States)

    Davis, Alice S.; Schwab, William C.; Haggerty, Janet A.


    A variety of volcanic rock was recovered from the flanks of seamounts, guyots, atolls, and islands in the Ratak chain of the Marshall Islands on the U.S. Geological Survey cruise L9-84-CP. The main objective of this cruise was to study the distribution and composition of ferromanganese oxide crusts. Preliminary results of managanese crust composition are reported by Schwab et al. (1985) and detailed studies are in preparation (Schwab et al., 1986). A total of seven seafloor edifices were studied using 12 khz, 3.5 khz and air gun seismic reflection, chain dredge and box corer. Bathymetry and ship track lines are presented by Schwab and Bailey (1985). Of the seven edifices surveyed two support atolls (Majuro and Taongi) and one is a tiny island (Jemo). Dredge locations and water depths are given in Table 1 and dredge locations are shown in Figure 1. Due to equipment failures depths of dredge hauls were limited to shallow depth for all except the first two sites occupied. Recovery consisted mostly of young, poorly-consolidated limestone of fore-reef slope deposit and minor volcanogenic breccia and loose talus. The breccia and pieces of talus are thickly encrusted with ferromanganese oxide, whereas the young limestone is only coated by a thin layer. Four of the seven sites surveyed yielded volcanic rock. The volcanic rock, volumetrically a minor part of each dredge haul, consists mostly of lapilli and cobble-size clasts in a calcareous matrix or as loose talus. Most clasts show evidence of reworking, being sub- to well rounded, sometimes with a thin ferromanganese crust of their own. This paper reports preliminary findings on the petrology and geochemistry of volcanic rock recovered.

  20. The human impact on natural rock reserves using basalt, anorthosite, and carbonates as raw materials in insulation products

    DEFF Research Database (Denmark)

    Dahl, Tais Wittchen; Clausen, Anders U.; Hansen, Peter B.


    , and carbonates are widespread on all continents. Although basaltic rocks cover most of the ocean floor, these reserves are hidden below several kilometres of water and therefore are regarded as inaccessible. Instead, large igneous provinces on land constitute major basaltic reserves useful for human rock...... of these rock types are so large that they could supply current human demand for millions of years. The natural degradation of surface rocks occurs by physical and chemical weathering creating sediment that is transported along rivers and deposited in the ocean. Sediments are either obducted with continental......% basalt, 20 wt% anorthosite, and 40 wt% cement-bonded renewable materials. This study provides an overview of the natural cycle of these resources, including their abundances in nature, and sets the consumption by the stone wool industry and other human activities in perspective. Basalt, anorthosite...

  1. First data on Sm-Nd ages of Archean basalts of the Karelian granite-green rock region

    International Nuclear Information System (INIS)

    Sochevanov, N.N.; Arestov, N.A.; Matrenichev, V.A.; Lobach-Zhuchenko, S.B.; Guseva, V.F.


    The first results of Sm-Nd dating of metabasalts of two green-rock structures located in the South-East part of the Baltic shield are presented. The age of formation of basalt mass and differentiated mass was 2916±70 and 2960±150 Ma, respectively. Reliable determination of basalt vulcanism manifestation time (2.9 Ga) permits evaluating the lower boundary of formation of granite-green rock complex as 3.0±0.1 Ga

  2. Metal transports and enrichments in iron depositions hosted in basaltic rocks. II: Metal rich fluids and Fe origin (United States)

    Zhang, Ronghua; Zhang, Xuetong; Hu, Shumin


    This study focuses on revealing the mechanism of metal transport, enrichment and Fe origin of iron deposition during water basalt interactions occurred in basaltic rocks. Observations of the iron deposits (anhydrite-magnetite-pyroxene type deposits) hosted in K-rich basaltic rocks in the Mesozoic volcanic area of the Middle-Lower Yangtze River valley, China, indicate that the mechanism of metal transport and enrichment for those deposits are significant objective to scientists, and the Fe origin problem is not well resolved. Here the metal transport, enrichment and iron origin have been investigated in high temperature experiments of water basaltic interactions. These deposits were accompanying a wide zone with metal alteration. The effects of hydrothermal alteration on major rock-forming element concentrations in basaltic rock were investigated by systematically comparing the chemical compositions of altered rocks with those of fresh rocks. In the deposits, these metals are distributed throughout altered rocks that exhibit vertical zoning from the deeper to the shallow. Then, combined with the investigations of the metal-alterations, we performed kinetic experiments of water-basaltic rock interactions using flow-through reactors in open systems at temperatures from 20 °C to 550 °C, 23-34 MPa. Release rates for the rock-forming elements from the rocks have been measured. Experiments provide the release rates for various elements at a large temperature range, and indicate that the dissolution rates (release rates) for various elements vary with temperature. Si, Al, and K have high release rates at temperatures from 300 °C to 500 °C; the maximum release rates (RMX) for Si are reached at temperatures from 300 °C to 400 °C. The RMXs for Ca, Mg, and Fe are at low temperatures from 20 °C to 300 °C. Results demonstrate that Fe is not released from 400 °C to 550 °C, and indicate that when deep circling fluids passed through basaltic rocks, Fe was not mobile, and

  3. The effect of rock composition on cyanobacterial weathering of crystalline basalt and rhyolite. (United States)

    Olsson-Francis, K; Simpson, A E; Wolff-Boenisch, D; Cockell, C S


    The weathering of volcanic rocks contributes significantly to the global silicate weathering budget, effecting carbon dioxide drawdown and long-term climate control. The rate of chemical weathering is influenced by the composition of the rock. Rock-dwelling micro-organisms are known to play a role in changing the rate of weathering reactions; however, the influence of rock composition on bio-weathering is unknown. Cyanobacteria are known to be a ubiquitous surface taxon in volcanic rocks. In this study, we used a selection of fast and slow growing cyanobacterial species to compare microbial-mediated weathering of bulk crystalline rocks of basaltic and rhyolitic composition, under batch conditions. Cyanobacterial growth caused an increase in the pH of the medium and an acceleration of rock dissolution compared to the abiotic controls. For example, Anabaena cylindrica increased the linear release rate (R(i)(l)) of Ca, Mg, Si and K from the basalt by more than fivefold (5.21-12.48) and increased the pH of the medium by 1.9 units. Although A. cylindrica enhanced rhyolite weathering, the increase in R(i)(l) was less than threefold (2.04-2.97) and the pH increase was only 0.83 units. The R(i)(l) values obtained with A. cylindrica were at least ninefold greater with the basalt than the rhyolite, whereas in the abiotic controls, the difference was less than fivefold. Factors accounting for the slower rate of rhyolite weathering and lower biomass achieved are likely to include the higher content of quartz, which has a low rate of weathering and lower concentrations of bio-essential elements, such as, Ca, Fe and Mg, which are known to be important in controlling cyanobacterial growth. We show that at conditions where weathering is favoured, biota can enhance the difference between low and high Si-rock weathering. Our data show that cyanobacteria can play a significant role in enhancing rock weathering and likely have done since they evolved on the early Earth. © 2012

  4. Assessment of the rock burst potential in basalt at the Hanford Site

    International Nuclear Information System (INIS)

    Blake, W.


    The phenomenon of rock bursting has been reviewed and specific case histories have been presented, along with the measures most commonly taken to minimize their occurrence and effects. A combination of high stresses and brittle rock types is necessary to initiate bursting but is not sufficient to do so unless other parameters are present (i.e. an extensive mined-out area, a high extraction ratio, and geologic structures, or discontinuities). Since none of these parameters will result from the construction of a deep underground nuclear waste repository in basalt at the Hanford Site in Southeastern Washington, rock bursting should not occur either during or after this construction. 75 refs., 35 figs., 2 tabs

  5. Compositional diversity of Late Cenozoic basalts in a transect across the southern Washington Cascades: Implications for subduction zone magmatism (United States)

    Leeman, William P.; Smith, Diane R.; Hildreth, Wes; Palacz, Zen; Rogers, Nick


    Major volcanoes of the Southern Washington Cascades (SWC) include the large Quaternary stratovolcanoes of Mount St. Helens (MSH) and Mount Adams (MA) and the Indian Heaven (IH) and Simcoe Mountain (SIM) volcanic fields. There are significant differences among these volcanic centers in terms of their composition and evolutionary history. The stratovolcanoes consist largely of andesitic to dacitic lavas and pyroclastics with minor basalt flows. IH consists dominantly of basaltic with minor andesite lavas, all erupted from monogenetic rift and cinder cone vents. SIM has a poorly exposed andesite to rhyolite core but mainly consists of basaltic lavas erupted from numerous widely dispersed vents; it has the morphology of a shield volcano. Distribution of mafic lavas across the SWC is related to north-northwest trending faults and fissure zones that indicate a significant component of east-west extension within the area. There is overlap in eruptive history for the areas studied, but it appears that peak activity was progressively older (MSH (slab-metasomatized subarc mantle. The juxtaposition of such different mantle domains within the lithospheric mantle is viewed as a consequence of (1) tectonic mixing associated with accretion of oceanic and island arc terranes along the Pacific margin of North America prior to Neogene time, and possibly (2) a seaward jump in the locus of subduction at about 40 Ma. The Cascades arc is unusual in that the subducting oceanic plate is very young and hot. We suggest that slab dehydration outboard of the volcanic front resulted in a diminished role of aqueous fluids in generating or subsequently modifying SWC magmas compared to the situation at most convergent margins. Furthermore, with low fluid flux conditions, basalt generation is presumably triggered by other processes that increase the temperature of the mantle wedge (e.g., convective mantle flow, shear heating, etc.).

  6. Review of and contribution to the Stratigraphy of the Cenozoic Igneous Rocks in the Republic of Yemen

    International Nuclear Information System (INIS)

    El-Nakhal, H.A.


    In Yemen the Cenozoic igneous rocks consists of intrusive and extrusive rocks with interlayered sediments, all of which are included within the Manakha Group (latest Cretaceous-Holocene). This group is subdivided into the Haraz Formation which includes the latest Cretaceous-Tertiary volcanics and the interlayered sediments, the Aden Formation which includes the Late Tertiary-Holocene volcanics, and the Bura Formations are introduced here as new units. The Haraz Formation replaces the informal names: Trap Series, Yemen Volcanics and Aden Trap Series, Yemen Volcanics and Adan Trap Series.The Adan Formation are a readaptation of the term Aden Vocanic Series. A startotype for the Aden Formation is designated in the Shuqra-Ahwar area. (author)

  7. New chemical determinations of zinc in basalts, and rocks of similar composition (United States)

    Rader, L.F.; Swadley, W.C.; Huffman, C.; Lipp, H.H.


    New determinations of zinc in 124 basalts by the chemical method described (Huff-Man et al. 1963) are reported. Average zinc values, in per cent, for basalts from diverse regions are as follows: Idaho, 28 samples, 0.013; Hawaii, 33 samples, 0.010; Connecticut, 27 samples, 0.0090; Oregon, 17 samples, 0.0081; California, 8 samples, 0.0071; and New Mexico, 11 samples, 0.0086; average, all samples, 0.0099 per cent zinc. A plot of differentiation indicator ratios calculated from the conventional rock analyses, CaO/(Na2O + K2O) as the ordinate and SiO2/MgO as the abscissa, was used to select, from different localities, samples essentially the same in chemical composition that were to be used for comparisons of zinc and other minor elements. Zinc correlates with MnO and with total iron as FeO. An inverse relationship found for zinc and manganese is related to the total iron content of the basalts. Thus for a given iron concentration as zinc increases, manganese decreases and vice versa. Ratios of zinc, the common denominator, to 11 other minor elements determined spectro-graphically show correlations with cobalt, gallium, scandium, yttrium, and zirconium. ?? 1963.

  8. Mineral storage of CO2/H2S gas mixture injection in basaltic rocks (United States)

    Clark, D. E.; Gunnarsson, I.; Aradottir, E. S.; Oelkers, E. H.; Sigfússon, B.; Snæbjörnsdottír, S. Ó.; Matter, J. M.; Stute, M.; Júlíusson, B. M.; Gíslason, S. R.


    Carbon capture and storage is one solution to reducing CO2 emissions in the atmosphere. The long-term geological storage of buoyant supercritical CO2 requires high integrity cap rock. Some of the risk associated with CO2 buoyancy can be overcome by dissolving CO2 into water during its injection, thus eliminating its buoyancy. This enables injection into fractured rocks, such as basaltic rocks along oceanic ridges and on continents. Basaltic rocks are rich in divalent cations, Ca2+, Mg2+ and Fe2+, which react with CO2 dissolved in water to form stable carbonate minerals. This possibility has been successfully tested as a part of the CarbFix CO2storage pilot project at the Hellisheiði geothermal power plant in Iceland, where they have shown mineralization occurs in less than two years [1, 2]. Reykjavik Energy and the CarbFix group has been injecting a mixture of CO2 and H2S at 750 m depth and 240-250°C since June 2014; by 1 January 2016, 6290 tons of CO2 and 3530 tons of H2S had been injected. Once in the geothermal reservoir, the heat exchange and sufficient dissolution of the host rock neutralizes the gas-charged water and saturates the formation water respecting carbonate and sulfur minerals. A thermally stable inert tracer was also mixed into the stream to monitor the subsurface transport and to assess the degree of subsurface carbonation and sulfide precipitation [3]. Water and gas samples have been continuously collected from three monitoring wells and geochemically analyzed. Based on the results, mineral saturation stages have been defined. These results and tracer mass balance calculations are used to evaluate the rate and magnitude of CO2 and H2S mineralization in the subsurface, with indications that mineralization of carbon and sulfur occurs within months. [1] Gunnsarsson, I., et al. (2017). Rapid and cost-effective capture and subsurface mineral storage of carbon and sulfur. Manuscript submitted for publication. [2] Matter, J., et al. (2016). Rapid

  9. Chemical trends in the Ice Springs basalt, Black Rock Desert, Utah

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, W.C.; Nash, W.P.


    The Holocene Ice Springs volcanic field of west-central Utah consists of 0.53 km/sup 3/ of tholeiitic basalts erupted as a sequence of nested cinder cones and associated lava flows. Whole rock x-ray fluorescence and atomic absorption analysis of ninety-six samples of known relative age document statistically significant inter- and intra-eruption chemical variations. Elemental trends include increases in Ti, Fe, Ca, P, and Sr and decreases in Si, K, Rb, Ni, Cr, and Zr with decreasing age. Microprobe analyses of microphenocrysts of olivine, plagioclase, and Fe-Ti oxides and of groundmass olivine, plagioclase, and clinopyroxene indicate limited chemical variation between mineral assemblages of the eruptive events. Petrographic analyses have identified the presence of minor amounts of silicic xenoliths, orthopyroxene megacrysts, and plagioclase xenocrysts. Potassium-argon determinations establish the existence of excess argon in the basaltic cinder (30.05 x 10/sup -12/ moles/gm) and in distal lava flows (8.29 x 10/sup -12/ moles/gm) which suggest apparent ages of 16 and 4.3 million years respectively. Strontium isotopic data (Puskar and Condie, 1973) show systematic variations from oldest eruptions (87Sr/86Sr=0.7052) to youngest eruptions (87Sr/86Sr=0.7059).

  10. Source implications for the different geochemical features of recent basaltic rocks from the northernmost part of the Cappadocian region, Turkey (United States)

    Kurkcuoglu, Biltan; Yurur, Tekin


    Extensive magmatic activities developed since middle-Miocene, in the Cappadocian Region of Central Anatolia in Turkey. The nature and the sources of the magmatism were well-constrained by previous studies. Even though the sources of Strato-volcanoes and monogenetic vents were briefly explained, extremely young basalts (1.22 - 0.094 Ka) situated in northernmost part of Cappadocian Region and erupted between the two extentional faults, are not deeply investigated. Karaburna and Gülşehir lavas (1.22, 0.094 Ka, respectively, Dogan, 2011) are considered as a part of the Central Anatolian Volcanic Province, with extremely young ages, generated either at the final or after the final stage of the Cappadocian systems. These lavas have similar LIL and HFS elements patterns with each other, however, Karaburna samples are more enriched in HFS elements. These basalts also display approximately similar trends in LIL elements ( except Rb) and reflect HFS depletion relative to the OIB signature, moreover, HFS are more enriched compared to the Hasandag basaltic rocks, all these features suggesting, basaltic rocks are originated from the modified mantle source. Karaburna and Gülşehir basalts have low Nb/La (0.45-0.5 ; 0.35-0.42), Nb/Y( 0.33-.39; 0.27-0.44 Nb/Th (2.75-4.6; 1.26-1.68) and high Ba/Nb (22-32; 38-43) ratios suggesting the contributions from the crustal sources, moreoever, Gülşehir basaltic rocks differ from the Karaburna lavas with relatively low Nb/U ( 4.5-6.4) and high Ba/La ( 14.67-17.20) Th/La (0.22-0.27), whereas Karaburna samples are represented by low Ba/La (10.04-14.90) and Th/La (0.09-0.16) ratios, these geochemical features reveal that these differences are originated either from the different degrees of crustal involvement or change in the nature of the source in a short time interval. Of all the most recent basaltic products generated in central Anatolia are alkaline in nature, besides, the trace element content, multi-element patterns and HFS/LIL and

  11. Cenozoic mantle composition evolution of southern Tibet indicated by Paleocene ( 64 Ma) pseudoleucite phonolitic rocks in central Lhasa terrane (United States)

    Qi, Yue; Gou, Guo-Ning; Wang, Qiang; Wyman, Derek A.; Jiang, Zi-Qi; Li, Qiu-Li; Zhang, Le


    The question of whether continental subduction processes in collisional orogenic belts can trigger wide-spread mantle metesomatism and crustal material recycling remains unresolved. Miocene (25-8 Ma) ultrapotassic rocks in southern Tibet are the only mantle-derived magmatic rocks emplaced after the collision between India and Asia and they have been linked to the onset of east-west extensional stresses as the surface uplift of the Tibetan Plateau reached near-maximum elevation. However, their petrogenesis remains highly controversial, particularly the issue of whether their extremely enriched Sr-Nd isotopic characteristics were related to metasomatism derived from subducted Indian continental materials during the Cenozoic. Here we report on a Paleocene silicate-unsaturated, pseudoleucite phonolitic dike, in the Rongniduo area of central Lhasa terrane. In-situ SIMS (secondary ion mass spectrometry) apatite U-Pb age indicates the dike was generated at 64.1 ± 4.2 Ma, which slightly predates the age of initial India and Asia collision (about 55-50 Ma). This is the oldest age yet reported for ultrapotassic rocks in southern Tibet. Samples from this dike have distinctly more depleted Sr-Nd (whole rock: (87Sr/86Sr)i = 0.7064 to 0.7062, εNd(t) = - 1.5 to 0.4; in situ apitite: (87Sr/86Sr)i = 0.7059 to 0.7060, εNd(t) = - 2.0 to 0.4) isotopic compositions, than those of Miocene (25-8 Ma) ultrapotassic rocks in the central Lhasa terrane ((87Sr/86Sr)i = 0.7106 to 0.7399, εNd(t) = - 10.6 to - 18.5). Our new data provides important constraints on pre-collisional mantle characteristics beneath the Lhasa terrane. We suggest that these 64 Ma pseudoleucite phonolitic rocks were derived from the enriched lithospheric mantle metasomatized by subducted Tethyan oceanic materials in response to Neo-Tethyan slab roll-back. As a consequence, the younger Miocene ultrapotassic rocks, which display different geochemical compositions from the pre-collisional ultrapotassic rocks, were most

  12. Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria-Europe plate boundary (Western Alps, Calabria, Corsica) (United States)

    Malusà, Marco G.; Faccenna, Claudio; Baldwin, Suzanne L.; Fitzgerald, Paul G.; Rossetti, Federico; Balestrieri, Maria Laura; Danišík, Martin; Ellero, Alessandro; Ottria, Giuseppe; Piromallo, Claudia


    Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary.

  13. Mineralization of Bacteria in Terrestrial Basaltic Rocks: Comparison With Possible Biogenic Features in Martian Meteorite Allan Hills 84001 (United States)

    Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Gibson, E. K., Jr.; Romanek, C. S.


    The identification of biogenic features altered by diagenesis or mineralization is important in determining whether specific features in terrestrial rocks and in meteorites may have a biogenic origin. Unfortunately, few studies have addressed the formation of biogenic features in igneous rocks, which may be important to these phenomena, including the controversy over possible biogenic features in basaltic martian meteorite ALH84001. To explore the presence of biogenic features in igneous rocks, we examined microcosms growing in basaltic small-scale experimental growth chambers or microcosms. Microbial communities were harvested from aquifers of the Columbia River Basalt (CRB) group and grown in a microcosm containing unweathered basalt chips and groundwater (technique described in. These microcosms simulated natural growth conditions in the deep subsurface of the CRB, which should be a good terrestrial analog for any putative martian subsurface ecosystem that may have once included ALH84001. Here we present new size measurements and photomicrographs comparing the putative martian fossils to biogenic material in the CRB microcosms. The range of size and shapes of the biogenic features on the CRB microcosm chips overlaps with and is similar to those on ALH84001 chips. Although this present work does not provide evidence for the biogenicity of ALH84001 features, we believe that, based on criteria of size, shape, and general morphology, a biogenic interpretation for the ALH84001 features remains plausible.

  14. Radiocarbon as a Reactive Tracer for Tracking Permanent CO2 Storage in Basaltic Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Matter, Juerg [Columbia Univ., New York, NY (United States); Stute, Martin [Columbia Univ., New York, NY (United States); Schlosser, Peter [Columbia Univ., New York, NY (United States); Broecker, Wallace [Columbia Univ., New York, NY (United States)


    In view of concerns about the long-term integrity and containment of CO2 storage in geologic reservoirs, many efforts have been made to improve the monitoring, verification and accounting methods for geologically stored CO2. Our project aimed to demonstrate that carbon-14 (14C) could be used as a reactive tracer to monitor geochemical reactions and evaluate the extent of mineral trapping of CO2 in basaltic rocks. The capacity of a storage reservoir for mineral trapping of CO2 is largely a function of host rock composition. Mineral carbonation involves combining CO2 with divalent cations including Ca2+, Mg2+ and Fe2+. The most abundant geological sources for these cations are basaltic rocks. Based on initial storage capacity estimates, we know that basalts have the necessary capacity to store million to billion tons of CO2 via in situ mineral carbonation. However, little is known about CO2-fluid-rock reactions occurring in a basaltic storage reservoir during and post-CO2 injection. None of the common monitoring and verification techniques have been able to provide a surveying tool for mineral trapping. The most direct method for quantitative monitoring and accounting involves the tagging of the injected CO2 with 14C because 14C is not present in deep geologic reservoirs prior to injection. Accordingly, we conducted two CO2 injection tests at the CarbFix pilot injection site in Iceland to study the feasibility of 14C as a reactive tracer for monitoring CO2-fluid-rock reactions and CO2 mineralization. Our newly developed monitoring techniques, using 14C as a reactive tracer, have been successfully demonstrated. For the first time, permanent and safe disposal of CO2 as environmentally benign carbonate minerals in basaltic rocks could be shown. Over 95% of the injected CO2 at the Carb

  15. Dust coatings on basaltic rocks and implications for thermal infrared spectroscopy of Mars (United States)

    Johnson, J. R.; Christensen, P.R.; Lucey, P.G.


    Thin coatings of atmospherically deposited dust can mask the spectral characteristics of underlying surfaces on Mars from the visible to thermal infrared wavelengths, making identification of substrate and coating mineralogy difficult from lander and orbiter spectrometer data. To study the spectral effects of dust coatings, we acquired thermal emission and hemispherical reflectance spectra (5-25 μm; 2000-400 cm-1) of basaltic andesite coated with different thicknesses of air fall-deposited palagonitic soils, fine-grained ceramic clay powders, and terrestrial loess. The results show that thin coatings (10-20 μm) reduce the spectral contrast of the rock substrate substantially, consistent with previous work. This contrast reduction continues linearly with increasing coating thickness until a "saturation thickness" is reached, after which little further change is observed. The saturation thickness of the spectrally flat palagonite coatings is ~100-120 μm, whereas that for coatings with higher spectral contrast is only ~50-75 μm. Spectral differences among coated and uncoated samples correlate with measured coating thicknesses in a quadratic manner, whereas correlations with estimated surface area coverage are better fit by linear functions. Linear mixture modeling of coated samples using the rock substrate and coating materials as end-members is also consistent with their measured coating thicknesses and areal coverage. A comparison of ratios of Thermal Emission Spectrometer (TES) spectra of dark and bright intracrater and windstreak deposits associated with Radau crater suggests that the dark windstreak material may be coated with as much as 90% areal coverage of palagonitic dust. The data presented here also will help improve interpretations of upcoming mini-TES and Thermal Emission Imaging System (THEMIS) observations of coated Mars surface materials.

  16. Plume-stagnant slab-lithosphere interactions: Origin of the late Cenozoic intra-plate basalts on the East Eurasia margin (United States)

    Kimura, Jun-Ichi; Sakuyama, Tetsuya; Miyazaki, Takashi; Vaglarov, Bogdan S.; Fukao, Yoshio; Stern, Robert J.


    Intra-plate basalts of 35-0 Ma in East Eurasia formed in a broad backarc region above the stagnant Pacific Plate slab in the mantle transition zone. These basalts show regional-scale variations in Nd-Hf isotopes. The basalts with the most radiogenic Nd-Hf center on the Shandong Peninsula with intermediate Nd-Hf at Hainan and Datong. The least radiogenic basalts occur in the perimeters underlain by the thick continental lithosphere. Shandong basalts possess isotopic signatures of the young igneous oceanic crust of the subducted Pacific Plate. Hainan and Datong basalts have isotopic signatures of recycled subduction materials with billions of years of storage in the mantle. The perimeter basalts have isotopic signatures similar to pyroxenite xenoliths from the subcontinental lithospheric mantle beneath East Eurasia. Hainan basalts exhibit the highest mantle potential temperature (Tp), while the Shandong basalts have the lowest Tp. We infer that a deep high-Tp plume interacted with the subducted Pacific Plate slab in the mantle transition zone to form a local low-Tp plume by entraining colder igneous oceanic lithosphere. We infer that the subducted Izanagi Plate slab, once a part of the Pacific Plate mosaic, broke off from the Pacific Plate slab at 35 Ma to sink into the lower mantle. The sinking Izanagi slab triggered the plume that interacted with the stagnant Pacific slab and caused subcontinental lithospheric melting. This coincided with formation of the western Pacific backarc marginal basins due to Pacific Plate slab rollback and stagnation.

  17. GIS database and discussion for the distribution, composition, and age of Cenozoic volcanic rocks of the Pacific Northwest Volcanic Aquifer System study area (United States)

    Sherrod, David R.; Keith, Mackenzie K.


    A substantial part of the U.S. Pacific Northwest is underlain by Cenozoic volcanic and continental sedimentary rocks and, where widespread, these strata form important aquifers. The legacy geologic mapping presented with this report contains new thematic categorization added to state digital compilations published by the U.S. Geological Survey for Oregon, California, Idaho, Nevada, Utah, and Washington (Ludington and others, 2005). Our additional coding is designed to allow rapid characterization, mainly for hydrogeologic purposes, of similar rocks and deposits within a boundary expanded slightly beyond that of the Pacific Northwest Volcanic Aquifer System study area. To be useful for hydrogeologic analysis and to be more statistically manageable, statewide compilations from Ludington and others (2005) were mosaicked into a regional map and then reinterpreted into four main categories on the basis of (1) age, (2) composition, (3) hydrogeologic grouping, and (4) lithologic pattern. The coding scheme emphasizes Cenozoic volcanic or volcanic-related rocks and deposits, and of primary interest are the codings for composition and age.

  18. Nano-scale observations of interface between lichen and basaltic rock: Pseudomorphic growth of amorphous silica on augite (United States)

    Tamura, T.; Kyono, A.; Kebukawa, Y.; Takagi, S.


    Recently, lichens as the earliest colonizers of terrestrial habitats are recognized to accelerate the mineral degradation at the interface between lichens and surface rocks. Much interest has been therefore devoted in recent years to the weathering induced by the lichen colonization. Here, we report nano-scale observations of the interface between lichens and basaltic rock by TEM and STXM techniques. Some samples of basaltic rocks totally covered by lichens were collected from the 1986 lava flows on the northwest part of Izu-Oshima volcano, Japan. To prepare specimens for the nano-scale observation, we utilized the focused ion beam (FIB) system. The microstructure and local chemistry of the specimens were thoroughly investigated by TEM equipped with energy-dispersive X-ray spectroscopy (EDX). Chemical components and chemical heterogeneity at the interface were observed by scanning transmission X-ray microscopy (STXM) at Advanced Light Source branch line The collected rocks were classified into the augite-pigeonite-bronzite basalt including 6 to 8% plagioclase phenocrysts. The lichens adhering to the rocks were mainly Stereocaulon vesuvianum, fruticose lichen, which are widespread over the study area. The metabolites of the Stereocaulon vesuvianum exhibited a mean pH of 4.5 and dominance by acids. The STEM-EDX observations revealed that the interface between augite and the lichen was completely covered with amorphous silica multilayer with a thickness of less than 1 µm. Ca L-edge XANES spectra of the augite showed that the energy profile of the absorption edge at 349 eV was varied with the depth from the surface, indicating that the M2 site coordination accommodating Ca2+ undergoes significant change in shape as a function of distance from the surface. This behavior results from the fact that the M2 site is more distorted and more flexible in the C2/c clinopyroxene phase. Taking into consideration that the S. vesuvianum can produce acidic organic compounds

  19. Constraining the Origin of Basaltic Volcanic Rocks Observed by Opportunity Along the Rim of Endeavour Crater (United States)

    Bouchard, M. C.; Jolliff, B. L.; Farrand, W. H.; Mittlefehldt, D. W.


    The Mars Exploration Rover (MER) Opportunity continues its exploration along the rim of Endeavour Crater. While the primary focus for investigation has been to seek evidence of aqueous alteration, Opportunity has observed a variety of rock types, including some that are hard and relatively unaltered. These rocks tend to occur most commonly as "float rocks" or "erratics" where the geologic setting does not clearly reveal their origin. Along the rim of Endeavour crater (Fig. 1), such rocks, commonly noted in Panoramic Camera (Pancam) left eye composites as "blue rocks", are abundant components of some of the Endeavour crater rim deposits, scree slopes, and colluvium deposits. In this abstract, we examine the similarity of several of these rocks analyzed using Opportunity's Alpha Particle X-Ray Spectrometer (APXS), images and color from the Pancam, and textures observed with the Microscopic Imager (MI. At issue is the blue rocks origin; are they impact melt or volcanic, what is their age relative to Endeavour crater, and how they are related to each other?

  20. Al-augite and Cr-diopside ultramafic xenoliths in basaltic rocks from western United States (United States)

    Wilshire, H.G.; Shervais, J.W.


    Ultramafic xenoliths in basalts from the western United States are divided into Al-augite and Cr-diopside groups. The Al-augite group is characterized by Al, Ti-rich augites, comparatively Fe-rich olivine and orthopyroxene, and Al-rich spinel, the Cr-diopside group by Cr-rich clinopyroxene and spinel and by Mg-rich olivine and pyroxenes. Both groups have a wide range of subtypes, but the Al-augite group is dominated by augite-rich varieties, and the Cr-diopside group by olivine-rich lherzolites. ?? 1975.

  1. Application of nuclear analytical techniques to trace elements in cenozoic basalt and their mantle xenoliths from Aershan area in Inner Mongolia, China

    International Nuclear Information System (INIS)

    Yu Fusheng; Han Song; Huang Yuying; He Wei; Cao Jie; Wang Hongyue


    Basaltic samples from different locations in Aershan area determined by instrumental neutron activation analysis (INAA) have the same distribution patterns of REE and trace elements. The similar REE contents of the same minerals without inclusions from different xenolith suggest that the mantle source region under different active volcanoes have the same composition. The REE content differences between the same minerals with and without melt inclusions selected from the same mantle xenolith indicate that the melt inclusions are rich in REE. The same patterns of trace elements of inclusions and host minerals from different xenolith analyzed by SRXRF suggest that the mantle fluid has no notable heterogeneity in Aershan area. (authors)

  2. Scoping study of salt domes, basalts and crystalline rock as related to long term risk modeling for deep geologic disposal of nuclear waste

    International Nuclear Information System (INIS)


    Purpose is to provide a preliminary geotechnical data base sufficient to initiate the development of Long-Term Risk Models for salt domes, basalt, and crystalline rock. Geology, hydrology, specific sites, and potential release pathways are considered for each type. A summary table of site suitability characteristics is presented

  3. Genesis of Cenozoic intraplate high Mg# andesites in Northeast China (United States)

    Liu, J. Q.; Chen, L. H.; Zhong, Y.; Wang, X. J.


    High-Mg# andesites (HMAs) are usually generated in the converged plate boundary and have genetic relationships with slab subduction. However, it still remained controversial about the origin of those HMAs erupted in the intra-plate setting. Here we present major, trace element, and Sr-Nd-Pb-Hf isotopic compositions for the Cenozoic intra-plate HMAs from Northeast China to constrain their origin and formation process. Cenozoic Xunke volcanic rocks are located in the northern Lesser Khingan Range, covering an area of about 3, 000 km2. These volcanic rocks are mainly basaltic andesite and basaltic trachyandesite, with only several classified as trachyandesite and andesites. They have high SiO2 contents (54.3-57.4 wt%) and Mg# (49.6-57.8), falling into the scope of high Mg# andesites. The Xunke HMAs are enriched in large ion lithophile elements but depleted in high field strength elements, with positive Ba, K, Sr and negative Zr-Hf, and Ti anomalies. Their trace element absolute concentrations are between those of potassic basalts and Wuchagou HMAs. The Xunke HMAs have relatively enriched Sr-Nd-Hf isotopes (87Sr/86Sr = 0.705398-0.705764, ɛNd=-8.8-3.8, ɛHf=0.5-11.7), and low radiogenic Pb isotopes (206Pb/204Pb = 16.701-17.198), towards to the EM1 end-member, which indicates that they are ultimately derived from ancient, recycled crustal components. Primitive silica-rich melts were generated from higher degrees of partial melting of recycled crustal materials (relative to potassic basalts) and then interacted with the peridotite to produce the Xunke HMAs.

  4. Origin of the volcanic rocks erupted in the eastern Manus Basin: Basaltic andesite-andesite-dacite associations (United States)

    Ma, Yao; Zeng, Zhigang; Chen, Shuai; Yin, Xuebo; Wang, Xiaoyuan


    There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional crystallization of parent magma, and 4) magma mixing of mafic magmas with dacitic/rhyolitic magmas. Volcanic rocks series ranging from basaltic andesite to dacite (SiO2 ranges from 53.8 to 63.0 wt.%) from the eastern Manus Basin were detected for major and trace element compositions to understand their origin. Low H2O contents, positive correlations of La-SiO2 and Yb-SiO2, oxygen isotope data and the indistinct change of trace element concentrations in oscillatory zoning of plagioclase phenocrysts rule out the models in which silicic lava results from direct melting of hydrous mantle, partial melting of altered oceanic crust or gabbros, and magma mixing, respectively. Besides, the geochemical data of whole rock and melt inclusions indicate that fractional crystallization plays a dominant role in generating the intermediate lava with subduction features.

  5. Rock mechanics methods and in situ heater tests for design of a nuclear waste repository in basalt

    International Nuclear Information System (INIS)

    Board, M.P.


    Methods of integrating data from the Near-Surface Test Facility into the overall Waste Isolation Program are examined. Discussions are presented dealing primarily with the application of numerical models to the design of a waste repository. The various types of models currently available are discussed with reference to design in basalt and the breakdown of the problem of repository design is summarized. It is shown that the most efficient method for analyzing repository design is to break the problem down into several problems which are based on physical scale. These include the area directly surrounding a single waste canister (the very near field), the area including many canisters and canister emplacement rooms (the near field), and the area including the entire repository and the rock mass to the free surface (the far field). The methods by which numerical models are used for design are discussed. Flow charts are used to show the basic input data required, the calculational processes used, and the preliminary criteria for judgment of suitable repository performance. It is shown that the ultimate design of the allowable gross thermal loading density, and, thus, the layout of the underground workings is highly dependent upon the rock mass properties supplied as base line input data to the numerical models. Of the many input properties required, the thermal conductivity, the thermal expansion coefficient, and elastic moduli of the rock mass have, perhaps, the greatest effect on the calculation of induced temperatures, stresses, and displacements and, thus, repository design. To ensure that the design continues with confidence, field (in situ) values of input data must be obtained. The role of the Near-Surface Test Facility in situ testing in obtaining these basic required data is discussed

  6. The Impact of Space Flight on Survival and Interaction of Cupriavidus metallidurans CH34 with Basalt, a Volcanic Moon Analog Rock

    Directory of Open Access Journals (Sweden)

    Natalie Leys


    Full Text Available Microbe-mineral interactions have become of interest for space exploration as microorganisms could be used to biomine from extra-terrestrial material and extract elements useful as micronutrients in life support systems. This research aimed to identify the impact of space flight on the long-term survival of Cupriavidus metallidurans CH34 in mineral water and the interaction with basalt, a lunar-type rock in preparation for the ESA spaceflight experiment, BIOROCK. Therefore, C. metallidurans CH34 cells were suspended in mineral water supplemented with or without crushed basalt and send for 3 months on board the Russian FOTON-M4 capsule. Long-term storage had a significant impact on cell physiology and energy status (by flow cytometry analysis, plate count and intracellular ATP measurements as 60% of cells stored on ground lost their cell membrane potential, only 17% were still active, average ATP levels per cell were significantly lower and cultivability dropped to 1%. The cells stored in the presence of basalt and exposed to space flight conditions during storage however showed less dramatic changes in physiology, with only 16% of the cells lost their cell membrane potential and 24% were still active, leading to a higher cultivability (50% and indicating a general positive effect of basalt and space flight on survival. Microbe-mineral interactions and biofilm formation was altered by spaceflight as less biofilm was formed on the basalt during flight conditions. Leaching from basalt also changed (measured with ICP-OES, showing that cells release more copper from basalt and the presence of cells also impacted iron and magnesium concentration irrespective of the presence of basalt. The flight conditions thus could counteract some of the detrimental effects observed after the 3 month storage conditions.

  7. Rb-Sr and Sm-Nd whole rock analyses of basalts of the Grao Para Group, Serra dos Carajas, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Olszewski, W.J. Jr.; Gibbs, A.K.; Wirth, K.R.


    The Grao Para Group at Serra dos Carajas in the Guapore Shield of Brazil is a 6 km thick sequence of bimodal metavolcanic rock with interbedded iron formations. Rhyolites are a minor part of the low grade meta-volcanic section, with the bulk consisting of subalkaline basalt, basaltic andesite, and shoshonite. Rb-Sr whole rock analyses of 7 basalts yield an age of 2687 +/- 54 Ma. This agrees well with an age of 2758 +/- 39 Ma from zircon U-Pb analyses of the interbedded rhyolites. Except for the allocthonous Imataca Complex of Venezuela, these dates for the Grao Para Group are the first well-constrained Archean ages from the Amazonian Craton. An even older age for the basement to the Grao Para Group is also implied. Sm-Nd whole-rock analyses of four of these basalts did not yield an isochron because of the limited range of /sup 147/Sm//sup 144/Nd values, but element of/sub Nd/ values relative to CHUR were calculated using the Rb-Sr age. The typical LREE-enrichment, lack of Ce depletion or spilitic alteration of alkalies, and the high Sr initial ratios, may indicate that these isotopic patterns were derived by incorporation of some older continental crust in the mafic melts. These data together with an element of/sub Sr/ of +63.6 might indicate significant seawater exchange with volcanic rocks derived from mantle with chondritic REE patterns. This demonstrates the presence of significant continental crust in the Archean and seawater-volcanic rock interaction in a rifting environment similar to modern analogs.

  8. Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric pCO2 from weathering of basaltic provinces on continents drifting through the equatorial humid belt

    Directory of Open Access Journals (Sweden)

    D. V. Kent


    -feedback mechanism that (usually inhibits the complete collapse of atmospheric pCO2 is the accelerating formation of thick cation-deficient soils that retard chemical weathering of the underlying bedrock. Nevertheless, equatorial climate seems to be relatively insensitive to pCO2 greenhouse forcing and thus with availability of some rejuvenating relief as in arc terranes or thick basaltic provinces, silicate weathering in this venue is not subject to a strong negative feedback, providing an avenue for ice ages. The safety valve that prevents excessive atmospheric pCO2 levels is the triggering of silicate weathering of continental areas and basaltic provinces in the temperate humid belt. Excess organic carbon burial seems to have played a negligible role in atmospheric pCO2 over the Late Cretaceous and Cenozoic.

  9. Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge Mts. (Bohemia/Saxony), and their relation to mineral chemistry

    Czech Academy of Sciences Publication Activity Database

    Schnabl, Petr; Novák, Jiří Karel; Cajz, Vladimír; Lang, Miloš; Balogh, K.; Pécskay, Z.; Chadima, Martin; Šlechta, Stanislav; Kohout, Tomáš; Pruner, Petr; Ulrych, Jaromír


    Roč. 54, č. 1 (2010), s. 77-94 ISSN 0039-3169 R&D Projects: GA AV ČR IAA300130706 Institutional research plan: CEZ:AV0Z30130516 Keywords : high-Ti basaltic rocks * magnetic petrology * thermomagnetic experiments * Curie temperature variation * field-dependent susceptibility * Ohře/Eger Rift Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.123, year: 2010

  10. Late Cenozoic structure and stratigraphy of south-central Washington

    International Nuclear Information System (INIS)

    Reidel, S.P.; Fecht, K.R.; Lindsey, K.A.


    The structural framework of the Columbia Basin began developing before Columbia River Basalt Group (CRBG) volcanism. Prior to 17.5 Ma, the eastern part of the basin was a relatively stable area, with a basement of Paleozoic and older crystalline rock. The western part was an area of subsidence in which large volumes of sediment and volcanic rocks accumulated. Concurrent with eruption of the CRBG, anticlinal ridges of the Yakima Fold Belt (YFB) were growing under north-south compression. Topographic expression of these features was later masked by the large volume of CRBG basalt flowing west from fissures in the eastern Columbia Basin. The folds continued to develop after cessation of volcanism, leading to as much as 1,000 m of structural relief in the past 10 million years. Post-CRBG evolution of the Columbia Basin is recorded principally in folding and faulting in the YFB and sediments deposited in the basins. The accompanying tectonism resulted in lateral migration of major depositional systems into subsiding structural lows. Although known late Cenozoic faults are on anticlinal ridges, earthquake focal mechanisms and contemporary strain measurements indicate most stress release is occurring in the synclinal areas under north-south compression. There is no obvious correlation between focal mechanisms for earthquakes whose foci are in the CRBG and the location of known faults. High in situ stress values help to explain the occurrence of microseismicity in the Columbia Basin but not the pattern. Microseismicity appears to occur in unaltered fresh basalt. Faulted basalt associated with the YFB is highly brecciated and commonly altered to clay. The high stress, abundance of ground water in confined aquifers of the CRBG, and altered basalt in fault zones suggest that the frontal faults on the anticlinal ridges probably have some aseismic deformation. 85 refs

  11. Late Cenozoic structure and stratigraphy of south-central Washington

    Energy Technology Data Exchange (ETDEWEB)

    Reidel, S.P. [Westinghouse Hanford Co., Richland, WA (United States)]|[Washington State Univ., Pullman, WA (United States). Dept. of Geology; Campbell, N.P. [Yakima Valley Coll., WA (United States); Fecht, K.R.; Lindsey, K.A. [Westinghouse Hanford Co., Richland, WA (United States)


    The structural framework of the Columbia Basin began developing before Columbia River Basalt Group (CRBG) volcanism. Prior to 17.5 Ma, the eastern part of the basin was a relatively stable area, with a basement of Paleozoic and older crystalline rock. The western part was an area of subsidence in which large volumes of sediment and volcanic rocks accumulated. Concurrent with eruption of the CRBG, anticlinal ridges of the Yakima Fold Belt (YFB) were growing under north-south compression. Topographic expression of these features was later masked by the large volume of CRBG basalt flowing west from fissures in the eastern Columbia Basin. The folds continued to develop after cessation of volcanism, leading to as much as 1,000 m of structural relief in the past 10 million years. Post-CRBG evolution of the Columbia Basin is recorded principally in folding and faulting in the YFB and sediments deposited in the basins. The accompanying tectonism resulted in lateral migration of major depositional systems into subsiding structural lows. Although known late Cenozoic faults are on anticlinal ridges, earthquake focal mechanisms and contemporary strain measurements indicate most stress release is occurring in the synclinal areas under north-south compression. There is no obvious correlation between focal mechanisms for earthquakes whose foci are in the CRBG and the location of known faults. High in situ stress values help to explain the occurrence of microseismicity in the Columbia Basin but not the pattern. Microseismicity appears to occur in unaltered fresh basalt. Faulted basalt associated with the YFB is highly brecciated and commonly altered to clay. The high stress, abundance of ground water in confined aquifers of the CRBG, and altered basalt in fault zones suggest that the frontal faults on the anticlinal ridges probably have some aseismic deformation. 85 refs.

  12. Exploration of microbial diversity and community structure of Lonar Lake: the only hypersaline meteorite crater lake within basalt rock

    Directory of Open Access Journals (Sweden)

    Dhiraj ePaul


    Full Text Available Lonar Lake is a hypersaline and hyperalkaline soda lake and the only meteorite impact crater in the world created in the basalt rocks. Although culture-dependent studies have been reported, the comprehensive understanding of microbial community composition and structure of Lonar Lake remain obscure. In the present study, microbial community structure associated with Lonar Lake sediment and water samples was investigated using high throughput sequencing. Microbial diversity analysis revealed the existence of diverse, yet near consistent community composition. The predominance of bacterial phyla Proteobacteria (30% followed by Actinobacteria (24%, Firmicutes (11% and Cyanobacteria (5% was observed. Bacterial phylum Bacteroidetes (1.12%, BD1-5 (0.5%, Nitrospirae (0.41% and Verrucomicrobia (0.28% were detected as relatively minor populations in Lonar Lake ecosystem. Within Proteobacteria, Gammaproteobacteria represented the most abundant population (21-47% among all the sediments and as a minor population in water samples. Bacterial members Proteobacteria and Firmicutes were present significantly higher (p≥0.05 in sediment samples, whereas members of Actinobacteria, Candidate_division_TM7 and Cyanobacteria (p≥0.05 were significantly abundant in water samples. It was noted that compared to other hypersaline soda lakes, Lonar Lake samples formed one distinct cluster, suggesting a different microbial community composition and structure. The present study reports for the first time the different composition of indigenous microbial communities between the sediment and water samples of Lonar Lake. Having better insight of community structure of this Lake ecosystem could be useful in understanding the microbial role in the geochemical cycle for future functional exploration of the unique hypersaline Lonar Lake.

  13. Carbonation processes of basalts and ultra-basic rocks in subsurface conditions

    International Nuclear Information System (INIS)

    Daval, D.


    For mitigating against rising levels of carbon dioxide (CO 2 ) in the atmosphere, several ways are envisaged to store it geologically. Among them, mineral trapping by carbonation of basic and ultra-basic rocks is thought to be the safest. However, little is known about the reaction kinetics and mechanisms of the process, which would ultimately make us able to foresee the fate of CO 2 over long time spans, and possibly enhance the efficiency of the mineral trapping. As a consequence, this thesis aimed at bringing new constrains on the weathering processes of (ultra)basic silicates, with (or without) high pCO 2 . Original experimental data of dissolution and carbonation processes were acquired on five silicates: wollastonite (CaSiO 3 ), forsterite (Mg 2 SiO 4 ), diopside (CaMgSi 2 O 6 ), lizardite (Mg 3 Si 2 O 5 (OH) 4 ) and fayalite (Fe 2 SiO 4 ). The main parameters which could affect the rates of carbonation were assessed: role and mechanism of formation of passivating layers, saturation state of the fluid, specific effect of CO 2 and behaviour of iron (II). Each mineral was thought to be relevant to bring new insights on each one of these questions. Wollastonite carbonation was first investigated in batch reactors. At 90 C and pCO 2 = 25 MPa, the reaction reaches completion within a couple of days. The measured carbonation rate is similar to the modelled one, indicating that the rate-limiting step of the process is wollastonite dissolution. Consequently, the thick amorphous silica coatings (≥ 100 μm) that form onto wollastonite surface do not prevent the fluid to reach the pristine mineral. This result is in agreement with the structure of the silica coating, determined to be meso-porous at the nm-scale. Besides, the chemical gradient of calcium across the silica layer suggests that it is formed by a dissolution-precipitation mechanism instead of a solid-state diffusion mechanism. On the other hand, the dissolution of forsteritic olivine is inhibited by the

  14. Petrogenesis of basaltic volcanic rocks from the Pribilof Islands, Alaska, by melting of metasomatically enriched depleted lithosphere, crystallization differentiation, and magma mixing (United States)

    Chang, J.M.; Feeley, T.C.; Deraps, M.R.


    The Pribilof Islands, Alaska, are located in the Bering Sea in a continental intraplate setting. In this study we examine the petrology and geochemistry of volcanic rocks from St. Paul (0??54-0??003 Ma) and St. George (2??8-1??4 Ma) Islands, the two largest Pribilof Islands. Rocks from St. George can be divided into three groups: group 1 is a high-MgO, low-SiO. 2 suite composed primarily of basanites; group 2 is a high-MgO, high-SiO 2 suite consisting predominantly of alkali basalts; group 3 is an intermediate- to low-MgO suite that includes plagioclase-phyric subalkali basalts and hawaiites. Major and trace element geochemistry suggests that groups 1 and 2 formed by small-degree partial melting of amphibole-bearing to amphibole-free garnet peridotite. Group 1 rocks were the earliest melts produced from the most hydrous parts of the mantle, as they show the strongest geochemical signature of amphibole in their source. The suite of rocks from St. Paul ranges from 14??4 to 4??2 wt % MgO at relatively constant SiO 2 contents (43??1-47??3 wt %). The most primitive St. Paul rocks are modeled as mixtures between magmas with compositions similar to groups 1 and 2 from St. George Island, which subsequently fractionated olivine, clinopyroxene, and spinel to form more evolved rocks. Plagioclase-phyric group 3 rocks from St. George are modeled as mixtures between an evolved melt similar to the evolved magmas on St. Paul and a fractionated group 2 end-member from St. George. Mantle potential temperatures estimated for primitive basanites and alkali basalts are ???1400??C and are similar to those of mid-ocean ridge basalts (MORB). Similarly, 87Sr/. 86Sr and 143Nd/. 144Nd values for all rocks are MORB-like, in the range of 0??702704-0??703035 and 0??513026-0??513109, respectively. 208Pb/. 204Pb vs 206Pb/. 204Pb values lie near the MORB end-member but show a linear trend towards HIMU (high time-integrated 238U/. 204Pb). Despite isotopic similarities to MORB, many of the major and

  15. Mineral CO2 sequestration in basalts and ultra-basic rocks: impact of secondary silicated phases on the carbonation process

    International Nuclear Information System (INIS)

    Sissmann, Olivier


    The formation of carbonates constitutes a stable option for carbon dioxide (CO 2 ) geological sequestration, and is prone to play a significant role in reducing emissions of anthropic origin. However, our comprehension of the carbonation mechanism, as well as of the kinetics limitations encountered during this chemical reaction, remains poorly developed. Though there is a large number of studies focusing on the dissolution kinetics of basic silicates and on the precipitation of carbonates, few have inquired about the impact that the formation of non-carbonated secondary phases can have on these reaction's kinetics. It is the approach chosen here, as only solid knowledge of the global carbonation mechanism can make this process predictive and efficient. Experimental data on dissolution and carbonation have therefore been determined in batch reactors, on relevant minerals and rocks. Firstly, we studied the carbonation of olivine (a major phase within peridotites and minor within basalts) at 90 deg. C and under pCO 2 of 280 bars. The dissolution of San Carlos olivine (Mg 1.76 Fe 0.24 SiO 4 ) is slowed down by the formation of a surface silica gel, when the fluid reaches equilibrium with amorphous silica. The transport of species to the reactive medium becomes the limiting step of the process, slowing down the dissolution process of San Carlos olivine by 5 orders of magnitude. However, this passivation doesn't occur during the alteration of Ca-olivine (Ca 2 SiO 4 ), though a surface silica layer does form. This comparison suggests that it isn't the structure of the silicate but its chemical composition, which controls the transport properties through the interfacial layer. The second part explores the effects of organic ligands and of temperature variations on the formation of those phases. The addition of citrate at 90 deg. C increases the kinetics of San Carlos olivine by one order of magnitude, and allows the release of enough Mg in the aqueous medium to form

  16. A potpourri of pristine moon rocks, including a VHK mare basalt and a unique, augite-rich Apollo 17 anorthosite (United States)

    Warren, P. H.; Shirley, D. N.; Kallemeyn, G. W.


    The anorthosite fragment, 76504,18, the first of the Apollo 17's pristine anorthosites, was found to have: (1) a higher ratio of high-Ca pyroxine to low-Ca pyroxene, (2) higher Na in its plagioclase, (3) higher contents of incompatible elements, and (4) a higher Eu/Al ratio in comparison to ferroan anorthosites. With a parent melt having a negative Eu anomaly, 76504,18 closely resembles a typical mare basalt. This anorthosite was among the latest to be formed by plagioclase flotation above a primordial magmasphere; typical mare basalt regions accumulated at about the same time or even earlier. Another fragment 14181c, a very high potassium basalt, was studied and found to be similar to typical Apollo 14 mare basalt though it has a K/La ratio of 1050. It is suggested that this lithology formed after a normal Apollo 14 mare basaltic melt partially assimilated granite. New data for siderphile elements in Apollo 12 mare basalts indicate that only the lowest of earlier data are trustworthy as being free of laboratory contamination.

  17. Continental basalts record the crust-mantle interaction in oceanic subduction channel: A geochemical case study from eastern China (United States)

    Xu, Zheng; Zheng, Yong-Fei


    Continental basalts, erupted in either flood or rift mode, usually show oceanic island basalts (OIB)-like geochemical compositions. Although their depletion in Sr-Nd isotope compositions is normally ascribed to contributions from the asthenospheric mantle, their enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE) is generally associated with variable enrichments in the Sr-Nd isotope compositions. This indicates significant contributions from crustal components such as igneous oceanic crust, lower continental crust and seafloor sediment. Nevertheless, these crustal components were not incorporated into the mantle sources of continental basalts in the form of solidus rocks. Instead they were processed into metasomatic agents through low-degree partial melting in order to have the geochemical fractionation of the largest extent to achieve the enrichment of LILE and LREE in the metasomatic agents. Therefore, the mantle sources of continental basalts were generated by metasomatic reaction of the depleted mid-ocean ridge basalts (MORB) mantle with hydrous felsic melts. Nevertheless, mass balance considerations indicate differential contributions from the mantle and crustal components to the basalts. While the depleted MORB mantle predominates the budget of major elements, the crustal components predominate the budget of melt-mobile incompatible trace elements and their pertinent radiogenic isotopes. These considerations are verified by model calculations that are composed of four steps in an ancient oceanic subduction channel: (1) dehydration of the subducting crustal rocks at subarc depths, (2) anataxis of the dehydrated rocks at postarc depths, (3) metasomatic reaction of the depleted MORB mantle peridotite with the felsic melts to generate ultramafic metasomatites in the lower part of the mantle wedge, and (4) partial melting of the metasomatites for basaltic magmatism. The composition of metasomatites is quantitatively dictated by

  18. High-Ti basaltic rocks in the uplifted shoulder of the Ohre (Eger) Rift, western Bohemia/Saxony

    Czech Academy of Sciences Publication Activity Database

    Novák, Jiří Karel; Ulrych, Jaromír; Ackerman, Lukáš; Jelínek, E.; Chadima, Martin; Mizera, Jiří; Řanda, Zdeněk


    Roč. 34, 4/6 (2008), s. 1325145-1325145 ISSN 0161-6951. [International Geological Congress /33./. 06.08.2008-14.08.2008, Oslo ] R&D Projects: GA AV ČR IAA300130706 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10480505 Keywords : high -Ti basalts * Krušné hory/Erzgebirge * Eger Rift * magnetic properties Subject RIV: DB - Geology ; Mineralogy

  19. Temporal and geochemical evolution of the Cenozoic intraplate volcanism of Zealandia (United States)

    Timm, Christian; Hoernle, Kaj; Werner, Reinhard; Hauff, Folkmar; van den Bogaard, Paul; White, James; Mortimer, Nick; Garbe-Schönberg, Dieter


    In order to constrain better the distribution, age, geochemistry and origin of widespread Cenozoic intraplate volcanism on Zealandia, the New Zealand micro-continent, we report new 40Ar/ 39Ar and geochemical (major and trace element and Sr-Nd-Hf-Pb isotope) data from offshore (Chatham Rise, Campbell and Challenger Plateaus) and onland (North, South, Auckland, Campbell, Chatham and Antipodes Islands of New Zealand) volcanism on Zealandia. The samples include nephelinite, basanite through phonolite, alkali basalt through trachyte/rhyolite, and minor tholeiite and basaltic andesite, all of which have ocean island basalt (OIB)-type trace element signatures and which range in age from 64.8 to 0.17 Ma. Isotope ratios show a wide range in composition ( 87Sr/ 86Sr = 0.7027-0.7050, 143Nd/ 144Nd = 0.5128-0.5131, 177Hf/ 176Hf = 0.2829-0.2831, 206Pb/ 204Pb = 18.62-20.67, 207Pb/ 204Pb = 15.54-15.72 and 208Pb/ 204Pb = 38.27-40.34) with samples plotting between mid-ocean-ridge basalts (MORB) and Cretaceous New Zealand intraplate volcanic rocks. Major characteristics of Zealandia's Cenozoic volcanism include longevity, irregular distribution and lack of age progressions in the direction of plate motion, or indeed any systematic temporal or spatial geochemical variations. We believe that these characteristics can be best explained in the context of lithospheric detachment, which causes upwelling and melting of the upper asthenospheric mantle and portions of the removed lithosphere. We propose that a large-scale seismic low-velocity anomaly, that stretches from beneath West Antarctica to Zealandia at a depth of > 600 km may represent a geochemical reservoir that has been in existence since the Cretaceous, and has been supplying the upper mantle beneath Zealandia with HIMU-type plume material throughout the Cenozoic. In addition, the sources of the Cenozoic intraplate volcanism may be at least partially derived through melting of locally detached Zealandia lower lithosphere.

  20. Contrasting Nature of Magnetic Anomalies over Thin Sections Made out of Barrandien’s Basaltic Rocks Points to their Origin

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther; Pruner, Petr; Schnabl, Petr; Šifnerová, Kristýna

    -, special issue (2012), s. 69-70 ISSN 1335-2806. [Castle meeting New Trends in Geomagnetism : Paleo, rock and environmental magnetism/13./. 17.06.2012-23.06.2012, Zvolen] R&D Projects: GA ČR GAP210/10/2351 Institutional support: RVO:67985831 Keywords : magnetic anomalies * thin sections * volcanic rocks Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  1. Technological characterization of basaltic rocks of Canoas I Hydroelectric Power Plant, Paranapanema river, Sao Paulo - Parana states, Brazil; Caracterizacao tecnologica das rochas basalticas da Usina Hidroeletrica Canoas I, Rio Paranapanema, SP/PR

    Energy Technology Data Exchange (ETDEWEB)

    Marrano, Antonio


    Basaltic litotypes from the rock mass foundation of Canoas I Hydroelectric Power Plant were submitted to technological characterization tests, in order to verify their suitability as construction material. Physical and mechanical properties (density, porosity, water absorption, ultrasonic velocity, compressive and splitting tensile strength, among others) were determined, besides petrographic analyses. Weather ability tests were also performed, not only through wetting-drying cycles and by immersion in ethylene glycol but by outdoor exposure as well, using crushed and core drilled specimens. Detailed procedures for the weather ability test using core specimens from rotary drilling are given. It is analyzed the influence of a geological feature (fault zone, about 10 meters thick and 20 degrees dip), that occurs in the rock mass foundation, on the technological properties of these rocks. Basaltic litotypes selected as construction material are then pointed out. (author)

  2. Proceedings of the fifth international groundwater conference on the assessment and management of groundwater resources in hard rock systems with special reference to basaltic terrain

    International Nuclear Information System (INIS)

    Thangarajan, M.; Mayilswami, C.; Kulkarni, P.S.; Singh, V.P.


    Groundwater resources in hard rock regions with limited renewable potential have to be managed judiciously to ensure adequate supplies of dependable quantity and quality. It is a natural resource with economic, strategic and environmental value, which is under stress both due to changing climatic and anthropogenic factors. Therefore the management strategies need to be aimed at sustenance of this limited resource. In India, and also elsewhere in the world major parts of the semi-arid regions are characterized by hard rocks and it is of vital importance to understand the nature of the aquifer systems and its current stress conditions. Though the achievements through scientific development in exploration and exploitation are commendable, it has adversely affected the hard rock aquifer system, both in terms of quantity and quality; which is of major concern today. In order to reverse the situation, better management strategy of groundwater resources needs to be devised for prevention of further degradation of quality and meeting out the future demand of quantity. This necessitates: understanding the flow mechanism, evaluating the potential and evolving optimal utilization schemes, and assessing and monitoring quality in the changing scenario of anthropogenically induced agricultural, urban, industrial and climatic change. The groundwater flow mechanism through fractures in hard rocks is yet to be fully understood in terms of fracture geometry and its relation to groundwater flow. The characterization of flow geometry in basaltic aquifer is yet to be fully explored. Groundwater pollution due to anthropogenic factors is very slow process with long-term impacts on carbon cycle and global climatic change on one hand and quality on the other. It is generally recognized that the prevention of groundwater pollution is cheaper than its remedial measures in the long run. Furthermore, because of the nature of groundwater flow and the complexity and management uncertainty of

  3. Olivine and melt inclusion chemical constraints on the source of intracontinental basalts from the eastern North China Craton: Discrimination of contributions from the subducted Pacific slab (United States)

    Li, Hong-Yan; Xu, Yi-Gang; Ryan, Jeffrey G.; Huang, Xiao-Long; Ren, Zhong-Yuan; Guo, Hua; Ning, Zhen-Guo


    Contributions from fluid and melt inputs from the subducting Pacific slab to the chemical makeup of intraplate basalts erupted on the eastern Eurasian continent have long been suggested but have not thus far been geochemically constrained. To attempt to address this question, we have investigated Cenozoic basaltic rocks from the western Shandong and Bohai Bay Basin, eastern North China Craton (NCC), which preserve coherent relationships among the chemistries of their melt inclusions, their hosting olivines and their bulk rock compositions. Three groups of samples are distinguished: (1) high-Si and (2) moderate-Si basalts (tholeiites, alkali basalts and basanites) which were erupted at ∼23-20 Ma, and (3) low-Si basalts (nephelinites) which were erupted at <9 Ma. The high-Si basalts have lower alkalies, CaO and FeOT contents, lower trace element concentrations, lower La/Yb, Sm/Yb and Ce/Pb but higher Ba/Th ratios, and lower εNd and εHf values than the low-Si basalts. The olivines in the high-Si basalts have higher Ni and lower Mn and Ca at a given Fo value than those crystallizing from peridotite melts, and their corresponding melt inclusions have lower CaO contents than peridotite melts, suggesting a garnet pyroxenitic source. The magmatic olivines from low-Si basalts have lower Ni but higher Mn at a given Fo value than that of the high-Si basalts, suggesting more olivine in its source. The olivine-hosted melt inclusions of the low-Si basalts have major elemental signatures different from melts of normal peridotitic or garnet pyroxenitic mantle sources, pointing to their derivation from a carbonated mantle source consisting of peridotite and garnet pyroxenite. We propose a model involving the differential melting of a subduction-modified mantle source to account for the generation of these three suites of basalts. Asthenospheric mantle beneath the eastern NCC, which entrains garnet pyroxenite with an EM1 isotopic signature, was metasomatized by carbonatitic

  4. Present status of the interlaboratorial co-operative study for standards rocks of granite (GB-1) and basalt (BB-1) from the Geochemistry Department of I.G.U.F. Ba./Brazil

    International Nuclear Information System (INIS)

    Linhares, P.S.


    Results for major, minor and trace elements obtained by twelve laboratories for the standards rocks, Granite (GB-1) and Basalte (BB-1), of the Geochemistry Department of Geociences Institute-U-F.Ba are presented. At present status of the study it is possible to approach the most probably correct value (usable value) for the concentration of each of the major and minor elements. (author) [pt

  5. Moessbauer Studies of Volhynian Basalts

    International Nuclear Information System (INIS)

    Bakun-Czubarow, N.; Milczarski, J.; Galazka-Friedman, J.; Szlachta, K.; Forder, S.


    The Volhynian basalts studied belong to the effusive-tuffogenic Volhynian Series (Slawatycze Series in Poland), being the large Ediacaran continental igneous province, that covers an area of 200 000 km 2 in the western margin of East European Craton. The series is underlain by the Cryogenian terrigenous Polesie Series with doleritic sills and dikes. The Volhynian Series consists of the rock beds belonging to the three volcanic cycles with different ratios of flood basalts to pyroclastics. The aim of the study was recognition of primary and secondary Fe-bearing minerals, particularly Fe- and Fe-Ti oxides as well as determination of iron oxidation state, that is an important tool in the search for native copper deposits in these rocks. For Moessbauer studies the following rock samples were chosen: the Polesie Series dolerites, the Volhynian Series basalts from the Ukrainian quarries and drill-holes, e.g. from the Volodymir Volhynskaya drilling hole; the Slawatycze Series basalts from Kaplonosy drill-hole in Poland. In the Kaplonosy basalts the content of magnetite decreases with depth, which may be caused by magma differentiation due to fractional crystallization, when Mg content decreases as Ti and Fe - increases in basic magma. In the Kaplonosy basalts the Fe 2+ /Fe 3+ ratio increases with depth, which points to the increase of iron oxidation with the progress of basaltic magma differentiation. (authors)

  6. Late Cenozoic volcanism in central Myanmar: Geochemical characteristics and geodynamic significance (United States)

    Lee, Hao-Yang; Chung, Sun-Lin; Yang, Hsiao-Ming


    Late Cenozoic volcanism occurred in the central Myanmar basin, a region that is marked by the existence of the dextral Sagaing fault linking the eastern Himalayan Syntaxis to the north and the Andaman Sea to the south. Here we report new geochemical data of volcanic rocks from Monywa, Mt. Popa and Singu areas erupting in two distinct stages, i.e., mid-Miocene and Quaternary, respectively. While calc-alkaline rocks showing arc-like geochemical features are abundant, an apparent change in magma composition is observed between these two stages. The mid-Miocene rocks are mainly dominated by intermediate compositions (SiO2 = 53-61 wt.%) and typical of high-K calc-alkaline nature. They exhibit uniform Sr and Nd isotopic ratios (ISr ≈ ~ 0.705; εNd(T) = + 2.7 to + 1.6), suggesting a juvenile mantle origin related to the subduction of Indian oceanic lithosphere beneath this part of Asia. The Quaternary rocks consist mainly of basalts that, however, show variations in geochemical features. Three suites in this stage are observed: (1) calc-alkaline suite (basalts and basaltic andesites from Monywa and Mt. Popa: SiO2 = 48-56 wt.%; ISr = 0.704 to 0.705; εNd(T) = + 3.1 to + 2.1), originating from partial melting of a "remnant" juvenile mantle wedge, (2) alkali basalt suite I (basanites from Monywa: SiO2 ≈ 45 wt.%; MgO = 10-12 wt.%; K2O ≈ 2.0 wt.%; ISr = 0.704 to 0.705; εNd(T) ≈ + 3.6), interpreted as the product of small-degree melting from an amphibole lherzolite in the lithospheric mantle, and (3) alkali basalt suite II (trachybasalts from Singu: SiO2 ≈ 51 wt.%; K2O = 2.6-3.5 wt.%; ISr ≈ 0.706; εNd(T) = + 1.6 to + 0.9), interpreted as the product of partial melting from the asthenosphere. All processes of magma generation were related to the India-Asia collision that caused regional plate reorganization, a transition from oblique subduction to dextral movement in the Miocene, and subsequent "rollback" of the subducted Indian oceanic lithosphere in the

  7. Origin of co-existing basalts, high-Mg andesites, and adakites in the SW Japan hot subduction system (United States)

    Kimura, J.; Kunikiyo, T.; Osaka, I.; Shimoshioiri, Y.; Katakuse, M.; Kakubuchi, S.; Nagao, T.; Furuyama, K.; Kamei, A.; Nakajima, J.; Stern, R. J.; Gill, J. B.


    In response to subduction of the young, hot Shikoku Basin of the Philippine Sea Plate (PSP) slab, arc magmas have been active throughout the late Cenozoic (<13 Ma) in the SW Japan arc. Extremely variable magma types occurred including oceanic island-type basalt (OIB), shoshonitc to mildly alkalic to sub-alkalic basalts with arc signatures, high-Mg andesites (HMAs), and adakitic andesites and dacites. The OIB-type basalts preceded the arc-type magmas. Therefore, the transition from OIB- to arc-types was related to opening of the Japan of Sea back-arc basin and subsequent re-initiation of PSP subduction. However, both the origin and tectonic implications of this magmatism are debated. Consequently, we analyzed the bulk rock geochemistry of 340 lava samples from seven Quaternary volcanoes and investigated their sources and melting conditions using a geochemical mass balance model, Arc Basalt Simulator version 4 (ABS4). Comparison to basement granitoids precludes adakite genesis in the lower crust. Instead, the ABS4 model suggests that the adakites are mostly slab melts plus minor interaction with mantle wedge peridotite (PERID). Increasing involvement of PERID during slab melt-fluxed mantle melting explains fairly well the geochemical variations of the shoshonites, mildly alkalic to sub-alkalic basalts, and HMAs. We propose that the generation of various magma types in the late Cenozoic SW Japan arc originated simply by "slab melt-fluxed mantle melting" with large variations in melting conditions including depth, temperature, degree of melting, and flux fractions. Such volcanism has been continuous from 13 Ma (Setouchi HMA) to the present, so that the hot subduction system, involving subduction of the Shikoku Basin spreading ridge, should be continuous since 13 Ma beneath the SW Japan arc. Our results further suggest that this atypically hot system generated diverse primary arc magmas from various degrees of flux melting even though the slab source components and sub

  8. Field-trip guide to Columbia River flood basalts, associated rhyolites, and diverse post-plume volcanism in eastern Oregon (United States)

    Ferns, Mark L.; Streck, Martin J.; McClaughry, Jason D.


    The Miocene Columbia River Basalt Group (CRBG) is the youngest and best preserved continental flood basalt province on Earth, linked in space and time with a compositionally diverse succession of volcanic rocks that partially record the apparent emergence and passage of the Yellowstone plume head through eastern Oregon during the late Cenozoic. This compositionally diverse suite of volcanic rocks are considered part of the La Grande-Owyhee eruptive axis (LOEA), an approximately 300-kilometer-long (185 mile), north-northwest-trending, middle Miocene to Pliocene volcanic belt located along the eastern margin of the Columbia River flood basalt province. Volcanic rocks erupted from and preserved within the LOEA form an important regional stratigraphic link between the (1) flood basalt-dominated Columbia Plateau on the north, (2) bimodal basalt-rhyolite vent complexes of the Owyhee Plateau on the south, (3) bimodal basalt-rhyolite and time-transgressive rhyolitic volcanic fields of the Snake River Plain-Yellowstone Plateau, and (4) the High Lava Plains of central Oregon.This field-trip guide describes a 4-day geologic excursion that will explore the stratigraphic and geochemical relationships among mafic rocks of the Columbia River Basalt Group and coeval and compositionally diverse volcanic rocks associated with the early “Yellowstone track” and High Lava Plains in eastern Oregon. Beginning in Portland, the Day 1 log traverses the Columbia River gorge eastward to Baker City, focusing on prominent outcrops that reveal a distal succession of laterally extensive, large-volume tholeiitic flood lavas of the Grande Ronde, Wanapum, and Saddle Mountains Basalt formations of the CRBG. These “great flows” are typical of the well-studied flood basalt-dominated Columbia Plateau, where interbedded silicic and calc-alkaline lavas are conspicuously absent. The latter part of Day 1 will highlight exposures of middle to late Miocene silicic ash-flow tuffs, rhyolite domes, and

  9. The Origin of Basalt and Cause of Melting Beneath East Antarctica as Revealed by the Southernmost Volcanoes on Earth (United States)

    Reindel, J. L.; Panter, K. S.; Smellie, J. L.; McIntosh, W. C.


    Mt. Early and Sheridan Bluff are two basaltic monogenetic volcanoes located at 87° South latitude at the head of the Scott Glacier. These Early Miocene volcanoes lie 800 km from any other volcano and 200 km inland from the shoulder of the West Antarctic Rift System (WARS), which is the foci of most Cenozoic alkaline volcanism in Antarctica. Preliminary 40Ar/39Ar dates suggest that Mt. Early is older than previously determined and closer in age to Sheridan Bluff ( 19 Ma). Petrography, mineral chemistry and whole rock major and trace element concentrations are used to characterize the basalts and to determine whether they are genetically related to mafic volcanism in the WARS. The basalts are porphyritic with phenocrysts of olivine (Fo 58-84%), plagioclase (An 48-67%) ± clinopyroxene (Wo 43-48%). Whole rock MgO range from 10 to 4 wt.% and have restricted SiO2 (48 to 50 wt.%) contents. The basalts vary from alkaline (up to 6 wt.% Ne-normative) to subalkaline (up to 6 wt.% Hy-normative). The alkaline basalts that occur at both Mt. Early and Sheridan Bluff are more strongly enriched in incompatible elements (La 33-49 ppm, Ba 270-484 ppm, Sr 712-1009 ppm), have LaN/YbN ratios >10 and show prominent Pb negative anomalies with only slight K negative anomalies on primitive mantle normalized, multi-element diagrams. Subalkaline basalts (only at Sheridan Bluff) have lower concentrations of incompatible elements (La 14-16 ppm, Ba 110-144 ppm, and Sr 358-380 ppm), LaN/YbN ratios base of the East Antarctic craton and its replacement by warmer asthenosphere has been proposed for this region based on geophysical evidence (Heeszel et al., 2016). The volcanism may constrain the timing of this event. Heeszel et al. (2016) JGR, 121, 1758-1775.

  10. Delamination of lithospheric mantle evidenced by Cenozoic potassic rocks in Yunnan, SW China: A contribution to uplift of the Eastern Tibetan Plateau (United States)

    Chen, Bei; Long, Xiaoping; Wilde, Simon A.; Yuan, Chao; Wang, Qiang; Xia, Xiaoping; Zhang, Zhaofeng


    New zircon U-Pb ages, mineral chemical data, whole-rock geochemistry and Sr-Nd isotopes from the potassium-rich intrusions in the Yunnan area, SW China, were determined to provide constraints on the uplift of the Eastern Tibetan Plateau. The intrusive rocks consist of shoshonitic syenites (high-Mg syenites, low-Mg syenites and syenite porphyries) and potassic granitoids (granite porphyries). Zircon LA-ICP-MS U-Pb dating indicates coeval emplacement ages of 35 Ma. The shoshonitic syenites have alkaline affinities and the enrichment in LILEs and LREEs (e.g. La, Sr, U, Pb), with depletion of HFSEs (e.g. Nb, Ti, Ta) and weak Eu anomalies. They display uniform Sr-Nd-Lu-Hf isotopic compositions with similar initial 87Sr/86Sr ratios (0.7073-0.7079), enriched εNd(t) values (- 6.8 to - 4.3) and mostly negative zircon εHf(t) values ranging from - 4.6 to + 0.1. The high-Mg syenites have high MgO, Fe2O3T, TiO2, CaO, Cr, Ni concentrations and relatively high Mg# (60-68), indicating an origin from enriched lithospheric mantle. The low-Mg syenites and syenite porphyries are geochemically distinct with the high-Mg syenites, but the insignificant variations in major elements, linear trends of La against (La/Yb)N and similar Sr-Nd isotopic compositions to the high-Mg syenites suggest that they were produced by different degrees of partial melting of the same enriched mantle source. The potassic granitic intrusions are sub-alkaline with a strongly peraluminous character. They display an S-type granite affinity, with high Al2O3/TiO2 and low CaO/Na2O and K2O/Al2O3 ratios, suggesting a pelitic source. They are LREE-enriched and have relatively flat HREE patterns with weakly negative Eu anomalies and positive Rb, U, and Pb anomalies and negative Nb, Ta, and Ti anomalies. They have relatively high initial 87Sr/86Sr ratios (0.7143) and enriched Nd isotopic compositions [εNd(t) = - 4.1]. Their zircon εHf(t) values (- 4.0 to + 0.09) and old two-stage Hf model ages (TDMc = 1.16-1.36 Ga

  11. Basement and cover-rock deformation during Laramide contraction in the Northern Madison Range (Montana) and its influence on Cenozoic basin formation

    Energy Technology Data Exchange (ETDEWEB)

    Kellogg, K.S. [Geological Survey, Denver, CO (United States); Schmidt, C.J. [Western Michigan Univ., Kalamazoo, MI (United States); Young, S.W. [Conoco, Inc., Midland, TX (United States)


    Two major Laramide fault systems converge in the northwestern Madison Range: the northwest-striking, southwest-vergent Spanish Peaks reverse fault and the north-striking, east-vergent Hilgard thrust system. Analysis of foliation attitudes in basement gneiss north and south of the Spanish Peaks fault indicates that the basement in thrusted blocks of the Hilgard thrust system has been rotated by an amount similar to that of the basement-cover contact. In most places along the Hilgard thrust system, a large basement overhang, produced by thrusting of Archean blocks above rocks as young as Late Cretaceous, overlies a tight footwall syncline. This tight folding is largely concentric and was accommodated by flexural slip, resulting in severe crowding in synclinal hinges that resulted in observed or inferred features such as bedding-plane slip, imbricate and out-of-syncline thrusting, and hinge collapse. This paired fault system (the Madison normal fault system and the Hilgard thrust system) of the northern Madison Range is strikingly similar to other paired systems in southwestern Montana along and adjacent to the western margins of the Ruby Range, Snowcrest Range, Greenhorn Range, Tobacco Root Mountains, and Bridger Range. No hydrocarbon discoveries have been made in this unique structural province. However, petroleum exploration here has focused on basement-cored anticlines, both surface and subthrust, related to the two major Laramide fault systems and on the fault-bounded blocks of Tertiary rocks within the post-Laramide extensional basins. The interplay of the two Laramide fault systems during both Laramide shortening and Tertiary extension has produced a variety of possible structural traps in the Madison Range that have not yet been thoroughly investigated.

  12. Genesis of amethyst geodes in basaltic rocks of the Serra Geral Formation (Ametista do Sul, Rio Grande do Sul, Brazil): a fluid inclusion, REE, oxygen, carbon, and Sr isotope study on basalt, quartz, and calcite (United States)

    Gilg, H. Albert; Morteani, Giulio; Kostitsyn, Yuri; Preinfalk, Christine; Gatter, Istvan; Strieder, Adelir J.


    In the Ametista do Sul area, Rio Grande do Sul, Brazil, amethyst-bearing geodes are hosted by a ~40- to 50-m-thick subhorizontal high-Ti basaltic lava flow of the Lower Cretaceous Paraná Continental Flood Basalt Province. The typically spherical cap-shaped, sometimes vertically elongated geodes display an outer rim of celadonite followed inwards by agate and colorless and finally amethystine quartz. Calcite formed throughout the whole crystallization sequence, but most commonly as very late euhedral crystals, sometimes with gypsum, in the central cavity. Fluid inclusions in colorless quartz and amethyst are predominantly monophase and contain an aqueous liquid. Two-phase liquid-vapor inclusions are rare. Some with a consistent degree of fill homogenize into the liquid between 95 and 98 °C. Ice-melting temperatures in the absence of a vapor phase between -4 and +4 °C indicate low salinities. Chondrite-normalized REE patterns of calcites are highly variable and show generally no systematic correlation with the paragenetic sequence. The oxygen isotope composition of calcites is very homogeneous (δ18OVSMOW=24.9±1.1‰, n=34) indicating crystallization temperatures of less than 100 °C. Carbon isotope values of calcites show a considerable variation ranging from -18.7 to -2.9‰ (VPDB). The 87Sr/86Sr ratio of calcites varies between 0.706 and 0.708 and is more radiogenic than that of the host basalt (~0.705). The most likely source of silica, calcium, carbon, and minor elements in the infill of the geodes is the highly reactive interstitial glass of the host basalts leached by gas-poor aqueous solutions of meteoric origin ascending from the locally artesian Botucatú aquifer system in the footwall of the volcanic sequence. The genesis of amethyst geodes in basalts at Ametista do Sul, Brazil, is thus considered as a two-stage process with an early magmatic protogeode formation and a late, low temperature infill of the cavity.

  13. Cenozoic intraplate volcanism on New Zealand: Upwelling induced by lithospheric removal (United States)

    Hoernle, K.; White, J. D. L.; van den Bogaard, P.; Hauff, F.; Coombs, D. S.; Werner, R.; Timm, C.; Garbe-Schönberg, D.; Reay, A.; Cooper, A. F.


    Diffuse intraplate volcanism spanning the Cenozoic on the North, South, Chatham, Auckland, Campbell and Antipodes Islands of New Zealand has produced quartz tholeiitic to basanitic/nephelinitic (including their differentiates) monogenetic volcanic fields and large shield volcanoes. New 40Ar/ 39Ar ages, combined with published age data, show no correlations among age, location or composition of the volcanoes. Continuous volcanism in restricted areas over long time periods, and a lack of volcanic age progressions in the direction and at the rate of plate motion, are inconsistent with a plume origin for the intraplate volcanism. Although localized extension took place during some episodes of volcanic activity, the degree of extension does not correlate with erupted volumes or compositions. Major and trace element data suggest that the silica-poor volcanic rocks (primarily basanites) were derived through low degrees of partial melting at deeper depths than the more silica-rich volcanic rocks (alkali basalts and tholeiites) and that all melts were produced from ocean island basalt (OIB)-type sources, containing garnet pyroxenite or eclogite. The Sr-Nd-Pb isotope data indicate that the silica-poor rocks were derived from high time-integrated U/Pb (HIMU)-type sources and the silica-rich rocks from more enriched mantle (EM)-type sources, reflecting greater interaction with lithosphere modified by subduction beneath Gondwana. The first-order cause of melting is inferred to be decompression melting in the garnet stability field of upwelling asthenosphere, triggered by removal (detachment) of different parts of the subcontinental lithospheric keel throughout the Cenozoic. In some cases, large thicknesses of keel were removed and magmatism extended over many millions of years. Decompression melting beneath a thick craton generates melts that are likely to be similar to those from the base of the mid-ocean-ridge melting column. At mid-ocean ridges, however, these melts never

  14. Cenozoic bryozoans from Borneo

    NARCIS (Netherlands)

    Di Martino, E.


    Bryozoans are colonial marine invertebrates with an abundant fossil record ranging from Ordovician to Holocene. They are found particularly in shelf sediments deposited at all palaeolatitudes. The Cenozoic bryozoan fauna of Indonesia has been severely neglected in the past. The paucity of previous

  15. Geology and petrography of the basaltic rocks (Arapey formation) cropping out in toad 4 between Arapey river (92 km) and Artigas (200 Km)

    International Nuclear Information System (INIS)

    Oyhantcabal, P.; Pineiro, G.


    This contribution presents a geological map of the basaltic flows of Arapey formation (Mezosoic) cropping out in Road 4 between the Arapey river (92 Km) and Artigas city (200 Km) together with the description of the petrographic features of the different portions of the 13 recognized flow units. (author)

  16. Geology and petrography in basaltic rocks (Arapey formation) cropping out in road 30 between the Bella Union round point (27 km) and Penas cuesta (225 Km)

    International Nuclear Information System (INIS)

    Oyhantcabal, P.; Pineiro, G.


    This contribution presents a geological map of the basaltic flows of Arapey formation (Mezosoic) cropping out in Road 30 between the Bella Union round point (27 Km) and Pena s cuesta (225 Km) together with the description of the petrographic features of the different portions of the 20 recognized flow units

  17. Soft-sediment ichnotaxa from the Cenozoic White Limestone Group, Jamaica, West Indies

    NARCIS (Netherlands)

    Blissett, D.J.; Pickerill, R.K.


    Jamaica, the third largest of the Greater Antillean islands, exposes various lithological units that are dominated by Cenozoic carbonate rocks including those of the mid-Cenozoic White Limestone Group. This Group is comprised of six formations, the Troy, Swanswick, Somerset, Moneague, Montpelier and

  18. Mid-crust fluid and water-rock interaction kinetic experiments and their geophysical significance: 1. Basalt and pyroxene in water at high temperatures up to 450°C (United States)

    Zhang, R.; Zhang, X.; Hu, S.


    The water-basaltic rock interaction (or pyroxene-water ) kinetic experiments are carried out using flow through a packed bed reactor (PBR) and a mixed flow reactor(MFR) in the temperature range(T) from 20 to 450°C and at 23-34MPa. The experimental apparatus consisted of a titanium vessel, a liquid pump, a backpressure regulator, an electrical conductivity detector and a computer for data acquisition and monitoring. The basaltic rock and pyroxene were collected from natural volcanic area, Anhui Province, China. Rock or mineral sample was crushed and sieved to 20-40 mesh and cleaned. The surface area of representative basalt samples is 9.978 m2/g, for pyroxene it is 1.987 m2 /g (BET method). As using PBR system, rock samples (10. 2526g) were placed in the vessel. De-ionized and degassed (DDW) water was passed through the rock, or mineral grains at flow rates of 0.5-8 ml/min. As using MFR system mineral and rock sample of 5 grams was put in the vessel. Here, the measured release rates for each metal of the rock are the sum of release rates of the metal in various minerals of the rock. Steady-state kinetics is defined as conditions where dissolution rates are time independent. For water-basalt interaction, the dissolution rates (dis.r.) of Ca, Mg, Fe, Al, Na, K and Si vary with T from 25 to 435°C(or to 550°C). The dis.r. of Si, rSi increase with T from 25°C to 300°C, and then decrease from 300°C to 435°C (to 550°C). Maximum dis.r. for Si, rSi, Mx is reached at 300°C(or 300 to 400°C, using MFR). The maximum dis.r. for various metals occurred at different T, e.g. rAl, Mx and rNa, Mx are nearly at 350°C, rK, Mx is at 300°C, rCa, Mx is at 100°C and rMg, Mx is at 20°C. As T increase above 400°C, dis.r. of Ca, Mg and Fe decrease to very small. The experiments for pyroxene (diopside, hedenbergite)in water indicated that the dis.r. of Ca, Mg, Fe, Al, K and Si also vary with T. The rSi increase with T from 25 to 300°C, and then decrease with T from 300 to 400

  19. Flood basalts and extinction events (United States)

    Stothers, Richard B.


    The largest known effusive eruptions during the Cenozoic and Mesozoic Eras, the voluminous flood basalts, have long been suspected as being associated with major extinctions of biotic species. Despite the possible errors attached to the dates in both time series of events, the significance level of the suspected correlation is found here to be 1 percent to 4 percent. Statistically, extinctions lag eruptions by a mean time interval that is indistinguishable from zero, being much less than the average residual derived from the correlation analysis. Oceanic flood basalts, however, must have had a different biological impact, which is still uncertain owing to the small number of known examples and differing physical factors. Although not all continental flood basalts can have produced major extinction events, the noncorrelating eruptions may have led to smaller marine extinction events that terminated at least some of the less catastrophically ending geologic stages. Consequently, the 26 Myr quasi-periodicity seen in major marine extinctions may be only a sampling effect, rather than a manifestation of underlying periodicity.

  20. Lu-Hf constraints on the evolution of lunar basalts

    International Nuclear Information System (INIS)

    Fujimaki, H.; Tatsumoto, M.


    Very low Ti basalts andd green glass samples from the moon show high Lu/Hf ratios and low Hf concentrations. Low-Ti lunar basalts show high and variable Lu/Hf ratios and higher Hf concentrations, whereas high-Ti lunar basalts show low Lu/Hf ratios and high Hf concentrations. KREEP basalts have constant Lu/Hf ratios and high but variable Hf concentrations. Using the Lu-Hf behavior as a constraint, we propose a model for the mare basalts evolution. This constraint requires extensive crystallization of the primary lunar magma ocean prior to formation of the lunar mare basalt sources and the KREEP basalts. Mare basalts are produced by the melting of the cumulate rocks, and KREEP basalts represent the residual liquid of the magma ocean

  1. Basalts and picrites from a plume-type ophiolite in the South Qilian Accretionary Belt, Qilian Orogen: Accretion of a Cambrian Oceanic Plateau? (United States)

    Zhang, Yuqi; Song, Shuguang; Yang, Liming; Su, Li; Niu, Yaoling; Allen, Mark B.; Xu, Xin


    Oceanic plateaus with high-Mg rocks in the present-day oceanic crust have attracted much attention for their proposed mantle-plume origins and abnormally high mantle potential temperatures (Tp). However, equivalent rocks in ancient oceanic environments are usually poorly preserved because of deformation and metamorphism. Here we present petrological, geochronological and geochemical data for pillow lavas from Cambrian ophiolites in the Lajishan and Yongjing regions of the South Qilian Accretionary Belt (SQAB), from the southern part of the Qilian Orogen, northern China. Three rock groups can be identified geochemically: (1) sub-alkaline basalts with enriched mid- ocean ridge basalt (E-MORB) affinity; (2) alkaline basalts with oceanic island basalt (OIB) features, probably derived from partial melting of an enriched mantle source; and (3) picrites with MgO (18-22 wt%). Cr-numbers [Cr# = Cr/(Cr + Al)] of spinels from the picrites suggest 18-21% degree of partial melting at the estimated mantle potential temperature (Tp) of 1489-1600 °C, equivalent to values of Cenozoic Hawaiian picrites (1500-1600 °C). Zircons from one gabbro sample yielded a U-Pb Concordia age of 525 ± 3 Ma, suggesting the oceanic crust formed in the Cambrian. Available evidence suggests that Cambrian mantle plume activity is preserved in the South Qilian Accretionary Belt, and influenced the regional tectonics: "jamming" of the trench by thick oceanic crust explains the emplacement and preservation of the oceanic plateau, and gave rise to the generation of concomitant Ordovician inner-oceanic island arc basalts via re-organisation of the subduction zones in the region.

  2. Geochemistry of ultramafic xenoliths in Cenozoic alkali basalts from ...

    Indian Academy of Sciences (India)

    The P–T conditions suggest that the geothermal gradient of the upper mantle beneath the study area is approximately similar to oceanic geotherm which may be caused by asthenosphere upwelling. We suggested that lithospheric mantle thinning accompanied by asthenosphere upwelling has occurred and a newly ...

  3. Geochemistry of ultramafic xenoliths in Cenozoic alkali basalts from ...

    Indian Academy of Sciences (India)

    Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan. Department of Tourism, Aletheia University, Tamsui 25103, Taiwan. National Museum of Natural Science, Taichung 404, Taiwan. Sinotech Engineering Consultants Inc., Taipei 114, Taiwan. Department of Leisure Business Management, DeLin ...

  4. Interaction of extended mantle plume head with ancient lithosphere: evidence from deep-seated xenoliths in basalts and lamprophyre diatremes in Western Syria (United States)

    Sharkov, Evgenii


    The Middle Cretaceous lamprophyric diatremes of the Jabel Ansaria Ridge contain xenoliths of ancient lower crustal rocks mainly represented by the suite of partly altered garnet granulite and eclogite-like rocks, which were formed at the expense of ferrogabbros and ferroclinopyroxenites most likely in the course of underplating of Fe-Ti basalt. Garnet (Alm26Grs11Py63) megacrysts and coarse-granular garnet-clinopyroxene intergrowths are most likely the varieties of rocks of this series. Garnet megacrysts are represented by large (up to 10 cm in diameter) round "nodules," often molten from the surface. Garnet is usually fractured, and the kelyphite material similar to that in rocks of the eclogite-granulite series occurs in fractures. In addition, we found several intergrowths of garnet with large (up to 3-5 cm in length) crystals of high-Al augite with the low of Ti and Na contents like in rocks of the eclogite-granulite suite. Coarse-grained garnet-clinopyroxene-hornblende rocks with spinel, as well as megacrysts of Al-Ti augite with kaersutite, form the second group in prevalence. This group is close to mantle xenoliths of the "black series" in alkali Fe-Ti basalt worldwide. Kaersutite in these rocks contains gaseous cavities, which provides evidence for the origin of rocks at the expense of a strongly fluidized melt/fluid. In contrast to rocks of the eclogite-granulite series, these rocks did not undergo alteration. Garnet Alm19-26Grs12-13.5Py59-67.5 usually associates with dark opaque spinel. In contrast, the Late Cenozoic plateaubasalts of the region practically do not contain lower crustal xenoliths, whereas xenoliths of mantle spinel lherzolite (fragments of the upper cooled rim of the plume head) are widely abundant. According to data of mineralogical thermobarometry, rocks of the eclogite-granulite suite were formed at 13.5-15.4 kbar (depths of 45-54 km) and 965-1115°C. Rocks of this suite are typical representatives of the continental lower crust

  5. The genesis and evolution of Hannuoba Basalt based on the Xiaomaping basalt profile (United States)

    Huixin, Hei; Shangguo, Su; Yu, Wang


    Hannuoba basalt lies in the northern of North China. It erupted in Cenozoic with well outcrops and widespread ultramafic xenoliths. This study focuses on the Xiaomaping basalt profile in Hannuoba district. The profile can be distinguished for 7 layers with each bottom of the layer enriched with ultramafic xenoliths. In the Hark polt, all major elements have good correlation with the MgO content, showing the basalt from different layers having an consistent evolution. The phenocrysts in the basalt from different layers are rare and mostly within 5% with main faces as Ol, Cpx and Opx. The chemical characteristic of the basalt shows mutative features, Mg# (52.0-67.7), CaO (7.3-8.5wt. %), Ni (82-192ppm) and Cr (65-192ppm). The basalts have apparent LREE enrichment and are rich in HFSE (Nb,Ta,Zr) and in LILE (Ba, Sr). All the basalt layers do not show manifest negative Eu with δEu=1.01-1.05. The ultramafic xenoliths are spinel-lherzolite, with weak lack of LREE. Trace element ratios, Ba / Rb and Rb / Sr, show that the source might have experienced some extent of fluid metasomatism. According to the La and La/Sm plot, the basalts are mainly controlled by the partial melting, and the great extent of fractional crystallization did not happened during the evolution process. Based on current published experimental results and theoretical petrology analysis, Hannuoba basalts formed in equilibrium with pyroxenite with clinopyroxene and garnet as the main mineral faces in the source and accounting olivine in small extent.

  6. Basaltic cannibalism at Thrihnukagigur volcano, Iceland (United States)

    Hudak, M. R.; Feineman, M. D.; La Femina, P. C.; Geirsson, H.


    Magmatic assimilation of felsic continental crust is a well-documented, relatively common phenomenon. The extent to which basaltic crust is assimilated by magmas, on the other hand, is not well known. Basaltic cannibalism, or the wholesale incorporation of basaltic crustal material into a basaltic magma, is thought to be uncommon because basalt requires more energy than higher silica rocks to melt. Basaltic materials that are unconsolidated, poorly crystalline, or palagonitized may be more easily ingested than fully crystallized massive basalt, thus allowing basaltic cannibalism to occur. Thrihnukagigur volcano, SW Iceland, offers a unique exposure of a buried cinder cone within its evacuated conduit, 100 m below the main vent. The unconsolidated tephra is cross-cut by a NNE-trending dike, which runs across the ceiling of this cave to a vent that produced lava and tephra during the ~4 Ka fissure eruption. Preliminary petrographic and laser ablation inductively coupled mass spectrometry (LA-ICP-MS) analyses indicate that there are two populations of plagioclase present in the system - Population One is stubby (aspect ratio 2.1), subhedral to euhedral, and has much higher Ba/Sr ratios. Population One crystals are observed in the cinder cone, dike, and surface lavas, whereas Population Two crystals are observed only in the dike and surface lavas. This suggests that a magma crystallizing a single elongate population of plagioclase intruded the cinder cone and rapidly assimilated the tephra, incorporating the stubbier population of phenocrysts. This conceptual model for basaltic cannibalism is supported by field observations of large-scale erosion upward into the tephra, which is coated by magma flow-back indicating that magma was involved in the thermal etching. While the unique exposure at Thrihnukagigur makes it an exceptional place to investigate basaltic cannibalism, we suggest that it is not limited to this volcanic system. Rather it is a process that likely

  7. Study of rock-water-nuclear waste interactions in the Pasco Basin, Washington: Part II. Preliminary equilibrium-step simulations of basalt diagenesis

    International Nuclear Information System (INIS)

    Benson, L.V.; Carnahan, C.L.; Che, M.


    Interactions between a large number of complex chemical and physical processes have resulted in significant changes in the Pasco Basin hydrochemical system since emplacement of the first basalt flow. In order to perform preliminary simulations of the chemical evolution of this system, certain simplifying assumptions and procedures were adopted and a computer model which operates on the principal of local equilibrium was used for the mass transfer calculations. Significant uncertainties exist in both the thermodynamic and reaction rate data which were input to the computer model. In addition, the compositional characteristics of the evolving hydrochemical system remain largely unknown, especially as a function of distance along the flow path. Given these uncertainties, it remains difficult to assess the applicability of the equilibrium-step approach even though reasonable matches between observed and simulated hydrochemical data were obtained. Given the uncertainties mentioned, the predictive abilities of EQ6 are difficult, if not impossible to evaluate; our simulations produced, at best, only qualitative agreement with observed product mineral assemblages and sequences, and fluid compositions

  8. Effects of Basalt Fibres on Mechanical Properties of Concrete

    Directory of Open Access Journals (Sweden)

    El-Gelani A. M.


    Full Text Available This paper presents the results of an experimental program carried out to investigate the effects of Basalt Fibre Reinforced Polymers (BFRP on some fundamental mechanical properties of concrete. Basalt fibres are formed by heating crushed basalt rocks and funnelling the molten basalt through a spinneret to form basalt filaments. This type of fibres have not been widely used till recently. Two commercially available chopped basalt fibres products with different aspect ratios were investigated, which are dry basalt (GeoTech Fibre and basalt pre-soaked in an epoxy resin (GeoTech Matrix .The experimental work included compression tests on 96 cylinders made of multiple batches of concrete with varying amounts of basalt fibre additives of the two mentioned types, along with control batches containing no fibres. Furthermore, flexural tests on 24 prisms were carries out to measure the modulus of rupture, in addition to 30 prisms for average residual strength test. Results of the research indicated that use of basalt fibres has insignificant effects on compressive strength of plain concrete, where the increase in strength did not exceed about 5%. On the other hand, results suggest that the use of basalt fibres may increase the compressive strength of concrete containing fly as up top 40%. The rupture strength was increased also by 8% to 28% depending on mix and fibre types and contents. Finally, there was no clear correlation between the average residual strength and ratios of basalt fibres mixed with the different concrete batches.

  9. Evaluating Handheld X-Ray Fluorescence (XRF) Technology in Planetary Exploration: Demonstrating Instrument Stability and Understanding Analytical Constraints and Limits for Basaltic Rocks (United States)

    Young, K. E.; Hodges, K. V.; Evans, C. A.


    While large-footprint X-ray fluorescence (XRF) instruments are reliable providers of elemental information about geologic samples, handheld XRF instruments are currently being developed that enable the collection of geochemical data in the field in short time periods (approx.60 seconds) [1]. These detectors are lightweight (1.3kg) and can provide elemental abundances of major rock forming elements heavier than Na. While handheld XRF detectors were originally developed for use in mining, we are working with commercially available instruments as prototypes to explore how portable XRF technology may enable planetary field science [2,3,4]. If an astronaut or robotic explorer visited another planetary surface, the ability to obtain and evaluate geochemical data in real-time would be invaluable, especially in the high-grading of samples to determine which should be returned to Earth. We present our results on the evaluation of handheld XRF technology as a geochemical tool in the context of planetary exploration.

  10. Rapid solubility and mineral storage of CO2 in basalt

    DEFF Research Database (Denmark)

    Gislason, Sigurdur R.; Broecker, W.S.; Gunnlaugsson, E.


    rich in divalent metal cations such as basalts and ultra-mafic rocks. We have demonstrated the dissolution of CO2 into water during its injection into basalt leading to its geologic solubility storage in less than five minutes and potential geologic mineral storage within few years after injection [1...

  11. Volcano-sedimentary characteristics in the Abu Treifiya Basin, Cairo-Suez District, Egypt: Example of dynamics and fluidization over sedimentary and volcaniclastic beds by emplacement of syn-volcanic basaltic rocks (United States)

    Khalaf, E. A.; Abdel Motelib, A.; Hammed, M. S.; El Manawi, A. H.


    This paper describes the Neogene lava-sediment mingling from the Abu Treifiya Basin, Cairo-Suez district, Egypt. The lava-sediment interactions as peperites have been identified for the first time at the study area and can be used as paleoenvironmental indicators. The identification of peperite reflects contemporaneous time relationship between volcanism and sedimentation and this finding is of primary importance to address the evolutional reconstruction of the Abu Treifiya Basin. Characterization of the facies architecture and textural framework of peperites was carried out through detailed description and interpretation of their outcrops. The peperites and sedimentary rocks are up to 350 m thick and form a distinct stratigraphic framework of diverse lithology that is widespread over several kilometers at the study area. Lateral and vertical facies of the peperites vary from sediment intercalated with the extrusive/intrusive basaltic rocks forming peperitic breccias to lava-sediment contacts at a large to small scales, respectively. Peperites encompass five main facies types ascribed to: (i) carbonate sediments-hosted fluidal and blocky peperites, (ii) lava flow-hosted blocky peperites, (iii) volcaniclastics-hosted fluidal and blocky peperites, (iv) sandstone/siltstone rocks-hosted blocky peperites, and (iv) debris-flows-hosted blocky peperites. Soft sediment deformation structures, vesiculated sediments, sediments filled-vesicles, and fractures in lava flows indicate that lava flows mingled with unconsolidated wet sediments. All the peperites in this study could be described as blocky or fluidal, but mixtures of different clast shapes occur regardless of the host sediment. The presence of fluidal and blocky juvenile clasts elucidates different eruptive styles, reflecting a ductile and brittle fragmentation. The gradual variation from fluidal to blocky peperite texture, producing the vertical grading is affected by influencing factors, e.g., the viscosity, magma

  12. Convergent Cenozoic CO2 history (United States)

    Royer, D. L.; Beerling, D. J.


    The quality and quantity of Cenozoic CO2 records have increased significantly in the last decade. Gains in quality have come primarily from a fuller accounting of confounding factors; examples include soil respiration rates in the pedogenic carbonate method, alkalinity and seawater δ11B in the boron method, and cell size in the alkenone phytoplankton method. Previously, variability across Cenozoic CO2 estimates in a given time period sometimes exceeded an order of magnitude, but through these improvements variability has been reduced to a factor of two or less. Further improvements in the record can probably be facilitated by more robust quantification of statistical error, generation of CO2 estimates at single locations from multiple methods, and cross-calibration with Pleistocene ice-core CO2 records (Beerling & Royer, 2011, Nature Geoscience 4: 418-420). An improved Cenozoic CO2 record offers opportunities for better understanding Earth system processes. We provide one example related to climate sensitivity. We find a significant relationship between CO2 radiative forcing and global temperature during the Cenozoic, even after accounting for forcings related to solar evolution and paleogeographic changes. Although the calculations are based on simple assumptions and should be taken as provisional, the mean Cenozoic climate sensitivity (3 °C or higher per CO2 doubling) is similar to or higher than calculations for the present-day (~3 °C per CO2 doubling).

  13. Stratigraphy and Folding in the Cenozoic Cover of a Fold-Thrust Belt in the Nallıhan Region (Ankara, Central Turkey) (United States)

    Karaaǧaç, Serdal; Koral, Hayrettin


    This study investigates stratigraphy and structural features in the Cenozoic sedimentary sequence of the fold-thrust belt of the Nallıhan-Ankara region, located to the north of the İzmir-Ankara-Erzincan Suture Zone. Permian-Triassic age marble intercalated with schist-phyllites, the upper Jurassic-lower Cretaceous age limestone and the upper Cretaceous age sandstone-shale alternation compose the basement in the study area. These rocks are unconformably overlain by the Cenozoic age terrestrial sedimentary and volcanic units. The Cenozoic stratigraphy begins with the Paleocene-Eocene age coal-bearing, at times, volcanic intercalated conglomerate-sandstone-mudstone alternation of alluvial-fluvial origins (Aksaklar Formation) and the tuff intercalated with lacustrine limestone, bituminous limestone (Kabalar Formation). These units are conformably overlain by the Eocene age basalt-andesite and pyroclastic rocks (Meyildere volcanics). The Paleocene-Eocene aged units are unconformably overlain by the conglomerate-sandstone-mudstone-marl of a lower-middle Miocene lacustrine environment (Hançili Formation). The terrestrial conglomerate-sandstone alternation (Örencik Formation) is the youngest unit in the Cenozoic stratigraphy, and is assumed to be of Pliocene age based its stratigraphic position on older units. Field study shows existence of both folds and faults in the sedimentary cover. Stereographic projections of bedding measured in the field shows N25W/45NW and N60W/4SE-oriented fold axes in the Paleocene-Eocene age units. There are also N76W/12SE and N88E/8NE-oriented folds. The difference in fold-axis orientations suggests that some folds may have been rotated in blocks bound by faults during the post-Paleocene/Eocene period. Whereas, the lower-middle Miocene units manifest N88W/13SE-oriented fold axes. It is thus proposed that the observed difference in the azimuth of fold axes represent two different folding phases, one with NE-SW and the other with N

  14. Can we identify source lithology of basalt? (United States)

    Yang, Zong-Feng; Zhou, Jun-Hong


    The nature of source rocks of basaltic magmas plays a fundamental role in understanding the composition, structure and evolution of the solid earth. However, identification of source lithology of basalts remains uncertainty. Using a parameterization of multi-decadal melting experiments on a variety of peridotite and pyroxenite, we show here that a parameter called FC3MS value (FeO/CaO-3*MgO/SiO2, all in wt%) can identify most pyroxenite-derived basalts. The continental oceanic island basalt-like volcanic rocks (MgO>7.5%) (C-OIB) in eastern China and Mongolia are too high in the FC3MS value to be derived from peridotite source. The majority of the C-OIB in phase diagrams are equilibrium with garnet and clinopyroxene, indicating that garnet pyroxenite is the dominant source lithology. Our results demonstrate that many reputed evolved low magnesian C-OIBs in fact represent primary pyroxenite melts, suggesting that many previous geological and petrological interpretations of basalts based on the single peridotite model need to be reconsidered.

  15. Hydrothermal evolution of repository groundwaters in basalt

    International Nuclear Information System (INIS)

    Apps, J.A.


    Groundwaters in the near field of a radioactive waste repository in basalt will change their chemical composition in response to reactions with the basalt. These reactions will be promoted by the heat generated by the decaying waste. It is important to predict both the rate and the extent of these reactions, and the secondary minerals produced, because the alteration process controls the chemical environment affecting the corrosion of the canister, the solubility and complexation of migrating radionuclides, the reactivity of the alteration products to radionuclides sorption, and the porosity and permeability of the host rock. A comprehensive review of the literature leads to the preliminary finding that hydrothermally altering basalts in geothermal regions such as Iceland lead to a secondary mineralogy and groundwater composition similar to that expected to surround a repository. Furthermore, laboratory experiments replicating the alteration conditions approximate those observed in the field and expected in a repository. Preliminary estimates were made of the rate of hydration and devitrification of basaltic glass and the zero-order dissolution rate of basaltic materials. The rates were compared with those for rhyolitic glasses and silicate minerals. Preliminary calculations made of mixed process alteration kinetics, involving pore diffusion and surface reaction suggest that at temperatures greater than 150 0 C, alteration proceeds so rapidly as to become pervasive in normally fractured basalt exposed to higher temperatures in the field. 70 references

  16. Naming Lunar Mare Basalts: Quo Vadimus Redux (United States)

    Ryder, G.


    Nearly a decade ago, I noted that the nomenclature of lunar mare basalts was inconsistent, complicated, and arcane. I suggested that this reflected both the limitations of our understanding of the basalts, and the piecemeal progression made in lunar science by the nature of the Apollo missions. Although the word "classification" is commonly attached to various schemes of mare basalt nomenclature, there is still no classification of mare basalts that has any fundamental grounding. We remain basically at a classification of the first kind in the terms of Shand; that is, things have names. Quoting John Stuart Mill, Shand discussed classification of the second kind: "The ends of scientific classification are best answered when the objects are formed into groups respecting which a greater number of propositions can be made, and those propositions more important than could be made respecting any other groups into which the same things could be distributed." Here I repeat some of the main contents of my discussion from a decade ago, and add a further discussion based on events of the last decade. A necessary first step of sample studies that aims to understand lunar mare basalt processes is to associate samples with one another as members of the same igneous event, such as a single eruption lava flow, or differentiation event. This has been fairly successful, and discrete suites have been identified at all mare sites, members that are eruptively related to each other but not to members of other suites. These eruptive members have been given site-specific labels, e.g., Luna24 VLT, Apollo 11 hi-K, A12 olivine basalts, and Apollo 15 Green Glass C. This is classification of the first kind, but is not a useful classification of any other kind. At a minimum, a classification is inclusive (all objects have a place) and exclusive (all objects have only one place). The answer to "How should rocks be classified?" is far from trivial, for it demands a fundamental choice about nature

  17. Experimental alterations on ceramic interest basalts

    International Nuclear Information System (INIS)

    Sanfeliu-Montolio, T.; Ballbe-Lonch, E.; Querlat-Mitjans, I.; Juan-Abril, A.; Fuente-Cellell, C. de la


    This study presents the results and conclusion extracted of the chemical and mineralogical analysis made on 12 samples of recent and subrecent (IV series) Canary Island's basalt, that have been subject to different attack processes in order to cause in them controlled mineralogical alterations. The methods used were: optical analysis, x-ray fluorescence analysis and x-ray diffraction. The object of this work is to determine the alterability of these basaltic rocks that have ceramic interest since it's possible its use in same ceramic manufactures and also as petrurgic raw material. (author)

  18. Vapor deposition in basaltic stalactites, Kilauea, Hawaii (United States)

    Baird, A. K.; Mohrig, D. C.; Welday, E. E.

    Basaltic stalacties suspended from the ceiling of a large lava tube at Kilauea, Hawaii, have totally enclosed vesicles whose walls are covered with euhedral FeTi oxide and silicate crystals. The walls of the vesicles and the exterior surfaces of stalactites are Fe and Ti enriched and Si depleted compared to common basalt. Minerals in vesicles have surface ornamentations on crystal faces which include alkali-enriched, aluminosilicate glass(?) hemispheres. No sulfide-, chloride-, fluoride-, phosphate- or carbonate-bearing minerals are present. Minerals in the stalactites must have formed by deposition from an iron oxide-rich vapor phase produced by the partial melting and vaporization of wall rocks in the tube.

  19. Thermoluminescence dating of Hawaiian basalt (United States)

    May, Rodd James


    The thermoluminescence (TL) properties of plagioclase separates from 11 independently dated alkalic basalts 4,500 years to 3.3 million years old and 17 tholeiitic basalts 16 years to 450,000 years old from the Hawaiian Islands were investigated for the purpose of developing a TL dating method for young volcanic rocks. Ratios of natural to artificial TL intensity, when normalized for natural radiation dose rates, were used to quantify the thermoluminescence response of individual samples for age-determination purposes. The TL ratios for the alkalic basalt plagioclase were found to increase with age at a predictable exponential rate that permits the use of the equation for the best-fit line through a plot of the TL ratios relative to known age as a TL age equation. The equation is applicable to rocks ranging in composition from basaltic andesite to trachyte over the age range from about 2,000 to at least 250,000 years before present (B.P.). The TL ages for samples older than 50,000 years have a calculated precision of less than :t 10 percent and a potential estimated accuracy relative to potassium-argon ages of approximately :t 10 percent. An attempt to develop a similar dating curve for the tholeiitic basalts was not as successful, primarily because the dose rates are on the average lower than those for the alkalic basalts by a factor of 6, resulting in lower TL intensities in the tholeiitic basalts for samples of equivalent age, and also because the age distribution of dated material is inadequate. The basic TL properties of the plagioclase from the two rock types are similar, however, and TL dating of tholeiitic basalts should eventually be feasible over the age range 10,000 to at least 200,000 years B.P. The average composition of the plagioclase separates from the alkalic basalts ranges from oligoclase to andesine; compositional variations within this range have no apparent effect on the TL ratios. The average composition of the plagioclase from the tholeiitic

  20. Post-Columbia River Basalt Group stratigraphy and map compilation of the Columbia Plateau, Oregon

    International Nuclear Information System (INIS)

    Farooqui, S.M.; Bunker, R.C.; Thoms, R.E.; Clayton, D.C.; Bela, J.L.


    This report presents the results of reconnaissance mapping of sedimentary deposits and volcanic rocks overlying the Columbia River Basalt. The project area covers parts of the Dalles, Pendleton, Grangeville, Baker, Canyon City, and Bend. The mapping was done to provide stratigraphic data on the sedimentary deposits and volcanic rocks overlying the Columbia River Basalt Group. 160 refs., 16 figs., 1 tab

  1. Geochemical study of young basalts in East Azerbaijan (Northwest of Iran

    Directory of Open Access Journals (Sweden)

    Nasir Amel


    Full Text Available The young basalts in East Azerbaijan are placed in West Alborz – Azerbaijan zone. Volcanic activities have extended from the Pliocene to the Quaternary by eruption from fracture systems and faults. Rocks under study are olivine-basalt and trachybasalts. The main minerals are olivine, pyroxene, plagioclase set in glassy or microcrystalline matrix and olivine are present as phenocryst. The textures in the studied rocks are mainly hyaloporphyric, hyalomicrolitic and porphyritic. Trace elements and rare earth elements on spider diagrams have high LREE/HREE ratio. Rare earth elements on diagram display negative slope indicating alkaline nature for the basalts under study. As it may be observed, on tectonic diagrams, the Marand basalts are placed on Island Arc basalt (IAB field, whereas the Ahar, Heris, Kalaibar and Miyaneh basalts are classified as Ocean Island Basalts (OIB and finally the basalts of Sohrol area are plotted on continental rift Basalt (CRB field. The Marand and Sohrol basalts were likely originated from lithospheric - astenospheric mantle with 2 to 5 % partial melting whereas, the Ahar, Heris and Kalaibar basalts having same source experienced 1-2% partial melting rate and the Miyaneh basalts possibly produced from lithospheric mantle with 10-20% partial melting rate pointing to shallow depth of mantle and the higher rate of melting. Based on tectonic setting diagrams, all the rocks studied are plotted in post collisional environments.

  2. Influence of basalt/groundwater interactions on radionuclide migration

    International Nuclear Information System (INIS)

    Vandegrift, G.F.


    The work presented here is a partial summary of the experimental results obtained in the Laboratory Analog Program. Two aspects of this effort are (1) the interaction between simulated basaltic groundwater and basalt fissures that were either freshly cleaved or laboratory altered by hydrothermal treatment with the simulated groundwater and (2) the effect of this interaction on radionuclide migration through these basalt fissures. The following conclusions of this study bear heavily on the predicted safety of a basalt repository: Sorption properties of freshly fissured basalt and naturally aged basalt are quite different for different chemical species. Analog experiments predict that aged basalt would be an effective retarder of cesium, but would be much less so for actinide elements. Distribution ratios measured from batch experiments with finely ground rock samples (presenting unaltered rock surfaces) are not a reliable means of predicting radionuclide migration in geological repositories. As the near-repository area is resaturated by groundwater, its ability to retard actinide migration will be degraded with time. Disturbing the natural flow of groundwater through the repository area by constructing and backfilling the repository will modify the composition of groundwater. This modified groundwater is likely to interact with and to modify naturally aged basalt surfaces downstream from the repository

  3. Sr, Nd and Pb Isotope Systematics of the Cenozoic Volcanism in the Algerian Tell Belt: a Key Constraint on the Geodynamic Evolution of the Westernmost Mediterranean (United States)

    Meddi, Yassamina; Garrido, Carlos J.; Marchesi, Claudio; Louni-Hacini, Amina; Azzouni-Sekkal, Abla; Varas Reus, María Isabel; Harvey, Jason; Hidas, Károly


    The geodynamic evolution of the Western Mediterranean is closely linked to the spatio-temporal evolution of the Cenozoic magmatism in this region. Here, we present a detailed Sr-Nd-Pb study of Cenozoic volcanism from the external and the internal zones of the Algerian Tell belt, a segment of paramount importance to unravel the Alpine geodynamic evolution of the westernmost Mediterranean. The age of the studied volcanics rocks ranges from 17 to 3 Ma, and covers the temporal and spatial evolution of magmatism from calc-alkaline rocks with a clear signature of subduction (commonly referred as to orogenic magmatism), followed by progressively younger sub-alkaline and alkaline volcanism. On the basis of their major and trace element composition, the Tell Cenozoic volcanic rocks can be classified into three main groups: (1) a Si-poor group that is composed of basalt, trachybasalt and basaltic trachyandesite; (2) a Si-intermediate group —raging in silica from 56 to 66 wt. %— that is composed of andesite, dacite, trachyandesite et trachydacite; and a (3) Si-rich group —with silica contents generally greater than 66 wt.%— that is constituted by trachydacite, dacite and rhyolite. The Si-poor group occurs only in the External zone and it is characterized by non-radiogenic 87Sr/86Sr ratios, high initial 144Nd/143Nd ratios, significant variation of 206Pb/204Pb and 207Pb/204Pb ratios, and relatively constant 208Pb/204Pb ratios. The Si-intermediate and Si-rich groups from the Internal and External zones show substantial differences. The 206Pb/204Pb ratios of External zone volcanism are relatively constants [18.68-18.86], while they vary significantly in the Internal zone volcanism [18.55-18.92]. On the other hand, the initial 207Pb/204Pb and 208Pb/204Pb ratios in Internal zone volcanism [38.81-38.95] are significantly higher than those of the External zone [38.68-38.84]. These differing isotopic signatures reflect variable source contamination by subducted sediments

  4. Analysing the Cenozoic depositional record

    DEFF Research Database (Denmark)

    Goledowski, Bartosz; Clausen, O.R.; Nielsen, S.B.


    between the global climate record (oxygen isotopes) and lithology variations on the Eocene-Oligocene transition in the eastern North Sea. Due to the strongly limited time resolution of low temperature thermochronology, the Cenozoic sedimentary record potentially provides the most detailed history...... models. The matrix mass deposition history will be compared with the paleoclimate record (e.g. oxygen isotope curves) to see if the previously observed correlation in the eastern North Sea can be extended to other ages and locations.  ...

  5. Geochemistry, age and strontium isotope composition of late tertiary and quaternary basalts and andesites in western Nevada and their relation to geothermal potential. Final report, October 1, 1982-December 31, 1983

    Energy Technology Data Exchange (ETDEWEB)

    Fultz, L.A.; Bell, E.J.; Trexler, D.T.


    This research was undertaken to characterize the late Cenozoic volcanic rocks associated with active geothermal systems in west-central Nevada. Petrographic and microprobe, geochemical and isotopic analysis and age dating techniques were used to characterize these young volcanic rocks. These data were combined with the limited data previously reported in the literature on these same volcanic areas to interpret their petrogenesis. The overall characterization resulted from integrating the petrogenesis with a structural-tectonic model of the region. Potassium-argon isotopic ages ranging up to 14 million years were determined for eight localities within the Reno 1 x 2/sup 0/ study region. These ages are consistent with the morphology of the volcanic landforms, the active geothermal systems associated with them, and with other isotopic ages reported in the literature for these and similar rocks within the study region. Petrographic analysis of hand specimens and thin-sections indicated mineralogic assemblages of the respective rock types and specific mineral textures and phenocryst compositions and characteristics. These identifications were further substantiated by microprobe analysis of selected phenocrysts and groundmass phases. Classification of the respective rock types was also based on chemical composition and normative calculations using the program PETCAL. Basaltic andesites are identified and described for Steamboat Hills, Table Mountain, Silver Springs, Churchill Butte, Cleaver Peak, Desert Peak and Carson City sites.

  6. Relating Cenozoic North Sea sediments to topography in southern Norway:

    DEFF Research Database (Denmark)

    Anell, Ingrid Anna Margareta; Thybo, Hans; Stratford, Wanda Rose


    sources for progradational influx of clastic sediments from Scotland, the Shetland platform and, to a lesser degree, southwestern Norway. The Eocene sedimentation pattern was similar to the Palaeocene, with lower rates of accumulation associated with flooding and tectonic quiescence. Sediment influx from...... the Shetland platform continued throughout the Cenozoic while supply from southern Norway increased markedly around the Eocene–Oligocene, coeval with the greenhouse–icehouse transition. Mass balance calculations of sediment and eroded rock volumes suggest that while some topography along the western margin...

  7. Submarine basaltic fountain eruptions in a back-arc basin during the opening of the Japan Sea (United States)

    Hosoi, Jun; Amano, Kazuo


    Basaltic rock generated during the middle Miocene opening of the Japan Sea, is widely distributed on the back-arc side of the Japanese archipelago. Few studies have investigated on submarine volcanism related to opening of the Japan Sea. The present study aimed to reconstruct details of the subaqueous volcanism that formed the back-arc basin basalts (BABB) during this event, and to discuss the relationship between volcanism and the tectonics of back-arc opening, using facies analyses based on field investigation. The study area of the southern Dewa Hills contains well-exposed basalt related to the opening of the Japan Sea. Five types of basaltic rock facies are recognized: (1) coherent basalt, (2) massive platy basalt, (3) jigsaw-fit monomictic basaltic breccia, (4) massive or stratified coarse monomictic basaltic breccia with fluidal clasts, and (5) massive or stratified fine monomictic basaltic breccia. The basaltic rocks are mainly hyaloclastite. Based on facies distributions, we infer that volcanism occurred along fissures developed mainly at the center of the study area. Given that the rocks contain many fluidal clasts, submarine lava fountaining is inferred to have been the dominant eruption style. The basaltic rocks are interpreted as the products of back-arc volcanism that occurred by tensional stress related to opening of the Japan Sea, which drove strong tectonic subsidence and active lava fountain volcanism.

  8. Calcites from Ocean Crust Basalts: Reliable Proxy Archives? (United States)

    Böhm, Florian; Eisenhauer, Anton


    Calcite cements in ocean crust basalts of the deep sea form from mixtures of cold seawater and warm hydrothermal fluids (about 0-70°C). These low temperature alteration (LTA) calcites have recently gained new interest as proxy recorders of seawater composition (Refs. 1-5). Recent LTA calcite reconstructions of the Sr/Ca and Mg/Ca evolution in ocean waters point to considerably lower Sr/Ca and Mg/Ca ratios during the Cretaceous and Paleogene than in the modern ocean. However, diagenetic alteration in contact with the basalt host rock may change the composition of the LTA calcites. For testing the reliability of LTA calcite records of seawater composition multi-proxy approaches are applied: oxygen isotopes indicate precipitation temperatures, strontium isotopes (87Sr/86Sr) and trace elements indicate influences from hydrothermal fluids. Additional information about the influence of basement rocks on LTA calcite composition can be derived from analyses of stable calcium and strontium isotopes (44/40Ca, 88/86Sr). We find low 44/40Ca values for DSDP and ODP sites where the 87Sr/86Sr ratios of LTA calcites indicate basement influence. On the other hand, for some sites the 87Sr/86Sr values inidicate precipitation from pristine seawater, while low 44/40Ca values indicate basement influence. All of these sites are either older than 50 Myr or show calcite precipitation temperatures >50°C. Sites that are younger than 25 Myr and had formation temperatures 50°C significantly higher 88/86Sr values were observed. The calcium isotope results indicate basement influence on LTA calcite composition at temperatures >10°C. Radiogenic strontium isotopes, in contrast, can be used as unequivocal basement influence indicators only at temperatures above 30°C. Below about 20°C 87Sr/86Sr ratios are no reliable indicators of basement influence. All LTA calcites of sites older than 50 Myr formed (or recrystallized) at temperatures >15°C. Low 44/40Ca values indicate that

  9. Basaltic volcanic episodes of the Yucca Mountain region

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.M.


    The purpose of this paper is to summarize briefly the distribution and geologic characteristics of basaltic volcanism in the Yucca Mountain region during the last 10--12 Ma. This interval largely postdates the major period of silicic volcanism and coincides with and postdates the timing of major extensional faulting in the region. Field and geochronologic data for the basaltic rocks define two distinct episodes. The patterns in the volume and spatial distribution of these basaltic volcanic episodes in the central and southern part of the SNVF are used as a basis for forecasting potential future volcanic activity in vicinity of Yucca Mountain. 33 refs., 2 figs.

  10. Sardinian basalt. An ancient georesource still en vougue (United States)

    Careddu, Nicola; Grillo, Silvana Maria


    Commercially quarried Sardinian basalt was the result of extensive volcanic activity during the Pliocene and Pleistocene ages, following the opening of the Campidano plain and Tyrrhenian sea rift. Extensive areas of Sardinia have been modelled by large volumes of basalt and andesite rock. An example is provided by the 'Giare' tablelands and other large plateaus located in central Sardinia. Other basalt-rich areas exist in the Island. Sardinia is featured by a vast array of basalt monuments, dating back to the II-I millennium BC, bearing witness to the great workability, durability and resistance to weathering of the rock. The complex of circular defensive towers, known as "Su Nuraxi di Barumini" was included in the World Heritage List by Unesco in 1997. Basalt is currently produced locally to be used for architectural and ornamental purposes. It is obtained by quarrying stone deposits or mining huge boulders which are moved and sawn by means of mechanical machinery. Stone-working is carried out in plants located in various sites of the Island. The paper begins with an historical introduction and then focusses on the current state of the art of Sardinian basalt quarrying, processing and using. An analysis of the basalt market has been carried out.

  11. Plate tectonics and continental basaltic geochemistry throughout Earth history (United States)

    Keller, Brenhin; Schoene, Blair


    Basaltic magmas constitute the primary mass flux from Earth's mantle to its crust, carrying information about the conditions of mantle melting through which they were generated. As such, changes in the average basaltic geochemistry through time reflect changes in underlying parameters such as mantle potential temperature and the geodynamic setting of mantle melting. However, sampling bias, preservation bias, and geological heterogeneity complicate the calculation of representative average compositions. Here we use weighted bootstrap resampling to minimize sampling bias over the heterogeneous rock record and obtain maximally representative average basaltic compositions through time. Over the approximately 4 Ga of the continental rock record, the average composition of preserved continental basalts has evolved along a generally continuous trajectory, with decreasing compatible element concentrations and increasing incompatible element concentrations, punctuated by a comparatively rapid transition in some variables such as La/Yb ratios and Zr, Nb, and Ti abundances approximately 2.5 Ga ago. Geochemical modeling of mantle melting systematics and trace element partitioning suggests that these observations can be explained by discontinuous changes in the mineralogy of mantle partial melting driven by a gradual decrease in mantle potential temperature, without appealing to any change in tectonic process. This interpretation is supported by the geochemical record of slab fluid input to continental basalts, which indicates no long-term change in the global proportion of arc versus non-arc basaltic magmatism at any time in the preserved rock record.

  12. The Ajo Mining District, Pima County, Arizona--Evidence for Middle Cenozoic Detachment Faulting, Plutonism, Volcanism, and Hydrothermal Alteration (United States)

    Cox, Dennis P.; Force, Eric R.; Wilkinson, William H.; More, Syver W.; Rivera, John S.; Wooden, Joseph L.


    Introduction: The Ajo porphyry copper deposit and surrounding Upper Cretaceous rocks have been separated from their plutonic source and rotated by detachment faulting. Overlying middle Cenozoic sedimentary and volcanic rocks have been tilted and show evidence for two periods of rotation. Following these rotations, a granitic stock (23.7?0.2 Ma) intruded basement rocks west of the Ajo deposit. This stock was uplifted 2.5 km to expose deep-seated Na-Ca alteration.

  13. Late Cenozoic Samtskhe-Javakheti Volcanic Highland, Georgia:The Result of Mantle Plumes Activity (United States)

    Okrostsvaridze, Avtandil


    Late Cenozoic Samtskhe-Javakheti continental volcanic highland (1500-2500 m a.s.l) is located in the SW part of the Lesser Caucasus. In Georgia the highland occupies more than 4500 km2, however its large part spreads towards the South over the territories of Turkey and Armenia. One can point out three stages of magmatic activity in this volcanic highland: 1. Early Pliocene activity (5.2-2.8 Ma; zircons U-Pb age) - when a large part of the highland was built up. It is formed from volcanic lava-breccias of andesite-dacitic composition, pyroclastic rocks and andesite-basalt lava flow. The evidences of this structure are: a large volume of volcanic material (>1500 km3); big thickness (700-1100 m in average), large-scale of lava flows (length 35 km, width 2.5-3.5 km, thickness 30-80 m), big thickness of volcanic ash horizons (300 cm at some places) and big size of volcanic breccias (diameter >1 m). Based on this data we assume that a source of this structure was a supervolcano (Okrostsvaridze et al., 2016); 2. Early Pleistocene activity (2.4 -1.6 Ma; zircons U-Pb age) - when continental flood basalts of 100-300 m thickness were formed. The flow is fully crystalline, coarse-grained, which mainly consist of olivine and basic labradorite. There 143Nd/144Nd parameter varies in the range of +0.41703 - +0.52304, and 87Sr/88Sr - from 0.7034 to 0.7039; 3. Late Pleistocene activity (0.35-0.021 Ma; zircons U-Pb age) - when intraplate Abul-Samsari linear volcanic ridge of andesite composition was formed stretching to the S-N direction for 40 km with the 8-12 km width and contains more than 20 volcanic edifices. To the South of the Abul-Samsari ridge the oldest (0.35-0.30 Ma; zircons U-Pb age) volcano Didi Abuli (3305 m a.s.l.) is located. To the North ages of volcano edifices gradually increase. Farther North the youngest volcano Tavkvetili (0.021-0. 030 Ma) is located (2583 m a.s.l.). One can see from this description that the Abul-Samsari ridge has all signs characterizing

  14. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Energy Technology Data Exchange (ETDEWEB)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yuan, Jianmin [College of Materials Engineering, Hunan University, Changsha, 410082 (China); Tan, Ligang [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082 (China); Wang, Shuangyin [State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Wu, Zhenjun, E-mail: [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China)


    Graphical abstract: - Highlights: • A new silane coupling agent was synthesized based on KH570. • Basalt surface was modified using the new silane coupling agent. • Chemical bond between basalt and the new silane coupling agent was formed. • Asphalt mixture which used modified basalt show superior water stability. - Abstract: A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  15. Continental flood basalts derived from the hydrous mantle transition zone. (United States)

    Wang, Xuan-Ce; Wilde, Simon A; Li, Qiu-Li; Yang, Ya-Nan


    It has previously been postulated that the Earth's hydrous mantle transition zone may play a key role in intraplate magmatism, but no confirmatory evidence has been reported. Here we demonstrate that hydrothermally altered subducted oceanic crust was involved in generating the late Cenozoic Chifeng continental flood basalts of East Asia. This study combines oxygen isotopes with conventional geochemistry to provide evidence for an origin in the hydrous mantle transition zone. These observations lead us to propose an alternative thermochemical model, whereby slab-triggered wet upwelling produces large volumes of melt that may rise from the hydrous mantle transition zone. This model explains the lack of pre-magmatic lithospheric extension or a hotspot track and also the arc-like signatures observed in some large-scale intracontinental magmas. Deep-Earth water cycling, linked to cold subduction, slab stagnation, wet mantle upwelling and assembly/breakup of supercontinents, can potentially account for the chemical diversity of many continental flood basalts.

  16. Late Mesozoic and Cenozoic thermotectonic history of the Mexican Pacific margin (18 to 25°N): new insight from apatite and zircon fission-track analysis of coastal and offshore plutonic rocks (United States)

    Calmus, Thierry; Poupeau, Gérard; Bourgois, Jacques; Michaud, François; Mercier de Lépinay, Bernard; Labrin, Erika; Azdimousa, Ali


    Apatite and zircon fission-track dating was used to constrain cooling histories on granitic samples taken from the offshore Acapulco trench batholith and onshore Manzanillo and Puerto Vallarta batholiths located along the southwestern active margin of Mexico, and from the La Paz batholith of southern Baja California. The apatite data indicate that many of the samples in the Manzanillo, Acapulco trench batholiths cooled rapidly below 60°C shortly after emplacement between 70 and 55 Ma. The La Paz batholith and the sample NM-20-08 of the Acapulco trench batholith experienced an older and slower cooling across the apatite partial annealing zone. The zircon fission-track ages obtained from two samples of the Puerto Vallarta batholith indicate a rapid cooling from 250 to 110°C between 54 and 50 Ma. This non-coeval cooling of batholiths at two different depths is probably due to uplift and erosion associated with the Laramide event in southwestern Mexico. The three samples from the Puerto Vallarta batholith suggest a younger evolution across low temperatures with two flat stages located near the base of the apatite partial annealing zone and above it. The first flat stage suggests that the denudation or rock uplift rate was reduced at a depth corresponding to the base of the apatite partial annealing zone. The younger single apatite ages of the Puerto Vallarta batholith, and the last common cooling of the other batholiths indicate the mild thermal influences of both the Plio-Pleistocene Trans-Mexican Volcanic Belt and the opening of the Gulf of California.

  17. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    in basalts from all the studied volcanic fields in Payenia is signs of lower crustal contamination indicating assimilation of, in some cases, large amounts of trace element depleted, mafic, plagioclase-bearing rocks. The northern Payenia is dominated by backarc basalts erupted between late Pliocene to late...... are isotopically similar to the Andean Southern Volcanic Zone arc rocks and their mantle source possibly resembled the source of South Atlantic N-MORB prior to addition of fluids and melts from the subduction channel. However, it must have been more enriched than the estimates of depleted upper mantle from...

  18. A Cenozoic record of the equatorial Pacific carbonate compensation depth. (United States)

    Pälike, Heiko; Lyle, Mitchell W; Nishi, Hiroshi; Raffi, Isabella; Ridgwell, Andy; Gamage, Kusali; Klaus, Adam; Acton, Gary; Anderson, Louise; Backman, Jan; Baldauf, Jack; Beltran, Catherine; Bohaty, Steven M; Bown, Paul; Busch, William; Channell, Jim E T; Chun, Cecily O J; Delaney, Margaret; Dewangan, Pawan; Dunkley Jones, Tom; Edgar, Kirsty M; Evans, Helen; Fitch, Peter; Foster, Gavin L; Gussone, Nikolaus; Hasegawa, Hitoshi; Hathorne, Ed C; Hayashi, Hiroki; Herrle, Jens O; Holbourn, Ann; Hovan, Steve; Hyeong, Kiseong; Iijima, Koichi; Ito, Takashi; Kamikuri, Shin-ichi; Kimoto, Katsunori; Kuroda, Junichiro; Leon-Rodriguez, Lizette; Malinverno, Alberto; Moore, Ted C; Murphy, Brandon H; Murphy, Daniel P; Nakamura, Hideto; Ogane, Kaoru; Ohneiser, Christian; Richter, Carl; Robinson, Rebecca; Rohling, Eelco J; Romero, Oscar; Sawada, Ken; Scher, Howie; Schneider, Leah; Sluijs, Appy; Takata, Hiroyuki; Tian, Jun; Tsujimoto, Akira; Wade, Bridget S; Westerhold, Thomas; Wilkens, Roy; Williams, Trevor; Wilson, Paul A; Yamamoto, Yuhji; Yamamoto, Shinya; Yamazaki, Toshitsugu; Zeebe, Richard E


    Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.

  19. A new integrated tectonic model for the Mesozoic-Early Cenozoic subduction, spreading, accretion and collision history of Tethys adjacent to the southern margin of Eurasia (NE Turkey) (United States)

    Robertson, Alastair; Parlak, Osman; Ustaömer, Timur; Taslı, Kemal; İnan, Nurdan; Dumitrica, Paulian; Karaoǧlan, Fatih


    A major Tethyan suture zone (İzmir-Ankara-Erzincan-Kars Suture Zone) borders the southern margin of Eurasia throughout the Pontides. In eastern Turkey the suture zone includes a range of redeposited terrigenous and volcanogenic sedimentary rocks, pelagic sedimentary rocks and also igneous/metamorphic rocks. The igneous rocks are mostly basaltic blocks and thrust sheets within melange, plus relatively intact, to dismembered, ophiolitic rocks (oceanic crust). Two alternative hypotheses have been developed and tested during this work: 1. The suture zone preserves a single Andean-type active continental margin associated with northward subduction, accretion and arc magmatism during Mesozoic-early Cenozoic time; 2. The suture zone preserves the remnants of two different subduction zones, namely a continental margin subduction zone (as above) and an intra-ocean subduction zone (preferred model). To determine the age of the oceanic crust, relevant to both hypotheses, zircons were extracted from basic ophiolitic rocks (both intact and dismembered) and dated by the U/Pb method (U238/U236) using an ion probe at Edinburgh University. This yielded the following results for the intact ophiolites (Ma): plagiogranite cutting sheeted dykes of the Refahiye ophiolite (east of Erzincan), 183.6±1.7 (2σ); isotropic gabbro from the Karadaǧ ophiolite (northeast of Erzurum), 179.4±1.7 (2σ). In addition, dismembered ophiolites gave the following ages: gabbro cumulate (Bayburt area), 186.2±1.4 (2σ), gabbro cumulate (N of Horasan), 178.1±1.8 (2σ). Furthermore, two samples from a kilometre-sized (arc-related) tonalite body, mapped as cutting a thrust sheet of ophiolitic isotropic gabbro in the Kırdaǧ area, yielded ages of 182.1±3.2 (2σ) and 185.1±3.0 (2σ) Ma. We infer that the ophiolitic and related magmatic arc rocks formed by spreading in a supra-subduction zone setting during the late Early Jurassic (Pliensbachian-Toarcian). This amends former assumptions of a Late

  20. Experimental study of the Mg and Sr isotopic evolution of seawater interacting with basalt between 150 and 300 ° C. (United States)

    Voigt, Martin; Pearce, Christopher R.; Oelkers, Eric H.


    The chemical exchange of material between seawater and the oceanic crust plays a major role in marine geochemical cycles [1]. Isotopic signatures provide an important means of tracing elemental transfer in hydrothermal environments, yet only a limited amount of experimental data on the extent of isotopic fractionation under these conditions is currently available. This study consequently investigated the extent of δ26/24Mg and 87Sr/86Sr isotopic variation during a seawater-basalt interaction experiments at 150, 250 and 290 ° C. A suite of closed system experiments were run for several months at each temperature under saturated water pressure, using either crystalline or glassy basalt as the starting material and a water/rock ratio of 10 or 25. Our results demonstrate that the dissolution of basaltic material in hydrothermal environments occurs at the same time as the precipitation of alteration minerals (mainly smectite and anhydrite), which is consistent with results from similar studies in the past (e.g. [2]). As expected, the rate of reaction using crystalline basalt was slower than with basaltic glass, and both sample types reacted faster at higher temperatures. The 87Sr/86Sr composition of the experimental fluids decreased from the initial seawater value (0.70916) towards the lower basaltic signature during the experiments (0.70317), demonstrating the progressive release of Sr during basalt dissolution. Magnesium was steadily removed from the fluid via the precipitation of clay minerals, with the residual fluids having progressively lighter δ26/24Mg compositions. The mean Mg isotope fractionation factor (αsolid-solution) observed at 250 oC was 1.0005±0.0002, supporting low-temperature evidence that clay minerals preferentially incorporate isotopically heavy magnesium [3]. These experiments provide quantitative information on the extent of Mg isotopic fractionation between fluids and secondary silicate minerals in hydrothermal systems, and demonstrate the

  1. Basalt characterization by means of nuclear and electrical well logging techniques. Case study from Southern Syria

    International Nuclear Information System (INIS)

    Asfahani, Jamal


    Nuclear well logging, including natural gamma ray, density, and neutron-porosity techniques are used with electrical well logging of long and short normal techniques to characterize the basaltic areas largely extended in Southern Syria. Statistical analysis approach with the threshold concept has been adapted for such characterization, where four kinds of basalt have been identified: very hard basalt, hard basalt, fractured basalt, and basalt alteration products. The spectrometric gamma technique has also been applied on the retrieved rock samples in order to determine the radioactive content (eU, eTh, and K%) of the basaltic section in the study area. No radioactive anomalies have been detected, the radioactive values are normal and in the expected range.

  2. Rheological evolution of planetary basalts during cooling and crystallization (United States)

    Sehlke, Alexander

    Basaltic lavas cover large portions of the surface of the Earth and other planets and moons. Planetary basalts are compositionally different from terrestrial basalts, and show a variety of unique large-scale lava flow morphologies unobserved on Earth. They are usually assumed to be much more fluid than basalts on Earth, such as Hawaiian basalt, but their rheology is largely unknown. I synthesized several synthetic silicate melts representing igneous rock compositions of Mars, Mercury, the Moon, Io and Vesta. I measured their viscosity, as well as several terrestrial lavas including Hawaiian basalt, by concentric cylinder and parallel plate viscometry. Planetary melts cover a wide range of viscosity at their liquidus, overlapping with terrestrial basaltic melts. I derived a new viscosity model that is based on the Adam-Gibbs theory of structural relaxation, predicting these viscosities much more accurately than previously published viscosity models. During crystallization, the rheological behavior changes from Newtonian to pseudoplastic. Combining rheology experiments with field observations, the rheological conditions of the pahoehoe to `a`a morphological transition for Hawaiian basalt were determined in strain rate-viscosity space. This transition occurs at temperatures around 1185+/-15°C. For Mercurian lavas, this transition is predicted to occur at higher temperatures around 1250+/-30°C. We find that the rheology of these lavas is broadly similar to terrestrial ones, suggesting that the large smooth volcanic plains observed on Mercury's northern hemisphere are due to flood basalt volcanism rather than unusually fluid lavas. We also show that KREEP lavas, a type of basalt associated with sinuous rilles on the lunar surface, is more likely to form rilles through levee construction, as the high and rapidly increasing viscosity prohibits sufficient thermo-mechanical erosion.

  3. BASALT A: Basaltic Terrains in Idaho and Hawaii as Planetary Analogs for Mars Geology and Astrobiology (United States)

    Hughes, Scott S.; Haberle, Christopher W.; Nawotniak, Shannon E. Kobs; Sehlke, Alexander; Garry, W. Brent; Elphic, Richard C.; Payler, Sam J.; Stevens, Adam H.; Cockell, Charles S.; Brady, Allyson L.; hide


    Assessments of field research target regions are described within two notably basaltic geologic provinces as Earth analogs to Mars. Regions within the eastern Snake River Plain of Idaho and the Big Island of Hawaii, USA, provinces that represent analogs of present-day and early Mars, respectively, were evaluated on the basis of geologic settings, rock lithology and geochemistry, rock alteration, and climate. Each of these factors provide rationale for the selection of specific targets for field research in five analog target regions: (1) Big Craters and (2) Highway lava flows at Craters of the Moon National Monument and Preserve, Idaho; and (3) Mauna Ulu low shield, (4) Kilauea Iki lava lake and (5) Kilauea caldera in the Kilauea Volcano summit region and the East Rift Zone of Hawaii. Our evaluation of compositional and textural differences, as well as the effects of syn- and post-eruptive rock alteration, shows that the basaltic terrains in Idaho and Hawaii provide a way to characterize the geology and major geologic substrates that host biological activity of relevance to Mars exploration. This work provides the foundation to better understand the scientific questions related to the habitability of basaltic terrains, the rationale behind selecting analog field targets, and their applicability as analogs to Mars.

  4. Engineered barrier development for a nuclear waste repository in basalt

    International Nuclear Information System (INIS)

    Smith, M.J.


    The BWIP Engineered Barrier Program has been developed to provide an integrated approach to the development of site-specific Engineered Barrier assemblages for a repository located in basalt. The goal of this program is to specify engineered and natural barriers which will ensure that nuclear and non-radioactive hazardous materials emplaced in a repository in basalt do not exceed acceptable rates of release to the biosphere. A wide range of analytical and experimental activities related to the basalt repository environment, waste package environment, waste/barrier/rock interactions, and barrier performance assessment provide the basis for selection of systems capable of meeting licensing requirements. Work has concentrated on specifying and testing natural and man-made materials which can be used to plug boreholes in basalt and which can be used as multiple barriers to surround nuclear waste forms and containers. The Engineered Barriers Program is divided into two major activities: multiple barrier studies and borehole plugging. 8 figures, 4 tables

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

    Directory of Open Access Journals (Sweden)

    Alireza Bajelan


    disequilibrium textures in the minerals (zoned state, solution and twinning shows a magmatic contamination in mixing volcanic mass. References Aldanmaz, E., Koprubasi, N.O., Gurer, F., Kaymakci, N. and Gournaud, A., 2006. geochemical constraints on the Cenozoic, OIB-type alkaline volcanic rocks of NW Turkey: implications for mantle sources and melting processes. Lithos, 86 (1–2 pp. 50–76. De La Roche, H., Leterrier, J., Grand claude, P. and Marchel, M., 1980. A classification of volcanic and plutonic rocks using R1-R2 diagrams and major elements, it’s relationships with current nomenclature. Chemical Geology, 29(1-4: 183–210. Hirschman, M., 1998. Origin of the transgressive granophyres in the layered series of the Skaergaard intrusion, East Greenland. In: D.J. Geist and C.M. White (Editors.. Journal of Volcanology and Geothermal Research, 52(1-3: 185–207. Irvine, T.N. and Baragar, W.R.A., 1971. A guide to chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 5(8: 448– 523. Moein Vaziri, H., 1997. The history of magmatism in Iran. Tehran University Press, Tehran, 440 pp. (in Persian Moein Vaziri, H. and Aminsobhani, A., 1985. Study of young volcanic region being involved in –Qorveh- Takab. Tehran University Press, Tehran, 350 pp. (in Persian Pearce, J.A. and Cann, J.R., 1973. Tectonic setting of basaltic volcanic rocks determind using traceelements analysis. Earth and Planetary Science Letters, 19(2: 290– 300. Pearce, J.A. and Norry, M.J., 1979. Petrogenetic implications of Ti, Zr, Y and Nb variation in volcanic rocks. Contributions to Mineralogy and Petrology, 69(1: 33– 47. Shelley, D. (Translated by Mohamadzadeh, F., 1993. Igneous and metamorphic rocks under the microscope, classification, textures, microstructures and mineral preferred-orientations. Chapman and Hall, Unwin, London, 445 pp.

  6. Mineral chemistry and petrogenesis of the Gurgur Mount volcanic rocks (Northeast Takab

    Directory of Open Access Journals (Sweden)

    Dariush Esmaeily


    Full Text Available Andesitic and andesitic-basaltic lavas are widespread over most of the ground surface of the Gurgur area altered mostly by the hydrothermal solutions. The main rock forming minerals in these rocks are plagioclase, pyroxene and olivine affected by the hydrothermal solutions. The altered rocks do contain minerals including calcite, sericite and chlorite. Given the results obtained and the mineral chemistry studies, the clinopyroxenes formed in the area are, chemically, calkalkaline and of diopside-augite type formed in subvolcanic to near surface levels contemporaneous with magma ascending. Plagioclase minerals show zoning textures and lie within the two andesine and albite-oligoclase fields. These units, in terms of total rock chemistry, are classified as the calk-alkaline volcanic rocks formed in the continental arcs. On the other hand, on the trace elements chondrite-normalized diagrams and enriched mantle-normalized multi- element diagrams, the LREE enrichment relative to the HREE is observed. The LILE (i.e. Rb, K and Th and the LREE (e.g. La, Ce and Nd show an enrichment in comparison to the HFSE (Zr, Hf, Nb, Yb, Y and Sm. Given the Nd/Th (1.42-1.15, Zr/Nb (12.27-21.22, Ba/La (18.64-29.77 as well as LILE enrichment associated with depletion in Nb, Ta and Ti, an environment related to the subduction zones can be proposed for the area under study. Moreover, the similarity between the REE distribution pattern and the incompatible elements point to the genetic relationship between these rocks. Finally, on the base of the obtained data, it can be concluded that the volcanic rocks in the Gurgur Mountain were likely formed during the extended magmatism of the Urumieh-Dokhtar in the Cenozoic.

  7. Coupled geomechanical/hydrological modeling: an overview of basalt waste isolation project studies

    International Nuclear Information System (INIS)

    Baca, R.G.; Case, J.B.; Patricio, J.G.


    Basalt Waste Isolation Project investigations of the Columbia River basalts are multi-disciplinary in nature with a broad scope spanning such areas as geology, seismology, geochemistry, hydrology, rock mechanics, and many other disciplines as well. In this paper, an overview is presented which surveys recent work on numerical modeling of geomechanical and hydrological processes in a basalt rock environment. A major objective of the ongoing numerical modeling work is to establish a predictive technology base with which to: interpret the interrelationships between geomechanical behavior of rock media, the natural hydrologic phenomena, and repository conditions; evaluate the effectiveness of preconceptual repository designs and assist in the design of in situ field testing; and assess the waste isolation capability of candidate host rocks within the Columbia River basalts. To accomplish this objective, a systems approach has been adopted which is based on the use of digital simulation models

  8. Petrography and petrogenesis of some Indian basaltic achondrites ...

    Indian Academy of Sciences (India)

    oid 4-Vesta (Drake 2001; Barrat 2004; Barrat et al. 2003, 2010; Mittlefehldt 2005; McSween et al. 2011). This is the most abundant class of achon- drites and represents a collection of both volcanic and plutonic rocks formed from basaltic magmas. Keywords. Indian achondrites; HED clan; petrography; mineral chemistry; ...

  9. Study of rock-water-nuclear waste interactions in the Pasco Basin, Washington. Part I. Distribution and composition of secondary and primary mineral phases in basalts of the Pasco Basin, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Benson, L.V.; Teague, L.S.


    In Part I of this report the results of Task III are presented and discussed. The subject of Task III is the study and identification of secondary and primary mineral assemblages in basalts of the Pasco Basin of southeastern Washington. In particular, we have determined the relative amounts, crystallization sequence, and compositions of secondary minerals found lining vesicle and fracture surfaces. This information, together with data on the chemical composition of primary minerals and the extent to which they have undergone dissolution, has been used in theoretical simulations of mass transfer which is the subject of Part II (Task IV) of this report.

  10. Study of rock-water-nuclear waste interactions in the Pasco Basin, Washington. Part I. Distribution and composition of secondary and primary mineral phases in basalts of the Pasco Basin, Washington

    International Nuclear Information System (INIS)

    Benson, L.V.; Teague, L.S.


    In Part I of this report the results of Task III are presented and discussed. The subject of Task III is the study and identification of secondary and primary mineral assemblages in basalts of the Pasco Basin of southeastern Washington. In particular, we have determined the relative amounts, crystallization sequence, and compositions of secondary minerals found lining vesicle and fracture surfaces. This information, together with data on the chemical composition of primary minerals and the extent to which they have undergone dissolution, has been used in theoretical simulations of mass transfer which is the subject of Part II (Task IV) of this report

  11. Fotointerpretação de padrões de drenagem de bacias hidrográficas na caracterização de solos desenvolvidos de rochas eruptivas básicas no estado do Paraná Drainage pattern photointerpretation in the characterization of soils developed from basaltic rocks in the state of Paraná, Brazil

    Directory of Open Access Journals (Sweden)

    J.A.M. Demattê


    Full Text Available Utilizando fotografias aéreas na escala 1:25.000, o presente trabalho teve por objetivo caracterizar os padrões da rede de drenagem, a partir de bacias hidrográficas de 3ª ordem de ramificação, em três regiões de solos desenvolvidos de rochas eruptivas básicas no Estado do Paraná. As unidades de mapeamento são: brunizem avermelhado+litossolos associados, terra roxa estruturada e latossolo roxo. A densidade de drenagem, freqüência de rios e a razão de textura média foram as propriedades mais significativas na separação dos solos das áreas, permitindo também constatar variações de drenagem dentro de uma mesma unidade de solo. Pelo teste de semelhança geométrica foi possível obter "grupos" de bacias representativas de uma mesma unidade de mapeamento. Há estreita correlação entre densidade de drenagem e índices de intemperismo dos solos.Aerial photographs in the scale of 1:25.000 were used to study the drainage network and its Quantitative and descriptive characteristics in 3 areas located in Paraná , for soils developed from basaltic rocks. The soil mapping units were the following: reddish brunizen or an argiudoll, terra roxa estruturada or a rodudalf and "roxo" latosol or an acrortox. The drainage density, river frequency and texture ratio, in watersheds were the best index for characterizing the soil unit. Also, they were useful in the separation of watersheds with inclusion of different soils. By using the geometric test, it was possible to obtain "groups" of watersheds representatives of the same soil. There was a close correlation between drainage density and weathering index, for soils developed from basaltic rocks.

  12. Alaskan Peninsula Cenozoic stratigraphy: stratigraphic sequences and current research

    Energy Technology Data Exchange (ETDEWEB)

    Allison, R.C.; Armentrout, J.M.


    Geology of the Alaska Peninsula-Island Arc and Continental Margin, by C.A. Burk, is the principal reference for stratigraphic studies on the Alaska Peninsula. Burk mapped the Phanerozoic stratigraphy and provided a geologic history and structural interpretation of the area between Wide Bay and Unimak Island. Cenozoic rocks were mapped as three unconformity-bounded sequences. Recognition of specific formations was difficult due to similarity of lithofacies, isolated outcrops, rapid facies changes, and alteration and burial by young volcanics. Consequently, megafossil assemblages were relied upon to facilitate correlations between study areas. The three unconformity-bounded Cenozoic sequences are: (1) the Paleogene Beaver Bay Group consisting of three formations: the dominantly nonmarine Tolstoi Formation, the dominantly marine Stepovak Formation, and the volcanic Meshik Formation. Current work suggests these units are at least in part coeval facies of late Paleocene through Oligocene age. (2) The Neogene Bear Lake Formation consisting of the lower Unga Conglomerate Member and an unnamed upper member. Rapid facies changes and incorrect reports of fossil occurrence have resulted in confusion of stratigraphic relationships within this sequence of middle to late Miocene age. (3) A late Neogene informally defined upper sequence consisting of interbedded marginal marine, coastal-plain, and volcanic facies. Current work suggests this sequence is Pliocene through Pleistocene in age.

  13. Dissolution and secondary mineral precipitation in basalts due to reactions with carbonic acid (United States)

    Kanakiya, Shreya; Adam, Ludmila; Esteban, Lionel; Rowe, Michael C.; Shane, Phil


    One of the leading hydrothermal alteration processes in volcanic environments is when rock-forming minerals with high concentrations of iron, magnesium, and calcium react with CO2 and water to form carbonate minerals. This is used to the advantage of geologic sequestration of anthropogenic CO2. Here we experimentally investigate how mineral carbonation processes alter the rock microstructure due to CO2-water-rock interactions. In order to characterize these changes, CO2-water-rock alteration in Auckland Volcanic Field young basalts (less than 0.3 Ma) is studied before and after a 140 day reaction period. We investigate how whole core basalts with similar geochemistry but different porosity, permeability, pore geometry, and volcanic glass content alter due to CO2-water-rock reactions. Ankerite and aluminosilicate minerals precipitate as secondary phases in the pore space. However, rock dissolution mechanisms are found to dominate this secondary mineral precipitation resulting in an increase in porosity and decrease in rigidity of all samples. The basalt with the highest initial porosity and volcanic glass volume shows the most secondary mineral precipitation. At the same time, this sample exhibits the greatest increase in porosity and permeability, and a decrease in rock rigidity post reaction. For the measured samples, we observe a correlation between volcanic glass volume and rock porosity increase due to rock-fluid reactions. We believe this study can help understand the dynamic rock-fluid interactions when monitoring field scale CO2 sequestration projects in basalts.

  14. Cenozoic to Cretaceous paleomagnetic dataset from Egypt: New data, review and global analysis (United States)

    Perrin, Mireille; Saleh, Ahmed


    Different phases of igneous activity took place in Egypt during the Mesozoic and the Cenozoic and oriented samples were collected from three Cenozoic localities (Baharya oasis in the Western Desert, Abu Had in the Eastern Desert and Quseir along the Red Sea coast), and four Cretaceous localities (Toshki & Abu Simbel south of Aswan, and Shalaten & Abu Shihat along the Red Sea coast). Rock magnetic properties of the samples indicate magnetite and titanomagnetite as the main carrier of the remanent magnetization. Following stepwise demagnetization, characteristic remanent directions were identified only for 62% of the samples, a fairly low rate for that type of samples, and 8 new paleomagnetic poles were calculated. All our Cenozoic poles fall clearly off Master Polar Wander Paths proposed for South Africa. Therefore, all paleomagnetic results, previously published for Egypt, were compiled from Cretaceous to Quaternary. The published poles largely overlap, blurring the Egyptian Apparent Polar Wander Path. A new analysis at the site level was then carried out. Only poles having a kappa larger than 50 were selected, and new pole positions were calculated by area and by epoch, when at least 3 sites were available. Even though the selection drastically reduced the number of considered poles, it allows definition of a reliable Cenozoic apparent polar wander trend for Egypt that differs from the South African Master Polar Wander Path by about 10-15 °. If the Cretaceous igneous poles are in good agreement with the rest of the African data, the sedimentary poles plot close to the Cenozoic portion of the South African Master Polar Wander Path, a discrepancy that could be related either to inclination flattening and/or error on age and/or remagnetization in the Cenozoic.

  15. Crustal extension and magmatism during the mid-Cenozoic ignimbrite flare-up in the Guazapares Mining District and Cerocahui basin regions, northern Sierra Madre Occidental, western Chihuahua, Mexico (United States)

    Murray, Bryan Patrick

    Silicic large igneous provinces are significant in the geologic record, due to their unusually extensive areal coverage (>100,000 km2) and large volumes (>250,000 km3), and may be characteristic of continental regions undergoing broad lithospheric extension. The Sierra Madre Occidental of northwestern Mexico is the biggest and best-preserved silicic large igneous province of the Cenozoic and is considered part of the extensive mid-Cenozoic ignimbrite flare-up that affected much of the southwestern North American Cordillera. Despite its size and preservation, very little is known about the geology of the Sierra Madre Occidental, and the timing and spatial extent of ignimbrite flare-up volcanism in relation to crustal extension is relatively unknown. This study presents new geologic mapping, stratigraphy, zircon U-Pb laser ablation ICP-MS dating, modal analysis, and geochemical data from the Guazapares Mining District and Cerocahui basin regions, two adjacent areas of the northern Sierra Madre Occidental in western Chihuahua. The rock exposure and topographic relief in this previously unmapped ~450 km2 area make it ideal for studying the relationships between silicic large igneous province volcanism and crustal extension. Three informal formations are identified in the study area: (1) the ca. 27.5 Ma Parajes formation, a ~1-km-thick succession of primarily welded silicic outflow ignimbrite sheets erupted from sources within ~50--100 km of the study area that were active during the Early Oligocene pulse of the mid-Cenozoic ignimbrite flare-up; (2) the ca. 27--24.5 Ma Temoris formation, composed primarily of locally erupted mafic-intermediate lavas and associated intrusions with interbedded alluvial deposits, likely related to rocks of the Southern Cordillera basaltic andesite province that were intermittently erupted across all of the northern Sierra Madre Occidental following the Early Oligocene ignimbrite pulse; and (3) the ca. 24.5--23 Ma Sierra Guazapares

  16. Identification of Rocks on Planetary Surface Using Husar-9 Rover Camera: Field Work Simulations with Hunveyor-9 Space Probe Model System at Eötvös High School, Tata, Hungary (United States)

    Magyar, I.; Badics, A.; Bakonyi, I.; Csiszár, Á.; Franko, M.; Gyürki, Á.; Héricz, M.; Marschall, B.; Nagyházi, Á.; Varga, T. N.; Végh, Gy.; Varga, T. P.; Bérczi, Sz.


    We studied the rock types along the Husar-9 rover’s path and identified them on the basis of their shape, color and surface textures: komatiite, basalt, granite, conglomerate, schist rock, porphyritic granite, suevite breccia, and vesicular basalt.

  17. East African Cenozoic vegetation history. (United States)

    Linder, Hans Peter


    The modern vegetation of East Africa is a complex mosaic of rainforest patches; small islands of tropic-alpine vegetation; extensive savannas, ranging from almost pure grassland to wooded savannas; thickets; and montane grassland and forest. Here I trace the evolution of these vegetation types through the Cenozoic. Paleogene East Africa was most likely geomorphologically subdued and, as the few Eocene fossil sites suggest, a woodland in a seasonal climate. Woodland rather than rainforest may well have been the regional vegetation. Mountain building started with the Oligocene trap lava flows in Ethiopia, on which rainforest developed, with little evidence of grass and none of montane forests. The uplift of the East African Plateau took place during the middle Miocene. Fossil sites indicate the presence of rainforest, montane forest and thicket, and wooded grassland, often in close juxtaposition, from 17 to 10 Ma. By 10 Ma, marine deposits indicate extensive grassland in the region and isotope analysis indicates that this was a C 3 grassland. In the later Miocene rifting, first of the western Albertine Rift and then of the eastern Gregory Rift, added to the complexity of the environment. The building of the high strato-volcanos during the later Mio-Pliocene added environments suitable for tropic-alpine vegetation. During this time, the C 3 grassland was replaced by C 4 savannas, although overall the extent of grassland was reduced from the mid-Miocene high to the current low level. Lake-level fluctuations during the Quaternary indicate substantial variation in rainfall, presumably as a result of movements in the intertropical convergence zone and the Congo air boundary, but the impact of these fluctuations on the vegetation is still speculative. I argue that, overall, there was an increase in the complexity of East African vegetation complexity during the Neogene, largely as a result of orogeny. The impact of Quaternary climatic fluctuation is still poorly understood

  18. Additive Construction using Basalt Regolith Fines (United States)

    Mueller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Lippitt, Thomas C.; Mantovani, James G.; Nugent, Matthew W.; Townsend, Ivan I.


    Planetary surfaces are often covered in regolith (crushed rock), whose geologic origin is largely basalt. The lunar surface is made of small-particulate regolith and areas of boulders located in the vicinity of craters. Regolith composition also varies with location, reflecting the local bedrock geology and the nature and efficiency of the micrometeorite-impact processes. In the lowland mare areas (suitable for habitation), the regolith is composed of small granules (20 - 100 microns average size) of mare basalt and volcanic glass. Impacting micrometeorites may cause local melting, and the formation of larger glassy particles, and this regolith may contain 10-80% glass. Studies of lunar regolith are traditionally conducted with lunar regolith simulant (reconstructed soil with compositions patterned after the lunar samples returned by Apollo). The NASA Kennedy Space Center (KSC) Granular Mechanics & Regolith Operations (GMRO) lab has identified a low fidelity but economical geo-technical simulant designated as Black Point-1 (BP-1). It was found at the site of the Arizona Desert Research and Technology Studies (RATS) analog field test site at the Black Point lava flow in adjacent basalt quarry spoil mounds. This paper summarizes activities at KSC regarding the utilization of BP-1 basalt regolith and comparative work with lunar basalt simulant JSC-1A as a building material for robotic additive construction of large structures. In an effort to reduce the import or in-situ fabrication of binder additives, we focused this work on in-situ processing of regolith for construction in a single-step process after its excavation. High-temperature melting of regolith involves techniques used in glassmaking and casting (with melts of lower density and higher viscosity than those of metals), producing basaltic glass with high durability and low abrasive wear. Most Lunar simulants melt at temperatures above 1100 C, although melt processing of terrestrial regolith at 1500 C is not

  19. Cenozoic Tectonic Characteristics in the Adare Basin, West Ross Sea: Evidence From Seismic Profiles (United States)

    Zhang, Q.; Gao, J.; Ding, W.


    Based on the geophysical data obtained from the Adare Basin and its adjacent areas, West Ross Sea, the authors employed the frequency wave-number filtering technique to recover the newly processed dataset with high signal noise ratio and complete seismic event which highly contributes to reveal more detailed deep-seated geological structures than previously thought. The structural features and magmatism of the study area in Cenozoic were classified and analyzed. Combined with glaciation, the associated sedimentary facies were summarized systematically. The authors' analysis revealed that, at 16 Ma, under the influence of the thermal effect caused by residual magmatism and asymmetric spreading of Adare Basin in the initial period, surrounding areas of two flanks of the Adare trough were characterized by uplift folds and tilted uplift zone, respectively. The small-scale uplift fold zone was characterized by nearly upright faults and folds and was located in the southern part of the eastern flank, whereas the tilted uplift zone dominated in the corresponding district of western flank that reached the continental margin. By utilizing the contact relationship between igneous rocks and surrounding rocks, igneous rocks can be divided into two periods: early-stage and late Cenozoic igneous rocks. The early-stage rocks are generally located dispersedly in the tilted uplift zone and the age is poorly known. It is suggested that they were related to the residual magmatism. On the other hand, the spatial distribution of Late Cenozoic igneous rocks, formed not earlier 5.5 Ma, was extensive and scattered, almost covering the whole study area, which indicates that they might be unrelated to the rifting in space and time, instead they were affected by decompression melting of the mantle because of the large-scale deglaciation since Pliocene.

  20. Petrography, mineral chemistry and geochemistry of post-ophiolitic volcanic rocks in the Ratouk area (south of Gazik, east of Iran

    Directory of Open Access Journals (Sweden)

    Zahra Vahedi Tabas


    environments and active fault zone and originated from enriched mantle or asthenosphere. Lithospheric thickness maps derived from the speed of shear waves show that the lithosphere is thin in east of Iran and volcanic activity has occurred along strike-slip faults (Walker et al., 2009. Therefore, according to other similar basaltic eruptions that have occurred in the Sistan suture zone, we can say that all of them are from the same origin and as a result of deep fractures within continental plates that provide conditions for the eruption of basaltic magma. Andesitic units in the Ratouk area are located within the active continental margin and show similar characteristics to rocks of the Subduction Zone in terms of composition. Acknowledgements The authors would like to thank reviewers for the constructive comments which greatly contributed to the improvement of the manuscript. References Alici, P., Temel, A. and Gourgaud, A., 2002. Pb-Nd Sr isotope and trace element geochemistry of Quaternary extension-related alkaline volcanism: a case study of Kula region western Anatolia, Turkey. Journal of Volcanology and Geothermal Research, 115(3: 487-510. Alishahi, E., 2012. Petrology and Geochemistry of volcanic rocks in Nasfandeh area (east of Nehbandan –Iran. M.Sc. Thesis, University of Birjand, Birjand, Iran, 211 pp. (in Persian with English abstract Chen, Y., Zhang, Y., Graham, D., Su, S. and Deng, J., 2007. Geochemistry of Cenozoic basalts and mantle xenoliths in Northeast China. Lithos, 96(1: 108–126. Emami, M.H., 2000. Magmatism in Iran. Geological Survey of Iran, Tehran, 608 pp. Ghasempour, M.R., Byabangard, H., Boomeri, M. and Moridi, A., 2011. Geochemistry and tectonic setting of Plio-Quaternary basaltic rocks in SE Nehbandan, eastern Iran. Iranian Journal of Crystallography and Mineralogy, 18(4: 695-708. (in Persian with English abstract Guillou, Y., Maurizot, P., Vaslet, D. and Dellavillen, H., 1981. Geological map of Gazik, Scale1:100000. Geological Survey of Iran

  1. Preliminary Hydrogeologic Characterization Results from the Wallula Basalt Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    B.P. McGrail; E. C. Sullivan; F. A. Spane; D. H. Bacon; G. Hund; P. D. Thorne; C. J. Thompson; S. P. Reidel; F. S. Colwell


    The DOE's Big Sky Regional Carbon Sequestration Partnership has completed drilling the first continental flood basalt sequestration pilot borehole to a total depth (TD) of 4,110 feet on the Boise White Paper Mill property at Wallula, Washington. Site suitability was assessed prior to drilling by the 2007-2008 acquisition, processing and analysis of a four-mile, five-line three component seismic swath, which was processed as a single data-dense line. Analysis of the seismic survey data indicated a composite basalt formation thickness of {approx}8,000 feet and absence of major geologic structures (i.e., faults) along the line imaged by the seismic swath. Drilling of Wallula pilot borehole was initiated on January 13, 2009 and reached TD on April 6, 2009. Based on characterization results obtained during drilling, three basalt breccia zones were identified between the depth interval of 2,716 and 2,910 feet, as being suitable injection reservoir for a subsequent CO2 injection pilot study. The targeted injection reservoir lies stratigraphically below the massive Umtanum Member of the Grande Ronde Basalt, whose flow-interior section possesses regionally recognized low-permeability characteristics. The identified composite injection zone reservoir provides a unique and attractive opportunity to scientifically study the reservoir behavior of three inter-connected reservoir intervals below primary and secondary caprock confining zones. Drill cuttings, wireline geophysical logs, and 31one-inch diameter rotary sidewall cores provided geologic data for characterization of rock properties. XRF analyses of selected rock samples provided geochemical characterizations of the rocks and stratigraphic control for the basalt flows encountered by the Wallula pilot borehole. Based on the geochemical results, the pilot borehole was terminated in the Wapshilla Ridge 1 flow of the Grande Ronde Basalt Formation. Detailed hydrologic test characterizations of 12 basalt interflow

  2. Magnesium-rich Basalts on Mercury (United States)

    Martel, L. M. V.


    X-ray and gamma-ray spectrometers on NASA's MESSENGER spacecraft are making key measurements regarding the composition and properties of the surface of Mercury, allowing researchers to more clearly decipher the planet's formation and geologic history. The origin of the igneous rocks in the crust of Mercury is the focus of recent research by Karen Stockstill-Cahill and Tim McCoy (National Museum of Natural History, Smithsonian Institution), along with Larry Nittler and Shoshana Weider (Carnegie Institution of Washington) and Steven Hauck II (Case Western Reserve University). Using the well-known MELTS computer code Stockstill-Cahill and coauthors worked with MESSENGER-derived and rock-analog compositions to constrain petrologic models of the lavas that erupted on the surface of Mercury. Rock analogs included a partial melt of the Indarch meteorite and a range of Mg-rich terrestrial rocks. Their work shows the lavas on Mercury are most similar to terrestrial magnesian basalt (with lowered FeO content). The implications of the modeling are that Mg-rich lavas came from high-temperature sources in Mercury's mantle and erupted at high temperature with exceptionally low viscosity into thinly bedded and laterally extensive flows, concepts open to further evaluation by laboratory experiments and by geologic mapping of Mercury's surface using MESSENGER's imaging system and laser altimeter to document flow features and dimensions.

  3. Groundwater quality in the Columbia Plateau, Snake River Plain, and Oahu basaltic-rock and basin-fill aquifers in the Northwestern United States and Hawaii, 1992-2010 (United States)

    Frans, Lonna M.; Rupert, Michael G.; Hunt, Charles D.; Skinner, Kenneth D.


    This assessment of groundwater-quality conditions of the Columbia Plateau, Snake River Plain, and Oahu for the period 1992–2010 is part of the U.S. Geological Survey’s National Water Quality Assessment (NAWQA) program. It shows where, when, why, and how specific water-quality conditions occur in groundwater of the three study areas and yields science-based implications for assessing and managing the quality of these water resources. The primary aquifers in the Columbia Plateau, Snake River Plain, and Oahu are mostly composed of fractured basalt, which makes their hydrology and geochemistry similar. In spite of the hydrogeologic similarities, there are climatic differences that affect the agricultural practices overlying the aquifers, which in turn affect the groundwater quality. Understanding groundwater-quality conditions and the natural and human factors that control groundwater quality is important because of the implications to human health, the sustainability of rural agricultural economies, and the substantial costs associated with land and water management, conservation, and regulation.

  4. Petrological, magnetic and chemical properties of basalt dredged from an abyssal hill in the North-east pacific (United States)

    Luyendyk, B.P.; Engel, C.G.


    OVER the years, samples of basalt from the oceanic crust have been taken mainly from seamounts, fracture zones and ridge and rise crests1-6, and rarely from the vast fields of abyssal hills which cover a large part of the deep-sea floor. The basalt sampled from the deeper regions of the oceanic crust (for example, on fault scarps) is a distinct variety of tholeiitic basalt, while alkali basalt is restricted to the volcanic edifices4. Oceanic tholeiitic basalt differs from alkali basalt and continental tholeiite chiefly in having a relatively low percentage of K2O (0.2 weight per cent)4. Some authors have speculated that this type of tholeiitic basalt is the major extrusion from the upper mantle and constitutes the predominant rock type in the upper oceanic crust. ?? 1969 Nature Publishing Group.

  5. Mineralogy, geochemistry and expansion testing of an alkali-reactive basalt from western Anatolia, Turkey

    International Nuclear Information System (INIS)

    Copuroglu, Oguzhan; Andic-Cakir, Ozge; Broekmans, Maarten A.T.M.; Kuehnel, Radko


    In this paper, the alkali-silica reaction performance of a basalt rock from western Anatolia, Turkey is reported. It is observed that the rock causes severe gel formation in the concrete microbar test. It appears that the main source of expansion is the reactive glassy phase of the basalt matrix having approximately 70% of SiO 2 . The study presents the microstructural characteristics of unreacted and reacted basalt aggregate by optical and electron microscopy and discusses the possible reaction mechanism. Microstructural analysis revealed that the dissolution of silica is overwhelming in the matrix of the basalt and it eventually generates four consequences: (1) Formation of alkali-silica reaction gel at the aggregate perimeter, (2) increased porosity and permeability of the basalt matrix, (3) reduction of mechanical properties of the aggregate and (4) additional gel formation within the aggregate. It is concluded that the basalt rock is highly prone to alkali-silica reaction. As an aggregate, this rock is not suitable for concrete production.

  6. Maar-diatreme volcanism relating to the pyroclastic sequence of a newly discovered high-alumina basalt in the Maroa Volcanic Centre, Taupo Volcanic Zone, New Zealand (United States)

    Kósik, S.; Németh, K.; Procter, J. N.; Zellmer, G. F.


    Diatreme sequences have previously been described from drill holes within the Taupo Volcanic Zone. The newly discovered Te Hukui Basalt exhibits deep excavation of country rocks that do not appear elsewhere at the surface. The basalt is characterized by proximal deposition of pyroclastic deposits relating to phreatomagmatism. The geochemical composition classifies these rocks as high-alumina basalts. They erupted along the Orakeikorako Fault at the same location where rhyolitic activity of Puketerata occurred at a later point in time. The petrological characteristics of the basalts indicate the mixing of mafic melt with crystalline mush relating to more evolved magmas. The new basaltic occurrence supports frequent mafic recharge of shallow magma reservoirs, inducing basaltic eruptions, in this case the mafic magma intruding into highly crystallized mush zones. This may explain why basaltic eruptions mostly occur on the edge of the central extensional part of the Taupo Volcanic Zone.

  7. Surface exposure dating of Holocene basalt flows and cinder cones in the Kula volcanic field (western Turkey) using cosmogenic 3He and 10Be (United States)

    Heineke, Caroline; Niedermann, Samuel; Hetzel, Ralf; Akal, Cüneyt


    The Kula volcanic field is the youngest volcanic province in western Anatolia and covers an area of about 600 km2 around the town Kula (Richardson-Bunbury, 1996). Its alkali basalts formed by melting of an isotopically depleted mantle in a region of long-lived continental extension and asthenospheric upwelling (Prelevic et al., 2012). Based on morphological criteria and 40Ar/39Ar dating, four phases of Quaternary activity have been distinguished in the Kula volcanic field (Richardson-Bunbury, 1996; Westaway et al., 2006). The youngest lava flows are thought to be Holocene in age, but so far only one sample from this group was dated by 40Ar/39Ar at 7±2 ka (Westaway et al., 2006). In this study, we analysed cosmogenic 3He in olivine phenocrysts from three basalt flows and one cinder cone to resolve the Holocene history of volcanic eruptions in more detail. In addition, we applied 10Be exposure dating to two quartz-bearing xenoliths found at the surface of one flow and at the top of one cinder cone. The exposure ages fall in the range between ~500 and ~3000 years, demonstrating that the youngest volcanic activity is Late Holocene in age and therefore distinctly younger than previously envisaged. Our results show that the Late Holocene lava flows are not coeval but formed over a period of a few thousand years. We conclude that surface exposure dating of very young volcanic rocks provides a powerful alternative to 40Ar/39Ar dating. References Prelevic, D., Akal, C. Foley, S.F., Romer, R.L., Stracke, A. and van den Bogaard, P. (2012). Ultrapotassic mafic rocks as geochemical proxies for post-collisional dynamics of orogenic lithospheric mantle: the case of southwestern Anatolia, Turkey. Journal of Petrology, 53, 1019-1055. Richardson-Bunbury, J.M. (1996). The Kula Volcanic Field, western Turkey: the development of a Holocene alkali basalt province and the adjacent normal-faulting graben. Geological Magazine, 133, 275-283. Westaway, R., Guillou, H., Yurtmen, S., Beck, A

  8. Arsenogoyazite in Cenozoic volcanic tuff at Tabalaopa Basin, Chihuahua, Mexico (United States)

    Ren, M.; Rodriguez, A.; Goodell, P.


    Arsenogoyazite has been identified in Cenozoic volcanic tuff at Tabalaopa Basin, Chihuahua, Mexico. Tabalaopa Basin contains volcanic strata and the unconsolidated Quaternary deposit. Cenozoic volcanic tuff forms the low hill terrene in this area. It is a major reservoir for the City of Chihuahua groundwater. Arsenic anomaly (more than 20 ppb) has been observed at El Mimbre, northeast of the city. The exposed reddish color volcanic rocks are felsic welded tuff and rhyolite. Sanidine, quartz, and biotite phenocrysts show linear distribution within the fine grain matrix. The rocks contain large amount of vesicles which are lineated with the welding bends. White and colorless microsize crystals formed on the well of the cavities and the majority of them are K-feldspar. Quartz, Ti-magnetite, and arsenogoyazite are coexisting with feldspars. The sizes of the crystals in the cavities are 10 to several 10s of micrometers. The arsenic x-ray maps have been collected for the rock sections to locate the arsenic minerals. The crystals in cavities show euhedral shape. Most arsenic containing crystals have a near cubic form with triangle surfaces at some corners. The high resolution field-emission SEM images have been collected to study the symmetry of the crystals. EDS spectra for the high arsenic phases show three major elements As-Al-Sr and also minor amount of P-S-REE-Ca-Fe-Si. Since the arsenic minerals are growing on the wall of the vesicle, it is difficult to perform good electron microprobe analysis. Some primary microprobe data give following results in weight percent: SrO 11.8-13.1, CaO 0.2-0.3, FeO 0.3-0.5, Al2O3 28.6-30.9, La2O3 2.4-2.5, Ce2O3 2.3-.24, SiO2 1.1-3.6, As2O5 32.4-35.2, P2O5 1.7-1.9, SO3 0.8-1.4. This chemistry is similar to the reported arsenogoyazite chemical data. So this high arsenic phase is identified as arsenogoyazite. The arsenic anomaly in groundwater at El Mimbre, Chihuahua should be contributed from this arsenic mineral phase in the strata.

  9. Geochemical constraints on the evolution of mafic and felsic rocks in ...

    Indian Academy of Sciences (India)

    Granites are emplaced later, crosscutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and ...

  10. Basic rocks in Finland

    International Nuclear Information System (INIS)

    Piirainen, T.; Gehoer, S.; Iljina, M.; Kaerki, A.; Paakkola, J.; Vuollo, J.


    Basic igneous rocks, containing less than 52% SiO 2 , constitute an important part of the Finnish Archaean and Proterozoic crust. In the Archaean crust exist two units which contain the majority of the basic rocks. The Arcaean basic rocks are metavolcanics and situated in the Greenstone Belts of Eastern Finland. They are divided into two units. The greenstones of the lower one are tholeiites, komatiites and basaltic komatiites. The upper consists of bimodal series of volcanics and the basic rocks of which are Fe-tholeiites, basaltic komatiites and komatiites. Proterozoic basic rocks are divided into seven groups according to their ages. The Proterozoic igneous activity started by the volominous basic magmatism 2.44 Ga ago. During this stage formed the layered intrusions and related dykes in the Northern Finland. 2.2 Ga old basic rocks are situated at the margins of Karelian formations. 2.1 Ga aged Fe-tholeiitic magmatic activity is widespread in Eastern and Northern Finland. The basic rocks of 1.97 Ga age group are met within the Karelian Schist Belts as obducted ophiolite complexes but they occur also as tholeiitic diabase dykes cutting the Karelian schists and Archean basement. The intrusions and the volcanics of the 1.9 Ga old basic igneous activity are mostly encountered around the Granitoid Complex of Central Finland. Subjotnian, 1.6 Ga aged tholeiitic diabases are situated around the Rapakivi massifs of Southern Finland, and postjotnian, 1.2 Ga diabases in Western Finland where they form dykes cutting Svecofennian rocks

  11. Zircon evidence for incorporation of terrigenous sediments into the magma source of continental basalts. (United States)

    Xu, Zheng; Zheng, Yong-Fei; Zhao, Zi-Fu


    Crustal components may be incorporated into continental basalts by either shallow contamination or deep mixing. While the former proceeds at crustal depths with common preservation of refractory minerals, the latter occurs at mantle depths with rare survival of relict minerals. Discrimination between the two mechanisms has great bearing to subcontinental mantle geochemistry. Here we report the occurrence of relict zircons in Cenozoic continental basalts from eastern China. A combined study of zircon U-Pb ages and geochemistry indicates that detrital zircons were carried by terrigenous sediments into a subcontinental subduction zone, where the zircon were transferred by fluids into the magma sources of continental basalts. The basalts were sampled from three petrotectonic units with distinct differences in their magmatic and metamorphic ages, making the crustal contamination discernible. The terrigenous sediments were carried by the subducting oceanic crust into the asthenospheric mantle, producing both soluble and insoluble materials at the slab-mantle interface. These materials were served as metasomatic agents to react with the overlying mantle wedge peridotite, generating a kind of ultramafic metasomatites that contain the relict zircons. Therefore, the occurrence of relict zircons in continental basalts indicates that this refractory mineral can survive extreme temperature-pressure conditions in the asthenospheric mantle.

  12. Genetic aspects of basalts from the Carlsberg Ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Iyer, S.D.

    and three decades later, other workers 5 ? 7 reported the pre s ence of ultrabasics, gab - bros, dolerites, spilites and metamorphosed effusiv es besides basalts along different segments of the CR. Isotopes and rare earth element contents of rocks..., although less dominant, usually occurs as anhedral to euhedral, skeletal and la n tern - shaped forms in the groundmass and as micro - pheno - crysts while zoned olivine is rare. The ore minerals are mainly pyrite, chalcopyrite and magnetite 17...

  13. Hydrothermal interactions of cesium and strontium phases from spent unreprocessed fuel with basalt phases and basalts

    Energy Technology Data Exchange (ETDEWEB)

    Komarneni, S.; Scheetz, B.E.; McCarthy, G.J.; Coons, W.E.


    This investigation is a segment of an extensive research program aimed at investigating the feasibility of long-term, subsurface storage of commercial nuclear waste. Specifically, it is anticipated that the waste will be housed in a repository mined from the basalt formations which lie beneath the Hanford Site. The elements monitored during the present experiments were Cs and Sr. These two elements represent significant biohazards if released from a repository and are the major heat producing radionuclides present in commercial radioactive waste. Several Cs phases and/or solutions were reacted with either isolated basalt phases or bulk-rock basalt, and the resulting solids and solutions were analyzed. The hydrothermal reactivity of SrZrO/sub 3/, which is believed to be a probable host for Sr in SFE was investigated. While so far no evidence exists which indicates that Sr is present in a water soluble phase in spent fuel elements (SFE), detailed investigation of a potential hazard is warranted. This investigation has determined that some Cs compounds likely to be stable components of spent fuel (i.e., CsOH, Cs/sub 2/MoO/sub 4/, Cs/sub 2/U/sub 2/O/sub 7/) have significant hydrothermal solubilities. These solubilities are greatly decreased in the presence of basalt and/or basalt minerals. The decrease in the amount of Cs in solution results from reactions which form pollucite and/or CsAlSiO/sub 4/, with the production of pollucite exceeding that of CsAlSiO/sub 4/. Dissolution of ..beta..-Cs/sub 2/U/sub 2/O/sub 7/ implies solubilizing a uranium species to an undetermined extent. The production of schoepite (UO/sub 3/.3H/sub 2/O) during some experiments containing basalt phases, indicates a tendency to oxidize U/sup 4 +/ to U/sup 6 +/. When diopside (nominally CaMgSi/sub 2/O/sub 6/) and ..beta..-Cs/sub 2/U/sub 2/O/sub 7/ were hydrothermally reacted, at 300/sup 0/C both UO/sub 2/ and UO/sub 3/.3H/sub 2/O were produced. Results of experiments on SrZrO/sub 3/ show it to be

  14. Hydrothermal interactions of cesium and strontium phases from spent unreprocessed fuel with basalt phases and basalts

    International Nuclear Information System (INIS)

    Komarneni, S.; Scheetz, B.E.; McCarthy, G.J.; Coons, W.E.


    This investigation is a segment of an extensive research program aimed at investigating the feasibility of long-term, subsurface storage of commercial nuclear waste. Specifically, it is anticipated that the waste will be housed in a repository mined from the basalt formations which lie beneath the Hanford Site. The elements monitored during the present experiments were Cs and Sr. These two elements represent significant biohazards if released from a repository and are the major heat producing radionuclides present in commercial radioactive waste. Several Cs phases and/or solutions were reacted with either isolated basalt phases or bulk-rock basalt, and the resulting solids and solutions were analyzed. The hydrothermal reactivity of SrZrO 3 , which is believed to be a probable host for Sr in SFE was investigated. While so far no evidence exists which indicates that Sr is present in a water soluble phase in spent fuel elements (SFE), detailed investigation of a potential hazard is warranted. This investigation has determined that some Cs compounds likely to be stable components of spent fuel (i.e., CsOH, Cs 2 MoO 4 , Cs 2 U 2 O 7 ) have significant hydrothermal solubilities. These solubilities are greatly decreased in the presence of basalt and/or basalt minerals. The decrease in the amount of Cs in solution results from reactions which form pollucite and/or CsAlSiO 4 , with the production of pollucite exceeding that of CsAlSiO 4 . Dissolution of β-Cs 2 U 2 O 7 implies solubilizing a uranium species to an undetermined extent. The production of schoepite (UO 3 .3H 2 O) during some experiments containing basalt phases, indicates a tendency to oxidize U 4+ to U 6+ . When diopside (nominally CaMgSi 2 O 6 ) and β-Cs 2 U 2 O 7 were hydrothermally reacted, at 300 0 C both UO 2 and UO 3 .3H 2 O were produced. Experiments on SrZrO 3 show it to be an unreactive phase

  15. Constraints on ocean ridge basalt generation from Gakkel Ridge basalts (United States)

    Langmuir, C. H.; Michael, P.; Standish, J.; Goldstein, S.


    The Gakkel Ridge that traverses the Arctic Ocean from Greenland to Siberia provides five "natural experiments" with respect to our understanding of melt generation and delivery at ocean ridges. (1) It is the deepest of the ocean ridges, and tests the global correlations of basalt chemistry with axial depth and the origin of such correlations. (2) It is the slowest spreading ridge, and tests the influence of ultra-slow spreading on magma generation without the complexity of oblique spreading or multiple transform offsets. (3) The samples are both on- and off-axis, allowing tests of the similarity of on- and off-axis volcanism. (4) It provides a test of the veined mantle disequilibrium melting hypothesis for MORB, since both ultra-slow spreading rate and great depth suggest minimum extents of melting, with the extent of melting decreasing progressively towards the east. (5) It tests segmentation models, because there are no transform offsets along the ridge, and the slow spreading rates should lead to maximum melt focusing along strike. The comprehensive major element, trace element and isotopic data set for the rocks obtained on the AMORE cruise allows investigation of all of these issues. (1) The Gakkel fits global depth-chemistry correlations, and major and trace element data as well as crustal thickness suggest small extents of melting in this region, decreasing towards the east. (2)Ultra-slow spreading leads to a thicker lithospheric lid and more garnet influence towards the east. The effects of thick lithosphere and mantle temperature on melting can be clearly distinguished in this region, and contrast with global systematics. This suggests that lithosphere variations are of minor importance in controlling the global array. (3) Off-axis samples are more diverse than on-axis samples, confirming the importance of off-axis volcanism at ultra-slow ridges. (4) Trace element data do not show an increase in a "veined component" towards the east as spreading rate

  16. Icelandic basaltic geothermal field: A natural analog for nuclear waste isolation in basalt

    International Nuclear Information System (INIS)

    Ulmer, G.C.; Grandstaff, D.E.


    Analog studies of Icelandic geothermal fields have shown that the design of nuclear waste repositories in basalt can benefit by comparison to the data base already available from the development of these geothermal fields. A high degree of similarity exists between these two systems: their petrology, groundwater geochemistry, mineral solubilities, hydrologic parameters, temperature ranges, water-rock redox equilibria, hydrothermal pH values, and secondary mineralogies all show considerable overlap in the range of values. The experimentally-simulated hydrothermal studies of the basaltic nuclear waste repository rocks have, at this time, produced a data base that receives a strong confirmation from the Icelandic analog. Furthermore, the Icelandic analog should eventually be employed to extrapolate into higher and lower temperatures, into longer time-base chemical comparisons, and into more realistic mineral deposition studies, than have been possible in the laboratory evaluations of the nuclear waste repository designs. This eventual use of the Icelandic analog will require cooperative work with the Icelandic Geological Survey. 46 refs., 4 figs., 2 tabs

  17. Marine ecosystem responses to Cenozoic global change. (United States)

    Norris, R D; Turner, S Kirtland; Hull, P M; Ridgwell, A


    The future impacts of anthropogenic global change on marine ecosystems are highly uncertain, but insights can be gained from past intervals of high atmospheric carbon dioxide partial pressure. The long-term geological record reveals an early Cenozoic warm climate that supported smaller polar ecosystems, few coral-algal reefs, expanded shallow-water platforms, longer food chains with less energy for top predators, and a less oxygenated ocean than today. The closest analogs for our likely future are climate transients, 10,000 to 200,000 years in duration, that occurred during the long early Cenozoic interval of elevated warmth. Although the future ocean will begin to resemble the past greenhouse world, it will retain elements of the present "icehouse" world long into the future. Changing temperatures and ocean acidification, together with rising sea level and shifts in ocean productivity, will keep marine ecosystems in a state of continuous change for 100,000 years.

  18. Application of the iron-enriched basalt waste form for immobilizing commercial transuranic waste

    International Nuclear Information System (INIS)

    Owen, D.E.


    The principal sources of commercial transuranic (TRU) waste in the United States are identified. The physical and chemical nature of the wastes from these sources are discussed. The fabrication technique and properties of iron-enriched basalt, a rock-like waste form developed for immobilizing defense TRU wastes, are discussed. The application of iron-enriched basalt to commercial TRU wastes is discussed. Review of commercial TRU wastes from mixed-oxide fuel fabrication, light water reactor fuel reprocessing, and miscellaneous medical, research, and industrial sources, indicates that iron-enriched basalt is suitable for most types of commercial TRU wastes. Noncombustible TRU wastes are dissolved in the high temperature, oxidizing iron-enriched basalt melt. Combustible TRU wastes are immobilized in iron-enriched basalt by incinerating the wastes and adding the TRU-bearing ash to the melt. Casting and controlled cooling of the melt produces a devitrified, rock-like iron-enriched basalt monolith. Recommendations are given for testing the applicability of iron-enriched basalt to commercial TRU wastes

  19. Quaternary Basanitic Rocks within the Eastern Anatolian Volcanism (Turkey): Petrological and Geochemical Constrains (United States)

    Özdemir, Yavuz; Mercan, Çaǧrı; Oyan, Vural; Atakul-Özdemir, Ayşe


    The Eastern Anatolian Cenozoic continental intraplate volcanism was initiated in Middle Miocene as a result of the convergence between the Arabian and Anatolian plates. The origin of Eastern Anatolian volcanism has been the focus of many petrological studies that have aimed to resolve the relative contributions of asthenospheric mantle and/or lithospheric mantle with/without subduction component in the genesis of magmas that compositionally have many affinities to ocean island basalts (OIB) and volcanic arcs. Volcanism in the region characterized by mainly stratovolcanoes, basaltic lava plateaus and are dominantly spread at the northern parts of Bitlis Pötürge Massif (BPM). Our study focuses on a small scale Quaternary basaltic system that firstly observed within the BPM. The volcanic rocks of our study located 50 km to the south of Lake Van and are basanitic in composition. They exposed along K-G striking tensional fissures and crosscut the Upper unit of the Bitlis Massif. Initial products of the volcanism are scoria fall deposits. Thick basanitic lava flows overly the pyroclastics and formed columnar structures. The basanites are generally fine-grained with phenocrysts of olivine+clinopyroxene. The groundmass is typically of clinopyroxene, olivine and Ti magnetite and Cr spinel with interstitial nepheline. The olivine phenocrysts are typically euhedral to subhedral with Forsterite contents of Fo73-83. Clinopyroxenes are highly calcic and show modest variations in Wo47-52-En34-42-Fs10-15 and are weakly zoned with mg# 89-87 at cores to 86-84 at rims. Nephelines occur as minor minerals within the networks of other groundmass minerals. Ti rich and Fe-Cr spinels occur as inclusions in olivine and clinopyroxenes as well as within the groundmass. LILE and LREE enrichments over HFSE and HREE suggest similarities with magmas generated from enriched mantle sources. EC-AFC modeling of trace element and isotope compositions indicates that assimilation of crustal

  20. Geomechanical testing development for the Basalt Waste Isolation Project

    International Nuclear Information System (INIS)

    Cramer, M.L.; Dischler, S.A.; Erb, D.B.; Berlin, G.T.; Wittreich, C.D.; Bauer, R.E.


    One component of this project is the development of a geomechanical testing program to support repository design, site characterization, and performance assessment requirements. Geomechanics information includes characteristics of the in situ stress field and the mechanical properties of the rock mass. The nature of the basalts at the proposed repository depth of approximately 970 m imposes some relatively unusual requirements on testing methods typically used to assess the stress state and rock mass deformability. The rock mass is closely jointed, with the spacing estimated from vertical boreholes to be in the range of 5 to 10 cm for both vertical and horizontal joint sets. The ambient temperature at depth is about 50 0 C. The rock mass is considered fully saturated. This presentation summarizes the development effort currently under way to support site characterization testing to be conducted at the candidate repository horizon in the Exploratory Shaft Facility. Development activities include hydraulic fracturing, overcoring, flat jack testing, and borehole dilatometer testing

  1. Petrological and Geochemical characterization of central Chihuahua basalts: a possible local sign of rifting activity (United States)

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


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

  2. Characterization and petrologic interpretation of olivine-rich basalts at Gusev Crater, Mars (United States)

    McSween, H.Y.; Wyatt, M.B.; Gellert, Ralf; Bell, J.F.; Morris, R.V.; Herkenhoff, K. E.; Crumpler, L.S.; Milam, K.A.; Stockstill, K.R.; Tornabene, L.L.; Arvidson, R. E.; Bartlett, P.; Blaney, D.; Cabrol, N.A.; Christensen, P.R.; Clark, B. C.; Crisp, J.A.; Des Marais, D.J.; Economou, T.; Farmer, J.D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.; Hamilton, V.E.; Johnson, J. R.; Joliff, B.L.; Klingelhofer, G.; Knudson, A.T.; McLennan, S.; Ming, D.; Moersch, J.E.; Rieder, R.; Ruff, S.W.; Schrorder, C.; de Souza, P.A.; Squyres, S. W.; Wanke, H.; Wang, A.; Yen, A.; Zipfel, J.


    Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric shergottites). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and shergottites appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and shergottites in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times. Copyright 2006 by the American Geophysical Union.

  3. Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Suzette Payne


    This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

  4. Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Suzette Payne


    This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

  5. Rapid Cenozoic Subsidence in the Gulf of Mexico Resulting From Hess Rise Conjugate Subduction (United States)

    Wang, Huilin; Gurnis, Michael; Skogseid, Jakob


    Enigmatic surface deflections occurred in North America starting from the Cretaceous, including the continental-scale drainage reorganization and the long-wavelength subsidence in the Western Interior Seaway. These surface undulations cannot be simply explained by sea level change or flexure loading. Coinciding with the large-scale surface deflection, the Gulf of Mexico (GOM) has an immense Paleocene sediment deposition probably caused by tectonic subsidence. Increasing evidence indicates a distinct seismic anomaly localized in the mantle below the GOM. With geodynamic models, we show that the Hess Rise conjugate coincides with the position of the seismic anomaly. The basalt-eclogite transition in the Hess conjugate can lead to a localized dynamic subsidence in the GOM, which is superimposed on the broad surface deflection caused by the Farallon slab. The Hess conjugate, transformed to eclogite, could tilt the surface southward in the U.S. and help frame the GOM as a main depocenter in the Cenozoic.

  6. Geodynamic controls on the contamination of Cenozoic arc magmas in the southern Central Andes: Insights from the O and Hf isotopic composition of zircon (United States)

    Jones, Rosemary E.; Kirstein, Linda A.; Kasemann, Simone A.; Dhuime, Bruno; Elliott, Tim; Litvak, Vanesa D.; Alonso, Ricardo; Hinton, Richard


    Subduction zones, such as the Andean convergent margin of South America, are sites of active continental growth and crustal recycling. The composition of arc magmas, and therefore new continental crust, reflects variable contributions from mantle, crustal and subducted reservoirs. Temporal (Ma) and spatial (km) variations in these contributions to southern Central Andean arc magmas are investigated in relation to the changing plate geometry and geodynamic setting of the southern Central Andes (28-32° S) during the Cenozoic. The in-situ analysis of O and Hf isotopes in zircon, from both intrusive (granitoids) and extrusive (basaltic andesites to rhyolites) Late Cretaceous - Late Miocene arc magmatic rocks, combined with high resolution U-Pb dating, demonstrates distinct across-arc variations. Mantle-like δ18O(zircon) values (+5.4‰ to +5.7‰ (±0.4 (2σ))) and juvenile initial εHf(zircon) values (+8.3 (±0.8 (2σ)) to +10.0 (±0.9 (2σ))), combined with a lack of zircon inheritance suggests that the Late Cretaceous (∼73 Ma) to Eocene (∼39 Ma) granitoids emplaced in the Principal Cordillera of Chile formed from mantle-derived melts with very limited interaction with continental crustal material, therefore representing a sustained period of upper crustal growth. Late Eocene (∼36 Ma) to Early Miocene (∼17 Ma) volcanic arc rocks present in the Frontal Cordillera have 'mantle-like' δ18O(zircon) values (+4.8‰ (±0.2 (2σ) to +5.8‰ (±0.5 (2σ))), but less radiogenic initial εHf(zircon) values (+1.0 (±1.1 (2σ)) to +4.0 (±0.6 (2σ))) providing evidence for mixing of mantle-derived melts with the Late Paleozoic - Early Mesozoic basement (up to ∼20%). The assimilation of both Late Paleozoic - Early Mesozoic Andean crust and a Grenville-aged basement is required to produce the higher than 'mantle-like' δ18O(zircon) values (+5.5‰ (±0.6 (2σ) to +7.2‰ (±0.4 (2σ))) and unradiogenic, initial εHf(zircon) values (-3.9 (±1.0 (2σ)) to +1.6 (±4.4 (2

  7. Mantle dynamics and basalt petrogenesis (United States)

    Ringwood, A. E.


    Differentiation at mid-ocean ridges generates a layered lithosphere consisting of a basaltic crust, immediately underlain by harzburgite and further underlain by pyrolite which has experienced depletion only of highly incompatible elements. The body forces driving subduction are concentrated mainly in the upper half of the lithosphere which is relatively cool and brittle. During subduction, the lower layer of relatively ductile, slightly depleted pyrolite is stripped off and resorbed into the upper mantle, thereby providing a future source region for MORB magmas. The slab which sinks to ~ 600 km is comprised mainly of differentiated former basalt and harzburgite which undergo a different series of phase transformations to those experienced by mantle pyrolite. In consequence, the former basaltic crust remains denser than surrounding mantle whereas former harzburgite becomes relatively buoyant below the 650 km seismic discontinuity. The resulting non-uniformity in stress distribution causes the slab to buckle at this depth and accrete to form a large, relatively cool ovoid "megalith" of mixed former harzburgite and basaltic crust. Heating of the megalith occurs over 1-2 b.y., leading to partial melting of the former basaltic crust. The resultant liquids contaminate regions of former harzburgite, rendering them fertile in the sense of future capacity to produce basaltic magmas. After thermal equilibration, the newly fertile, former harzburgite becomes buoyant, leading to the separation of diapirs which rise into the upper mantle. Such diapirs rising beneath sub-oceanic lithosphere experience small degrees of partial melting to produce ocean island basalts, mainly of the alkaline suite. Diapirs of fertile former harzburgite rising beneath continents become incorporated into the sub-continental lithosphere. This is a cumulative process and is ultimately responsible for the development of the chemical, physical and isotopic characteristics of the sub

  8. Prokaryotic diversity, distribution, and insights into their role in biogeochemical cycling in marine basalts

    Energy Technology Data Exchange (ETDEWEB)

    Mason, Olivia U.; Di Meo-Savoie, Carol A.; Van Nostrand, Joy D.; Zhou, Jizhong; Fisk, Martin R.; Giovannoni, Stephen J.


    We used molecular techniques to analyze basalts of varying ages that were collected from the East Pacific Rise, 9 oN, from the rift axis of the Juan de Fuca Ridge, and from neighboring seamounts. Cluster analysis of 16S rDNA Terminal Restriction Fragment Polymorphism data revealed that basalt endoliths are distinct from seawater and that communities clustered, to some degree, based on the age of the host rock. This age-based clustering suggests that alteration processes may affect community structure. Cloning and sequencing of bacterial and archaeal 16S rRNA genes revealed twelve different phyla and sub-phyla associated with basalts. These include the Gemmatimonadetes, Nitrospirae, the candidate phylum SBR1093 in the c, andin the Archaea Marine Benthic Group B, none of which have been previously reported in basalts. We delineated novel ocean crust clades in the gamma-Proteobacteria, Planctomycetes, and Actinobacteria that are composed entirely of basalt associated microflora, and may represent basalt ecotypes. Finally, microarray analysis of functional genes in basalt revealed that genes coding for previously unreported processes such as carbon fixation, methane-oxidation, methanogenesis, and nitrogen fixation are present, suggesting that basalts harbor previously unrecognized metabolic diversity. These novel processes could exert a profound influence on ocean chemistry.

  9. Geochemical and petrological considerations about the basalts of upper aluminium in the Fildes Peninsula. (Rei George), Antartica

    International Nuclear Information System (INIS)

    Machado, A.; Fernandes de Lima, E.; Chemale, F.


    Petrographic, geochemical and petrological studies of lower Tertiary basaltic rocks from Fildes Peninsula in Antarctica were made to characterize their source and magmatic evolution. These basaltic rocks have porphyritic, glomeroporphyritic, intergranular and intersertal textures. The phenocrysts are of plagioclase (An), augite, pigeonite and Ti-magnetite. These basaltic rocks have AL O from 16 to 22%, Ni from 6 to 88 ppm, Co from 24 to 33 ppm and Cr from 54 to 123 ppm. Enrichment of Rb. Ba, Sr and LREE with respect to HREE is observed as relative depleted in HFSE is detected. The mass balance realized to understand the evolution of liquid that gave source the different basaltic rocks. Showed that the extracted mineral fractions were 76% of plagioclase, 2% of clinopiroxene and 21% of olivine. The intermediate volcanic rocks of Fildes Peninsula can be explained by cristalization fractionation of a basic liquid. The isotopic dates showed initial rations of Sr/Sr <0,704 and positive values of Nd epsilon. These results are strong support a mantelic source for basaltic rocks of Fildes Peninsula. On basis of geochemical, petrological and isotopic characteristics is possible concluded that these rocks were formed in an island are environment with parcial melting of mantle wedge. (author)

  10. High Iridium concentration of alkaline rocks of Deccan and ...

    Indian Academy of Sciences (India)

    R. Narasimhan, Krishtel eMaging Solutions

    inventory at the KTB (Orth et al 1990; Bhandari et al 1993) is negligible, thus favoring an extrater- restrial source. Apart from tholeiitic basalts, which constitute the bulk (∼99%) of Deccan, numerous though minor regions of alkali basalts, carbonatitic and acidic rocks are known to occur; they have not been analyzed for PGE ...

  11. High Iridium concentration of alkaline rocks of Deccan and ...

    Indian Academy of Sciences (India)

    R. Narasimhan, Krishtel eMaging Solutions

    We report here an unusually high concentration of iridium in some alkali basalts and alkaline rocks of Deccan region having an age of about 65Ma, similar to the age of the Cretaceous-Tertiary boundary. The alkali basalts of Anjar, in the western periphery of Deccan province, have irid- ium concentration as high as 178pg/g ...

  12. Basalt-trachybasalt samples in Gale Crater, Mars

    International Nuclear Information System (INIS)

    Edwards, Peter H.; Anderson, Ryan B.; Dyar, Darby


    The ChemCam instrument on the Mars Science Laboratory (MSL) rover, Curiosity, observed numerous igneous float rocks and conglomerate clasts, reported previously. A new statistical analysis of single-laser-shot spectra of igneous targets observed by ChemCam shows a strong peak at ~55 wt% SiO 2 and 6 wt% total alkalis, with a minor secondary maximum at 47–51 wt% SiO 2 and lower alkali content. The centers of these distributions, together with the rock textures, indicate that many of the ChemCam igneous targets are trachybasalts, Mg# = 27 but with a secondary concentration of basaltic material, with a focus of compositions around Mg# = 54. We suggest that all of these igneous rocks resulted from low-pressure, olivine-dominated fractionation of Adirondack (MER) class-type basalt compositions. This magmatism has subalkaline, tholeiitic affinities. The similarity of the basalt endmember to much of the Gale sediment compositions in the first 1000 sols of the MSL mission suggests that this type of Fe-rich, relatively low-Mg#, olivine tholeiite is the dominant constituent of the Gale catchment that is the source material for the fine-grained sediments in Gale. The similarity to many Gusev igneous compositions suggests that it is a major constituent of ancient Martian magmas, and distinct from the shergottite parental melts thought to be associated with Tharsis and the Northern Lowlands. Finally, the Gale Crater catchment sampled a mixture of this tholeiitic basalt along with alkaline igneous material, together giving some analogies to terrestrial intraplate magmatic provinces.

  13. Evidence for subduction-related magmatism during the Cretaceous and Cenozoic in Myanmar (United States)

    Sevastjanova, Inga; Sagi, David Adam; Webb, Peter; Masterton, Sheona; Hill, Catherine; Davies, Clare


    Myanmar's complex geological history, numerous controversies around its tectonic evolution and the presence of prospective hydrocarbon basins make it a key area of interest for geologists. Understanding whether a passive or an active margin existed in the region during the Cenozoic is particularly important for the production of accurate basin models; active Cenozoic subduction would imply that hydrocarbon basins in the forearc experienced extension due to slab rollback. The geology of Myanmar was influenced by the regional tectonics associated with the Cretaceous and Cenozoic closure of the Neotethys Ocean. During this time, India travelled rapidly from Gondwana to Asia at speeds up to 20 cm/yr. To accommodate the north-eastward motion of India, the Neotethys Ocean was consumed at the subduction zone along the southern margin of Eurasia. Based on our Global Plate Model, this subduction zone can reasonably be expected to extend for the entire width of the Neotethys Ocean as far as Myanmar and Southeast Asia at their eastern extent. Moreover, a) Cretaceous volcanism onshore Myanmar, b) the middle Cenozoic arc-related extension in the Present Day eastern Andaman Sea and c) the late Cenozoic uplift of the Indo-Burman Ranges are all contemporaneous with the subduction ages predicted by the global plate motions. However, because of the geological complexity of the area, additional evidence would augment interpretations that are based on structural data. In an attempt to reduce the uncertainty in the existing interpretations, we have compiled published zircon geochronological data from detrital and igneous rocks in the region. We have used published zircon U-Pb ages and, where available, published Hf isotope data and CL images (core/rim) in order to distinguish 'juvenile' mantle-derived zircons from those of reworked crustal origin. The compilation shows that Upper Cretaceous and Cenozoic zircons, which are interpreted to have a volcanic provenance, are common across the

  14. Triple junction magmatism: a geochemical study of Neogene volcanic rocks in western California (United States)

    Johnson, C.M.; O'Neil, J.R.


    of the subducted slab at a transform-transform-trench triple junction might promote passive upwelling of mantle material to fill it and induce melting to generate basalts. Mafic volcanic rocks of this origin may provide a unique view of the subcontinental mantle at the continental margin. 87Sr 86Sr ratios as low as 0.70255 for mafic volcanic rocks in the Sonoma-Tolay center associated with the MTJ contrast with high La Sm ratios of 1.1 to 1.3 and low Zr Nb, Hf Ta, La Th, and La Ta ratios of 5.0 to 6.7, 2.6 to 3.5, 4.7 to 8.8, and 10.2 to 12.5, respectively. These data suggest that the mantle beneath parts of western California may have originally been depleted but has been enriched relatively recently. Such enrichment might have occurred by metasomatic processes associated with crustal accretion and/or juxtaposition of differing lithospheric mantle in the Mesozoic and Cenozoic. ?? 1984.

  15. Modulation of Cenozoic climate by weathering of large igneous provinces on continents drifting through equatorial humid belt (United States)

    Muttoni, G.; Kent, D. V.


    The small reservoir of CO2 in the atmosphere (pCO2) that modulates climate through the greenhouse effect is a delicate balance between large fluxes of sources and sinks. The major long-term source of CO2 is global degassing from sea-floor spreading, subduction, hotspot activity, and metamorphism; the ultimate sink is through weathering of continental silicates. Most carbon cycle models are driven by changes in the source flux, in particular, variable rates of ocean floor production (and concomitant subduction) but the area/age versus age distribution of the modern ocean is compatible with a steady rate since 180 Ma (Rowley, 2002 GSA Bulletin). We previously suggested (2008 PNAS) that evidence of high pCO2 and warm climates in the Cretaceous-early Cenozoic could be explained by the subduction of Tethyan ocean crust loaded with equatorial carbonate-rich pelagic (more readily subductable) sediments since the onset of India's northward flight at ~120 Ma up until the CO2-producing decarbonation factory slowed down with collision of India and Asia at the Early Eocene Climate Optimum at 50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO2 by efficient silicate weathering would further lower the level of pCO2. Continued weathering uptake was influenced by the southerly extrusion of SE Asia in response to the Indian indentor starting at ~40 Ma (Molnar & Tapponnier, 1975 Science) as well as the emplacement of the Ethiopian traps near the Equator at 30 Ma. The ongoing impingement of India into Asia and resultant southerly tectonic extrusion of SE Asia (Replumaz & Tapponnier, 2003 JGR) makes it the dominant new area in the equatorial humid belt. Moreover, SE Asia presently accounts for 25% of CO2 consumption of all basaltic provinces, which account for ~1/3 of the total consumption by continental silicate weathering (Dessert et al., 2003 Chemical Geology) that is within the range of

  16. Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

    Directory of Open Access Journals (Sweden)

    al-Swaidani Aref M.


    Full Text Available The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction. Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289 and accelerated mortar bar test (ASTM C1260 have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida’a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete.

  17. Cenozoic exhumation history of South China: A case study from the Xuefeng Mt. Range (United States)

    Wang, Yannan; Zhang, Jin; Zhang, Beihang; Zhao, Heng


    New apatite fission track (AFT) dating was applied to the Xuefeng Mt. Range and Yuanma Basin to constrain the Cenozoic exhumation process of the southeastern Yangtze Block, South China. The analyzed samples in this study have AFT ages ranging from 27.9 ± 2.5 to 61.5 ± 5.9 Ma, which are younger than the deposition or crystallization ages of the host rocks. The AFT analysis and thermal history modeling indicate that both the Xuefeng Mt. Range and the Yuanma Basin underwent significant exhumation during the early Cenozoic (ca. 60-40 Ma). These samples were rapidly exhumed to near the surface during this period. Our results suggest that an important tectonic event occurred along or near regional fault zones (e.g., the Qinhang Fault) in South China during the early Cenozoic (ca. 60-40 Ma). However, it is difficult to relate this event to the Eastern Sichuan fold belt, which is much older and is characterized by large-scale folding and thrusting. Combined with fieldwork in the Yuanma, Xupu, and Xinning basins, we refute the Cretaceous "Pan-Yangtze Basin" that was proposed to have been separated by the uplifted Xuefeng Mt. Range after the Late Cretaceous. The exhumation stage from ca. 60 Ma to 40 Ma was an important period during which plate movements across the eastern Asian and Pacific regions were reorganized. The early Cenozoic tectonothermal event in South China can be attributed to a change in the direction and speed of the subduction of the Pacific Plate beneath the Eurasian Plate. An Oligocene-Miocene cooling event was also recorded in the eastern Xuefeng Mt. Range, which we tentatively attribute to the activity of dextral faults in this area as a far-field effect of the collision between the Indian and Eurasian plates.

  18. Continental erosion and the Cenozoic rise of marine diatoms. (United States)

    Cermeño, Pedro; Falkowski, Paul G; Romero, Oscar E; Schaller, Morgan F; Vallina, Sergio M


    Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive ability for silicic acid relative to other siliceous plankton such as radiolarians, which evolved by reducing the weight of their silica test. Here we use a mathematical model in which diatoms and radiolarians compete for silicic acid to show that the observed reduction in the weight of radiolarian tests is insufficient to explain the rise of diatoms. Using the lithium isotope record of seawater as a proxy of silicate rock weathering and erosion, we calculate changes in the input flux of silicic acid to the oceans. Our results indicate that the long-term massive erosion of continental silicates was critical to the subsequent success of diatoms in marine ecosystems over the last 40 My and suggest an increase in the strength and efficiency of the oceanic biological pump over this period.

  19. Basalt Pb isotope analysis and the prehistoric settlement of Polynesia. (United States)

    Weisler, M I; Woodhead, J D


    The prehistoric settlement of the Pacific Ocean has intrigued scholars and stimulated anthropological debate for the past two centuries. Colonized over a few millennia during the mid to late Holocene, the islands of the Pacific--displaying a wide diversity of geological and biotic variability--provided the stage for endless "natural experiments" in human adaptation. Crucial to understanding the evolution and transformation of island societies is documenting the relative degree of interisland contacts after island colonization. In the western Pacific, ideal materials for archaeologically documenting interisland contact--obsidian, pottery, and shell ornaments--are absent or of limited geographic distribution in Polynesia. Consequently, archaeologists have relied increasingly on fine-grained basalt artifacts as a means for documenting colonization routes and subsequent interisland contacts. Routinely used x-ray fluorescence characterization of oceanic island basalt has some problems for discriminating source rocks and artifacts in provenance studies. The variation in trace and major element abundances is largely controlled by near-surface magma-chamber processes and is broadly similar between most oceanic islands. We demonstrate that Pb isotope analysis accurately discriminates rock source and is an excellent technique for charting the scale, frequency, and temporal span of imported fine-grained basalt artifacts found throughout Polynesia. The technique adds another tool for addressing evolutionary models of interaction, isolation, and cultural divergence in the eastern Pacific. PMID:7892194

  20. Cenozoic stratigraphy of the Sahara, Northern Africa (United States)

    Swezey, Christopher S.


    This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the

  1. Cenozoic extensional tectonics of the Western Anatolia Extended Terrane, Turkey

    International Nuclear Information System (INIS)

    Cemen, I; Catlos, E J; Gogus, O; Diniz, E; Hancer, M


    The Western Anatolia Extended Terrane in Turkey is located on the eastern side of the Aegean Extended Terrane and contains one of the largest metamorphic core complexes in the world, the Menderes massif. It has experienced a series of continental collisions from the Late Cretaceous to the Eocene during the formation of the Izmir-Ankara-Erzincan suture zone. Based our field work and monazite ages, we suggest that the north-directed postcollisional Cenozoic extension in the region is the product of three consecutive stages, triggered by three different mechanisms. The first stage was initiated about 30 Ma ago, in the Oligocene by the Orogenic Collapse the thermally weakened continental crust along the north-dipping Southwest Anatolian shear zone. The shear zone was formed as an extensional simple-shear zone with listric geometry at depth and exhibits predominantly normal-slip along its southwestern end. But, it becomes a high-angle oblique-slip shear zone along its northeastern termination. Evidence for the presence of the shear zone includes (1) the dominant top to the north-northeast shear sense indicators throughout the Menderes massif, such as stretching lineations trending N10E to N30E; and (2) a series of Oligocene extensional basins located adjacent to the shear zone that contain only carbonate and ophiolitic rock fragments, but no high grade metamorphic rock fragments. During this stage, erosion and extensional unroofing brought high-grade metamorphic rocks of the Central Menderes massif to the surface by the early Miocene. The second stage of the extension was triggered by subduction roll-back and associated back-arc extension in the early Miocene and produced the north-dipping Alasehir and the south-dipping Bueyuek Menderes detachments of the central Menderes massif and the north-dipping Simav detachment of the northern Menderes massif. The detachments control the Miocene sedimentation in the Alasehir, Bueyuek Menderes, and Simav grabens, containing high

  2. Cenozoic extensional tectonics of the Western Anatolia Extended Terrane, Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Cemen, I; Catlos, E J [Boone Pickens School of Geology, Oklahoma State University, 105 Noble Research Center, Stillwater OK 74078 (United States); Gogus, O [University of Toronto, Department of Geology, Earth Sciences Centre, 22 Russell St. Toronto, Ontario, M5S 3B1 (Canada); Diniz, E [Occidental Oil and Gas Corporation, PO Box 22757, Houston TX 77227 (United States); Hancer, M [Pamukkale Universitesi, Muhendislik Fakultesi, Jeoloji Muh. Bolmu, Denizli, 20070 Turkey (Turkey)], E-mail:


    The Western Anatolia Extended Terrane in Turkey is located on the eastern side of the Aegean Extended Terrane and contains one of the largest metamorphic core complexes in the world, the Menderes massif. It has experienced a series of continental collisions from the Late Cretaceous to the Eocene during the formation of the Izmir-Ankara-Erzincan suture zone. Based our field work and monazite ages, we suggest that the north-directed postcollisional Cenozoic extension in the region is the product of three consecutive stages, triggered by three different mechanisms. The first stage was initiated about 30 Ma ago, in the Oligocene by the Orogenic Collapse the thermally weakened continental crust along the north-dipping Southwest Anatolian shear zone. The shear zone was formed as an extensional simple-shear zone with listric geometry at depth and exhibits predominantly normal-slip along its southwestern end. But, it becomes a high-angle oblique-slip shear zone along its northeastern termination. Evidence for the presence of the shear zone includes (1) the dominant top to the north-northeast shear sense indicators throughout the Menderes massif, such as stretching lineations trending N10E to N30E; and (2) a series of Oligocene extensional basins located adjacent to the shear zone that contain only carbonate and ophiolitic rock fragments, but no high grade metamorphic rock fragments. During this stage, erosion and extensional unroofing brought high-grade metamorphic rocks of the Central Menderes massif to the surface by the early Miocene. The second stage of the extension was triggered by subduction roll-back and associated back-arc extension in the early Miocene and produced the north-dipping Alasehir and the south-dipping Bueyuek Menderes detachments of the central Menderes massif and the north-dipping Simav detachment of the northern Menderes massif. The detachments control the Miocene sedimentation in the Alasehir, Bueyuek Menderes, and Simav grabens, containing high

  3. Cenozoic extensional tectonics of the Western Anatolia Extended Terrane, Turkey (United States)

    Çemen, I.; Catlos, E. J.; Gogus, O.; Diniz, E.; Hancer, M.


    The Western Anatolia Extended Terrane in Turkey is located on the eastern side of the Aegean Extended Terrane and contains one of the largest metamorphic core complexes in the world, the Menderes massif. It has experienced a series of continental collisions from the Late Cretaceous to the Eocene during the formation of the Izmir-Ankara-Erzincan suture zone. Based our field work and monazite ages, we suggest that the north-directed postcollisional Cenozoic extension in the region is the product of three consecutive stages, triggered by three different mechanisms. The first stage was initiated about 30 Ma ago, in the Oligocene by the Orogenic Collapse the thermally weakened continental crust along the north-dipping Southwest Anatolian shear zone. The shear zone was formed as an extensional simple-shear zone with listric geometry at depth and exhibits predominantly normal-slip along its southwestern end. But, it becomes a high-angle oblique-slip shear zone along its northeastern termination. Evidence for the presence of the shear zone includes (1) the dominant top to the north-northeast shear sense indicators throughout the Menderes massif, such as stretching lineations trending N10E to N30E; and (2) a series of Oligocene extensional basins located adjacent to the shear zone that contain only carbonate and ophiolitic rock fragments, but no high grade metamorphic rock fragments. During this stage, erosion and extensional unroofing brought high-grade metamorphic rocks of the Central Menderes massif to the surface by the early Miocene. The second stage of the extension was triggered by subduction roll-back and associated back-arc extension in the early Miocene and produced the north-dipping Alaşehir and the south-dipping Büyük Menderes detachments of the central Menderes massif and the north-dipping Simav detachment of the northern Menderes massif. The detachments control the Miocene sedimentation in the Alaşehir, Büyük Menderes, and Simav grabens, containing high

  4. Geomechanics laboratory characterization of borehole RRL-2 rock core

    International Nuclear Information System (INIS)

    Sublette, W.R.


    A series of geomechanics laboratory tests were conducted on the basalt core from borehole RRL-2 for the purpose of characterizing the basalt with respect to its physical, mechanical, and thermal properties. The objectives of this testing were to characterize the basalt properties in the area of the proposed shaft and repository site. These rock properties will be used in designing the Exploratory Shaft, evaluating basalt drillability, selecting the Exploratory Shaft breakout horizon, and developing a repository upgraded conceptual design. 10 refs., 1 fig., 6 tabs

  5. U-Pb zircon geochronology and geochemistry of Late Jurassic basalts in Maevatanana, Madagascar: Implications for the timing of separation of Madagascar from Africa (United States)

    Yang, Xi-An; Chen, Yu-Chuan; Hou, Ke-Jun; Liu, Shan-Bao; Liu, Jia-Jun


    Magmatic zircon ages for the Maevatanana basalts in Madagascar indicate that Madagascar separated from Africa at 149.8 ± 2.1 Ma. Rocks produced by this basaltic magmatism associated with rifting are characterized by low SiO2 (49.6-50.3 wt.%), high total FeO (>13.9 wt.%), TiO2 (>3.7 wt.%), and P2O5 (>0.5 wt.%), and extremely high Na2O/K2O (3.08-3.27). Geochemical variations can be ascribed to significant fractional crystallization of clinopyroxene and plagioclase. The mineralogical and geochemical characteristics of the Maevatanana basalts suggest affinities with calc-alkaline basalt. Additionally the basalts have distinct ocean-island-basalt-like geochemical features that may be related to the Marion plume. We speculate that the Maevatanana basalts are the product of the Marion mantle plume related to separation of Madagascar from Africa in the Late Jurassic.

  6. Preliminary geologic map of the late Cenozoic sediments of the western half of the Pasco Basin

    International Nuclear Information System (INIS)

    Lillie, J.T.; Tallman, A.M.; Caggiano, J.A.


    The U.S. Department of Energy, through the Basalt Waste Isolation Program within the Rockwell Hanford Operations, is investigating the feasibility of terminal storage of radioactive waste in deep caverns constructed in Columbia River Basalt. This report represents a portion of the geological work conducted during fiscal year 1978 to assess the geological conditions in the Pasco Basin. The surficial geology of the western half of the Pasco Basin was studied and mapped in a reconnaissance fashion at a scale of 1:62,500. The map was produced through a compilation of existing geologic mapping publications and additional field data collected during the spring of 1978. The map was produced primarily to: (1) complement other mapping work currently being conducted in the Pasco Basin and in the region by Rockwell Hanford Operations and its subcontractors; and, (2) to provide a framework for more detailed late Cenozoic studies within the Pasco Basin. A description of procedures used to produce the surficial geologic map and geologic map units is summarized in this report

  7. The change of magma chamber depth in and around the Baekdu Volcanic area from late Cenozoic (United States)

    Lee, S. H.; Oh, C. W.; Lee, Y. S.; Lee, S. G.; Liu, J.


    The Baekdu Volcano is a 2750m high stratovolcanic cone resting on a basaltic shield and plateau and locates on the North Korea-China border. Its volcanic history can be divided into four stages (from the oldest to the youngest): (i) preshield plateau-forming eruptions, (ii) basalt shield formation, (iii) construction of a trachytic composite cone, and (iv) explosive ignimbrite forming eruptions. In the First stage, a fissure eruption produced basalts from the Oligocene to the Miocene (28-13 Ma) forming preshield plateau. Fissure and central eruptions occurred together during the shield-forming eruptions (4.21-1.70 Ma). In the third stage, the trachytic composite volcano formed during the Pleistocene (0.61-0.09 Ma). In this stage, magma changed to an acidic melt. The latest stage has been characterized by explosive ignimbrite-forming eruptions during the Holocene. The composite volcanic part consists of the Xiaobaishan, Lower, Middle and Upper Trachytes with rhyolites. The whole rock and clinopyroxene in basalts, trachytic and rhyolite, are analyzed to study the depth of magma chambers under the Baekdu Volcano. From the rhyolite, 9.8-12.7kbar is obtained for the depth of magma chamber. 3.7-4.1, 8.9-10.5 and 8.7 kbar are obtained from the middle, lower and Xiaobaishan trachytes. From the first and second stage basalts, 16.9-17.0 kbar and 14-14.4kbar are obtained respectively. The first stage basalt give extrusive age of 11.98 Ma whereas 1.12 and 1.09 Ma are obtained from the feldspar and groundmass in the second stage basalt. The Xiaobaishan trachyte and rhyolite give 0.25 and 0.21 Ma whereas the Middle trachyte gives 0.07-0.06 Ma. These data indicate that the magma chambers of the first and second stage basalts were located in the mantle and the magma chamber for the second stage basalt may have been underplated below continental crust. The Xiaobisan trachyte and rhyolite originated from the magma chamber in the depth of ca. 30-40 km and the Middle trachyte

  8. Origin of sapphirine- and garnet-bearing clinopyroxenite xenoliths entrained in the Jiande basalts, SE China (United States)

    Xiao, Yan; Zhang, Hong-Fu; Liang, Zi; Su, Ben-Xun; Zhu, Bin; Sakyi, Patrick Asamoah


    We present petrological and geochemical data of sapphirine- and garnet-bearing clinopyroxenite xenoliths entrained in the Jiande Cenozoic basalts, SE China, to investigate their igneous and metamorphic history, and reconstruct of the thermal-tectonic evolution of the lithospheric mantle. These xenoliths have an unusual mineral association consisting of clinopyroxene + garnet/kelyphite + spinel (±sapphirine). Clinopyroxene has high Mg# (89-93) and displays convex-upward REE pattern. Garnet, partially to completely kelyphitized, is rich in pyrope end-member. It usually includes relics of spinel, suggesting that garnet was formed at the expense of spinel. The spinel has high MgO (20.8-22.9 wt%) and Al2O3 (64.8-67.9 wt%) contents. Sapphirine, forming a rim on spinel, has homogeneous SiO2 (14.5-14.9 wt%), Al2O3 (60.9-61.7 wt%) and MgO (19.7-20.1 wt%) contents, interpreted to be of metamorphic origin. The subsolidus reaction for the formation of sapphirine is as follows: spinel + garnet = sapphirine + clinopyroxene + orthopyroxene. Thus, the earliest mineral assemblage recorded in these xenoliths was spinel + clinopyroxene. The clinopyroxene in the Jiande clinopyroxenite xenoliths has Li abundances (1.04-1.63 ppm) similar to high-P mafic cumulate but much lower than those in crustal eclogite. In addition, the clinopyroxene and garnet do not show positive Eu anomalies. Therefore, the protolith of these three clinopyroxenite xenoliths was most likely a pyroxenite, originating as clinopyroxene + spinel cumulates from mafic melts percolating through the mantle. Many reaction textures such as formation of garnet and sapphirine were developed during decompression possibly coupled with cooling and melt percolation. During this process, the earlier composition of clinopyroxene and spinel also changed. The latest P-T conditions recorded in these xenoliths were at pressure of 8-10 kbar and temperatures of 1069-1094 °C. These observations imply that these rocks have been

  9. Giant Plagioclase Basalts, eruption rate versus time

    Indian Academy of Sciences (India)

    R.Narasimhan(krishtel emaging) 1461 1996 Oct 15 13:05:22

    can traps; Earth Planet. Sci. Lett. 180 13–27. Hooper P R and others 1988 The Giant Plagioclase Basalts. (GPBs) of the Western Ghats, Deccan Traps; Mem. Geol. Soc. India 43 153–65. Khadri S F R and 3 others 1988 Stratigraphy of Thakurvadi. Formation, Western Deccan Basalt Province, India: In. Deccan Flood Basalts ...

  10. Evidence of proterozoic crust under the coastal Cordillera of Central Chile: Grenville age xenocrystic zircons in cretaceous volcanic rocks

    International Nuclear Information System (INIS)

    Zentilli, M; Pop, N; Heaman; L; Boric, R


    In the central Andes, Proterozoic basement rocks outcrop in isolated areas from beneath a Mesozoic and Cenozoic cover in southern Peru, northernmost Chile, Bolivia, and in northwestern Argentina. Their role in Andean magmatism and metallogenesis is well documented. In the southern Central Andes, Proterozoic rocks are so far known to outcrop in Argentina, east of the continental divide. In the course of U-Pb dating of the bimodal volcanic and sub-volcanic host rocks for Mesozoic manto-type copper deposits, we have encountered xenocrystic zircon with Proterozoic and Paleozoic ages. In the Punta del Cobre Cu-Fe (Au) District (27 o 30' S / 70 o 15' W) 22 km south of Copiapo xenocrystic zircon in the Lower Cretaceous host dacite yields ca. 1 Ga ages. In the El Soldado Cu District, (32 o 38' S /71 o 04' W), 120 km northwest of Santiago, scarce and strongly resorbed zircon crystals in the Lower Cretaceous host rhyodacite yield ages of 0.5 to 1.3 Ga. The early Cretaceous bimodal volcanic and subvolcanic rocks, which consists of primitive calc-alkaline basalts and rhyodacites, display geochemical evidence of crustal contamination. Our results suggest that, during their formation and ascent, the felsic magmas picked up zircons in the Proterozoic and Paleozoic crystalline basement of the Coastal Cordillera. The presence of Proterozoic (Grenville age) basement underlying localities as close as 30 km from the Pacific coast has implications for the extent and age of the Chilenia Terrane and gives further credence to correlation models that juxtapose eastern North America (Laurentia) and southwestern South America (Gondwana) during the Late Proterozoic (au)

  11. Petrology of basaltic and monomineralic soil fragments from the Sea of Fertility. (United States)

    Bence, A. E.; Holzwarth, W.; Papike, J. J.


    Basaltic and monomineralic fragments from the 150-425 micron size fractions of the Luna 16 core obtained from the Sea of Fertility were studied by optical petrographic, electron microprobe, and single-crystal X-ray diffraction techniques. Three textural varieties were identified in the basalts (intersertal, subophitic, and recrystallized). These textures, the assemblages, and individual mineral compositions (especially pyroxenes) indicate that these basalts crystallized under conditions very similar to those from Apollo 11. The pyroxenes have slightly lower Ti/Al (atomic) ratios than the Apollo 11 pyroxenes. We interpret the presence of octahedral Al as being due to the low TiO2/Al2O3 (weight %) ratio in the bulk rock. All observations made on the fine-grained basalt fragments are consistent with a rapid, near-surface, one-stage crystallization history.

  12. Experimental investigation of the reaction between corundum xenocrysts and alkaline basaltic host magma: Constraints on magma residence times of basalt-hosted sapphires (United States)

    Baldwin, L. C.; Ballhaus, C.


    Megacrystic sapphires (Fe-Ti-rich corundum) of up to 5 cm in size are well known from alkaline mafic rocks from intra-continental rift-related magmatic fields. There is no doubt that these sapphires represent xenocrysts that were trapped from their original lithology by ascending basaltic magmas carrying them to the Earth's surface. Most studies about basalt-hosted sapphires address the question about the origin of the sapphires, but there is hardly any information available about the time the sapphires resided inside the carrier melt. Sapphires are in reaction relationship with basalt and produce spinel coronas at the sapphire-basalt interface, spatially separating the mutually incompatible phases from one another. Assuming isothermal and isobaric conditions of spinel rim formation, the rim-thickness should be a function of the reaction time with the basaltic melt. In this paper, we report time-series experiments aimed at investigating the kinetics of spinel rim formation due to igneous corrosion of corundum. Therefore, we reacted corundum fragments with alkaline basalt powder at 1250 °C and 1GPa, using a Piston Cylinder Apparatus. The width of the spinel rim was used to estimate a residence time. Extrapolating the experimentally derived reaction rates to the thickness of natural spinel rims as described from the Siebengebirge Volcanic Field, Germany, and from Changle, China, we estimated residence times in the order of a few weeks to months.

  13. Gas cluster ion beam for the characterization of organic materials in submarine basalts as Mars analogs

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Naoko, E-mail:; Barlow, Anders J.; Cumpson, Peter J. [National EPSRC XPS Users' Service (NEXUS), School of Mechanical and Systems Engineering, Stephenson Building, Newcastle University, Newcastle-upon-Tyne NE1 7RU (United Kingdom); Purvis, Graham W. H.; Abbott, Geoffrey D.; Gray, Neil N. D. [School of Civil Engineering and Geosciences, Devonshire Building, Newcastle University, Newcastle-upon-Tyne NE1 7RU (United Kingdom)


    The solar system contains large quantities of organic compounds that can form complex molecular structures. The processing of organic compounds by biological systems leads to molecules with distinctive structural characteristics; thus, the detection and characterization of organic materials could lead to a high degree of confidence in the existence of extra-terrestrial life. Given the nature of the surface of most planetary bodies in the solar system, evidence of life is more likely to be found in the subsurface where conditions are more hospitable. Basalt is a common rock throughout the solar system and the primary rock type on Mars and Earth. Basalt is therefore a rock type that subsurface life might exploit and as such a suitable material for the study of methods required to detect and analyze organic material in rock. Telluric basalts from Earth represent an analog for extra-terrestrial rocks where the indigenous organic matter could be analyzed for molecular biosignatures. This study focuses on organic matter in the basalt with the use of surface analysis techniques utilizing Ar gas cluster ion beams (GCIB); time of flight secondary ion mass spectrometry (ToF-SIMS), and x-ray photoelectron spectroscopy (XPS), to characterize organic molecules. Tetramethylammonium hydroxide (TMAH) thermochemolysis was also used to support the data obtained using the surface analysis techniques. The authors demonstrate that organic molecules were found to be heterogeneously distributed within rock textures. A positive correlation was observed to exist between the presence of microtubule textures in the basalt and the organic compounds detected. From the results herein, the authors propose that ToF-SIMS with an Ar GCIB is effective at detecting organic materials in such geological samples, and ToF-SIMS combined with XPS and TMAH thermochemolysis may be a useful approach in the study of extra-terrestrial organic material and life.

  14. Gas cluster ion beam for the characterization of organic materials in submarine basalts as Mars analogs

    International Nuclear Information System (INIS)

    Sano, Naoko; Barlow, Anders J.; Cumpson, Peter J.; Purvis, Graham W. H.; Abbott, Geoffrey D.; Gray, Neil N. D.


    The solar system contains large quantities of organic compounds that can form complex molecular structures. The processing of organic compounds by biological systems leads to molecules with distinctive structural characteristics; thus, the detection and characterization of organic materials could lead to a high degree of confidence in the existence of extra-terrestrial life. Given the nature of the surface of most planetary bodies in the solar system, evidence of life is more likely to be found in the subsurface where conditions are more hospitable. Basalt is a common rock throughout the solar system and the primary rock type on Mars and Earth. Basalt is therefore a rock type that subsurface life might exploit and as such a suitable material for the study of methods required to detect and analyze organic material in rock. Telluric basalts from Earth represent an analog for extra-terrestrial rocks where the indigenous organic matter could be analyzed for molecular biosignatures. This study focuses on organic matter in the basalt with the use of surface analysis techniques utilizing Ar gas cluster ion beams (GCIB); time of flight secondary ion mass spectrometry (ToF-SIMS), and x-ray photoelectron spectroscopy (XPS), to characterize organic molecules. Tetramethylammonium hydroxide (TMAH) thermochemolysis was also used to support the data obtained using the surface analysis techniques. The authors demonstrate that organic molecules were found to be heterogeneously distributed within rock textures. A positive correlation was observed to exist between the presence of microtubule textures in the basalt and the organic compounds detected. From the results herein, the authors propose that ToF-SIMS with an Ar GCIB is effective at detecting organic materials in such geological samples, and ToF-SIMS combined with XPS and TMAH thermochemolysis may be a useful approach in the study of extra-terrestrial organic material and life.

  15. Preparation of Basalt Incorporated Polyethylene Composite with Enhanced Mechanical Properties for Various Applications

    Directory of Open Access Journals (Sweden)

    Bredikhin Pavel


    Full Text Available The present article showed the possibility of increasing the complex of mechanical properties of polyolefins with dispersed mineral fillers obtained by fine grinding of basalt rocks via ball mill processing. The composites based on dispersed basalt, which were derived from Samara rock mass (Russia with rare earth elements containing, were obtained by extrusion combining the binder and filler, followed by preparation injection-molded test samples. The study of mechanical properties of materials developed showed the possibility of a significant increase in strength characteristics of different types of polyethylene: the breaking stress at static bending for HDPE can be increasing more than 60% and the impact strength by more than 4 times. In addition the incorporation of the dispersed basalt also enhanced the thermal properties of the composites (the oxygen index of HDPE increases from 19 to 25%.

  16. Cenozoic plant diversity of Yunnan: A review

    Directory of Open Access Journals (Sweden)

    Yongjiang Huang


    Full Text Available Yunnan in southwestern China is renowned for its high plant diversity. To understand how this modern botanical richness formed, it is critical to investigate the past biodiversity throughout the geological time. In this review, we present a summary on plant diversity, floristics and climates in the Cenozoic of Yunnan and document their changes, by compiling published palaeobotanical sources. Our review demonstrates that thus far a total of 386 fossil species of ferns, gymnosperms and angiosperms belonging to 170 genera within 66 families have been reported from the Cenozoic, particularly the Neogene, of Yunnan. Angiosperms display the highest richness represented by 353 species grouped into 155 genera within 60 families, with Fagaceae, Fabaceae, Lauraceae and Juglandaceae being the most diversified. Most of the families and genera recorded as fossils still occur in Yunnan, but seven genera have disappeared, including Berryophyllum, Cedrelospermum, Cedrus, Palaeocarya, Podocarpium, Sequoia and Wataria. The regional extinction of these genera is commonly referred to an aridification of the dry season associated with Asian monsoon development. Floristic analyses indicate that in the late Miocene, Yunnan had three floristic regions: a northern subtropical floristic region in the northeast, a subtropical floristic region in the east, and a tropical floristic region in the southwest. In the late Pliocene, Yunnan saw two kinds of floristic regions: a subalpine floristic region in the northwest, and two subtropical floristic regions separately in the southwest and the eastern center. These floristic concepts are verified by results from our areal type analyses which suggest that in the Miocene southwestern Yunnan supported the most Pantropic elements, while in the Pliocene southwestern Yunnan had abundant Tropical Asia (Indo–Malaysia type and East Asia and North America disjunct type that were absent from northwestern Yunnan. From the late Miocene to

  17. Rb-Sr dating of illite in red rock series

    Energy Technology Data Exchange (ETDEWEB)

    Luo, W.; Weng, J.; Lin, Y.


    The rubidium-strontium isotope ratios in illite were used to determine the age of karst breccias near Guilin, PRC. The radiometric dating was shown to yield values consistent with similar dating of volcanogenic intercalations in other Mesozoic and Cenozoic red rock series.

  18. Delineation of aquifers in basaltic hard rock terrain using vertical ...

    Indian Academy of Sciences (India)

    The region under investigation for groundwater exploration is a part of the eastern fringe of Deccan traps in Kalmeshwar Taluk of Nagpur district. In this region, groundwater is the main source of water supply for drinking and irrigation purposes. Presently, the known source of groundwater is the upper weathered mantle in ...

  19. Delineation of aquifers in basaltic hard rock terrain using vertical ...

    Indian Academy of Sciences (India)

    E longitude, suddenly turn north to join each other before Ghogali. These channels drain out groundwater from the shallow aquifers and thus reduce the availability of ground- water in the dug wells. As a result, majority of dug wells go dry during summer. The present work is aimed to delineate intertrappeans and fracture.

  20. Delineation of aquifers in basaltic hard rock terrain using vertical ...

    Indian Academy of Sciences (India)

    carried out integrated geophysical surveys consist- ing of VES and magnetic surveys for groundwater exploration in Deccan traps covered the Godavari–. Purana basin in Aurangabad district of Maharashtra. Murthy et al. (1986) have delineated Gondwana formation below the Deccan traps in Umrer,. Bander, Kamathi and ...

  1. Rock Pore Structure as Main Reason of Rock Deterioration

    Directory of Open Access Journals (Sweden)

    Ondrášik Martin


    Full Text Available Crashed or dimensional rocks have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material - concrete includes large amounts of crashed rock, especially limestone, dolostone and andesite.

  2. Studies of Magmatic Inclusions in the Basaltic Martian Meteorites Shergotty, Zagami, EETA 79001 and QUE 94201 (United States)

    Harvey, Ralph P.; McKay, Gordon A.


    Currently there are 12 meteorites thought by planetary scientists to be martian samples, delivered to the Earth after violent impacts on that planet's surface. Of these 12 specimens, 4 are basaltic: Shergotty, Zagami, EETA 79001 and QUE 94201. Basalts are particularly important rocks to planetary geologists- they are the most common rocks found on the surfaces of the terrestrial planets, representing volcanic activity of their parent worlds. In addition, because they are generated by partial melting of the mantle and/or lower crust, they can serve as guide posts to the composition and internal processes of a planet. Consequently these four meteorites can serve as 'ground-truth' representatives of the predominant volcanic surface rocks of Mars, and offer researchers a glimpse of the magmatic history of that planet. Unfortunately, unraveling the parentage of a basaltic rock is not always straightforward. While many basalts are simple, unaltered partial melts of the mantle, others have undergone secondary processes which change the original parental chemistry, such as assimilation of other crustal rocks, mixing with other magmas, accumulation, re-equilibration between mineral species after crystallization, loss of late-stage magmatic fluids and alteration by metamorphic or metasomatic processes. Fortunately, magmatic inclusions can trap the evolving magmatic liquid, isolating it from many of these secondary processes and offering a direct look at the magma during different stages of development. These inclusions form when major or minor phases grow skeletally, surrounding small amounts of the parental magma within pockets in the growing crystal. The inclusion as a whole (usually consisting of glass with enclosed crystals) continues to represent the composition of the parental magma at the time the melt pocket closed, even when the rock as a whole evolves under changing conditions. The four basaltic martian meteorites contain several distinct generations of melt

  3. Seismic stratigraphic analysis of the Cenozoic sediments in the NW Faroe Shetland Basin – Implications for inherited structural control of sediment distribution

    DEFF Research Database (Denmark)

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


    and southwest. During Oligocene–Pliocene time the sediment influx was from north and northwest and the depocentre had moved in a westward direction closer to the Faroe Platform area. Emplacement of the Cenozoic sediments in the Faroese sector of the Faroe-Shetland Basin is controlled by thermal subsidence....... Understanding the older, structural elements and their control on sedimentation is a potential tool for understanding deviations from “normal” thermal subsidence and for predicting the prospectivity in the post-basalt succession in the Faroe-Shetland Basin....

  4. Hafnium isotope variations in oceanic basalts (United States)

    Patchett, P. J.; Tatsumoto, M.


    Hafnium isotope ratios generated by the beta(-) decay of Lu-176 are investigated in volcanic rocks derived from the suboceanic mantle. Hf-176/Hf-177 and Lu/Hf ratios were determined to precisions of 0.01-0.04% and 0.5%, respectively, by routine, low-blank chemistry. The Hf-176/Hf-177 ratio is found to be positively correlated with the Nd-143/Nd-144 ratio and negatively correlated with the Sr-87/Sr-86 and Pb-206/Pb-204 ratios, and to increase southwards along the Iceland-Reykjanes ridge traverse. An approximate bulk earth Hf-176/Hf-177 ratio of 0.28295 is inferred from the bulk earth Nd-143/Nd-144 ratio, which requires a bulk earth Lu/Hf ratio of 0.25, similar to the Juvinas eucrite. Midocean ridge basalts are shown to account for 60% of the range of Hf isotope ratios, and it is suggested that Lu-Hf fractionation is decoupled from Sm-Nd and Rb-Sr fractionation in very trace-element-depleted source regions as a result of partial melting.

  5. The relationship of seismic velocity structure and surface fracture characteristics of basalt outcrops to rippability estimates

    International Nuclear Information System (INIS)

    Kay, S.E.; Dougherty, M.E.; Pelton, J.R.


    Seismic velocity has been shown in previous engineering studies to be related to the fracture characteristics and rippability of rock outcrops. However, common methods of measuring seismic velocity in outcrops do not take into account the many possible travel paths for wave propagation and the fact that velocity zones may exist within an outcrop. Presented here are the results of using raytracing inversion of first-arrival travel-time data to map P-velocity structure in basalt outcrops, and also the investigation of the relationship of the mapped velocities to observed surface fractures and hand-sample P-velocities. It is shown that basalt outcrops commonly consist of an irregular near-surface low-velocity zone underlain by higher velocity material; that velocity gradients can exist in outcrops; that hand-sample velocity measurements are typically higher than outcrop-scale measurements; and that the characteristics of surface fractures are empirically related to near-surface P-velocity. All of these findings are relevant to the estimated rippability of rock in geotechnical engineering. The data for this study are derived from eleven sites on basalt outcrops of the Troodos Ophiolite in Cyprus. The basalt types include pillow basalts, massive flows, and a pillow breccia. A commonly available raytracing inversion program (RAYINVR) was used to produce a velocity profile of each outcrop. Different velocity zones were detailed by inverting observed travel times to produce a model of outcrop velocity structure which produces rippability profiles for each outcrop. 16 refs., 9 figs

  6. Assessment and Evaluation of Volcanic Rocks Used as Construction ...

    African Journals Online (AJOL)

    Addis Ababa capital city of Ethiopia at an elevation of about 2000 m above mean sea level is entirely covered with volcanic rocks, basalt, trachyte, ignimbrite and rhyolite. Construction industry makes use these rocks extensively and indiscriminately for structural loading, pavements, wall cladding, fencing, as cobblestone ...

  7. Nuclear waste repository in basalt: a design description

    International Nuclear Information System (INIS)

    Ritchie, J.S.; Schmidt, B.


    The conceptual design of a nuclear waste repository in basalt is described. Nuclear waste packages are placed in holes drilled into the floor of tunnels at a depth of 3700 ft. About 100 miles of tunnels are required to receive 35,000 packages. Five shafts bring waste packages, ventilation air, excavated rock, personnel, material, and services to and from the subsurface. The most important surface facility is the waste handling building, located over the waste handling shaft, where waste is received and packaged for storage. Two independent ventilation systems are provided to avoid potential contamination of spaces that do not contain nuclear waste. Because of the high temperatures at depth, an elaborate air chilling system is provided. Because the waste packages deliver a considerable amount of heat energy to the rock mass, particular attention is paid to heat transfer and thermal stress studies. 3 references, 31 figures, 3 tables

  8. A new basaltic glass microanalytical reference material for multiple techniques (United States)

    Wilson, Steve; Koenig, Alan; Lowers, Heather


    The U.S. Geological Survey (USGS) has been producing reference materials since the 1950s. Over 50 materials have been developed to cover bulk rock, sediment, and soils for the geological community. These materials are used globally in geochemistry, environmental, and analytical laboratories that perform bulk chemistry and/or microanalysis for instrument calibration and quality assurance testing. To answer the growing demand for higher spatial resolution and sensitivity, there is a need to create a new generation of microanalytical reference materials suitable for a variety of techniques, such as scanning electron microscopy/X-ray spectrometry (SEM/EDS), electron probe microanalysis (EPMA), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), and secondary ion mass spectrometry (SIMS). As such, the microanalytical reference material (MRM) needs to be stable under the beam, be homogeneous at scales of better than 10–25 micrometers for the major to ultra-trace element level, and contain all of the analytes (elements or isotopes) of interest. Previous development of basaltic glasses intended for LA-ICP-MS has resulted in a synthetic basaltic matrix series of glasses (USGS GS-series) and a natural basalt series of glasses (BCR-1G, BHVO-2G, and NKT-1G). These materials have been useful for the LA-ICP-MS community but were not originally intended for use by the electron or ion beam community. A material developed from start to finish with intended use in multiple microanalytical instruments would be useful for inter-laboratory and inter-instrument platform comparisons. This article summarizes the experiments undertaken to produce a basalt glass reference material suitable for distribution as a multiple-technique round robin material. The goal of the analytical work presented here is to demonstrate that the elemental homogeneity of the new glass is acceptable for its use as a reference material. Because the round robin exercise is still underway, only

  9. From shifting silt to solid stone: the manufacture of synthetic basalt in ancient mesopotamia (United States)

    Stone; Lindsley; Pigott; Harbottle; Ford


    Slabs and fragments of gray-black vesicular "rock," superficially resembling natural basalt but distinctive in chemistry and mineralogy, were excavated at the second-millennium B.C. Mesopotamian city of Mashkan-shapir, about 80 kilometers south of Baghdad, Iraq. Most of this material appears to have been deliberately manufactured by the melting and slow cooling of local alluvial silts. The high temperatures (about 1200 degreesC) required and the large volume of material processed indicate an industry in which lithic materials were manufactured ("synthetic basalt") for grinding grain and construction.

  10. Rock fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W.S.; Green, S.J.; Hakala, W.W.; Hustrulid, W.A.; Maurer, W.C. (eds.)


    Experts in rock mechanics, mining, excavation, drilling, tunneling and use of underground space met to discuss the relative merits of a wide variety of rock fragmentation schemes. Information is presented on novel rock fracturing techniques; tunneling using electron beams, thermocorer, electric spark drills, water jets, and diamond drills; and rock fracturing research needs for mining and underground construction. (LCL)

  11. Meso-Cenozoic evolution of the Tuareg Shield (Algeria, Sahara): insights from new thermochronological data (United States)

    Rougier, Sylvain; Missenard, Yves; Gautheron, Cécile; Barbarand, Jocelyn; Zeyen, Hermann; Pinna, Rosella; Liégeois, Jean-Paul; Bonin, Bernard; Ouabadi, Aziouz; El-Messaoud Derder, Mohammed; Frizon de Lamotte, Dominique; Kettouche, Djouher


    In North Africa, Meso-Cenozoic large scale topographic swells, such as Hoggar, Tibesti or Darfur domes, are superimposed to a Paleozoic arch and basin morphology which characterizes this region. Although these topographic highs are associated to Cenozoic intraplate volcanism, their development remains poorly constrained, both from temporal and spatial points of view. This study is focused on the Tuareg Shield bulge, a topographic high where Precambrian rocks, exposed over 500000 km², can reach 2400 m above sea level (Atakor district, Hoggar, South Algeria). While presumed Cretaceous sedimentary remnants, resting unconformably over the basement, suggest a possible stage of weak topography during the Mesozoic, current high topography is emphasized by performed. As previously deduced from apatite (U-Th)/He analyzes, these modelings show that samples underwent a heating to at least 80°C before their Late Eocene exhumation. Moreover, they also indicate that samples underwent another cooling stage during Lower Cretaceous, prior to Upper Cretaceous/Paleogene heating. We interpret these results as an evidence of a large-scale subsidence stage after the Cretaceous and until the Eocene, which allowed the deposition of a 1.5 to 3 km thick sedimentary cover and a heating at ~80°C of the currently outcropping basement. During the Eocene, the establishment of a thermal anomaly beneath the Tuareg Shield lithosphere resulted in erosion of the major part of this cover and, since 35 Ma, the development of intraplate volcanism.

  12. First Recovery of Submarine Basalts from the Chukchi Borderland and Alpha / Mendeleev Ridge, Arctic Ocean (United States)

    Andronikov, A.; Mukasa, S.; Mayer, L. A.; Brumley, K.


    In addition to multibeam bathymetric mapping of the Amerasia Basin in the high Arctic Ocean, the August- September 2008 cruise of USCGC Icebreaker HEALY (HLY0805) conducted a total of seven dredging profiles along the southern sectors of the Alpha/Mendeleev Ridge and in the northernmost region of Northwind Ridge of Chukchi Borderland. Five of the seven dredges were recovered on relatively gentle slopes (30-40°) and yielded mostly mud with a small number of fragments of sedimentary rocks and ice rafted debris (IRD), which indicates either rapid sedimentation rates on the bathymetrically high features sampled or lack of recently active volcanism on these features. Two dredges taken from steep escarpments with slopes (> 55°) at >3.5 km depth recovered some of the first known submarine basaltic samples from the Arctic Ocean floor away from the Gakkel Ridge. Ragged, freshly exposed edges indicate that these samples were broken from outcrop rather than being IRD. In some cases (e.g., a rise on the ocean floor between the Alpha/Mendeleev Ridge and Northwind Ridge) the samples have well-preserved pillow-basalt structures with fresh glassy rims up to 4 cm thick. Inward from the rims, the rocks are dark-grey lavas, some with visible plagioclase laths and rare phenocrysts up to 0.5 mm in length, some with visible signs of alteration such as local occurrence of chlorite. Surfaces that were exposed to water can be covered with a thin black film of Mn oxides. Occurrence of this volcanism away from any obvious spreading centers compels us to hypothesize that forthcoming geochemical analyses are likely to identify these rocks as the first Arctic Ocean floor samples to exhibit ocean island basalt compositions. The dredge taken from the northern slope of Northwind Ridge, along slopes as steep as > 45°, recovered a variety of rock types including sedimentary and basaltic rocks. Some of the basalts have columnar jointing (the size of the columns is only up to 5-6 cm across

  13. Mineral Detector for Igneous Rocks (United States)

    Ishikawa, S. T.; Hart, S. D.; Gulick, V. C.


    We present a Raman spectral analysis tool that uses machine learning algorithms to classify pure minerals in igneous rocks. Experiments show greater than 90% accuracy classifying a test set of pure minerals against a database of similar reference minerals using an artificial neural network. Efforts are currently underway to improve this tool for use as a mineral detector in rock samples, an important milestone toward autonomously classifying rocks based on spectral, and previous imaging work. Although pure mineral classification has been widely successful, applying the same methods to rocks is difficult because the spectra may represent a combination of multiple, and often competing, mineral signatures. In such cases some minerals may appear with more intensity than others resulting in masking of weaker minerals. Furthermore, with our particular spectrometer (852 nm excitation, ~50 micron spot size), minerals such as potassium feldspar fluoresce, both obscuring its characteristic Raman features and suppressing those of weaker minerals. For example, plagioclase and quartz, two key minerals for determining the composition of igneous rocks, are often hidden by minerals such as potassium feldspar and pyroxene, and are consequently underrepresented in the spectral analysis. These technicalities tend to skew the perceived composition of a rock from its actual composition. Despite these obstacles, an experiment involving a training set of 26 minerals (plagioclase, potassium feldspar, pyroxene, olivine, quartz) and a test set of 57 igneous rocks (basalt, gabbro, andesite, diorite, dacite, granodiorite, rhyolite, granite) shows that generalizations derived from their spectral data are consistent with expected trends: as rock composition goes from felsic to mafic there is a marked increase in the detection of minerals such as plagioclase and pyroxene along with a decrease in the detection of minerals such as quartz and potassium feldspar. The results suggest that phaneritic

  14. Fire effects on rock images and similar cultural resources [Chapter 5 (United States)

    Roger E. Kelly; Daniel F. McCarthy


    Throughout human global history, people have purposely altered natural rock surfaces by drilling, drawing, painting, incising, pecking, abrading and chiseling images into stone. Some rock types that present suitable media surfaces for these activities are fine-grained sandstones and granites, basalts, volcanic tuff, dolomites, and limestones. Commonly called rock...

  15. Cenozoic planktonic marine diatom diversity and correlation to climate change.

    Directory of Open Access Journals (Sweden)

    David Lazarus

    Full Text Available Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂(18O (climate and carbon cycle records (∂(13C, and 20-0 Ma pCO2. Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p.9, detrended r>.6, all p<.001, but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  16. Ground penetrating radar and seismic refraction investigation of fracture patterns in the basalt of Lucky Peak near Boise, Idaho

    International Nuclear Information System (INIS)

    Dougherty, M.E.; Hudson, W.K.; Kay, S.E.; Vincent, R.J.


    In hard rock environments, fluid flow and basement integrity are often controlled by the degree and connectivity of fracturing on an outcrop scale, rather than strictly by laboratory values of the permeability and competence of the matrix rock. Therefore, in many cases it is important to have a subsurface image of fracture characteristics of rock units in addition to an image of gross rock type. Fortunately, within a single rock type, many physical properties on outcrop scale are greatly influenced by fracturing, and changes in these physical properties should be detectable through the innovative use of geophysical methods. Work presented here is an attempt to use surface geophysical methods to delineate areas within a basalt flow which display different fracture characteristics and which have different electrical and seismic properties. The Basalt of Luck Peak is an intracanyon basalt flow exposed in cliffs around Lucky Peak Reservoir and in a terrace downstream from Lucky Peak Dam near Boise, Idaho. Visible in the face of the terrace below Lucky Peak Dam are the colonnade and entablature structures characteristic of differential cooling rates within basalt flows. Exposure of structural units within the cliff face is used to ground truth results from ground penetrating radar (GPR) and seismic refraction data collected along a line running perpendicular and away from the top edge of the cliff. 19 refs., 6 figs

  17. Gusev Rocks Solidified from Lava (3-D) (United States)


    In recent weeks, as NASA's Mars Exploration Rover Spirit has driven through the basin south of 'Husband Hill,' it has been traversing mainly sand and dune deposits. This week, though, Spirit has been maneuvering along the edge of an arc-shaped feature called 'Lorre Ridge' and has encountered some spectacular examples of basaltic rocks with striking textures. This panoramic camera (Pancam) image shows a group of boulders informally named 'FuYi.' These basaltic rocks were formed by volcanic processes and may be a primary constituent of Lorre Ridge and other interesting landforms in the basin. Spirit first encountered basalts at its landing site two years ago, on a vast plain covered with solidified lava that appeared to have flowed across Gusev Crater. Later, basaltic rocks became rare as Spirit climbed Husband Hill. The basaltic rocks that Spirit is now seeing are interesting because they exhibit many small holes or vesicles, similar to some kinds of volcanic rocks on Earth. Vesicular rocks form when gas bubbles are trapped in lava flows and the rock solidifies around the bubbles. When the gas escapes, it leaves holes in the rock. The quantity of gas bubbles in rocks on Husband Hill varies considerably; some rocks have none and some, such as several here at FuYi, are downright frothy. The change in textures and the location of the basalts may be signs that Spirit is driving along the edge of a lava flow. This lava may be the same as the basalt blanketing the plains of Spirit's landing site, or it may be different. The large size and frothy nature of the boulders around Lorre Ridge might indicate that eruptions once took place at the edge of the lava flow, where the lava interacted with the rocks of the basin floor. Scientists hope to learn more as Spirit continues to investigate these rocks. As Earth approaches the Chinese New Year (The Year of the Dog), the Athena science team decided to use nicknames representing Chinese culture and geography to identify rocks and

  18. Gusev Rocks Solidified from Lava (False Color) (United States)


    In recent weeks, as NASA's Mars Exploration Rover Spirit has driven through the basin south of 'Husband Hill,' it has been traversing mainly sand and dune deposits. This week, though, Spirit has been maneuvering along the edge of an arc-shaped feature called 'Lorre Ridge' and has encountered some spectacular examples of basaltic rocks with striking textures. This panoramic camera (Pancam) image shows a group of boulders informally named 'FuYi.' These basaltic rocks were formed by volcanic processes and may be a primary constituent of Lorre Ridge and other interesting landforms in the basin. Spirit first encountered basalts at its landing site two years ago, on a vast plain covered with solidified lava that appeared to have flowed across Gusev Crater. Later, basaltic rocks became rare as Spirit climbed Husband Hill. The basaltic rocks that Spirit is now seeing are interesting because they exhibit many small holes or vesicles, similar to some kinds of volcanic rocks on Earth. Vesicular rocks form when gas bubbles are trapped in lava flows and the rock solidifies around the bubbles. When the gas escapes, it leaves holes in the rock. The quantity of gas bubbles in rocks on Husband Hill varies considerably; some rocks have none and some, such as several here at FuYi, are downright frothy. The change in textures and the location of the basalts may be signs that Spirit is driving along the edge of a lava flow. This lava may be the same as the basalt blanketing the plains of Spirit's landing site, or it may be different. The large size and frothy nature of the boulders around Lorre Ridge might indicate that eruptions once took place at the edge of the lava flow, where the lava interacted with the rocks of the basin floor. Scientists hope to learn more as Spirit continues to investigate these rocks. As Earth approaches the Chinese New Year (The Year of the Dog), the Athena science team decided to use nicknames representing Chinese culture and geography to identify rocks and

  19. Norway and adjacent sedimentary basins during Cenozoic times - sediment fluxes, accumulation rates and mass balance

    DEFF Research Database (Denmark)

    Gołędowski, Bartosz; Nielsen, S.B.; Clausen, O.R.


    The objective of this study is to investigate varying sediment fluxes from the Scandinavian landmass during Cenozoic times and to calculate a mass balance from the observed accumulation rates. As the onshore area provides little data to quantify erosion rates and vertical movements of rock mass, we...... use offshore data from adjacent sedimentary basins (the North Sea and the Norwegian shelf) to calculate the amount of erosion. We have used a broad dataset of seismic 2D lines to map depositional units and a well dataset for the stratigraphic control and the velocity distribution in the sediments. We...... have therefore obtained accumulation rates in meters per million years for 5 depositional units in three areas - Southern North Sea, Central and Northern North Sea and the Norwegian shelf. Furthermore, taking into account the decay of porosity in sediments with burial depth, we have estimated...

  20. Selection of the host rock for high level radioactive waste repository in China

    International Nuclear Information System (INIS)

    Jin Yuanxin; Wang Wenguang; Chen Zhangru


    The authors has briefly introduced the experiences of the host rock selection and the host rock types in other countries for high level radioactive waste repository. The potential host rocks in China are investigated. They include granite, tuff, clay, basalt, salt, and loess. The report has expounded the distributions, scale, thickness, mineral and chemical composition, construction, petrogenesis and the ages of the rock. The possibility of these rocks as the host rock has been studied. The six pieces of distribution map of potential rocks have been made up. Through the synthetical study, it is considered that granite as the host rock of high level radioactive waste repository is possible

  1. Linking geology, fluid chemistry, and microbial activity of basalt- and ultramafic-hosted deep-sea hydrothermal vent environments. (United States)

    Perner, M; Hansen, M; Seifert, R; Strauss, H; Koschinsky, A; Petersen, S


    Hydrothermal fluids passing through basaltic rocks along mid-ocean ridges are known to be enriched in sulfide, while those circulating through ultramafic mantle rocks are typically elevated in hydrogen. Therefore, it has been estimated that the maximum energy in basalt-hosted systems is available through sulfide oxidation and in ultramafic-hosted systems through hydrogen oxidation. Furthermore, thermodynamic models suggest that the greatest biomass potential arises from sulfide oxidation in basalt-hosted and from hydrogen oxidation in ultramafic-hosted systems. We tested these predictions by measuring biological sulfide and hydrogen removal and subsequent autotrophic CO2 fixation in chemically distinct hydrothermal fluids from basalt-hosted and ultramafic-hosted vents. We found a large potential of microbial hydrogen oxidation in naturally hydrogen-rich (ultramafic-hosted) but also in naturally hydrogen-poor (basalt-hosted) hydrothermal fluids. Moreover, hydrogen oxidation-based primary production proved to be highly attractive under our incubation conditions regardless whether hydrothermal fluids from ultramafic-hosted or basalt-hosted sites were used. Site-specific hydrogen and sulfide availability alone did not appear to determine whether hydrogen or sulfide oxidation provides the energy for primary production by the free-living microbes in the tested hydrothermal fluids. This suggests that more complex features (e.g., a combination of oxygen, temperature, biological interactions) may play a role for determining which energy source is preferably used in chemically distinct hydrothermal vent biotopes. © 2013 John Wiley & Sons Ltd.

  2. Alkaline volcanic rocks from the Columbia Hills, Gusev crater, Mars (United States)

    McSween, H.Y.; Ruff, S.W.; Morris, R.V.; Bell, J.F.; Herkenhoff, K.; Gellert, Ralf; Stockstill, K.R.; Tornabene, L.L.; Squyres, S. W.; Crisp, J.A.; Christensen, P.R.; McCoy, T.J.; Mittlefehldt, D. W.; Schmidt, M.


    Irvine, Backstay, and Wishstone are the type specimens for three classes of fine-grained or fragmental, relatively unaltered rocks with distinctive thermal emission spectra, found as float on the flanks of the Columbia Hills. Chemical analyses indicate that these rocks are mildly alkaline basalt, trachybasalt, and tephrite, respectively. Their mineralogy consists of Na- and K-rich feldspar(s), low- and high-Ca pyroxenes, ferroan olivine, Fe-Ti (and possibly Cr) oxides, phosphate, and possibly glass. The texture of Wishstone is consistent with a pyroclastic origin, whereas Irvine and Backstay are lavas or possibly dike rocks. Chemical compositions of these rocks plot on or near liquid lines of descent for most elements calculated for Adirondack class rocks (olivine-rich basalts from the Gusev plains) at various pressures from 0.1 to 1.0 GPa. We infer that Wishstone-, Backstay-, and Irvine-class magmas may have formed by fractionation of primitive, oxidized basaltic magma similar to Adirondack-class rocks. The compositions of all these rocks reveal that the Gusev magmatic province is alkaline, distinct from the subalkaline volcanic rocks thought to dominate most of the planet's surface. The fact that differentiated volcanic rocks were not encountered on the plains prior to ascending Husband Hill may suggest a local magma source for volcanism beneath Gusev crater. Copyright 2006 by the American Geophysical Union.

  3. Long-term stability of global erosion rates and weathering during late-Cenozoic cooling. (United States)

    Willenbring, Jane K; von Blanckenburg, Friedhelm


    Over geologic timescales, CO(2) is emitted from the Earth's interior and is removed from the atmosphere by silicate rock weathering and organic carbon burial. This balance is thought to have stabilized greenhouse conditions within a range that ensured habitable conditions. Changes in this balance have been attributed to changes in topographic relief, where varying rates of continental rock weathering and erosion are superimposed on fluctuations in organic carbon burial. Geological strata provide an indirect yet imperfectly preserved record of this change through changing rates of sedimentation. Widespread observations of a recent (0-5-Myr) fourfold increase in global sedimentation rates require a global mechanism to explain them. Accelerated uplift and global cooling have been given as possible causes, but because of the links between rates of erosion and the correlated rate of weathering, an increase in the drawdown of CO(2) that is predicted to follow may be the cause of global climate change instead. However, globally, rates of uplift cannot increase everywhere in the way that apparent sedimentation rates do. Moreover, proxy records of past atmospheric CO(2) provide no evidence for this large reduction in recent CO(2) concentrations. Here we question whether this increase in global weathering and erosion actually occurred and whether the apparent increase in the sedimentation rate is due to observational biases in the sedimentary record. As evidence, we recast the ocean dissolved (10)Be/(9)Be isotope system as a weathering proxy spanning the past approximately 12 Myr (ref. 14). This proxy indicates stable weathering fluxes during the late-Cenozoic era. The sum of these observations shows neither clear evidence for increased erosion nor clear evidence for a pulse in weathered material to the ocean. We conclude that processes different from an increase in denudation caused Cenozoic global cooling, and that global cooling had no profound effect on spatially and

  4. Subseafloor basalts as fungal habitats

    Directory of Open Access Journals (Sweden)

    M. Ivarsson


    Full Text Available The oceanic crust is believed to host the largest potential habitat for microbial life on Earth, yet, still we lack substantial information about the abundance, diversity, and consequence of its biosphere. The last two decades have involved major research accomplishments within this field and a change in view of the ocean crust and its potential to harbour life. Here fossilised fungal colonies in subseafloor basalts are reported from three different seamounts in the Pacific Ocean. The fungal colonies consist of various characteristic structures interpreted as fungal hyphae, fruit bodies and spores. The fungal hyphae are well preserved with morphological characteristics such as hyphal walls, septa, thallic conidiogenesis, and hyphal tips with hyphal vesicles within. The fruit bodies consist of large (∼50–200 µm in diameter body-like structures with a defined outer membrane and an interior filled with calcite. The fruit bodies have at some stage been emptied of their contents of spores and filled by carbonate-forming fluids. A few fruit bodies not filled by calcite and with spores still within support this interpretation. Spore-like structures (ranging from a few µm to ∼20 µm in diameter are also observed outside of the fruit bodies and in some cases concentrated to openings in the membrane of the fruit bodies. The hyphae, fruit bodies and spores are all closely associated with a crust lining the vein walls that probably represent a mineralized biofilm. The results support a fungal presence in deep subseafloor basalts and indicate that such habitats were vital between ∼81 and 48 Ma.

  5. Late Cenozoic volcanism, subduction, and extension in the Lassen region of California, Southern Cascade Range

    Energy Technology Data Exchange (ETDEWEB)

    Guffanti, M. (Geological Survey, Reston, VA (USA)); Clynne, M.A.; Smith, J.G.; Muffler, L.J.P.; Bullen, T.D. (Geological Survey, Menlo Park, CA (USA))


    The authors identify 537 volcanic vents younger than 7 Ma, and they classify these into five age intervals and five compositional categories based on SiO{sub 2} content. Maps of vents by age and composition illustrate regionally representative volcanic trends. Most mafic volcanism is calcalkaline basalt and basaltic andesite. However, lesser volume of low-potassium olivine tholeiite (LKOT), a geochemically distinctive basalt type found in the northern Basin and Range province, also has erupted throughout the Lassen segment of the Cascade arc since the Pliocene. Normal faults and linear groups of vents are evidence of widespread crustal extension throughout most of the Lassen region. NNW alignments of these features indicate NNW orientation of maximum horizontal stress (ENE extension), which is similar to the stress regime in the adjacent northwestern Basin and Range and northern Sierra Nevada provinces. They interpret the western limit of the zone of NNW trending normal faults as the western boundary of the Basin and Range province where it overlaps the Lassen segment of the Cascade arc. The Lassen volcanic region occurs above the subducting Gorda North plate but also lies within a broad zone of distributed extension that occurs in the North American lithosphere east and southeast of the present Cascadia subduction zone. The scarcity of volcanic rocks older than 7 Ma suggests that a more compressive lithospheric stress regime prior to the late Miocene extensional episode may have suppressed volcanism, even though subduction probably was occurring beneath the Lassen region.

  6. Rock Pore Structure as Main Reason of Rock Deterioration (United States)

    Ondrášik, Martin; Kopecký, Miloslav


    Crashed or dimensional rocks have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material - concrete includes large amounts of crashed rock, especially limestone, dolostone and andesite. However, rock as any other material if exposed to exogenous processes starts to deteriorate. Especially mechanical weathering can be very intensive if rock with unsuitable rock properties is used. For long it had been believed that repeated freezing and thawing in relation to high absorption is the main reason of the rock deterioration. In Slovakia for many years the high water absorption was set as exclusion criterion for use of rocks and stones in building industry. Only after 1989 the absorption was accepted as merely informational rock property and not exclusion. The reason of the change was not the understanding of the relationship between the porosity and rock deterioration, but more or less good experiences with some high porous rocks used in constructions exposed to severe weather conditions and proving a lack of relationship between rock freeze-thaw resistivity and water absorption. Results of the recent worldwide research suggest that understanding a resistivity of rocks against deterioration is hidden not in the absorption but in the structure of rock pores in relation to thermodynamic properties of pore water and tensile strength of rocks and rock minerals. Also this article presents some results of research on rock deterioration and pore structure performed on 88 rock samples. The results divide the rocks tested into two groups - group N in which the pore water does not freeze

  7. Age and provenance of Triassic to Cenozoic sediments of West and Central Sarawak, Malaysia (United States)

    Breitfeld, H. Tim; Galin, Thomson; Hall, Robert


    Sarawak is located on the northern edge of Sundaland in NW Borneo. West and Central Sarawak include parts of the Kuching and Sibu Zones. These contain remnants of several sedimentary basins with ages from Triassic to Cenozoic. New light mineral, heavy mineral and U-Pb detrital zircon ages show differences in provenance reflecting the tectonic evolution of the region. The oldest clastic sediments are Triassic (Sadong Formation and its deep marine equivalent Kuching Formation). They were sourced by a Triassic (Carnian to Norian) volcanic arc and reworked Paleoproterozoic detritus derived from Cathaysialand. The Upper Jurassic to Cretaceous Pedawan Formation is interpreted as forearc basin fill with distinctive zircon populations indicating subduction beneath present-day West Sarawak which initiated in the Late Jurassic. Subsequent subduction until the early Late Cretaceous formed the Schwaner Mountains magmatic arc. After collision of SW Borneo and other microcontinental fragments with Sundaland in the early Late Cretaceous, deep marine sedimentation (Pedawan Formation) ceased, and there was uplift forming the regional Pedawan-Kayan unconformity. Two episodes of extension followed and were responsible for basin development on land in West Sarawak from the latest Cretaceous onwards, probably in a pull-apart setting. The first episode is associated with sediments of the Kayan Group, deposited in the Latest Cretaceous (Maastrichtian) to Eocene, and the second episode with Upper Eocene sediments of the Ketungau Basin. Zircon ages indicate volcanic activity throughout the Early Cenozoic in NW Borneo, and inherited zircon ages indicate reworking of Triassic and Cretaceous rocks. A large deep marine basin, the Rajang Basin, was north of the Lupar Line Fault in Central Sarawak (Sibu Zone) from the Late Cretaceous to the Late Eocene. Zircons from sediments of the Rajang Basin indicate they have similar ages and provenance to contemporaneous terrestrial sediments of the Kayan

  8. Basalt fibers: the green material of the XXI-century, for a sustainable restoration of historical buildings

    Directory of Open Access Journals (Sweden)

    Giacomo Di Ruocco


    Full Text Available In recent decades in the construction industry, the need to experience consolidation techniques with non-corroding materials is being developed. Studies and tests have been led about integration of basalt fibers in concrete structures: they have shown improvements both in terms of mechanical strength and in terms of intervention of consolidation durability (Ólafsson, Thorhallsson, 2009. The basalt rock can be used to produce not only basalt bars, but also fabrics, paddings, continuous filaments and basalt network. Some applications of these basalt-composites materials concern the consolidation of civil construction structures, thermal and acoustic insulation, security clothing, etc. Some years ago the Italian company ENEA (National Agency for New Technologies, Energy and Sustainable Economic Development has signed an agreement with HG GBF (one of the world's leading companies in the production of basalt fibers, for the verification of possible applications of this material in the construction field but also in the nautical and automotive ones. The use of basalt fiber in construction could present a series of advantages: natural origin, a cycle of production to lower energy impact compared to other fibers, a high chemical inertia and thus a high degree of durability, low thermal conductivity, good mechanical and thermo-acoustic properties, high fire resistance, a competitive cost and, in general, more environmental compatibility and sustainability than other synthetic fibers.

  9. Paleoproterozoic arc basalt-boninite-high magnesian andesite-Nb enriched basalt association from the Malangtoli volcanic suite, Singhbhum Craton, eastern India: Geochemical record for subduction initiation to arc maturation continuum (United States)

    Rajanikanta Singh, M.; Manikyamba, C.; Ganguly, Sohini; Ray, Jyotisankar; Santosh, M.; Dhanakumar Singh, Th.; Chandan Kumar, B.


    The Singhbhum Craton of eastern India preserves distinct signatures of ultramafic-mafic-intermediate-felsic magmatism of diverse geodynamic affiliations spanning from Paleo-Mesoarchean to Proterozoic. Here we investigate the 2.25 Ga Malangtoli volcanic rocks that are predominantly clinopyroxene- and plagioclase-phyric, calc-alkaline in nature, display basalt-basaltic andesite compositions, and preserve geochemical signatures of subduction zone magmatism. Major, trace and rare earth element characteristics classify the Malangtoli volcanic rocks as arc basalts, boninites, high magnesian andesites (HMA) and Nb enriched basalts (NEB). The typical LILE enriched-HFSE depleted geochemical attributes of the arc basalts corroborate a subduction-related origin. The boninitic rocks have high Mg# (0.8), MgO (>25 wt.%), Ni and Cr contents, high Al2O3/TiO2 (>20), Zr/Hf and (La/Sm)N (>1) ratios with low (Gd/Yb)N (54 wt.%), MgO (>6 wt.%), Mg# (0.47) with elevated Cr, Co, Ni and Th contents, depleted (Nb/Th)N, (Nb/La)N, high (Th/La)N and La/Yb (Y with low Sr/Y. The NEBs have higher Nb contents (6.3-24 ppm), lower magnitude of negative Nb anomalies with high (Nb/Th)pm = 0.28-0.59 and (Nb/La)pm = 0.40-0.69 and Nb/U = 2.8-34.4 compared to normal arc basalts [Nb = generation of NEB. Thus, the arc basalt-boninite-HMA-NEB association from Malangtoli volcanic suite in Singhbhum Craton preserves the signature of a complete spectrum of Paleoproterozoic active convergent margin processes spanning from subduction initiation to arc maturation.

  10. A synthesis of Cenozoic sedimentation in the North Sea

    DEFF Research Database (Denmark)

    Anell, Ingrid Anna Margareta; Thybo, Hans; Rasmussen, E.S.


    The North Sea Basin contains an almost complete record of Cenozoic sedimentation, separated by clear regional unconformities. The changes in sediment characteristics, rate and source, and expression of the unconformities reflect the tectonic, eustatic and climatic changes that the North Sea and its...... margins have undergone. While the North Sea has been mapped locally, we present the first regional mapping of the Cenozoic sedimentary strata. Our study provides a new regional sub-division of the main seismic units in the North Sea together with maps of depocentres, influx direction and source areas. Our...... characteristics of many unconformities indicate that they were generated by eustatic sea-level fall, often in conjunction with other processes. Early Cenozoic unconformities, however, relate to tectonism associated with the opening of the North Atlantic. From observation on a regional scale, we infer...

  11. Permeameter studies of water flow through cement and clay borehole seals in granite, basalt and tuff

    Energy Technology Data Exchange (ETDEWEB)

    South, D.L.; Daemen, J.J.K.


    Boreholes near a repository must be sealed to prevent rapid migration of radionuclide-contaminated water to the accessible environment. The objective of this research is to assess the performance of borehole seals under laboratory conditions, particularly with regard to varying stress fields. Flow through a sealed borehole is compared with flow through intact rock. Cement or bentonite seals have been tested in granite, basalt, and welded tuff. The main conclusion is that under laboratory conditions, existing commercial materials can form high quality seals. Triaxial stress changes about a borehole do not significantly affect seal performance if the rock is stiffer than the seal. Temperature but especially moisture variations (drying) significantly degrade the quality of cement seals. Performance partially recovers upon resaturation. A skillfully sealed borehole may be as impermeable as the host rock. Analysis of the influence of relative seal-rock permeabilities shows that a plug with permeability one order of magnitude greater than that of the rock results in a flow increase through the hole and surrounding rock of only 1-1/2 times compared to the undisturbed rock. Since a borehole is only a small part of the total rock mass, the total effect is even less pronounced. The simplest and most effective way to decrease flow through a rock-seal system is to increase the seal length, assuming it can be guaranteed that no dominant by-pass flowpath through the rock exists.

  12. Science Rocks! (United States)

    Prestwich, Dorothy; Sumrall, Joseph; Chessin, Debby A.


    It all began one Monday morning. Raymond could not wait to come to large group. In his hand, he held a chunk of white granite he had found. "Look at my beautiful rock!" he cried. The rock was passed around and examined by each student. "I wonder how rocks are made?" wondered one student. "Where do they come from?"…

  13. Chopped basalt fibres: A new perspective in reinforcing poly(lactic acid to produce injection moulded engineering composites from renewable and natural resources

    Directory of Open Access Journals (Sweden)

    P. Tamas


    Full Text Available This paper focuses on the reinforcing of Poly(lactic acid with chopped basalt fibres by using silane treated and untreated basalt fibres. Composite materials with 5–10–15–20–30–40 wt% basalt fibre contents were prepared from silane sized basalt fibres using extrusion, and injection moulding, while composites with 5–10–15 wt% basalt fibre contents were also prepared by using untreated basalt fibres as control. The properties of the injection moulded composites were extensively examined by using quasi-static (tensile, three-point bending and dynamic mechanical tests (notched and unnotched Charpy impact tests, dynamic mechanical analysis (DMA, differential scanning calorimetry (DSC, heat deflection temperature (HDT analysis, dimensional stability test, as well as melt flow index (MFI analysis and scanning electron microscopic (SEM observations. It was found that silane treated chopped basalt fibres are much more effective in reinforcing Poly(lactic acid than natural fibres; although basalt fibres are not biodegradable but they are still considered as natural (can be found in nature in the form of volcanic rocks and biologically inert. It is demonstrated in this paper that by using basalt fibre reinforcement, a renewable and natural resource based composite can be produced by injection moulding with excellent mechanical properties suitable even for engineering applications. Finally it was shown that by using adequate drying of the materials, composites with higher mechanical properties can be achieved compared to literature data.

  14. Apollo 12 feldspathic basalts 12031, 12038, and 12072; petrology, comparison and interpretations

    International Nuclear Information System (INIS)

    Beaty, E.W.; Hill, S.M.R.; Albee, A.L.; Baldridge, W.S.


    Modal and chemical data indicate that 12072, 12038, and 12031, the Apollo 12 feldspathic basalts, form a well-defined group which cannot be related to the other Apollo 12 rock types. 12072 contains phenocrysts of olivine and pigeonite and microphenocrysts of Cr-spinel set in a fine-grained, variolitic groundmass. 12038 is a medium-grained, equigranular basalt with a texture indicating it was multiply saturated. 12031 is a coarse-grained rock with granular to graphic intergrowths of pyroxene and plagioclase; it was also multiply saturated. Petrologic observations, as well as the bulk chemistry, are consistent with the interpretation that 12031 could be derived from 12072 through fractionation of Cr-spinel, olivine, and pigeonite, the observed phenocryst assemblage. 12038, however, contains more pigeonite, less olivine, three times as much Ca-phosphate minerals, one-fifth as much troilite, and much more sodic plagioclase than 12072. These differences indicate that 12038 must have come from a separate igneous body. Consideration of the bulk compositions indicates that neither 12072 and 12031 nor 12038 could have been derived from the Apollo 12 olivine, pigeonite, or ilmenite basalts by crystal--liquid fractionation. The general petrologic similarities between 12072, 12031, and the other Apollo 12 basalts suggests that they were produced in either the same or similar source regions. 12038, however, is petrologically and chemically unique, and is probably exotic to the Apollo 12 landing site

  15. Green glass vitrophyre 78526 - An impact of very low-Ti mare basalt composition (United States)

    Warner, R. D.; Taylor, G. J.; Kiel, K.; Planner, H. H.; Nehru, C. E.; Ma, M.-S.; Schmitt, R. A.


    Rake sample 78526 is an 8.77 g rock consisting primarily of vitrophyric pale green glass with subordinate mineral and lithic relics. Petrographic and compositional evidence leads to the following conclusions: (1) the bulk composition represents that of a mixture formed by impact melting of at least two different textural and compositional varieties of VLT mare basalt that are now present in the rock as lithic relics and a poorly defined low-Ti mare basalt component observed in thin section only in the form of isolated mineral relics; (2) the admixed VLT mare basalts had REE abundances lower than those found in other mare basalts (but probably higher than emerald green glass) and REE patterns showing significant enrichment of the heavy relative to light REE's, suggesting that they were derived by comparatively high degrees of partial melting of a clinopyroxene-rich source region; and (3) the impact melt supercooled to produce the vitrophyre, with rather sharply contrasting textural domains present in the vitrophyre resulting from differences in nucleation kinetics and degrees of supercooling in various portions of the sample.

  16. Chronology and isotopic geochemistry of Apollo 14 basalts and Skaergard Gabbro, Eastern Greenland

    International Nuclear Information System (INIS)

    Dasch, E.J.


    Work completed on Apollo 14 basalts has been published. The two dates obtained from these rocks comprised the oldest and two of the three oldest ages (4.1 and 4.3 billion years) known for lunar maria basalts; thus their ages are important in understanding the moon's earliest history. Owing to the antiquity of these rocks, two more fragments have been dated as part of a second ASEE/NASA SFF program. The new ages are 3.95 and 4.12 billion years, thus further establishing and amplifying the earlier results. This work, although perhaps more interesting for its chronologic information, was begun as a test of chemical and petrographic models. Fragments of Apollo basalt were placed into five categories, based on petrologic and chemical, especially rare-earth element, composition. Isotopic studies were begun in an attempt to determine if the five groups of basalts were related by age or initial isotopic composition (isotopic composition of lava at time of extrusion). Although a few of the representatives of the five groups have the same age and/or initial strontium-isotopic composition, within the analtytical uncertainties, most apparently are unrelated. Petrologic implications of these data will be published in an appropriate journal

  17. Mineralogy of Apollo 15415 ?genesis rock' - Source of anorthosite on moon. (United States)

    Steele, I. M.; Smith, J. V.


    Results of electron microprobe analyses of plagioclase points and pyroxene grains of Apollo 15415 ?genesis rock.' It is pointed out that no evidence of cumulate textures has yet appeared to support suggestions of extensive crystal-liquid differentiation producing an anorthositic crust or a lunar crust composed of a mixture of plagioclase-rich rock, basalts and minor ultramafic material, which require that plagioclase crystals float in a basaltic liquid. The plagioclase in 15415 does not show cumulate texture either. It is noted that it remains to be seen whether rock 15415 is correctly named the ?genesis rock.'

  18. First thermochronological constraints on the Cenozoic extension along the Balkan fold-thrust belt (Central Stara Planina Mountains, Bulgaria) (United States)

    Kounov, Alexandre; Gerdjikov, Ianko; Vangelov, Dian; Balkanska, Eleonora; Lazarova, Anna; Georgiev, Stoyan; Blunt, Edward; Stockli, Daniel


    The Balkan fold-thrust belt, exposed in Bulgaria and north-east Serbia, is part of the north-east vergent segment of the bi-vergent Eastern Mediterranean Alpine orogen. It was formed during two distinct compressional stages; the first one lasted from the Middle Jurassic to the Early Cretaceous and the second from Late Cretaceous to the Paleogene. Although the compressional tectonic evolution of the Balkan fold-thrust belt since the Middle Jurassic and during most of the Mesozoic is relatively well studied, the final exhumation of the rocks of the belt during the Cenozoic has remained poorly understood. Here, we present the first thermochronological constraints, based on fission-track and [U-Th-(Sm)]/He analysis, showing that along the central part of the belt syn- to post-orogenic extension could have started as early as the middle Eocene. Low-temperature thermochronological analysis of samples collected from three areas reveals at least two phases of increased cooling and exhumation during the Cenozoic. The first exhumation phase took place between 44 and 30 Ma and appears to be related to the syn- to post-orogenic collapse coeval with the earliest Cenozoic extensional stage observed across the southern Balkan Peninsula. A period of relative quiescence (between 30 and 25 Ma) is followed by the next cooling stage, between 25 and 20 Ma, which appears to be related to late Oligocene to early Miocene crustal extension across the Balkan Peninsula. Extension accommodated by the late Miocene to Recent age Sub-Balkan Graben System does not appear to have produced exhumation of rocks from beneath 2-4 km depth, as it was not detected by the low-temperature thermochronological methods applied in this study.

  19. Nuclear waste repository in basalt: preconceptual design guidelines

    Energy Technology Data Exchange (ETDEWEB)


    The development of the basalt waste isolation program parallels the growing need for permanent, environmentally safe, and secure means to store nuclear wastes. The repository will be located within the Columbia Plateau basalt formations where these ends can be met and radiological waste can be stored. These wastes will be stored such that the wastes may be retrieved from storage for a period after placement. After the retrieval period, the storage locations will be prepared for terminal storage. The terminal storage requirements will include decommissioning provisions. The facility boundaries will encompass no more than several square miles of land which will be above a subsurface area where the geologic makeup is primarily deep basaltic rock. The repository will receive, from an encapsulation site(s), nuclear waste in the form of canisters (not more than 18.5 feet x 16 inches in diameter) and containers (55-gallon drums). Canisters will contain spent fuel (after an interim 5-year storage period), solidified high-level wastes (HLW), or intermediate-level wastes (ILW). The containers (drums) will package the low-level transuranic wastes (LL-TRU). The storage capacity of the repository will be expanded in a time-phased program which will require that subsurface development (repository expansion) be conducted concurrently with waste storage operations. The repository will be designed to store the nuclear waste generated within the predictable future and to allow for reasonable expansion. The development and assurance of safe waste isolation is of paramount importance. All activities will be dedicated to the protection of public health and the environment. The repository will be licensed by the US Nuclear Regulatory Commission (NRC). Extensive efforts will be made to assure selection of a suitable site which will provide adequate isolation.

  20. Nuclear waste repository in basalt: preconceptual design guidelines

    International Nuclear Information System (INIS)


    The development of the basalt waste isolation program parallels the growing need for permanent, environmentally safe, and secure means to store nuclear wastes. The repository will be located within the Columbia Plateau basalt formations where these ends can be met and radiological waste can be stored. These wastes will be stored such that the wastes may be retrieved from storage for a period after placement. After the retrieval period, the storage locations will be prepared for terminal storage. The terminal storage requirements will include decommissioning provisions. The facility boundaries will encompass no more than several square miles of land which will be above a subsurface area where the geologic makeup is primarily deep basaltic rock. The repository will receive, from an encapsulation site(s), nuclear waste in the form of canisters (not more than 18.5 feet x 16 inches in diameter) and containers (55-gallon drums). Canisters will contain spent fuel (after an interim 5-year storage period), solidified high-level wastes (HLW), or intermediate-level wastes (ILW). The containers (drums) will package the low-level transuranic wastes (LL-TRU). The storage capacity of the repository will be expanded in a time-phased program which will require that subsurface development (repository expansion) be conducted concurrently with waste storage operations. The repository will be designed to store the nuclear waste generated within the predictable future and to allow for reasonable expansion. The development and assurance of safe waste isolation is of paramount importance. All activities will be dedicated to the protection of public health and the environment. The repository will be licensed by the US Nuclear Regulatory Commission (NRC). Extensive efforts will be made to assure selection of a suitable site which will provide adequate isolation

  1. Mantle source heterogeneity of the Early Jurassic basalt of eastern North America (United States)

    Gregory Shellnutt, J.; Dostal, Jaroslav; Yeh, Meng-Wan


    One of the defining characteristics of the basaltic rocks from the Early Jurassic Eastern North America (ENA) sub-province of the Central Atlantic Magmatic Province (CAMP) is the systematic compositional variation from South to North. Moreover, the tectono-thermal regime of the CAMP is debated as it demonstrates geological and structural characteristics (size, radial dyke pattern) that are commonly associated with mantle plume-derived mafic continental large igneous provinces but is considered to be unrelated to a plume. Mantle potential temperature ( T P) estimates of the northern-most CAMP flood basalts (North Mountain basalt, Fundy Basin) indicate that they were likely produced under a thermal regime ( T P ≈ 1450 °C) that is closer to ambient mantle ( T P ≈ 1400 °C) conditions and are indistinguishable from other regions of the ENA sub-province ( T Psouth = 1320-1490 °C, T Pnorth = 1390-1480 °C). The regional mantle potential temperatures are consistent along the 3000-km-long ENA sub-province suggesting that the CAMP was unlikely to be generated by a mantle plume. Furthermore, the mantle potential temperature calculation using the rocks from the Northern Appalachians favors an Fe-rich mantle (FeOt = 8.6 wt %) source, whereas the rocks from the South Appalachians favor a less Fe-rich (FeOt = 8.3 wt %) source. The results indicate that the spatial-compositional variation of the ENA basaltic rocks is likely related to differing amounts of melting of mantle sources that reflect the uniqueness of their regional accreted terranes (Carolinia and West Avalonia) and their post-accretion, pre-rift structural histories.

  2. Meso-/Cenozoic long-term landscape evolution at the southern Moroccan passive continental margin, Tarfaya Basin, recorded by low-temperature thermochronology (United States)

    Sehrt, Manuel; Glasmacher, Ulrich A.; Stockli, Daniel F.; Jabour, Haddou; Kluth, Oliver


    This paper presents the first regional study of low-temperature thermochronology to be undertaken in the Tarfaya Basin at the southern Moroccan passive continental margin. The basin is characterised by vast subsidence since Mid-Triassic times, whereby up to 12 km of Meso- to Cenozoic sedimentary rocks accumulated. The study focused on the post-rift vertical movements along a typical ;passive; margin and besides dealt with the timing and maximum temperature reached by potential source rocks of the basin. To unravel the t-T development, thermochronological analyses were performed on 50 outcrop and well samples from Meso-Cenozoic rocks. Thermochronological data reveal a continuous subsidence phase in the offshore basin from Mid-Triassic to recent times. In contrast, apatite (U-Th-Sm)/He and apatite fission-track data as well as thermal modelling point to an inversion of the northeastern onshore basin starting in the Palaeogene at 65-55 Ma. The rock uplift and exhumation period resulted in the erosion of a 1.0-1.4 km thick Cretaceous-Palaeogene sedimentary pile contemporaneously with peak Atlas surface uplift in the Cenozoic. The exhumation stage could be an explanation for the increasing periodic influx of detrital material into the offshore and southern onshore Tarfaya Basin since Palaeocene. Detrital apatite fission-track ages from 92 (± 16) to 237 (± 35) Ma of the Upper Cretaceous-Neogene succession indicate no heating above 60 °C confirming immature to early mature Cenomanian to Campanian and Eocene source rocks in the onshore Tarfaya Basin.

  3. Hydrated Spinel Websterite Xenoliths From Moses Rock Diatreme, Navajo Volcanic Field: Metasomatism in the Mantle Wedge of the Colorado Plateau Above the De-watering Farallon Plate (United States)

    Schulze, D. J.; Chow, R.; Helmstaedt, H. H.


    Expansion and density decrease in ultramafic rocks in the mantle wedge above the subducted and dewatering Farallon Plate in the Cenozoic may have been the driving force behind uplift of the Colorado Plateau. Here we document the effects of such hydration on spinel websterites that resulted in rocks dominated by pargasitic amphibole, Mg-chlorite and Cr-magnetite/chromite. Xenoliths of spinel websterite from the Moses Rock diatreme in the Navajo Volcanic Field on the Colorado Plateau have granoblastic to mosaic porphyroclastic texture. Porphyroclasts (up to 2 cm across) of lamellar intergrowths of clinopyroxene and orthopyroxene are set in a granular matrix of sub-equal amounts of the two pyroxenes. Both pyroxenes are magnesian and aluminous, with Mg/(Mg+Fe) in the range 0.89 to 0.93 and Al2O3 contents of approximately 4.0 to 9.5 wt%. Many samples contain aluminous spinel with Al/(Al+Cr) = 0.82 to 0.94. The effects of hydration on these samples exist as partial to complete replacement of the pyroxenes by amphibole (tremolite/edenite/pargasite/magnesio-hornblende), pseudomorphing original pyroxene textures, and replacement of primary spinel by Cr-rich magnetite or chromite with Al/(Al+Cr) = 0.07 to 0.35 intergrown with, and surrounded by, clinochlore. Unusual minerals associated with replacement of primary spinel include one example with corundum + zoisite, one with secondary garnet (molar Ca:Mg:Fe = 20:40:40) and two samples with aluminous talc (5 to 7 wt% Al2O3). By analogy with Alpine peridotites and mantle xenolith suites from basalt occurrences, the spinel websterites probably existed as veins and lenses in spinel peridotite of the shallow upper mantle beneath the Colorado Plateau prior to hydration. De-watering of the subducted Farallon Plate in Cenozoic time was likely the source of water-rich fluids that caused the hydration at fairly shallow depths (within amphibole stability), as suggested for hydration of spinel peridotite xenoliths from the Buell Park and

  4. Strontium isotopes as tracers to delineate aquifer interactions and the influence of rainfall in the basalt plains of southeastern Australia (United States)

    Raiber, Matthias; Webb, John A.; Bennetts, Darren A.


    SummaryTo better understand the spatial distribution of groundwater salinisation in western Victoria, southeast Australia, the interactions between a surficial basalt aquifer and an underlying extensive palaeodrainage ('deep lead') system were studied using a multi-disciplinary approach, combining strontium isotope analyses with major ion chemistry and the interpretation of geological and hydrogeological data. The strontium isotopes proved particularly useful in delineating flow paths and hydraulic connections between the two aquifers, which have contrasting 87Sr/ 86Sr ratios. The freshest basalt groundwaters lie beneath volcanoes and have 87Sr/ 86Sr signatures close to the whole-rock strontium isotope ratios of the basalts (˜0.7045), indicating the strong influence of basalt weathering. With increasing distance from the eruption points, basalt groundwaters become progressively more saline and the strontium isotope ratios evolve towards the more radiogenic signatures of local rainfall (0.710-0.711), due to the slow addition of infiltration concentrated by evapotranspiration during its passage through the thick, clay-rich soils developed on the basalt lavas. Overall, the influence of rainwater on the strontium isotope signatures of the basalt groundwater is much greater than that of basaltic weathering, indicating that rainwater can play a greater role in determining groundwater strontium composition than is often realised. Most parts of the palaeodrainage system beneath the basalt are preferentially recharged through the volcanoes, as shown by strong downwards hydraulic gradients and groundwater 87Sr/ 86Sr ratios similar to the least radiogenic basalt groundwaters. However, in the northwestern part, groundwater 87Sr/ 86Sr ratios are closer to those of the source material of the sediments (Palaeozoic bedrock), indicating that here recharge occurs predominantly in the headwaters where the basalts are absent. In the southern and western sections of the palaeodrainage

  5. Underground engineering at the Basalt Waste Isolation Project

    International Nuclear Information System (INIS)


    A special task group was organized by the US National Committee for Rock Mechanics and the Board on Radioactive Waste Management of the National Research Council to address issues relating to the geotechnical site characterization program for an underground facility to house high-level radioactive waste of the Basalt Waste Isolation Project (BWIP). Intended to provide an overview of the geotechnical program, the study was carried out by a task group consisting of ten members with expertise in the many disciplines required to successfully complete such a project. The task group recognized from the outset that the short time frame of this study would limit its ability to address all geotechnical issues in detail. Geotechnical issues were considered to range from specific technical aspects such as in-situ testing for rock mass permeability; rock hardness testing in the laboratory; or geologic characterizations and quantification of joints, to broader aspects of design philosophy, data collection, and treatment of uncertainty. The task group chose to focus on the broader aspects of underground design and construction, recognizing that the BWIP program utilizes a peer review group on a regular basis which reviews the specific technical questions related to geotechnical engineering. In this way, it was hoped that the review provided by the task group would complement those prepared by the BWIP peer review group

  6. The Ethiopian subcontinental mantle domains: geochemical evidence from Cenozoic mafic lavas (United States)

    Tommasini, S.; Manetti, P.; Innocenti, F.; Abebe, T.; Sintoni, M.; Conticelli, S.


    Since the Cenozoic, Ethiopia was affected by a widespread volcanic activity related to the geodynamic evolution of the Afar triple junction. The plateau building phase was followed by the formation of the Main Ethiopian Rift (MER) accompanied by a bimodal volcanic activity in both the inner parts of the rift and its shoulders. Outside the rift, a concurrent volcanic activity occurred mainly along transversal tectonic lineaments, the most important of which is the Yerer-Tullu Wellel Volcano-Tectonic Lineament (YTVL) developing for ˜500 km westward of Addis Abeba. Scattered Pliocene Quaternary volcanoes are reported also inside the plateau such as those out cropping nearby Lake Tana. Here we present the result of a study on carefully screened mafic lavas outcropping in two sectors located off-axis the MER, namely, the YTVL and the southern part of Lake Tana; and in one sector located in the southern tip of the MER close to Megado, in the Sidamo region. The screened samples are petrographically fresh and have SiO24 wt.%, to minimise crystal fractionation effects. Most of the samples belong to the Late Miocene Quaternary volcanic activity of the East African Rift System (EARS), although a number of samples along the YTVL are representative of the Late Eocene Early Miocene Ethiopian Volcanic Plateau flood basalts. The selected mafic lavas offer the opportunity to assess the geochemical diversity, if any, of the subcontinental mantle domains along the MER (Megado and the easternmost part of the YTVL) and in sectors far away from the MER (YTVL and Lake Tana). The samples have a wide compositional range: from basanite to alkali basalt, hy-normative basalt, qz-normative basalt, basaltic andesite, hawaiite, trachybasalt, and trachyandesite. The major and trace element characteristics of the mafic lavas demonstrate an origin from a relatively fertile and trace element enriched lithospheric mantle at pressure variable from ˜2.0 to 3.5 GPa. Moreover, systematic variations in

  7. Giant Plagioclase Basalts, eruption rate versus time

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 111; Issue 4. Giant Plagioclase Basalts, eruption rate versus time: Response to Sheth's comments and some additional thoughts. Gautam Sen. Volume 111 Issue 4 December 2002 pp 487-488 ...

  8. Basalt waste added to Portland cement

    Directory of Open Access Journals (Sweden)

    Thiago Melanda Mendes


    Full Text Available Portland cement is widely used as a building material and more than 4.3 billion tons were produced in 2014, with increasing environmental impacts by this industry, mainly through CO2 emissions and consumption of non-removable raw materials. Several by-products have been used as raw materials or fuels to reduce environmental impacts. Basaltic waste collected by filters was employed as a mineral mixture to Portland cement and two fractions were tested. The compression strength of mortars was measured after 7 days and Scanning Electron Microscopy (SEM and Electron Diffraction Scattering (EDS were carried out on Portland cement paste with the basaltic residue. Gains in compression strength were observed for mixtures containing 2.5 wt.% of basaltic residue. Hydration products observed on surface of basaltic particles show the nucleation effect of mineral mixtures. Clinker substitution by mineral mixtures reduces CO2 emission per ton of Portland cement.

  9. Microbially mediated alteration of crystalline basalts as identified from analogical reactive percolation experiments (United States)

    Moore, Rachael; Ménez, Bénédicte; Stéphant, Sylvian; Dupraz, Sébastien; Ranchou-Peyruse, Magali; Ranchou-Peyruse, Anthony; Gérard, Emmanuelle


    Alteration in the ocean crust through fluid circulation is an ongoing process affecting the first kilometers and at low temperatures some alteration may be microbially mediated. Hydrothermal activity through the hard rock basement supports diverse microbial communities within the rock by providing nutrient and energy sources. Currently, the impact of basement hosted microbial communities on alteration is poorly understood. In order to identify and quantify the nature of microbially mediated alteration two reactive percolation experiments mimicking circulation of CO2 enriched ground water were performed at 35 °C and 30 bar for 21 days each. The experiments were performed using a crystalline basalt substrate from an earlier drilled deep Icelandic aquifer. One experiment was conducted on sterile rock while the other was conducted with the addition of a microbial inoculate derived from groundwater enrichment cultures obtained from the same aquifer. µCT on the experimental basaltic substrate before and after the reactive percolation experiment along with synchrotron radiation x-ray tomographic microscopy and the mineralogical characterization of resulting material allows for the comparative volumetric quantification of dissolution and precipitation. The unique design of this experiment allows for the identification of alteration which occurs solely abiotically and of microbially mediated alteration. Experimental results are compared to natural basaltic cores from Iceland retrieved following a large field CO2 injection experiment that stimulated microbial activity at depth.

  10. First fossil evidence of Connaraceae R. Br. from Indian Cenozoic ...

    Indian Academy of Sciences (India)

    This is the first authentic record of the occurrence of leaflet comparable to R. caudata of Connaraceae from the Cenozoic sediments of India and abroad. At present R. caudata does not grow in India and is restricted only in southeast Asia especially in China and Myanmar. This taxon probably migrated to these southeast ...

  11. A re-examination of Cenozoic Polypodium in North America

    Czech Academy of Sciences Publication Activity Database

    Kvaček, Z.; Dašková, Jiřina; Zetter, R.


    Roč. 128, 3/4 (2004), s. 219-227 ISSN 0034-6667 Institutional research plan: CEZ:AV0Z3013912 Keywords : Polypodiaceae * Cenozoic * Palaeobotany Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.886, year: 2004

  12. First fossil evidence of Connaraceae R. Br. from Indian Cenozoic ...

    Indian Academy of Sciences (India)

    First fossil evidence of Connaraceae R. Br. from Indian Cenozoic. 1085 this genus have been studied in order to find out its exact affinity and it is found that only three species of Rourea, viz., R. minor (Gaertner) Leenhouts;. R. microphylla (Hooker and Arnott) Planch. and. R. caudata Planch. come close to the fossil spec-.

  13. Applications of dynamic crystallization studies - Lunar olivine-normative basalts (United States)

    Bianco, A. S.; Taylor, L. A.


    Dynamic crystallization studies were performed on two synthetic glasses similar in composition to the mare olivine-normative basalt samples 12009 and 15555. The effects of viscosity (primarily a function of FeO) and the initial temperature of cooling on mineral chemistry, texture, and temperature of appearance of phases were investigated. Olivine compositions seem to indicate that, for the two types of melt cooled at the same rate, there are no significant differences in the degree of undercooling at which olivine nucleates, but it is found that olivine-nucleated densities differ. The cooling rate of 15555 is estimated. Since the temperature at which cooling is initiated affects texture, mineral chemistry, and temperature of appearance of phases so greatly, caution is recommended in the application of experimental data to natural rock systems.

  14. Thermal Emission Spectra of Silica-coated Basalt and Considerations for Martian Surface Mineralogy (United States)

    Kraft, M. D.; Sharp, T. G.; Michalski, J. R.


    Among the most important discoveries made during the Mars Global Surveyor (MGS) mission was that the rocky materials of Mars are broadly divisible into two distinct rock types. The geological significance of this finding is dependent on the mineralogy of these rock types as well as their geographic and stratigraphic positions. Much work has yet to be done to understand these relationships and the small-scale variability of these units. For now, it is worth considering various scenarios that could have resulted in Mars global-scale mineralogical dichotomy. Such work will make clearer what must be looked for in Thermal Emission Spectrometer (TES) and Thermal Imaging Spectrometer (THEMIS) data, what to test with other data sets, and what geological processes can be considered or ruled out as we advance with interpreting Martian geologic history. Here, we suggest that exogenic coatings of secondary silica on basaltic rocks may provide a plausible explanation for the newly discovered distribution of rock types.

  15. The rock coast of South and Central America : chapter 10


    Blanco-Chao, R.; Pedoja, K.; Witt, C.; Martinod, J.; Husson, L.; Regard, V.; Audin, Laurence; Nexer, M.; Delcaillau, B.; Saillard, M.; Melnick, D.; Dumont, J.F.; Santana, E.; Navarrete, E.; Martillo, C.


    The great variety of climatic conditions, tidal ranges and wave regimes of South and Central America act on a complex geology and tectonic framework. Many of the rock and cliffed coasts of South America are strongly controlled by the occurrence of extensive Cenozoic and Pleistocene sediments that crop out at the coast. Geology and the different uplift rates are a major factor in the whole coastal geomorphology of South and Central America, and consequently are a very important control of the ...

  16. Cenozoic epeirogeny of the Indian peninsula (United States)

    Richards, F. D.; Hoggard, M. J.; White, N. J.


    Peninsular India is a cratonic region with asymmetric relief manifest by eastward tilting from the 1.5 km high Western Ghats escarpment toward the floodplains of eastward-draining rivers. Oceanic residual depth measurements on either side of India show that this west-east asymmetry is broader scale, occurring over distances of > 2000 km. Admittance analysis of free-air gravity and topography shows that the elastic thickness is 10 ± 3 km, suggesting that regional uplift is not solely caused by flexural loading. To investigate how Indian physiography is generated, we have jointly inverted 530 river profiles to determine rock uplift rate as a function of space and time. Key erosional parameters are calibrated using independent geologic constraints (e.g., emergent marine deposits, elevated paleosurfaces, uplifted lignite deposits). Our results suggest that regional tilt grew at rates of up to 0.1 mm a-1 between 25 Ma and the present day. Neogene uplift initiated in the south and propagated northward along the western margin. This calculated history is corroborated by low-temperature thermochronologic observations, by sedimentary flux of clastic deposits into the Krishna-Godavari delta, and by sequence stratigraphic architecture along adjacent rifted margins. Onset of regional uplift predates intensification of the Indian monsoon at 8 Ma, suggesting that rock uplift rather than climatic change is responsible for modern-day relief. A positive correlation between residual depth measurements and shear wave velocities beneath the lithosphere suggests that regional uplift is generated and maintained by temperature anomalies of ±100 °C within a 200 ± 25 km thick asthenospheric channel.

  17. Cenozoic Molluscan types from Java (Indonesia) in the Martin Collection (Division of Cenozoic Mollusca), National Museum of Natural History, Leiden

    NARCIS (Netherlands)

    Hoek Ostende, van den L.W.; Leloux, J.; Wesselingh, F.P.; Winkler Prins, C.F.


    An inventory of type material in the ‘Martin Collection’ at the Division of Cenozoic Mollusca of the National Museum of Natural History, Leiden, The Netherlands has been made. In total 1842 lots containing over 5700 type specimens of 912 species were encountered. The status of the types is outlined.

  18. Geology and petrology of the basalts of Crater Flat: applications to volcanic risk assessment for the Nevada Nuclear Waste Storage investigations

    International Nuclear Information System (INIS)

    Vaniman, D.; Crowe, B.


    Volcanic hazard studies of the south-central Great Basin, Nevada, are being conducted for the Nevada Nuclear Waste Storage Investigations. This report presents the results of field and petrologic studies of the basalts of Crater Flat, a sequence of Pliocene to Quaternary-age volcanic centers located near the southwestern part of the Nevada Test Site. Crater Flat is one of several basaltic fields constituting a north-northeast-trending volcanic belt of Late Cenozoic age extending from southern Death Valley, California, through the Nevada Test Site region to central Nevada. The basalts of Crater Flat are divided into three distinct volcanic cycles. The cycles are characterized by eruption of basalt magma of hawaiite composition that formed cinder cone clusters and associated lava flows. Total volume of erupted magma for respective cycles is given. The basalts of Crater Flat are sparsely to moderately porphyritic; the major phenocryst phase is olivine, with lesser amounts of plagioclase, clinopyroxene, and rare amphibole. The consistent recurrence of evolved hawaiite magmas in all three cycles points to crystal fractionation from more primitive magmas at depth. A possible major transition in mantle source regions through time may be indicated by a transition from normal to Rb-depleted, Sr-enriched hawaiites in the younger basaltic cycles. The recurrence of small volumes of hawaiite magma at Crater Flat supports assumptions required for probability modeling of future volcanic activity and provides a basis for estimating the effects of volcanic disruption of a repository site in the southwestern Nevada Test Site region. Preliminary data suggest that successive basalt cycles at Crater Flat may be of decreasing volume but recurring more frequently

  19. Upper Cretaceous to Pleistocene melilitic volcanic rocks of the Bohemian Massif: Petrology and mineral chemistry

    Czech Academy of Sciences Publication Activity Database

    Skála, Roman; Ulrych, Jaromír; Krmíček, Lukáš; Fediuk, F.; Balogh, K.; Hegner, E.


    Roč. 66, č. 3 (2015), s. 197-216 ISSN 1335-0552 Institutional support: RVO:67985831 Keywords : Bohemian Massif * Cenozoic volcanism * isotope geochemistry * melilitic rock * mineralogy * petrology Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.523, year: 2015

  20. Melilitic rocks of the CECIP - Examples from Vogtland/W-Bohemia (Germany/Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Abratis, M.; Viereck-Goette, L.; Ulrych, Jaromír


    Roč. 72, 12S (2008), A2-A2 ISSN 0046-564X. [Annual V.M. Goldschmidt Conference /18./. 13.07.2008-18.07.2008, Vancouver,] Institutional research plan: CEZ:AV0Z30130516 Keywords : melilitic rock * Bohemian Massif * Central European Cenozoic Igneous Province * W Bohemia * Vogtland Subject RIV: DB - Geology ; Mineralogy

  1. Potential for microbial oxidation of ferrous iron in basaltic glass. (United States)

    Xiong, Mai Yia; Shelobolina, Evgenya S; Roden, Eric E


    Basaltic glass (BG) is an amorphous ferrous iron [Fe(II)]-containing material present in basaltic rocks, which are abundant on rocky planets such as Earth and Mars. Previous research has suggested that Fe(II) in BG can serve as an energy source for chemolithotrophic microbial metabolism, which has important ramifications for potential past and present microbial life on Mars. However, to date there has been no direct demonstration of microbially catalyzed oxidation of Fe(II) in BG. In this study, three different culture systems were used to investigate the potential for microbial oxidation of Fe(II) in BG, including (1) the chemolithoautotrophic Fe(II)-oxidizing, nitrate-reducing "Straub culture"; (2) the mixotrophic Fe(II)-oxidizing, nitrate-reducing organism Desulfitobacterium frappieri strain G2; and (3) indigenous microorganisms from a streambed Fe seep in Wisconsin. The BG employed consisted of clay and silt-sized particles of freshly quenched lava from the TEB flow in Kilauea, Hawaii. Soluble Fe(II) or chemically reduced NAu-2 smectite (RS) were employed as positive controls to verify Fe(II) oxidation activity in the culture systems. All three systems demonstrated oxidation of soluble Fe(II) and/or structural Fe(II) in RS, whereas no oxidation of Fe(II) in BG material was observed. The inability of the Straub culture to oxidize Fe(II) in BG was particularly surprising, as this culture can oxidize other insoluble Fe(II)-bearing minerals such as biotite, magnetite, and siderite. Although the reason for the resistance of the BG toward enzymatic oxidation remains unknown, it seems possible that the absence of distinct crystal faces or edge sites in the amorphous glass renders the material resistant to such attack. These findings have implications with regard to the idea that Fe(II)-Si-rich phases in basalt rocks could provide a basis for chemolithotrophic microbial life on Mars, specifically in neutral-pH environments where acid-promoted mineral dissolution and

  2. High-level waste-basalt interactions. Annual progress report, February 1, 1977--September 30, 1977

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, G.J.; Scheetz, B.E.


    Commercial radioactive waste can be placed under ground in a basalt repository to contain significant amounts of radioactive decay heat for the first hundred or so years, which constitutes the ''thermal period'' of waste isolation, if the feasibility is determined that a basalt geology is a suitable medium for storage of radioactive wastes. Several physical-chemical changes analogous to natural geochemical processes can occur in and around this repository during the thermal period. The waste canister can act as a heat source and cause changes in the mineralogy and properties of the surrounding basalts. Geochemically, this is ''contact metamorphism.'' This phenomenon needs to be investigated because it could affect the behavior of the basalt with regard to migration of long-lived radionuclides away from the immediate repository. It is well known that even the relatively low-grade hydrothermal conditions possible in the repository (temperatures up to 400 degrees Centigrade; pressures up to 300 bars) can cause extensive modifications in rocks and minerals. At the end of the thermal period, the residue of the original waste plus the waste-basalt interaction products would constitute the actual waste form (or ''source term'') subject to the low-temperature leaching and migration processes under investigation in other laboratories. During the last eight months of fiscal year 1977, a program was initiated at The Pennsylvania State University which had as its objective the determination of the nature and implication of any chemical or mineralogical changes in, or interactions between, each candidate radioactive waste form and representative Columbia River Basalt under the various relevant repository conditions during the thermal period. Results of these investigations are given.

  3. High-level waste-basalt interactions. Annual progress report, February 1, 1977--September 30, 1977

    International Nuclear Information System (INIS)

    McCarthy, G.J.; Scheetz, B.E.


    Commercial radioactive waste can be placed under ground in a basalt repository to contain significant amounts of radioactive decay heat for the first hundred or so years, which constitutes the ''thermal period'' of waste isolation, if the feasibility is determined that a basalt geology is a suitable medium for storage of radioactive wastes. Several physical-chemical changes analogous to natural geochemical processes can occur in and around this repository during the thermal period. The waste canister can act as a heat source and cause changes in the mineralogy and properties of the surrounding basalts. Geochemically, this is ''contact metamorphism.'' This phenomenon needs to be investigated because it could affect the behavior of the basalt with regard to migration of long-lived radionuclides away from the immediate repository. It is well known that even the relatively low-grade hydrothermal conditions possible in the repository (temperatures up to 400 degrees Centigrade; pressures up to 300 bars) can cause extensive modifications in rocks and minerals. At the end of the thermal period, the residue of the original waste plus the waste-basalt interaction products would constitute the actual waste form (or ''source term'') subject to the low-temperature leaching and migration processes under investigation in other laboratories. During the last eight months of fiscal year 1977, a program was initiated at The Pennsylvania State University which had as its objective the determination of the nature and implication of any chemical or mineralogical changes in, or interactions between, each candidate radioactive waste form and representative Columbia River Basalt under the various relevant repository conditions during the thermal period. Results of these investigations are given

  4. Hydrochemistry and hydrogeologic conditions within the Hanford Site upper basalt confined aquifer system

    Energy Technology Data Exchange (ETDEWEB)

    Spane, F.A. Jr.; Webber, W.D.


    As part of the Hanford Site Ground-Water Surveillance Project, Flow System Characterization Task. Pacific Northwest Laboratory examines the potential for offsite migration of contamination within the upper basalt confined aquifer system for the US Department of Energy (DOE). As part of this activity, groundwater samples were collected over the past 2 years from selected wells completed in the upper Saddle Mountains Basalt. The hydrochemical and isotopic information obtained from these groundwater samples provides hydrologic information concerning the aquifer-flow system. Ideally, when combined with other hydrologic property information, hydrochemical and isotopic data can be used to evaluate the origin and source of groundwater, areal groundwater-flow patterns, residence and groundwater travel time, rock/groundwater reactions, and aquifer intercommunication for the upper basalt confined aquifer system. This report presents the first comprehensive Hanford Site-wide summary of hydrochemical properties for the upper basalt confined aquifer system. This report provides the hydrogeologic characteristics (Section 2.0) and hydrochemical properties (Section 3.0) for groundwater within this system. A detailed description of the range of the identified hydrochemical parameter subgroups for groundwater in the upper basalt confined aquifer system is also presented in Section 3.0. Evidence that is indicative of aquifer contamination/aquifer intercommunication and an assessment of the potential for offsite migration of contaminants in groundwater within the upper basalt aquifer is provided in Section 4.0. The references cited throughout the report are given in Section 5.0. Tables that summarize groundwater sample analysis results for individual test interval/well sites are included in the Appendix.

  5. Recreating Rocks

    DEFF Research Database (Denmark)

    Posth, Nicole R


    Nicole Posth and colleagues spent a month touring South African rock formations in their quest to understand the origin of ancient iron and silicate layers.......Nicole Posth and colleagues spent a month touring South African rock formations in their quest to understand the origin of ancient iron and silicate layers....

  6. Evolution of porosity and diffusivity associated with chemical weathering of a basalt clast

    Energy Technology Data Exchange (ETDEWEB)

    Navarre-Sitchler, A.; Steefel, C.I.; Yang, L.; Tomutsa, L.; Brantley, S.L.


    Weathering of rocks as a result of exposure to water and the atmosphere can cause significant changes in their chemistry and porosity. In low-porosity rocks, such as basalts, changes in porosity, resulting from chemical weathering, are likely to modify the rock's effective diffusivity and permeability, affecting the rate of solute transport and thus potentially the rate of overall weathering to the extent that transport is the rate limiting step. Changes in total porosity as a result of mineral dissolution and precipitation have typically been used to calculate effective diffusion coefficients through Archie's law for reactive transport simulations of chemical weathering, but this approach fails to account for unconnected porosity that does not contribute to transport. In this study, we combine synchrotron X-ray microcomputed tomography ({mu}CT) and laboratory and numerical diffusion experiments to examine changes in both total and effective porosity and effective diffusion coefficients across a weathering interface in a weathered basalt clast from Costa Rica. The {mu}CT data indicate that below a critical value of {approx}9%, the porosity is largely unconnected in the basalt clast. The {mu}CT data were further used to construct a numerical pore network model to determine upscaled, effective diffusivities as a function of total porosity (ranging from 3 to 30%) for comparison with diffusivities determined in laboratory tracer experiments. By using effective porosity as the scaling parameter and accounting for critical porosity, a model is developed that accurately predicts continuum-scale effective diffusivities across the weathering interface of the basalt clast.

  7. Application of Clinopyroxene Chemistry to Interpret the Physical Conditions of Ascending Magma, a Case Study of Eocene Volcanic Rocks in the Ghohrud Area (North of Isfahan

    Directory of Open Access Journals (Sweden)

    Mohammad Sayari


    Full Text Available Introduction Volcanic rocks with a porphyritic texture have experienced two crystallization stages. The first is slow, resulting in phenocrysts, and the second, which took place at, or near the surface, or during intrusion into a cooler body of rock, result in a groundmass of glass, or fine crystals. The pressure and temperature history of a magma during crystallization is recorded in the chemical composition of the phenocrysts during both stages. These phenocrysts provide valuable data about the physicochemical conditions of the parent magma during the process of crystallization. The composition of clinopyroxene (cpx reflects not only the chemical condition and therefore the magmatic series, but also the physical conditions, i.e., temperature and pressure of a magma at the time when clinopyroxene crystallized. The Ghohrud area lies in the middle part of the Urumieh-Dokhtar Magmatic Arc , which is part of a much larger magmatic province extending in a vast region of convergence between Arabia and Eurasia north of the Zagros-Bitlis suture zone (Dilek et al., 2010. In the Ghohrud area, north of Isfahan, exposed Eocene volcanic rocks belong to the first pulse of Cenozoic volcanism of Iran (Sayari, 2015, ranging in composition from andesitic basalt to basalt. The basaltic rocks of the Ghohrud area are composed mainly of plagioclase phenocrysts surrounded by smaller crystals of clinopyroxene in a groundmass of microlites, glass and opaques. In this study, the clinopyroxene and plagioclase of these rocks were analyzed in order to estimate the physicochemical conditions of the parent magmas. Results Clinopyroxene and plagioclase phenocrysts of nineteen samples were analyzed with the electron microprobe. The chemical compositions of the clinopyroxenes were used to estimate both the chemical evolution and temperature and pressure conditions of the magmas during crystallization, using SCG, a specialized software for clinopyroxene thermobarometry (Sayari

  8. Art Rocks with Rock Art! (United States)

    Bickett, Marianne


    This article discusses rock art which was the very first "art." Rock art, such as the images created on the stone surfaces of the caves of Lascaux and Altimira, is the true origin of the canvas, paintbrush, and painting media. For there, within caverns deep in the earth, the first artists mixed animal fat, urine, and saliva with powdered minerals…

  9. Tectonomorphic evolution of Marie Byrd Land - Implications for Cenozoic rifting activity and onset of West Antarctic glaciation (United States)

    Spiegel, Cornelia; Lindow, Julia; Kamp, Peter J. J.; Meisel, Ove; Mukasa, Samuel; Lisker, Frank; Kuhn, Gerhard; Gohl, Karsten


    The West Antarctic Rift System is one of the largest continental rifts on Earth. Because it is obscured by the West Antarctic Ice Sheet, its evolution is still poorly understood. Here we present the first low-temperature thermochronology data from eastern Marie Byrd Land, an area that stretches 1000 km along the rift system, in order to shed light on its development. Furthermore, we petrographically analysed glacially transported detritus deposited in the marine realm, offshore Marie Byrd Land, to augment the data available from the limited terrestrial exposures. Our data provide information about the subglacial geology, and the tectonic and morphologic history of the rift system. Dominant lithologies of coastal Marie Byrd Land are igneous rocks that intruded (presumably early Paleozoic) low-grade meta-sedimentary rocks. No evidence was found for un-metamorphosed sedimentary rocks exposed beneath the ice. According to the thermochronology data, rifting occurred in two episodes. The earlier occurred between 100 and 60 Ma and led to widespread tectonic denudation and block faulting over large areas of Marie Byrd Land. The later episode started during the Early Oligocene and was confined to western Pine Island Bay area. This Oligocene tectonic activity may be linked kinematically to previously described rift structures reaching into Bellingshausen Sea and beneath Pine Island Glacier, all assumed to be of Cenozoic age. However, our data provide the first direct evidence for Cenozoic tectonic activity along the rift system outside the Ross Sea area. Furthermore, we tentatively suggest that uplift of the Marie Byrd Land dome only started at 20 Ma; that is, nearly 10 Ma later than previously assumed. The Marie Byrd Land dome is the only extensive part of continental West Antarctica elevated above sea level. Since the formation of a continental ice sheet requires a significant area of emergent land, our data, although only based on few samples, imply that extensive

  10. Study of crystallization of a basalt glass

    International Nuclear Information System (INIS)

    Nishimura, Fernando Takahiro; Hashizume, Camila Mina; Toffoli, Samuel Marcio


    Basalt vitreous ceramics posses industrial importance by presenting high mechanical resistance to the abrasion. It was studied the obtention and the crystallization of a glass obtained from a basalt of Campinas, Sao Paulo, Brazil, aiming to develop a material with great abrasive resistance. Fusions were made at 1400 deg Celsius in electrical oven and in alumina crucible, of fine residues of basalt mining. The obtained glass was treated in a crystallization temperature of 880 deg Celsius, determined by DSC, by various time of treatment. The present main crystalline phases, detected by XRD, were the magnesium-ferrite (MgFe 2 O 4 ) and the diopsid Ca(Mg,Fe,Al)(Si,Al) 2 O 6 . Analysing the density by the Archimedes methodology and the DRX it was possible to follow the crystallization kinetic up.

  11. Rock Physics

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke


    Rock physics is the discipline linking petrophysical properties as derived from borehole data to surface based geophysical exploration data. It can involve interpretation of both elastic wave propagation and electrical conductivity, but in this chapter focus is on elasticity. Rock physics is based...... on continuum mechanics, and the theory of elasticity developed for statics becomes the key to petrophysical interpretation of velocity of elastic waves. In practice, rock physics involves interpretation of well logs including vertical seismic profiling (VSP) and analysis of core samples. The results...

  12. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors (United States)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua


    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  13. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors (United States)

    Cox, Sarah B.; Lui, Donovan; Wang, Xin; Gou, Jihua


    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000 deg C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200 deg C, Beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  14. Diachronic Cenozoic wrenching in southwest of the Colombian Basin


    Alfaro, E.; Barrera, Daniel Florencio; Rossello, Eduardo Antonio


    We propose a major Eocene tectonic inversion related to an oblique convergence between Farallon (after Cocos plate) and Caribbean plates in the offshore of Colombian Caribbean. Between EoceneOligocene occurred an extension and another tectonic inversion since Oligocene to Pleistocene. By structural and stratigraphic evidence extracted from seismic, gravity and well data, we identified diverse diachronic Cenozoic deformations related to an important syndepositional wrenching event. Diachronic ...

  15. Recurrent Cenozoic volcanic activity in the Bohemian Massif (Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Dostal, J.; Adamovič, Jiří; Jelínek, E.; Špaček, Petr; Hegner, E.; Balogh, K.


    Roč. 123, 1/4 (2011), s. 133-144 ISSN 0024-4937 R&D Projects: GA AV ČR(CZ) IAA300130902; GA ČR(CZ) GA205/09/1170 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z30120515 Keywords : Bohemian Massif * Cenozoic * alkaline volcanism * paleostress fields * rift * mantle Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.246, year: 2011

  16. Development of micro-scale joints in volcanic rocks under thermal ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging Solutions)

    mal stress induced joints under varying cooling conditions. 2. Micro-scale joints in the Rajmahal volcanics. To study the micro-scale joints in rock systems, fresh samples of olivine basalt were chosen from the Rajmahal Trap of eastern India. The rocks consist of phenocrysts of olivine, clino-pyroxene. (augite) and plagioclase ...

  17. Implications of one-year basalt weathering/reactivity study for a basalt repository environment

    International Nuclear Information System (INIS)

    Pine, G.L.; Jantzen, C.M.


    The Savannah River Laboratory is testing the performance of the Defense Waste Processing Facility glass under conditions representing potential repository environments. For a basalt repository, one of the important issues is how rapidly reducing conditions are re-established after placement of the waste. The objective of this study was to examine the factors affecting the reactivity of the basalt. Construction of a nuclear waste repository in basalt will temporarily perturb the groundwater conditions, creating more oxidizing (air-saturated) conditions than an undisturbed repository system. Reducing conditions can be beneficial to the performance of waste glass and canisters, and may limit the transport of certain radionuclides. The Basalt Waste Isolation Project intends to use a backfill containing crushed basalt to re-establish the reducing conditions of the groundwater. The reactivity of the basalt has been found to be minimal once the fresh crushed surfaces have been weathered and the reactive intergranular glass component has been leached, e.g., by long-term surface storage. Crushing of the basalt for pneumatic emplacement of the backfill should, therefore, occur shortly before placement in the repository. This backfill must contain a minimum of 5 percent reactive fines (<100 mesh), to rapidly achieve reducing conditions. 23 refs., 21 figs., 18 tabs

  18. Hardness of basaltic glass-ceramics

    DEFF Research Database (Denmark)

    Jensen, Martin; Smedskjær, Morten Mattrup; Estrup, Maja


    The dependence of the hardness of basaltic glass-ceramics on their degree of crystallisation has been explored by means of differential scanning calorimetry, optical microscopy, x-ray diffraction, and Vickers indentation. Different degrees of crystallisation in the basaltic glasses were achieved...... by varying the temperature of heat treatment. The predominant crystalline phase in the glass was identified as augite. It was found that the hardness of the glass phase decreased slightly with an increase in the degree of crystallisation, while that of the augite phase drastically decreased....

  19. Dust, volcanic ash, and the evolution of the South Pacific Gyre through the Cenozoic (United States)

    Dunlea, Ann G.; Murray, Richard W.; Sauvage, Justine; Spivack, Arthur J.; Harris, Robert N.; D'Hondt, Steven


    We examine the 0-100 Ma paleoceanographic record retained in pelagic clay from the South Pacific Gyre (SPG) by analyzing 47 major, trace, and rare earth elements in bulk sediment in 206 samples from seven sites drilled during Integrated Ocean Drilling Program Expedition 329. We use multivariate statistical analyses (Q-mode factor analysis and multiple linear regression) of the geochemical data to construct a model of bulk pelagic clay composition and mass accumulation rates (MAR) of six end-members, (post-Archean average Australian shale, rhyolite, basalt, Fe-Mn-oxyhydroxides, apatite, and excess Si). Integrating the results with Co-based age models at Sites U1365, U1366, U1369, and U1370, we link changes in MAR of these components to global oceanographic, terrestrial, and climatic transformations through the Cenozoic. Our results track the spatial extent (thousands of kilometers) of dust deposition in the SPG during the aridification of Australia. Dispersed ash is a significant component of the pelagic clay, often comprising >50% by mass, and records episodes of Southern Hemisphere volcanism. Because both are transported by wind, the correlation of dust and ash MAR depends on the site's latitude and suggests meridional shifts in the position of atmospheric circulation cells. The hydrothermal MARs provide evidence for rapid deposition from the Osbourn Trough spreading ridge before it went extinct. Excess Si MARs show that the abrupt increase in siliceous productivity observed at Site U1371 also extended at least as far north as Sites U1369 and U1370, suggesting large-scale reorganizations of oceanic Si distributions 10-8 Ma in the southern SPG.

  20. Determination of Geochemical Bio-Signatures in Mars-Like Basaltic Environments

    Directory of Open Access Journals (Sweden)

    Karen Olsson-Francis


    Full Text Available Bio-signatures play a central role in determining whether life existed on early Mars. Using a terrestrial basalt as a compositional analog for the martian surface, we applied a combination of experimental microbiology and thermochemical modeling techniques to identify potential geochemical bio-signatures for life on early Mars. Laboratory experiments were used to determine the short-term effects of biota on the dissolution of terrestrial basalt, and the formation of secondary alteration minerals. The chemoorganoheterotrophic bacterium, Burkholderia sp. strain B_33, was grown in a minimal growth medium with and without terrestrial basalt as the sole nutrient source. No growth was detected in the absence of the basalt. In the presence of basalt, during exponential growth, the pH decreased rapidly from pH 7.0 to 3.6 and then gradually increased to a steady-state of equilibrium of between 6.8 and 7.1. Microbial growth coincided with an increase in key elements in the growth medium (Si, K, Ca, Mg, and Fe. Experimental results were compared with theoretical thermochemical modeling to predict growth of secondary alteration minerals, which can be used as bio-signatures, over a geological timescale. We thermochemically modeled the dissolution of the basalt (in the absence of biota in very dilute brine at 25°C, 1 bar; the pH was buffered by the mineral dissolution and precipitation reactions. Preliminary results suggested that at the water to rock ratio of 1 × 107, zeolite, hematite, chlorite, kaolinite, and apatite formed abiotically. The biotic weathering processes were modeled by varying the pH conditions within the model to adjust for biologic influence. The results suggested that, for a basaltic system, the microbially-mediated dissolution of basalt would result in “simpler” secondary alteration, consisting of Fe-hydroxide and kaolinite, under conditions where the abiotic system would also form chlorite. The results from this study demonstrate

  1. Rock Foundations

    National Research Council Canada - National Science Library


    .... Chapter 4 provides guidance on rock mass characterization and classification schemes. Chapters 5 and 6 provide guidance on related topic areas of foundation deformation and settlement and foundation bearing capacity, respectively...

  2. Modes, tempo and spatial variability of Cenozoic cratonic denudation: morphoclimatic constraints from West Africa (United States)

    Beauvais, Anicet; Chardon, Dominique


    After the onset of Gondwana break-up in the Early Mesozoic, the emerged part of the African plate underwent long Greenhouse effect climatic periods and epeirogeny. The last Greenhouse effect period in the Early Cenozoic and the alternation of wet and dry climatic periods since the Eocene enhanced episodes of rock chemical weathering and laterite production, forming bauxites and ferricretes, interrupted by drier periods of dominantly mechanical denudation, shaping glacis [1]. In Sub-Saharan West Africa, this evolution resulted in pulsate and essentially climatically-forced denudation that has shaped an ubiquitous sequence of five stepped lateritic paleosurfaces that synchronously developed over Cenozoic times. The modes, timing and spatial variability of continental denudation of the region are investigated by combining geomorphologic and geochronological data sets. The geomorphologic data set comprises the altitudinal distribution of the lateritic paleosurfaces relicts and their differential elevation from 42 locations in Sub-Saharan West Africa where the sequence (or part of it) has been documented. The geochronological data set consists in the age ranges of each paleosurface tackled by radiometric 39Ar-40Ar dating of the neoformed oxy-hydroxides (i.e., cryptomelane, K1-2Mn8O16, nH2O, [4]) carried by their laterites at the Tambao reference site, Burkina Faso [1, 3]. Five groups of 39Ar-40Ar ages, ~ 59 - 45 Ma, ~ 29 - 24 Ma, ~ 18 - 11.5 Ma, ~ 7.2 - 5.8 Ma, and ~ 3.4 - 2.9 Ma, characterize periods of chemical weathering whereas the time laps between these groups of ages correspond to episodes of mechanical denudation that reflect physical shaping of the paleosurfaces. For the last 45 Ma, the denudation rate estimates (3 to 8 m Ma-1) are comparable with those derived on shorter time scale (103 to 106 y.) in the same region by the cosmogenic radionuclide method [2]. Combined with the geomorphologic data set, these age ranges allow the visualization of the regional

  3. A trachyte-syenite core within a basaltic nest: filtering of primitive injections by a multi-stage magma plumbing system (Oki-Dōzen, south-west Japan) (United States)

    Brenna, Marco; Nakada, Setsuya; Miura, Daisuke; Toshida, Kiyoshi; Ito, Hisatoshi; Hokanishi, Natsumi; Nakai, Shun'ichi


    Oki-Dōzen (Japan) is a Late Miocene (7-5 Ma) intraplate alkalic volcano composed of a central trachytic pyroclastic complex surrounded by a ring-shaped succession of basaltic to trachybasaltic lavas and pyroclastic rocks and dispersed trachytic bodies. The central trachytic complex is in contact with a syenite that was intruded into the basement early Miocene volcano-sedimentary succession. In the centre of the system there are no alkalic basaltic rocks that are correlative of the outer flank ring. We present whole-rock major and trace element chemistry, Sr-Nd-Pb isotopic compositions and petrological data from the central trachytic volcanic complex and the intrusive syenite body, as well as from the outer ring basaltic succession. We also present and discuss a new set of zircon U/Pb ages collected from the central trachyte and syenite bodies. All the eruptive products of Oki-Dōzen, as well as the syenite, plot on a single liquid line of descent initiated from a mantle-derived alkalic basaltic parent. A younger (2.8 Ma) basaltic eruption (Uzuka basalt) has isotopic compositions that distinguish it from the rest of the system. Geochemical modelling indicates that magmatic differentiation through crystal fractionation and minor crustal assimilation occurred in crustal and shallow sub-volcanic magma reservoirs. In the central part of the system, a number of vertically spaced reservoirs acted as a filter, capturing basaltic dykes and hindering their ascent. In the outer region, dykes either reached the surface unhindered and erupted to form the basaltic/trachybasaltic succession or stalled at crustal levels and differentiated to trachyte before forming dispersed domes/flows. The central plumbing system "filter" resulted in a nest-shaped volcano, with a trachytic core surrounded by basaltic products, and stopped direct injection of basaltic magmas into the shallow syenitic magma reservoir, likely preventing its destabilization and explosive eruption.

  4. A combined analysis of basaltic melting and shear wave velocity anomalies to constrain dynamic support of western North America (United States)

    Klöcking, Marthe; White, Nicky; Maclennan, John; Fitton, Godfrey


    The region of western North America that encompasses the Basin and Range Province, the Snake River Plain and the Colorado Plateau is about 2 km higher than cratonic North America. This topographic difference broadly coincides with variations in lithospheric thickness (i.e. Mexico, and inverse modeling of regional drainage networks together suggest that this regional uplift occurred during Cenozoic time in at least two discrete phases. Earthquake tomographic models have imaged low velocity material beneath the bulk of western North America, including a ring-shaped anomaly encompassing the Colorado Plateau itself. Basaltic magmatism coincides with these low velocity zones and indicates an overall increase in melt volume at 40 Ma, as well as an abrupt change from lithospheric to asthenospheric signatures at 5 Ma. To investigate the quantitative relationship between seismic velocity anomalies and basaltic magmatism, we have analyzed >260 samples from volcanic centers throughout western North America for major, trace and rare earth elements using ICP-MS and XRF techniques. For asthenospheric samples, we observe a correlation between slow shear wave velocity anomalies and basaltic geochemistry. Using a combination of petrologic observations, forward and inverse modeling of major and rare earth elements, and shear wave velocity anomalies from tomographic models, we determine depth of melting and melt fraction. We explore the possibility that volatiles, anomalous source composition and/or temperature can give rise to basaltic magmatism and regional uplift. We then calculate mantle temperatures from shear wave velocity profiles beneath each volcanic field. In this way, we exploit a variety of approaches to constrain lithospheric thickness and mantle potential temperature. Our combined geochemical and geophysical results yield excess temperatures of 50-80 °C beneath a 60 km thin lithospheric plate. A dynamic topographic model of progressive lithospheric erosion over

  5. Plasma sprayed basalt/chromium oxide coatings

    Czech Academy of Sciences Publication Activity Database

    Ageorges, H.; Medarhri, Z.; Ctibor, Pavel; Fauchais, P.


    Roč. 11, č. 1 (2007), s. 71-82 ISSN 1093-3611 Institutional research plan: CEZ:AV0Z20430508 Keywords : Chromia, basalt * plasma spraying * microstructure * phase analysis Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.268, year: 2007

  6. Petrography of basalts from the Carlsberg ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Iyer, S.D.

    Petrographic characteristics of basalts collected from a segment of the Carlsberg Ridge (lat. 3 degrees 35'N to 3 degrees 41'N; long. 64 degrees 05'E to 64 degrees 09'E) show typical pillow lava zonations with variable concentrations of plagioclase...

  7. Hydrogen isotope systematics of submarine basalts

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, T.K. (Saskatchewan Univ., Saskatoon (Canada). Dept. of Geological Sciences); O' Neil, J.R. (Geological Survey, Menlo Park, CA (USA))


    The D/H ratios and water contents in fresh submarine basalts from the Mid-Atlantic Ridge, the East Pacific Rise, and Hawaii indicate that the primary D/H ratios of many submarine lavas have been altered by processes including (1) outgassing, (2) addition of seawater at magmatic temperature, and (3) low-temperature hydration of glass. Decreases in deltaD and H/sub 2/O/sup +/ from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between deltaD and H/sub 2/O/sup +/ in basalts from the Galapagos Rise and the FAMOUS Area are attributed to outgassing of CH/sub 4/ and H/sub 2/. A good correlation between deltaD values and H/sub 2/O is observed in a suite of submarine tholeiites dredged from the Kilauea East Rift Zone where seawater (added directly to the magma), affected only the isotopic compositions of hydrogen and argon. Analyses of some glassy rims indicate that the outer millimeter of the glass can undergo low-temperature hydration by hydroxyl groups having deltaD values as low as -100. deltaD values vary with H/sub 2/O contents of subaerial transitional basalts from Molokai, Hawaii, and subaerial alkali basalts from the Society Islands, indicating that the primary deltaD values were similar to those of submarine lavas. The results are discussed.

  8. Basalt: structural insight as a construction material

    Indian Academy of Sciences (India)

    This paper explores the state of the art of basalt used in the construction industry with the overall layout of different subcategories of historical background starting from fibre development and different chemical and mechanical fibre properties to its applications in the field. Comparative studies have also been reported with ...

  9. Thermal models for basaltic volcanism on Io (United States)

    Keszthelyil, L.; McEwen, A.


    We present a new model for the thermal emissions from active basaltic eruptions on Io. While our methodology shares many similarities with previous work, it is significantly different in that (1) it uses a field tested cooling model and (2) the model is more applicable to pahoehoe flows and lava lakes than fountain-fed, channelized, 'a'a flows. This model demonstrates the large effect lava porosity has on the surface cooling rate (with denser flows cooling more slowly) and provides a preliminary tool for examining some of the hot spots on Io. The model infrared signature of a basaltic eruption is largely controlled by a single parameter, ??, the average survival time for a lava surface. During an active eruption surfaces are quickly covered or otherwise destroyed and typical values of ?? for a basaltic eruption are expected to be on the order of 10 seconds to 10 minutes. Our model suggests that the Galileo SSI eclipse data are consistent with moderately active to quiescent basaltic lava lakes but are not diagnostic of such activity. Copyright 1997 by the American Geophysical Union.

  10. Pressure grouting of fractured basalt flows

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, P.; Weidner, J.; Phillips, S.; Alexander, J.


    This report describes a field trial of pressure grouting in basalt and the results of subsequent coring and permeability measurement activities. The objective was to show that the hydraulic conductivity of fractured basalt bedrock can be significantly reduced by pressure injection of cementitious materials. The effectiveness of the pressure grout procedure was evaluated by measuring the change in the hydraulic conductivity of the bedrock. The extent of grout penetration was established by analyzing postgrout injection drilling chips for the presence of a tracer in the grout and also by examining cores of the treated basalt. Downhole radar mapping was used to establish major lava flow patterns and follow water movement during a surface infiltration test. A site called Box Canyon, which is located northwest of the INEL, was chosen for this study due to the similarity of this surface outcrop geology to that of the underlying bedrock fracture system found at the Radioactive Waste Management Complex. This study showed that hydraulic conductivity of basalt can be reduced through pressure grouting of cementitious material.

  11. Increased corrosion resistance of basalt reinforced cement compositions with nanosilica

    Directory of Open Access Journals (Sweden)

    URKHANOVA Larisa Alekseevna


    Full Text Available Disperse fiber reinforcement is used to improve deformation and shrinkage characteristics, flexural strength of concrete. Basalt roving and thin staple fiber are often used as mineral fibers. The paper considers the problems of using thin basalt fiber produced by centrifugal-blow method. Evaluation of the corrosion resistance of basalt fiber as part of the cement matrix was performed. Nanodispersed silica produced by electron beam accelerator was used to increase corrosion resistance of basalt fiber.

  12. Repository site definition in basalt: Pasco Basin, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Guzowski, R.V.; Nimick, F.B.; Muller, A.B.


    Discussion of the regional setting, geology, hydrology, and geochemistry of the Pasco Basin are included in this report. Pasco basin is a structural and topographic basin of approximately 2000 mi/sup 2/ (5180 km/sup 2/) located within the Yakima Fold Belt Subprovince of the Columbia Plateau. The stratigraphic sequence within the basin consists of an undetermined thickness of lower Miocene and younger flood basalts with interbedded and overlying sedimentary units. This sequence rests upon a basement of probably diverse rock types that may range in age from precambrian through early Tertiary. Although a large amount of information is available on the hydrology of the unconfined aquifer system, ground-water flow within the basin is, in general, poorly understood. Recharge areas for the Mabton interbed and the Saddle Mountains Formation are the highlands surrounding the basin with the flow for these units toward Gable Butte - Gable Mountain and Lake Wallula. Gable Butte - Gable Mountain probably is a ground-water sink, although the vertical flow direction in this zone is uncertain. The amount of upward vertical leakage from the Saddle Mountains Formation into the overlying sediments or to the Columbia River is unknown. Units underlying the Mabton interbed may have a flow scheme similar to those higher units or a flow scheme dominated by interbasin flow. Upward vertical leakage either throughout the basin, dominantly to the Columbia River, or dominantly to Lake Wallula has been proposed for the discharge of the lower units. None of these proposals is verified. The lateral and vertical distribution of major and minor ions in solution, Eh and pH, and ion exchange between basalt and ground-water are not well defined for the basin. Changes in the redox potential from the level of the subsurface facility to the higher stratigraphic levels along with the numerous other factors influencing K/sub d/, result in a poor understanding of the retardation process.

  13. Repository site definition in basalt: Pasco Basin, Washington

    International Nuclear Information System (INIS)

    Guzowski, R.V.; Nimick, F.B.; Muller, A.B.


    Discussion of the regional setting, geology, hydrology, and geochemistry of the Pasco Basin are included in this report. Pasco basin is a structural and topographic basin of approximately 2000 mi 2 (5180 km 2 ) located within the Yakima Fold Belt Subprovince of the Columbia Plateau. The stratigraphic sequence within the basin consists of an undetermined thickness of lower Miocene and younger flood basalts with interbedded and overlying sedimentary units. This sequence rests upon a basement of probably diverse rock types that may range in age from precambrian through early Tertiary. Although a large amount of information is available on the hydrology of the unconfined aquifer system, ground-water flow within the basin is, in general, poorly understood. Recharge areas for the Mabton interbed and the Saddle Mountains Formation are the highlands surrounding the basin with the flow for these units toward Gable Butte - Gable Mountain and Lake Wallula. Gable Butte - Gable Mountain probably is a ground-water sink, although the vertical flow direction in this zone is uncertain. The amount of upward vertical leakage from the Saddle Mountains Formation into the overlying sediments or to the Columbia River is unknown. Units underlying the Mabton interbed may have a flow scheme similar to those higher units or a flow scheme dominated by interbasin flow. Upward vertical leakage either throughout the basin, dominantly to the Columbia River, or dominantly to Lake Wallula has been proposed for the discharge of the lower units. None of these proposals is verified. The lateral and vertical distribution of major and minor ions in solution, Eh and pH, and ion exchange between basalt and ground-water are not well defined for the basin. Changes in the redox potential from the level of the subsurface facility to the higher stratigraphic levels along with the numerous other factors influencing K/sub d/, result in a poor understanding of the retardation process

  14. Tracking Hadean processes in modern basalts with 142-Neodymium (United States)

    Horan, M. F.; Carlson, R. W.; Walker, R. J.; Jackson, M.; Garçon, M.; Norman, M.


    The short-lived 146Sm→142 Nd isotope system (t1/2 = 103 Ma) provides constraints on the timing and processes of terrestrial silicate fractionation during the early Hadean. Although some Archean terranes preserve variability in 142Nd/144Nd, no anomalies have been resolved previously in young rocks. This study provides high precision 142Nd/144Nd data on a suite of ocean island basalts from Samoa and Hawaii previously shown to have variable depletions in 182W/184W that are inversely correlated with 3He/4He ratios. Improved analytical techniques and multiple replicate analyses of Nd show a variation in μ142 Nd values between -1.3 and +2.7 in the suite, relative to the JNdi standard. Given the reproducibility of the standard (±2.9 ppm, 2 SD), two Samoan samples exhibit resolved variability in their 142Nd/144Nd ratios outside of their 95% confidence intervals, suggesting minor variability in the Samoan hotspot. One sample from Samoa has a higher μ142 Nd of +2.7, outside the 95% confidence interval (±1.0 ppm) of the average of the JNdi standard. Limited, but resolved, variation in 142Nd/144Nd within the suite suggests the preservation of early Hadean silicate differentiation in the sources of at least some basalts from Samoa. Larger variations of 182W/184W and 3He/4He ratios in the same samples suggest that metal-silicate separation and mantle outgassing left a more persistent imprint on the accessible mantle compared to 142Nd/144Nd ratios which are impacted by early silicate differentiation.

  15. Some thoughts on the origin of lunar ANT-KREEP and mare basalts (United States)

    Wakita, H.; Laul, J. C.; Schmitt, R. A.


    It is suggested that a series of ANT (anorthosite-norite-troctolite)-KREEP type rocks and the source material for mare basalts sampled by Apollo 11, 12, 15, and 17 may have been derived from a common magmatic differentiation. This differentiation is studied on the basis of a model which proposes that, in the early history of the moon, extensive melting occurred in the outer lunar shell and a magma layer of 100-200 km was formed. The presence of a residual liquid which has not yet been sampled is suspected between high-K KREEP and the Apollo 11 basalt materials. This residual liquid would have a FeO/MgO ratio greater than one and would be significantly enriched in apatite, zircon, K-feldspar, and ilmenite minerals.

  16. Geochemical characteristics of the Jos-Plateau Basalts, North ...

    African Journals Online (AJOL)

    The Jos Plateau basalts, present Zr/Nb ratios (2.4-3.0) comparable to those of the alkali basalts of the lower Benue valley, and of the Cameroon volcanic line, suggesting that they were possibly derived from the same mantle source. Keywords: Jos Plateau, alkali basalt, mantle, partial melting, incompatible elements.

  17. A Cenozoic record of the equatorial Pacific carbonate compensation depth

    NARCIS (Netherlands)

    Pälike, H.; Lyle, M.W.; Nishi, H.; Raffi, I.; Ridgwell, A.; Gamage, K.; Klaus, A.; Acton, G.; Anderson, L.; Backman, J.; Baldauf, J.; Beltran, C.; Bohaty, S.M.; Bown, P.; Busch, W.; Channell, J.E.T.; Chun, C.O.J.; Delaney, M.; Dewangan, P.; Jones, T.D.; Edgar, K.M.; Evans, H.; Fitch, P.; Foster, G.L.; Gussone, N.; Hasegawa, H.; Hathorne, E.C.; Hayashi, H.; Herrle, J.O.; Holbourn, A.; Hovan, S.; Hyeong, K.; Iijima, K.; Ito, T.; Kamikuri, S.; Kimoto, K.; Kuroda, J.; Leon-Rodriguez, L.; Malinverno, A.; Moore, T.C.; Murphy, B.H.; Murphy, D.P.; Nakamura, H.; Organe, K.; Ohneiser, C.; Richter, C.; Robinson, R.; Rohling, E.J.; Romero, O.; Sawada, K.; Scher, H.; Schneider, L.; Sluijs, A.; Takata, H.; Tian, J.; Tsujimoto, A.; Wade, B.S.; Westerhold, T.; Wilkens, R.; Williams, T.; Wilson, P.A.; Yamamoto, Y.; Yamamoto, S.; Yamazaki, T.; Zeebe, R.E.


    Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carboninput fromvolcanicandmetamorphicoutgassingandits removalbyweathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The

  18. Field-trip guide to the vents, dikes, stratigraphy, and structure of the Columbia River Basalt Group, eastern Oregon and southeastern Washington (United States)

    Camp, Victor E; Reidel, Stephen P.; Ross, Martin E.; Brown, Richard J.; Self, Stephen


    The Columbia River Basalt Group covers an area of more than 210,000 km2 with an estimated volume of 210,000 km3. As the youngest continental flood-basalt province on Earth (16.7–5.5 Ma), it is well preserved, with a coherent and detailed stratigraphy exposed in the deep canyonlands of eastern Oregon and southeastern Washington. The Columbia River flood-basalt province is often cited as a model for the study of similar provinces worldwide.This field-trip guide explores the main source region of the Columbia River Basalt Group and is written for trip participants attending the 2017 International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) Scientific Assembly in Portland, Oregon, USA. The first part of the guide provides an overview of the geologic features common in the Columbia River flood-basalt province and the stratigraphic terminology used in the Columbia River Basalt Group. The accompanying road log examines the stratigraphic evolution, eruption history, and structure of the province through a field examination of the lavas, dikes, and pyroclastic rocks of the Columbia River Basalt Group.

  19. Natural radioactivity of the rocks from the Moon and planets

    International Nuclear Information System (INIS)

    Surkov, Yu.A.


    Tha data on natural radioactivity of rocks (U, Th and K contents) from the Moon, Venus and Mars obtained by means of cosmic means are analyzed. The Moon rock radioactivity has been measured in situ (from orbital vehicles) as well as in the samples of lunar material delivered to the Earth and as for Venus and Mars rocks - by landing vehicles. It has been found that the main specific feature of the Moon and the Earth group planets is the presence of two geomorphological types of the structure of their surface composed by two different types of the matter. The ancient contineent regions are made up by feldspar rock - gabbroanorthosite at the Moon (and possibly at the Mars) and granite-metamorphic at the Earth (and possibly at the Venus). The younger ''marine'' regions are composed by basalt rock. The presence at the Moon of two types of crust (marine and continental ones) having a different nature is clearly reflected on the Moon radioactivity map where marine regions (15% of the total surface) which have high radioactivity and continental regions with a relatively low radioactivity can be seen. The discovery of rocks on the Venus surface highly enriched by U, Th and K speaks of their melting from the primary matter in the depth of the Earth. The Marsian rock by the natural radioelement content is close to igneous rocks of the Earth crust of the basic composition and lunar marine basalts

  20. Late Cenozoic volcanism, subduction, and extension in the Lassen Region of California, southern Cascade Range (United States)

    Guffanti, Marianne; Clynne, Michael A.; Smith, James G.; Muffler, L. J. P.; Bullen, Thomas D.


    Hundreds of short-lived, small- to moderate-volume, mostly mafic volcanoes occur throughout the Lassen region of NE California and surround five longer-lived, large-volume, intermediate to silicic volcanic centers younger than 3 Ma. Volcanic rocks older than 7 Ma are scarce in the Lassen region. We identify 537 volcanic vents younger than 7 Ma, and we classify these into five age intervals and five compositional categories based on SiO2 content. Maps of vents by age and composition illustrate regionally representative volcanic trends. By 2 Ma, the eastern limit of voicanism had contracted westward toward the late Quaternary arc. Late Quaternary volcanism is concentrated around and north of the silicic Lassen volcanic center. The belt of most recent volcanism (25-0 ka) has been active since at least 2 Ma. Most mafic volcanism is cakalkaline basalt and basaltic andésite. However, lesser volume of low-potassium olivine tholeiite (LKOT), a geochemically distinctive basalt type found in the northern Basin and Range province, also has erupted throughout the Lassen segment of the Cascade arc since the Pliocene. Thus models of the mantle source and tectonic control of LKOT magmatism should be applicable both within and behind the subduction-related arc. Normal faults and linear groups of vents are evidence of widespread crustal extension throughout most of the Lassen region. NNW alignments of these features indicate NNW orientation of maximum horizontal stress (ENE extension), which is similar to the stress regime in the adjacent northwestern Basin and Range and northern Sierra Nevada provinces. The large, long-lived volcanic centers developed just west of a zone of closely spaced NNW trending normal faults. Within that zone of faulting, pervasive ENE extension has precluded growth of large, long-lived crustal magma systems. We interpret the western limit of the zone of NNW trending normal faults as the western boundary of the Basin and Range province where it overlaps

  1. Early Jurassic Carbon and Sodium Sequestration in a CAMP basalt flow (United States)

    Block, K. A.; Puffer, J. H.


    The initial HTQ-type CAMP Orange Mountain Basalt flow, as well as related pillowed flows and the overlying Preakness flows, locally underwent substantial and well documented albitization, chloritization, and sulphate, carbonate, and zeolite mineralization. Layers representing at least 25 vol % of the Orange Mountain Basalt have undergone a major net increase in sodium and carbon content and a major redistribution of magnesium and calcium. Most alteration occurred during the development of a widespread early Jurassic geothermal system similar to the active system of Iceland. In both cases alteration was controlled by active circulation of basin brines through vesicular layers during rapid burial at temperatures that were kept elevated by recurring magmatism. Whole rock Na2O levels typically increased from 2.2 wt. % in unaltered layers to 3.2 wt. % in vesicular layers, and commonly reached levels exceeding 5 wt. %. The environmental implications of the removal of such massive amounts of sodium from the geothermal system on the chlorine budget and the salt content of Early Jurassic lakes are currently being evaluated. Massive amounts of carbon sequestration from the geothermal system may have mitigated an increased burden on the early Jurassic atmosphere where geothermal CO2 may have otherwise been vented at hot springs or solfataras. Calcite amygdules typically account for 5 to 10 vol. % of the vesiculated layers amounting to 66 to 132 kg of CO2 per m3 of basalt. If 25 vol. % of the 160 thick Orange Mountain Basalt is vesiculated that would equate to about 2640 to 5280 kg of CO2 per m2 of basalt. The full extent of calcite enrichment across the entire CAMP province, however, has not yet been determined.

  2. Shallow Miocene basaltic magma reservoirs in the Bahia de Los Angeles basin, Baja California, Mexico (United States)

    Delgado-Argote, Luis A.; García-Abdeslem, Juan


    The basement in the Bahía de Los Angeles basin consists of Paleozoic metamorphic rocks and Cretaceous granitoids. The Neogene stratigraphy overlying the basement is formed, from the base to the top, by andesitic lava flows and plugs, sandstone and conglomeratic horizons, and Miocene pyroclastic flow units and basaltic flows. Basaltic dikes also intrude the whole section. To further define its structure, a detailed gravimetric survey was conducted across the basin about 1 km north of the Sierra Las Flores. In spite of the rough and lineal topography along the foothills of the Sierra La Libertad, we found no evidence for large-scale faulting. Gravity data indicates that the basin has a maximum depth of 120 m in the Valle Las Tinajas and averages 75 m along the gravimetric profile. High density bodies below the northern part of the Sierra Las Flores and Valle Las Tinajas are interpreted to be part of basaltic dikes. The intrusive body located north of the Sierra Las Flores is 2.5 km wide and its top is about 500 m deep. The lava flows of the top of the Sierra Las Flores, together with the distribution of basaltic activity north of this sierra, suggests that this intrusive body continues for 20 km along a NNW-trending strike. Between the sierras Las Flores and Las Animas, a 0.5-km-wide, 300-m-thick intrusive body is interpreted at a depth of about 100 m. This dike could be part of the basaltic activity of the Cerro Las Tinajas and the small mounds along the foothills of western Sierra Las Animas. The observed local normal faulting in the basin is inferred to be mostly associated with the emplacement of the shallow magma reservoirs below Las Flores and Las Tinajas.

  3. Continental Flood Basalts of Bennett Island, East Siberian Sea: High Arctic Geodynamics (United States)

    Tegner, Christian; Pease, Victoria


    Volcanism provides a means of tracing mantle melting events and crustal evolution. The High Arctic includes a rich portfolio of volcanic rocks outcropping in the Circum-Arctic borderlands and imaged geophysically beneath the Alpha-Mendeleev Ridge that have been lumped together as a High-Arctic Large Igneous Province (HALIP). However, the ages (c. 440-60 Ma) and compositions (tholeiitic-alkaline-calc-alkaline) reported varies considerably and geological correlations remain elusive. One of the possible correlative events is the formation of continental flood basalts and sills in the Canadian Arctic Islands, Svalbard, Franz Josef Land and Bennett Island. These flood basalts have previously been linked to mantle plume melting and may represent a short-lived LIP event at c. 124-122 Ma. We present new data for a 350 m thick continental flood basalt succession at Bennett Island examined during fieldwork in Septemer 2013 on a joint Russian (VSEGEI) - Swedish (SWEDARCTIC) expedition to the De Long Archipelago. This volcanic succession is composed of 20 near-horisontal, undeformed flow units overlying a thin sedimentary succession of Cretaceous age (?) including coal seams and possibly volcaniclastic material that, in turn, unconformably overlies a more steeply dipping succession of Cambrian and Ordovician sediments. The flows are thinnest (c. 2-10 m) and aphyric to very-sparsely olivine-phyric in the lower portion. In contrast, the flows in the upper portion are thicker (>20 m) and aphyric to sparsely plagioclase-phyric. We will discuss new petrographic and compositional data for the Bennett Island flood basalts, possibly including new U-Pb age data. The aim is to evaluate their petrogenesis, to discuss their possible correlation to the flood basalt and sill successions of the Canadian Arctic Islands, Svalbard and Franz Josef Land and evaluate the geodynamic evolution of the High Arctic.

  4. Continental flood basalt weathering as a trigger for Neoproterozoic Snowball Earth (United States)

    Cox, Grant M.; Halverson, Galen P.; Stevenson, Ross K.; Vokaty, Michelle; Poirier, André; Kunzmann, Marcus; Li, Zheng-Xiang; Denyszyn, Steven W.; Strauss, Justin V.; Macdonald, Francis A.


    Atmospheric CO2 levels and global climate are regulated on geological timescales by the silicate weathering feedback. However, this thermostat has failed multiple times in Earth's history, most spectacularly during the Cryogenian (c. 720-635 Ma) Snowball Earth episodes. The unique middle Neoproterozoic paleogeography of a rifting, low-latitude, supercontinent likely favored a globally cool climate due to the influence of the silicate weathering feedback and planetary albedo. Under these primed conditions, the emplacement and weathering of extensive continental flood basalt provinces may have provided the final trigger for runaway global glaciation. Weathering of continental flood basalts may have also contributed to the characteristically high carbon isotope ratios (δ13 C) of Neoproterozoic seawater due to their elevated P contents. In order to test these hypotheses, we have compiled new and previously published Neoproterozoic Nd isotope data from mudstones in northern Rodinia (North America, Australia, Svalbard, and South China) and Sr isotope data from carbonate rocks. The Nd isotope data are used to model the mafic detrital input into sedimentary basins in northern Rodinia. The results reveal a dominant contribution from continental flood basalt weathering during the ca. 130 m.y. preceding the onset of Cryogenian glaciation, followed by a precipitous decline afterwards. These data are mirrored by the Sr isotope record, which reflects the importance of chemical weathering of continental flood basalts on solute fluxes to the early-middle Neoproterozoic ocean, including a pulse of unradiogenic Sr input into the oceans just prior to the onset of Cyrogenian glaciation. Hence, our new data support the hypotheses that elevated rates of flood basalt weathering contributed to both the high average δ13 C of seawater in the Neoproterozoic and to the initiation of the first (Sturtian) Snowball Earth.

  5. 3D thermal effect of late Cenozoic erosion and deposition within the Lofoten-Vesterålen segment of the Mid-Norwegian continental margin (United States)

    Maystrenko, Yuriy Petrovich; Gernigon, Laurent; Olesen, Odleiv; Ottesen, Dag; Rise, Leif


    A 3D subsurface temperature distribution within the Lofoten-Vesterålen segment of the Mid-Norwegian continental margin and adjacent areas has been studied to understand the thermal effect of late Cenozoic erosion of old sedimentary and crystalline rocks and subsequent deposition of glacial sediments during the Pleistocene. A lithosphere-scale 3D structural model of the Lofoten-Vesterålen area has been used as a realistic approximation of the geometries of the sedimentary infill, underlying crystalline crust and lithospheric mantle during the 3D thermal modelling. The influence of late Cenozoic erosion and sedimentation has been included during the 3D thermal calculations. In addition, the 3D thermal modelling has been carried out by taking also into account the influence of early Cenozoic continental breakup. The results of the 3D thermal modelling demonstrate that the mainland is generally colder than the basin areas within the upper part of the 3D model. The thermal influence of the early Cenozoic breakup is still clearly recognisable within the western and deep parts of the Lofoten-Vesterålen margin segment in terms of the increased temperatures. The thermal effects of the erosion and deposition within the study area also indicate that a positive thermal anomaly exists within the specific sub-areas where sedimentary and crystalline rocks were eroded. A negative thermal effect occurs in the sub-areas affected by subsidence and subsequent sedimentation. The erosion-related positive thermal anomaly reaches its maximum of more than + 27° C at depths of 17-22 km beneath the eastern part of the Vestfjorden Basin. The most pronounced deposition-related negative anomaly shows a minimum of around -70° C at 17-20 km depth beneath the Lofoten Basin. The second negative anomaly is located within the northeastern part of the Vøring Basin and has minimal values of around -48° C at 12-14 km depth. These prominent thermal anomalies are associated with the sub-areas where

  6. Source rock

    Directory of Open Access Journals (Sweden)

    Abubakr F. Makky


    Full Text Available West Beni Suef Concession is located at the western part of Beni Suef Basin which is a relatively under-explored basin and lies about 150 km south of Cairo. The major goal of this study is to evaluate the source rock by using different techniques as Rock-Eval pyrolysis, Vitrinite reflectance (%Ro, and well log data of some Cretaceous sequences including Abu Roash (E, F and G members, Kharita and Betty formations. The BasinMod 1D program is used in this study to construct the burial history and calculate the levels of thermal maturity of the Fayoum-1X well based on calibration of measured %Ro and Tmax against calculated %Ro model. The calculated Total Organic Carbon (TOC content from well log data compared with the measured TOC from the Rock-Eval pyrolysis in Fayoum-1X well is shown to match against the shale source rock but gives high values against the limestone source rock. For that, a new model is derived from well log data to calculate accurately the TOC content against the limestone source rock in the study area. The organic matter existing in Abu Roash (F member is fair to excellent and capable of generating a significant amount of hydrocarbons (oil prone produced from (mixed type I/II kerogen. The generation potential of kerogen in Abu Roash (E and G members and Betty formations is ranging from poor to fair, and generating hydrocarbons of oil and gas prone (mixed type II/III kerogen. Eventually, kerogen (type III of Kharita Formation has poor to very good generation potential and mainly produces gas. Thermal maturation of the measured %Ro, calculated %Ro model, Tmax and Production index (PI indicates that Abu Roash (F member exciting in the onset of oil generation, whereas Abu Roash (E and G members, Kharita and Betty formations entered the peak of oil generation.

  7. High-Ti type N-MORB parentage of basalts from the south Andaman ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    basalts as sub-alkaline basalts and alkaline basalts. A few samples show basaltic andesite, trachy- basalt, or basanitic chemical composition. High-field strength element (HFSE) geochemistry sug- gests that studied basalt samples are probably derived from similar parental magmas. Al2O3/TiO2 and CaO/TiO2 ratios classify ...

  8. The Formation of Carbonate Minerals and the Mobility of Heavy Metals during Water-CO2-Mafic Rock Interactions

    DEFF Research Database (Denmark)

    Olsson, Jonas

    CarbFix is a pilot project in Iceland created to lock away CO2 through in-situ mineralization in the subsurface. The goal is to dissolve CO2 from the geothermal power plant, Hellisheiði, in water and inject it into basaltic rock formation for permanent storage. The carbonated water dissolves...... the basaltic host rock and liberates cations. Ideally, the cations react with the dissolved CO2 and form long time stable carbonate minerals. However, dissolution of the basaltic rock can lead to mobility of toxic metals, which is a potential threat to groundwater supplies and surface waters. Besides carbonate...... minerals, the reaction products are known to be manifold and reflect the complex composition of the basaltic material. Formation of secondary products, such aluminium and iron (hydr)oxides, are considered undesirable, because (1) they consume the cations that could be used to sequester CO2, thus compete...

  9. Rocking pneumonia. (United States)

    Rijkers, Ger T; Rodriguez Gomez, Maria


    Ever since Chuck Berry coined the term "rocking pneumonia" in his 1956 song "Roll over Beethoven", pneumonia has been mentioned frequently in modern blues and rock songs. We analyzed the lyrics of these songs to examine how various elements of pneumonia have been represented in popular music, specifically the cause of pneumonia, the risk groups, comorbidity (such as the boogie woogie flu), the clinical symptoms, and treatment and outcome. Up to this day, songwriters suggest that pneumonia is caused mainly by the cold and rain and that treatment is hardly possible, aside from a shot of rhythm and blues.

  10. Cenozoic structural evolution of the Argentinean Andes at 34°40'S: A close relationship between thick and thin-skinned deformation Evolución estructural Cenozoica de los Andes Argentinos a los 34°40'S: una estrecha relación entre deformación de piel fina y piel gruesa

    Directory of Open Access Journals (Sweden)

    Martín Turienzo


    Full Text Available In the Argentinean side of the Andes at 34°40'S, the Cenozoic Andean orogeny produced the thick-skinned Malargüe fold-and-thrust belt and the easternmost basement uplift of the Cordillera Frontal. Integrating balanced structural cross-sections with previous studies of Cenozoic synorogenic rocks and 40Ar/39Ar ages of coeval volcanic and subvolcanic rocks, we propose a Miocene to Quaternary sequential structural evolution of this sector of the Andes. Andean deformation in the study area begun around 14.5 Ma with the growth of thick-skinned structures at the western region, formed by large basement wedges that propagated along detachment horizons within the cover generating thin-skinned structures. The development of these genetically linked thick and thin-skinned structures finished with the insertion of a third basement wedge and its associated deformation in cover rocks along the Sosneado thrust, before the extrusion of 10.8 Ma volcanic rocks. These structures imply ~10 km of shortening, representing an important Middle Miocene compressive period (2.7 mm/a. Systems of fractures measured in basement, cover and subvolcanic rocks indicate an E-W direction of compression. A supercritical Coulomb wedge attained after the Middle Miocene deformation, was responsible of new basement-involved faulting into the foreland, the west-dipping Carrizalito thrust. The absence of efficient detachment levels in the cover rocks of the eastern region difficulted the development of large basement wedges and instead important backthrusting occurred in the hangingwall of the Carrizalito thrust. Widespread subvolcanic rocks (10.5 to 5.5 Ma exposed in this region suggest a close relationship between magmatism and antithetic faulting. With continuing compression, the Carrizalito thrust breaks through to the surface thrusting pre-Jurassic and Mesozoic sequences over Cenozoic rocks although in the southern region it remains as a blind thrust. This different configuration

  11. Melilitites and associated alkaline silica-undersaturated rocks of the Vogtland/W-Bohemia (Germany/Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Abratis, M.; Viereck-Goette, L.; Ulrych, Jaromír; Munsel, D.


    Roč. 34, 4/6 (2008), s. 1325145-1325145 ISSN 0161-6951. [International Geological Congress /33./. 06.08.2008-14.08.2008, Oslo ] Institutional research plan: CEZ:AV0Z30130516 Keywords : melilitic rock, * Bohemian Massif, * Central European Cenozoic Igneous Province * W Bohemia * Vogtland Subject RIV: DB - Geology ; Mineralogy

  12. Secondary Sulfate Mineralization and Basaltic Chemistry of Craters of the Moon National Monument, Idaho: Potential Martian Analog

    Energy Technology Data Exchange (ETDEWEB)

    C. Doc Richardson; Nancy W. Hinman; Lindsay J. McHenry; J. Michelle Kotler; Jill R. Scott


    Secondary deposits associated with the basaltic caves of Craters of the Moon National Monument (COM) in southern Idaho were examined using X-ray powder diffraction, X-ray fluorescence spectrometry, Fourier transform infrared spectrometry, and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The secondary mineral assemblages are dominated by Na-sulfate minerals (thenardite, mirabilite) with a small fraction of the deposits containing minor concentrations of Na-carbonate minerals. The assemblages are found as white, efflorescent deposits in small cavities along the cave walls and ceilings and as localized mounds on the cave floors. Formation of the deposits is likely due to direct and indirect physiochemical leaching of meteoritic water through the overlying basalts. Whole rock data from the overlying basaltic flows are characterized by their extremely high iron concentrations, making them good analogs for martian basalts. Understanding the physiochemical pathways leading to secondary mineralization at COM is also important because lava tubes and basaltic caves are present on Mars. The ability of FTICR-MS to consistently and accurately identify mineral species within these heterogeneous mineral assemblages proves its validity as a valuable technique for the direct fingerprinting of mineral species by deductive reasoning or by comparison with reference spectra.

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

    Directory of Open Access Journals (Sweden)

    Faryad Shah Wali


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

  14. Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

    Energy Technology Data Exchange (ETDEWEB)

    Gaffney, A M; Borg, L E; Connelly, J N


    Uranium-lead ratios (commonly represented as {sup 238}U/{sup 204}Pb = {mu}) calculated for the sources of martian basalts preserve a record of petrogenetic processes that operated during early planetary differentiation and formation of martian geochemical reservoirs. To better define the range of {mu} values represented by the source regions of martian basalts, we completed U-Pb elemental and isotopic analyses on whole rock, mineral and leachate fractions from the martian meteorite Queen Alexandra Range 94201 (QUE 94201). The whole rock and silicate mineral fractions have unradiogenic Pb isotopic compositions that define a narrow range ({sup 206}Pb/{sup 204}Pb = 11.16-11.61). In contrast, the Pb isotopic compositions of weak HCl leachates are more variable and radiogenic. The intersection of the QUE 94201 data array with terrestrial Pb in {sup 206}Pb/{sup 204}Pb-{sup 207}Pb/{sup 204}Pb-{sup 208}Pb/{sup 204}Pb compositional space is consistent with varying amounts of terrestrial contamination in these fractions. We calculate that only 1-7% contamination is present in the purified silicate mineral and whole rock fractions, whereas the HCl leachates contain up to 86% terrestrial contamination. Despite the contamination, we are able to use the U-Pb data to determine the initial {sup 206}Pb/{sup 204}Pb of QUE 94201 (11.086 {+-} 0.008) and calculate the {mu} value of the QUE 94201 mantle source to be 1.823 {+-} 0.008. This is the lowest {mu} value calculated for any martian basalt source, and, when compared to the highest values determined for martian basalt sources, indicates that {mu} values in martian source reservoirs vary by at least 100%. The range of source {mu} values further indicates that the {mu} value of bulk silicate Mars is approximately three. The amount of variation in the {mu} values of the mantle sources ({mu} {approx} 2-4) is greater than can be explained by igneous processes involving silicate phases alone. We suggest the possibility that a small

  15. Ultrasonic P- and S-Wave Attenuation and Petrophysical Properties of Deccan Flood Basalts, India, as Revealed by Borehole Studies (United States)

    Vedanti, Nimisha; Malkoti, Ajay; Pandey, O. P.; Shrivastava, J. P.


    Petrophysical properties and ultrasonic P- and S-wave attenuation measurements on 35 Deccan basalt core specimens, recovered from Killari borehole site in western India, provide unique reference data-sets for a lesser studied Deccan Volcanic Province. These samples represent 338-m-thick basaltic column, consisting four lava flows each of Ambenali and Poladpur Formations, belonging to Wai Subgroup of the Deccan volcanic sequence. These basalt samples are found to be iron-rich (average FeOT: 13.4 wt%), but relatively poor in silica content (average SiO2: 47.8 wt%). The saturated massive basalt cores are characterized by a mean density of 2.91 g/cm3 (range 2.80-3.01 g/cm3) and mean P- and S-wave velocities of 5.89 km/s (range 5.01-6.50 km/s) and 3.43 km/s (range 2.84-3.69 km/s), respectively. In comparison, saturated vesicular basalt cores show a wide range in density (2.40-2.79 g/cm3) as well as P-wave (3.28-4.78 km/s) and S-wave (1.70-2.95 km/s) velocities. Based on the present study, the Deccan volcanic sequence can be assigned a weighted mean density of 2.74 g/cm3 and a low V p and V s of 5.00 and 3.00 km/s, respectively. Such low velocities in Deccan basalts can be attributed mainly to the presence of fine-grained glassy material, high iron contents, and hydrothermally altered secondary mineral products, besides higher porosity in vesicular samples. The measured Q values in saturated massive basalt cores vary enormously (Q p: 33-1960 and Q s: 35-506), while saturated vesicular basalt samples exhibit somewhat lesser variation in Q p (6-46) as well as Q s (5-49). In general, high-porosity rocks exhibit high attenuation, but we observed the high value of attenuation in some of the massive basalt core samples also. In such cases, energy loss is mainly due to the presence of fine-grained glassy material as well as secondary alteration products like chlorophaeite, that could contribute to intrinsic attenuation. Dominance of weekly bound secondary minerals might also be

  16. Gusev Rocks Solidified from Lava (Approximate True Color) (United States)


    In recent weeks, as NASA's Mars Exploration Rover Spirit has driven through the basin south of 'Husband Hill,' it has been traversing mainly sand and dune deposits. This week, though, Spirit has been maneuvering along the edge of an arc-shaped feature called 'Lorre Ridge' and has encountered some spectacular examples of basaltic rocks with striking textures. This panoramic camera (Pancam) image shows a group of boulders informally named 'FuYi.' These basaltic rocks were formed by volcanic processes and may be a primary constituent of Lorre Ridge and other interesting landforms in the basin. Spirit first encountered basalts at its landing site two years ago, on a vast plain covered with solidified lava that appeared to have flowed across Gusev Crater. Later, basaltic rocks became rare as Spirit climbed Husband Hill. The basaltic rocks that Spirit is now seeing are interesting because they exhibit many small holes or vesicles, similar to some kinds of volcanic rocks on Earth. Vesicular rocks form when gas bubbles are trapped in lava flows and the rock solidifies around the bubbles. When the gas escapes, it leaves holes in the rock. The quantity of gas bubbles in rocks on Husband Hill varies considerably; some rocks have none and some, such as several here at FuYi, are downright frothy. The change in textures and the location of the basalts may be signs that Spirit is driving along the edge of a lava flow. This lava may be the same as the basalt blanketing the plains of Spirit's landing site, or it may be different. The large size and frothy nature of the boulders around Lorre Ridge might indicate that eruptions once took place at the edge of the lava flow, where the lava interacted with the rocks of the basin floor. Scientists hope to learn more as Spirit continues to investigate these rocks. As Earth approaches the Chinese New Year (The Year of the Dog), the Athena science team decided to use nicknames representing Chinese culture and geography to identify rocks and

  17. Dynamic topography and the Cenozoic carbonate compensation depth (United States)

    Campbell, S. M.; Moucha, R.; Raymo, M. E.; Derry, L. A.


    The carbonate compensation depth (CCD), the ocean depth at which the calcium carbonate accumulation rate goes to zero, can provide valuable insight into climatic and weathering conditions over the Cenozoic. The paleoposition of the CCD can be inferred from sediment core data. As the carbonate accumulation rate decreases linearly with depth between the lysocline and CCD, the CCD can be calculated using a linear regression on multiple sediment cores with known carbonate accumulation rates and paleodepths. It is therefore vital to have well-constrained estimates of paleodepths. Paleodepths are typically calculated using models of thermal subsidence and sediment loading and compaction. However, viscous convection-related stresses in the mantle can warp the ocean floor by hundreds of meters over broad regions and can also vary significantly over millions of years. This contribution to paleobathymetry, termed dynamic topography, can be calculated by modeling mantle flow backwards in time. Herein, we demonstrate the effect dynamic topography has on the inference of the late Cenozoic CCD with an example from the equatorial Pacific, considering sites from IODP Expeditions 320/321. The equatorial Pacific, given its large size and high productivity, is closely tied to the global carbon cycle. Accordingly, long-term changes in the equatorial Pacific CCD can be considered to reflect global changes in weathering fluxes and the carbon cycle, in addition to more regional changes in productivity and thermohaline circulation. We find that, when the dynamic topography contribution to bathymetry is accounted for, the equatorial Pacific CCD is calculated to be appreciably shallower at 30 Ma than previous estimates would suggest, implying a greater deepening of the Pacific CCD over the late Cenozoic.

  18. Cenozoic Methane-Seep Faunas of the Caribbean Region.

    Directory of Open Access Journals (Sweden)

    Steffen Kiel

    Full Text Available We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted 'Joes River fauna' consists mainly of large lucinid bivalves and tall abyssochrysoid gastropods, and the early Miocene carbonate-hosted 'Bath Cliffs fauna' containing the vesicomyid Pleurophopsis, the mytilid Bathymodiolus and small gastropods. Two new Oligocene seep communities from the Sinú River basin in Colombia consist of lucinid bivalves including Elongatolucina, thyasirid and solemyid bivalves, and Pleurophopsis. A new early Miocene seep community from Cuba includes Pleurophopsis and the large lucinid Meganodontia. Strontium isotope stratigraphy suggests an Eocene age for the Cuban Elmira asphalt mine seep community, making it the oldest in the Caribbean region. A new basal Pliocene seep fauna from the Dominican Republic is characterized by the large lucinid Anodontia (Pegophysema. In Trinidad we distinguish two types of seep faunas: the mudstone-hosted Godineau River fauna consisting mainly of lucinid bivalves, and the limestone-hosted Freeman's Bay fauna consisting chiefly of Pleurophopsis, Bathymodiolus, and small gastropods; they are all dated as late Miocene. Four new seep communities of Oligocene to Miocene age are reported from Venezuela. They consist mainly of large globular lucinid bivalves including Meganodontia, and moderately sized vesicomyid bivalves. After the late Miocene many large and typical 'Cenozoic' lucinid genera disappeared from the Caribbean seeps and are today known only from the central Indo-Pacific Ocean. We speculate that the increasingly oligotrophic conditions in the Caribbean Sea after the closure of the Isthmus of Panama in the Pliocene may have been unfavorable for such large

  19. Early Cenozoic Multiple Thrust in the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Zhenhan Wu


    Full Text Available Recently completed regional geological mapping at a scale of 1 : 250,000 or larger across all of the Tibetan Plateau coupled with deep seismic surveys reveals for the first time a comprehensive depiction of the major early Cenozoic thrust systems resulting from the northward subduction of the Indian Continental Plate. These systems define a series of overlapping north-dipping thrust sheets that thickened the Tibetan crust and lead to the rise of the plateau. The few south-dipping thrusts present apparently developed within a sheet when the back moved faster than the toe. Many of the thrusts are shown to extend to the middle-lower crustal depths by seismic data. The regional thrust systems are the Main Central, Renbu-Zedong, Gangdese, Central Gangdese, North Gangdese, Bangoin-Nujiang, Qiangtang, Hohxil, and South Kunlun Thrusts. The minimal southward displacements of the South Kunlun, Hohxil, South Qiangtang, and Central Gangdese Thrusts are estimated to be 30 km, 25 km, 150 km and 50 km, respectively. Deep thrusting began in the Himalaya-Tibetan region soon after India-Eurasia continental collision and led to crustal thickening and subsequent uplift of the Tibetan Plateau during Late Eocene-Early Miocene when the systems were mainly active. The major thrust systems ceased moving in Early Miocene and many were soon covered by lacustrine strata. This activity succeeded in the late Cenozoic to crustal extension and strike-slip movement in the central Tibetan Plateau. The revelation of the full array of the early Cenozoic thrust systems provides a much more complete understanding of the tectonic framework of the Tibetan Plateau.

  20. Immiscible iron- and silica-rich melt in basalt petrogenesis documented in the Skaergaard intrusion

    DEFF Research Database (Denmark)

    Jakobsen, Jakob Kløve; Veksler, Ilya; Tegner, Christian


    Silicate liquid immiscibility in basalt petrogenesis is a contentious issue. Immiscible iron and silica-rich liquids were reported in melt inclusions of lunar basalt and in groundmass glasses of terrestrial volcanics. In fully crystallized plutonic rocks, however, silicate liquid immiscibility has...... colored type contains 30.9 6 4.2 wt% FeOt and 40.7 6 3.6 wt% SiO2, whereas the light colored type contains 8.6 6 5.9 wt% FeOt and 65.6 6 7.3 wt% SiO2. Similar light colored melt inclusions in olivine and fine grained dark and light colored interstitial pockets also give evidence of crystallization from...... petrogenesis. Some granitic rocks may represent unmixed silica-rich melt, whereas the dense, iron-rich melt is likely to sink in the crust and could mix with hot mantle-derived magma to form unusual rocks, like ferropicrites, otherwise interpreted as products of heterogeneous mantle sources....

  1. Iridium content of basaltic tuffs and enclosing black shales of the balder formation, North Sea (United States)

    Crawford Elliott, W.; Aronson, James L.; Millard, Hugh T., Jr.


    The anomalous levels of Ir and the presence of shocked metamorphosed quartz deposited at the Cretaceous/Tertiary (K/T) boundary worldwide is strong evidence that a meteorite impact took place during the K/T boundary interval. However, because of observed high Ir contents at Kilauea vents, it is still a major point of contention that the Ir anomaly could have been produced by flood basaltic volcanism. This might especially be true at Stevns Klint, Denmark, where the K/T boundary marl contains pyroclastic labradorite and Mg-smectite thought to have been produced by basaltic volcanism. However, up to now, no study has determined whether or not a depositional Ir anomaly has formed in association with a known major basaltic eruption. Herein, we report the concentrations of Ir, Pt, Au, and Ag in basaltic tuffs and enclosing marine black shales of the widespread Paleocene-Eocene Balder Formation. The tuffs in the Balder Formation represent explosive basaltic volcanism associated with the major volcano/tectonic activity of the opening of the northern North Atlantic Ocean. As such, they are the kind of eruption that could have possibly created a global K/T boundary-type Ir anomaly. Our results show that the tuffs and the shales on a per-weight basis both contain concentrations of Ir (0.1-0.25 ppb) that are higher than the Ir levels recently measured from terrestrial rocks including the Deccan Trap and Columbia River flood basalts, but are comparable to Hawaiian and Reunion Island basalts. Because of its thickness, the absolute amount of Ir expelled during the eruption of the main tuff sequence of the Balder Tuff is sizable. Yet for such an eruption to have produced a global Ir anomaly would mandate it having been one of an extremely high volatile content and it would have to have been erupted over a very short interval of time. Furthermore, such a high proportion of the volatilized Ir would have to have been injected into the stratosphere so that only small enrichments of

  2. Patterns of Cenozoic sediment flux from western Scandinavia

    DEFF Research Database (Denmark)

    Gołędowski, Bartosz; Nielsen, S.B.; Clausen, O.R.


    The significance of variations in the sediment flux from western Scandinavia during the Cenozoic has been a matter of debate for decades. Here we compile the sediment flux using seismic data, boreholes and results from other publications and discuss the relative importance of causal agents such a...... to the world’s oceans. Furthermore, the large variations in the size of sediment catchment areas as well as the possibility of submarine and glacial erosion must be incorporated to understand regional variations in climate driven sediment flux....

  3. Early Cenozoic Multiple Thrust in the Tibetan Plateau


    Zhenhan Wu; Peisheng Ye; Patrick J. Barosh; Daogong Hu; Lu Lu


    Recently completed regional geological mapping at a scale of 1 : 250,000 or larger across all of the Tibetan Plateau coupled with deep seismic surveys reveals for the first time a comprehensive depiction of the major early Cenozoic thrust systems resulting from the northward subduction of the Indian Continental Plate. These systems define a series of overlapping north-dipping thrust sheets that thickened the Tibetan crust and lead to the rise of the plateau. The few south-dipping thrusts pres...

  4. Mid-IR Reflectance (DRIFT) Spectral Variations in Basaltic Mineralogy with Direction of Impact at Lonar Crater, India (United States)

    Basavaiah, N.; Chavan, R. S.; Arif, M.


    Identification of spectral changes with the direction of impact has important implications for understanding the impact cratering phenomenon occurring on both terrestrial and extraterrestrial planets and also for geology of the crater. Fortuitously, Lonar Impact Crater (India) is the only well-preserved terrestrial simple crater excavated on Deccan basalts and serves as an excellent analogue to craters on Mars and Moon. An ~570 ka old Lonar crater was suggested to be formed by an oblique impact of a chondritic impactor that struck the pre-impact target from the east into a sequence of six basaltic Deccan flows and created a 1.88 km diameter crater with two layers of ejecta blanket. Here we report preliminary laboratory studies of spectral results on fine-grained rock powers (IR (4000-400 cm-1) Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. The basalts were collected from two profiles in the east and south sections of the crater wall and the upper most crater rim, which later subdivided into sector-wise samples to carry out a systematic study of spectral properties of Lonar basalts, together with impact related samples of breccias and impact melts. For the first time, data of the shock metamorphism of Lonar basalt is examined using DRIFT spectroscopy. Infrared spectra of rock powders of relatively unshocked and shocked basalts are obtained to document the mineralogical variations and the distribution of primary (e.g. Plagioclase Feldspar, Pyroxene), and secondary Phyllosilicate minerals (e.g. Illite, Smectite, Montmorillonite, Saponite, Serpentine) with direction of impact. The spectral data between pre-impact unshocked and post-impact shocked basalts are interpreted to reflect the effect of shock pressure and alteration that rock have undergone. On western crater rim sector, typical silicate spectral features in 900-1200 cm-1 which attributed to Si-O stretching, are observed to change slightly in the width and shift in position as a result of

  5. Cenozoic Plate tectonic history of the northern Venezuela-Trinidad Area (United States)

    Erlich, Robert N.; Barrett, S. F.


    Geological and geophysical data, coupled with recent plate tectonic reconstructions, suggest that the Cenozoic geologic history of the northern Venezuela-Trinidad area has been dominated by strike-slip displacement of discrete crustal blocks. Allochthonous terranes within the area include metavolcanic rocks of the Cretaceous Villa de Cura Group and metamorphic rocks of the Precambrian to Cretaceous Cordillera de la Costa. A relatively competent crustal block (Margarita Block) is defined by an outline around the metamorphic basement of Margarita Island, the Araya/Paria peninsula, the Northern Range of Trinidad, and Tobago Island. Reconstruction of the Margarita Block to its original position requires at least partial closure of the Falcon Basin, closure of the Bonaire and Cariaco basins, and restoration of about 50 km of motion on both the Oca and Bocono faults. Post middle Eocene eastward translation of the Caribbean plate caused eastward motion of the Margarita Block. A minor change in relative plate motion during the late Oligocene or early Miocene produced a right step in the Moron fault, forming the Cariaco pull-apart basin and El Pilar fault zone. Maximum offset on El Pilar fault is estimated to be no more than 125 km, though displacement along the entire fault zone may have been greater. Transpressional stresses between the Caribbean plate and northern South America caused folding of the Serrania del Interior of Venezuela and the Central Range of Trinidad. Eastward migration of transpressional stresses at the southeastern corner of the Caribbean-South American plate boundary is being accommodated by formation of oblique thrusts, transpressive anticlines, and downwarping of the crust. Bouguer gravity data suggest that Jurassic-aged Atlantic oceanic crust is being depressed as the Caribbean plate expands into the Demerara Plateau area. This study suggests that the faults and transtensional/transpressional/compressional structures identified in this study are

  6. Intellektuaalne rock

    Index Scriptorium Estoniae


    Briti laulja-helilooja ja näitleja Toyah Willcox ning Bill Rieflin ansamblist R.E.M. ja Pat Mastelotto King Krimsonist esinevad koos ansamblitega The Humans ja Tuner 25. okt. Tallinnas Rock Cafés ja 27. okt Tartu Jaani kirikus

  7. Igneous Rocks (United States)

    Doe, Bruce R.

    “Igneous Rocks was written for undergraduate geology majors who have had a year of college-level chemistry and a course in mineralogy … and for beginning graduate students. Geologists working in industry, government, or academia should find this text useful as a guide to the technical literature up to 1981 and as an overview of topics with which they have not worked but which may have unanticipated pertinence to their own projects.” So starts the preface to this textbook.As one who works part time in research on igneous rocks, especially as they relate to mineral deposits, I have been looking for such a book with this avowed purpose in a field that has a choking richness of evolving terminology and a bewildering volume of interdisciplinary literature. In addition to the standard topics of igneous petrology, the book contains a chapter on the role of igneous activity in the genesis of mineral deposits, its value to geothermal energy, and the potential of igneous rocks as an environment for nuclear waste disposal. These topics are presented rather apologetically in the preface, but the author is to be applauded for including this chapter. The apology shows just how new these interests are to petrology. Recognition is finally coming that, for example, mineral deposits are not “sports of nature,” a view held even by many economic geologists as recently as the early 1960's; instead they are perfectly ordinary geochemical features formed by perfectly ordinary geologic processes. In fact, the mineral deposits and their attendant alteration zones probably have as much to tell us about igneous rocks as the igneous rocks have to tell us about mineral deposits.

  8. Biogenic Mn-Oxides in Subseafloor Basalts. (United States)

    Ivarsson, Magnus; Broman, Curt; Gustafsson, Håkan; Holm, Nils G


    The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments.

  9. Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?

    NARCIS (Netherlands)

    Hoareau, G.; Bomou, B.; Van Hinsbergen, D. J J; Carry, N.; Marquer, D.; Donnadieu, Y.; Le Hir, G.; Vrielynck, B.; Walter-Simonnet, A. V.


    The 58-51 Ma interval was characterized by a long-term increase of global temperatures (+4 to +6°C) up to the Early Eocene Climate Optimum (EECO, 52.9-50.7 Ma), the warmest interval of the Cenozoic. It was recently suggested that sustained high atmospheric pCO2, controlling warm early Cenozoic

  10. Feedbacks of lithosphere dynamics and environmental change of the Cenozoic West Antarctic Rift System.

    NARCIS (Netherlands)

    van der Wateren, F.M.; Cloetingh, S.A.P.L.


    This special issue of Global and Planetary Change contains 11 contributions dealing with various aspects of the Cenozoic West Antarctic Rift System. During the last two decades, investigations of the interplay of tectonics and climate greatly improved understanding of Cenozoic global change. Major

  11. Heritage stones and their deterioration in rock-cut monuments in India (United States)

    Sharma, Vinod K.


    India is dotted with thousands of rock- cut monuments of considerable antiquity having artwork of global importance. It is evident from the location of many of these monuments that knowledge of viable selection of site, geotechnical considerations and amenability to sculptures' chisel was vital for construction of rock-cut monuments and sculptures. These rock-cut structures also represent significant achievements of geotechnical and structural engineering and craftsmanship of contemporary period. The paper deals with some of the sites where natural rock-mass exposures were used to hew the monuments and highlight the deterioration owing to geological and climatic conditions. The Kailash temple in Ellora and Ajanta rock-cut caves are among the greatest architectural feats which owe their grandeur to amenability and consistency of basalt of Deccan Volcanic Province from which it is hewn. The Kailash Temple was created through a single, huge top-down excavation 100 feet deep down into the volcanic basaltic cliff rock. These ancient rock cut structures are amazing achievements of structural engineering and craftsmanship. The lava flows are nearly horizontal, competent rock medium facilitated the chiseling for the sculptures. The deterioration of these basalts are seen where the amygdule, vesicles and opening in rock discontinuity had the medium of construction or excavation. The monolithic rock- cut monuments of Mahabalipuram temples are constructed in the form of rathas or chriot and adjoining caves by excavating solid charnockite/granites. The large rock exposures are excavated and cut to perfection with wall decorations and sculptured art. The charnockites are the strongest and the most durable rock, yet quite amenable to fine dressing. These monolithic monuments in charnockite and are cut out of the hillock. The 7th Century monuments now exhibit somewhat rough surface probably due to weathering effect of salt laden winds from the sea side and alteration of feldspars

  12. Structural relaxation in annealed hyperquenched basaltic glasses

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, John C.; Potuzak, M.


    The enthalpy relaxation behavior of hyperquenched (HQ) and annealed hyperquenched (AHQ) basaltic glass is investigated through calorimetric measurements. The results reveal a common onset temperature of the glass transition for all the HQ and AHQ glasses under study, indicating that the primary...... relaxation is activated at the same temperature regardless of the initial departure from equilibrium. The analysis of secondary relaxation at different annealing temperatures provides insights into the enthalpy recovery of HQ glasses....

  13. Hydrologic modeling of the Columbia Plateau basalts

    International Nuclear Information System (INIS)

    Dove, F.H.; Cole, C.R.; Bond, F.W.; Zimmerman, D.A.


    The Office of Nuclear Waste Isolation (ONWI) directed the Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program to conduct a technology demonstration of current performance assessment techniques for the Department of Energy (DOE) as applied to a nuclear waste repository in the Columbia Plateau Basalts. Hypothetical repository coordinates were selected for an actual geographical setting on the Hanford Reservation in the state of Washington. Published hydrologic and geologic data used in the analyses were gathered in 1979 or earlier. The hydrologic simulation was divided into three major parts: (1) aquifer recharge calculations, (2) a regional hydrologic model, and (3) a local hydrologic model of the Pasco Basin. The presentation discusses the regional model. An estimate of the amount of water transmitted through the groundwater system was required to bound the transmissivity values and to estimate the transmissivity distributions for the deeper basalts. The multiple layer two-dimensional Variable Thickness Transient (VTT) code was selected as appropriate for the amount of data available and for the conditions existing in the regional systems. This model uses a finite difference formulation to represent the partial differential flow equation. The regional study area as defined for the VTT model was divided into 55 by 55 square pattern with each grid 5 kilometers on a side. The regional system was modeled as a held potential surface layer and two underlying basalt layers. The regional model established the boundary conditions for the hydrologic model the Pasco Basin

  14. Thermal-Mechanical Regime beneath Tarim Basin, Northwestern China and its Implications for Cenozoic Tectonics (United States)

    Liu, S.; Wang, L.


    As one of the super-large scale sedimentary basins in China, the Tarim basin is also the strategic basement for Chinese `Natural gas transportation from west to east' project. To know its thermal regime is vital for understanding the deformation and oil gas resource in Tarim basin. Integrated the abundant data of geotemperature and rock thermophysical parameters collected and measured in the basin with corresponding geothermal modeling, here we present the characteristics of geotemperature field, thermal evolution and lithospheric thermo-rheological structure of the Tarim basin, along with the implications for formation and deformation of basin and hydrocarbon reservoir. Our results show that the average present-day heat flow of the basin is about 45 mW/m2 and 18-20°/km for geotemperature gradient, respectively. The basin is characterized by lower temperature in a whole. Lateral heterogeneities exist for the distribution of geotemperature field in the basin. The structural units of basin differ much in the geothermal features; generally, the depression areas are of relatively low geotemperature while high for those uplifts and highs in the basin. Thermal evolution modeling of the basin indicated that it has experienced four different phases since basin formation as follows: high heat flow phase from Sinian to Ordovician, thermal attenuation phase during Silurian to late Paleozoic, then stable thermal evolution phase in Mesozoic, and flexural deformation of lithosphere in Cenozoic. The thickness of the thermal lithosphere of basin is 168-192 km, and 25-28km for the crustal brittle-ductile transition depth; the total lithospheric strength is 1.6-7.8*10**13 N/m. The lithosphere beneath basin is characterized by the rigid block with low temperature but large strength, and deform in a whole. Responded to the far field effect of the Cenozoic India-Eurasia collision, the lithosphere beneath Tarim basin is characterized by flexure deformation, resulting in the intensive

  15. Study on Sr-Nd isotopes of mesozoic-cenozoic granites in Qinghai-Tibetan plateau

    International Nuclear Information System (INIS)

    Qiu Ruizhao; Deng Jinfu; Zhou Su; Xiao Qinghui; Cai Zhiyong


    Mesozoic-Cenozoic magmatic activities were intensive in Qinghai-Tibetan plateau. Nd-Sr isotopic compositions of representative granitic plutons in western Qinghai-Tibetan plateau are reported in this paper. Combining with past isotopic data, which has reported in eastern Qinghai-Tibetan plateau, Sr-Nd isotopic compositions and material source and genesis of Mesozoic and Cenozoic granites in Qinghai-Tibetan plateau have been studied. The research result indicates there are three types of granite existing in Qinghai-Tibetan plateau, the granites of Late stage of Yanshan Period which distributing on north and south boundary of Gandes block (namely in north and south granitic belts of Dangdes) and cause of oceanic crust subduction, have ( 87 Sr/ 86 Sr)i of 0.7041-0.7064, ε (Nd) t of +2.5 - +5.7 and TDM age of 312-562 Ma, positive ε Nd, low ( 87 Sr/ 86 Sr)i ratio and young Nd model ages suggest relatively high contents of mantle-derived components in their sources, and this type granite might melt from subduction oceanic crust. The granites occurred intra-Gangdes block which were caused by collision of continent and post-collision, have ( 87 Sr/ 86 Sr)i of 0.706-0.719, ε (Nd) t of -5.3 - -8.3 and TDM age of 1323-1496 Ma, negative ε Nd, relative high ( 87 Sr/ 86 Sr)i ratio with an mid-Proterozoic Nd model ages, suggest granite has the mixing genesis of mantle-derived components and old crustal components in their sources. With relatively small variation range in ε (Nd) t and TDM age, it might imply granitic isotopic source in Gandes block to keep relative homogenization in long period. The granites in Himalayan block which there is not oceanic material to join in melting and to cause of intra-continental subduction, has most ( 87 Sr/ 86 Sr)i ratio more than 0.720, ε (Nd) t of -10.3 - -16.3 and TDM age of 1792-2206 Ma, high ( 87 Sr/ 86 Sr)i ratio, low negative ε (Nd)t with old Nd isotopic model ages and consistent with the Sr, Nd isotopic compositions of basement

  16. Crystallization of tholeiitic basalt in Alae Lava Lake, Hawaii (United States)

    Peck, D.L.; Wright, T.L.; Moore, J.G.


    . Ferric-ferrous ratios suggest that oxidation with maximum intensity between 550??C and 610??C moved downward in the crust as it cooled; this was followed by reduction at a temperature of about 100??C. The crystallized basalt is a homogeneous fine-grained rock containing on the average 48.3 percent by volume intergranular pyroxene (augite > pigeonite), 34.2 percent plagioclase laths (An60 70), 7.9 percent interstitial glass, 6.9 percent opaques (ilmenite > magnetite), 2.7 percent olivine (Fo70 80), and a trace of apatite. Chemical analyses of 18 samples, ranging from initially quenched pumice to lava cored more than a year after the eruption from the center and from near the base of the lake, show little variation from silica-saturated tholeiitic basalt containing 50.4 percent SiO2, 2.4 percent Na2O, and 0.54 percent K2O. Apparently there was no significant crystal settling and no appreciable vapor-phase transport of these components during the year of crystallization. However, seven samples of interstitial liquid that had been filter-pressed into gash fractures and drill holes from partly crystalline mush near the base of the crust show large differences from the bulk composition of the solidified crust-lower MgO, CaO, and Al2O3; and higher total iron, TiO2, Na2O, K2O, P2O5, and F, and, in most samples, SiO2. The minor elements Ba, Ga, Li, Y, and Yb and possibly Cu tend to be enriched in the filter-pressed liquids, and Cr and possibly Ni tend to be depleted. ?? 1966 Stabilimento Tipografico Francesco Giannini & Figli.

  17. Geochemical and isotopic constraints on the genesis of the Jueluotage native copper mineralized basalt, Eastern Tianshan, Northwest China (United States)

    Zhang, Dayu; Zhou, Taofa; Yuan, Feng; Fiorentini, Marco L.; Said, Nuru; Lu, Yongjun; Pirajno, Franco


    The Jueluotage native copper mineralized basalt is located in the Jueluotage Volcanic-sedimentary Belt, Eastern Tianshan, Xinjiang Uygur Autonomous region. The basalt, amygdaloidal basalt and tuff, which host native copper mineralization, were erupted in the lower strata of the Late Carboniferous Matoutan Formation. Whole-rock geochemistry shows that the basaltic occurrences at Shilipo, Heilongfeng, Changchengshan and Dongjianfeng have fractionated chondrite-normalized REE distributions and distinctly negative primitive mantle-normalized Nb, Ta and Ti anomalies. The whole-rock strontium, neodymium and lead isotopic data indicate low εSr(t) (-7.9 to +23.6), high εNd(t) (+2.5 to +7.1), with restricted 206Pb/204Pb (18.152-18.491), 207Pb/204Pb (15.521-15.562) and 208Pb/204Pb (37.978-38.251) ranges. On the basis of these data, we report that the Cu-bearing basalt is associated with high-iron tholeiitic basalts that were sourced from depleted continental lithosphere mantle garnet-bearing peridotite. The primary magma of the Cu-bearing basalt was: (1) relatively low in silica and magnesium; and (2) underwent only slight olivine and clinopyroxene crystal fractionation during the magmatic evolution process. In the Jueluotage belt, the Shilipo basalt lavas display significant geochemical similarities to numerous mafic intrusions that are present throughout the Jueluotage belt. Those mafic lavas and intrusions probably represent successive pulses of mafic magmatism, which lasted between ca. 310 and 270 Ma. A crucial empirical observation is that the Jueluotage volcanic-sedimentary belt is a well-known metallogenic province that contains a wide range of copper, nickel, gold, and iron mineral deposits. These mineral systems were formed at different times and are associated with radically different ore-forming processes. However, they are all within the Jueluotage belt, which is interpreted to be a suture zone between the Junggar and Tarim plates, northwestern China. We

  18. The new Wallula CO2 project may revive the old Columbia River Basalt (western USA) nuclear-waste repository project (United States)

    Schwartz, Michael O.


    A novel CO2 sequestration project at Wallula, Washington, USA, makes ample use of the geoscientific data collection of the old nuclear waste repository project at the Hanford Site nearby. Both projects target the Columbia River Basalt (CRB). The new publicity for the old project comes at a time when the approach to high-level nuclear waste disposal has undergone fundamental changes. The emphasis now is on a technical barrier that is chemically compatible with the host rock. In the ideal case, the waste container is in thermodynamic equilibrium with the host-rock groundwater regime. The CRB groundwater has what it takes to represent the ideal case.

  19. Eurasia as the scene of the Late Cenozoic tectogenesis

    Directory of Open Access Journals (Sweden)

    G.F. Ufimtsev


    Full Text Available This paper attempts to review the descriptions on the genetic series of neotectonic forms in Eurasia. Morphotectonically, the Eurasian continental block exhibits a radial-concentric pattern consisting of four kinds of tectonic units: platforms, rejuvenated and youthful mobile belts, and the continent-ocean transition zones. Vast areas of young and ancient platforms, such as Siberia, have experienced slow-rate Late-Cenozoic uplift and little interior deformation. The youthful orogenic belts are clustered into the giant Alpine-Himalayan megabelt. The rejuvenated mountain belts are characterized by a variety of structural-morphological types of orogens, such as domelike uplifts, block uplifts and intermountain basins. The continent-ocean transition zones in Eastern Asia, including marginal rifts and extensional basins, are resulted from interaction between the continental block and Pacific Ocean and Philippine Sea since the Late Cenozoic. One of the conspicuous features of Eurasia is that most areas lie in the largest geoid depression of the Earth, and the NS trending Uralian-Oman lineament expresses a break on the geoid slope, implying a relationship to deep structure, including density inhomogeneities, downward to the core-mantle interface. Besides, the Eurasian continent fully demonstrates morphotectonic and recent geodynamic features of the Northern Hemisphere of the Earth, just in contrast to that of the Southern Hemisphere. It is best to view the surface morphotectonics and deep structure of the Earth as a geodynamic ensemble which has spawned the large-scale geomorphic features on the surface.

  20. Slab-derived melt involvement in petrogenesis of the high-Nb basalts and magnesian andesites-dacites from NE Iran (United States)

    Ahmadi, Parham; Ghorbani, Mohammad Reza; Coltorti, Massimo; Kuritani, Takeshi; Cai, Yue; Fioretti, Anna Maria; Braschi, Eleonora; Giacomoni, Pier Paolo; Babazadeh, Shahrouz; Conticelli, Sandro


    Tertiary volcanic rocks in NW Firoozeh region, also known as Meshkan triangular structural unit, represent an episode of Tertiary post-collisional magmatism in NE Iran. The volcanic suite is made of Magnesian andesites to dacites associated with some high-Nb basalts. Despite a rather restricted range of emplacement age, variable from 24.1 to 21.7 Ma obtained on the basis of 40Ar-39Ar dating. Major and trace element data show that Firoozeh volcanic rocks were derived from two distinct parental magmas. The dominant high magnesian magmatic series constitutes a wide spectrum of volcanic rocks from andesite to dacite. The magnesian andesites-dacites are subalkaline and characterized by rather high MgO, Ni, Cr and Sr/Y ratio. High Sr/Y ratio of the magnesian andesites-dacites as well as their Sr-Nd isotopic composition support the notion that the magnesian andesites were originated by interaction of slab derived melts with overlying mantle wedge. Fractional crystallization of an amphibole and plagioclase mineral assemblage is found responsible for evolutionary path form the magnesian andesite to more evolved rocks. In contrast to the sabalkaline magnesian andesites- dacites, the high Nb basalts are sodic alkaline rocks and show silica-undersaturated degree. The high-Nb basalts are enriched in Nb, and a wide range of incompatible trace elements that include LILE, LREE. Almost identical Sr-Nd isotopic composition of the magnesian andesites-dacites and high-Nb basalts imply that the two magmatic series has probably shared a common mantle source. Generation of parental magmas of the two magmatic series are attributed to the asthenospheric upwelling and subsequent partial melting of mantle metasomatized by slab-derived melts. Key words: slab melt, High-Nb basalt, 40Ar/39Ar, High-Mg andesite

  1. White Rock (United States)


    14 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the famous 'White Rock' feature in Pollack Crater in the Sinus Sabaeus region of Mars. The light-toned rock is not really white, but its light tone caught the eye of Mars geologists as far back as 1972, when it was first spotted in images acquired by Mariner 9. The light-toned materials are probably the remains of a suite of layered sediments that once spread completely across the interior of Pollack Crater. Dark materials in this image include sand dunes and large ripples. Location near: 8.1oS, 335.1oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Summer

  2. Cenozoic basin thermal history reconstruction and petroleum systems in the eastern Colombian Andes (United States)

    Parra, Mauricio; Mora, Andres; Ketcham, Richard A.; Stockli, Daniel F.; Almendral, Ariel


    Late Mesozoic-Cenozoic retro-arc foreland basins along the eastern margin of the Andes in South America host the world's best detrital record for the study of subduction orogenesis. There, the world's most prolific petroleum system occur in the northernmost of these foreland basin systems, in Ecuador, Colombia and Venezuela, yet over 90% of the discovered hydrocarbons there occur in one single province in norteastern Venezuela. A successful industry-academy collaboration applied a multidisciplinary approach to the study of the north Andes with the aim of investigating both, the driving mechanisms of orogenesis, and its impact on hydrocarbon accumulation in eastern Colombia. The Eastern Cordillera is an inversion orogen located at the leading edge of the northern Andes. Syn-rift subsidence favored the accumulation of km-thick organic matter rich shales in a back-arc basin in the early Cretaceous. Subsequent late Cretaceous thermal subsidence prompted the accumulation of shallow marine sandstones and shales, the latter including the Turonian-Cenomanian main hydrocarbon source-rock. Early Andean uplift since the Paleocene led to development of a flexural basin, filled with mainly non-marine strata. We have studied the Meso-Cenozoic thermal evolution of these basins through modeling of a large thermochronometric database including hundreds of apatite and zircon fission-track and (U-Th)/He data, as well as paleothermometric information based on vitrinite reflectance and present-day temperatures measured in boreholes. The detrital record of Andean construction was also investigated through detrital zircon U-Pb geochronometry in outcrop and borehole samples. A comprehensive burial/exhumation history has been accomplished through three main modeling strategies. First, one-dimensional subsidence was used to invert the pre-extensional lithospheric thicknesses, the magnitude of stretching, and the resulting heat flow associated to extension. The amount of eroded section and

  3. Kinetics and reversibility of radionuclide sorption reactions with rocks. Progress report for fiscal year 1978

    International Nuclear Information System (INIS)

    Barney, G.S.; Anderson, P.D.


    Sorption reactions of environmentally significant radionuclides with rocks from proposed waste repository sites were examined. The kinetics and reversibility of sorption were studied by measuring the distribution of radioactive tracers between synthetic groundwaters and crushed basalt, granite, and argillite in batch experiments. The initial rapid sorption reaction is followed by a slow reaction which results from changes in the composition of the rock surface and bulk solution. Equilibrium concentrations of radionuclides were not reached even after 91 days. Dissolution of some rock components is also incomplete after this time. A relatively large amount of silica is dissolved in groundwaters contacted with basalt due to dissolution of the glassy phase of the basalt sample. This silica appears to increase the solubility of plutonium and americium. Artificially weathering basalt greatly increases the sorption capacity for each of the radionuclides studied. Weathering of granite had no observable effect on sorption. However, weathered argillite sorbs cesium, plutonium, and americium more strongly than unweathered argillite. Several irreversible sorption reactions were identified. Cesium is irreversibly sorbed on granite and ruthenium is irreversibly sorbed on basalt, granite, and argillite. Strontium and neptunium sorption are reversible for each rock type

  4. Mesozoic-Cenozoic tectonic evolution and its relation to sandstone-type uranium mineralization in northern Tarim area--Evidence from apatite fission track

    International Nuclear Information System (INIS)

    Liu Hongxu; Dong Wenming; Liu Zhangyue; Chen Xiaolin


    The apatite fission track dating and inversion result of geological thermal history of four rock specimens from Sawafuqi area and Talike area in northern Tarim Basin show that two areas uplifted at different ages. The apatite fission track ages of Sawafuqi range from 3.5 to 3.9 Ma, while the ages of Talike range from 53 to 59 Ma. The thermal history recorded by rock samples reveals that there are at least three prominent cooling phases since Late Cretaceous epoch. Detailed study was made on the division of uplifting stages during Mesozoic and Cenozoic tectonic evolution with the existing data in northern Tarim area. And new ideas on tectonic evolution and sandstone-type uranium mineralization have been put forward by combining with the sandstone-type uranium mineralization ages in this area.(authors)

  5. Experimental shock metamorphism of terrestrial basalts: Agglutinate-like particle formation, petrology, and magnetism (United States)

    Badyukov, Dmitrii D.; Bezaeva, Natalia S.; Rochette, Pierre; Gattacceca, Jérôme; Feinberg, Joshua M.; Kars, Myriam; Egli, Ramon; Raitala, Jouko; Kuzina, Dilyara M.


    Hypervelocity impacts occur on bodies throughout our solar system, and play an important role in altering the mineralogy, texture, and magnetic properties in target rocks at nanometer to planetary scales. Here we present the results of hypervelocity impact experiments conducted using a two-stage light-gas gun with 5 mm spherical copper projectiles accelerated toward basalt targets with 6 km s-1 impact velocities. Four different types of magnetite- and titanomagnetite-bearing basalts were used as targets for seven independent experiments. These laboratory impacts resulted in the formation of agglutinate-like particles similar in texture to lunar agglutinates, which are an important fraction of lunar soil. Materials recovered from the impacts were examined using a suite of complementary techniques, including optical and scanning electron microscopy, micro-Raman spectroscopy, and high- and low-temperature magnetometry, to investigate the texture, chemistry, and magnetic properties of newly formed agglutinate-like particles and were compared to unshocked basaltic parent materials. The use of Cu-projectiles, rather than Fe- and Ni-projectiles, avoids magnetic contamination in the final shock products and enables a clearer view of the magnetic properties of impact-generated agglutinates. Agglutinate-like particles show shock features, such as melting and planar deformation features, and demonstrate shock-induced magnetic hardening (two- to seven-fold increases in the coercivity of remanence Bcr compared to the initial target materials) and decreases in low-field magnetic susceptibility and saturation magnetization.

  6. Cumulate xenoliths from St. Vincent, Lesser Antilles Island Arc: a window into upper crustal differentiation of mantle-derived basalts (United States)

    Tollan, P. M. E.; Bindeman, I.; Blundy, J. D.


    In order to shed light on upper crustal differentiation of mantle-derived basaltic magmas in a subduction zone setting, we have determined the mineral chemistry and oxygen and hydrogen isotope composition of individual cumulus minerals in plutonic blocks from St. Vincent, Lesser Antilles. Plutonic rock types display great variation in mineralogy, from olivine-gabbros to troctolites and hornblendites, with a corresponding variety of cumulate textures. Mineral compositions differ from those in erupted basaltic lavas from St. Vincent and in published high-pressure (4-10 kb) experimental run products of a St. Vincent high-Mg basalt in having higher An plagioclase coexisting with lower Fo olivine. The oxygen isotope compositions (δ18O) of cumulus olivine (4.89-5.18‰), plagioclase (5.84-6.28‰), clinopyroxene (5.17-5.47‰) and hornblende (5.48-5.61‰) and hydrogen isotope composition of hornblende (δD = -35.5 to -49.9‰) are all consistent with closed system magmatic differentiation of a mantle-derived basaltic melt. We employed a number of modelling exercises to constrain the origin of the chemical and isotopic compositions reported. δ18OOlivine is up to 0.2‰ higher than modelled values for closed system fractional crystallisation of a primary melt. We attribute this to isotopic disequilibria between cumulus minerals crystallising at different temperatures, with equilibration retarded by slow oxygen diffusion in olivine during prolonged crustal storage. We used melt inclusion and plagioclase compositions to determine parental magmatic water contents (water saturated, 4.6 ± 0.5 wt% H2O) and crystallisation pressures (173 ± 50 MPa). Applying these values to previously reported basaltic and basaltic andesite lava compositions, we can reproduce the cumulus plagioclase and olivine compositions and their associated trend. We conclude that differentiation of primitive hydrous basalts on St. Vincent involves crystallisation of olivine and Cr-rich spinel at depth

  7. REE and Isotopic Compositions of Lunar Basalts Demonstrate Partial Melting of Hybridized Mantle Sources after Cumulate Overturn is Required (United States)

    Dygert, N. J.; Liang, Y.


    Lunar basalts maintain an important record of the composition of the lunar interior. Much of our understanding of the Moon's early evolution comes from studying their petrogenesis. Recent experimental work has advanced our knowledge of major and trace element fractionation during lunar magma ocean (LMO) crystallization [e.g., 1-3], which produced heterogeneous basalt sources in the Moon's mantle. With the new experimental constraints, we can evaluate isotopic and trace element signatures in lunar basalts in unprecedented detail, refining inferences about the Moon's dynamic history. Two petrogenetic models are invoked to explain the compositions of the basalts. The assimilation model argues they formed as primitive melts of early LMO cumulates that assimilated late LMO cumulates as they migrated upward. The cumulate overturn model argues that dense LMO cumulates sank into the lunar interior, producing hybridized sources that melted to form the basalts. Here we compare predicted Ce/Yb and Hf and Nd isotopes of partial melts of LMO cumulates with measured compositions of lunar basalts to evaluate whether they could have formed by end-member petrogenetic models. LMO crystallization models suggest all LMO cumulates have chondrite normalized Ce/Yb 1.5; these could not have formed by assimilation of any LMO cumulate or residual liquid (or KREEP basalt, which has isotopically negative ɛNd and ɛHf). In contrast, basalt REE patterns and isotopes can easily be modeled assuming partial melting of hybridized mantle sources, indicating overturn may be required. A chemical requirement for overturn independently confirms that late LMO cumulates are sufficiently low in viscosity to sink into the lunar interior, as suggested by recent rock deformation experiments [4]. Overturned, low viscosity late LMO cumulates would be relatively stable around the core [5]. High Ce/Yb basalts require that overturned cumulates were mixed back into the overlying mantle by convection within a few

  8. Geochemical characterization of Parana Basin volcanic rocks: petrogenetic implications

    International Nuclear Information System (INIS)

    Marques, L.S.


    A detailed study of the geochemical characteristics of Parana Basin volcanic rocks is presented. The results are based on the analyses of major and trace elements of 158 samples. Ninety three of these volcanic samples belong to 8 flow sequences from Rio Grande do Sul and Santa Catarina States. The remaining sixty five samples are distributed over the entire basin. In order to study the influence of crustal contamination processes in changing chemical characteristics of the volcanic rocks, 47 samples representative of the crystalline basement of the southern and southeastern Parana Basin were also analysed. Several petrogenetic models were tested to explain the compocional variability of the volcanic rocks, in particular those of southern region. The results obtained sugest an assimilation-fractional crystallization process as viable to explain the differences of both the chemical characteristics and Sr isotope initial ratios observed in basic and intermediate rocks. A model involving melting processes of basic material, trapped at the base of the crust, with composition similar to low and high TiO 2 basalts appears to be a possibility to originate the Palmas and Chapeco acid melts, respectively. The study of ''uncontaminated'' or poorly contaminated low TiO 2 basic rocks from the southern, central and northern regions shows the existence of significant differences in the geochemical charactetistics according to their geographical occurrence. A similar geochemical diversity is also observed in high TiO 2 basalts and Chapeco volcanics. Differences in incompatible element ratios between low and high TiO 2 ''uncontaminated'' or poorly contaminated basalts suggest that they could have been produced by different degrees of melting in a garnet peridotite source. Geochemical and isotopic (Sr and Nd) data also support the view that basalts from northern and southern regions of Parana Basin originated from mantle source with different composition. (author) [pt

  9. Alteration of immature sedimentary rocks on Earth and Mars. Recording Aqueous and Surface-atmosphere Processes

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, Kenneth M. [Brown Univ., Providence, RI (United States); Mustard, John F. [Brown Univ., Providence, RI (United States); Salvatore, Mark R. [Arizona State Univ., Mesa, AZ (United States)


    The rock alteration and rind formation in analog environments like Antarctica may provide clues to rock alteration and therefore paleoclimates on Mars. Clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of Mars. Moreover, how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows. Here we characterize alteration in the chemically immature Carapace Sandstone from Antarctica, a terrestrial analog for martian sedimentary rocks. We employ a variety of measurements similar to those used on previous and current Mars missions. Laboratory techniques included bulk chemistry, powder X-ray diffraction (XRD), hyperspectral imaging and X-ray absorption spectroscopy. Through these methods we find that primary basaltic material in the Carapace Sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water–rock interaction. A thick orange rind is forming in current Antarctic conditions, superimposing this previous aqueous alteration signature. The rind exhibits a higher reflectance at visible-near infrared wavelengths than the rock interior, with an enhanced ferric absorption edge likely due to an increase in Fe3+ of existing phases or the formation of minor iron (oxy)hydroxides. This alteration sequence in the Carapace Sandstone results from decreased water–rock interaction over time, and weathering in a cold, dry environment, mimicking a similar transition early in martian history. This transition may be recorded in sedimentary rocks on Mars through a similar superimposition mechanism, capturing past climate changes at the hand sample scale. These results also suggest that basalt-derived sediments could have sourced significant volumes of hydrated minerals on early Mars due to their greater permeability compared with intact igneous rocks.

  10. Bulk Chemical Fractionation Between Basalt, Impact-Melts and Spherules of Lonar Impact Crater, India (United States)

    Misra, S.; Prasad, M.; Saha, D.; Sengupta, D.; Khedekar, V. D.; Dube, A.; Newsom, H. E.


    The ~50,000 year old Lonar Crater, India, is one of the two known continental impact craters that were excavated on basalt. In-situ impact-melts from within ejecta from the SE crater rim are associated with splash form impact-spherules of two types: mm-size non-magnetic spherules, also found in other parts of the ejecta, and slightly smaller magnetic spherules with smoother surfaces. Both impact-melts and the two types of spherules have homogeneous compositions, though minor systematic variations exist in impact melts. Compared to unaltered target basalt, average impact-melt characteristically shows ~21-22% depletion in Na2O and ~44-61% enrichment in K2O, while impact-spherules show more depletion in Na2O (~41-42%) and less enrichment in K2O (~21-29%). Additionally average magnetic spherules are enriched in MgO (~22%) and depleted in CaO (~9%) and Fe2O3}T (~7%), while non-magnetic spherules are depleted in MgO (~11%) and enriched in CaO (~13%) and Fe2O3T (~2%) over target-basalt. #Mg for impact-melts and non-magnetic spherules have restricted and overlapping values between ~0.35 and 0.43, but for magnetic spherules it varies between 0.38 and 0.56. The small variation in mobile CaO (~3.4 wt%), Na2O (~2.4 wt%) and K2O (~0.8 wt%) of target-rock and impactites suggest limited weathering of the samples. Lonar impactites were formed by plagioclase- dominated partial melting of target-basalt, which caused enrichment of K2O in impactites and Rb, Cs, Ba, La, Ce, Nd and Th in impact-melts and non-magnetic spherules, while another important target- rock constituent, augite, was variably mixed with plagioclase-melt only in the highest stage of shock metamorphism. Depletion of Na2O in impactites occurred due to limited separation of xenocrystic augite (Na2O ~0.23 and 0.26 wt%) from these molten impactites. Mixing models suggest proportions of plagioclase melt and augite in average impact-melts and non-magnetic spherules is close to ~1:0.4, in magnetic spherules it varies

  11. A new method of discriminating different types of post-Archean ophiolitic basalts and their tectonic significance using Th-Nb and Ce-Dy-Yb systematics

    Directory of Open Access Journals (Sweden)

    Emilio Saccani


    Full Text Available In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to post-Archean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram was obtained using >2000 known ophiolitic basalts and was tested using ∼560 modern rocks from known tectonic settings. Ten different basaltic varieties from worldwide ophiolitic complexes have been examined. They include two basaltic types that have never been considered before, which are: (1 medium-Ti basalts (MTB generated at nascent forearc settings; (2 a type of mid-ocean ridge basalts showing garnet signature (G-MORB that characterizes Alpine-type (i.e., non volcanic rifted margins and ocean-continent transition zones (OCTZ. In the Th-Nb diagram, basalts generated in oceanic subduction-unrelated settings, rifted margins, and OCTZ can be distinguished from subduction-related basalts with a misclassification rate <1%. This diagram highlights the chemical variation of oceanic, rifted margin, and OCTZ basalts from depleted compositions to progressively more enriched compositions reflecting, in turn, the variance of source composition and degree of melting within the MORB-OIB array. It also highlights the chemical contributions of enriched (OIB-type components to mantle sources. Enrichment of Th relative to Nb is particularly effective for highlighting crustal input via subduction or crustal contamination. Basalts formed at continental margin arcs and island arc with a complex polygenetic crust can be distinguished from those generated in intra-oceanic arcs in supra-subduction zones (SSZ with a misclassification rate <1%. Within the SSZ group, two sub-settings can be recognized with a misclassification rate <0.5%. They are: (1 SSZ influenced by chemical contribution from subduction-derived components (forearc and intra-arc sub-settings characterized by island arc tholeiitic (IAT and boninitic basalts; (2 SSZ with no contribution from subduction

  12. Interaction of groundwater and fresh basalt fissure surfaces and its effect on the migration of actinides

    International Nuclear Information System (INIS)

    Vandegrift, G.F.; Bowers, D.L.; Gerding, T.J.; Fried, S.M.; Wilbur, C.K.; Seitz, M.G.


    Experiments are being performed at Argonne National Laboratory (ANL): (1) to identify interactions of radionuclides and repository components that effect nuclide migration, and (2) to assess changes in nuclide migration caused by modifications expected upon aging of the waste, clay backfill, and rock. The experiments are conducted with radioactive borosilicate glass, bentonite and mechanically fissured basalt rock in flowing water analogous to their configuration in a breach of a nuclear waste repository. Changes undergone by the groundwater as it passed through the fissure include: (1) drop in pH from 10 to 8, (2) loss of suspended particulate, and (3) loss of dissolved/suspended U, Np, and Pu. These effects, also studied as functions of radiation dose and of laboratory aging of the repository components, are related to the predicted long-term performance of a nuclear waste repository

  13. Spectral Variability among Rocks in Visible and Near Infrared Multispectral Pancam Data Collected at Gusev Crater: Examinations using Spectral Mixture Analysis and Related Techniques (United States)

    Farrand, W. H.; Bell, J. F., III; Johnson, J. R.; Squyres, S. W.; Soderblom, J.; Ming, D. W.


    Visible and Near Infrared (VNIR) multispectral observations of rocks made by the Mars Exploration Rover Spirit s Panoramic camera (Pancam) have been analysed using a spectral mixture analysis (SMA) methodology. Scenes have been examined from the Gusev crater plains into the Columbia Hills. Most scenes on the plains and in the Columbia Hills could be modeled as three endmember mixtures of a bright material, rock, and shade. Scenes of rocks disturbed by the rover s Rock Abrasion Tool (RAT) required additional endmembers. In the Columbia Hills there were a number of scenes in which additional rock endmembers were required. The SMA methodology identified relatively dust-free areas on undisturbed rock surfaces, as well as spectrally unique areas on RAT abraded rocks. Spectral parameters from these areas were examined and six spectral classes were identified. These classes are named after a type rock or area and are: Adirondack, Lower West Spur, Clovis, Wishstone, Peace, and Watchtower. These classes are discriminable based, primarily, on near-infrared (NIR) spectral parameters. Clovis and Watchtower class rocks appear more oxidized than Wishstone class rocks and Adirondack basalts based on their having higher 535 nm band depths. Comparison of the spectral parameters of these Gusev crater rocks to parameters of glass-dominated basaltic tuffs indicates correspondence between measurements of Clovis and Watchtower classes, but divergence for the Wishstone class rocks which appear to have a higher fraction of crystalline ferrous iron bearing phases. Despite a high sulfur content, the rock Peace has NIR properties resembling plains basalts.

  14. Uranium isotope composition of a laterite profile during extreme weathering of basalt in Guangdong, South China (United States)

    Huang, J.; Zhou, Z.; Gong, Y.; Lundstrom, C.; Huang, F.


    Rock weathering and soil formation in the critical zone are important for material cycle from the solid Earth to superficial system. Laterite is a major type of soil in South China forming at hot-humid climate, which has strong effect on the global uranium cycle. Uranium is closely related to the environmental redox condition because U is stable at U(Ⅳ) in anoxic condition and U(Ⅵ) as soluble uranyl ion (UO22+) under oxic circumstance. In order to understand the behavior of U isotopes during crust weathering, here we report uranium isotopic compositions of soil and base rock samples from a laterite profile originated from extreme weathering of basalt in Guangdong, South China. The uranium isotopic data were measured on a Nu Plasma MC-ICP-MS at the University of Illinois at Urbana-Champaign using the double spike method. The δ238U of BCR-1 is -0.29±0.03‰ (relative to the international standard CRM-112A), corresponding to a 238U/235U ratio of 137.911±0.004. Our result of BCR-1 agrees with previous analyses (e.g., -0.28‰ in Weyer et al. 2008) [1]. U contents of the laterite profile decrease from 1.9 ppm to 0.9 ppm with depth, and peak at 160 - 170 cm (2.3 ppm), much higher than the U content of base rocks (~0.5 ppm). In contrary, U/Th of laterites is lower than that of base rock (0.27) except the peak at the depth of 160-170 cm (0.38), indicating significant U loss during weathering. Notably, U isotope compositions of soils show a small variation from -0.38 to -0.28‰, consistent with the base rock within analytical error (0.05‰ to 0.08‰, 2sd). Such small variation can be explained by a "rind effect" (Wang et al., 2015) [2], by which U(Ⅳ) can be completely oxidized to U(VI) layer by layer during basalt weathering by dissolved oxygen. Therefore, our study indicates that U loss during basalt weathering at the hot-humid climate does not change U isotope composition of superficial water system. [1] Weyer S. et al. (2008) Natural fractionation of 238U/235

  15. Radiolarians decreased silicification as an evolutionary response to reduced Cenozoic ocean silica availability. (United States)

    Lazarus, David B; Kotrc, Benjamin; Wulf, Gerwin; Schmidt, Daniela N


    It has been hypothesized that increased water column stratification has been an abiotic "universal driver" affecting average cell size in Cenozoic marine plankton. Gradually decreasing Cenozoic radiolarian shell weight, by contrast, suggests that competition for dissolved silica, a shared nutrient, resulted in biologic coevolution between radiolaria and marine diatoms, which expanded dramatically in the Cenozoic. We present data on the 2 components of shell weight change--size and silicification--of Cenozoic radiolarians. In low latitudes, increasing Cenozoic export of silica to deep waters by diatoms and decreasing nutrient upwelling from increased water column stratification have created modern silica-poor surface waters. Here, radiolarian silicification decreases significantly (r = 0.91, P stratification and abundance of diatoms. In high southern latitudes, Southern Ocean circulation, present since the late Eocene, maintains significant surface water silica availability. Here, radiolarian silicification decreased insignificantly (r = 0.58, P = 0.1), from approximately 0.13 at 35 Ma to 0.11 today. Trends in shell size in both time series are statistically insignificant and are not correlated with each other. We conclude that there is no universal driver changing cell size in Cenozoic marine plankton. Furthermore, biologic and physical factors have, in concert, by reducing silica availability in surface waters, forced macroevolutionary changes in Cenozoic low-latitude radiolarians.

  16. An experimental investigation of high-temperature interactions between seawater and rhyolite, andesite, basalt and peridotite (United States)

    Hajash, Andrew; Chandler, Gary W.


    Natural seawater was allowed to react with rhyolite, andesite, basalt, and peridotite at 200° 500° C, and 1,000 bars at water/rock mass ratios of 5 and 50 in order to investigate the effects of rock type, water/rock ratio, and temperature on solution chemistry and alteration mineralogy. The results indicate that interactions of seawater with various igneous rocks are similar in the production of a hydrous Mg-silicate and anhydrite as major alteration products. Fluids involved in the interactions lose Mg to alteration phases while leaching Fe, Mn, and Si from the rocks. The pH of the solutions is primarily controlled by Mg-OH-silicate formation and therefore varies with Mg and Si concentration of the system. Other reactions which involve Mg (such as Mg-Ca exchange) or which produce free H+, cause major differences in fluid chemistry between different seawater/ rock systems. High water/rock ratio systems (50/1) are generally more acidic and more efficient in leaching than low ratio systems (5/1), due to relatively more seawater Mg available for Mgsilicate production. The experiments show that large-scale seawater/rock interaction could exert considerable control on the chemistry of seawater, as well as producing large bodies of altered rock with associated ore-deposits. Active plate margins of convergence or divergence are suitable environments for hydrothermal systems due to the concurrence of igneous activity, tectonism, and a nearby water reservoir (seawater or connate water). The experimental data indicate that seawater interactions with igneous host rocks could generate many of the features of ore-deposits such as the Kuroko deposits of Japan, the Raul Mine of Peru, the Bleida deposit of Morocco, and deposits associated with ophiolites. Serpentinization of peridotite and alteration of igneous complexes associated with plate margins can also be explained by seawater interaction with the cooling rock. Geothermal energy production could benefit from experimental

  17. New Insights to the Mid Miocene Calc-alkaline Lavas of the Strawberry Volcanics, NE Oregon Surrounded by the Coeval Tholeiitic Columbia River Basalt Province (United States)

    Steiner, A. R.; Streck, M. J.


    The Strawberry Volcanics (SV) of NE Oregon were distributed over 3,400 km2 during the mid-Miocene and comprise a diverse volcanic suite, which span the range of compositions from basalt to rhyolite. The predominant composition of this volcanic suite is calc-alkaline (CA) basaltic andesite and andesite, although tholeiitic (TH) lavas of basalt to andesite occur as well. The coeval flood basalts of the Columbia River province surround the SV. Here we will discuss new ages and geochemical data, and present a new geologic map and stratigraphy of the SV. The SV are emplaced on top of pre-Tertiary accreted terranes of the Blue Mountain Province, Mesozoic plutonic rocks, and older Tertiary volcanic rocks thought to be mostly Oligocene of age. Massive rhyolites (~300 m thick) are exposed mainly along the western flank and underlie the intermediate composition lavas. In the southern portion of this study area, alkali basaltic lavas, thought to be late Miocene to early Pliocene in age, erupted and overlie the SV. In addition, several regional ignimbrites reach into the area. The 9.7 Ma Devine Canyon Tuff and the 7.1 Ma Rattlesnake Tuff also overlie the SV. The 15.9-15.4 Ma Dinner Creek Tuff is mid-Miocene, and clear stratigraphic relationships are found in areas where the tuff is intercalated between thick SV lava flows. All of the basalts of the SV are TH and are dominated by phenocryst-poor (≤2%) lithologies. These basalts have an ophitic texture dominated by plagioclase, clinopyroxene and olivine (often weathered to iddingsite). Basalts and basaltic andesites have olivine Fo #'s ranging from 44 at the rims (where weathered to iddingsite) and as high as 88 at cores. Pyroxene Mg #'s range from 65 to 85. Andesites of the SV are sub-alkaline, and like the basalts, are exceedingly phenocryst-poor (≤3%) with microphenocrysts of plagioclase and lesser pyroxene and olivine, which occasionally occur as crystal clots of ~1-3 mm instead of single crystals. In addition, minimal

  18. Thermal Inertia of Rocks and Rock Populations (United States)

    Golombek, M. P.; Jakosky, B. M.; Mellon, M. T.


    The effective thermal inertia of rock populations on Mars and Earth is derived from a model of effective inertia versus rock diameter. Results allow a parameterization of the effective rock inertia versus rock abundance and bulk and fine component inertia. Additional information is contained in the original extended abstract.


    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich


    Full Text Available The authors demonstrate that the foam concrete performance can be improved by dispersed reinforcement, including methods that involve basalt fibres. They address the results of the foam concrete modeling technology and assess the importance of technology-related parameters. Reinforcement efficiency criteria are also provided in the article. Dispersed reinforcement improves the plasticity of the concrete mix and reduces the settlement crack formation rate. Conventional reinforcement that involves metal laths and rods demonstrates its limited application in the production of concrete used for thermal insulation and structural purposes. Dispersed reinforcement is preferable. This technology contemplates the infusion of fibres into porous mixes. Metal, polymeric, basalt and glass fibres are used as reinforcing components. It has been identified that products reinforced by polypropylene fibres demonstrate substantial abradability and deformability rates even under the influence of minor tensile stresses due to the low adhesion strength of polypropylene in the cement matrix. The objective of the research was to develop the type of polypropylene of D500 grade that would demonstrate the operating properties similar to those of Hebel and Ytong polypropylenes. Dispersed reinforcement was performed by the basalt fibre. This project contemplates an autoclave-free technology to optimize the consumption of electricity. Dispersed reinforcement is aimed at the reduction of the block settlement in the course of hardening at early stages of their operation, the improvement of their strength and other operating properties. Reduction in the humidity rate of the mix is based on the plasticizing properties of fibres, as well as the application of the dry mineralization method. Selection of optimal parameters of the process-related technology was performed with the help of G-BAT-2011 Software, developed at Moscow State University of Civil Engineering. The authors also

  20. Mineralogy and geochemistry of picro-dolerite dykes from the central Deccan Traps flood basaltic province, India, and their geodynamic significance (United States)

    Dongre, Ashish; Viljoen, K. S.; Rathod, A.


    Constituent mineral compositions and whole rock major element geochemistry of picro-dolerite dykes from the central part of the Deccan flood basalt province are presented and discussed. The dykes are characterized by an MgO content of about 13 wt%, coupled with 13-16 modal percents of olivine. A high whole rock molar Mg# value of 71 and the presence of magnesian olivine phenocrysts ( Fo78) are consistent with a primitive (i.e. unevolved) geochemistry. The nature and composition of clinopyroxene (augite and pigeonite), plagioclase feldspar (labradorite) and Fe-Ti oxides (mostly ilmenite and magnetite) are also discussed, with implications drawn with respect to the geodynamics. High MgO magmas and rocks such as picrites are generally considered to be indicative of plume magmatism, formed by high degrees of partial melting in, e.g. the high-temperature region of a plume head. Recent age data is consistent with a model in which the Deccan LIP picritic magmatism is associated with the main phase of Deccan Trap activity at 66 Ma, as a result of a syn- to post rifting phase associated with the impact of the Rèunion mantle plume. It is speculated that the differentiation of primary olivine basaltic magma of picritic composition, may have been the mechanism for the generation of alkalic basalts which occurs in the Deccan Trap basaltic sequence.

  1. Petrogenesis of the Jiaoziding granitoids and associated basaltic porphyries: Implications for extensive early Neoproterozoic arc magmatism in western Yangtze Block (United States)

    Li, Jun-Yong; Wang, Xiao-Lei; Gu, Zhi-Dong


    Middle Neoproterozoic (ca 860-750 Ma) granitoids are widely distributed in the western margin of the Yangtze Block, China, yet their magma sources and tectonic settings are unclear. The geochronology and geochemistry of the granitoids and associated basaltic porphyries, which intruded the 970 Ma Tongmuliang arc volcanic rocks in the Jiaoziding area (east of Pingwu county), were investigated in this study. LA-ICP-MS zircon U-Pb dating indicates that the Jiaoziding granitoids and basaltic porphyries were formed at 795 ± 6 Ma and 790 ± 20 Ma, respectively. The granitoids have high SiO2 (69.2-76.9 wt%), K2O (2.3-5.6 wt%), and Na2O (3.2-5.1 wt%) contents, and a low Al2O3 (12.4-14.5 wt%) content. The basaltic porphyries contain high concentrations of TiO2 ( 3 wt%) and high field strength elements, have steep rare earth element patterns, and are depleted in Nd and Hf isotopes. Batch partial-melting modelling indicates that the Jiaoziding granitoids could have been derived by 5% and 50-70% partial melting of Tongmuliang mafic rocks and quartz-keratophyres, respectively. Formation of the basaltic porphyries by melting of upwelling asthenospheric mantle would have been facilitated by extensive lithospheric delamination during the Neoproterozoic. This study established a link between mid-Neoproterozoic granitic magmatism and 970 Ma juvenile arc crust, indicating that extensive early Neoproterozoic juvenile arc crust, and partial melting of this crust in an extensional setting, favoured the formation of middle Neoproterozoic granitic rocks along the W-NW margin of the Yangtze Block.

  2. The 13 million year Cenozoic pulse of the Earth (United States)

    Chen, Jiasheng; Kravchinsky, Vadim A.; Liu, Xiuming


    The geomagnetic polarity reversal rate changes radically from very low to extremely high. Such process indicates fundamental changes in the Earth's core reorganization and core-mantle boundary heat flow fluctuations. However, we still do not know how critical such changes are to surface geology and climate processes. Our analysis of the geomagnetic reversal frequency, oxygen isotope record, and tectonic plate subduction rate, which are indicators of the changes in the heat flux at the core mantle boundary, climate and plate tectonic activity, shows that all these changes indicate similar rhythms on million years' timescale in the Cenozoic Era occurring with the common fundamental periodicity of ∼13 Myr during most of the time. The periodicity is disrupted only during the last 20 Myr. Such periodic behavior suggests that large scale climate and tectonic changes at the Earth's surface are closely connected with the million year timescale cyclical reorganization of the Earth's interior.

  3. Multiple cenozoic invasions of Africa by penguins (Aves, Sphenisciformes) (United States)

    Ksepka, Daniel T.; Thomas, Daniel B.


    Africa hosts a single breeding species of penguin today, yet the fossil record indicates that a diverse array of now-extinct taxa once inhabited southern African coastlines. Here, we show that the African penguin fauna had a complex history involving multiple dispersals and extinctions. Phylogenetic analyses and biogeographic reconstructions incorporating new fossil material indicate that, contrary to previous hypotheses, the four Early Pliocene African penguin species do not represent an endemic radiation or direct ancestors of the living Spheniscus demersus (blackfooted penguin). A minimum of three dispersals to Africa, probably assisted by the eastward-flowing Antarctic Circumpolar and South Atlantic currents, occurred during the Late Cenozoic. As regional sea-level fall eliminated islands and reduced offshore breeding areas during the Pliocene, all but one penguin lineage ended in extinction, resulting in today's depleted fauna. PMID:21900330

  4. Cenozoic siliciclastic sediment budget at continent-scale, Africa. (United States)

    Guillocheau, François; Robin, Cécile; Calves, Gérôme; Baby, Guillaume


    Siliciclastic sediment budget measurements was performed along the margins and onshore basins of Africa for Cenozoic times. Our objective was first to quantify the ratio between onshore and offshore sediment preservation in the case of a relief with mostly no mountain belt and secondly to understand the factors forcing the sediment supply along the passive margins of Africa that can be long to very-long relief deformation (mantle dynamics, ridge push…) or climate changes (with the major aridification of Africa since Middle Miocene). This study is based on basin-scale regional sections (seismic reflection data from industry and academics, wells correlation), calibrated in age and lithology on different types of wells (industry, DSDP/ODP). Most of the effort was on the revaluation of the ages (calibration and uncertainties). The volumes of sediments and uncertainties on depth conversion velocity laws, lithology and ages were measured using software developed by J. Braun (Grenoble University, France). • The sediment preserved onshore (750 000 km3) is one of magnitude less than was is preserved offshore • The main deformations controlling the sediment supply are (1) the growth or the domes of the East African rift and (2) the marginal bulge of the central and equatorial segments of the South Atlantic Ocean (from southern Angola to Guinea). • The aridification of Africa since at least Middle Miocene is very sensitive in the south (fossilization of the relief of the South African Plateau) and in the northwest, with a sharp decrease of the sediment supply. • Some buffer effects are very important, for example for the Nile and the Zambezi, where sediments were first stored in onshore basins, Sudan or Malawi rift, and later drained because of a capture (Nile) or a regional stress change (Zambezi). Keywords: Africa, Cenozoic, Siliciclastic sediment fluxes, Deformation, Climate

  5. Plutonium speciation in selected basalt, granite, shale, and tuff ground waters

    International Nuclear Information System (INIS)

    Cleveland, J.M.; Nash, K.L.; Rees, T.F.


    The speciation of added plutonium was determined in ground waters of widely varying composition from four rock types: basalt, granite, shale, and tuff. Plutonium was soluble in the basalt water, which contained a high fluoride ion concentration, probably as a result of its stabilization in solution as fluorocomplexes, primarily of plutonium (IV); it was insoluble, however, in the shale ground water, which contained the highest concentration of sulfate ion. Results were intermediate in the granite and tuff ground waters. In synthetic waters containing significant concentrations of both sulfate and fluoride, the effects were smaller and less predictable. Dissolved oxygen, ionic strength, carbonate ion concentration, and pH had little effect on plutonium speciation in the ranges encountered in this study. However, other ionic species not involved in this study may also influence plutonium speciation. The results have potential significance in establishing site-selection criteria for radioactive waste repositories. All other factors being equal, host rocks whose associated waters contain low concentrations of free fluoride ion should be preferable for the location of waste repositories

  6. Basalt Reactivity Variability with Reservoir Depth in Supercritical CO2 and Aqueous Phases

    Energy Technology Data Exchange (ETDEWEB)

    Schaef, Herbert T.; McGrail, B. Peter; Owen, Antionette T.


    Long term storage of CO{sub 2} in geologic formations is currently considered the most attractive option to reduce greenhouse gas emissions while continuing to utilize fossil fuels for energy production. Injected CO{sub 2} is expected to reside as a buoyant water-saturated supercritical fluid in contact with reservoir rock, the caprock system, and related formation waters. As was reported for the first time at the GHGT-9 conference, experiments with basalts demonstrated surprisingly rapid carbonate mineral formation occurring with samples suspended in the scCO{sub 2} phase. Those experiments were limited to a few temperatures and CO{sub 2} pressures representing relatively shallow (1 km) reservoir depths. Because continental flood basalts can extend to depths of 5 km or more, in this paper we extend the earlier results across a pressure-temperature range representative of these greater depths. Different basalt samples, including well cuttings from the borehole used in a pilot-scale basalt sequestration project (Eastern Washington, U.S.) and core samples from the Central Atlantic Magmatic Province (CAMP), were exposed to aqueous solutions in equilibrium with scCO{sub 2} and water-rich scCO{sub 2} at six different pressures and temperatures for select periods of time (30 to 180 days). Conditions corresponding to a shallow injection of CO{sub 2} (7.4 MPa, 34 C) indicate limited reactivity with basalt; surface carbonate precipitates were not easily identified on post-reacted basalt grains. Basalts exposed under identical times appeared increasingly more reacted with simulated depths. Tests, conducted at higher pressures (12.0 MPa) and temperatures (55 C), reveal a wide variety of surface precipitates forming in both fluid phases. Under shallow conditions tiny clusters of aragonite needles began forming in the wet scCO{sub 2} fluid, whereas in the CO{sub 2} saturated water, cation substituted calcite developed thin radiating coatings. Although these types of coatings

  7. Cenozoic geology of the Yolomécatl-Tlaxiaco area, Northwestern Oaxaca, Southeastern Mexico: Stratigraphy, structure and regional significance (United States)

    Ferrusquía-Villafranca, Ismael; Ruiz-González, José E.; Torres-Hernández, José Ramón; Anderson, Thomas H.; Urrutia-Fucugauchi, Jaime; Martínez-Hernández, Enrique; García-Villegas, Felipe


    The Yolomécatl-Tlaxiaco Area, lies in the rugged Sierra Madre del Sur (SMS) of northwestern Oaxaca (YOTLA), southeastern Mexico. Within the area Cenozoic units unconformably overlie metamorphic, clastic and carbonate rock units of Late Paleozoic to Cretaceous ages as well as the Mixteco/Oaxaca Terrane boundary. The Cenozoic sequence, emphasized herein, includes from botton to top: (1) basal, calcilithitic Early Tertiary Tamazulapam Conglomerate, (2) andesitic lava flows of Nduayaco "Group," (3-4) Epiclastic/pyroclastic strata composing Yolomécatl Formation (∼40.3 ± 1.0 Ma), and Tayata Pyroepiclastics (5) Early Oligocene (∼32.9 Ma), felsic, pyroclastic Nundichi "Group," (6) Late Oligocene (∼27.7 ± 0.7 Ma) andesitic lava flows of Nicananduta "Group" containing intercalations of unit (7) ?Chilapa Formation (largely lacustrine). Quaternary deposits unconformably overlie the sequence. The structural record includes NNW-SSE folds in the Mesozoic units, and one in Tayata Pyroepiclastics, as well as numerous fractures/faults of diverse types, whose pattern seems to roughly define four geographic/structural domains, NW, SW, S, and E. The Tertiary sequence records four magmatic and six deformational events: Pre-Late Eocene Extension accommodated by the Tamazulapam fault, along which magma of the Nduayaco "Group" moved upward. The next episode is the earliest Late Eocene extension recorded by the Yucuxaco-Santa Cruz Tayata fault was followed by accumulation of Yolomécatl Formation, Tayata Pyroepiclastics, and synsedimentary emplacement of tuff sheets at ∼40.3 ± 1.0 Ma. After this date, left lateral transpression emplaced a Teposcolula Limestone block over Nduayaco "Group" and ?Yolomécatl Formation, whereas the Tayata Pyroepiclastics was folded into an open anticline. Movement along the Yucuxaco-Santa Cruz Tayayata fault suite influenced accumulation of the Nundichi "Group" strata ca. ∼32.9 Ma. Subsequent ENE-WSW extension affected the Nundichi "Group," partly

  8. Basaltic substrate composition affects microbial community development and acts as a source of nutrients in the deep biosphere (United States)

    Bailey, B.; Sudek, L.; Templeton, A.; Staudigel, H.; Tebo, B.; Moyer, C.; Davis, R.


    Studies of the oceanic crust over the past decade have revealed that in spite of the oligotrophic nature of this environment, a diverse biosphere is present in the upper 1 km of basaltic crust. The key energy source in this setting may be the high content of transistion metals (Fe, Mn) found in the basaltic glass, but in order to discover the role of Fe and Mn in the deep biosphere, we must first determine which microbes are present and how they attain the necessary metabolites for proliferation. Our work contributes to both questions through the use of molecular microbiology techniques and the exposure of specifically designed substrates on the ocean floor. Loihi Seamount off the southeast coast of the Big Island of Hawai'i provides a unique laboratory for the study of distribution and population of microbial communities associated with iron rich environments on the ocean floor. Iron oxide flocculent material (floc) dominates the direct and diffuse hydrothermal venting areas on Loihi which makes it a prime target for understanding the role of iron in biological systems in the deep biosphere. We collected iron oxide floc and basaltic glass from pillow basalts around several hydrothermal vents on the crater rim, within the pit crater Pele's Pit, and from deep off of the southern rift zone of Loihi using the HURL PISCES IV/V submersibles. We also deployed basaltic glass sand amended with various nutrients (phosphate, oxidized and reduced iron, manganese) and recovered them in subsequent years to determine how substrate composition affects community structure. We extracted DNA from both rock and iron flocs and used t-RFLP to obtain a genetic fingerprint of the microbial communities associated with each substrate. From olivine and tholeiitic basalt enrichments, it appears that substrate composition strongly influences microbial colonization and subsequent community development even when deployed in the same conditions. Culturing efforts have yielded several iron

  9. Mesozoic and Cenozoic uplift and exhumation of the Bogda Mountain, NW China: Evidence from apatite fission track analysis

    Directory of Open Access Journals (Sweden)

    Wenhao Tang


    Full Text Available Apatite fission track (AFT analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0–13.2 μm mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassic–early Cretaceous and the Oligocene–Miocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma, recording the earlier rapid uplift phase during the late Jurassic–Cretaceous, while the ages in the north piedmont of the Bogda Mountain (namely the northeast part are younger (<60 Ma, mainly reflecting the later rapid uplift phase in the Oligocene–Miocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

  10. Crystal Stratigraphy of Two Basalts from Apollo 16: Unique Crystallization of Picritic Basalt 606063,10-16 and Very-Low-Titanium Basalt 65703,9-13 (United States)

    Donohue, P. H.; Neal, C. R.; Stevens, R. E.; Zeigler, R. A.


    A geochemical survey of Apollo 16 regolith fragments found five basaltic samples from among hundreds of 2-4 mm regolith fragments of the Apollo 16 site. These included a high-Ti vitrophyric basalt (60603,10-16) and one very-low-titanium (VLT) crystalline basalt (65703,9-13). Apollo 16 was the only highlands sample return mission distant from the maria (approx. 200 km). Identification of basaltic samples at the site not from the ancient regolith breccia indicates input of material via lateral transport by post-basin impacts. The presence of basaltic rocklets and glass at the site is not unprecedented and is required to satisfy mass-balance constraints of regolith compositions. However, preliminary characterization of olivine and plagioclase crystal size distributions indicated the sample textures were distinct from other known mare basalts, and instead had affinities to impact melt textures. Impact melt textures can appear qualitatively similar to pristine basalts, and quantitative analysis is required to distinguish between the two in thin section. The crystal stratigraphy method is a powerful tool in studying of igneous systems, utilizing geochemical analyses across minerals and textural analyses of phases. In particular, trace element signatures can aid in determining the ultimate origin of these samples and variations document subtle changes occurring during their petrogenesis.

  11. Origin of CaCl2 brines by basalt-seawater interaction: Insights provided by some simple mass balance calculations (United States)

    Hardie, Lawrence A.


    Modern rift zone hydrothermal brines are typically CaCl2-bearing brines, an unusual chemical signature they share with certain oil field brines, fluid inclusions in ore minerals and a few uncommon saline lakes. Many origins have been suggested for such CaCl2 brines but in the Reykjanes, Iceland, geothermal system a strong empirical case can be made for a basalt-seawater interaction origin. To examine this mechanism of CaCl2 brine evolution some simple mass balance calculations were carried out. Average Reykjanes olivine tholeiite was “reacted” with average North Atlantic seawater to make an albite-chlorite-epidotesphene rock using Al2O3 as the conservative rock component and Cl as the conservative fluid component. The excess components released by the basalt to the fluid were “precipitated” at 275° C as quartz, calcite, anhydrite, magnetite and pyrite to complete the conversion to greenstone. The resulting fluid was a CaCl2 brine of seawater chlorinity with a composition remarkably similar to the actual Reykjanes brine at 1750 m depth. Thus, the calculations strongly support the idea that the Reykjanes CaCl2 brines result from “closed system” oceanic basalt-seawater interaction (albitization — chloritization mechanism) at greenschist facies temperatures. The calculation gives a seawater: basalt mass ratio of 3∶1 to 4∶1 (vol. ratio of 9∶1 to 12∶1), in keeping with experimental results, submarine vent data and with ocean crust cooling calculations. The brine becomes anoxic because there is insufficient dissolved or combined oxygen to balance all the Fe released from the basalt during alteration. Large excesses of Ca are released to the fluid and precipitate out in the form of anhydrite which essentially sweeps the brine free of sulfate leaving an elevated Ca concentration. The calculated rock-water interaction basically involves Na + Mg + SO4 ⇌ Ca + K, simulating chemical differences observed between oceanic basalts and greenstones from many

  12. Ambient noise tomography reveals basalt and sub-basalt velocity structure beneath the Faroe Islands, North Atlantic (United States)

    Sammarco, Carmelo; Cornwell, David G.; Rawlinson, Nicholas


    Ambient noise tomography is applied to seismic data recorded by a portable array of seismographs deployed throughout the Faroe Islands in an effort to illuminate basalt sequences of the North Atlantic Igneous Province, as well as underlying sedimentary layers and Precambrian basement. Rayleigh wave empirical Green's functions between all station pairs are extracted from the data via cross-correlation of long-term recordings, with phase weighted stacking implemented to boost signal-to-noise ratio. Dispersion analysis is applied to extract inter-station group travel-times in the period range 0.5-15 s, followed by inversion for period-dependent group velocity maps. Subsequent inversion for 3-D shear wave velocity reveals the presence of significant lateral heterogeneity (up to 25%) in the crust. Main features of the final model include: (i) a near-surface low velocity layer, interpreted to be the Malinstindur Formation, which comprises subaerial compound lava flows with a weathered upper surface; (ii) a sharp velocity increase at the base of the Malinstindur Formation, which may mark a transition to the underlying Beinisvørð Formation, a thick laterally extensive layer of subaerial basalt sheet lobes; (iii) a low velocity layer at 2.5-7.0 km depth beneath the Beinisvørð Formation, which is consistent with hyaloclastites of the Lopra Formation; (iv) an upper basement layer between depths of 5-9 km and characterized by S wave velocities of approximately 3.2 km/s, consistent with low-grade metamorphosed sedimentary rocks; (v) a high velocity basement, with S wave velocities in excess of 3.6 km/s. This likely reflects the presence of a crystalline mid-lower crust of Archaean continental origin. Compared to previous interpretations of the geological structure beneath the Faroe Islands, our new results point to a more structurally complex and laterally heterogeneous crust, and provide constraints which may help to understand how continental fragments are rifted from the

  13. Degassing of reduced carbon from planetary basalts. (United States)

    Wetzel, Diane T; Rutherford, Malcolm J; Jacobsen, Steven D; Hauri, Erik H; Saal, Alberto E


    Degassing of planetary interiors through surface volcanism plays an important role in the evolution of planetary bodies and atmospheres. On Earth, carbon dioxide and water are the primary volatile species in magmas. However, little is known about the speciation and degassing of carbon in magmas formed on other planets (i.e., Moon, Mars, Mercury), where the mantle oxidation state [oxygen fugacity (fO2)] is different from that of the Earth. Using experiments on a lunar basalt composition, we confirm that carbon dissolves as carbonate at an fO2 higher than -0.55 relative to the iron wustite oxygen buffer (IW-0.55), whereas at a lower fO2, we discover that carbon is present mainly as iron pentacarbonyl and in smaller amounts as methane in the melt. The transition of carbon speciation in mantle-derived melts at fO2 less than IW-0.55 is associated with a decrease in carbon solubility by a factor of 2. Thus, the fO2 controls carbon speciation and solubility in mantle-derived melts even more than previous data indicate, and the degassing of reduced carbon from Fe-rich basalts on planetary bodies would produce methane-bearing, CO-rich early atmospheres with a strong greenhouse potential.

  14. Determination of gamma ray shielding parameters of rocks and concrete (United States)

    Obaid, Shamsan S.; Gaikwad, Dhammajyot K.; Pawar, Pravina P.


    Gamma shielding parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Zeff) and electron density (Neff) have been measured and calculated for rocks and concrete in the energy range 122-1330 keV. The measurements have been carried out at 122, 356, 511, 662, 1170, 1275, 1330 keV gamma ray energies using a gamma spectrometer includes a NaI(Tl) scintillation detector and MCA card. The atomic and electronic cross sections have also been investigated. Experimental and calculated (WinXCom) values were compared, and good agreement has been observed within the experimental error. The obtained results showed that feldspathic basalt, compact basalt, volcanic rock, dolerite and pink granite are more efficient than the sandstone and concrete for gamma ray shielding applications.

  15. Post-collisional basalts of the Acampamento Velho Formation, Camaquã Basin, São Gabriel Terrane, southernmost Brazil

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    Luiz Alberto Vedana

    Full Text Available ABSTRACT: The basic volcanic rocks in the Palma region, southern portion of the São Gabriel Terrane, have always been interpreted as generated during the active subduction period of the São Gabriel orogeny (Cryogenian. This terrane was built as the result of the Charrua Ocean closure between 900-680 Ma. The basalts show a subhorizontal igneous flow foliation and porphyritic texture, with plagioclase phenocrysts in a thin matrix composed of plagioclase, augite and magnetite, commonly altered to actinolite, chlorite and epidote. They have amygdales and veinlets reflecting a pervasive hydrothermal phase and are affected by thermal metamorphism related to Jaguari granite intrusion. Two samples were dated by the U-Pb zircon geochronology and yielded crystallization ages of 563±2 Ma and 573±6 Ma. The basalts have transitional composition from tholeiitic to calc-alkaline, metaluminous character, trace elements patterns rich in large-ion lithophile element (LILE with negative anomalies of Nb, P and Ti, slight enrichment in light rare-earth elements (LREE and horizontal pattern of heavy rare earth elements (HREE. The data allow interpreting the basalts as belonging to the Acampamento Velho Formation of the Camaquã Basin, and related to the basalts of the Ramada and Taquarembó plateaus. These associations represent the final evolution of the volcanism generated in the post-collisional period of the Dom Feliciano Belt.


    Directory of Open Access Journals (Sweden)

    Sibila Borojević Šostarić


    Full Text Available Underground geological storage of high- and intermediate/low radioactive waste is aimed to represent a barrier between the surface environment and potentially hazardous radioactive elements. Permeability, behavior against external stresses, chemical reacatibility and absorption are the key geological parameters for the geological storage of radioactive waste. Three principal rock types were discussed and applied to the Dinarides: (1 evaporites in general, (2 shale, and (3 crystalline basement rocks. (1 Within the Dinarides, evaporite formations are located within the central part of a Carbonate platform and are inappropriate for storage. Offshore evaporites are located within diapiric structures of the central and southern part of the Adriatic Sea and are covered by thick Mesozoic to Cenozoic clastic sediment. Under very specific circumstances they can be considered as potential site locations for further investigation for the storage of low/intermediate level radioactive wast e. (2 Thick flysch type formation of shale to phyllite rocks are exposed at the basement units of the Petrova and Trgovska gora regions whereas (3 crystalline magmatic to metamorphic basement is exposed at the Moslavačka Gora and Slavonian Mts. regions. For high-level radioactive waste, basement phyllites and granites may represent the only realistic potential option in the NW Dinarides.

  17. [In Situ Analysis of Element Geochemistry in Submarine Basalt in Hydrothermal Areas from Ultraslow Spreading Southwest Indian Ridge]. (United States)

    Wang, Yan; Sun, Xiao-ming; Xu, Li; Liang, Ye-heng; Wu, Zhong-wei; Fu, Yu; Huang, Yi


    In this study, we analyze element geochemistry of submarine basalt in situ, which is sampled in hydrothermal areas from ultraslow spreading Southwest Indian Ridge, including the fresh basalt rocks (B19-9, B15-13) and altered basalt (B5-2). And we can confirm that altered mineral in B5-2 is celadonite by microscope and Raman Spectrum. Furthermore, amygdaloidal celadonites are analyzed by electron microprobe (EPMA) and EDS-line scanning. The results show that K-contents decrease and Na-contents increase from the core to the edge in these altered minerals, indicating the transition from celadonite to saponite. Celadonite is an altered minerals, forming in low temperature (form in low water/rock and more reducing condition. As a result, the transition from celadonite to saponite suggests environment change from oxidizing to reducing condition. Using the result of EPMA as internal standard, we can analyze rare earth elements (REE) in altered mineral in situ. Most of result show positive Eu anomaly (Δ(Eu)), indicating hydrothermal fluid transform from oxidizing to reducing, and reducing fluid rework on the early altered minerals. Comparison with REE in matrix feldspar both in altered and unaltered zoning, we find that reducing fluid can leach REE from the matrix feldspar, leading to lower total REE concentrations and positive Eu anomaly. So leaching process play an important role in hydrothermal system.

  18. Constructibility issues associated with a nuclear waste repository in basalt

    International Nuclear Information System (INIS)

    Turner, D.A.


    This report contains the text and slide reproductions of a speech on nuclear waste disposal in basalt. The presentation addresses the layout of repository access shafts and subsurface facilities resulting from the conceptual design of a nuclear repository in basalt. The constructibility issues that must be resolved prior to construction are described

  19. Hydrogeology of the basalts in the Uruguayan NW

    International Nuclear Information System (INIS)

    Hausman, A.; Fernandez, A.


    This work is about the hydrogeological aspects in the NW Uruguayan basaltic area. The results of this research are the main geological, morphological and hydrogeological aspects of the area as well as the characteristics and the color of the basalt and sandstones

  20. A note on incipient spilitisation of central Indian basin basalts

    Digital Repository Service at National Institute of Oceanography (India)

    Karisiddaiah, S.M.; Iyer, S.D.

    of chlorite, epidote and opaques. The oxide variation plots indicate a mid-ocean ridge basalt trend for the samples, which have been spilitised to varying degrees. It is suggested that the basalts formed as a result of a fissure type of eruption along...

  1. Use of basaltic waste as red ceramic raw material

    Directory of Open Access Journals (Sweden)

    T. M. Mendes

    Full Text Available Abstract Nowadays, environmental codes restrict the emission of particulate matters, which result in these residues being collected by plant filters. This basaltic waste came from construction aggregate plants located in the Metropolitan Region of Londrina (State of Paraná, Brazil. Initially, the basaltic waste was submitted to sieving (< 75 μm and the powder obtained was characterized in terms of density and particle size distribution. The plasticity of ceramic mass containing 0%, 10%, 20%, 30%, 40% and 50% of basaltic waste was measured by Atterberg method. The chemical composition of ceramic formulations containing 0% and 20% of basaltic waste was determined by X-ray fluorescence. The prismatic samples were molded by extrusion and fired at 850 °C. The specimens were also tested to determine density, water absorption, drying and firing shrinkages, flexural strength, and Young's modulus. Microstructure evaluation was conducted by scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. Basaltic powder has similar physical and chemical characteristics when compared to other raw materials, and contributes to ceramic processing by reducing drying and firing shrinkage. Mechanical performance of mixtures containing basaltic powder is equivalent to mixtures without waste. Microstructural aspects such as pore size distribution were modified by basaltic powder; albite phase related to basaltic powder was identified by X-ray diffraction.

  2. Mineral chemistry of Pangidi basalt flows from Andhra Pradesh

    Indian Academy of Sciences (India)

    Pangidi basalts follow the QFM buffer curve which indicates the more evolved tholeiitic composition. This suggests the parent tholeiitic magma suffered limited fractionation at high temperature under increasing oxygen fugacity in lower basalt flow and more fractionation at medium to lower temperatures under decreasing ...

  3. Basalt Weathering and the Volatile Budget of Early Mars (United States)

    Baker, L. L.


    Basalt weathering on Earth consumes CO2 and water and may have affected terrestrial climate. I apply a mass balance derived from terrestrial data to examine the effect surficial basalt weathering may have had on the CO2 budget of early Mars.

  4. Petrology of offshore basalts of Bombay harbour area, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Karisiddaiah, S.M.

    glass are conspicuous. The chemical data indicate that the basalts are tholeiitic. Secondary minerals encountered support the view that the basalts are spilitised. Basalts of this area show affinities to both continental and oceanic types especially...

  5. Like a cannonball: origin of dense spherical basaltic ejecta (United States)

    Di Piazza, Andrea; Del Bello, Elisabetta; Mollo, Silvio; Vona, Alessandro; Alvarado, Guillermo E.; Masotta, Matteo


    Cannonballs are rare spherical to sub-spherical eruptive products associated with basaltic explosive activity. The origin of cannonballs is still debated and subjected to a wide spectrum of different interpretations. In order to better understand the physicochemical mechanisms controlling the formation of these explosive products, we investigated the textural and chemical features of cannonballs from the Cerro Chopo monogenetic volcano (Costa Rica). These explosive products ubiquitously show a core domain with coalesced bubbles (30-36% porosity) wrapped in a dense rim domain with small, isolated bubbles (20-27% porosity). Both domains are identical in terms of bulk rock composition and mineral chemistry and are portions of the same magma batch. Results from combined petrological and thermodynamic modeling indicate that a low-viscosity ( 20 Pa s) melt containing early-formed olivine phenocrysts ( 9 vol.%) ascended from storage at a decompression rate of 0.5 MPa s-1 until it reached a depth of 4.5 km (equivalent to a pressure of 150 MPa). While rising from depth to 4.5 km, the melt underwent rapid decompression (0.5-2.6 MPa s-1) and H2O exsolution, driving late-stage crystallization of the groundmass. The fast ascent velocity (21-110 m s-1) while rising between 4.5 km and the surface induced turbulent (Re >103), annular flow development in the uppermost region of the conduit. We propose that cannonballs represent blebs of fluid magmas that underwent shear-driven detachment from the annulus of magma lining the conduit walls at depths lower than 4.5 km. The formation of such cannonballs is dictated by magma transport dynamics of low-viscosity, phenocryst-poor, and volatile-rich melts that rapidly accelerate within the shallow conduit.

  6. Hydrologic properties of shale and related argillaceous rocks

    Energy Technology Data Exchange (ETDEWEB)

    Moiseyev, A.N.


    This report is the result of a bibliographic study designed primarily to collect hydrologic data on American clay-rich rocks. The following information was also sought: stratigraphy, environment of deposition, mineralogic composition, and diagenetic changes. The collected numerical data are presented in tables which contain densities, porosities, and/or hydraulic conductivities of approximately 360 samples. Additional data include hydraulic diffusivities, resistivities, flow rates, and rock strengths. Geologic information suggests that large deposits of shale which may be suited for waste repository belong to all ages and were formed in both marine and continental environments. Of the studied units, the most promising are Paleozoic in the eastern half of the country, Mesozoic in the central part, and Cenozoic in the Gulf Coast area and the West. Less widespread units locally present some additional possibilities. Mineralogic investigations suggest that the smectite content in rocks shows a decrease in time (70% in Recent rocks; 35% in pre-Mesozoic rocks). Because of this predominance of smectite in younger rocks, the modeling of repositories in post-Paleozoic formations might require knowledge of additional and poorly known parameters. Results of investigations into the mathematical relationships between porosity and permeability (or hydralic conductivity) suggest that in situ permeabilities could be estimated from sonic logs and fluid pressure changes at depth. 16 figures, 8 tables.

  7. Hydrologic properties of shale and related argillaceous rocks

    International Nuclear Information System (INIS)

    Moiseyev, A.N.


    This report is the result of a bibliographic study designed primarily to collect hydrologic data on American clay-rich rocks. The following information was also sought: stratigraphy, environment of deposition, mineralogic composition, and diagenetic changes. The collected numerical data are presented in tables which contain densities, porosities, and/or hydraulic conductivities of approximately 360 samples. Additional data include hydraulic diffusivities, resistivities, flow rates, and rock strengths. Geologic information suggests that large deposits of shale which may be suited for waste repository belong to all ages and were formed in both marine and continental environments. Of the studied units, the most promising are Paleozoic in the eastern half of the country, Mesozoic in the central part, and Cenozoic in the Gulf Coast area and the West. Less widespread units locally present some additional possibilities. Mineralogic investigations suggest that the smectite content in rocks shows a decrease in time (70% in Recent rocks; 35% in pre-Mesozoic rocks). Because of this predominance of smectite in younger rocks, the modeling of repositories in post-Paleozoic formations might require knowledge of additional and poorly known parameters. Results of investigations into the mathematical relationships between porosity and permeability (or hydralic conductivity) suggest that in situ permeabilities could be estimated from sonic logs and fluid pressure changes at depth. 16 figures, 8 tables

  8. Cenozoic stratigraphy and structure of the Chesapeake Bay region (United States)

    Powars, David S.; Edwards, Lucy E.; Kidwell, Susan M.; Schindler, J. Stephen


    The Salisbury embayment is a broad tectonic downwarp that is filled by generally seaward-thickening, wedge-shaped deposits of the central Atlantic Coastal Plain. Our two-day field trip will take us to the western side of this embayment from the Fall Zone in Washington, D.C., to some of the bluffs along Aquia Creek and the Potomac River in Virginia, and then to the Calvert Cliffs on the western shore of the Chesapeake Bay. We will see fluvial-deltaic Cretaceous deposits of the Potomac Formation. We will then focus on Cenozoic marine deposits. Transgressive and highstand deposits are stacked upon each other with unconformities separating them; rarely are regressive or lowstand deposits preserved. The Paleocene and Eocene shallow shelf deposits consist of glauconitic, silty sands that contain varying amounts of marine shells. The Miocene shallow shelf deposits consist of diatomaceous silts and silty and shelly sands. The lithology, thickness, dip, preservation, and distribution of the succession of coastal plain sediments that were deposited in our field-trip area are, to a great extent, structurally controlled. Surficial and subsurface mapping using numerous continuous cores, auger holes, water-well data, and seismic surveys has documented some folds and numerous high-angle reverse and normal faults that offset Cretaceous and Cenozoic deposits. Many of these structures are rooted in early Mesozoic and/or Paleozoic NE-trending regional tectonic fault systems that underlie the Atlantic Coastal Plain. On Day 1, we will focus on two fault systems (stops 1–2; Stafford fault system and the Skinkers Neck–Brandywine fault system and their constituent fault zones and faults). We will then see (stops 3–5) a few of the remaining exposures of largely unlithified marine Paleocene and Eocene strata along the Virginia side of the Potomac River including the Paleocene-Eocene Thermal Maximum boundary clay. These exposures are capped by fluvial-estuarine Pleistocene terrace

  9. Cenozoic intracontinental deformation of the Kopeh Dagh Belt, Northeastern Iran (United States)

    Chu, Yang; Wan, Bo; Chen, Ling; Talebian, Morteza


    Compressional intracontinental orogens represent large tectonic zones far from plate boundaries. Since intracontinental mountain belts cannot be framed in the conventional plate tectonics theory, several hypotheses have been proposed to account for the formations of these mountain belts. The far-field effect of collision/subduction at plate margins is now well accepted for the origin and evolution of the intracontinental crust thickening, as exemplified by the Miocene tectonics of central Asia. In northern Iran, the Binalud-Alborz mountain belt witnessed the Triassic tectonothermal events (Cimmerian orogeny), which are interpreted as the result of the Paleotethys Ocean closure between the Eurasia and Central Iran blocks. The Kopeh Dagh Belt, located to the north of the Binalud-Alborz Belt, has experienced two significant tectonic phases: (1) Jurassic to Eocene rifting with more than 7 km of sediments; and (2) Late Eocene-Early Oligocene to Quaternary continuous compression. Due to the high seismicity, deformation associated with earthquakes has received more and more attention; however, the deformation pattern and architecture of this range remain poorly understood. Detailed field observations on the Cenozoic deformation indicate that the Kopeh Dagh Belt can be divided into a western zone and an eastern zone, separated by a series of dextral strike-slip faults, i.e. the Bakharden-Quchan Fault System. The eastern zone characterized by km-scale box-fold structures, associated with southwest-dipping reverse faults and top-to-the NE kinematics. In contrast, the western zone shows top-to-the SW kinematics, and the deformation intensifies from NE to SW. In the northern part of this zone, large-scale asymmetrical anticlines exhibit SW-directed vergence with subordinate thrusts and folds, whereas symmetrical anticlines are observed in the southern part. In regard to its tectonic feature, the Kopeh Dagh Belt is a typical Cenozoic intracontinental belt without ophiolites or

  10. Late Cretaceous and Cenozoic exhumation history of the Malay Peninsula (United States)

    François, Thomas; Daanen, Twan; Matenco, Liviu; Willingshofer, Ernst; van der Wal, Jorien


    The evolution of Peninsular Malaysia up to the collisional period in the Triassic is well described but the evolution since the collision between Indochina and the Sukhothai Arc in Triassic times is less well described in the literature. The processes affecting Peninsular Malaysia during the Jurassic up to current day times have to explain the emplacement multiple intrusions (the Stong Complex, and the Kemahang granite), the Jurassic/Cretaceous onland basins, the Cenozoic offshore basins, and the asymmetric extension, which caused the exhumation of Taku Schists dome. The orogenic period in Permo-Triassic times, which also formed the Bentong-Raub suture zone, resulted in thickening of the continental crust of current day Peninsular Malaysia due to the collision of the Indochina continental block and the Sukhothai Arc, and is related to the subduction of oceanic crust once present between these continental blocks. The Jurassic/Cretaceous is a period of extension, resulting in the onland Jurassic/Cretaceous basins, synchronous melting of the crust, resulting in the emplacement Stong Complex and the Kemahang granite and thinning of the continental crust on the scale of the Peninsular, followed by uplift of the Peninsular. Different models can explain these observations: continental root removal, oceanic slab detachment, or slab delamination. These models all describe the melting of the lower crust due to asthenospheric upwelling, resulting in uplift and subsequent extension either due to mantle convective movements or gravitational instabilities related to uplift. The Cenozoic period is dominated by extension and rapid exhumation in the area as documented by low temperature thermocrological ages The extension in this period is most likely related to the subduction, which resumed at 45 Ma, of the Australian plate beneath the Eurasian plate after it terminated in Cretaceous times due to the collision of an Australian microcontinental fragment with the Sunda margin in the

  11. Petrology of Gakkel Ridge Basalts: Preliminary Results (United States)

    Langmuir, C. H.; Lehnert, K.; Goldstein, S. L.; Michael, P.; Graham, D.; Schramm, B.


    The Gakkel Ridge offers the opportunity for a direct experiment in mantle melting and ridge dynamics. It is the slowest spreading ridge on the Earth, with a progressive change in spreading rate from 15mm/yr at the western end to 7mm/yr at the eastern end. No transform faults disrupt the melting regime, and spreading rate alone would appear to be the primary variable. During the AMORE2001 expedition of USCGC Healy and RV Polarstern, more than one hundred sampling stations were successfully completed mid-way through the cruise, with precise locations on new multibeam bathymetric charts (Kurras et al, Gauger et al, this meeting). More than 100 samples were analyzed on board for major elements, Sr and Ba by direct current plasma spectrometry. Because the cruise track encompasses a double-pass along most of the ridge, the on board data permitted testing of hypotheses formulated on the first pass by further sampling on the second pass. Models for the effect of decreasing spreading rate on melt composition predict progressively smaller extents of melting at greater depths eastward along the ridge. Instead, the ridge contains three distinct tectono-magmatic regimes. In the west, well-defined linear volcanic ridges occupy the center of the rift valley. The basalts exhibit a ''slow spreading local trend'' of negative correlation between Fe8 and Si8 and positive correlation between Na8 and Fe8. There is a well-defined geochemical gradient from more enriched incompatible trace element compositions in the west to depleted compositions in the east. At the eastern terminus of this region there are small volcanic cones with chemical compositions rare or unique among MORB. Samples with high MgO contain high TiO2 and Sr (3% and 200 ppm), and low SiO2 and Ba (46-47% and 20 ppm ). The low SiO2 and exceptionally high FeO (12%) suggest high pressures of melting. The high Sr and TiO2 but very low Ba of these samples suggest they were derived by very low extents of melting of a depleted

  12. Vesiculation of basaltic magma during eruption (United States)

    Mangan, Margaret T.; Cashman, Katharine V.; Newman, Sally


    Vesicle size distributions in vent lavas from the Pu'u'O'o-Kupaianaha eruption of Kilauea volcano are used to estimate nucleation and growth rates of H2O-rich gas bubbles in basaltic magma nearing the earth's surface (≤120 m depth). By using well-constrained estimates for the depth of volatile exsolution and magma ascent rate, nucleation rates of 35.9 events ⋅ cm-3 ⋅ s-1 and growth rates of 3.2 x 10-4cm/s are determined directly from size-distribution data. The results are consistent with diffusion-controlled growth as predicted by a parabolic growth law. This empirical approach is not subject to the limitations inherent in classical nucleation and growth theory and provides the first direct measurement of vesiculation kinetics in natural settings. In addition, perturbations in the measured size distributions are used to examine bubble escape, accumulation, and coalescence prior to the eruption of magma.

  13. Strontium stable isotope behaviour accompanying basalt weathering (United States)

    Burton, K. W.; Parkinson, I. J.; Gíslason, S. G. R.


    The strontium (Sr) stable isotope composition of rivers is strongly controlled by the balance of carbonate to silicate weathering (Krabbenhöft et al. 2010; Pearce et al. 2015). However, rivers draining silicate catchments possess distinctly heavier Sr stable isotope values than their bedrock compositions, pointing to significant fractionation during weathering. Some have argued for preferential release of heavy Sr from primary phases during chemical weathering, others for the formation of secondary weathering minerals that incorporate light isotopes. This study presents high-precision double-spike Sr stable isotope data for soils, rivers, ground waters and estuarine waters from Iceland, reflecting both natural weathering and societal impacts on those environments. The bedrock in Iceland is dominantly basaltic, d88/86Sr ≈ +0.27, extending to lighter values for rhyolites. Geothermal waters range from basaltic Sr stable compositions to those akin to seawater. Soil pore waters reflect a balance of input from primary mineral weathering, precipitation and litter recycling and removal into secondary phases and vegetation. Rivers and ground waters possess a wide range of d88/86Sr compositions from +0.101 to +0.858. Elemental and isotope data indicate that this fractionation primarily results from the formation or dissolution of secondary zeolite (d88/86Sr ≈ +0.10), but also carbonate (d88/86Sr ≈ +0.22) and sometimes anhydrite (d88/86Sr ≈ -0.73), driving the residual waters to heavier or lighter values, respectively. Estuarine waters largely reflect mixing with seawater, but are also be affected by adsorption onto particulates, again driving water to heavy values. Overall, these data indicate that the stability and nature of secondary weathering phases, exerts a strong control on the Sr stable isotope composition of silicate rivers. [1] Krabbenhöft et al. (2010) Geochim. Cosmochim. Acta 74, 4097-4109. [2] Pearce et al. (2015) Geochim. Cosmochim. Acta 157, 125-146.

  14. Characterization of fibers as rockwool for insulation obtained from canary islands basalts

    Directory of Open Access Journals (Sweden)

    Cáceres, J. M.


    Full Text Available Glass fibers in the shape of wool were obtained at laboratory scale from three samples of basaltic rocks from the Tenerife Island. The rockwool is widely used as thermal and acoustical insulation. The ability of these rocks to be fiberized was studied by means of the viscosity curves and can be quite improved by adding calcium and magnesium. The experimental fibers obtained from the rocks directly or mixed with either CaCO3 or CaMg(CO32 ye characterized in terms of chemical composition, microstructure and thermal and mechanical properties. These properties were compared with the ones determined for four commercial samples of rockcwool, founding that they are very close. This gives good prospects to these fibers from Canarian basalts as insulation material.

    Se ha obtenido fibra de vidrio en forma de lana, a escala de laboratorio, a partir de tres muestras de rocas basálticas de la Isla de Tenerife. La lana de roca se emplea extensamente como aislamiento térmico y acústico. La aptitud de estas rocas para su fibrado, estudiada mediante las curvas de viscosidad, mejora considerablemente con la adición de calcio y magnesio. Las fibras experimentales, obtenidas tanto a partir de las rocas directamente, como mezcladas en diferentes proporciones con CaCO3 o CaMg(CO32, se han caracterizado en lo referente a la composición química, la microestructura y propiedades térmicas y mecánicas. Así mismo, se han comparado estas propiedades con las determinadas para cuatro muestras comerciales de lana de roca, permitiendo comprobar que son bastante semejantes, lo que hace prever unas buenas cualidades para estas fibras de basaltos canarios en aplicaciones de aislamiento térmico y acústico.

  15. Determination of basalt physical and thermal properties at varying temperatures, pressures, and moisture contents. First progress report, fiscal year 1979

    International Nuclear Information System (INIS)

    Miller, R.J.; Bishop, R.C.


    This report is a summary of the rock mechanics testing done at the Earth Mechanics Institute of the Colorado School of Mines for Rockwell Hanford Operations under Subcontract SA-917. Cores were supplied from drill hole DC-6 on the Hanford Site, characterized geologically, and tested for thermal and physical properties for designing long-term underground storage of radioactive waste materials. This report presents the approved test procedures, results, and data analysis for this test series. Results indicated thermophysical properties similar to those of previously tested basalt cores from the Hanford area, but showed no significant trends; thus, generalizations are risky at this time. However, density was found to be a good guide to thermal and physical properties--higher density basalt cores showed significant improvements in physical and thermal properties

  16. Origin of the ca. 50 Ma Linzizong shoshonitic volcanic rocks in the eastern Gangdese arc, southern Tibet (United States)

    Liu, An-Lin; Wang, Qing; Zhu, Di-Cheng; Zhao, Zhi-Dan; Liu, Sheng-Ao; Wang, Rui; Dai, Jin-Gen; Zheng, Yuan-Chuan; Zhang, Liang-Liang


    The origin of the Eocene shoshonitic rocks within the upper part of the extensive Linzizong volcanic succession (i.e., the Pana Formation) in the Gangdese arc, southern Tibet remains unclear, inhibiting the detailed investigations on the crust-mantle interaction and mantle dynamics that operate the generation of the coeval magmatic flare-up in the arc. We report mineral composition, zircon U-Pb age and zircon Hf isotope, whole-rock element and Sr-Nd-Hf isotope data for the Pana Formation volcanic rocks from Pangduo, eastern Gangdese arc in southern Tibet. The Pana volcanic rocks from Pangduo include basalts, basaltic andesites, and dacites. SIMS and LA-ICPMS zircon U-Pb dating indicates that the Pangduo dacites were erupted at 50 ± 1 Ma, representing the volcanic equivalent of the coeval Gangdese Batholith that define a magmatic flare-up at 51 ± 1 Ma. The Pangduo volcanic rocks are exclusively shoshonitic, differing from typical subduction-related calc-alkaline volcanic rocks. The basalts have positive whole-rock ƐNd(t) (+1.7) and ƐHf(t) (+3.8) with high Zr abundances (121-169 ppm) and Zr/Y ratios (4.3-5.2), most likely derived from the partial melting of an enriched garnet-bearing lithospheric mantle that was metasomatized by subduction-related components with input from asthenosphere. Compared to the basalts, similar trace elemental patterns and decreased whole-rock ƐNd(t) (-3.5 to -3.3) and ƐHf(t) (-2.5 to -1.6) of the basaltic andesites can be attributed to the input of the ancient basement-derived material of the central Lhasa subterrane into the basaltic magmas. The coherent whole-rock Sr-Nd-Hf isotopic compositions ((87Sr/86Sr)i = 0.7064-0.7069, ƐNd(t) = -6.0 to -5.2, ƐHf(t) = -5.6 to -5.0) and varying zircon ƐHf(t) (-6.0 to +4.1) of the dacites can be interpreted by the partial melting of a hybrid lower crust source (juvenile and ancient lower crust) with incorporation of basement-derived components. Calculations of zircon-Ti temperature and whole-rock

  17. CERN Rocks

    CERN Document Server


    The 15th CERN Hardronic Festival took place on 17 July on the terrace of Rest 3 (Prévessin). Over 1000 people, from CERN and other International Organizations, came to enjoy the warm summer night, and to watch the best of the World's High Energy music. Jazz, rock, pop, country, metal, blues, funk and punk blasted out from 9 bands from the CERN Musiclub and Jazz club, alternating on two stages in a non-stop show.  The night reached its hottest point when The Canettes Blues Band got everybody dancing to sixties R&B tunes (pictured). Meanwhile, the bars and food vans were working at full capacity, under the expert management of the CERN Softball club, who were at the same time running a Softball tournament in the adjacent "Higgs Field". The Hardronic Festival is the main yearly CERN music event, and it is organized with the support of the Staff Association and the CERN Administration.

  18. Precious metal enrichment at low-redox in terrestrial native Fe-bearing basalts investigated using laser-ablation ICP-MS (United States)

    Howarth, Geoffrey H.; Day, James M. D.; Pernet-Fisher, John F.; Goodrich, Cyrena A.; Pearson, D. Graham; Luo, Yan; Ryabov, Viktor V.; Taylor, Lawrence A.


    Primary native Fe is a rare crystallizing phase from terrestrial basaltic magmas, requiring highly reducing conditions (fO2 abundances. Three localities are known globally where native Fe bearing mafic rocks occur: (1) Paleocene basalts of Disko Island, West Greenland; (2) a Miocene lava of the Bühl basalts, Germany; and (3) mafic intrusions associated with the Late Permian Siberian flood basalts. In this contribution, we report major- and minor-element compositions and HSE concentrations for the main alloy phases (FeNi metal and cohenite) and sulfide, for all three known global occurrences of native Fe bearing basalt. Total HSE abundances in metal grains, obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), are lowest in the Bühl basalt, (∼0.05 ppm), intermediate in the Disko Island basalts (4-8 ppm), and highest the Siberian Khungtukun and Dzhaltul intrusions (10-30 ppm). These differences demonstrate that, while native Fe formation is the result of carbonaceous crustal assimilation, HSE enrichment is not ubiquitous during this process. The Siberian occurrences are characterized by Pt PGE (PPGE: Pt, Pd) enrichment relative to the Ir PGE (IPGE: Rh, Ru, Ir, Os), consistent with models of early stage fractionation of olivine, chromite and metallic IPGE in staging magma reservoirs, prior to the addition of C-rich crustal materials in the shallow crust. Relative to Noril'sk Ni-Cu-PGE sulfide ores, the Siberian native Fe basalts are enriched in the PPGE relative to the IPGE, but exhibit Ru enrichments. In contrast, Disko Island native Fe rocks do not show significant fractionation of the PPGE from the IPGE, but have positive Re and Ru anomalies and high Os/Ir ratios. To reconcile these observations, we present a general model where some parental melts experienced early-stage crustal assimilation in staging magma reservoirs, prior to reduction by carbon-rich materials (e.g., Khungtukun, Dzhaltul), whereas basaltic parental melts to

  19. Stratigraphical framework of basaltic lavas in Torres Syncline main valley, southern Parana-Etendeka Volcanic Province (United States)

    Rossetti, Lucas M.; Lima, Evandro F.; Waichel, Breno L.; Scherer, Claiton M.; Barreto, Carla J.


    The Paraná-Etendeka Volcanic Province records the volcanism of the Early Cretaceous that precedes the fragmentation of the South-Gondwana supercontinent. Traditionally, investigations of these rocks prioritized the acquisition of geochemical and isotopic data, considering the volcanic stack as a monotonous succession of tabular flows. Torres Syncline is a tectonic structure located in southern Brazil and where the Parana-Etendeka basalts are well preserved. This work provides a detailed analysis of lithofacies and facies architecture, integrated to petrographic and geochemical data. We identified seven distinct lithofacies grouped into four facies associations related to different flow morphologies. The basaltic lava flows in the area can be divided into two contrasting units: Unit I - pahoehoe flow fields; and Unit II - simple rubbly flows. The first unit is build up by innumerous pahoehoe lava flows that cover the sandstones of Botucatu Formation. These flows occur as sheet pahoehoe, compound pahoehoe, and ponded lavas morphologies. Compound lavas are olivine-phyric basalts with intergranular pyroxenes. In ponded lavas and cores of sheet flows coarse plagioclase-phyric basalts are common. The first pahoehoe lavas are more primitive with higher contents of MgO. The emplacement of compound pahoehoe flows is related to low volume eruptions, while sheet lavas were emplaced during sustained eruptions. In contrast, Unit II is formed by thick simple rubbly lavas, characterized by a massive core and a brecciated/rubbly top. Petrographically these flows are characterized by plagioclase-phyric to aphyric basalts with high density of plagioclase crystals in the matrix. Chemically they are more differentiated lavas, and the emplacement is related to sustained high effusion rate eruptions. Both units are low TiO2 and have geochemical characteristics of Gramado magma type. The Torres Syncline main valley has a similar evolution when compared to other Large Igneous Provinces

  20. Hyper-localized carbon mineralization in diffusion-limited basalt fractures (United States)

    Menefee, A. H.; Giammar, D.; Ellis, B. R.


    Basalt formations could enable secure carbon sequestration through mineral trapping. CO2 injection acidifies formation brines and drives dissolution of the host rock, which releases divalent metal cations that combine with dissolved carbonate ions to form stable carbonate minerals. Here, a series of high-pressure flow-through experiments was conducted to evaluate how transport limitations and geochemical gradients drive microscale carbonation reactions in fractured basalts. To isolate advection- and diffusion-controlled zones, surfaces of saw-cut basalt cores were milled to create one primary flow channel adjoined by four dead-end fracture pathways. In the first experiment, a representative basalt brine (6.3 mM NaHCO3) equilibrated with CO2 (100ºC, 10 MPa) was injected at 1 mL/h under 20 MPa confining stress. The second experiment was conducted under the same physical conditions but [NaHCO3] was elevated to 640 mM, and in the third, temperature was also raised to 150ºC. Effluent chemistry was monitored via ICP-MS to infer dissolution trends and calibrate reactive transport models. Reacted cores were characterized using x-ray computed tomography (xCT), optical microscopy, scanning electron microscopy, and Raman spectroscopy. Carbonation occurred in all experiments but increased in experiments with higher alkalinity and higher temperature. At low [NaHCO3], secondary precipitate coatings formed distinct reaction fronts that varied with distance into dead-end fractures. Reactive transport modeling demonstrated that these reactions fronts were due to sharp gradients in pH and dissolved inorganic carbon. Carbonation was restricted to transport-limited vugs and pores between the confined core surfaces and was highly localized on reactive primary mineral grains (e.g. pyroxene) that contributed major divalent cations. Increasing [NaHCO3] by two orders of magnitude significantly enhanced carbonation and promoted Mg and Fe uptake into carbonates. While xCT scans revealed

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

    International Nuclear Information System (INIS)

    Abbady, A G.E.; Arabi, A.M.; Abbay, A.


    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

  2. The diffusion of some radionuclides in local rocks collected from potential repository in Syria

    International Nuclear Information System (INIS)

    Othman, Ibrahim; Abou Jamous, Jamal


    Diffusion factor was estimated for 137 Cs in local rocks marl, limestone, and basalt. Slab activity measuring was constructed. Factors affecting the 137 Cs diffusion has been studied. These are dynamic state of water, length of contacting time and the concentration of radioisotope. (author). 9 refs., 12 figs., 6 tabs

  3. Are Majhgawan–Hinota pipe rocks truly group-I kimberlite?

    Indian Academy of Sciences (India)

    and Paul 1989; Halder and Ghosh 1978, 1981) to designate the rocks as micaceous kimberlite/basaltic kimberlite and kimberlite breccia. Kent et al (1998) preferred to call the ... from Damodar Valley, eastern India (Kent et al 1998). The majority of the ..... 27: Average (6 analyses) Leucite Hill madupitic lamproite. 28: Olivine ...

  4. Cenozoic mountain building on the northeastern Tibetan Plateau (United States)

    Lease, Richard O.


    Northeastern Tibetan Plateau growth illuminates the kinematics, geodynamics, and climatic consequences of large-scale orogenesis, yet only recently have data become available to outline the spatiotemporal pattern and rates of this growth. I review the tectonic history of range growth across the plateau margin north of the Kunlun fault (35°–40°N) and east of the Qaidam basin (98°–107°E), synthesizing records from fault-bounded mountain ranges and adjacent sedimentary basins. Deformation began in Eocene time shortly after India-Asia collision, but the northeastern orogen boundary has largely remained stationary since this time. Widespread middle Miocene–Holocene range growth is portrayed by accelerated deformation, uplift, erosion, and deposition across northeastern Tibet. The extent of deformation, however, only expanded ~150 km outward to the north and east and ~150 km laterally to the west. A middle Miocene reorganization of deformation characterized by shortening at various orientations heralds the onset of the modern kinematic regime where shortening is coupled to strike slip. This regime is responsible for the majority of Cenozoic crustal shortening and thickening and the development of the northeastern Tibetan Plateau.

  5. Early Cenozoic "dome like" exhumation around the Irish Sea (United States)

    Doepke, Daniel; Cogné, Nathan; Chew, David; Stuart, Fin


    Despite decades of research the Early Cenozoic exhumation history of Ireland and Britain is still poorly understood and subject to contentious debate (see Davis et al., 2012 and subsequent comments). Previous studies have attributed the Cenozoic exhumation history of Ireland and Britain mainly to: (a) Paleogene - Neogene far-field stress between the opening of the North Atlantic Ocean and the Alpine collision (Ziegler et al., 1995; Hillis et al., 2008) or (b) early Paleogene mantle driven magmatic underplating associated with the development of the proto-Iceland mantle plume beneath the Irish Sea (Brodie and White, 1994; Al-Kindi et al., 2003). The major differences between the two hypotheses are the pattern and timing of spatial exhumation. This project thus seeks to investigate the timing and mechanisms of late Mesozoic - early Cenozoic exhumation on the onshore part of the British Isles by using a combination of apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) data, which we then model using the QTQt program of Gallagher (2012) to better constrain the modelled thermal histories. Our studied area centres on the margins of the Irish Sea, but includes all Ireland and western Britain. Overall we analysed 74 samples for AFT and 66 samples for AHe dating. In particular, our results include ten pseudo-vertical profiles. The AFT ages display a wide range of ages from early Carboniferous in Scotland to early Eocene in central Ireland. Our AHe ages range from mid Permian on Shetland to Eocene Ft-corrected. The AFT data do not show any specific spatial distribution, however, the Ft-corrected AHe ages around the Irish Sea only focus around late Cretaceous to Eocene suggesting an important thermal event around this time. The modelled thermal histories of samples located around the Irish Sea and western Scotland show a clear late Cretaceous to early Paleogene cooling event which is not present elsewhere. The distribution of this cooling event is broadly consistent

  6. Cenozoic sea level and the rise of modern rimmed atolls (United States)

    Toomey, Michael; Ashton, Andrew; Raymo, Maureen E.; Perron, J. Taylor


    Sea-level records from atolls, potentially spanning the Cenozoic, have been largely overlooked, in part because the processes that control atoll form (reef accretion, carbonate dissolution, sediment transport, vertical motion) are complex and, for many islands, unconstrained on million-year timescales. Here we combine existing observations of atoll morphology and corelog stratigraphy from Enewetak Atoll with a numerical model to (1) constrain the relative rates of subsidence, dissolution and sedimentation that have shaped modern Pacific atolls and (2) construct a record of sea level over the past 8.5 million years. Both the stratigraphy from Enewetak Atoll (constrained by a subsidence rate of ~ 20 m/Myr) and our numerical modeling results suggest that low sea levels (50–125 m below present), and presumably bi-polar glaciations, occurred throughout much of the late Miocene, preceding the warmer climate of the Pliocene, when sea level was higher than present. Carbonate dissolution through the subsequent sea-level fall that accompanied the onset of large glacial cycles in the late Pliocene, along with rapid highstand constructional reef growth, likely drove development of the rimmed atoll morphology we see today.

  7. Changing provenance of late Cenozoic sediments in the Jianghan Basin

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    Lei Shao


    Full Text Available The Yangtze River is one of the most important components of the East Asia river system. In this study, sediments in the Jianghan Basin, middle Yangtze River, were selected for trace element and rare earth element (REE measurements, in order to decipher information on the change of sediment provenance and evolution of the Yangtze River. According to the elemental variations, the late Cenozoic sediments of the Jianghan Basin could be divided into four parts. During 2.68–2.28 Ma and 1.25–0 Ma, provenance of the sediments was consistent, whereas sediments were derived from variable sources during 2.28–1.25 Ma. Comparison of the elemental compositions between the Pliocene and Quaternary sediments revealed a change in sediment source from a more felsic source area to a more basic source area around the Pliocene–Quaternary boundary. Input from the Emeishan LIP should account for this provenance change. Based on the provenance analysis of sediments in the Jianghan Basin, we infer that the Yangtze River developed into a large river with its drainage basin extended to the Emeishan LIP no later than the Pliocene–Quaternary boundary.

  8. Cenozoic cool-water limestones, Eucla platform, Southern Australia

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    James, N.P. (Queen' s Univ., Kingston, Ontario (Canada)); Bone, Y. (Univ. of Adelaide (Australia))


    Evidence is accumulating that modern and Cenozoic cool-water (temperate water) carbonate sediments may be the best facies analogs for many open-shelf, middle to late Paleozoic carbonates; yet there are comparatively few studies of such deposits. One important example is the extensive Eucla platform, a 350,000-km{sup 2} Eocene to Miocene shelf that caps the southern Australian miogeocline. Only the inner part, which lies beneath the Nullarbor Plain, has been examined in any detail. Sediments are of the bryomol assemblage - mainly bryozoan, echinoid, mollusk, and foraminifera remains with local concentrations of brachiopods. Most deposits formed by the spontaneous postmortem disintegration of erect, flexible cellariiform cheilostome and crisiform cyclostome bryozoans, cool-water analogs of codiacean algae. Facies range from incipiently drowned deep-shelf muddy sediments to ubiquitous open-shelf skeletal wackestones and packstones to local shallow-water, high-energy sand shoals. Because of accumulation rates an order of magnitude less than tropical shelf carbollates, eustasy is expressed as hardgrounds and karst surfaces; there are no muddy tidal flats. The cool-water platform sequence is capped by warmer water facies rich in aragonitic mollusks and calcareous algae with local concentrations of hermatypic corals. This change, which takes place across a bedding plane and reflects a shift in oceanic circulation patterns, highlights the fact that subtle changes in water temperature can result in the formation of dramatically different carbonate facies.

  9. Geochemical characterization of basalts from west of Khash (SE Iran: an approach to the nature of the mantle source

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    Zahra Firouzkouhi


    Full Text Available Monogenic basaltic cinder cones and lava flows from west of Khash are part of volcanic arc of northern Makran, formed as a result of subduction of Oman oceanic lithosphere beneath the Eurasian plate. The basalts belong to medium-K calc-alkaline series as they contain high Al2O3 (16.5- 19.04 wt. % and CaO (8.4- 12.0 wt. % and moderate amounts of K2O (0.5- 1.1 wt. %. They share arc geochemical features such as high LILE/HFSE ([Rb/Zr]N-MORB up to 19 LILE/LREE ([Ba/La]N-MORB up to 4.86 and LREE/HREE ([La/Yb]N-MORB up to 10, and depletion of Ta, Nb, Zr, and Ti relative to N-MORB. Partial melting models indicate that near-primary basalts were derived from an enriched source type mantle wedge peridotite after low to medium degrees (2-10% of partial melting. This source peridotite was enriched in LREE and LILE, by subduction derived fluids in the supra-subduction zone. Negative correlation of Th/La vs. Sm/La, and relationships between Pb/Ce and Th/Nb values of the studied basalts which are between two end compositions of global subducting sediment (GLOSS and N-MORB are indicative of significant contribution of subducting sediments to the genesis of the basaltic rocks. Estimates made using binary mixing model are indicative of about 16% of sediment participation in the magma genesis. Low Pb/Ce ratio (1.6 - 11.1, compared to OIB (>20 may be a signature of participation of fluids resulted from dehydration of the subducting slab

  10. Correlating mode-I fracture toughness and mechanical properties of heat-treated crystalline rocks

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    Mayukh Talukdar


    Full Text Available For the effect of thermal treatment on the mode-I fracture toughness (FT, three crystalline rocks (two basalts and one tonalite were experimentally investigated. Semi-circular bend specimens of the rocks were prepared following the method suggested by the International Society for Rock Mechanics (ISRM and were treated at various temperatures ranging from room temperature (25 °C to 600 °C. Mode-I FT was correlated with tensile strength (TS, ultrasonic velocities, and Young's modulus (YM. Additionally, petrographic and X-ray diffraction analyses were carried out to find the chemical changes resulting from the heat treatment. Further, scanning electron microscopy (SEM was conducted to observe the micro structural changes when subjected to high temperatures. These experiments demonstrate that heat treatment has a strong negative impact on the FT and mechanical properties of the rocks. From room temperature to 600 °C, mode-I FT values of massive basalt, giant plagioclase basalt, and tonalite were reduced by nearly 52%, 68%, and 64%, respectively. Also, at all temperature levels, FT and mechanical properties are found to be exponentially correlated. However, the exact nature of the relationship mainly depends on rock type. Besides, TS was found to be a better indicator of degradation degree than the mode-I FT. SEM images show that micro crack density and structural disintegration of the mineral grains increase with temperature. These physical changes confirm the observed reduction in the stiffness of heat-treated crystalline rocks.

  11. Fission-track evidence for apparent out-of-sequence Cenozoic deformation along the Philip Smith Mountain front, northeastern Brooks Range, Alaska (United States)

    O'Sullivan, Paul B.; Wallace, Wesley K.; Murphy, John M.


    The northeastern Brooks Range (NEBR), bounded to the northwest by the Philip Smith Mountain front (PSMF), advanced northward from the east-trending main axis of the Brooks Range in Cenozoic time. The evolution of the PSMF is difficult to assess by conventional means because of a limited Cenozoic depositional record and poor exposures between the mountain front and the deformation front. 49 surface and 3 subsurface samples were collected along the northern flank of the PSMF to evaluate its thermal and tectonic history using apatite fission-track (AFT) data. Time-temperature modelling of the AFT data indicate that rocks exposed along the PSMF experienced maximum paleotemperatures in Late Cretaceous to Paleocene time and subsequently cooled during three episodes of km-scale denudation, at ˜60, ˜46, and ˜35 Ma. Apparent out-of-sequence deformation is indicated because successively younger ages are recorded to the southeast, approaching the range front from the foreland. This may reflect a hindward-propagating thrust sequence or apparent out-of-sequence deformation above a forward-propagating basal detachment due either to successive drops in the basal detachment or to deformation within the wedge. These results highlight the usefulness of fission-track data in revealing the age and distribution of tectonically driven unroofing and associated structural boundaries, particularly where they are otherwise difficult to recognize.

  12. Geology, geochemistry and petrology of basalts from Paraná Continental Magmatic Province in the Araguari, Uberlândia, Uberaba and Sacramento regions, Minas Gerais state, Brazil

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    Lucia Castanheira de Moraes


    Full Text Available Abstract: This study covers the region between the cities of Sacramento and Araguari/Uberlândia (Minas Gerais State, Brazil, where basalt flows from the Paraná Continental Magmatic Province outcrop. The investigated rocks present tholeiitic signature, with high titanium content, and are classified as Pitanga magma-type. The preserved basalt thickness is between 10 and 200 meters and individual flows do not exceed 15 meters thick. Flows were identified as sheet lobes, smaller and thinner flows units - stacked laterally and vertically forming compound lavas -, or frontal, centimetric lobes. The basalt flows show decimetric to metric intercalations of clastic sedimentary rock, with depositional characteristics that can vary from aeolian to lacustrine, and are important markers on prevailing environmental conditions. The plagioclases are dominantly labradorite and pyroxene is augite, whereas olivine can be hyalosiderite or hortonolite/ferrohortonolite. The behavior of the major, minor and trace elements is compatible with the presence of at least two parental magmas, which were subjected to fractional crystallization mainly of plagioclase, clinopyroxene, ilmenite and magnetite. There is a chemistry distinction between basalts from Sacramento to those from Araguari/Uberlândia region, the former one showing more evolved than the last one. The high (La/LuN values are indicative of partial melting of a garnet peridotite, while the Rare Earth Elements (REE values are indicative of fractional crystallization.

  13. Heat and Groundwater Flow through Continental Flood Basalt Provinces: Insights Gained from Alternative Models of Permeability/Depth Relationships for the Columbia Plateau, USA (United States)

    Burns, E. R.; Williams, C. F.; Ingebritsen, S.; Voss, C. I.; Spane, F.; DeAngelo, J.


    Heat-flow mapping of the western USA has identified an apparent low-heat-flow anomaly coincident with the Columbia Plateau Regional Aquifer System, a thick sequence of basalt aquifers within the Columbia River Basalt Group (CRBG). A heat and mass transport model (SUTRA) was used to evaluate the potential impact of groundwater flow on heat flow along two different regional groundwater flow paths. Limited in situ permeability (k) data from the CRBG are compatible with a steep permeability decrease (~3.5 orders of magnitude) at 600-900 m depth and ~40oC. Numerical simulations incorporating this permeability decrease demonstrate that regional groundwater flow can explain lower-than-expected heat flow in these highly anisotropic (kx/kz ~104) continental flood basalts. Simulation results indicate that the abrupt reduction in permeability at ~600 m depth results in an equivalently abrupt transition from a shallow region where heat flow is affected by groundwater flow to a deeper region of conduction-dominated heat flow. Abrupt k decreases at similar temperatures have also been observed in the volcanic rocks of the adjacent Cascade Range volcanic arc and at Kilauea Volcano, Hawaii, where they result from low-temperature hydrothermal alteration. Because pore filling hydrothermal minerals are largely controlled by the major mineral assemblages of the volcanic rocks, other continental flood basalt provinces may also have large permeability changes at depths corresponding to ~40oC.

  14. Cenozoic calcretes from the Teruel Graben, Spain: microstructure, stable isotope geochemistry and environmental significance (United States)

    Alonso-Zarza, A. M.; Arenas, C.


    In the Teruel Graben (northeast Spain), laminar and nodular calcretes formed in a variety of Cenozoic deposits, ranging in age from Palaeogene to Pleistocene. These calcretes developed in a relatively small area under the influence of the same highlands. Consequently, differences in their microstructure and isotopic composition (C and O) must be related to differences in host rock, climate, vegetation and duration of development. Nine profiles developed in different sedimentary settings, from proximal areas to lacustrine environments, were studied to determine whether the microstructure and stable isotope composition changed during the Cenozoic. These characteristics might be used as indicators of the prevailing climate and vegetation, and reveal any changes that occurred during this time. Most of the laminar calcretes studied are compound profiles that formed on hard substrates (e.g., Jurassic limestones) or coarse detrital deposits (e.g., Palaeogene, Pliocene and Plio-Pleistocene sandstones and conglomerates). These profiles formed in proximal areas of the basin and also in fluvial terraces. Microstructures include biogenic features such as alveolar septal structures, root tubes, calcified root cells and calcified organic filaments. Underside coatings of micrite and fibrous vadose cements are common around gravel clasts. On the other side, spherulites are only preserved at the very top of the youngest calcretes. Nodular calcretes developed on fine detrital substrates (e.g., on Palaeogene, Miocene and Pliocene red mudstones and sandy mudstones of distal alluvial and floodplain environments), and in some places grade vertically into palustrine limestones. The nodules consist of micrite and were elongated vertically, show desiccation cracks and mottling, micritic coatings, some alveolar septal structures, and root traces. Microcodium of type 1 occurs in both laminar and nodular calcretes, but only in those of Palaeogene age, while calcified root cells ( Microcodium

  15. The Thickness and Volume of Young Basalts Within Mare Imbrium (United States)

    Chen, Yuan; Li, Chunlai; Ren, Xin; Liu, Jianjun; Wu, Yunzhao; Lu, Yu; Cai, Wei; Zhang, Xunyu


    Basaltic volcanism is one of the most important geologic processes of the Moon. Research on the thickness and volume of late-stage basalts of Mare Imbrium helps better understand the source of lunar volcanism and eruption styles. Based on whether apparent flow fronts exist or not, the late-stage basalts within Mare Imbrium were divided into two groups, namely, Upper Eratosthenian basalts (UEm) and Lower Eratosthenian basalts (LEm). Employing the topographic profile analysis method for UEm and the crater excavation technique for LEm, we studied the thickness and distribution of Eratosthenian basalts in Mare Imbrium. For the UEm units, their thicknesses were estimated to be 16-34 (±2) m with several layers of individual lava ( 8-13 m) inside. The estimated thickness of LEm units was 14-45(±1) m, with a trend of reducing thickness from north to south. The measured thickness of late-stage basalts around the Chang'E-3 landing site ( 37 ± 1 m) was quite close to the results acquired by the lunar penetrating radar carried on board the Yutu Rover ( 35 m). The total volume of the late-stage basalts in Mare Imbrium was calculated to be 8,671 (±320) km3, which is 4 times lower than that of Schaber's estimation ( 4 × 104 km3). Our results indicate that the actual volume is much lower than previous estimates of the final stage of the late basaltic eruption of Mare Imbrium. Together, the area flux and transport distance of the lava flows gradually decreased with time. These results suggest that late-stage volcanic evolution of the Moon might be revised.

  16. Bioleaching of ilmenite and basalt in the presence of iron-oxidizing and iron-scavenging bacteria (United States)

    Navarrete, Jesica U.; Cappelle, Ian J.; Schnittker, Kimberlin; Borrok, David M.


    Bioleaching has been suggested as an alternative to traditional mining techniques in extraterrestrial environments because it does not require extensive infrastructure and bulky hardware. In situ bioleaching of silicate minerals, such as those found on the moon or Mars, has been proposed as a feasible alternative to traditional extraction techniques that require either extreme heat and/or substantial chemical treatment. In this study, we investigated the biotic and abiotic leaching of basaltic rocks (analogues to those found on the moon and Mars) and the mineral ilmenite (FeTiO3) in aqueous environments under acidic (pH ˜ 2.5) and circumneutral pH conditions. The biological leaching experiments were conducted using Acidithiobacillus ferrooxidans, an iron (Fe)-oxidizing bacteria, and Pseudomonas mendocina, an Fe-scavenging bacteria. We found that both strains were able to grow using the Fe(II) derived from the tested basaltic rocks and ilmenite. Although silica leaching rates were the same or slightly less in the bacterial systems with A. ferrooxidans than in the abiotic control systems, the extent of Fe, Al and Ti released (and re-precipitated in new solid phases) was actually greater in the biotic systems. This is likely because the Fe(II) leached from the basalt was immediately oxidized by A. ferrooxidans, and precipitated into Fe(III) phases which causes a change in the equilibrium of the system, i.e. Le Chatelier's principle. Iron(II) in the abiotic experiment was allowed to build up in solution which led to a decrease in its overall release rate. For example, the percentage of Fe, Al and Ti leached (dissolved + reactive mineral precipitates) from the Mars simulant in the A. ferrooxidans experimental system was 34, 41 and 13% of the total Fe, Al and Ti in the basalt, respectively, while the abiotic experimental system released totals of only 11, 25 and 2%. There was, however, no measurable difference in the amounts of Fe and Ti released from ilmenite in the

  17. The petrology and geochemistry of high cascade volcanics in southern Washington: Mount Saint Helens volcano and the Indian Heaven basalt field (United States)

    Smith, D. R.


    Mount St. Helens volcano (Washington, USA) was characterized by four eruptive periods during the last 2200 years. Eruptive products include a wide spectrum of rock types including basaltic to andesitic lavas, andesitic to dacitic pyroclastic flows and tephra, and dacite domes. The major and trace element compositions of some andesites and dacites are broadly consistent with their derivation from a basaltic andesite parental magma by fractional crystallization processes involving the observed phenocryst assemblages. However, the strontium and oxygen isotopic compositions of representative samples of the Mount St. Helens suite indicate that closed system processes cannot explain the isotopic variations. The isotopic ratios are positively correlated with one another and with bulk composition (SiO2, Mg number, etc.). The isotopic variations and trace element data support an origin of some intermediate and silicic rock types by combined processes of assimilation and fractional crystallization.

  18. Spreading and collapse of big basaltic volcanoes (United States)

    Puglisi, Giuseppe; Bonforte, Alessandro; Guglielmino, Francesco; Peltier, Aline; Poland, Michael


    Among the different types of volcanoes, basaltic ones usually form the most voluminous edifices. Because volcanoes are growing on a pre-existing landscape, the geologic and structural framework of the basement (and earlier volcanic landforms) influences the stress regime, seismicity, and volcanic activity. Conversely, the masses of these volcanoes introduce a morphological anomaly that affects neighboring areas. Growth of a volcano disturbs the tectonic framework of the region, clamps and unclamps existing faults (some of which may be reactivated by the new stress field), and deforms the substratum. A volcano's weight on its basement can trigger edifice spreading and collapse that can affect populated areas even at significant distance. Volcano instability can also be driven by slow tectonic deformation and magmatic intrusion. The manifestations of instability span a range of temporal and spatial scales, ranging from slow creep on individual faults to large earthquakes affecting a broad area. In the frame of MED-SVU project, our work aims to investigate the relation between basement setting and volcanic activity and stability at three Supersite volcanoes: Etna (Sicily, Italy), Kilauea (Island of Hawaii, USA) and Piton de la Fournaise (La Reunion Island, France). These volcanoes host frequent eruptive activity (effusive and explosive) and share common features indicating lateral spreading and collapse, yet they are characterized by different morphologies, dimensions, and tectonic frameworks. For instance, the basaltic ocean island volcanoes of Kilauea and Piton de la Fournaise are near the active ends of long hotspot chains while Mt. Etna has developed at junction along a convergent margin between the African and Eurasian plates and a passive margin separating the oceanic Ionian crust from the African continental crust. Magma supply and plate velocity also differ in the three settings, as to the sizes of the edifices and the extents of their rift zones. These

  19. Rollerjaw Rock Crusher (United States)

    Peters, Gregory; Brown, Kyle; Fuerstenau, Stephen


    The rollerjaw rock crusher melds the concepts of jaw crushing and roll crushing long employed in the mining and rock-crushing industries. Rollerjaw rock crushers have been proposed for inclusion in geological exploration missions on Mars, where they would be used to pulverize rock samples into powders in the tens of micrometer particle size range required for analysis by scientific instruments.

  20. Microbial colonization of basaltic glasses in hydrothermal organic-rich sediments at Guaymas Basin (United States)

    Callac, Nolwenn; Rommevaux-Jestin, Céline; Rouxel, Olivier; Lesongeur, Françoise; Liorzou, Céline; Bollinger, Claire; Ferrant, Antony; Godfroy, Anne


    Oceanic basalts host diverse microbial communities with various metabolisms involved in C, N, S, and Fe biogeochemical cycles which may contribute to mineral and glass alteration processes at, and below the seafloor. In order to study the microbial colonization on basaltic glasses and their potential biotic/abiotic weathering products, two colonization modules called AISICS (“Autonomous in situ Instrumented Colonization System”) were deployed in hydrothermal deep-sea sediments at the Guaymas Basin for 8 days and 22 days. Each AISICS module contained 18 colonizers (including sterile controls) filled with basaltic glasses of contrasting composition. Chemical analyses of ambient fluids sampled through the colonizers showed a greater contribution of hydrothermal fluids (maximum temperature 57.6°C) for the module deployed during the longer time period. For each colonizer, the phylogenetic diversity and metabolic function of bacterial and archaeal communities were explored using a molecular approach by cloning and sequencing. Results showed large microbial diversity in all colonizers. The bacterial distribution was primarily linked to the deployment duration, as well as the depth for the short deployment time module. Some 16s rRNA sequences formed a new cluster of Epsilonproteobacteria. Within the Archaea the retrieved diversity could not be linked to either duration, depth or substrata. However, mcrA gene sequences belonging to the ANME-1 mcrA-guaymas cluster were found sometimes associated with their putative sulfate-reducers syntrophs depending on the colonizers. Although no specific glass alteration texture was identified, nano-crystals of barite and pyrite were observed in close association with organic matter, suggesting a possible biological mediation. This study gives new insights into the colonization steps of volcanic rock substrates and the capability of microbial communities to exploit new environmental conditions. PMID:23986754

  1. Magmatic inclusions in rhyolites, contaminated basalts, and compositional zonation beneath the Coso volcanic field, California (United States)

    Bacon, C.R.; Metz, J.


    Basaltic lava flows and high-silica rhyolite domes form the Pleistocene part of the Coso volcanic field in southeastern California. The distribution of vents maps the areal zonation inferred for the upper parts of the Coso magmatic system. Subalkalic basalts (Coso volcanic field contain sparse andesitic inclusions (55-61% SiO2). Pillow-like forms, intricate commingling and local diffusive mixing of andesite and rhyolite at contacts, concentric vesicle distribution, and crystal morphologies indicative of undercooling show that inclusions were incorporated in their rhyolitic hosts as blobs of magma. Inclusions were probably dispersed throughout small volumes of rhyolitic magma by convective (mechanical) mixing. Inclusion magma was formed by mixing (hybridization) at the interface between basaltic and rhyolitic magmas that coexisted in vertically zoned igneous systems. Relict phenocrysts and the bulk compositions of inclusions suggest that silicic endmembers were less differentiated than erupted high-silica rhyolite. Changes in inferred endmembers of magma mixtures with time suggest that the steepness of chemical gradients near the silicic/mafic interface in the zoned reservoir may have decreased as the system matured, although a high-silica rhyolitic cap persisted. The Coso example is an extreme case of large thermal and compositional contrast between inclusion and host magmas; lesser differences between intermediate composition magmas and inclusions lead to undercooling phenomena that suggest smaller ??T. Vertical compositional zonation in magma chambers has been documented through study of products of voluminous pyroclastic eruptions. Magmatic inclusions in volcanic rocks provide evidence for compositional zonation and mixing processes in igneous systems when only lava is erupted. ?? 1984 Springer-Verlag.

  2. Basalt FRP Spike Repairing of Wood Beams

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    Luca Righetti


    Full Text Available This article describes aspects within an experimental program aimed at improving the structural performance of cracked solid fir-wood beams repaired with Basalt Fiber Reinforced Polymer (BFRP spikes. Fir wood is characterized by its low density, low compression strength, and high level of defects, and it is likely to distort when dried and tends to fail under tension due to the presence of cracks, knots, or grain deviation. The proposed repair technique consists of the insertion of BFRP spikes into timber beams to restore the continuity of cracked sections. The experimental efforts deal with the evaluation of the bending strength and deformation properties of 24 timber beams. An artificially simulated cracking was produced by cutting the wood beams in half or notching. The obtained results for the repaired beams were compared with those of solid undamaged and damaged beams, and increases of beam capacity, bending strength and of modulus of elasticity, and analysis of failure modes was discussed. For notched beams, the application of the BFRP spikes was able to restore the original bending capacity of undamaged beams, while only a small part of the original capacity was recovered for beams that were cut in half.

  3. Laser Ar-39-Ar-40 study of Apollo 17 basalts (United States)

    Schaeffer, O. A.; Mueller, H. W.; Grove, T. L.


    Three Apollo 17 basalts were studied by the laser Ar-39-Ar-40 method. The 70215 basalt has a normal well-behaved Ar-39-Ar-40 release pattern; the 70017 basalt has a disturbed release pattern which indicates a limited intermediate maximum age followed by a broad low-age region; and the 75035 basalt has a pattern initially similar to 70017 that is followed by a high-temperature maximum age. The laser study shows that all mineral systems in 70215 have small and uniform temperature losses, while the laser-determined ages for 70017 and 75035 are, apparently, primarily controlled by the minerals containing mesostasis inclusions. It is possible that the drop in ages observed by the conventional Ar-39-Ar-40 method was due not only to recoil of Ar-39 during neutron irradiation but also to gas loss from some minerals. It is suggested that the plagioclases are the best minerals to use for a reliable age.

  4. Evaluation of alternative spent fuel waste package concepts for a repository in Basalt

    International Nuclear Information System (INIS)

    Hall, G.V.B.; Nair, B.R.


    The United States government has established a program for the disposal of spent nuclear fuel and high-level radioactive waste. The Nuclear Waste Policy Act (NWPA) of 1982 requires the first nuclear waste repository to begin receiving high-level radioactive waste in 1998. One of the potentially acceptable sites currently being evaluated is the Hanford Site in the Pasco Basin in the state of Washington where the host rock is basalt. Under the direction of the United States Department of Energy (DOE), Rockwell International's Rockwell Hanford Operations (RHO) has initiated the Basalt Waste Isolation Project (BWIP). The BWIP must design waste packages for emplacement in the repository. As part of the BWIP waste package development program, several alternative designs were considered for the disposal of spent nuclear fuel. This paper describes the concepts that were evaluated, the criteria that was developed for judging their relative merits, and the methodology that was employed. The results of the evaluation show that a Pipe-In-Tunnel design, which uses a long carbon steel pipe for the containment barrier for multiple packages of consolidated spent fuel, has the highest rating. Other designs which had high ratings are also discussed

  5. 182W evidence from flood basalt lavas for the long-term survival of primordial mantle (United States)

    Rizo Garza, H. L.; Walker, R. J.; Carlson, R.; Horan, M. F.; Mukhopadhyay, S.; Francis, D.; Jackson, M. G.


    How much of the chemical heterogeneity present in mantle today dates to processes that occurred during Earth's planetary formation stage remains an unanswered question. Geochemical observations obtained from short-lived radiogenic isotope systems, however, provide important insights. Tungsten isotope data for flood basalt lavas from two large igneous provinces, the North Atlantic Igneous Province ( 60 Ma) and the Ontong Java Plateau ( 120 Ma), show well resolved 182W excesses, compared with terrestrial standards that are presumed to be representative of the present bulk mantle. These W isotope results, thus, indicate that one or more mantle domains formed very early in Earth history and have been preserved well into the Phanerozoic eon. The flood basalts from Baffin Bay contain among the highest 3He/4He ratios ever measured, as well as Pb and 143Nd isotopic compositions, and D/H ratios consistent with a chemically primitive, un-degassed mantle source. Ontong Java is the Earth's largest known volcanic province and shares chemical and isotopic similarities with the Baffin Bay lavas, indicative of a similarly primitive mantle source. The 182W-enriched nature of the mantle sources of rocks from both locations indicates that their primitive characteristics were likely isolated in a deep mantle reservoir within the first 50 Ma of Solar System history. The correlation between large low seismic shear velocity provinces (LLSVPs) and the distribution of reconstructed eruption sites of these large igneous provinces makes the LLSVPs possible candidate domains for the required primitive and un-degassed reservoirs.

  6. Radiogenic isotopes in enriched mid-ocean ridge basalts from Explorer Ridge, northeast Pacific Ocean (United States)

    Cousens, Brian; Weis, Dominique; Constantin, Marc; Scott, Steve


    Extreme gradients in topography related to variations in magma supply are observed on the Southern Explorer Ridge (SER), part of the northern Juan de Fuca ridge system. We report radiogenic isotope (Pb, Sr, Nd, Hf) and geochemical data for twenty-four basalt whole-rock and glass samples collected from the length of the SER and from Explorer Deep, a rift to the north of the SER. Lavas from the SER form a north-south geochemical gradient, dominated by E-MORB at the northern axial high, and range from T-MORB to N-MORB towards the southern deepest part of the ridge. Linear relationships between incompatible element ratios and isotopic ratios in MORB along the ridge are consistent with mixing of magmas beneath the ridge to generate the geographic gradient from E- to N-MORB. The E-MORB have high Sr and Pb, and low Nd and Hf isotopic ratios, typical of enriched mantle that includes a FOZO or HIMU isotopic component. The West Valley and Endeavour segments of the northern Juan de Fuca ridge also include this isotopic component, but the proportion of the FOZO or HIMU component is more extreme in the SER basalts. The FOZO or HIMU component may be garnet-bearing peridotite, or a garnet pyroxenite embedded in peridotite. Recycled garnet pyroxenite better explains the very shallow SER axial high, high Nb/La and La/Sm, and the ;enriched; isotopic compositions.

  7. Historical volcanic eruptions in the Canary Islands, tephra composition, and insights into the crystal cargo of basaltic magmas (United States)

    Longpre, M. A.; Muller, J.; Beaudry, P.; Andronikides, A.; Felpeto, A.


    Since the 16th century, at least 13 volcanic eruptions have occurred in the Canary Islands that formed monogenetic cinder cones and lava flow fields: 2 on Lanzarote, 4 on Tenerife, 6 on La Palma, and 1 on the submarine flank of El Hierro. Here we present a comprehensive new dataset of tephra composition for all 13 eruptions, comprising major and trace element data for bulk rocks and matrix glasses, as well as vesicularity and crystallinity measurements. In addition, we compile available volcanological and petrological information for specific eruptions, including estimates of lava flow area and volume. All lapilli samples show a vesicularity of 40-50 vol% and a vesicle-free crystallinity (crystals ≥ 250 µm) of 5-15 vol%. Modal mineralogy varies significantly between samples, typically consisting of olivine ± clinopyroxene ± Fe-Ti oxide ± plagioclase ± amphibole in different proportions. All but 2 tephras have basanite-tephrite bulk rock compositions. Lapilli from vents of the AD 1730-1736 Timanfaya eruption, Lanzarote, largely are basaltic, whereas the AD 1798 Chahorra eruption, Tenerife, produced phonotephrite tephra. These results are in agreement with published bulk lava flow data. Unsurprisingly, glass compositions are more evolved than bulk rocks and MgOglass is weakly positively correlated to MgObulk (MgOglass = 0.30*MgObulk + 2.11, R2 = 0.54). Both bulk rocks and glasses show strikingly similar multi-element diagram patterns, with strong enrichment relative to the bulk-silicate Earth and marked positive Nb and Ta and negative Pb anomalies — typical for ocean island basalts. Glass/bulk rock elemental ratios reveal systematic differences between samples that relate to their mineralogy; for example, Lanzarote tephras that lack significant clinopyroxene and Fe-Ti oxide crystals have higher Scglass/Scbulk and Vglass/Vbulk than Tenerife, La Palma and El Hierro samples that typically contain these minerals. Among all elements, K and P display the greatest

  8. Chemical magnetization when determining Thellier paleointensity experiments in oceanic basalts (United States)

    Tselebrovskiy, Alexey; Maksimochkin, Valery


    The natural remanent magnetization (NRM) of oceanic basalts selected in the rift zones of the Mid-Atlantic Ridge (MAR) and the Red Sea has been explored. Laboratory simulation shows that the thermoremanent magnetization and chemical remanent magnetization (CRM) in oceanic basalts may be separated by using Tellier-Coe experiment. It was found that the rate of CRM destruction is about four times lower than the rate of the partial thermoremanent magnetization formation in Thellier cycles. The blocking temperatures spectrum of chemical component shifted toward higher temperatures in comparison with the spectrum of primary thermoremanent magnetization. It was revealed that the contribution of the chemical components in the NRM increases with the age of oceanic basalts determined with the analysis of the anomalous geomagnetic field (AGF) and spreading theory. CRM is less than 10% at the basalts aged 0.2 million years, less than 50% at basalts aged 0.35 million years, from 60 to 80% at basalts aged 1 million years [1]. Geomagnetic field paleointensity (Hpl) has been determined through the remanent magnetization of basalt samples of different ages related to Brunhes, Matuyama and Gauss periods of the geomagnetic field polarity. The value of the Hpl determined by basalts of the southern segment of MAR is ranged from 17.5 to 42.5 A/m, by the Reykjanes Ridge basalts — from 20.3 to 44 A/m, by the Bouvet Ridge basalts — from 21.7 to 34.1 A/m. VADM values calculated from these data are in good agreement with the international paleointensity database [2] and PISO-1500 model [3]. Literature 1. Maksimochkin V., Tselebrovskiy A., (2015) The influence of the chemical magnetization of oceanic basalts on determining the geomagnetic field paleointensity by the thellier method, moscow university physics bulletin, 70(6):566-576, 2. Perrin, M., E. Schnepp, and V. Shcherbakov (1998), Update of the paleointensity database, Eos Trans. AGU, 79, 198. 3. Channell JET, Xuan C, Hodell DA (2009

  9. Seawater sulfate reduction and sulfur isotope fractionation in basaltic systems: interaction of seawater with fayalite and magnetite at 200-3500C

    International Nuclear Information System (INIS)

    Shanks, W.C. III; Bischoff, J.L.; Rosenbauer, R.J.


    Sulfate reduction during seawater reaction with fayalite and with magnetite was rapid at 350 0 C, producing equilibrium assemblages of talc-pyrite-hematite-magnetite at low water/rock ratios and talc-pyrite-hematite-anhydrite at higher water/rock ratios. At 250 0 C, seawater reacting with fayalite produced detectable amounts of dissolved H 2 S. At 200 0 C, dissolved H 2 S was not detected, even after 219 days. Reaction stoichiometry indicates that sulfate reduction requires large amounts of H + , which, in subseafloor hydrothermal systems is provided by Mg metasomatism. Seawater contains sufficient Mg to supply all the H + necessary for quantitative reduction of seawater sulfate. Systematics of sulfur isotopes in the 250 and 350 0 C experiments indicate that isotopic equilibrium is reached and can be modeled as a Rayleigh distillation process. Isotopic composition of hydrothermally produced H 2 S in natural systems is strongly dependent upon the seawater/basalt ratio in the geothermal system, which controls the relative sulfide contributions from the two important sulfur sources, seawater sulfate and sulfide phases in basalt. Anhydrite precipitation during geothermal heating severely limits sulfate ingress into high temperature interaction zones. Quantitative sulfate reduction can thus be accomplished without producing strongly oxidized rocks and resultant sulfide sulfur isotope values represent a mixture of seawater and basaltic sulfur. (author)

  10. A constrained African craton source for the Cenozoic Numidian Flysch: Implications for the palaeogeography of the western Mediterranean basin (United States)

    Thomas, M. F. H.; Bodin, S.; Redfern, J.; Irving, D. H. B.


    The provenance of the Numidian Flysch in the western Mediterranean remains a controversial subject which hinders understanding of this regionally widespread depositional system. The Numidian Flysch is a deep marine formation dated as Oligocene to Miocene which outcrops throughout the Maghreb and into Italy. Evidence that is widely used for provenance analysis has not previously been reviewed within the context of the Maghrebian Flysch Basin as a whole. The structural location within the Alpine belt indicates deposition proximal to the African margin, while the uniformity of the Numidian Flysch petrofacies suggests a single cratonic source, in stark contrast to heterolithic and immature flysch formations from the north of the basin. Detrital zircon ages constrain a source region with Pan-African and Eburnian age rocks, unaffected by either Hercynian or Alpine tectonic events, which precludes the European basement blocks to the north of the basin. Palaeocurrent trends which suggest a northern source are unreliable given foreland basin analogues and observed structural complications. An African craton source remains the only viable option once these data are reviewed in their entirety, and the Numidian Flysch therefore represents a major Cenozoic drainage system on the North African margin. Deposition is concurrent with regional Atlas uplift phases, and coincidental with globally cooling climates and high sea levels. The Numidian Flysch is therefore interpreted to represent a highstand passive margin deposit, with timing of deposition controlled primarily by hinterland uplift and climatic fluctuations.

  11. Zircon (U-Th)/He Thermochronometric Constraints on Himalayan Thrust Belt Exhumation, Bedrock Weathering, and Cenozoic Seawater Chemistry (United States)

    Colleps, Cody L.; McKenzie, N. Ryan; Stockli, Daniel F.; Hughes, Nigel C.; Singh, Birendra P.; Webb, A. Alexander G.; Myrow, Paul M.; Planavsky, Noah J.; Horton, Brian K.


    Shifts in global seawater 187Os/188Os and 87Sr/86Sr are often utilized as proxies to track global weathering processes responsible for CO2 fluctuations in Earth history, particularly climatic cooling during the Cenozoic. It has been proposed, however, that these isotopic records instead reflect the weathering of chemically distinctive Himalayan lithologies exposed at the surface. We present new zircon (U-Th)/He thermochronometric and detrital zircon U-Pb geochronologic evidence from the Himalaya of northwest India to explore these contrasting interpretations concerning the driving mechanisms responsible for these seawater records. Our data demonstrate in-sequence southward thrust propagation with rapid exhumation of Lesser Himalayan strata enriched in labile 187Os and relatively less in radiogenic 87Sr at ˜16 Ma, which directly corresponds with coeval shifts in seawater 187Os/188Os and 87Sr/86Sr. Results presented here provide substantial evidence that the onset of exhumation of 187Os-enriched Lesser Himalayan strata could have significantly impacted the marine 187Os/188Os record at 16 Ma. These results support the hypothesis that regional weathering of isotopically unique source rocks can drive seawater records independently from shifts in global-scale weathering rates, hindering the utility of these records as reliable proxies to track global weathering processes and climate in deep geologic time.

  12. Geochemistry of the Potassic Basalts from the Bufumbira Volcanic ...

    African Journals Online (AJOL)

    The various basalts are low in SiO2 wt %, Al2O3 wt % and Na2O wt % but high in MgO wt %, TiO2 wt %, CaO wt %, K2O wt % with K2O/Na2O = 1.08 to 2.07. These are potassic belonging to the kamafugite series. Plots discriminate two geochemical trends corresponding to the picritic and clinopyroxene rich basalts.

  13. Radiolytic hydrogen production in the subseafloor basaltic aquifer

    Directory of Open Access Journals (Sweden)

    Mary E Dzaugis


    Full Text Available Hydrogen (H2 is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium (238U, 235U, thorium (232Th and potassium (40K. To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt concentrations (which can vary between eruptive events and post-emplacement alteration. In our samples, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may





    This paper proposes the potential of artificial neural network (ANN) system for estimating the bending strength values of the basalt fiber reinforced concrete pavements. Three main influential parameters; namely basalt fiber ratio, density and slump value of the fresh concrete were selected as input data. The model was trained, tested using 400 data sets which were the results of on-site experiment tests. ANN system results were also compared with the experimental test results. The research r...

  15. Archaean tectonic systems: A view from igneous rocks (United States)

    Moyen, Jean-François; Laurent, Oscar


    This work examines the global distribution of Archaean and modern igneous rock's compositions, without relying on preconceptions about the link between rock compositions and tectonic sites (in contrast with "geotectonic" diagrams). Rather, Archaean and modern geochemical patterns are interpreted and compared in terms of source and melting conditions. Mafic rocks on the modern Earth show a clear chemical separation between arc and non-arc rocks. This points to the first order difference between wet (arc) and dry (mid-ocean ridges and hotspots) mantle melting. Dry melts are further separated in depleted (MORB) and enriched (OIB) sources. This three-fold pattern is a clear image of the ridge/subduction/plume system that dominates modern tectonics. In contrast, Archaean mafic and ultramafic rocks are clustered in an intermediate position, between the three main modern types. This suggests that the Archaean mantle had lesser amounts of clearly depleted or enriched portions; that true subductions were rare; and that the distinction between oceanic plateaus and ridges may have been less significant. Modern granitic rocks dominantly belong to two groups: arc-related granitoids, petrologically connected to arc basalts; and collision granitoids, related to felsic sources. In contrast, the Archaean record is dominated by the TTG suite that derives from an alkali-rich mafic source (i.e. altered basalt). The geochemical diversity of the TTG suite points to a great range of melting depths, from ca. 5 to > 20 kbar. This reveals the absence of large sedimentary accumulations, again the paucity of modern-like arc situations, and the importance played by reworking of an earlier basaltic shell, in a range of settings (including some proto-subduction mechanisms). Nonetheless, granitoids in each individual region show a progressive transition towards more modern-looking associations of arc-like and peraluminous granites. Collectively, the geochemical evidence suggests an Archaean Earth

  16. Review of Y/OWI/TM-36: repository design performance in salt, granite, shale or basalt

    International Nuclear Information System (INIS)

    Talbot, R.; Nair, O.B.


    As part of the ongoing work by the Lawrence Livermore Laboratory to evaluate repository design performance, this memorandum presents a review of the preconceptual repository design described in Y/OWI/TM-36, Technical Support for GEIS: Radioactive Waste Isolation in Geologic Formations, April 1978. The purpose of this review is: to assess the adequacy of the design procedures and assumptions; to identify inappropriate or unsubstantiated design issues; to identify areas where additional numerical analyses may be required; and to develop data for inclusion in a reference repository design. The preconceptual repository design is presented in the form of 23 volumes of data base, analyses, and design layouts for four rock types: bedded salt, shale, granite and basalt. This memorandum reviews all four repository designs

  17. Insulation from basaltic stamp sand. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Williams, F. D.


    A Midwest Appropriate Technology Grant was awarded to determine the technical and economic feasibility of producing mineral-fiber insulation directly from extensive deposits of basaltic sand produced during former mining and milling operations in the Keweenaw Peninsula region of Michigan's Upper Peninsula. The amounts of local basaltic sands available and representative chemical compositions were determined. The variation of viscosity with temperature and chemical composition was estimated. Samples were melted and either pulled or blown into fiber. In all cases fiber could be made with a reasonable tensile strength to ensure usefulness. It was concluded that it was technically feasible to produce fibers from basaltic stamp sands of the Upper Peninsula of Michigan. A technical feasibility study using published data, a cost and design analysis of a basalt fiber production plant, a market survey of fiber needs, and an economic analysis for investing in a basalt fiber venture was undertaken. These studies concluded that the local production of basaltic insulation was both feasible and economically reasonable. It was suggested that the plant be located in a region of greater population density with lower utility costs. A representative one-third of these studies is included as appendices A, B, C, and D.

  18. Carbon Sequestration in Olivine and Basalt Powder Packed Beds. (United States)

    Xiong, Wei; Wells, Rachel K; Giammar, Daniel E


    Fractures and pores in basalt could provide substantial pore volume and surface area of reactive minerals for carbonate mineral formation in geologic carbon sequestration. In many fractures solute transport will be limited to diffusion, and opposing chemical gradients that form as a result of concentration differences can lead to spatial distribution of silicate mineral dissolution and carbonate mineral precipitation. Glass tubes packed with grains of olivine or basalt with different grain sizes and compositions were used to explore the identity and spatial distribution of carbonate minerals that form in dead-end one-dimensional diffusion-limited zones that are connected to a larger reservoir of water in equilibrium with 100 bar CO 2 at 100 °C. Magnesite formed in experiments with olivine, and Mg- and Ca-bearing siderite formed in experiments with flood basalt. The spatial distribution of carbonates varied between powder packed beds with different powder sizes. Packed beds of basalt powder with large specific surface areas sequestered more carbon per unit basalt mass than powder with low surface area. The spatial location and extent of carbonate mineral formation can influence the overall ability of fractured basalt to sequester carbon.

  19. Petrogenesis of Cenozoic, alkalic volcanic lineages at Mount Morning, West Antarctica and their entrained lithospheric mantle xenoliths: Lithospheric versus asthenospheric mantle sources (United States)

    Martin, Adam P.; Cooper, Alan F.; Price, Richard C.


    Two volcanic lineages are identified at Mount Morning, a Cenozoic to recent, eruptive centre in the Ross Sea, West Antarctica, which is part of the McMurdo Volcanic Group. Both the older (at least 18.7-11.4 Ma), mildly alkalic, nepheline- or quartz-normative Mason Spur Lineage, and the younger (at least 6-0.02 Ma), nepheline normative, strongly alkalic Riviera Ridge Lineage evolved by fractional crystallization from nominally anhydrous (Zealandia and eastern Australia share common chemical and isotopic source characteristics and they have been argued to collectively constitute a single diffuse alkaline magmatic province (DAMP). Source characteristic similarities suggest DAMP volcanic rocks inherit at least some of their trace element and isotopic characteristics from the lithospheric mantle. Super-chondritic Nb/Ta values measured in some SCLM xenoliths and volcanic rocks at Mount Morning, and in volcanic rocks across the DAMP, can be explained by addition of ⩽5 wt% carbonatite to the source. The DAMP SCLM is a significant Nb reservoir that offers an explanation for the Nb paradox.

  20. Geologic map of the Beacon Rock quadrangle, Skamania County, Washington (United States)

    Evarts, Russell C.; Fleck, Robert J.


    The Beacon Rock 7.5′ quadrangle is located approximately 50 km east of Portland, Oregon, on the north side of the Columbia River Gorge, a scenic canyon carved through the axis of the Cascade Range by the Columbia River. Although approximately 75,000 people live within the gorge, much of the region remains little developed and is encompassed by the 292,500-acre Columbia River Gorge National Scenic Area, managed by a consortium of government agencies “to pro­tect and provide for the enhancement of the scenic, cultural, recreational and natural resources of the Gorge and to protect and support the economy of the Columbia River Gorge area.” As the only low-elevation corridor through the Cascade Range, the gorge is a critical regional transportation and utilities corridor (Wang and Chaker, 2004). Major state and national highways and rail lines run along both shores of the Columbia River, which also provides important water access to ports in the agricultural interior of the Pacific Northwest. Transmission lines carry power from hydroelectric facilities in the gorge and farther east to the growing urban areas of western Oregon and Washington, and natural-gas pipelines transect the corridor (Wang and Chaker, 2004). These lifelines are highly vulnerable to disruption by earthquakes, landslides, and floods. A major purpose of the work described here is to identify and map geologic hazards, such as faults and landslide-prone areas, to provide more accurate assessments of the risks associated with these features.The steep canyon walls of the map area reveal exten­sive outcrops of Miocene flood-basalt flows of the Columbia River Basalt Group capped by fluvial deposits of the ances­tral Columbia River, Pliocene lavas erupted from the axis of the Cascade arc to the east, and volcanic rocks erupted from numerous local vents. The Columbia River Basalt Group unconformably rests on a sequence of late Oligocene and early Miocene rocks of the ancestral Cascade volcanic arc

  1. Controlled sample program publication No. 1: characterization of rock samples

    International Nuclear Information System (INIS)

    Ames, L.L.


    A description is presented of the methodology used and the geologic parameters measured on several rocks which are being used in round-robin laboratory and nuclide adsorption methodology experiments. Presently investigators from various laboratories are determining nuclide distribution coefficients utilizing numerous experimental techniques. Unfortunately, it appears that often the resultant data are dependent not only on the type of groundwater and rock utilized, but also on the experimentor or method used. The Controlled Sample Program is a WISAP (Waste Isolation Safety Assessment Program) attempt to resolve the apparent method and dependencies and to identify individual experimenter's bias. The rock samples characterized in an interlaboratory Kd methodology comparison program include Westerly granite, Argillaceous shale, Oolitic limestone, Sentinel Gap basalt, Conasauga shale, Climax Stock granite, anhydrite, Magenta dolomite and Culebra dolomite. Techniques used in the characterization include whole rock chemical analysis, X-ray diffraction, optical examination, electron microprobe elemental mapping, and chemical analysis of specific mineral phases. Surface areas were determined by the B.E.T. and ethylene glycol sorption methods. Cation exchange capacities were determined with 85 Sr, but were of questionable value for the high calcium rocks. A quantitative mineralogy was also estimated for each rock. Characteristics which have the potential of strongly affecting radionuclide Kd values such as the presence of sulfides, water-soluble, pH-buffering carbonates, glass, and ferrous iron were listed for each rock sample

  2. Vapor segregation and loss in basaltic melts (United States)

    Edmonds, M.; Gerlach, T.M.


    Measurements of volcanic gases at Pu'u'O??'o??, Kilauea Volcano, Hawai'i, reveal distinct degassing regimes with respect to vapor segregation and loss during effusive activity in 2004-2005. Three styles of vapor loss are distinguished by the chemical character of the emitted volcanic gases, measured by open path Fourier transform infrared spectroscopy: 1 persistent continuous gas emission, 2 gas piston events, and 3 lava spattering. Persistent continuous gas emission is associated with magma ascent and degassing beneath the crater vents, then eruption of the degassed magma from flank vents. Gas piston events are the result of static gas accumulation at depths of 400-900 m beneath Pu'u'O??'o??. A CO2-rich gas slug travels up the conduit at a few meters per second, displacing magma as it expands. Lava spattering occurs due to dynamic bubble coalescence in a column of relatively stagnant magma. The Large gas bubbles are H2O rich and are generated by open-system degassing at depths of gas accumulation and dynamic bubble coalescence are both manifestations of vapor segregation in basaltic melts, but their implications differ. Accumulation and segregation of CO2-rich vapor at depth does not deplete the melt of H2O (required to drive lava fountains near to the surface) and therefore gas piston events can occur interspersed with lava fountaining activity. Lava spattering, however, efficiently strips H2O-rich vapor from magma beneath the crater vents; the magma must then erupt effusively from vents on the flank of the cone. ?? 2007 The Geological Society of America.

  3. Basalt Waste Isolation Project Reclamation Support Project:

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, C.A.; Rickard, W.H. Jr.; Cadoret, N.A.


    The Basalt Waste Isolation Project (BWIP) Reclamation Support Project began in the spring of 1988 by categorizing sites distributed during operations of the BWIP into those requiring revegetation and those to be abandoned or transferred to other programs. The Pacific Northwest Laboratory's role in this project was to develop plans for reestablishing native vegetation on the first category of sites, to monitor the implementation of these plans, to evaluate the effectiveness of these efforts, and to identify remediation methods where necessary. The Reclamation Support Project focused on three major areas: geologic hydrologic boreholes, the Exploratory Shaft Facility (ESF), and the Near-Surface Test Facility (NSTF). A number of BWIP reclamation sites seeded between 1989 and 1990 were found to be far below reclamation objectives. These sites were remediated in 1991 using various seedbed treatments designed to rectify problems with water-holding capacity, herbicide activity, surficial crust formation, and nutrient imbalances. Remediation was conducted during November and early December 1991. Sites were examined on a monthly basis thereafter to evaluate plant growth responses to these treatments. At all remediation sites early plant growth responses to these treatments. At all remediation sites, early plant growth far exceeded any previously obtained using other methods and seedbed treatments. Seeded plants did best where amendments consisted of soil-plus-compost or fertilizer-only. Vegetation growth on Gable Mountain was less than that found on other areas nearby, but this difference is attributed primarily to the site's altitude and north-facing orientation.


    Directory of Open Access Journals (Sweden)



    Full Text Available We report the findings of two proboscideans from a sedimentary intercalation within the Central Eritrea Tertiary Trap basalt succession. These intertrappean sediments can be traced continuously between Tera’emni and Adi Quala in the Mendefera region, and are interbedded between the underlying Asmara/Aiba-Alaji basalts and the overlying Adi Ugri basalt. This intercalation is up to 50 m thick and consists of a predominant intensely pedogenized red, green and gray mudstone and siltstone with subordinate channelized pebbly sandstone. The newly discovered mammal remains come from the coarse-grained deposits in the Mai Gobro section.  Available radiometric datings of the host volcanic rocks constrain the age of the fossils between 24.6 and 22.1 Ma, i.e. at the transition between the Oligocene and the Miocene. The fossil vertebrate remains from Mai Gobro represent two proboscidean families, Deinotheriidae and Gomphotheriidae. The morphological grade of the two Mai Gobro proboscideans would suggest a more derived stage than that of representatives of the same families known from other Oligocene African sited (e.g. Chilga, Ethiopia, suggesting a possible Oligo-Miocene age. 

  5. Investigating lava-substrate interactions through flow experiments with syrup, wax, and molten basalt (United States)

    Rumpf, M. E.; Lev, E.


    Among the many factors influencing the complex process of lava flow emplacement, the interaction with the substrate onto which flow is emplaced plays a central role. Lava flows are rarely emplaced onto smooth or regular surfaces. For example, at Kīlauea Volcano, Hawai'i, lava flows regularly flow over solid rock, vegetation, basaltic or silica sand, and man-made materials, including asphalt and concrete. In situ studies of lava-substrate interactions are inherently difficult, and often dangerous, to carry-out, requiring the design of controllable laboratory experiments. We investigate the effects of substrate grain size, cohesion, and roughness on flow mobility and morphology through a series of flow experiments using analog materials and molten basalt. We have developed a series of experiments that allow for adjustable substrate parameters and analyze their effects on lava flow emplacement. The first set of experiments are performed at the Fluids Mechanics Laboratory at the Lamont-Doherty Earth Observatory and focus on two analog materials: polyethylene glycol (PEG), a commercially available wax, and corn syrup. The fluids were each extruded onto a series of scaled substrate beds to replicate the emplacement of lava in a natural environment. Preliminary experiments demonstrated that irregular topography, particularly topography with a height amplitude similar to that of the flow itself, can affect flow morphology, width, and velocity by acting as local barriers or culverts to the fluid. This is expected from observations of fluid flow in natural environments. A follow-up set of experiments will be conducted in Fall 2015 at the Syracuse University (SU) Lava Project Lab. In this set, we will pour molten basalt directly onto a series of substrates representing natural environments found on the Earth and other rocky bodies in the Solar System. These experiments will allow for analysis of the effects of basaltic composition and high temperatures on lava-substrate heat

  6. Numerical modeling of rock stresses within a basaltic nuclear waste repository. Final report

    International Nuclear Information System (INIS)

    Hardy, M.P.; Hocking, G.


    The modeling undertaken during this project incorporated a wide range of problems that impact the design of the waste repository. Interaction of groundwater, heat and stress were considered on a regional scale, whereas on the room and canister scale thermo-mechanical analyses were undertaken. In the Phase II report, preliminary guidelines for waste densities were established based primarily on short-term stress criteria required to maintain stability during the retrievability period. Additional analyses are required to evaluate the effect of joints, borehole linings, room support and ventilation on these preliminary waste loading densities. The regional analyses did not indicate any adverse effect that could control the allowable waste loading densities. However, further refinements of geologic structure, hydrologic models, seismicity and possible induced seismicity are required before firm estimates of the loading densities can be made

  7. An attempt to correct for the fading in million year old basaltic rocks

    DEFF Research Database (Denmark)

    Morthekai, P.; Jain, Mayank; Cunha, Pedro P.


    The use of feldspar for luminescence dating has been restricted because of anomalous fad-ing. This has made its application to several important geological problems such as volcanic terrains difficult. Presently, two correction procedures are used to correct for anomalous fading. The present study...

  8. Radiometric survey and preliminary phosphorus geologic reconnaissance of some Cenozoic basins, in Chile

    International Nuclear Information System (INIS)

    Rojo L, M.


    A geological radiometric survey was conducted on some Cenozoic basins located in the 2nd and 3nd Region of Chile. The purpose was to discover some phosphatic indications related to oolitic (''Mejillones'' type) or conglomerate ('' Bahia Inglesa'' type) model. the results are indicated and, some geological characteristics of the Araujo Basin are presented. The available information related to geological conditions of Cenozoic marine sedimentation in coastal platform, would suggest that the best possibility to find phosphatic resources is located between parallels 23 0 and 31 0 So. Lat. (author)

  9. The Cenozoic geological evolution of the Central and Northern North Sea based on seismic sequence stratigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Jordt, Henrik


    This thesis represents scientific results from seismic sequence stratigraphic investigations. These investigations and results are integrated into an ongoing mineralogical study of the Cenozoic deposits. the main results from this mineralogical study are presented and discussed. The seismic investigations have provided boundary conditions for a forward modelling study of the Cenozoic depositional history. Results from the forward modelling are presented as they emphasise the influence of tectonics on sequence development. The tectonic motions described were important for the formation of the large oil and gas fields in the North Sea.

  10. Rocks Can Wow? Yes, Rocks Can Wow! (United States)

    Hardman, Sally; Luke, Sue


    Rocks and fossils appear in the National Curriculum of England science programmes of study for children in year 3 (ages 7-8). A frequently asked question is "How do you make the classification of rocks engaging?" In response to this request from a school, a set of interactive activities was designed and organised by tutors and students…

  11. The rock melting approach to drilling

    Energy Technology Data Exchange (ETDEWEB)

    Cort, G.E.; Goff, S.J.; Rowley, J.C.; Neudecker, J.W. Jr.; Dreesen, D.S.; Winchester, W.


    During the early and mid-1970`s the Los Alamos National Laboratory demonstrated practical applications of drilling and coring using an electrically-heated graphite, tungsten, or molybdenum penetrator that melts a hole as it is slowly pushed through the rock or soil. The molten material consolidates into a rugged glass lining that prevents hole collapse; minimizes the potential for cross-flow, lost circulation, or the release of hazardous materials without casing operations; and produces no cuttings in porous or low density (<1.7 g/cc) formations. Because there are no drilling fluids required, the rock melting approach reduces waste handling, treatment and disposal. Drilling by rock melting has been demonstrated to depths up to 30 m in caliche, clay, alluvium, cobbles, sand, basalt, granite, and other materials. Penetrating large cobbles without debris removal was achieved by thermal stress fracturing and lateral extrusion of portions of the rock melt into the resulting cracks. Both horizontal and vertical holes in a variety of diameters were drilled in these materials using modular, self-contained field units that operate in remote areas. Because the penetrator does not need to rotate, steering by several simple approaches is considered quite feasible. Melting is ideal for obtaining core samples in alluvium and other poorly consolidated soils since the formed-in-place glass liner stabilizes the hole, encapsulates volatile or hazardous material, and recovers an undisturbed core. Because of the relatively low thermal conductivity of rock and soil materials, the heat-affected zone beyond the melt layer is very small, <1 inch thick. Los Alamos has begun to update the technology and this paper will report on the current status of applications and designs for improved drills.

  12. Time-dependent deformation at elevated temperatures in basalt from El Hierro, Stromboli and Teide volcanoes (United States)

    Benson, P. M.; Fahrner, D.; Harnett, C. E.; Fazio, M.


    Time dependent deformation describes the process whereby brittle materials deform at a stress level below their short-term material strength (Ss), but over an extended time frame. Although generally well understood in engineering (where it is known as static fatigue or "creep"), knowledge of how rocks creep and fail has wide ramifications in areas as diverse as mine tunnel supports and the long term stability of critically loaded rock slopes. A particular hazard relates to the instability of volcano flanks. A large number of flank collapses are known such as Stromboli (Aeolian islands), Teide, and El Hierro (Canary Islands). Collapses on volcanic islands are especially complex as they necessarily involve the combination of active tectonics, heat, and fluids. Not only does the volcanic system generate stresses that reach close to the failure strength of the rocks involved, but when combined with active pore fluid the process of stress corrosion allows the rock mass to deform and creep at stresses far lower than Ss. Despite the obvious geological hazard that edifice failure poses, the phenomenon of creep in volcanic rocks at elevated temperatures has yet to be thoroughly investigated in a well controlled laboratory setting. We present new data using rocks taken from Stromboli, El Heirro and Teide volcanoes in order to better understand the interplay between the fundamental rock mechanics of these basalts and the effects of elevated temperature fluids (activating stress corrosion mechanisms). Experiments were conducted over short (30-60 minute) and long (8-10 hour) time scales. For this, we use the method of Heap et al., (2011) to impose a constant stress (creep) domain deformation monitored via non-contact axial displacement transducers. This is achieved via a conventional triaxial cell to impose shallow conditions of pressure (<25 MPa) and temperature (<200 °C), and equipped with a 3D laboratory seismicity array (known as acoustic emission, AE) to monitor the micro

  13. Petrogenesis of the western highlands of the moon - Evidence from a diverse group of whitlockite-rich rocks from the Fra Mauro formation (United States)

    Snyder, Gregory A.; Taylor, Lawrence A.; Liu, Yun-Gang; Schmitt, Roman A.


    A group of KREEPy basalts has been discovered in Apollo 14 soils. These samples exhibit similarities to both HA and VHK basalts, albeit with much higher REE abundances, and contain up to 2 vol pct whitlockite and can be explained by assimilation of a K-, REE- and P-rich fluids by an original HA or VHK basalt. This KREEP component could have been produced late in the evolution of the lunar magma ocean and is similar in composition to QMD at Apollo 14. Two rocks have trace element compositions that are representative of actual KREEP. One of the samples appears to be petrographically pristine and could represent an actual KREEP basalt rock. Five subophitic high-Al basalts represent sampling of either a slowly cooled impact melt sheet or, more likely, the same basalt flow. Two 'quasi-pristine' highland rocks confirm the postulate of a connection between KREEP and the alkali suite. A newly discovered alkali anorthosite is a plagioclase cumulate with about 15 percent trapped KREEPy liquid.

  14. Combined Li-He isotopes in Iceland and Jan Mayen basalts and constraints on the nature of the North Atlantic mantle (United States)

    Magna, T.; Wiechert, U.; Stuart, F. M.; Halliday, A. N.; Harrison, D.


    Lithium (Li) isotopes are thought to provide a powerful proxy for the recycling of crustal material, affected by low temperature alteration, through the mantle. We present Li isotope compositions for basaltic volcanic rocks from Hengill, Iceland, and Jan Mayen in order to examine possible links between ocean island volcanism and recycled oceanic crust and to address recent suggestions that mantle 3He/ 4He is also related to recycling of ancient slabs. Basaltic glasses spanning a range of chemical enrichment from the Hengill fissure system define an inverse correlation between δ 7Li (3.8-6.9‰) and 3He/ 4He (12-20 RA). The high- 3He/ 4He basalts have low δ 18O as well as excess Eu and high Nb/U, but carry no Li isotope evidence of being the product of recycling of altered slab or wedge material. In fact, there is no clear correlation between Li or He isotopes on the one hand and any of the other fingerprints of recycled slab components. The low- 3He/ 4He samples do have elevated Nb/U, Sr/Nd, positive Eu anomalies and high δ 7Li (˜6.9‰), providing evidence of a cumulate-enriched source that could be part of an ancient altered ocean floor slab. Basalts from Jan Mayen are characterized by large degrees of enrichment in incompatible trace elements typical of EM-like basalts but have homogeneous δ 7Li typical of depleted mantle (3.9-4.7‰) providing evidence for a third mantle source in the North Atlantic. It appears that oceanic basalts can display a wide range in isotope and trace element compositions associated with recycled components whilst exhibiting no sign of modern surface-altered slab or wedge material from the Li isotope composition.

  15. Rock Slope Design Criteria (United States)


    Based on the stratigraphy and the type of slope stability problems, the flat lying, Paleozoic age, sedimentary : rocks of Ohio were divided into three design units: 1) competent rock design unit consisting of sandstones, limestones, : and siltstones ...

  16. Rocks in Our Pockets (United States)

    Plummer, Donna; Kuhlman, Wilma


    To introduce students to rocks and their characteristics, teacher can begin rock units with the activities described in this article. Students need the ability to make simple observations using their senses and simple tools.

  17. Rock slope design guide. (United States)


    This Manual is intended to provide guidance for the design of rock cut slopes, rockfall catchment, and : rockfall controls. Recommendations presented in this manual are based on research presented in Shakoor : and Admassu (2010) entitled Rock Slop...

  18. Ore-forming adakitic porphyry produced by fractional crystallization of oxidized basaltic magmas in a subcrustal chamber (Jiamate, East Junggar, NW China) (United States)

    Hong, Tao; Xu, Xing-Wang; Gao, Jun; Peters, Stephen; Zhang, Di; Jielili, Reyaniguli; Xiang, Peng; Li, Hao; Wu, Chu; You, Jun; Liu, Jie; Ke, Qiang


    ore-bearing adakitic intrusions in the KPCB and the adakitic Jiamate Complex intrusions were both probably generated from the same basaltic parental magmas through fractional crystallization. In addition, characteristics of the layered, magnetite-bearing, oxidized, basaltic Jiamate Complex intrusive rocks indicate that they are likely to be the parental arc magmas for the nearby porphyry Cu deposits. This conclusion is based on new interpretations of the regional and local geology, on interpretation of new geochemical analysis, new stable isotope analysis, new geothermobarometry, and new zircon age dating as well as other techniques and interpretations.

  19. The Formation of Carbonate Minerals and the Mobility of Heavy Metals during Water-CO2-Mafic Rock Interactions

    DEFF Research Database (Denmark)

    Olsson, Jonas

    the basaltic host rock and liberates cations. Ideally, the cations react with the dissolved CO2 and form long time stable carbonate minerals. However, dissolution of the basaltic rock can lead to mobility of toxic metals, which is a potential threat to groundwater supplies and surface waters. Besides carbonate...... with the process of carbonation, and (2) they can form a passivating layer, which inhibit dissolution of the basaltic material and slow down the carbonation process. The purpose of this thesis was to identify formation products, relevant to CarbFix, and assess their ability to immobilize toxic metals released from...... are consistent with values of controlled laboratory experiments from the literature for Ba, Cd, Co, Cu, Mg, Mn, Na, Ni, Sr and Zn. The calcium carbonates also scavenge other elements, including rare earth elements (REE) and the toxic metals As and Pb. This and the next study can be considered natural analogues...

  20. Geochronology of La Tinta Upper Proterozoic sedimentary rocks, Argentina

    International Nuclear Information System (INIS)

    Cingolani, C.A.; Bonhomme, M.G.


    Olavarria-Sierras Bayas, Barker-San Manuel and Balcarce-Mar del Plata fine-grained sedimentary rocks from La Tinta Formation, the pre-Cenozoic cover of the Tandilia region, were studied using the Rb-Sr and K-Ar geochronology. The mineralogical study of the fine fraction has shown that only the Olavarria-Sierras Bayas area presents suitable material comprising typical sedimentary clays, affected only by diagenetic processes. Two Rb-Sr isochrons were obtained from Olavarria-Sierras Bayas rocks. They show: (1) an age of 769 +- 12 Ma with ( 87 Sr/ 86 Sr) 0 = 0.7121 +- 0.0005, for Aust Quarry rocks; and (2) an age of 723 +- 21 Ma with ( 87 Sr/ 86 Sr) 0 = 0.7171 +- 0.0012 for Cerro Negro and Losa Quarries rocks. Considering the above-mentioned isochron data and the mineralogy of the clays studied, the conclusion is drawn that the ages obtained reflect the isotopic setting of a late diagenetic process, dated back to nearly 720 Ma. K-Ar data also support the Rb-Sr isochrons and the late diagenetic clay origin. The lower section of La Tinta sequence in the Sierras Bayas area must then be considered as Upper Proterozoic in age. These new data support the recently reported stratigraphical divisions and ages. (Auth.)

  1. Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars (United States)

    Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.


    A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

  2. Simulated high-level waste-basalt interaction experiments. Annual progress report, October 1, 1977--September 30, 1978

    International Nuclear Information System (INIS)

    Scheetz, B.E.; Smith, D.K.; Barnes, M.W.; Komarneni, S.; Stull, L.M.; Smith, C.A.


    Reconnaissance experiments suggested that the observed reactivity of calcine and glass as 300 0 C would be anticipated at lower temperatures but only after longer times of hydrothermal treatment. Long-duration experiments at 100 0 and 300 0 C were initiated to determine the time dependence of the alterations at lower temperatures. The reconnaissance experiments also suggested that equilibrium conditions were not yet achieved in these closed system experiments. Glass was observed to alter readily with the formation of acmite-augite pyroxene; a uranyl silicate, weeksite; and a rare-earth slicate-phosphate hydroxyapatite. Nearly all of the B, ca. 70% of the Mo and ca. 50% of the Na in the original glass were dissolved. A simulated reduced SURF (spent unreprocessed fuel) was utilized in hydrothermal experiments. Analyses of the solutions confirmed that soluble fission products phases were leached from the UO 2 matrix and all of the alkali metals were leached from the SURF. In the presence of basalt, however, the released alkalis react with aluminosilicates and are removed from solution. Individual phases believed to be present in SURF have been hydrothermally treated, with the reference basalts and with major primary and secondary minerals. Cs(OH), Cs 2 MoO 4 and Cs 2 U 2 O 7 were used as potential cesium phases. In some cases as much as 99.9% of the cesium can be removed from solution by interacting with the rocks and minerals to form pollucite. The interaction of strontium zirconate under hydrothermal conditions with the above rock and basalt minerals indicates that in all cases 99.9% of the available strontium is retained in the strontium zirconate or as alteration products. 11 figures, 8 tables

  3. Drainage development and incision rates in an Upper Pleistocene Basalt-Limestone Boundary Channel: The Sa'ar Stream, Golan Heights, Israel (United States)

    Shtober-Zisu, N.; Inbar, M.; Mor, D.; Jicha, B. R.; Singer, B. S.


    Long-term fluvial incision processes and corresponding geomorphic evolution are difficult to quantify, especially in complex systems affected by lithological and tectonic factors. Volcanic landscapes offer the most appropriate environment for the study of landscape evolution, as there is a clear starting time of formation and the lithology is homogenous. In the present study we aim to: (1) analyse the interplay of construction and incision processes throughout eruptive activity; (2) study fluvial erosion processes; (3) analyse sedimentary and volcanic lithological responses to channel erosion; and (4) calculate the incision rates in young basaltic bedrock. We have integrated existing and new 40Ar/39Ar ages of lava flows with estimates of channel geometry and tectonic activity, and considered process geomorphology conce