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Sample records for archean metavolcanic rocks

  1. Geochemistry of metavolcanic rocks in the Archean Greenstone Belt of Identidade, SE Para, Brazil

    International Nuclear Information System (INIS)

    Souza, Zorano S.

    1995-01-01

    The paper discusses the geochemistry of the ultramafic and mafic volcanic rocks of the Identidade belt (IDB), in order to present hypothesis about their possible sources and magmatic evolution. The chemical data were obtained by ICP method. The analytical errors are less then 5% for major elements, less than 10% for the minor ones, and around 5% for trace elements. Save additional data from the meta ultramafic rocks of the Seringa belt, situated 100 km to the west of the IDB, were also considered. The XLFRAC program was employed for fractional crystallization modelling of major elements. For trace element modelling the equations of fractional crystallization and equilibrium partial melting were applied, using an unpublished program written in Pascal. 10 figs. 8 tabs

  2. Sr–Nd isotopic compositions of Paleoproterozoic metavolcanic rocks from the southern Ashanti volcanic belt, Ghana

    OpenAIRE

    Dampare, Samuel; Shibata, Tsugio; Asiedu, Daniel; Okano, Osamu; Manu, Johnson; Sakyi, Patrick

    2009-01-01

    Neodymium (Nd) and strontium (Sr) isotopic data are presented for Paleoproterozoic metavolcanic rocks in the southern part of the Ashanti volcanic belt of Ghana. The metavolcanic rocks are predominantly basalts/basaltic andesites and andesites with minor dacites. Two types of basalts/basaltic andesites (B/A), Type I and Type II, have been identified. The Type I B/A are stratigraphically overlain by the Type II B/A, followed by the andesites and the dacites. The analyzed volcanic rocks commonl...

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

    Directory of Open Access Journals (Sweden)

    Ibrahim H. Khalifa

    2011-07-01

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

  4. 3.3 Ga SHRIMP U-Pb zircon age of a felsic metavolcanic rock from the Mundo Novo greenstone belt in the São Francisco craton, Bahia (NE Brazil)

    Science.gov (United States)

    Peucat, J. J.; Mascarenhas, J. F.; Barbosa, J. S. F.; de Souza, S. L.; Marinho, M. M.; Fanning, C. M.; Leite, C. M. M.

    2002-07-01

    Felsic metavolcanics associated with supracrustal rocks provide U-Pb zircon and Sm-Nd TDM ages of approximately 3.3 Ga, which establish an Archean age of the Mundo Novo greenstone belt. A granodioritic gneiss from the Mairi complex, located on the eastern boundary of the Mundo Novo greenstone belt, exhibits a zircon evaporation minimum age of 3.04 Ga and a Nd model age of 3.2 Ga. These results constrain the occurrence of at least three major geological units in this area: the Archean Mundo Novo greenstone belt, the Archean Mairi gneisses, and the adjoining Paleoproterozoic (<2.1 Ga) Jacobina sedimentary basin. The Jacobina basin follows the same trend as the Archean structure, extending southward to the Contendas-Mirante belt, in which a similar Archean-Paleoproterozoic association appears. We postulate that during the Paleoproterozoic in the eastern margin of the Gavião block, these Archean greenstone belts constituted a zone of weakness along which a late-stage orogenic sedimentary basin developed.

  5. Alteration of submarine volcanic rocks in oxygenated Archean oceans

    Science.gov (United States)

    Ohmoto, H.; Bevacqua, D.; Watanabe, Y.

    2009-12-01

    Most submarine volcanic rocks, including basalts in diverging plate boundaries and andesites/dacites in converging plate boundaries, have been altered by low-temperature seawater and/or hydrothermal fluids (up to ~400°C) under deep oceans; the hydrothermal fluids evolved from shallow/deep circulations of seawater through the underlying hot igneous rocks. Volcanogenic massive sulfide deposits (VMSDs) and banded iron formations (BIFs) were formed by mixing of submarine hydrothermal fluids with local seawater. Therefore, the behaviors of various elements, especially of redox-sensitive elements, in altered submarine volcanic rocks, VMSDs and BIFs can be used to decipher the chemical evolution of the oceans and atmosphere. We have investigated the mineralogy and geochemistry of >500 samples of basalts from a 260m-long drill core section of Hole #1 of the Archean Biosphere Drilling Project (ABDP #1) in the Pilbara Craton, Western Australia. The core section is comprised of ~160 m thick Marble Bar Chert/Jasper Unit (3.46 Ga) and underlying, inter-bedded, and overlying submarine basalts. Losses/gains of 65 elements were quantitatively evaluated on the basis of their concentration ratios against the least mobile elements (Ti, Zr and Nb). We have recognized that mineralogical and geochemical characteristics of many of these samples are essentially the same as those of hydrothermally-altered modern submarine basalts and also those of altered volcanic rocks that underlie Phanerozoic VMSDs. The similarities include, but are not restricted to: (1) the alteration mineralogy (chlorite ± sericite ± pyrophyllite ± carbonates ± hematite ± pyrite ± rutile); (2) the characteristics of whole-rock δ18O and δ34S values; (3) the ranges of depletion and enrichment of Si, Al, Mg, Ca, K, Na, Fe, Mn, and P; (4) the enrichment of Ba (as sulfate); (5) the increases in Fe3+/Fe2+ ratios; (6) the enrichment of U; (7) the depletion of Cr; and (8) the negative Ce anomalies. Literature data

  6. Evaluation of early Archean volcaniclastic and volcanic flow rocks as possible sites for carbonaceous fossil microbes.

    Science.gov (United States)

    Walsh, Maud M

    2004-01-01

    Sedimentary rocks have traditionally been the focus of the search for Archean microfossils; the Earth's oldest fossil bacteria are associated with carbonaceous matter in sedimentary cherts in greenstone belts in the eastern Pilbara block of Western Australia and Barberton greenstone belt of South Africa. Reports of possible fossils in a martian meteorite composed of igneous rock and the discovery of modern bacteria associated with basalts have stimulated a new look at Archean volcanic rocks as possible sites for fossil microbes. This study examines silicified volcaniclastic rocks, near-surface altered volcanic flow rocks, and associated stromatolite- like structures from the Archean Barberton greenstone belt to evaluate their potential for the preservation of carbonaceous fossils. Detrital carbonaceous particles are widely admixed with current-deposited debris. Carbonaceous matter is also present in altered volcanic flow rocks as sparse particles in silica veins that appear to be fed by overlying carbonaceous chert layers. Neither microfossils nor mat-like material was identified in the altered volcanic rocks or adjacent stromatolite-like structures. Ancient volcanic flow and volcaniclastic rocks are not promising sites for carbonaceous fossil preservation.

  7. Stages of material transformations of Archean-Proterozoic rocks (Central-Karelian domain)

    International Nuclear Information System (INIS)

    Vinogradov, V.I.; Buyakajte, M.I.; Kolodyazhnyj, S.Yu.; Leonov, M.G.; Orlov, S.Yu.

    2001-01-01

    The age of the Archean-Proterozoic rocks from the south-east part of the Central-Karelian domain was determined by the method of Rb-Sr dating. It was ascertained that the age of the least tectonized rocks of granite-greenstone Archean foundation makes up 2800±70 mln. years at initial strontium isotopic ratio of 0.7022±0.0007. Gneisses of mainly plagiogranite composition, their age 1930±118 mln. years and strontium isotopic ratio 0.7170±0.0026, constitute the second group of the rocks. It is shown that isotopic age defined for the two groups of rocks agrees well with major geological events on the Baltic shield and planet as a whole [ru

  8. Coexistence of enriched and modern-like 142Nd signatures in Archean igneous rocks of the eastern Kaapvaal Craton, southern Africa

    Science.gov (United States)

    Schneider, Kathrin P.; Hoffmann, J. Elis; Boyet, Maud; Münker, Carsten; Kröner, Alfred

    2018-04-01

    The short-lived 146Sm-142Nd isotope system is an important tool for tracing Hadean crust-mantle differentiation processes and constraining their imprint on much younger rocks from Archean cratons. We report the first comprehensive set of high-precision 142Nd analyses for granitoids and amphibolites of the Ancient Gneiss Complex (AGC; Swaziland) and the oldest metavolcanic units of the Barberton Greenstone Belt (BGB; South Africa). The investigated samples span an age range from 3.66 Ga to 3.22 Ga and are representative of major geological units of the AGC and the lower Onverwacht Group of the BGB. Measured samples yielded μ142Nd values in the range from -8 ppm to +3 ppm relative to the JNdi-1 terrestrial standard, with typical errors smaller than 4.4 ppm. The distribution of the μ142Nd values for these 17 measured samples is bimodal with ten samples showing a tendency towards slightly negative μ142Nd anomalies, whereas seven samples have 142Nd similar to the terrestrial reference. The only confidently resolvable μ142Nd anomalies were found in a 3.44 Ga Ngwane Gneiss sample and in amphibolites of the ca. 3.45 Ga Dwalile Greenstone Remnant, revealing μ142Nd values ranging from - 7.9 ± 4.4 to - 6.1 ± 4.3 ppm. The μ142Nd deficits do not correlate with age, lithological unit, or sample locality. Instead, our results reveal that two distinct mantle domains were involved in the formation of the AGC crust. The two reservoirs can be distinguished by their μ142Nd signatures. Mantle-derived rocks tapped the enriched reservoir with negative μ142Nd at least until 3.46 Ga, whereas the granitoids preserved a negative μ142Nd signature that formed by incorporation of older AGC crust at least until 3.22 Ga. The oldest gneisses with no μ142Nd anomaly are up to 3.64 Ga in age, indicating that a modern terrestrial 142Nd reservoir was already present by early Archean times.

  9. Re-appraisal of the Santa Rita Greenstone Belt stratigraphy, central Brazil, based on new U-Pb SHRIMP age and Sm-Nd data of felsic metavolcanic rocks

    International Nuclear Information System (INIS)

    Pimentel, Marcio Martins; Jost, Hardy; Fuck, Reinhardt Adolfo; Junges, Sergio Luiz; Armstrong, Richard; Resende, Marcelo Goncalves

    2000-01-01

    The Santa Rita greenstone belt represents one of the supracrustal belts of the Archaen terranes of Goias, central Brazil. The stratigraphic sequence of this greenstone belt comprises a lower of komatities and basalts and an upper metasedimentary unit made of carbonaceous schits, chert, iron formation and marble, unconformably overlain by clastic metasedimentary rocks. Felsic metavolcanics occur at the interface between the metabasalts and the upper metasedimentary pile. U-Pb SHRIMP age for zircons from the felsic metavolcanics reveal that it is not part of the Archaean sequence, but represents the product of mesoproterozoic (1580 ± 12 Ma) magmatic event. Sm-Nd isotopic data (initial e CHUR values between -10.5 and -14.9) and T DM values of 3.0 and 3.2 Ga, within the range of the surrounding TTG terranes, indicate that the original felsic magmas were produced by re-melting of Archaen crust. The data demonstrate that the Goias greenstone belt contains infolded and imbricated proterozoic rocks, as previously suggested by Sm-Nd isotopic analyses of some of the upper detrital metasedimentary rocks. (author)

  10. Re-appraisal of the Santa Rita Greenstone Belt stratigraphy, central Brazil, based on new U-Pb SHRIMP age and Sm-Nd data of felsic metavolcanic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Pimentel, Marcio Martins; Jost, Hardy; Fuck, Reinhardt Adolfo; Junges, Sergio Luiz [Brasilia Univ., DF (Brazil). Inst. de Geociencias]. E-mail: marcio@unb.br; Armstrong, Richard [Australian National Univ., Canberra, ACT (Australia). Research School of Earth Sciences; Resende, Marcelo Goncalves [Universidade Catolica de Brasilia, DF (Brazil). Curso de Graduacao em Engenharia Ambiental

    2000-03-01

    The Santa Rita greenstone belt represents one of the supracrustal belts of the Archaen terranes of Goias, central Brazil. The stratigraphic sequence of this greenstone belt comprises a lower of komatities and basalts and an upper metasedimentary unit made of carbonaceous schits, chert, iron formation and marble, unconformably overlain by clastic metasedimentary rocks. Felsic metavolcanics occur at the interface between the metabasalts and the upper metasedimentary pile. U-Pb SHRIMP age for zircons from the felsic metavolcanics reveal that it is not part of the Archaean sequence, but represents the product of mesoproterozoic (1580 {+-} 12 Ma) magmatic event. Sm-Nd isotopic data (initial e{sub CHUR} values between -10.5 and -14.9) and T{sub DM} values of 3.0 and 3.2 Ga, within the range of the surrounding TTG terranes, indicate that the original felsic magmas were produced by re-melting of Archaen crust. The data demonstrate that the Goias greenstone belt contains infolded and imbricated proterozoic rocks, as previously suggested by Sm-Nd isotopic analyses of some of the upper detrital metasedimentary rocks. (author)

  11. Chemical and isotopic studies of granitic Archean rocks, Owl Creek Mountains, Wyoming: Geochronology of an Archean granite, Owl Creek Mountains, Wyoming

    International Nuclear Information System (INIS)

    Hedge, C.E.; Simmons, K.R.; Stuckless, J.S.

    1986-01-01

    Rubidium-strontium analyses of whole-rock samples of an Archean granite from the Owl Creek Mountains, Wyo., indicate an intrusive age of 2640 ± 125 Ma. Muscovite-bearing samples give results suggesting that these samples were altered about 2300 Ma. This event may have caused extensive strontium loss from the rocks as potassium feldspar was altered to muscovite. Alteration was highly localized in nature as evidence by unaffected rubidium-strontium mineral ages in the Owl Creek Mountains area. Furthermore, the event probably involved a small volume of fluid relative to the volume of rock because whole-rock δ 18 O values of altered rocks are not distinct from those of unaltered rocks. In contrast to the rubidium-strontium whole-rock system, zircons from the granite have been so severely affected by the alteration event, and possibly by a late-Precambrian uplift event, that the zircon system yields little usable age information. The average initial 87 Sr/ 86 Sr (0.7033 ± 0.0042) calculated from the isochron intercept varies significantly. Calculated initial 87 Sr/ 86 Sr ratios for nine apparently unaltered samples yield a range of 0.7025 to 0.7047. These calculated initial ratios correlate positively with whole-rock δ 18 O values; and, therefore, the granite was probably derived from an isotopically heterogeneous source. The highest initial 87 Sr/ 86 Sr ratio is lower than the lowest reported for the metamorphic rocks intruded by the granite as it would have existed at 2640 Ma. Thus, the metamorphic sequence, at its current level of exposure, can represent no more than a part of the protolith for the granite

  12. Boninitic metavolcanic rocks and island arc tholeiites from the Older Metamorphic Group (OMG) of Singhbhum Craton, eastern India: Geochemical evidence for Archean subduction processes

    Digital Repository Service at National Institute of Oceanography (India)

    Manikyamba, C.; Ray, J.; Ganguly, S.; Singh, M.R.; Santosh, M.; Saha, A.; Satyanarayanan, M.

    a dent that th for high deg stability fie mantle plu or komatiit tial melting to explain 1999). It ha ally hot man magma tha eration of regime corr tions canno In the mod drating oce cases, subd wedge to g at depths ∼ boninites re Therefore...

  13. Generation of TTG rocks in the Archean: insight from numerical simulations

    Science.gov (United States)

    Rozel, Antoine; Golabek, Gregor; Gerya, Taras; Jain, Charitra; Tackley, Paul

    2017-04-01

    We study the creation of primordial continental crust (TTG rocks) for the first time employing fully self-consistent numerical models of thermochemical convection on a global scale. Starting from a pyrolytic bulk composition and an initially hot core, we first generate oceanic crust and depleted mantle. In our model, the basaltic material is both erupted at the surface and intruded at the base of the crust following a predefined partitioning. Second, we track the pressure-temperature conditions of the newly formed hydrated basalt and check if it matches the conditions necessary for the formation of primordial continental crust. We show that the "heat-pipe" model (assuming 100% eruption and no intrusion) proposed to be the main heat loss mechanism during the Archean epoch (Moore & Webb 2013) is not able to produce continental crust since it forms a cold and thick lithosphere. We systematically test various mechanical properties of the brittle domain (friction coefficients). Using our parameter study, we are also able to show that an intrusion fraction close to 70% (in agreement with [Crisp 1984]) combined with a friction coefficient of 0.2 products the expected amount of the three main petrological TTG compositions previously reported (Moyen 2011). This study represents a major step towards the production of self-consistent convection models able to generate the continental crust of the Earth. REFERENCES Crisp, J. A. (1984), Rates of magma emplacement and volcanic output. Journal of Volcanology and Geothermal Research, 20(3-4), 177-211. Moore, W., and A. Webb (2013), Heat-pipe earth. Nature, 501, 501-505, doi:10.1038/nature12473. Moyen, J. (2011), The composite archaean grey gneisses: Petrological significance, and evidence for a non-unique tectonic setting for archaean crustal growth. Lithos, 123, 21-36, doi: 10.1016/j.lithos.2010.09.015.

  14. Pb, Sr, and Nd isotopic compositions of a suite of Large Archean, igneous rocks, eastern Beartooth Mountains - Implications for crust-mantle evolution

    Science.gov (United States)

    Wooden, J. L.; Mueller, P. A.

    1988-01-01

    Compositionally diverse Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains (Montana and Wyoming) were studied and shown to have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial values lower than predicted for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. A model involving subduction of continental detritus and contamination of the overlying mantle is suggested.

  15. Early mantle dynamics inferred from 142Nd variations in Archean rocks from southwest Greenland

    DEFF Research Database (Denmark)

    Rizo, Hanika; Boyet, Maud; Blichert-Toft, Janne

    2013-01-01

    of the Greenland samples from a source formed in the Hadean. This mantle source is the oldest yet identified on Earth and therefore provides key information about the nature and evolution of early-differentiated reservoirs. In contrast, modern mantle-derived rocks from around the world do not have Nd-142 anomalies......The composition and evolution of the silicate Earth during Hadean/Eoarchean times are widely debated and largely unknown due to the sparse geological record preserved from Earth's infancy. The short-lived Sm-146-Nd-142 chronometer applied to 3.8-3.7 Ga old mantle-derived amphibolites from the Isua...... Supracrustal Belt (ISB) in southwest Greenland has revealed ubiquitous Nd-142 excesses in these rocks compared to modern samples and terrestrial Nd standards. Because the parent isotope, Sm-146, was extant only during the first few hundred million years of Solar System history, this implies derivation...

  16. High Ni in Archean tholeiites

    Science.gov (United States)

    Arndt, Nicholas T.

    1991-03-01

    Archean tholeiites generally have higher Ni, Co. Cr and Fe than most younger tholeiites with similar MgO contents. These characteristics cannot be attributed to high T or P batch melting in the Archean mantle, because, although such melts are enriched in siderophile elements, they have higher MgO than normal tholeiites. As primary melts fractionate to lower MgO, they lose Ni, Co and Cr. Nor can the differences between Archean and younger tholeiites be attributed to secular variation in mantle compositions because Archean komatiites have Ni, Co, Cr contents similar to modern (Gorgona) komatiites. It is suggested that the high siderophile element content of Archean tholeiites results from mixing of either komatiitic with basaltic magmas, as might occur in an ascending, melting mantle plume or column, or of komatiite and more evolved rocks, as may take place when komatiite encounters and assimilates crustal rocks.

  17. Variability in Rock Thermal Properties in the Late Archean Crust of the Kapuskasing Structural Zone and Implications for its Thermal Structure and Metamorphic History.

    Science.gov (United States)

    Merriman, J. D.; Whittington, A. G.; Hofmeister, A. M.

    2017-12-01

    The thermal properties of rocks such as internal heat production and thermal diffusivity (α) play a key role in determining the thermal structure of the lithosphere, and consequently, the rates and styles of metamorphism within the crust. Over the last decade, measurements of α using the method laser flash analysis have shown the ability of a rock to conduct heat can vary by as much as a factor of 5 between common rock types, and decrease by up to a factor of 10 for the same rock between 25-1000°C. Here we present a preliminary model for the variability in rock throughout the crust based on measurements of the α of a suite of 100 samples from late Archean crust exposed in and around the Kapuskasing Structural Zone in Ontario, Canada. Preliminary results suggest that α is controlled primarily by mineralogy, and can vary not only between different rock types as described above, but also within the same rock by a factor of 1.5 (or more). Thermal diffusivity results were combined with heat producing element concentrations measured with ICP-MS to create a thermal model of the Kapuskasing Structural Zone prior its uplift and exposure. To provide additional constraints for P-T conditions within the pre-uplift KSZ crust, a combination of trace-element and pseudosection thermobarometry was used to estimate metamorphic temperatures during an extended period of crustal stability at the end of the Archean. Preliminary results were compared to finite-difference numerical models of the steady-state geothermal gradient using heat production back-calculated to 2.6 Ga. Results suggest a minimum thickness of the continental lithosphere during the late Archean of at least 150 km. To test the response of the crust to the effects of large thermal events such as pluton emplacement, we also performed time-dependent models of the thermal structure of the pre-uplift KSZ crust. These models suggest that heat from thermal events in the upper and middle crust result in a more insulating

  18. Evidence for ancient atmospheric xenon in Archean rocks and implications for the early evolution of the atmosphere

    Science.gov (United States)

    Pujol, M.; Marty, B.; Burnard, P.; Hofmann, A.

    2012-12-01

    The initial atmospheric xenon isotopic composition has been much debated over the last 4 decades. A Non radiogenic Earth Atmospheric xenon (NEA-Xe) composition has been proposed to be the best estimate of the initial signature ([1]). NEA-Xe consists of modern atmospheric Xe without fission (131-136Xe) or radioactive decay (129Xe) products. However, the isotope composition of such non-radiogenic xenon is very different to that of potential cosmochemical precursors such as solar or meteoritic Xe, as it is mass-fractionated by up to 3-4 % per amu relative to the potential precursors, and it is also elementally depleted relative to other noble gases. Because the Xe isotopic composition of the Archean appears to be intermediate between that of these cosmochemical end-members and that of the modern atmosphere, we argued that isotopic fractionation of atmospheric xenon did not occur early in Earth's history by hydrodynamic escape, as postulated by all other models ([1], [2], [3]), but instead was a continuous, long term process that lasted during at least the Hadean and Archean eons. Taken at face value, the decrease of the Xe isotopic fractionation from 1.6-2.1 % amu-1 3.5 Ga ago ([4]) to 1 % amu-1 3.0 Ga ago (Ar-Ar age in fluid inclusions trapped in quartz from the same Dresser Formation, [5]) could reflect a secular variation of the atmospheric Xe signature. Nevertheless, up until now, all data showing an isotopic mass fractionation have been measured in rocks and fluids from the same formation (Dresser Formation, Western Australia, aged 3.5 Ga), and have yet to be confirmed in rocks from different locations. In order to better constrain xenon isotopic fractionation of the atmosphere through time, we decided to analyze barites from different ages, geological environments and metamorphism grade. We started this study with barite from the Fig Tree Formation (South Africa, aged 3.26 Ga). This barite was sampled in old mines so have negligible modern exposure time. It is

  19. Major, trace and platinum group element (PGE) geochemistry of Archean Iron Ore Group and Proterozoic Malangtoli metavolcanic rocks of Singhbhum Craton, Eastern India: Inferences on mantle melting and sulphur saturation history

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, M.R.; Manikyamba, C.; Ray, J.; Ganguly, S.; Santosh, M.; Saha, A.; Rambabu, S.; Sawant, S.S.

    .86 0.90 0.84 3.93 0.87 0.86 0.86 0.85 0.91 Y 26.1 26.4 29.7 25.8 26.8 26.6 26.3 29.0 26.2 29.3 La 20.17 20.32 21.84 19.45 20.18 20.06 20.17 20.93 20.10 21.38 Ce 42.56 43.25 45.28 41.55 43.10 42.44 42.95 42.48 42.59 44.13 Pr 3.79 3.88 4.24 3.78 3.86 3....82 3.86 4.05 3.84 4.11 Nd 19.56 19.92 21.82 19.38 20.18 19.88 19.84 21.25 19.82 21.16 Sm 4.23 4.39 4.76 4.27 4.44 4.41 4.42 4.66 4.34 4.57 Eu 1.43 1.17 1.25 1.08 1.27 1.21 1.17 1.30 1.23 1.21 Gd 5.47 5.66 6.02 5.34 5.56 5.46 5.47 5.82 5.59 5.85 Tb 0...

  20. Development of a mixed seawater-hydrothermal fluid geochemical signature during alteration of volcanic rocks in the Archean (∼2.7 Ga) Abitibi Greenstone Belt, Canada

    Science.gov (United States)

    Brengman, Latisha A.; Fedo, Christopher M.

    2018-04-01

    conclude that seafloor silicification in hydrothermal depositional settings is capable of producing rocks that resemble marine chemical precipitates such as banded iron formation, and could be a process that is widespread in the Archean. Consequently, because silicified volcanic rocks from the HMG possess mixed seawater and hydrothermal rare-earth element characteristics similar to Archean iron formations and cherts, we suggest caution must be exercised when interpreting the geochemical information preserved in metamorphosed rocks where original genesis is unknown.

  1. The chemical conditions of the late Archean Hamersley basin inferred from whole rock and pyrite geochemistry with Δ33S and δ34S isotope analyses

    Science.gov (United States)

    Gregory, Daniel D.; Large, Ross R.; Halpin, Jacqueline A.; Steadman, Jeffery A.; Hickman, Arthur H.; Ireland, Trevor R.; Holden, Peter

    2015-01-01

    The well-preserved late Archean sedimentary rocks of the Fortescue and Hamersley Basins in Western Australia offer fascinating insights into early earth ocean chemistry prior to the Great Oxidation Event (GOE). In this study, we use a combination of whole rock geochemistry, LA-ICPMS trace element analysis of sedimentary pyrite and pyrrhotite and SHRIMP-SI sulfur isotope analyses to elucidate the chemical changes in these sedimentary rocks. These proxies are used to examine chemical conditions of the ocean during the late Archean. Two to three periods of oxygen enrichment prior to the deposition of banded iron formations (BIF) can be identified. One minor stage of general increase in whole rock enrichment factors and trace element content of pyrite is observed up stratigraphy in the Jeerinah Formation, Fortescue Basin and a more substantial stage is present in the Paraburdoo and Bee Gorge Members of the Wittenoom Formation, Hamersley Basin. Some of the trace element enrichments indicate organic matter burial flux (Ni, Cr, Zn, Co and Cu) which suggests an increase in biological productivity. If the increased biological activity reflects an increase in cyanobacteria activity then an associated increase in oxygen is likely to have occurred during the deposition of the Bee Gorge Member. An increase in atmospheric oxygen would result in continental weathering of sulfide and other minerals, increasing the trace element content of the water column via erosion and avoiding excessive depletion of trace elements due to drawdown in seawater. Since some of these trace elements may also be limiting nutrients (such as Mo and Se) for the cyanobacteria, the degree of biological productivity may have further increased due to the increasing amount of trace elements introduced by oxygenation in a positive feedback loop. These periods of increased productivity and oxygen rise stopped prior to the onset of BIF deposition in the Hamersley Basin. This may be due to the ocean reaching an

  2. Petrochronology in constraining early Archean Earth processes and environments: Barberton greenstone belt, South Africa

    Science.gov (United States)

    Grosch, Eugene

    2017-04-01

    Analytical and petrological software developments over the past decade have seen rapid innovation in high-spatial resolution petrological techniques, for example, laser-ablation ICP-MS, secondary ion microprobe (SIMS, nano-SIMS), thermodynamic modelling and electron microprobe microscale mapping techniques (e.g. XMapTools). This presentation will focus on the application of petrochronology to ca. 3.55 to 3.33 billion-year-old metavolcanic and sedimentary rocks of the Onverwacht Group, shedding light on the earliest geologic evolution of the Paleoarchean Barberton greenstone belt (BGB) of South Africa. The field, scientific drilling and petrological research conducted over the past 8 years, aims to illustrate how: (a) LA-ICP-MS and SIMS U-Pb detrital zircon geochronology has helped identify the earliest tectono-sedimentary basin and sediment sources in the BGB, as well as reconstructing geodynamic processes as early as ca. 3.432 billion-years ago; (b) in-situ SIMS multiple sulphur isotope analysis of sulphides across various early Archean rock units help to reconstruct atmospheric, surface and subsurface environments on early Archean Earth and (c) the earliest candidate textural traces for subsurface microbial life can be investigated by in-situ LA-ICP-MS U-Pb dating of titanite, micro-XANES Fe-speciation analysis and metamorphic microscale mapping. Collectively, petrochronology combined with high-resolution field mapping studies, is a powerful multi-disciplinary approach towards deciphering petrogenetic and geodynamic processes preserved in the Paleoarchean Barberton greenstone belt of South Africa, with implications for early Archean Earth evolution.

  3. Evaluating the earliest traces of Archean sub-seafloor life by NanoSIMS

    Science.gov (United States)

    Mcloughlin, N.; Grosch, E. G.; Kilburn, M.; Wacey, D.

    2012-12-01

    The Paleoarchean sub-seafloor has been proposed as an environment for the emergence of life with titanite microtextures in pillow lavas argued to be the earliest traces of microbial micro-tunneling (Furnes et al. 2004). Here we use a nano-scale ion microprobe (NanoSIMS) to evaluate possible geochemical traces of life in 3.45 Ga pillow lavas of the Barberton Greenstone Belt, South Africa. We investigated both surface and drill core samples from the original "Biomarker" outcrop in the Hooggenoeg Fm. Pillow lava metavolcanic glass contain clusters of segmented microcrystalline titanite filaments, ~4μm across and sedimentary sulfides (δ34S = +8 to -23‰). We propose that the Hooggenoeg sulfides probably formed during early fluid-rock-microbe interaction involving sulfate-reducing microbes (c.f. Rouxel et al. 2008). The pillow lavas were then metamorphosed, the glass transformed to a greenschist facies assemblage and titanite growth encapsulated the microbial sulfides. In summary, the extreme sulfur isotope fractionations reported here independently point towards the potential involvement of microbes in the alteration of Archean volcanic glass. In situ sulfur isotope analysis of basalt-hosted sulfides may provide an alternative approach to investigating the existence of an Archean sub-seafloor biosphere that does not require the mineralization of early microbial microborings with organic linings.

  4. Oxidative release of chromium from Archean ultramafic rocks, its transport and environmental impact – A Cr isotope perspective on the Sukinda valley ore district (Orissa, India)

    International Nuclear Information System (INIS)

    Paulukat, Cora; Døssing, Lasse N.; Mondal, Sisir K.; Voegelin, Andrea R.; Frei, Robert

    2015-01-01

    Highlights: • Cr in lateritic soil profiles in Sukinda valley are partly highly negatively fractionated. • Oxidative weathering and mining operations affect the Cr isotope composition of the local surface water. • Isotopically heavy Cr from land is probably preserved during its transport to the sea. • The environmental impact of toxic Cr(VI) can potentially be diminished by microbial mats. - Abstract: This study investigates Cr isotope fractionation during soil formation from Archean (3.1–3.3 Ga) ultramafic rocks in a chromite mining area in the southern Singhbhum Craton (Orissa, India). The Cr-isotope signatures of two studied weathering profiles, range from non-fractionated mantle values to negatively fractionated values as low as δ 53 Cr = −1.29 ± 0.04‰. Local surface waters are isotopically heavy relative to the soils. This supports the hypothesis that during oxidative weathering isotopically heavy Cr(VI) is leached from the soils to runoff. The impact of mining pollution is observed downstream from the mine where surface water Cr concentrations are significantly increased, accompanied by a shift to less positive δ 53 Cr values relative to upstream unpolluted surface water. A microbial mat sample indicates that microbes have the potential to reduce and immobilize Cr(VI), which could be a factor in controlling the hazardous impact of Cr(VI) on health and environment. The positive Cr isotope signatures of the Brahmani estuary and coastal seawater collected from the Bay of Bengal further indicate that the positively fractionated Cr isotope signal from the catchment area is preserved during its transport to the sea. Isotopically lighter Cr(VI) downstream from the mine is probably back-reduced to Cr(III) during riverine transport leading to similar Cr-isotope values in the estuary as observed upstream from the mine

  5. Basic rocks in Finland

    International Nuclear Information System (INIS)

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

    1992-10-01

    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

  6. Cyclic formation and stabilization of Archean lithosphere by accretionary orogenesis: Constraints from TTG and potassic granitoids, North China Craton

    Science.gov (United States)

    Wang, Wei; Cawood, Peter A.; Liu, Shuwen; Guo, Rongrong; Bai, Xiang; Wang, Kang

    2017-09-01

    Accretionary orogens are major sites of modern continental growth, yet their role in the development of Archean continental crust remains enigmatic. Diverse granitoid suites from tonalite-trondhjemite-granodiorite (TTG) to potassic granitoids appeared during late Archean, representing a period of major continental formation and stabilization. In this study, whole-rock geochemical and zircon U-Pb and Lu-Hf isotopic data are reported for Neoarchean granitoid gneisses from the Northern Liaoning Terrane, northeastern North China Craton (NCC). Older granitoid gneisses ( 2592-2537 Ma) define three magmatic zones migrating from southeast to northwest, each showing a common magmatic evolution from high-pressure TTGs to medium-/low-pressure TTGs and potassic granitoids. They have depleted zircon ƐHf(t) of +0.5 to +8.7. Younger 2529-2503 Ma potassic granitoids and TTGs occur throughout the terrane, which are marked by variable zircon ƐHf(t) of -4.7 to +8.1, and are coeval with regional high-grade metamorphism. Petrogenetic modeling and changing Sr/Y and (La/Yb)N of the granitoids suggest that the crust experienced episodic thickening and thinning and became progressively evolved through development of potassic granitoids and sedimentary successions. The metavolcanic basement to the granitoids display tholeiitic to calc-alkaline affinities, together with the top-to-the-northwest thrusting and associated volcanogenic massive sulfide-type Cu-Zn deposits, suggesting cyclic crustal formation of Northern Liaoning within an accretionary orogen with a SE-dipping subduction polarity. Cyclic crustal thickening and thinning is related to tectonic switching from advancing to retreating relations between the downgoing and overriding plate. After 2530 Ma, this accretionary system accreted to the ancient continental nucleus of NCC (Anshan-Benxi Terrane), signifying final lithosphere stabilization.

  7. Evidence of early Archean crust in northwest Gondwana, from U-Pb and Hf isotope analysis of detrital zircon, in Ediacaran surpacrustal rocks of northern Spain

    Science.gov (United States)

    Naidoo, Thanusha; Zimmermann, Udo; Vervoort, Jeff; Tait, Jenny

    2018-03-01

    The Mora Formation (Narcea Group) is one of the oldest Precambrian supracrustal successions in northern Spain. Here, we use U-Pb and in situ Hf isotope analysis on detrital zircon to determine its age and provenance. The youngest U-Pb dates constrain the maximum depositional age of the Mora Formation at 565 ± 11 Ma. Results indicate: (1) a dominant Ediacaran zircon population (33%; 565-633 Ma, Cadomian) within a spectrum of Neoproterozoic ages (40%; 636-996 Ma); and (2) smaller Mesoproterozoic (5%; 1004-1240 Ma), Palaeoproterozoic (11%; 1890-2476 Ma) and Archean (11%; 2519-3550 Ma) populations. Results here do not point to one specific cratonic source area; instead, detritus may have been derived from the West African craton and Amazonia, or even the concealed Iberian basement. The lack of 1.3-1.8 Ga grains suggests exclusion of the Sahara Craton as a major source, but this is not certain. This mixed composition favours a complex source history with reworking of detritus across terrane/craton boundaries. Hafnium isotope compositions indicate a range of crustal and juvenile sources, with initial ɛHf values between -15.8 and 11.1, and Hf model ages from 0.8 to 3.7 Ga. For Neoproterozoic zircons (80%), juvenile components (ɛHf(i) +10) may be related to Rodinia fragmentation and the onset of an active margin setting leading to the Cadomian orogeny. Palaeoproterozoic to Paleoarchean grains (20%) all have negative ɛHf values and Meso- to Eoarchean Hf model ages. This indicates an early (Archean) sialic crustal component for northwestern Gondwana.

  8. Lavalleja group (Uruguay), a neoproterozoic metavolcanic-metasedimentary sequence:geochemistry and geochronological features

    International Nuclear Information System (INIS)

    Preciozzi, F.; Sanchez Bettucci, L.; Basei, M.

    2003-01-01

    The Lavalleja Group is located in the southern portion of the Dom Feliciano Belt, being correlated with the Porongos and Brusque Groups in Brazil. This Group has a granitic-gneissic basement probably associated to the Valentines Block and Pavas Terrane, with ages ranging from 1.75 to 2.1 Ga (U-Pb determination). An older basement probably occurs. This Group is characterized by narrow bands of metasedimentary and metavolcanic rocks and is subdivided into three formations (Sánchez-Bettucci, 1998). The first one includes lithologies with a very low to anquimetamorphism degree; the second one is formed by rocks with low metamorphism degree (lower greenschist facies) and the last one presents an upper greenschist facies in transition to upper and lower amphibolite facies. They correspond respectively to the Minas, Fuente del Puma and Zanja del Tigre Formations. The Minas Formation includes only metasedimentary rocks: limestones, dolomites, metapelites, quartzites and arkoses. The Fuente del Puma Formation is formed by three units (Sanchez-Bettucci, 1998): the sedimentary, volcanic and hornblenditic gabbros units. The Zanja del Tigre Formation shows lithologies of medium metamorphism degree, developed to the east of the two other Formations. Syn-collisional to postectonic granitic bodies are associated to the Lavalleja Group. These granitic bodies correspond to the Carapé Complex. The paleoproterozoic basement of Lavalleja Group and Carapé Complex is named Campanero Unit

  9. Reconciling atmospheric temperatures in the early Archean

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Bird, Dennis K.; Rosing, Minik Thorleif

    rock record. The goal of this study is to compile and reconcile Archean geologic and geochemical features that are in some way controlled by surface temperature and/or atmospheric composition, so that at the very least paleoclimate models can be checked by physical limits. Data used to this end include...... weathering on climate). Selective alteration of δD in Isua rocks to values of -130 to -100‰ post-dates ca. 3.55Ga Ameralik dikes, but may be associated with a poorly defined 2.6-2.8Ga metamorphic event that is coincident with the amalgamation of the “Kenorland supercontinent.”...

  10. Finite strain analysis of metavolcanics and metapyroclastics in gold-bearing shear zone of the Dungash area, Central Eastern Desert, Egypt

    Science.gov (United States)

    Kassem, Osama M. K.; Abd El Rahim, Said H.

    2014-11-01

    The Dungash gold mine area is situated in an EW-trending quartz vein along a shear zone in metavolcanic and metasedimentary host rocks in the Eastern Desert of Egypt. These rocks are associated with the major geologic structures, which are attributed to various deformational stages of the Neoproterozoic basement rocks. Field geology, finite strain and microstructural analyses were carried out and the relation-ships between the lithological contacts and major/minor structures have been studied. The R f/ϕ and Fry methods were applied on the metavolcano-sedimentary and metapyroclastic samples from 5 quartz veins samples, 7 metavolcanics samples, 3 metasedimentary samples and 4 metapyroclastic samples in Dungash area. Finite-strain data show that a low to moderate range of deformation of the metavolcano-sedimentary samples and axial ratios in the XZ section range from 1.70 to 4.80 for the R f/ϕ method and from 1.65 to 4.50 for the Fry method. We conclude that finite strain in the deformed rocks is of the same order of magnitude for all units of metavolcano-sedimentary rocks. Furthermore, the contact between principal rock units is sheared in the Dungash area under brittle to semi-ductile deformation conditions. In this case, the accumulated finite strain is associated with the deformation during thrusting to assemble nappe structure. It indicates that the sheared contacts have been formed during the accumulation of finite strain.

  11. Where are uranium and thorium stored in the Archean basement

    Energy Technology Data Exchange (ETDEWEB)

    Schwinner, R

    1949-01-01

    The author advances a theory which makes it possible to predict where prospecting for new deposits of uranium and thorium should prove successful. According to this theory, such deposits occur chiefly where the equatorial and the meridional branches of the oldest primitive rock systems cross one another. An outline of the earth's Archean basement is included.

  12. An Archean Biosphere Initiative

    Science.gov (United States)

    Anbar, A. D.; Boyd, E. S.; Buick, R.; Claire, M.; DesMarais, D.; Domagal-Goldman, D.; Eigenbrode, J.; Erwin, D.; Freeman, K.; Hazen, R.; hide

    2011-01-01

    The search for life on extrasolar planets will necessarily focus on the imprints of biolgy on the composition of planetary atmospheres. The most notable biological imprint on the modern terrestrial atmosphere is the presence of 21 % O2, However, during most of the past 4 billion years, life and the surface environments on Earth were profoundly different than they are today. It is therefore a major goal of the astrobiology community to ascertain how the O2 content of the atmosphere has varied with time. and to understand the causes of these variations. The NAI and NASA Exobiology program have played critical roles in developing our current understanding of the ancient Earth's atmosphere, supporting diverse observational, analytical, and computational research in geoscience, life science, and related fields. In the present incarnation of the NAI, ongoing work is investigating (i) variations in atmospheric O2 in the Archean to the Cambrian, (ii) characterization of the redox state of the oceans shortly before, during and after the Great Oxidation Event (GOE), and (iii) unraveling the complex connections between environmental oxygenation, global climate, and the evolution of life.

  13. Pb-Pb geochronology in zircon of the basement rocks of the southern portion of the Araguaia Belt - Paraiso do Tocantins region, Brazil

    International Nuclear Information System (INIS)

    Arcanjo, Silvia Helena de Souza; Moura, Candido Augusto Veloso

    2000-01-01

    Recent geochronological studies of the basement orthogneisses of the northern region of the Araguaia belt showed the occurrence of both Archean (2.85 Ga) and Early Proterozoic (1.85 Ga) rocks. The oldest gneisses were grouped in the Colmeia Complex, the younger were named the Cantao Gneiss. In the southern portion of the Araguaia belt, the basement sequences include metavolcanic-sedimentary rocks, tonalitic, calc-silicate, and alkaline gneisses, and granitic rocks. All of these sequences have been considered as Archean in age, although no geochronological data are available to test this hypothesis. The metavolcanic-sedimentary rocks are included in the Rio do Coco Group, while the granitic rocks are represented by the Serrote and Matanca granites. The tonalitic and calc-silicate gneisses were grouped with Colmeia and Rio do Mangues Complexes, and the alkaline gneisses in the Monte Santo Suite. These gneisses were investigated geochronologically by single zircon Pb-evaporation methods in order to define their stratigraphic interrelationships, and to contribute to a greater understanding of the geological evolution of this crustal segment. The single zircon ages of the tonalitic and calc-silicate gneisses range between 1.8 and 2.1 Ga. An age of about 1.0 Ga, was obtained for the alkaline gneisses of Serra da Estrela (Monte Santo Suite). These data along with the single zircon age of 1.85 Ga. published for the Serrote Granite, indicate the widespread occurrence of Proterozoic rocks in the basement of the southern part of Araguaia belt. However, the existence of Arquean sequences in this region can not be discarded since the volcanic-sedimentary rocks of the Rio do Coco Group have not as yet been dated. The correlation of tonalitic and calc-silicate gneisses with the Colmeia Complex was not confirmed, so these gneisses have been grouped with the Early proterozoic Rio dos Mangues Complex. Thus, it is suggested that a significant part of the basement of the southern

  14. Drilling for the Archean Roots of Life and Tectonic Earth in the Barberton Mountains

    Directory of Open Access Journals (Sweden)

    Nicola McLoughlin

    2009-09-01

    Full Text Available In the Barberton Scientific Drilling Program (BSDP we successfully completed three drill holes in 2008 across strategically selected rock formations in the early Archean Barberton Greenstone Belt, South Africa. This collaborative project’s goal is to advance understanding of geodynamic and biogeochemical processes of the young Earth. The program aims to better define and characterize Earth’s earliest preserved ocean crust shear zones and microbial borings in Archean basaltic glass, and to identify biogeochemical fingerprints of ancient ecological niches recorded in rocks. The state-of-the-art analytical and imaging work will address the question of earliest plate tectonics in the Archean, the δ18O composition, the redox state and temperature of Archean seawater, and the origin of life question.

  15. Structural analysis for metavolcanics and their metapyroclastics at gold deposit of the Mahd Ad Dahab area, Arabian Shield, Saudi Arabia

    Science.gov (United States)

    Kassem, Osama M. K.; Al Bassam, Abdel Aziz M.; Zaidi, Faisal K.

    2013-11-01

    The present study focuses on the gold mining in Mahd Ad Dahab region of Saudi Arabia. The study aims to assess the spatial relationship between tectonic contacts in Mahd Ad Dahab area and to provide a meaningful hypothesis relating gold metallogeny to the evolution of the Arabian Shield. Distribution and localization of gold occurrences in the study area was envisaged based on the different styles of microstructures and the major deformation phases affecting the area. The detailed petrographical and mineralogical investigations indicate that the metavolcanic rocks at the Mahd Ad Dahab gold mine area can be classified into metabasalt, metaandesite, and the felsic varieties (metadacite, metarhyodacite and metarhyolite) associating their metapyroclastics (conglomerate and tuffs). Furthermore, quartz forms allotriomorphic crystals which exhibit wavy extinction, deformational lamina and foliation due to subsequent deformations. Furthermore, we conclude that finite strain in the deformed rocks is of the same order of magnitude for all units of metavolcano-sedimentary rocks. Furthermore, contacts formed during intrusion of plutons with some faults in the Mahd Ad Dahab area under brittle to semi-ductile deformation conditions. In this case, finite strain accumulated during superimposed deformation on the already assembled nappe structure. It indicates that the contacts formed during the accumulation of finite strain.

  16. NanoSIMS analysis of Archean fossils and biomarkers

    International Nuclear Information System (INIS)

    Kilburn, M.R.; Wacey, D.

    2008-01-01

    The study of fossils and biomarkers from Archean rocks is of vital importance to reveal how life arose on Earth and what we might expect to find on other planets such as Mars. The Cameca NanoSIMS 50 has the unique ability to measure stable isotopes and map biologically relevant elements at the micron-scale, in situ. This makes it the perfect tool for testing the biogenicity of a range of putative biomarkers from early Archean rocks (∼3.50 billion-year-old). NanoSIMS has been used to investigate ambient inclusion trails (AITs) in a 3.43 Ga beach sand deposit from the Pilbara craton, Western Australia. Chemical maps of the light elements necessary for life (C, N and O) and several transition metals commonly associated with biological processing (Ni, Zn and Fe), coupled with 13 C/ 12 C isotope ratios from carbonaceous linings, strongly suggest a biological component in the formation of AITs

  17. Geochemistry of Metavolcanics and Granitic Intrusive from Western ...

    African Journals Online (AJOL)

    User

    the Afar Depression. The Arabian-Nubian Shield covers vast terrain to the north and northwest of the Afar Depression and in eastern Eritrea (Beyene and Abdelsalam, 2005 and references therein). ... great interest because it may represent the complete sequence of rocks spanning from the Late. Proterozoic to the present ...

  18. Two distinct origins for Archean greenstone belts

    Science.gov (United States)

    Smithies, R. Hugh; Ivanic, Tim J.; Lowrey, Jack R.; Morris, Paul A.; Barnes, Stephen J.; Wyche, Stephen; Lu, Yong-Jun

    2018-04-01

    rare, and were probably only preserved when fortuitously stabilised by granitic magmatism related to the evolution of later variable-Th/Nb greenstones. The rarity of constant-Th/Nb trends suggests that either processes forming them never dominated Archean greenstone evolution, or that such greenstones simply were rarely preserved. Metamorphic mobility of Th renders the Th/Yb-Nb/Yb plot inappropriate for interpreting Eoarchean greenstone units worldwide. Nevertheless, such sequences appear dominated by volcanic rocks that, in modern settings, reflect only the embryonic or initiation stages of subduction. They probably record subduction failure rather than anything resembling modern-style subduction.

  19. Archean inheritance in zircon from late Paleozoic granites from the Avalon zone of southeastern New England: an African connection

    Science.gov (United States)

    Zartman, R.E.; Don, Hermes O.

    1987-01-01

    In southeastern New England the Narragansett Pier Granite locally intrudes Carboniferous metasedimentary rocks of the Narragansett basin, and yields a monazite UPb Permian emplacement age of 273 ?? 2 Ma. Zircon from the Narragansett Pier Granite contains a minor but detectable amount of an older, inherited component, and shows modern loss of lead. Zircon from the late-stage, aplitic Westerly Granite exhibits a more pronounced lead inheritance -permitting the inherited component to be identified as Late Archean. Such old relict zircon has not been previously recognized in Proterozoic to Paleozoic igneous rocks in New England, and may be restricted to late Paleozoic rocks of the Avalon zone. We suggest that the Archean crustal component reflects an African connection, in which old Archean crust was underplated to the Avalon zone microplate in the late Paleozoic during collision of Gondwanaland with Avalonia. ?? 1987.

  20. Zircon's Archean of the Ural

    International Nuclear Information System (INIS)

    Krasnobaev, A.A.; Cherednichenko, N.V.

    2005-01-01

    The age of zircons from metamorphic rocks of the Taratashsky complex located on the Western slope of the South Urals was determined by the methods of U-Pb isotope dating. The age values obtained suggest a two-stage model of the complex evolution at early stages of its existence. The age of 2913±133 mln. years identifies the age of granulite metamorphism, while the age 2127±65 mln. years indicates the period of the most intensive transformations of the rocks within the complex, which were accompanied by occurrence of high-temperature diaphthorites [ru

  1. Archean Age Fossils from Northwestern Australia (Approximately 3.3 to 3.5 GA, Warrawoona Group, Towers Formation)

    Science.gov (United States)

    Smith, Penny A. Morris

    1999-01-01

    Archean aged rocks from the Pilbara Block area of western Australia (Warrawoona Group, Towers Formation, -3.3-3.5 Ga) contain microfossils that are composed of various sizes of spheres and filaments. The first descriptions of these microfossils were published in the late 1970's (Dunlop, 1978; Dunlop, et. al., 1978). The authenticity of the microfossils is well established. The small size of the microfossils prevents isotope dating, at least with the present technology. Microbiologists, however, have established guidelines to determine the authenticity of the Archean aged organic remains (Schopf, Walter, 1992).

  2. Granite-hosted molybdenite mineralization from Archean ...

    Indian Academy of Sciences (India)

    2013). The Bundelk- hand Tectonic Zone has now been established as an Archean ... The molybdenite is only encountered in geochemical analysis. (f) Mo vein is ...... Collins W J, Beams S D, White A J R and Chappell B W. 1982 Nature and ...

  3. Venus and the Archean Earth: Thermal considerations

    International Nuclear Information System (INIS)

    Sleep, N.H.

    1989-01-01

    The Archean Era of the Earth is not a direct analog of the present tectonics of Venus. In this regard, it is useful to review the state of the Archean Earth. Most significantly, the temperature of the adiabatic interior of the Earth was 200 to 300 C hotter than the current temperature. Preservation biases limit what can be learned from the Archean record. Archean oceanic crust, most of the planetary surface at any one time, has been nearly all subducted. More speculatively, the core of the Earth has probably cooled more slowly than the mantle. Thus the temperature contrast above the core-mantle boundary and the vigor of mantle plumes has increased with time on the Earth. The most obvious difference between Venus and the present Earth is the high surface temperature and hence a low effective viscosity of the lithosphere. In addition, the temperature contrast between the adiabatic interior and the surface, which drives convection, is less on Venus than on the Earth. It appears that the hot lithosphere enhanced tectonics on the early Venus significantly enough that its interior cooled faster than the Earth's. The best evidence for a cool interior of Venus comes from long wavelength gravity anomalies. The low interior temperatures retard seafloor spreading on Venus. The high surface temperatures on Venus enhance crustal deformation. That is, the lower crust may become ductile enough to permit significant flow between the upper crust and the mantle. There is thus some analogy to modern and ancient areas of high heat flow on the Earth. Archean crustal blocks typically remained stable for long intervals and thus overall are not good analogies to the deformation style on Venus

  4. A summary of Rb-Sr isotope studies in the Archean Hopedale Block and the adjacent proterozoic Makkovik subprovince, Labrador

    International Nuclear Information System (INIS)

    Grant, N.K.; Hickman, M.H.; Marzano, M.S.; Ermanovics, I.F.

    1983-01-01

    Rb-Sr isotope study of thirteen whole-rock suites of Archean and Proterozoic rocks from Hopedale block and Makkovik Subprovince shows that the crustal history began about 3115 Ma ago. We tentatively recognize younger crustal segments that formed 2920 Ma ago, from which Kanairktok intrusives were derived at 2832 +- 178 Ma. In Makkovik Subprovince the Island Harbour granites range in age from 1843 +- 90 to 1794 +- 71 Ma. These ages overlap with the 1847 +-87 Ma age for Kanairktok shear zone mylonites. The Island Harbour granodiorites from inland localities to the southwest are contaminated with Archean rocks in Makkovik Subprovince and their initial 87 Sr/ 86 ratios imply a crustal contribution to their source. In contrast, the Island Harbour granites of Striped Island were derived from a mantle source. The sills of Striped Island are 1635 +- 47 Ma old. An undeformed northeast trending Kikkertavak dolerite dyke from Hopedale block is 1206 +- 120 Ma

  5. 2.9-1.9 Ga paleoalterations of Archean granitic basement of the Franceville basin (Gabon)

    Science.gov (United States)

    Mouélé, Idalina Moubiya; Dudoignon, Patrick; El Albani, Abderrazak; Meunier, Alain; Boulvais, Philippe; Gauthier-Lafaye, François; Paquette, Jean-Louis; Martin, Hervé; Cuney, Michel

    2014-09-01

    The Archean granitoids in the Kiéné area, Gabon, are overlained by the Paleoproterozoic sediments of the Franceville basin (2.1 Ga). The basin is known for its high-grade uranium deposits among which some have been forming natural nuclear fission reactors. Most of the studies were dedicated to the FA-FB Paleoproterozoic sediments hosting these uranium deposits. Little is known on the Archean basement itself and specifically on the hydrous alteration events it experienced before and after the sediment deposition. The present work is focused on their petrographical, mineralogical and geochemical characterization. Dating the successive alteration events has been attempted on altered monazite crystals. Rocks in different alteration states have been sampled from eight drill cores crosscutting the Archean - Paleoproterozoic unconformity. The Archean granitoids observed in the deepest levels exhibit typical petrographical features of a propylitic alteration while they are intensely illitized up to the unconformity. The propylitic alteration is mainly pervasive but the original texture of the granitoïds is conserved in spite of the formation of new minerals: Mg-chlorite, allanite and epidote forming a typical paragenesis. The illitic alteration is much more invasive near the unconformity. The illitization process leads to the replacement of feldspars and the corrosion of quartz crysals by an illitic matrix while the ferromagnesian minerals are pseudomorphosed by a Fe-chlorite + phengite + hematite assemblage. The final fluid-rock interaction step is marked by fissural deposits of calcite and anhydrite. The δ13C isotopic data show that the fissural carbonates precipitated from diagenetic fluids enriched carbon products deriving from the maturation of organic matter. The U-Pb isotopic analyzes performed on monazite crystals have dated three distinct events: 3.0-2.9 Ga (magmatic), 2.6 Ga (propylitic alteration) and 1.9 Ga (diagenetic illitization). The calculation of

  6. Late Archean Surface Ocean Oxygenation (Invited)

    Science.gov (United States)

    Kendall, B.; Reinhard, C.; Lyons, T. W.; Kaufman, A. J.; Anbar, A. D.

    2009-12-01

    Oxygenic photosynthesis must have evolved by 2.45-2.32 Ga, when atmospheric oxygen abundances first rose above 0.001% present atmospheric level (Great Oxidation Event; GOE). Biomarker evidence for a time lag between the evolution of cyanobacterial oxygenic photosynthesis and the GOE continues to be debated. Geochemical signatures from sedimentary rocks (redox-sensitive trace metal abundances, sedimentary Fe geochemistry, and S isotopes) represent an alternative tool for tracing the history of Earth surface oxygenation. Integrated high-resolution chemostratigraphic profiles through the 2.5 Ga Mt. McRae Shale (Pilbara Craton, Western Australia) suggest a ‘whiff’ of oxygen in the surface environment at least 50 M.y. prior to the GOE. However, the geochemical data from the Mt. McRae Shale does not uniquely constrain the presence or extent of Late Archean ocean oxygenation. Here, we present high-resolution chemostratigraphic profiles from 2.6-2.5 Ga black shales (upper Campbellrand Subgroup, Kaapvaal Craton, South Africa) that provide the earliest direct evidence for an oxygenated ocean water column. On the slope beneath the Campbellrand - Malmani carbonate platform (Nauga Formation), a mildly oxygenated water column (highly reactive iron to total iron ratios [FeHR/FeT] ≤ 0.4) was underlain by oxidizing sediments (low Re and Mo abundances) or mildly reducing sediments (high Re but low Mo abundances). After drowning of the carbonate platform (Klein Naute Formation), the local bottom waters became anoxic (FeHR/FeT > 0.4) and intermittently sulphidic (pyrite iron to highly reactive iron ratios [FePY/FeHR] > 0.8), conducive to enrichment of both Re and Mo in sediments, followed by anoxic and Fe2+-rich (ferruginous) conditions (high FeT, FePY/FeHR near 0). Widespread surface ocean oxygenation is suggested by Re enrichment in the broadly correlative Klein Naute Formation and Mt. McRae Shale, deposited ~1000 km apart in the Griqualand West and Hamersley basins

  7. Petrogenetic significance of rare earth element patterns of selected samples of Ingaldhal metavolcanics, Karnatak State, India : Consortium studies no. 1

    Energy Technology Data Exchange (ETDEWEB)

    Murali, A V; Pawaskar, P B; Reddy, G R; Sankar Das, M [Bhabha Atomic Research Centre, Bombay (India). Analytical Chemistry Div.; Subbarao, K V [Indian Inst. of Tech., Bombay, Geology Dept.; Vasudev, V N [Chitradurga Copper Co., Bangalore (India)

    1979-07-01

    Rare earth element contents of metavolcanics of the Ingaldhal area of Chitradurga schist belt in India have been analysed by instrument neutron activation analysis on the coarse fraction (approximately 30 mesh) and radiochemical neutron activation analysis on the fine fraction (-200 mesh). The coarse and fine fractions of the samples were irradiated separately in the CIRUS reactor at a flux of 10/sup 13/n cm/sup -2/ sec/sup -1/ for 24 hours. The counting assembly consisted of a Ge(Li) detector (45 cc; coupled to 1024 channel analyser) and the system resolution was FWHM 2.3 keV at 1332 keV. Results are presented.

  8. Sulfate was a trace constituent of Archean seawater

    DEFF Research Database (Denmark)

    Crowe, Sean Andrew; Paris, Guillaume; Katsev, Sergei

    2014-01-01

    In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water column...

  9. Evolution of the Archean Mohorovičić discontinuity from a synaccretionary 4.5 Ga protocrust

    Science.gov (United States)

    Hamilton, Warren B.

    2013-12-01

    This review evaluates and rejects the currently dominant dogmas of geodynamics and geochemistry, which are based on 1950s-1970s assumptions of a slowly differentiating Earth. Evidence is presented for evolution of mantle, crust, and early Moho that began with fractionation of most crustal components, synchronously with planetary accretion, into mafic protocrust by ~ 4.5 Ga. We know little about Hadean crustal geology (> 3.9 Ga) except that felsic rocks were then forming, but analogy with Venus, and dating from the Moon, indicate great shallow disruption by large and small impact structures, including huge fractionated impact-melt constructs, throughout that era. The mantle sample and Archean (preserved Archean crust to its base, and of the thick mafic volcanic rocks erupted on that crust. Lower TTG crust, kept mobile by its high radioactivity and by insulating upper crust, rose diapirically into the upper crust as dense volcanic rocks sagged synformally. The mobile lower crust simultaneously flowed laterally to maintain subhorizontal base and surface, and dragged overlying brittler granite-and-greenstone upper crust. Petrologically required garnet-rich residual protocrust incrementally delaminated, sank through low-density high-mantle magnesian dunite, and progressively re-enriched upper mantle, mostly metasomatically. Archean and earliest Proterozoic craton stabilization and development of final Mohos followed regionally complete early delamination of residual protocrust, variously between ~ 2.9 and 2.2 Ga. Where some protocrust remained, Proterozoic basins, filled thickly by sedimentary and volcanic rocks, developed on Archean crust, beneath which delamination of later residual protocrust continued top-down enrichment of upper mantle. That reenrichment enabled modern-style plate tectonics after ~ 600 Ma, with a transition regime beginning ~ 850 Ma.

  10. Geostable molecules and the Late Archean 'Whiff of Oxygen'

    Science.gov (United States)

    Summons, R. E.; Illing, C. J.; Oduro, H. D.; French, K. L.; Ono, S.; Hallmann, C.; Strauss, H.

    2012-12-01

    Geoscientists continue to debate the course of oxygenation of Earth's surface environment. The prevailing scenarios include the one articulated by Cloud, Holland and Walker which proposes an initially anoxic or very low O2 atmosphere but one where oxygen-releasing Photosystem II appeared early. A strong imbalance between sources & sinks kept the atmospheric pO2 low until the 'Great Oxidation Event' or GOE at c. 2.45 Ga. An alternative scenario is that the GOE marks the first appearance of oxygen-releasing photosynthesis (Kopp et al., 2005). However, there is a wealth of geochemical and paleontological data that is consistent with the presence of both cyanobacteria (e.g. Bosak et al., 2009) and traces of environmental oxygen (e.g. Anbar et al., 2007) several hundred million years prior to the GOE. Here we report new studies of 2.7-2.5 Ga sedimentary rocks from the Transvaal Supergroup of the Kaapvaal Craton and from the Mt. Bruce Supergroup of the Pilbara Craton. We used improved analytical techniques which identified and excluded minor sources of contaminating hydrocarbons. We also focused on mineral-occluded hydrocarbons that show distribution patterns that co-vary with lithology and replicated earlier identifications of molecular fossils that require oxygen for their biosynthesis (Waldbauer et al., 2008, 2011). Some sediment horizons in the studied sections contain diagenetic products of pigments characteristic of phototrophic green sulfur bacteria and their co-variance with inorganic proxies, each leading to similar paleoenvironmental reconstructions and confirming the authenticity of this signal. The carotenoid-derived biomarkers, although diagnostic for anoxygenic phototrophs, indicate that the seas of the Hamersley and Transvaal Basins provided an intermittent supply of hydrogen sulfide to the photic zone. Indirectly, this suggests replenishment of the marine sulfate pool from the oxidative weathering of metal sulfides. Organic sulfur in these same sediments

  11. Early Archean serpentine mud volcanoes at Isua, Greenland, as a niche for early life.

    Science.gov (United States)

    Pons, Marie-Laure; Quitté, Ghylaine; Fujii, Toshiyuki; Rosing, Minik T; Reynard, Bruno; Moynier, Frederic; Douchet, Chantal; Albarède, Francis

    2011-10-25

    The Isua Supracrustal Belt, Greenland, of Early Archean age (3.81-3.70 Ga) represents the oldest crustal segment on Earth. Its complex lithology comprises an ophiolite-like unit and volcanic rocks reminiscent of boninites, which tie Isua supracrustals to an island arc environment. We here present zinc (Zn) isotope compositions measured on serpentinites and other rocks from the Isua supracrustal sequence and on serpentinites from modern ophiolites, midocean ridges, and the Mariana forearc. In stark contrast to modern midocean ridge and ophiolite serpentinites, Zn in Isua and Mariana serpentinites is markedly depleted in heavy isotopes with respect to the igneous average. Based on recent results of Zn isotope fractionation between coexisting species in solution, the Isua serpentinites were permeated by carbonate-rich, high-pH hydrothermal solutions at medium temperature (100-300 °C). Zinc isotopes therefore stand out as a pH meter for fossil hydrothermal solutions. The geochemical features of the Isua fluids resemble the interstitial fluids sampled in the mud volcano serpentinites of the Mariana forearc. The reduced character and the high pH inferred for these fluids make Archean serpentine mud volcanoes a particularly favorable setting for the early stabilization of amino acids.

  12. River Valley pluton, Ontario - A late-Archean/early-Proterozoic anorthositic intrusion in the Grenville Province

    Science.gov (United States)

    Ashwal, Lewis D.; Wooden, Joseph L.

    1989-01-01

    This paper presents Nd, Sr, and Pb isotopic data indicating a late-Archean/early-Proterozoic age for the River Valley anorthositic pluton of the southwestern Grenville Province of Sudbury, Ontario. Pb-Pb isotopic data on 10 whole-rock samples ranging in composition from anorthosite to gabbro yield an age of 2560 + or - 155 Ma. The River Valley pluton is thus the oldest anorthositic intrusive yet recognized within the Grenville Province. The Sm-Nd isotopic system records an age of 2377 + or - 68 Ma. High Pb-208/Pb-204 of deformed samples relative to igneous-textured rocks implies Th introduction and/or U loss during metamorphism in the River Valley area. Rb-Sr data from igneous-textured and deformed samples and from mineral separates give an age of 2185 + or - 105 Ma, indicating substantial disturbance of the Rb-Sr isotopic system.

  13. On the photosynthetic potential in the very Early Archean oceans.

    Science.gov (United States)

    Avila, Daile; Cardenas, Rolando; Martin, Osmel

    2013-02-01

    In this work we apply a mathematical model of photosynthesis to quantify the potential for photosynthetic life in the very Early Archean oceans. We assume the presence of oceanic blockers of ultraviolet radiation, specifically ferrous ions. For this scenario, our results suggest a potential for photosynthetic life greater than or similar to that in later eras/eons, such as the Late Archean and the current Phanerozoic eon.

  14. Awareness for natural radiation potential zones in Archean Terrain of Chhattisgarh State

    International Nuclear Information System (INIS)

    Diwan, H.D.; Pande, S.K.

    2015-01-01

    In the environment, the natural radiations emitted by rocks and soils containing radioactive minerals, largely affected the human being in various aspects. The Chhattisgarh region characterized by the mineral of natural radiations with their relative distribution found in Granitic rocks of Archean age. Adjacent to Cratonic margins, exposures of outer fringes became suitable sites for radiation spread. It constituting towards the emission of radiation by the intrinsic content of minerals present in the host rock i.e. the terrestrial sources of radiation. The Archean terrain covers the surrounding areas of oval cup shaped sedimentary basin and it lies in the S.O.I. toposheet no. 64 G. H.I.K.L. To locate the marked potential zone for natural radiation, the investigation nearby aquatic component of main river and tributaries of Mahanadi river system is important. The presence of Granitic/ Pegmatite rocks at the boundaries of shield areas became promising areas for radiation generating mineral components. Occurrence in the potential zones expressed as lense shaped deposits or strips in dimension of IX1/2 with few hundred long belt. Presence of weathering of Uraninite minerals content remain yellow orange coloured impressions on the surface. In urban areas the background radiation in form of ionic radiation by the residential dwelling units accredates radiations. It needs awareness for Natural Radiation of under zones (NRPZ) in the region. To ensure the effective awareness programme, the area under consideration of natural radiation should take care of socially sustainable activities and spatio-temporal spread to motivate and implement various safety provisions. The model experiments can be sued from R and D point of view, also to alert the people to provide 'Safety, health and welfare of society'. (author)

  15. Lavalleja group (Uruguay) a neoproterozoic metavolcanic-sedimentary sequence: ore deposits

    International Nuclear Information System (INIS)

    Sanchez Bettucci, L.; Preciozzi, F.; Ramos, V.

    2003-01-01

    The Lavalleja meta volcano-sedimentary Group, exposed along the Dom Feliciano Belt, is located in the southeast of Uruguay and formed by meta gabbros, basic and acid meta volcanic rocks. It was developed during late Proterozoic-Early Paleozoic Brasiliano orogeny. Based on the geochemical signature, Sánchez-Bettucci et al. (2001) suggested a back-arc basin tectonic setting. The metamorphic grade increases to the southeast, ranging from very low grade to lower green schist facies in the Minas formation, to lower amphibolite facies in the Fuente del Puma and Zanja del Tigre Formations (Sánchez-Bettucci et al., 2001). The metamorphic mineral assemblages correspond to a low-pressure regional metamorphism associated with a high thermal gradient (Sánchez-Bettucci et al., 2001).A compressive deformational event, that probably corresponds to the basin closure of the Lavalleja Group during a continental collision was recognized. The petrology, geochemistry, metamorphism grade, and tectonic setting are consistent with a back-arc basin as suggested by Sánchez-Bettucci et al. (2001)

  16. Iron isotopes in ancient and modern komatiites: Evidence in support of an oxidised mantle from Archean to present

    Science.gov (United States)

    Hibbert, K. E. J.; Williams, H. M.; Kerr, A. C.; Puchtel, I. S.

    2012-03-01

    The mantle of the modern Earth is relatively oxidised compared to the initially reducing conditions inferred for core formation. The timing of the oxidation of the mantle is not conclusively resolved but has important implications for the timing of the development of the hydrosphere and atmosphere. In order to examine the timing of this oxidation event, we present iron isotope data from three exceptionally well preserved komatiite localities, Belingwe (2.7 Ga), Vetreny (2.4 Ga) and Gorgona (0.089 Ga). Measurements of Fe isotope compositions of whole-rock samples are complemented by the analysis of olivine, spinel and pyroxene separates. Bulk-rock and olivine Fe isotope compositions (δ57Fe) define clear linear correlations with indicators of magmatic differentiation (Mg#, Cr#). The mean Fe isotope compositions of the 2.7-2.4 Ga and 0.089 Ga samples are statistically distinct and this difference can be explained by greater extent of partial melting represented by the older samples and higher mantle ambient temperatures in the Archean and early Proterozoic relative to the present day. Significantly, samples of all ages define continuous positive linear correlations between bulk rock δ57Fe and V/Sc and δ57Fe and V, and between V/Sc and V with TiO2, providing evidence for the incompatible behaviour of V (relative to Sc) and of isotopically heavy Fe. Partial melting models calculated using partition coefficients for V at oxygen fugacities (fO2s) of 0 and + 1 relative to the fayalite-magnetite-quartz buffer (FMQ) best match the data arrays, which are defined by all samples, from late Archean to Tertiary. These data, therefore, provide evidence for komatiite generation under moderately oxidising conditions since the late Archean, and argue against a change in mantle fO2 concomitant with atmospheric oxygenation at ~ 2.4 Ga.

  17. An investigation of the Archean climate using the NCAR CCm

    International Nuclear Information System (INIS)

    Jenkins, G.S.

    1991-01-01

    The Archean (2.5 to 3.8 billion years ago) is of interest climatically, because of the 'Faint-Young Sun Paradox', which can be characterized by the Sun's reduced energy output. This lower energy output leads to a frozen planet if the climate existed as it does today. But, the geologic record shows that water was flowing at the earth's surface 3.8 billion years ago. Energy Balance Models (EBMs) and one-dimensional radiative-convective (1DRC) models predict a frozen planet for this time period, unless large carbon dioxide (CO2) concentrations exist in the Archean atmosphere. The goal is to explore the Archean climate with the National Center for Atmospheric Research (NCAR), Community Climate Model (CCM). The search for negative feedbacks to explain the 'Faint-Young Sun Paradox' is the thrust of this study. This study undertakes a series of sensitivity simulations which first explores individual factors that may be important for the Archean. They include rotation rate, lower solar luminosity, and land fraction. Then, these climatic factors along with higher CO2 concentrations are combined into a set of experiments. A faster rotation rate may have existed in the Archean. The faster rotation rate simulations show warmer globally averaged surface temperatures that are caused by a 20 percent decrease in the total cloud fraction. The smaller cloud fraction is brought about by dynamical changes. A global ocean is a possibility for the Archean. A global ocean simulation predicts 4 K increase in global mean surface temperatures compared to the present-day climate control

  18. Sulfur MIF, Organic Haze, and the Gaia Hypothesis in the Archean

    Science.gov (United States)

    Domagal-Goldman, S.; James, K. F.

    2006-05-01

    The presence of mass-independent fractionation (MIF) of sulfur isotopes in Archean sedimentary rocks provides evidence for a low-O2 atmosphere prior to 2.4 Ga. Recent data suggest that S-MIF vanished transiently between ~3.2 Ga and 2.8 Ga. The absence of S-MIF after 2.4 Ga is commonly attributed to the rise of O2 in the atmosphere, as the presence of free O2 would have oxidized all sulfur species, thereby erasing any MIF created by atmospheric photochemistry. However, if free O2 did not appear in the atmosphere until 2.4 Ga, then why did S-MIF disappear transiently much earlier? Could S-MIF have been eliminated from the rock record without the presence of free atmospheric O2? We used a 1-dimensional photochemical model to demonstrate how this might have happened. Increasing the CH4/CO2 ratio in the model atmosphere results in the formation of organic haze. If the haze was sufficiently thick, it would have blocked out much of the solar UV radiation shortward of 220 nm that dissociates SO2 and SO, and thereby causes MIF. The haze should also have caused anti-greenhouse cooling and may have triggered the (putative) 2.8-Ga glaciations. Speculatively, an increase in CH4 at 3.0 Ga could have been caused by the evolution of methanogens, while a CH4 decrease at 2.7 Ga could correspond to the evolution of cyanobacteria. The presence of an optically thin organic haze between 2.4 and 2.7 Ga may explain the larger S-MIF values seen at this time, as compared to the early Archean. If such an organic haze existed, it could have resulted in a biologically-mediated negative feedback loop that stabilized the Archean climate. This feedback loop would have operated as follows: an increase in the biological CH4 flux would have led to an increase in haze thickness and a stronger anti-greenhouse effect, cooling the surface. The surface cooling would have caused a reduction of methanogen productivity, thus offsetting the original increase in the CH4 flux. Such stabilizing feedbacks

  19. Archean komatiite volcanism controlled by the evolution of early continents.

    Science.gov (United States)

    Mole, David R; Fiorentini, Marco L; Thebaud, Nicolas; Cassidy, Kevin F; McCuaig, T Campbell; Kirkland, Christopher L; Romano, Sandra S; Doublier, Michael P; Belousova, Elena A; Barnes, Stephen J; Miller, John

    2014-07-15

    The generation and evolution of Earth's continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50-30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean-Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits.

  20. Hydrothermal Processes in the Archean - New Insights from Imaging Spectroscopy

    NARCIS (Netherlands)

    Ruitenbeek, F.J.A. van

    2007-01-01

    The aim of this research was to gain new insights in fossil hydrothermal systems using airborne imaging spectroscopy. Fossil submarine hydrothermal systems in Archean greenstone belts and other geologic terranes are important because of their relationship with volcanic massive sulfide (VMS) mineral

  1. PALEOARCHEAN MAFIC ROCKS OF THE SOUTHWESTERN SIBERIAN CRATON: PRELIMINARY GEOCHRONOLOGY AND GEOCHEMICAL CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    A. V. Ivanov

    2017-01-01

    Full Text Available The Siberian craton consists of Archean blocks, which were welded up into the same large unit by ca 1.9 Ga [Gladkochub et al., 2006; Rojas-Agramonte et al., 2011]. The history of the constituent Archean blocks is mosaic because of limited number of outcrops, insufficient sampling coverage because of their location in remote regions and deep forest and difficulties with analytical studies of ancient rocks, which commonly underwent metamorphic modifications and secondary alterations. In this short note, we report data on discovery of unusual for Archean mafic rocks of ultimate fresh appearance. These rocks were discovered within southwestern Siberian craton in a region near a boundary between Kitoy granulites of the Sharyzhalgai highgrade metamorphic complex and Onot green-schist belt (Fig. 1. Here we present preliminary data on geochronology of these rocks and provide their geochemical characterization.

  2. Deep-Time drilling in the Australian Archean: the Agouron Institute geobiological drilling project. (Invited)

    Science.gov (United States)

    Buick, R.

    2010-12-01

    The Agouron Institute has sponsored deep-time drilling across the South African Archean-Proterozoic boundary, investigating the rise of oxygen over an onshore-offshore environmental transect. It is now supporting a drilling program in the Australian Archean of the Pilbara Craton, addressing a similar theme but with the added goal of resolving controversy over the age and origin of hydrocarbon biomarker molecules in ancient kerogenous shales. As these have been claimed to provide evidence for the evolution of oxygenic photosynthesis long before the rise of atmospheric oxygen to persistently high levels during the ~2.3 Ga “Great Oxidation Event”, their syngenesis with their host shales is thus of critical importance for the interpretation of Earth’s early oxygenation history. During the first drilling season, 3 holes were drilled using techniques and equipment to minimize organic geochemical contamination (new drill-string components cleaned before drilling potentially biomarker-bearing rocks, pre-contamination of drilling fluid with a synthetic organic compound of similar geochemical characteristics to biomarkers, sterile cutting and storage of samples immediately upon retrieval from the core-barrel). The initial hole was a blank control for organic geochemistry, drilled into rocks too metamorphosed to retain biomarker molecules. These rocks, cherts, carbonates and pelites of the 3.52 Ga Coucal Formation, Coonterunah Group, have been metamorphosed to upper greenschist facies at temperatures near 500°C and so should have had any ancient soluble hydrocarbons destroyed. However, because they contain both carbonate and organic carbon, these rocks can instead provide isotopic information about the earliest evolution of biological metabolism as they possess residues of both the reactant and product sides of the carbon-fixation reaction. The second hole sampled an on-shore section of carbonates and kerogenous shales in the ~2.65 Ga Carawine Dolomite and Lewin Shale

  3. The Behaviour of Chromium Isotopes during the Oxidative Weathering of Ultramafic Rocks

    DEFF Research Database (Denmark)

    Paulukat, Cora Stefanie; Døssing, Lasse Nørbye; Mondal, Sisir K.

    The chromium isotope system has been proven to be a redox-sensitve proxy in ancient and modern environmental studies (e.g. [1], [2]). In this study we investigated Cr isotope fractionation during soil formation from Archean (3.1-3.3 Ga) ultramafic rocks, intruded into metamorphic rocks of the Iron...

  4. Molybdenum isotopes in modern marine hydrothermal Fe/Mn deposits: Implications for Archean and Paleoproterozoic Mo cycles

    Science.gov (United States)

    Goto, K. T.; Hein, J. R.; Shimoda, G.; Aoki, S.; Ishikawa, A.; Suzuki, K.; Gordon, G. W.; Anbar, A. D.

    2016-12-01

    Molybdenum isotope (δ98/95Mo) variations recorded in Archean and Paleoproterozoic Fe/Mn-rich sediments have been used to constrain ocean redox conditions at the time of deposition (Canfield et al., 2013 PNAS; Planavsky et al., 2014 Nat. Geo.; Kurzweil et al., 2015 GCA). However, except for hydrogenous Fe-Mn crusts (Siebert et al., 2003), δ98/95Mo variation of modern Fe and Mn oxide deposits has been poorly investigated. Marine hydrothermal systems are thought to be the major source of Fe and Mn in Archean and Paleoproterozoic Fe- and Mn-rich sediments. Hence, to accurately interpret Mo isotope data of those ancient sedimentary rocks, it is important to evaluate the possible influence of hydrothermally derived Mo on δ98/95Mo of modern Fe- and Mn-rich sediments. In this study, we analyzed Mo isotopic compositions of one hydrothermal Fe oxide and 15 Mn oxides from five different hydrothermal systems in the modern ocean. The Fe oxide is composed mainly of goethite, and has a δ98/95Mo of 0.7‰, which is 1.4‰ lighter than that of present-day seawater. The observed offset is similar to isotope fractionation observed during adsorption experiments of Mo on goethite (Δ98/95Mogoethite-solution = -1.4 ± 0.5%; Goldberg et al., 2009 GCA). The 15 hydrothermal Mn oxides show large variations in δ98/95Mo ranging from -1.7 to 0.5‰. However, most of the values are similar to those of modern hydrogenous Fe-Mn crusts (Siebert et al., 2003 EPSL), and fall within the range of estimated δ98/95Mo of Mn oxides precipitated from present-day seawater using the isotope offset reported from adsorption experiments (Δ98/95Mo = -2.7 ± 0.3‰; Wasylenki et al., 2008 GCA). These findings indicate that seawater is the dominant source of Mo for modern hydrothermal Fe and Mn deposits. However, the observed large variation indicates that the contribution Mo from local hydrothermal systems is not negligible. The oceanic Mo inventory during the Archean and Paleoproterozoic is thought to be

  5. Decreasing µ142Nd Variation in the Archean Convecting Mantle from 4.0 to 2.5 Ga: Heterogeneous Domain Mixing or Crustal Recycling?

    Science.gov (United States)

    Brandon, A. D.; Debaille, V.

    2014-12-01

    The 146Sm-142Nd (t1/2=68 Ma) chronometer can be used to examine silicate differentiation in the first 400 Ma of Earth history. Early fractionation between Sm and Nd is recorded in cratonic Archean rocks in their 142Nd/144Nd ratios that that deviate up to ±20 ppm, or μ142Nd - ppm deviation relative to the present-day convecting mantle at 0. These values likely record early extraction of incompatible trace element (ITE) enriched material with -μ142Nd, either as crust or late stage residual melt from a magma ocean, and resulting in a complimentary ITE depleted residual mantle with +μ142Nd. If this early-formed ITE-enriched material was re-incorporated rapidly back into the convecting mantle, both ITE-enriched and ITE-depleted mantle domains would have been established in the Hadean. Alternatively, if it was early-formed crust that remained stable it could have slowly eroded and progressively remixed into the convecting mantle as subducted sediment during the Archean. Each of these scenarios could potentially explain the decrease in the maximum variation in µ142Nd from ±20 at 4.0 Ga to 0 at 2.5 Ga [1,2,3]. In the scenario where these variations reflect mixing of mantle domains, this implies long mantle mixing times of greater than 1 Ga in the Archean in order to preserve the early-formed heterogeneities. This can be achieved in a stagnant lid tectonic regime in the Archean with sporadic and short subduction cycles [2]. This scenario would also indicate that mixing times in the convecting mantle were much slower than the previously proposed 100 Ma in the Hadean and Archean. In the alternative scenario, sediment with -µ142Nd was progressively mixed into the mantle via subduction in the Archean [3]. This scenario doesn't require slow mantle mixing times or a stagnant-lid regime. It requires crustal resident times of up to 750 Ma to maintain a steady supply of ancient sediment recycling over the Archean. Each of these scenarios evoke very contrasting conditions for

  6. Triassic rejuvenation of unexposed Archean-Paleoproterozoic deep crust beneath the western Cathaysia block, South China

    Science.gov (United States)

    Li, Xi-Yao; Zheng, Jian-Ping; Xiong, Qing; Zhou, Xiang; Xiang, Lu

    2018-01-01

    Jurassic (ca. 150 Ma) Daoxian basalts from the western Cathaysia block (South China) entrained a suite of deep-seated crustal xenoliths, including felsic schist, gneiss and granulite, and mafic two-pyroxene granulite and metagabbro. Zircon U-Pb-Hf isotopic, whole-rock elemental and Sr-Nd-Pb isotopic compositions have been determined for these valuable xenoliths to reveal the poorly-known, unexposed deep crust beneath South China. Detrital zircons from the garnet-biotite schists show several populations of ages at 0.65-0.5 Ga, 1.1-0.75 Ga, 1.6-1.4 Ga, 1.8-1.7 Ga, 2.5-2.4 Ga, 2.8 Ga, and 3.5 Ga, representing a multi-sourced, meta-sedimentary origin with deposition time at the early Cambrian. One mafic granulite contains zircons with concordant U-Pb ages of Neoarchean ( 2520 Ma), as well as Hf model ages of 2.8-2.6 Ga and positive εHf(t) values (up to 6.3), suggesting an accretion of juvenile crust in Neoarchean, probably as the main framework of the lower crust. Geochemical and geochronological evidence shows the mafic granulite and metagabbro were produced by underplating of magmas derived from the depleted asthenosphere and mixed with EM2-type materials during the Late Triassic (205-196 Ma). This magmatic underplating also resulted in the widespread metamorphism of the mafic lower crust and felsic middle crust (e.g., the felsic granulite and gneiss) at 202-201 Ma. We suggest the existence of a highly evolved Archean-Paleoproterozoic basement beneath the western Cathaysia block, which experienced episodic accretion and reworking and the strong rejuvenation during the Triassic. A three-layered structure of the lower crust could exist beneath the Daoxian area during the Jurassic time: its upper layer is an evolved Archean-Paleoproterozoic basement; the middle hybrid layer represents a mixture of Archean-Paleoproterozoic basement with newly accreted/reworked Proterozoic to Phanerozoic materials; and the deeper layer consists of mafic granulites derived from the

  7. Oxidative Weathering of Archean Sulfides: Implications for the Great Oxidation Event

    Science.gov (United States)

    Johnson, A.; Romaniello, S. J.; Reinhard, C.; Garcia-Robledo, E.; Revsbech, N. P.; Canfield, D. E.; Lyons, T. W.; Anbar, A. D.

    2015-12-01

    The first widely accepted evidence for oxidation of Earth's atmosphere and oceans occurs ~2.45 Ga immediately prior to the Great Oxidation Event (GOE). A major line of evidence for this transition includes the abundances and isotopic variations of redox-sensitive transition metals in marine sediments (e.g., Fe, Mo, Re, Cr, and U). It is often assumed that oxidative weathering is required to liberate these redox-sensitive elements from sulfide minerals in the crust, and hence that their presence in early Archean marine sediments signifies that oxidative weathering was stimulated by small and/or transient "whiffs" of O2 in the environment.1 However, studies of crustal sulfide reactivity have not been conducted at O2 concentrations as low as those that would have prevailed when O2 began its rise during the late Archean (estimated at molybdenite oxidation kinetics at the nanomolar O2 concentrations that are relevant to late Archean environments. These measurements were made using recently developed, highly sensitive optical O2 sensors to monitor the rates at which the powdered minerals consumed dissolved O2 in a range of pH-buffered solutions.3Our data extend the range of experimental pyrite oxidation rates in the literature by three orders of magnitude from ~10-3 present atmospheric O2 to ~10-6. We find that molybdenite and pyrite oxidation continues to <1 nM O2 (4 x 10-6 present atmospheric O2). This implies that oxidative weathering of sulfides could occur under conditions which preserve MIF S fractionation. Furthermore, our results indicate that the rate law and reaction order of pyrite oxidation kinetics change significantly at nanomolar concentrations of O2 when compared to previous compilations.2 Our results provide new empirical data that should allow for more precise quantitative constraints on atmospheric pO2 based on the sedimentary rock record. 1Anbar, A.D. et al., 2007. Science, 317, i. 5846: 1903-1906. 2Williamson & Rimstidt, 1994. Geochim. et Cosmochim

  8. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: is this really Archean crust? REPLY

    Science.gov (United States)

    Premo, Wayne R.

    2010-01-01

    The comments from McGrew and Snoke are well received and their concerns for the interpretations in our paper (Premo et al., 2008), which questions the original contention that the Angel Lake orthogneiss is an Archean rock, are many and varied—all of which we will attempt to address. As they point out, this issue is an important one as this particular crustal exposure may delimit the southwestern extent of the Archean Wyoming province (Foster et al., 2006; Mueller and Frost, 2006), which has implications for the true crustal evolution of this region of the Great Basin and perhaps more importantly its relationship (if any) to the location of the world-class gold deposits of north-central Nevada (e.g., Howard, 2003).

  9. Hazy Archean Earth as an Analog for Hazy Earthlike Exoplanets

    Science.gov (United States)

    Arney, Giada; Meadows, Victoria; Domagal-Goldman, Shawn; Claire, Mark; Schwieterman, Edward

    2015-01-01

    Hazy exoplanets may be common (Bean et al. 2010, Sing et al. 2011, Kreidberg et al 2014), and in our solar system, Venus and Titan have photochemically-produced hazes. There is evidence that Earth itself had a hydrocarbon haze in the Archean (Zerkle et al. 2012, Domagal-Goldman et al. 2008) with important climatic effects (Pavlov et al. 2001, Trainer et al. 2006, Haqq-Misra et al. 2008, Wolf and Toon 2012). We use a 1D coupled photochemical-climate model and a line-by-line radiative transfer model to investigate the climactic and spectral impacts of a fractal hydrocarbon haze on Archean Earth. The haze absorbs significantly at shorter wavelengths and can strongly suppress the Rayleigh scattering tail, a broadband effect that would be remotely detectable at low spectral resolution at wavelengths less than 0.5 μm. Hazes may have a more significant impact on transit transmission spectra. Using the transit transmission radiative transfer model developed by Misra et al. (2014) to generate hazy Archean spectra, we find that even a thin hydrocarbon haze masks the lower atmosphere from the visible into the near infrared where the haze optical depth exceeds unity. The transit transmission spectra we generate for hazy Archean Earth are steeply sloped like the Titan solar occultation spectrum observed by Robinson et al. (2014). Thick hazes can also cool the planet significantly: for example, the thick fractal haze generated around Archean Earth with 0.3% CH4, 1% CO2 and 1 ppm C2H6 cools the planet from roughly 290 K without the haze to below freezing with the haze. Finally, we investigate the impact of host star spectral type on haze formation, comparing the hazes generated around a solar-type star to those generated at an Earth analog planet around the M dwarf AD Leo. Our results indicate hazes around M dwarfs for the same initial atmospheric composition may be thinner due to decreased UV photolysis of methane and other hydrocarbons needed for haze formation. Earthlike

  10. Archean crustal growth of the Imataca complex, Amazonian craton: Evidence from U-Pb-Sm-Nd and Rb-Sr geochronology

    International Nuclear Information System (INIS)

    Tassinari, C.C.G.; Teixeira, W; Nutman, A.P; Szabo, G.; Mondin, M.; Sato, K; Santos, A.P; Siso, C.S

    2001-01-01

    The Archean Imataca Complex (IC), NW Amazonian Craton, forms a ENE-trending, fault-bounded block adjacent to the Paleoproterozoic Maroni-Itacai as magmatic arc (2.2 2.0 Ga) (Tassinari and Macambira, 1999). The IC rocks are complexely deformed, exhibiting elongated and symmetrical domes and thrusts combined with isoclinal folds. Transcurrent faults are also important, like the Guri Fault System - a zone of multiple faulting, shearing and mylonitization along the southeastern edge of the IC. In a pre-Pangean reconstruction using paleomagnetic data from rocks of the African counterpart, the Guri System is contiguous to the Sassandra (Ivory coast) and Zednes (Mauritaine) faults, in agreement also with the comparable geologic evolution between the NW Amazonian and the West Africa cratons, during the Archean and Late-Paleoproterozoic. The IC mainly composed of medium- to high grade quartz-feldspathic paragneiss, exhibits extensive mortar, augen, flaser and mylonitic textures. Calc-alkaline gneiss and granitoid rocks of igneous protolith are also present in the IC, as well as dolomitic marbles, orthopyroxene and magnetite quartzites, and BIFs that include huge ore deposits of Algoma type. Moreover, migmatite injections and anatexis (devoid of metasedimentary components) are widespread in the western part of Complex, the largest migmatite mass centered in Cerro La Ceiba. This paper reports zircon U-Pb SHRIMP, Sm-Nd and Rb-Sr isotopic data of different IC rocks in order to investigate their age and geological evolution within the tectonic framework of the Amazonian Craton (au)

  11. Magmatism and Tectonics in the Meso-Archean Pongola Supergroup, South Africa

    Science.gov (United States)

    Wilson, Allan

    2013-04-01

    The Pongola Supergroup is one of the most extensive and well preserved volcano-sedimentary successions emplaced in a continental setting in the Meso-Archean (c. 2.95 Ga). It contrasts with both the older (Barberton type c.3.5 Ga) and younger (Belingwe type c.2.7 Ga) greenstone belts in southern Africa in that the sequence has not undergone the strong horizontal compressional tectonics typically related to greenstone belt-TTG environments. However, it is appropriate to compare this sequence with rocks of the Barberton greenstone belt by which the final phase of deposition preceded that of the juxtaposed Pongola basin with a relatively small time interval. The Pongola succession, which commenced with the first major magmatic event after the Barberton greenstone belt, overlies granitoids and remnants of greenstone belts in SE South Africa and in SW Swaziland. Formation was not in a continental rift environment but most likely in a marginal epicontinental basin with syn-depositional subsidence in a half-graben fault system in the type area. The Pongola rocks occur in two domains related to a NW-trending central basement high in the Kaapvaal Craton and achieving a maximum thickness of 8 km in the northern areas. The lower section (Nsuze group 3.7 km thick) is made up mainly of lavas and pyroclastic rocks and the upper section (Mozaan Group 4.3 km thick) is aranaceous sediments and argillites with a thick volcanic unit observed in the south-eastern facies. Chemical affinities of the lavas include tholeiite and calc-alkaline over the compositional range of basalt to rhyolite. There is a preponderance of andesites in the compositional array. The preservation of these rocks gives insight into the range of volcanic processes that took place at this stage of Earth history and in some areas it is possible to identify eruptions from a single source over several kilometres, as well as feeder-dyke systems to the lava flows. Simultaneous eruption of contrasting magmas from several

  12. New age (ca. 2970 Ma), mantle source composition and geodynamic constraints on the Archean Fiskenæsset anorthosite complex, SW Greenland

    DEFF Research Database (Denmark)

    Polat, A; Frei, Robert; Scherstén, Anders

    2010-01-01

    The Archean Fiskenæsset Complex, SW Greenland, consists of an association of ca. 550-meter-thick layered anorthosite, leucogabbro, gabbro, and ultramafic rocks (peridotite, pyroxenite, dunite, hornblendite). The complex was intruded by tonalite, trondhjemite, and granodiorite (TTG) sheets (now...... orthogneisses) during thrusting that was followed by several phases of isoclinal folding. The trace element systematics of the Fiskenæsset Complex and associated volcanic rocks are consistent with a supra-subduction zone geodynamic setting. The Fiskenæsset anorthosites, leucogabbros, gabbros and ultramafic...... rocks collectively yield an Sm–Nd errorchron age of 2973 ± 28 Ma (MSWD = 33), with an average initial eNd = + 3.3 ± 0.7, consistent with a long-term depleted mantle source. Regression of Pb isotope data define an age of 2945 ± 36 Ma (MSWD = 44); and the regression line intersects the average growth...

  13. Formation of the Archean crust of the ancient Vodlozero domain (Baltic shield)

    Science.gov (United States)

    Arestova, N. A.; Chekulaev, V. P.; Lobach-Zhuchenko, S. B.; Kucherovskii, G. A.

    2015-03-01

    The available geological, petrological, and isotopic data on Archean rocks of the Baltic shield are used to analyze the formation of the crust of the ancient Vodlozero domain. This made it possible to reveal the succession of endogenic processes in different parts of the domain and correlate them between each other. Several stages of magmatic processes reflecting changes in magma-generation environments are definable in the crust formation. The earliest stages of magmatism (3.24 and 3.13-3.15 Ga) are mostly represented by rocks of the tonalite-trondhjemite-granodiorite association. The next stage of endogenic activity (3020-2900 Ma) was marked by the formation of volcanics of the komatiite-basalt and andesite-dacite associations constituting greenstone belts in marginal parts of the Vodlozero domain and basic dikes accompanied by layered pyroxenite-norite-diorite intrusion in its central part. These basic bodies crossing earlier tonalities were formed in extension settings related to the formation of the mantle plume, which is confirmed by the rock composition. This stage culminated in the formation of trondhjemites at margins of greenstone structure. The next stage of endogenic activity commenced at 2890-2840 Ma by the emplacement of high-magnesian gabbro and diorite dikes in the western margin of the domain, where they cross rocks of the tonalitetrondhjemite association. This stage was marked by the formation of intermediate-acid subvolcanic bodies and dikes as well as basite intrusions including the layered and differentiated Semch intrusion, the largest one in the Vodlozero domain. The stage culminated at approximately 2850 Ma in the emplacement of tonalities of the limited distribution being represented by the Shilos massif in the north of the domain and Shal'skii massif on the eastern shore of Lake Onega. The important stage in the geological history of the Vodlozero domain is the formation of the intracratonic Matkalakhta greenstone belt at approximately 2

  14. Carbon, nitrogen, and sulfur geochemistry of Archean and Proterozoic shales from the Kaapvaal Craton, South Africa

    Science.gov (United States)

    Watanabe, Yumiko; Naraoka, Hiroshi; Wronkiewicz, David J.; Condie, Kent C.; Ohmoto, Hiroshi

    1997-08-01

    The C, N, and S contents and VC and δ 13Cδ 34S values were analyzed for 100 shale samples from ten formations, 3.0 to 2.1 Ga in age, in the central and eastern regions of the Kaapvaal Craton, South Africa. The Kaapvaal shales are characterized by generally low contents of organic C (range 0.06-2.79 wt%, average 0.47 wt%), N (range facies). From the theoretical relationships between the H/C ratios of kerogen and organic C contents of shales, the original C contents of the Archean and Proterozoic shales from the Kaapvaal Craton are estimated to be on average ˜2 wt%. These values are similar to the average organic C content of modern marine sediments. This suggests that the primary organic productivity and the preservation of organic matter in the ocean during the period of 3.0 to 2.1 Ga were similar to those in the Phanerozoic era, provided the flux of clastic sediments to the ocean was similar. This would also imply that the rate of O 2 accumulation in the atmosphere-ocean system, which has equaled the burial rate of organic matter in sediments, has been the same since ˜3.0 Ga. The δ 34S values of bulk-rock sulfides (mostly pyrite) range from +2.7 to +7.4%‰ for seven sulfide-rich samples of ˜2.9 Ga to ˜2.6 Ga. These values are consistent with a suggestion by Ohmoto (1992) and Ohmoto et al. (1993) that most pyrite crystals in Archean shales were formed by bacterial reduction of seawater sulfate with δ 34S values between +2 and +10‰, and that the Archean seawater was sulfate rich. Changes in the δ 13C org values during maturation of kerogen were evaluated with theoretical calculations from the experimental data of Peters et al. (1981) and Lewan (1983), and from the observations by Simoneit et al. (1981) on natural samples. These evaluations suggest that the magnitudes of δ 13C org increase are much less than those estimated by Hayes et al. (1983) and Des Marais et al. (1992), and only about 2 to 3%‰ for the kerogens that decreased their H/C ratios from

  15. Geological and Chemical Factors that Impacted the Biological Utilization of Cobalt in the Archean Eon

    Science.gov (United States)

    Moore, Eli K.; Hao, Jihua; Prabhu, Anirudh; Zhong, Hao; Jelen, Ben I.; Meyer, Mike; Hazen, Robert M.; Falkowski, Paul G.

    2018-03-01

    The geosphere and biosphere coevolved and influenced Earth's biological and mineralogical diversity. Changing redox conditions influenced the availability of different transition metals, which are essential components in the active sites of oxidoreductases, proteins that catalyze electron transfer reactions across the tree of life. Despite its relatively low abundance in the environment, cobalt (Co) is a unique metal in biology due to its importance to a wide range of organisms as the metal center of vitamin B12 (aka cobalamin, Cbl). Cbl is vital to multiple methyltransferase enzymes involved in energetically favorable metabolic pathways. It is unclear how Co availability is linked to mineral evolution and weathering processes. Here we examine important biological functions of Co, as well as chemical and geological factors that may have influenced the utilization of Co early in the evolution of life. Only 66 natural minerals are known to contain Co as an essential element. However, Co is incorporated as a minor element in abundant rock-forming minerals, potentially representing a reliable source of Co as a trace element in marine systems due to weathering processes. We developed a mineral weathering model that indicates that dissolved Co was potentially more bioavailable in the Archean ocean under low S conditions than it is today. Mineral weathering, redox chemistry, Co complexation with nitrogen-containing organics, and hydrothermal environments were crucial in the incorporation of Co in primitive metabolic pathways. These chemical and geological characteristics of Co can inform the biological utilization of other trace metals in early forms of life.

  16. The electrical lithosphere in Archean cratons: examples from Southern Africa

    Science.gov (United States)

    Khoza, D. T.; Jones, A. G.; Muller, M. R.; Webb, S. J.

    2011-12-01

    The southern African tectonic fabric is made up of a number Archean cratons flanked by Proterozoic and younger mobile belts, all with distinctly different but related geological evolutions. The cratonic margins and some intra-cratonic domain boundaries have played major roles in the tectonics of Africa by focusing ascending magmas and localising cycles of extension and rifting. Of these cratons the southern extent of the Congo craton is one of the least-constrained tectonic boundaries in the African tectonic architecture and knowledge of its geometry and in particular the LAB beneath is crucial for understanding geological process of formation and deformation prevailing in the Archean and later. In this work, which forms a component of the hugely successful Southern African MagnetoTelluric Experiment (SAMTEX), we present the lithospheric electrical resistivity image of the southern boundary of the enigmatic Congo craton and the Neoproterozoic Damara-Ghanzi-Chobe (DGC) orogenic belt on its flanks. Magnetotelluric data were collected along profiles crossing all three of these tectonic blocks. The two dimensional resistivity models resulting from inverting the distortion-corrected responses along the profiles all indicate significant lateral variations in the crust and upper mantle structure along and across strike from the younger DGC orogen to the older adjacent craton. The are significant lithospheric thickness variations from each terrane. The The Moho depth in the DGC is mapped at 40 km by active seismic methods, and is also well constrained by S-wave receiver function models. The Damara belt lithosphere, although generally more conductive and significantly thinner (approximately 150 km) than the adjacent Congo and Kalahari cratons, exhibits upper crustal resistive features interpreted to be caused by igneous intrusions emplaced during the Gondwanan Pan-African magmatic event. The thinned lithosphere is consistent with a 50 mW.m-2 steady-state conductive

  17. Application of kinematic vorticity and gold mineralization for the wall rock alterations of shear zone at Dungash gold mining, Central Eastern Desert, Egypt

    Science.gov (United States)

    Kassem, Osama M. K.; Abd El Rahim, Said H.; El Nashar, EL Said R.; AL Kahtany, Kaled M.

    2016-11-01

    The use of porphyroclasts rotating in a flowing matrix to estimate mean kinematic vorticity number (Wm) is important for quantifying the relative contributions of pure and simple shear in wall rocks alterations of shear zone at Dungash gold mine. Furthermore, it shows the relationship between the gold mineralization and deformation and also detects the orientation of rigid objects during progressive deformation. The Dungash gold mine area is situated in an EW-trending quartz vein along a shear zone in metavolcanic and metasedimentary host rocks in the Eastern Desert of Egypt. These rocks are associated with the major geologic structures which are attributed to various deformational stages of the Neoproterozoic basement rocks. We conclude that finite strain in the deformed rocks is of the same order of magnitude for all units of metavolcano-sedimentary rocks. The kinematic vorticity number for the metavolcanic and metasedimentary samples in the Dungash area range from 0.80 to 0.92, and together with the strain data suggest deviations from simple shear. It is concluded that nappe stacking occurred early during the underthrusting event probably by brittle imbrication and that ductile strain was superimposed on the nappe structure during thrusting. Furthermore, we conclude that disseminated mineralization, chloritization, carbonatization and silicification of the wall rocks are associated with fluids migrating along shearing, fracturing and foliation of the metamorphosed wall rocks.

  18. U/Pb (SHRIMP), 207Pb/206Pb, Rb/Sr, Sm/Nd e K/Ar geochronology of granite-greenstone terrains of Gaviao Block: implications for the Proterozoic and Archean evolution of Sao Francisco Craton, Brazil

    International Nuclear Information System (INIS)

    Leal, Luiz Rogerio Bastos

    1998-01-01

    The Gaviao Block (GB) in the northern portion of the Sao Francisco Craton-Northeast of Brazil, constitutes one of the oldest Archean fragments of the South American Platform Archean crust. GB underwent several events of juvenile accretion and reworking of continental crust along its evolutionary history, notably between the Archean and the Paleoproterozoic. 207 Pb/ 206 Pb isotopic analyses were carried out in two zircons populations from strongly migmatized TTG terranes found in the proximity of Brumado: the first population (7 crystals) is taken as representative of the crystallization period of the TTG terranes at 3300 ± 45 Ma; the second (2 crystals) represents the age of the first even of metamorphism/migmatization at 2910 ± 10 Ma. 207 Pb/ 206 Pb analyses in zircons from an outcrop of non-migmatized TTG in the area yielded a 3202 ± 15 Ma age (4 crystals), interpreted to be the crystallization period of the gneiss protolith. Sm/Nd analyses on the TTG rocks of the Brumado region yielded T DM model ages varying between 3.26 and 3.36 Ga and ε Nd (t) between -3.5 and +0.7. These data suggest the occurrence of juvenile accretions to the continental crust during the Archean, with differential involvement of crustal materials. The geochemical data of rare earth elements corresponding to the TTG terranes revealed moderate LRRE contents (La N =83,5), low HREE contents (La N =2,5) and a fairly fractionated pattern (La/Yb) N =34, besides lack of negative Eu anomaly, showing that these rocks have similar compositions to those TTG terranes of cratonic continents, as well as some Archean rocks from CSF (e.g. Sete Voltas, Boa Vista). Finally, the youngest ages present in GB rocks (ca. 1.2-0.45 Ga) represent the role played by tectono thermal events, which produced partial or total rejuvenation of the Rb/Sr and K/Ar isotopic systems during the Espinhaco and Brasiliano cycles. In particular, K/Ar ages illustrate the effect of younger regional cooling episodes related to the

  19. Rock fragmentation

    Energy Technology Data Exchange (ETDEWEB)

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

    1976-01-01

    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)

  20. Short-Wavelength Infrared (SWIR) spectroscopy of low-grade metamorphic volcanic rocks of the Pilbara Craton

    NARCIS (Netherlands)

    Abweny, Mohammad S.; van Ruitenbeek, Frank J A; de Smeth, Boudewijn; Woldai, Tsehaie; van der Meer, Freek D.; Cudahy, Thomas; Zegers, Tanja; Blom, Jan Kees; Thuss, Barbara

    This paper shows the results of Short-Wavelength Infrared (SWIR) spectroscopy investigations of volcanic rocks sampled from low-grade metamorphic greenstone belts of the Archean Pilbara Craton in Western Australia. From the reflectance spectra a range of spectrally active minerals were identified,

  1. carbonaceous phyllite/graphitic schist in the Archean Kundarkocha

    Indian Academy of Sciences (India)

    rocks of noble metals (Meyers et al. 1990). Such complexes host gold deposits in North–East. Russia (Natalka, Mayskoe ..... carbonic phases using Laser Raman Spectrometry ... Graphite was formed by the reaction between CH4 and CO2.

  2. Characterization of crystalline rocks in the Lake Superior region, USA: implications for nuclear waste isolation

    International Nuclear Information System (INIS)

    Sood, M.K.; Flower, M.F.J.; Edgar, D.E.

    1984-01-01

    The Lake Superior region (Wisconsin, the Upper Peninsula of Michigan, and Minnesota) contains 41 Precambrian crystalline rock complexes comprising 64 individual but related rock bodies with known surface exposures. Each complex has a map area greater than 78 km 2 . About 54% of the rock complexes have areas of up to 500 km 2 , 15% fall between 500 km 2 and 1000 km 2 , 19% lie between 1000 km 2 and 2500 km 2 , and 12% are over 2500 km 2 . Crystalline rocks of the region vary widely in composition, but they are predominantly granitic. Repeated thermo-tectonic events have produced early Archean gneisses, migmatites, and amphibolites with highly tectonized fabrics that impart a heterogeneous and anisotropic character to the rocks. Late Archean rocks are usually but not invariably gneissose and migmatitic. Proterozoic rocks of the region include synorogenic (foliated) granitic rocks, anorogenic (non-foliated) granites, and the layered gabbro-anorthosite-troctolite intrusives of the rift-related Keweenawan igneous activity. Compared with the Archean rocks of the region, the Proterozoic bodies generally lack highly tectonized fabrics and have more definable contacts where visible. Anorogenic intrusions are relatively homogeneous and isotropic. On the basis of observed geologic characteristics, postorogenic and anorogenic crystalline rock bodies located away from recognized tectonic systems have attributes that make them relatively more desirable as a possible site for a nuclear waste repository in the region. This study was conducted at Argonne National Laboratory under the sponsorship of the US Department of Energy through the Office of Crystalline Repository Development at Battelle Memorial Institute, Columbus, Ohio. 84 references, 4 figures, 3 tables

  3. Characterization of crystalline rocks in the Lake Superior region, USA: implications for nuclear waste isolation

    International Nuclear Information System (INIS)

    Sood, M.K.; Edgar, D.E.; Flower, M.F.J.

    1984-01-01

    The Lake Superior region (Wisconsin, the Upper Peninsula of Michigan, and Minnesota) contains 41 Precambrian crystalline (medium- to coarse-grained igneous and high-grade metamorphic) rock complexes comprising 64 individual but related rock bodies with known surface exposures. Each complex has a map area greater than 78 km 2 . About 54% of the rock complexes have areas of up to 500 km 2 , 15% fall between 500 km 2 and 1000 km 2 , 19% lie between 1000 km 2 and 2500 km 2 , and 12% are over 2500 km 2 . Crystalline rocks of the region vary widely in composition, but they are predominantly granitic. Repeated thermo-tectonic events have produced early Archean gneisses, migmatites, and amphibolites with highly tectonized fabrics that impart a heterogeneous and anisotropic character to the rocks. Late Archean rocks are usually but not invariably gneissose an migmatitic. Proterozoic rocks of the region include synorogenic (foliated) granitic rocks, anorogenic (nonfoliated) granites, and the layered gabbro-anorthosite-troctolite intrusives of the rift-related Keweenawan igneous activity. Compared with the Archean rocks of the region, the Proterozoic bodies generally lack highly tectonized fabrics and have more definable contacts where visible. Anorogenic intrusions are relatively homogeneous and isotropic. On the basis of observed geologic characteristics, postorogenic and anorogenic crystalline rock bodies located away from recognized tectonic systems have attributes that make them relatively more desirable as a possible site for a nuclear waste repository in the region. This study was conducted at Argonne National Laboratory under the sponsorship of the US Department of Energy through the Office of Crystalline Repository Development at Battelle Memorial Institute, Columbus, Ohio

  4. Assessing the effects of ultraviolet radiation on the photosynthetic potential in Archean marine environments

    Science.gov (United States)

    Avila-Alonso, Dailé; Baetens, Jan M.; Cardenas, Rolando; de Baets, Bernard

    2017-07-01

    In this work, the photosynthesis model presented by Avila et al. in 2013 is extended and more scenarios inhabited by ancient cyanobacteria are investigated to quantify the effects of ultraviolet (UV) radiation on their photosynthetic potential in marine environments of the Archean eon. We consider ferrous ions as blockers of UV during the Early Archean, while the absorption spectrum of chlorophyll a is used to quantify the fraction of photosynthetically active radiation absorbed by photosynthetic organisms. UV could have induced photoinhibition at the water surface, thereby strongly affecting the species with low light use efficiency. A higher photosynthetic potential in early marine environments was shown than in the Late Archean as a consequence of the attenuation of UVC and UVB by iron ions, which probably played an important role in the protection of ancient free-floating bacteria from high-intensity UV radiation. Photosynthetic organisms in Archean coastal and ocean environments were probably abundant in the first 5 and 25 m of the water column, respectively. However, species with a relatively high efficiency in the use of light could have inhabited ocean waters up to a depth of 200 m and show a Deep Chlorophyll Maximum near 60 m depth. We show that the electromagnetic radiation from the Sun, both UV and visible light, could have determined the vertical distribution of Archean marine photosynthetic organisms.

  5. Rock Art

    Science.gov (United States)

    Henn, Cynthia A.

    2004-01-01

    There are many interpretations for the symbols that are seen in rock art, but no decoding key has ever been discovered. This article describes one classroom's experiences with a lesson on rock art--making their rock art and developing their own personal symbols. This lesson allowed for creativity, while giving an opportunity for integration…

  6. A Sr-isotopic comparison between thermal waters, rocks, and hydrothermal calcites, Long Valley caldera, California

    Science.gov (United States)

    Goff, F.; Wollenberg, H.A.; Brookins, D.C.; Kistler, R.W.

    1991-01-01

    The 87Sr/86Sr values of thermal waters and hydrothermal calcites of the Long Valley caldera geothermal system are more radiogenic than those of young intracaldera volcanic rocks. Five thermal waters display 87Sr/86Sr of 0.7081-0.7078 but show systematically lighter values from west to east in the direction of lateral flow. We believe the decrease in ratio from west to east signifies increased interaction of deeply circulating thermal water with relatively fresh volcanic rocks filling the caldera depression. All types of pre-, syn-, and post-caldera volcanic rocks in the west and central caldera have (87Sr/86Sr)m between about 0.7060 and 0.7072 and values for Sierra Nevada granodiorites adjacent to the caldera are similar. Sierran pre-intrusive metavolcanic and metasedimentary rocks can have considerably higher Sr-isotope ratios (0.7061-0.7246 and 0.7090-0.7250, respectively). Hydrothermally altered volcanic rocks inside the caldera have (87Sr/86Sr)m slightly heavier than their fresh volcanic equivalents and hydrothermal calcites (0.7068-0.7105) occupy a midrange of values between the volcanic/plutonic rocks and the Sierran metamorphic rocks. These data indicate that the Long Valley geothermal reservoir is first equilibrated in a basement complex that contains at least some metasedimentary rocks. Reequilibration of Sr-isotope ratios to lower values occurs in thermal waters as convecting geothermal fluids flow through the isotopically lighter volcanic rocks of the caldera fill. ?? 1991.

  7. Geological Sulfur Isotopes Indicate Elevated OCS in the Archean Atmosphere, Solving the Faint Young Sun Paradox

    DEFF Research Database (Denmark)

    Ueno, Yuichiro; Johnson, Matthew Stanley; Danielache, Sebastian Oscar

    2009-01-01

    Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of 32SO2, 33SO2, and 34SO2 and use them to interpret the geological re......-rich, reducing Archean atmosphere. The radiative forcing, due to this level of OCS, is able to resolve the faint young sun paradox. Further, the decline of atmospheric OCS may have caused the late Archean glaciation....

  8. Geochronology of the basement rocks, Amazonas Territory, Venezuela and the tectonic evolution of the western Guiana Shield

    Energy Technology Data Exchange (ETDEWEB)

    Gaudette, H E; Olszewski, Jr, W J

    1985-01-01

    The Amazonas Territory of Venezuela is a large area of Precambrian basement rocks overlain in some locales by the supracrustal sedimentary and volcanic rocks of the Roraima Formation. The basement rocks are medium to high grade gneisses with both igneous and sedimentary protoliths, plutonic rocks ranging in composition from granite to tonalite, and meta-volcanic rocks. Rb-Sr whole rock, and U-Pb isotopic analyses of zircons indicate a period of medium to high grade metamorphism and intrusion from 1860 to 1760 Ma. Post-tectonic plutonic activity continued to 1550 Ma. The volcanic rocks of the Roraima Formation in Venezuela give an age of 1746 Ma comparable to volcanic rocks of the Roraima Formation in other parts of the Guiana Shield. The ages and distribution of the basement rocks suggest the presence of a tectonic zone, approximately coincident with the Venezuelan-Colombian border, representing an active orogenic boundary between distinct tectonic provinces. The rocks to the northeast of this zone are part of the Trans-Amazonian of the Guiana Shield, while to the southwest and in adjacent Brazil and Colombia, new younger continental crust has been developed and cratonized. We suggest a model of collision and subduction followed by a chan0140n tectonic style to extensional-vertical to produce the basement rocks of the western Guiana Shield in the Amazonas Territory. (Auth.). 20 refs.; 13 figs.; 2 tabs.

  9. Evolution of the Dharwar Craton: a terrain of early Archean crustal stability, long term orogenic cycles and large scale palaeobiological activity

    International Nuclear Information System (INIS)

    Srinivasan, R.; Naqvi, S.M.

    1988-01-01

    Traceable history of the Dharwar Craton goes back to approximately 3400 m.y. old tonalitic to trondhjemitic fundamental gneiss whose REE composition indicates its derivation from a preexisting basalt which apparently had very short time of crustal residence. The fundamental gneiss is preserved only as rare relicts in the vast gneissic complex of the Indian Peninsula (the Peninsular Gneiss), and as pebbles in the conglomerates of the Archean Dharwar sequence. Study of these relicts, shows evidence of a deformation episode prior to the deposition of the high- and low-grade Dharwar supracrustal sequence. The Dharwar supracrustal sequence is briefly described. Geochemistry of the volcanic and sedimentary rocks of the Dharwar supracrustal belts are examined

  10. New Sm/Nd and U/Pb geochronological constraints of the Archean to neoproterozoic evolution of the Amparo basement complex of the Central Ribeira Belt, Southeastern Brazil

    International Nuclear Information System (INIS)

    Fetter, A.H.; Hackspacher, P.C.; Ebbert, H.D; Dantas, E.L; Costa, A.C.D. da

    2001-01-01

    The Amparo Basement Complex is a distinctive collage of migmatitic tronjhemitetonalite- granodiorite (TTG) orthogneisses that represents the older basement exposures within the Central Ribeira Belt, a Late Neoproterozoic (ca. 600 Ma) collisional belt in southeastern Brazil. These basement gneisses are overlain by Mesoproterozoic to Neoproterozoic supracrustal sequences, and intruded by Neoproterozoic collisional granitoids. Pioneering Rb/Sr, Pb/Pb and K/Ar geochronological studies of the Amparo Complex, e.g. (Wernick et al., 1981; Wernick and Oliveira, 1986; Arthur, 1988; Tassinari, 1988; Campos Neto, 1991) provided some initial insights into the antiquity and geologic evolution of the complex, but little about the crustal evolution of the constituent gneisses. Furthermore, the susceptibility of these systems to partial isotopic resetting, left some doubt about the timing and true number of geologic events recorded by these polydeformed rocks. Recent Sm/Nd whole rock (Dantas et al., 2000) and new U/Pb single crystal zircon and monazite data obtained from the Amparo Complex, however, now furnish information on the crustal growth history of the basement and provide precise age constraints on the timing of events related to the geologic evolution of the complex. Based on these new data, it appears that the oldest rocks within the complex are polymigmatized tronjhemitic gneisses located near the town of Amparo. The oldest phase of this migmatite yields a U/Pb zircon age of 3,024 +/- 9 Ma. Sm/Nd data from this locale yields a Nd T(DM) model age of 3.28 Ga suggesting that the genesis of this crustal unit involved some input from yet older crust. Data from banded tonalitic gneisses collected ca. 50 km south of Amparo indicate that subsequent Archean crustal growth around the older core occurred around 2.77 Ga (U/Pb zircon age of 2,772 +/- 26 Ma. A Nd T(DM) model age of 3.02 Ga obtained from these tonalites also indicate enrichment from older crustal sources during their

  11. Archean and proterozoic continental crust in South America: Main building events

    International Nuclear Information System (INIS)

    Fuck, R.A; Brito Neves, B.B; Pimentel, M.M

    2001-01-01

    Available geochronological data reveal that the first building blocks of the South American continental crust were set up in the early Paleoarchean, ca. 3.4-3.5 Ga ago, although the presence of components as old as 3.7 Ga is indicated by Nd TDM model ages. The oldest rocks so far recognized are exposed in northeast Brazil and Uruguay. In the Sao Jose do Campestre block, Rio Grande do Norte, 3.45 Ga old tonalite, migmatized and intruded by granitoids between 3.3 and 3.0 Ga, is part of the basement to the Borborema Province (Dantas et al. 1998). In Bahia 3.42 Ga old tonalitic grey gneisses of Sete Voltas, Boa Vista, and Mairi form the basement of the Gaviao block, within the core of the Sao Francisco Craton (Nutman and Cordani, 1993, Martin et al., 1997). The Paleoarchean TTG suites as well as greenstone remnants of unknown age were involved in crust accretion events between 3.1 and 3.3 Ga ago (Teixeira et al. 2000 and references therein), which are also recorded in Campo Belo and Uaua (Teixeira et al., 1998, Oliveira et al., 1999), as attested by TTG intrusions and the ca. 3.1 Ga Pium-hi greenstone belt of W Minas Gerais (Machado and Schrank 1989). Microcontinents then formed were involved in deformation, metamorphism, and migmatization around 2.8-3.0 Ga ago, probably during amalgamation events. Widespread granite-greenstone associations in the Quadrilatero Ferrifero and other areas represent new crust built during the very important Neoarchean Rio das Velhas cycle, ca. 2.7-2.8 Ga ago (Machado and Carneiro 1992, Machado et al. 1992). Layered mafic-ultramafic and granite intrusions ca. 2.5-2.7 Ga old are recorded all over the Sao Francisco Craton, including the high-grade terrain of southern Bahia, formed during the late Archean Jequie Cycle (Teixeira et al. 2000 and references therein). Similar intrusions are recorded in many basement areas within Neoproterozoic fold belts (au)

  12. 'Escher' Rock

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] Chemical Changes in 'Endurance' Rocks [figure removed for brevity, see original site] Figure 1 This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a rock dubbed 'Escher' on the southwestern slopes of 'Endurance Crater.' Scientists believe the rock's fractures, which divide the surface into polygons, may have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the rock's formation dried up. A third possibility is that much later, after the rock was formed, and after the crater was created, the rock became wet once again, then dried up and developed cracks. Opportunity has spent the last 14 sols investigating Escher, specifically the target dubbed 'Kirchner,' and other similar rocks with its scientific instruments. This image was taken on sol 208 (Aug. 24, 2004) by the rover's panoramic camera, using the 750-, 530- and 430-nanometer filters. The graph above shows that rocks located deeper into 'Endurance Crater' are chemically altered to a greater degree than rocks located higher up. This chemical alteration is believed to result from exposure to water. Specifically, the graph compares ratios of chemicals between the deep rock dubbed 'Escher,' and the more shallow rock called 'Virginia,' before (red and blue lines) and after (green line) the Mars Exploration Rover Opportunity drilled into the rocks. As the red and blue lines indicate, Escher's levels of chlorine relative to Virginia's went up, and sulfur down, before the rover dug a hole into the rocks. This implies that the surface of Escher has been chemically altered to a greater extent than the surface of Virginia. Scientists are still investigating the role water played in influencing this trend. These data were taken by the rover's alpha particle X-ray spectrometer.

  13. The Archean komatiite-hosted, PGE-bearing Ni-Cu sulfide deposit at Vaara, eastern Finland: evidence for assimilation of external sulfur and post-depositional desulfurization

    Science.gov (United States)

    Konnunaho, J. P.; Hanski, E. J.; Bekker, A.; Halkoaho, T. A. A.; Hiebert, R. S.; Wing, B. A.

    2013-12-01

    Archean komatiites host important resources of Ni, Cu, Co, and PGE, particularly in Western Australia and Canada. In Finland, several small, low-grade sulfide deposits have been found in komatiites, including the ca. 2.8 Ga Vaara deposit in the Archean Suomussalmi greenstone belt. It occurs in the central part of the serpentinized olivine cumulate zone of a komatiitic extrusive body and is composed of disseminated interstitial sulfides consisting of pyrite, pentlandite, millerite, violarite, and chalcopyrite accompanied by abundant magnetite. Although currently subeconomic, the mineralization is interesting due to the very high chalcophile element contents of the sulfide fraction (38 wt% Ni, 3.4 wt% Cu, 0.7 wt% Co, 22.4 ppm Pd, and 9.5 ppm Pt). The sulfides occur in relatively Cr-poor olivine cumulates suggesting involvement of a chromite-undersaturated magma. The parental magma was an Al-undepleted komatiite with an estimated MgO content of at least 24 wt%. In contrast to the common komatiite types in the eastern Finland greenstone belts, the Vaara rocks are moderately enriched in LREE relative to MREE, suggesting that crustal contamination played an important role in the genesis of the Vaara deposit. Multiple sulfur isotope data reveal considerable mass-independent sulfur isotope fractionation both in country rock sedimentary sulfides (Δ33S ranges from -0.50 to +2.37 ‰) and in the Vaara mineralization (Δ33S ranges from +0.53 to +0.66 ‰), which provides strong evidence for incorporation of crustal sulfur. Extensive replacement of interstitial sulfides by magnetite and the presence of millerite- and violarite-bearing, pyrrhotite-free sulfide assemblages indicate significant post-magmatic, low-temperature hydrothermal oxidation of the primary magmatic pyrrhotite-pentlandite-chalcopyrite assemblages and associated sulfur loss that led to a significant upgrading of the original metal tenors of the Vaara deposit.

  14. Constraining Δ33S signatures of Archean seawater sulfate with carbonate-associated sulfate

    Science.gov (United States)

    Peng, Y.; Bao, H.; Bekker, A.; Hofmann, A.

    2017-12-01

    Non-mass dependent sulfur isotope deviation of S-bearing phases in Archean sedimentary strata, and expressed as Δ33S, has a consistent pattern, i.e., sulfide (pyrite) predominantly bear positive Δ33S values, while Paleoarchean sulfate (barite) has negative Δ33S values. This pattern was later corroborated by observations of negative Δ33S values in Archean volcanogenic massive sulfide deposits and negative Δ33S values in early diagenetic nodular pyrite with a wide range of δ34S values, which is thought to be due to microbial sulfate reduction. These signatures have provided a set of initial conditions for a mechanistic interpretation at physical chemistry level. Unlike the younger geological times when large bodies of seawater evaporite deposits are common, to expand seawater sulfate records, carbonate-associated sulfate (CAS) was utilized as a proxy for ancient seawater sulfate. CAS extracted from the Archean carbonates carries positive Δ33S values. However, CAS could be derived from pyrite oxidation following exposure to modern oxidizing conditions and/or during laboratory extraction procedures. It is, therefore, important for us understanding context of the overall early earth atmospheric condition to empirically confirm whether Archean seawater sulfate was generally characterized by negative Δ33S signatures. Combined δ18O, Δ17O, δ34S, and Δ33S analyses of sequentially extracted water-leachable sulfate (WLS) and acid-leachable sulfate (ALS = CAS) and δ34S and Δ33S analyses of pyrite can help to identify the source of extracted sulfate. We studied drill-core samples of Archean carbonates from the 2.55 Ga Malmani and Campell Rand supgroups, South Africa. Our preliminary results show that 1) neither WLS nor ALS were extracted from samples with extremely low pyrite contents (less than 0.05 wt.%); 2) extractable WLS and ALS is present in samples with relatively high pyrite contents (more than 1 wt.%), and that δ34S and Δ33S values of WLS, ALS, and

  15. Diversity in the Archean Biosphere: New Insights from NanoSIMS

    Science.gov (United States)

    Oehler, Dorothy Z.; Robert, François; Walter, Malcolm R.; Sugitani, Kenichiro; Meibom, Anders; Mostefaoui, Smail; Gibson, Everett K.

    2010-05-01

    The origin of organic microstructures in the ˜3 Ga Farrel Quartzite is controversial due to their relatively poor state of preservation, the Archean age of the cherts in which they occur, and the unusual spindle-like morphology of some of the forms. To provide more insight into the significance of these microstructures, nano-scale secondary ion mass spectrometry (NanoSIMS) maps of carbon, nitrogen, sulfur, silicon, and oxygen were obtained for spheroidal and spindle-shaped constituents of the Farrel Quartzite assemblage. Results suggest that the structures are all bona fide ˜3 Ga microfossils. The spindles demonstrate an architecture that is remarkable for 3 Ga organisms. They are relatively large, robust, and morphologically complex. The NanoSIMS element maps corroborate their complexity by demonstrating an intricate, internal network of organic material that fills many of the spindles and extends continuously from the body of these structures into their spearlike appendages. Results from this study combine with previous morphological and chemical analyses to argue that the microstructures in the Farrel Quartzite comprise a diverse assemblage of Archean microfossils. This conclusion adds to a growing body of geochemical, stromatolitic, and morphological evidence that indicates the Archean biosphere was varied and well established by at least ˜3 Ga. Together, the data paint a picture of Archean evolution that is one of early development of morphological and chemical complexity. The evidence for Archean evolutionary innovation may augur well for the possibility that primitive life on other planets could adapt to adverse conditions by ready development of diversity in form and biochemistry.

  16. Recreating Rocks

    DEFF Research Database (Denmark)

    Posth, Nicole R

    2008-01-01

    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....

  17. Archean crustal evolution in the central Minto block, northern Quebec

    Energy Technology Data Exchange (ETDEWEB)

    Skulski, T; Percival, J A; Stern, R A [Geological Survey of Canada, Ottawa, ON (Canada)

    1997-12-31

    The central Minto block contains three volcano-sedimentary successions. Near Lake Qalluviartuuq, an isotopically primitive ({sup 2.83} {sup Ga}{epsilon}{sub Nd} +3.8 to +2.3) 2.83 Ga volcano-plutonic sequence comprises depleted tholeiitic basalts, anorthositic gabbro, and diorite-granodiorite that is unconformably overlain by <2.77 Ga conglomerates. Overlying the conglomerate is a more evolved ({sup 2.76} {sup Ga}{epsilon}{sub Nd} +1.8) calc-alkaline sequence of pillow basalts, andesites, and peridotite cut by 2.73 Ga diorite. To the west, and in inferred tectonic contact, the sediment-dominated Kogaluc sequence includes both isotopically evolved calc-alkaline rocks ({sup 2.76} {sup Ga}{epsilon}{sub Nd} +1.6 to -0.1) including <2.76 Ga rhyolitic tuff, pillowed andesites, and 2.76 Ga quartz-feldspar porphyry, and less abundant, depleted tholeiitic basalts (2.76 GaF-Nd +2.4). These are interlain with sedimentary rocks including banded iron-formation, quartzite, and metagreywacke. Calc-alkaline batholiths include 2.78 Ga pyroxene-bearing intermediate and felsic plutons ({sup 2.78Ga}{epsilon}{sub Nd} <+2.7) and younger, peraluminous tonalites ({epsilon}{sub Nd} <+1.3). Late, 2.73 Ga peraluminous granitoids are isotopically evolved ({sup 2.725Ga}{epsilon}{sub Nd} - 1. 6). (author). 19 refs., 4 tabs., 5 figs.

  18. Finite-strain analysis of Metavolcano-sedimentary rocks at Gabel El Mayet area, Central Eastern Desert, Egypt

    Science.gov (United States)

    Kassem, Osama M. K.; Abd El Rahim, Said H.

    2010-09-01

    Finite strain was estimated in the metavolcano-sedimentary rocks, which surround by serpentinites of Gabel El Mayet area. Finite strain shows a relationship to nappe contacts between the metavolcano-sedimentary rocks and serpentinite and sheds light on the nature of the subhorizontal foliation typical for the Gable Mayet shear zone. We used the Rf/ ϕ and Fry methods on feldspar porphyroclasts and mafic grains from 10 metasedimentary and six metavolcanic samples in Gabel El Mayet region. Our finite-strain data show that the metavolcano-sedimentary rocks were moderately deformed and axial ratios in the XZ section range from 1.9 to 3.9. The long axes of the finite-strain ellipsoids trend W/WNW in the north and W/WSW in the south of the Gabel El Mayet shear zone. Furthermore, the short axes are subvertical to a subhorizontal foliation. The strain magnitudes increase towards the tectonic contacts between the metavolcano-sedimentary rocks and serpentinite. The data indicate oblate strain symmetry in the metavolcano-sedimentary rocks. Hence, our strain data also indicate flattening strain. We assume that the metasedimentary and metavolcanics rocks have similar deformation behaviour. The fact that finite strain accumulated during the metamorphism indicates that the nappe contacts formed during the accumulation of finite strain and thus during thrusting. We conclude that the nappe contacts formed during progressive thrusting under brittle to semi-brittle deformation conditions by simple shear and involved a component of vertical shortening, which caused the subhorizontal foliation in the Gabel El Mayet shear zone.

  19. Art Rocks with Rock Art!

    Science.gov (United States)

    Bickett, Marianne

    2011-01-01

    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…

  20. Rock Physics

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2017-01-01

    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...

  1. Archean crustal evolution in the central Minto block, northern Quebec

    International Nuclear Information System (INIS)

    Skulski, T.; Percival, J.A.; Stern, R.A.

    1996-01-01

    The central Minto block contains three volcano-sedimentary successions. Near Lake Qalluviartuuq, an isotopically primitive ( 2.83 Ga ε Nd +3.8 to +2.3) 2.83 Ga volcano-plutonic sequence comprises depleted tholeiitic basalts, anorthositic gabbro, and diorite-granodiorite that is unconformably overlain by 2.76 Ga ε Nd +1.8) calc-alkaline sequence of pillow basalts, andesites, and peridotite cut by 2.73 Ga diorite. To the west, and in inferred tectonic contact, the sediment-dominated Kogaluc sequence includes both isotopically evolved calc-alkaline rocks ( 2.76 Ga ε Nd +1.6 to -0.1) including 2.78Ga ε Nd Nd 2.725Ga ε Nd - 1. 6). (author). 19 refs., 4 tabs., 5 figs

  2. Rocking pneumonia

    OpenAIRE

    Rijkers, Ger T.; Rodriguez Gomez, Maria

    2017-01-01

    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 ...

  3. The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth.

    Science.gov (United States)

    Arney, Giada; Domagal-Goldman, Shawn D; Meadows, Victoria S; Wolf, Eric T; Schwieterman, Edward; Charnay, Benjamin; Claire, Mark; Hébrard, Eric; Trainer, Melissa G

    2016-11-01

    Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8-2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ∼ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7-2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO 2 . Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets. Key Words: Haze-Archean Earth-Exoplanets-Spectra-Biosignatures-Planetary habitability

  4. Albedo and heat transport in 3-D model simulations of the early Archean climate

    Directory of Open Access Journals (Sweden)

    H. Kienert

    2013-08-01

    Full Text Available At the beginning of the Archean eon (ca. 3.8 billion years ago, the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun paradox" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-D model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. In order to do so, we have appropriately modified an intermediate complexity climate model that couples a statistical-dynamical atmosphere model (involving parameterizations of the dynamics to an ocean general circulation model and a thermodynamic-dynamic sea-ice model. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth". We find a reduction in meridional heat transport compared to today, which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterization of the ice-albedo feedback for 1-D model simulations of the early Archean and thus the faint young Sun problem.

  5. Reconciling "Whiffs" of O2 with the Archean MIF S Record: Insights from Sulfide Oxidation Experiments

    Science.gov (United States)

    Johnson, A.; Reinhard, C. T.; Romaniello, S. J.; Greaney, A. T.; Garcia-Robledo, E.; Revsbech, N. P.; Canfield, D. E.; Lyons, T. W.; Anbar, A. D.

    2016-12-01

    The Archean-Proterozoic transition is marked by the first appreciable accumulation of O2 in Earth's oceans and atmosphere at 2.4 billion years ago (Ga). However, this Great Oxidation Event (GOE) is not the first evidence for O2 in Earth's surface environment. Paleoredox proxies preserved in ancient marine shales (Mo, Cr, Re, U) suggest transient episodes of oxidative weathering before the GOE, perhaps as early as 3.0 Ga. One marine shale in particular, the 2.5 Ga Mount McRae Shale of Western Australia, contains a euxinic interval with Mo enrichments up to 50 ppm. This enrichment is classically interpreted as the result of oxidative weathering of sulfides on the continental surface. However, prior weathering models based on experiments suggested that sulfides require large amounts of O2 [>10-4 present atmospheric level (PAL) pO2] to produce this weathering signature, in conflict with estimates of Archean pO2 from non-mass-dependent (NMD) sulfur isotope anomalies (molybdenite from 3 - 700 nM O2 (equivalent at equilibrium to 10-5 - 10-3 PAL) to measure oxidation kinetics as a function of the concentration of dissolved O2. We measured rates by injecting oxygenated water at a steady flow rate and monitoring dissolved O2 concentrations with LUMOS sensors. Our data extend the O2 range explored in pyrite oxidation experiments by three orders of magnitude and provide the first rates for molybdenite oxidation at O2 concentrations potentially analogous to those characteristic of the Archean atmosphere. Our results show that pyrite and molybdenite oxidize significantly more rapidly at lower O2 levels than previously thought. As a result, our revised weathering model demonstrates that the Mo enrichments observed in late Archean marine shales are potentially attainable at extremely low atmospheric pO2 values (e.g., <10-5 PAL), reconciling large sedimentary Mo enrichments with co-occurring NMD sulfur isotope anomalies.

  6. Organic compounds in fluid inclusions of Archean quartz-Analogues of prebiotic chemistry on early Earth.

    Science.gov (United States)

    Schreiber, Ulrich; Mayer, Christian; Schmitz, Oliver J; Rosendahl, Pia; Bronja, Amela; Greule, Markus; Keppler, Frank; Mulder, Ines; Sattler, Tobias; Schöler, Heinz F

    2017-01-01

    The origin of life is still an unsolved mystery in science. Hypothetically, prebiotic chemistry and the formation of protocells may have evolved in the hydrothermal environment of tectonic fault zones in the upper continental crust, an environment where sensitive molecules are protected against degradation induced e.g. by UV radiation. The composition of fluid inclusions in minerals such as quartz crystals which have grown in this environment during the Archean period might provide important information about the first organic molecules formed by hydrothermal synthesis. Here we present evidence for organic compounds which were preserved in fluid inclusions of Archean quartz minerals from Western Australia. We found a variety of organic compounds such as alkanes, halocarbons, alcohols and aldehydes which unambiguously show that simple and even more complex prebiotic organic molecules have been formed by hydrothermal processes. Stable-isotope analysis confirms that the methane found in the inclusions has most likely been formed from abiotic sources by hydrothermal chemistry. Obviously, the liquid phase in the continental Archean crust provided an interesting choice of functional organic molecules. We conclude that organic substances such as these could have made an important contribution to prebiotic chemistry which might eventually have led to the formation of living cells.

  7. Re-Os systematics of komatiites and komatiitic basalts at Dundonald Beach, Ontario, Canada: Evidence for a complex alteration history and implications of a late-Archean chondritic mantle source

    Science.gov (United States)

    Gangopadhyay, Amitava; Sproule, Rebecca A.; Walker, Richard J.; Lesher, C. Michael

    2005-11-01

    Osmium isotopic compositions, and Re and Os concentrations have been examined in one komatiite unit and two komatiitic basalt units at Dundonald Beach, part of the 2.7 Ga Kidd-Munro volcanic assemblage in the Abitibi greenstone belt, Ontario, Canada. The komatiitic rocks in this locality record at least three episodes of alteration of Re-Os elemental and isotope systematics. First, an average of 40% and as much as 75% Re may have been lost due to shallow degassing during eruption and/or hydrothermal leaching during or immediately after emplacement. Second, the Re-Os isotope systematics of whole rock samples with 187Re/ 188Os ratios >1 were reset at ˜2.5 Ga, possibly due to a regional metamorphic event. Third, there is evidence for relatively recent gain and loss of Re in some rocks. Despite the open-system behavior, some aspects of the Re-Os systematics of these rocks can be deciphered. The bulk distribution coefficient for Os (D Ossolid/liquid) for the Dundonald rocks is ˜3 ± 1 and is well within the estimated D values obtained for komatiites from the nearby Alexo area and stratigraphically-equivalent komatiites from Munro Township. This suggests that Os was moderately compatible during crystal-liquid fractionation of the magmas parental to the Kidd-Munro komatiitic rocks. Whole-rock samples and chromite separates with low 187Re/ 188Os ratios (Gorgona Island, arc-related rocks and present-day ocean island basalts. This suggests that the Kidd-Munro komatiites sampled a late-Archean mantle source region that was significantly more homogeneous with respect to Re/Os relative to most modern mantle-derived rocks.

  8. Source rock

    Directory of Open Access Journals (Sweden)

    Abubakr F. Makky

    2014-03-01

    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.

  9. The effects of bacteria on crystalline rock

    International Nuclear Information System (INIS)

    Brown, D.A.

    1994-01-01

    Many reactions involving inorganic minerals at water-rock interfaces have now been recognized to be bacterially mediated; these reactions could have a significant effect in the excavation of vaults for toxic and radioactive waste disposal. To investigate the role that bacteria play in the natural aqueous environment of crystalline rock the microbial growth factors of nutrition, energy and environment are described. Microbial activity has been investigated in Atomic Energy of Canada's Underground Research Laboratory (URL), situated in the Archean granitic Lac du Bonnet Batholith, Winnipeg, Manitoba. Faults, initiated in the Early Proterozoic, and later-formed fractures, provide ground-water pathways. Planktonic bacteria, free-swimming in the groundwater, have been observed in over 100 underground borehole samples. The number of bacteria varied from 10 3 to 10 5 mL -1 and appeared to decrease with depth and with increased salinity of the water. However, in the natural environment of deep (100-500 m) crystalline rocks, where nutrition is limited, formation of biofilms by sessile bacteria is a successful survival strategy. Natural biofilms at the URL and biofilms grown in bioreactors have been studied. The biofilms can accumulate different elements, depending upon the local environment. Precipitates of iron have been found in all the biofilms studied, where they are either passively accumulated or utilized as an energy source. Within the biofilm active and extensive biogeochemical immobilization of dissolved elements is controlled by distinct bacterial activities which are sufficiently discrete for hematite and siderite to be precipitated in close proximity

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

    DEFF Research Database (Denmark)

    Haugaard, Rasmus; Frei, Robert; Stendal, Henrik

    2013-01-01

    unconformably on a basement of tonalite–trondhjemite–granodiorite (TTG) lithologies. Felsic metagreywackes, meta-semipelites and thinly bedded ferruginous shales were identified intercalated with the Itilliarsuk BIF. Other associated rocks include metapelites, acidic metavolcanics and metagabbroic sills.......29. The associated supracrustal rocks in the study area have significantly higher, positive ɛNd(i) values. The 143Nd/144Nd in the Itilliarsuk BIF, therefore, contrasts world BIFs by exhibiting radiogenic, positive ɛNd(i) values in shallow seawaters where the REY's were controlled by a local, depleted continental...... crust, whereas the negative ɛNd(i) values found in the iron-rich layers suggest that the submarine hydrothermal source was influenced by an enriched mantle, possibly an older subcontinental lithospheric segment. The felsic metagreywackes are immature, first-cycle (SiO2/Al2O3 ∼ 4.4, [La/Yb >> 1]CHON...

  11. Intellektuaalne rock

    Index Scriptorium Estoniae

    2007-01-01

    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

  12. Average contents of uranium and thorium in the most important types of rocks of the Ukrainian shield

    International Nuclear Information System (INIS)

    Belevtsev, Ya.N.; Egorov, Yu.P.; Titov, V.K.; Sukhinin, A.M.; Grechishnikova, Z. M.; Zayats, V.B.; Tikhonenko, V.A.; Zhukova, A.M.

    1975-01-01

    The data given concern uranium and thorium contents in the most important rock types of the Ukraina shield. The smallest quantities of uranium are characteristic for the vulcanic rocks of basic and ultrabasic rocks. Archean formations, whose source materials were mainly basic and ultrabasic vulcanites, are marked by this low uranium content. The highest uranium content is observed in the clastogenic rocks of low Proterozoic. The average uranium content is observed in silty argellite rocks represented by crystal slates and paragneissis. Rheomorphic and metasomatic granites and granosyenites of low and middle Proterozoic are also characterized by an increased content of uranium. The platform precipitation rocks of high Proterozoic possess a relatively low uranium content. Thorium concentrations with low thorium-uranium proportions in granites, syenites and granosyenites prove their enrichment in uranium

  13. Igneous Rocks

    Science.gov (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.

  14. Review of potential host rocks for radioactive waste disposal in the Piedmont Province of Georgia

    International Nuclear Information System (INIS)

    Wenner, D.B.; Gillon, K.A.

    1980-10-01

    A literature study was conducted on the Piedmont province of Georgia to designate areas that may be favorable for field exploration for consideration of a repository for storage of radioactive waste. The criteria utilized in such a designation was based upon consideration of the rock unit having favorable geological, geotechnical, and geohydrological features. The most important are that the rock unit have: (1) satisfactory unit dimensions (> 100 km 2 outcrop area and at least 1500 meters (approx. 5000 feet) depth of a continuous rock type); and (2) acceptable geohydrological conditions. Among all rock types, it is concluded that the granites of the large post-metamorphic plutons and large, homogeneous orthogneissic units offer the most favorable geologic settings for exploration for siting a radioactive waste repository. Virtually all other rock types, including most metavolcanic and metasedimentary lithologies have unacceptable unit dimensions, generally unfavorable geohydrologic settings, and deleterious mechanical and physical geotechnical properties. After consideration of all major lithologies that comprise the Georgia Piedmont, the following units were deemed favorable: (1) the Elberton Pluton; (2) the Siloam Pluton; (3) the Sparta Pluton; (4) two unnamed plutons adjacent to the Snelson body of S.W. Georgia; (5) the Lithonia Gneiss; (6) basement orthogneisses and charnockites of the Pine Mountain Belt

  15. Exploring the techno-economic feasibility of mine rock waste utilisation in road works: The case of a mining deposit in Ghana.

    Science.gov (United States)

    Agyeman, Stephen; Ampadu, Samuel I K

    2016-02-01

    Mine rock waste, which is the rock material removed in order to access and mine ore, is free from gold processing chemical contaminants but presents a significant environmental challenge owing to the large volumes involved. One way of mitigating the environmental and safety challenges posed by the large volume of mine rock waste stockpiled in mining communities is to find uses of this material as a substitute for rock aggregates in construction. This article reports on a study conducted to evaluate the engineering properties of such a mine deposit to determine its suitability for use as road pavement material. Samples of mine rock waste, derived from the granitic and granodioritic intrusive units overlying the gold-bearing metavolcanic rock and volcano-clastic sediments of a gold mining area in Ghana, were obtained from three mine rock waste disposal facilities and subjected to a battery of laboratory tests to determine their physical, mechanical, geotechnical, geometrical and durability properties. The overall conclusion was that the mine rock waste met all the requirements of the Ghana Ministry of Transportation specification for use as aggregates for crushed rock subbase, base and surface dressing chippings for road pavements. The recommendation is to process it into the required sizes for the various applications. © The Author(s) 2015.

  16. White Rock

    Science.gov (United States)

    2002-01-01

    (Released 19 April 2002) The Science 'White Rock' is the unofficial name for this unusual landform which was first observed during the Mariner 9 mission in the early 1970's. As later analysis of additional data sets would show, White Rock is neither white nor dense rock. Its apparent brightness arises from the fact that the material surrounding it is so dark. Images from the Mars Global Surveyor MOC camera revealed dark sand dunes surrounding White Rock and on the floor of the troughs within it. Some of these dunes are just apparent in the THEMIS image. Although there was speculation that the material composing White Rock could be salts from an ancient dry lakebed, spectral data from the MGS TES instrument did not support this claim. Instead, the White Rock deposit may be the erosional remnant of a previously more continuous occurrence of air fall sediments, either volcanic ash or windblown dust. The THEMIS image offers new evidence for the idea that the original deposit covered a larger area. Approximately 10 kilometers to the southeast of the main deposit are some tiny knobs of similarly bright material preserved on the floor of a small crater. Given that the eolian erosion of the main White Rock deposit has produced isolated knobs at its edges, it is reasonable to suspect that the more distant outliers are the remnants of a once continuous deposit that stretched at least to this location. The fact that so little remains of the larger deposit suggests that the material is very easily eroded and simply blows away. The Story Fingers of hard, white rock seem to jut out like icy daggers across a moody Martian surface, but appearances can be deceiving. These bright, jagged features are neither white, nor icy, nor even hard and rocky! So what are they, and why are they so different from the surrounding terrain? Scientists know that you can't always trust what your eyes see alone. You have to use other kinds of science instruments to measure things that our eyes can

  17. Late Archean mineralised cyanobacterial mats and their modern analogs

    Science.gov (United States)

    Kazmierczak, J.; Altermann, W.; Kremer, B.; Kempe, S.; Eriksson, P. G.

    2008-09-01

    Abstract Reported are findings of Neoarchean benthic colonial coccoid cyanobacteria preserved as abundant remnants of mineralized capsules and sheaths visible in SEM images as characteristic patterns after etching highly polished carbonate rock platelets. The samples described herein were collected from the Nauga Formation at Prieska (Kaapvaal craton, South Africa). The stratigraphic position of the sampling horizon (Fig. 1) is bracketed by single zircon ages from intercalated tuffs, of 2588±6 Ma and 2549±7Ma [1]. The cyanobacteria-bearing samples are located within sedimentary sequence which begins with Peritidal Member displaying increasingly transgressive character, passing upward into the Chert Member and followed by the Proto-BIF Member and by the Naute Shale Member of the Nauga Formation successively. All three latter members were deposited below the fair weather wave base. As in our previous report [2], the samples are taken from lenses of massive micritic flat pebble conglomerate occurring in otherwise finely laminated siliceous shales intercalating with thin bedded platy limestone. This part of the Nauga Formation is about 30 m thick. The calcareous, cyanobacteria-bearing flat pebble conglomerate and thin intercalations of fine-grained detrital limestones embedded in the clayey sapropel-rich deposits are interpreted as carbonate sediments winnowed during stormy weather from the nearby located peritidal carbonate platform. The mass occurrence and exceptional preservation of mineralised cyanobacterial remains in the micritic carbonate (Mg-calcite) of the redeposited flat pebbles can be explained by their sudden burial in deeper, probably anoxic clay- and sapropel-rich sediments. When examined with standard petrographic optical microscopic technique, the micritic carbonates show rather obscure structure (Fig. 2a), whereas under the SEM, polished and slightly etched platelets of the same samples reveal surprisingly well preserved patterns (Fig. 2b

  18. Mobility of nutrients and trace metals during weathering in the late Archean

    Science.gov (United States)

    Hao, Jihua; Sverjensky, Dimitri A.; Hazen, Robert M.

    2017-08-01

    The evolution of the geosphere and biosphere depends on the availability of bio-essential nutrients and trace metals. Consequently, the chemical and isotopic variability of trace elements in the sedimentary record have been widely used to infer the existence of early life and fluctuations in the near-surface environment on the early Earth, particularly fluctuations in the redox state of the atmosphere. In this study, we applied late Archean weathering models (Hao et al., 2017), developed to estimate the behavior of major elements and the composition of late Archean world average river water, to explore the behavior of nutrient and trace metals and their potential for riverine transport. We focused on P, Mn, Cr, and Cu during the weathering of olivine basalt. In our standard late Archean weathering model (pCO2,g = 10-1.5 bars, pH2,g = 10-5.0 bars), crustal apatite was totally dissolved by the acidic rainwater during weathering. Our model quantitatively links the pCO2,g of the atmosphere to phosphate levels transported by rivers. The development of late Archean river water (pH = 6.4) resulted in riverine phosphate of at least 1.7 μmolar, much higher than at the present-day. At the end of the early Proterozoic snowball Earth event when pCO2,g could be 0.01-0.10 bars, river water may have transported up to 70 μmolar phosphate, depending on the availability of apatite, thereby stimulating high levels of oxygenic photosynthesis in the marine environment. Crustal levels of Mn in olivine dissolved completely during weathering, except at large extents of weathering where Mn was stored as a component of a secondary carbonate mineral. The corresponding Mn content of river water, about 1.2 μmolar, is higher than in modern river water. Whiffs of 10-5 mole O2 gas or HNO3 kg-1 H2O resulted in the formation of pyrolusite (MnO2) and abundant hematite and simultaneous dramatic decreases in the concentration of Mn(II) in the river water. Chromite dissolution resulted in negligible

  19. Controls on Atmospheric O2: The Anoxic Archean and the Suboxic Proterozoic

    Science.gov (United States)

    Kasting, J. F.

    2015-12-01

    Geochemists have now reached consensus that the Archean atmosphere was mostly anoxic, that a Great Oxidation Event (GOE) occurred at around 2.5 Ga, and that the ensuing Proterozoic atmosphere was consistently oxidized [1,2]. Evidence for this broad-scale change in atmospheric composition comes from a variety of sources, most importantly from multiple sulfur isotopes [3,4]. The details of both the Archean and Proterozoic environments remain controversial, however, as does the underlying cause of the GOE. Evidence of 'whiffs' of oxygen during the Archean [5] now extend back as far as 3.0 Ga, based on Cr isotopes [6]. This suggests that O2 was being produced by cyanobacteria well before the GOE and that the timing of this event may have been determined by secular changes in O2 sinks. Catling et al. [7] emphasized escape of hydrogen to space, coupled with progressive oxidation of the continents and a concomitant decrease in the flux of reduced gases from metamorphism. But hydrogen produced by serpentinization of seafloor could also have been a controlling factor [8]. Higher mantle temperatures during the Archean should have resulted in thicker, more mafic seafloor and higher H2 production; decreasing mantle temperatures during the Proterozoic should have led to seafloor more like that of today and a corresponding decrease in H2 production, perhaps by enough to trigger the GOE. Once the atmosphere became generally oxidizing, it apparently remained that way during the rest of Earth's history. But O2 levels in the mid-Proterozoic could have been as low at 10-3 times the Present Atmospheric Level (PAL) [9]. The evidence, once again, is based on Cr isotopes. Possible mechanisms for maintaining such a 'suboxic' Proterozoic atmosphere will be discussed. Refs: 1. H. D. Holland, Geochim. Cosmochim. Acta 66, 3811 (2002). 2. H. D. Holland, Philosophical Transactions of the Royal Society B-Biological Sciences 361, 903 (Jun 29, 2006). 3. J. Farquhar, H. Bao, M. Thiemans, Science

  20. An Archean Geomagnetic Reversal in the Kaap Valley Pluton, South Africa

    Science.gov (United States)

    Layer; Kroner; McWilliams

    1996-08-16

    The Kaap Valley pluton in South Africa is a tonalite intrusion associated with the Archean Barberton Greenstone Belt. Antipodal paleomagnetic directions determined from the central and marginal parts of the pluton record a geomagnetic reversal that occurred as the pluton cooled. The age of the reversal is constrained by an 40Ar/39Ar plateau age from hornblende at 3214 +/- 4 million years, making it the oldest known reversal. The data presented here suggest that Earth has had a reversing, perhaps dipolar, magnetic field since at least 3.2 billion years ago.

  1. Rock stresses (Grimsel rock laboratory)

    International Nuclear Information System (INIS)

    Pahl, A.; Heusermann, S.; Braeuer, V.; Gloeggler, W.

    1989-01-01

    On the research and development project 'Rock Stress Measurements' the BGR has developed and tested several test devices and methods at GTS for use in boreholes at a depth of 200 m and has carried out rock mechanical and engineering geological investigations for the evaluation and interpretation of the stress measurements. The first time a computer for data processing was installed in the borehole together with the BGR-probe. Laboratory tests on hollow cylinders were made to study the stress-deformation behavior. To validate and to interprete the measurement results some test methods were modelled using the finite-element method. The dilatometer-tests yielded high values of Young's modulus, whereas laboratory tests showed lower values with a distinct deformation anisotropy. Stress measurements with the BGR-probe yielded horizontal stresses being higher than the theoretical overburden pressure and vertical stresses which agree well with the theoretical overburden pressure. These results are comparable to the results of the hydraulic fracturing tests, whereas stresses obtained with CSIR-triaxial cells are generally lower. The detailed geological mapping of the borehole indicated relationships between stress and geology. With regard to borehole depth different zones of rock structure joint frequency, joint orientation, and orientation of microfissures as well as stress magnitude, stress direction, and degree of deformation anisotropy could be distinguished. (orig./HP) [de

  2. CONGLOMERATE ROCKS "BRECCIA VERDE ANTICA" ARCHAEOLOGY, PETROLOGY, DETERIORATION AND TECHNOLOGY OF QUARRYING AT HAMMAMAT QUARRIES IN THE EASTEREN DESERT.

    Directory of Open Access Journals (Sweden)

    dr.HESHAM ABBAS KMALLY

    2010-01-01

    Full Text Available One of the most interesting of the monumental rocks of Egypt is the green conglomerates of the Hammamat valley which was used for bowls, vessels, sarcophagus and other objects, from a very early period. The quarries of wadi Hammamat produced the green ornamental stone known in Roman period as "Breccia verde antica". Generally the ancient conglomerate was used occasionally in Egypt at pharaonic time and late period, but it was quarried chiefly by the Roman for export to Italy. The conglomerate rocks range from coarse to fine conglomerates. They are composed of great assortment of rock fragments such as meta-sediments, meta-volcanic and granites. Some pebbles of the coarse conglomerates are previously deposited conglomerates. Pollution, humidity or moisture, solar radiation, rainfall and groundwater represent important factors for disintegration of green conglomerate rocks. Many types of destruction have been noted such as micro-cracks, fractures, joints, exfoliation, crumbling, discoloration, leaching and staining with iron oxides. The conglomerate rock sometimes changes into fragmented, soft residual and parent matter of the soil. Moreover, individual grains of feldspar and quartz begin to become loosened and the rock shows superficial granular disintegration due to, growth of salts and physiochemical weathering

  3. Geochemistry and geochronology of the Archean and palaeo-Proterozoic formations of southern Cameroon (Ntem group, Congo craton)

    International Nuclear Information System (INIS)

    Rchameni, R.

    1997-01-01

    The aim of this work is to understand the crustal evolution of the NW margin of the Congo craton using structural, petrography, isotopic, geochemical and geochronological studies of the Archean and palaeo-Proterozoic formations of the Ntem group of southern Cameroon. The synthesis of these studies allows to propose a diapir-type gravity model linked with the genesis of granitoids to explain the geodynamical evolution of this part of the craton during the Archean. A convergence model with the collision of the Congo and Sao-Francisco cratons and with crust thickening followed by a relaxation phase is proposed for the palaeo-Proterozoic. (J.S.)

  4. Thermal Inertia of Rocks and Rock Populations

    Science.gov (United States)

    Golombek, M. P.; Jakosky, B. M.; Mellon, M. T.

    2001-01-01

    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.

  5. Evidence for and implications of an Early Archean terrestrial impact record

    International Nuclear Information System (INIS)

    Lowe, D.R.; Byerly, G.R.

    1988-01-01

    Early Archean, 3.5 to 3.2 Ga, greenstone sequences in South Africa and Western Australia contain a well-preserved record of early terrestrial meteorite impacts. The main impact-produced deposits are layers, 10 cm to over 1 m thick, composed largely of sand-sized spherules, 0.1 to 4 mm in diameter. The beds studied to date show an assemblage of features indicating formation by the fall of debris from impact-generated ejecta clouds. Some presented data effectively rule out normal magmatic or sedimentary processes in the origin of these units and provide substantial support for an origin by large impacts on the early earth. The presence of at least four, remarkably thick, nearly pure spherule layers suggests that smaller-scale impact deposits may be even more abundant in these sequences. The existence of a well-preserved Archean terrestrial impact record suggests that a direct source of evidence is available regarding a number of important aspects of early earth history

  6. Evolution of the Archean continental crust in the nucleus of the Yangtze block: Evidence from geochemistry of 3.0 Ga TTG gneisses in the Kongling high-grade metamorphic terrane, South China

    Science.gov (United States)

    Qiu, Xiao-Fei; Ling, Wen-Li; Liu, Xiao-Ming; Lu, Shan-Song; Jiang, Tuo; Wei, Yun-Xu; Peng, Lian-Hong; Tan, Juan-Juan

    2018-04-01

    Archean Tonalite-Trondhjemite-Granodiorite (TTG) rocks are scattered within the Kongling high-grade metamorphic terrane (KHMT) in the northern South China block. A comprehensive geochronological and geochemical study is carried out on the Taoyuan granitic gneisses, a newly recognized TTG suite in the northwestern KHMT. This suite has long been regarded as a Mesoproterozoic magmatic pluton, but U-Pb zircon ages of 2994 ± 22 Ma and 2970 ± 15 Ma are obtained by LA-ICP-MS method in this study. The Taoyuan gneiss suite is trondhjemitic in composition, and has high SiO2 (67.80-74.93 wt.%), Na2O (5.11-5.81 wt.%) contents with Na2O/K2O ratios greater than unity, and low Ni (2.56-7.61 ppm), Cr (1.26-7.67 ppm), Yb (0.32-0.82 ppm) and Y (4.48-11.5 ppm) contents. Plots show large variation in La/Yb and Sr/Y ratios and pronounced depletion in Nb, Ta and Ti in the primitive mantle-normalized spiderdiagram. The gneiss suite also displays two-stage Nd model ages close to its crystallization age with corresponding εNd(t) values of -2.5 to +3.5. It is thus suggested that the Taoyuan gneisses, in fact, is part of the Archean Kongling basement complex. Geochemical evidence implies that the TTG rocks may be derived from partial melting of subducted oceanic crust from a garnetiferous amphibolite source with residual assemblage of garnet + amphibole + plagioclase. Our study further indicates that the nucleus of the Yangtze block might experience a juvenile continental crustal growth during Mesoarchean. We also suggest that the Yangtze block may have its own crustal evolutionary history independent from the North China craton and the Tarim block before Paleoproterozoic.

  7. Reactivation of the Archean-Proterozoic suture along the southern margin of Laurentia during the Mazatzal orogeny: Petrogenesis and tectonic implications of ca. 1.63 Ga granite in southeastern Wyoming

    Science.gov (United States)

    Jones, Daniel S.; Barnes, Calvin G.; Premo, Wayne R.; Snoke, Arthur W.

    2013-01-01

    The presence of ca. 1.63 Ga monzogranite (the “white quartz monzonite”) in the southern Sierra Madre, southeastern Wyoming, is anomalous given its distance from the nearest documented plutons of similar age (central Colorado) and the nearest contemporaneous tectonic margin (New Mexico). It is located immediately south of the Cheyenne belt—a ca. 1.75 Ga Archean-Proterozoic tectonic suture. New geochronological, isotopic, and geochemical data suggest that emplacement of the white quartz monzonite occurred between ca. 1645 and 1628 Ma (main pulse ca. 1628 Ma) and that the white quartz monzonite originated primarily by partial melting of the Big Creek Gneiss, a modified arc complex. There is no evidence that mafic magmas were involved. Open folds of the ca. 1750 Ma regional foliation are cut by undeformed white quartz monzonite. On a regional scale, rocks intruded by the white quartz monzonite have experienced higher pressure and temperature conditions and are migmatitic as compared to the surrounding rocks, suggesting a genetic relationship between the white quartz monzonite and tectonic exhumation. We propose that regional shortening imbricated the Big Creek Gneiss, uplifting the now-exposed high-grade rocks of the Big Creek Gneiss (hanging wall of the thrust and wall rock to the white quartz monzonite) and burying correlative rocks, which partially melted to form the white quartz monzonite. This tectonism is attributed to the ca. 1.65 Ga Mazatzal orogeny, as foreland shortening spread progressively into the Yavapai Province. Mazatzal foreland effects have also been described in the Great Lakes region and have been inferred in the Black Hills of South Dakota. We suggest that the crustal-scale rheologic contrast across the Archean-Proterozoic suture, originally developed along the southern margin of Laurentia, and including the Cheyenne belt, facilitated widespread reactivation of that boundary during the Mazatzal orogeny. This finding emphasizes the degree to

  8. Water - rock interaction in different rock environments

    International Nuclear Information System (INIS)

    Lamminen, S.

    1995-01-01

    The study assesses the groundwater geochemistry and geological environment of 44 study sites for radioactive waste disposal. Initially, the study sites were divided by rock type into 5 groups: (1) acid - intermediate rocks, (2) mafic - ultramafic rocks, (3) gabbros, amphibolites and gneisses that contain calc-silicate (skarn) rocks, (4) carbonates and (5) sandstones. Separate assessments are made of acid - intermediate plutonic rocks and of a subgroup that comprises migmatites, granite and mica gneiss. These all belong to the group of acid - intermediate rocks. Within the mafic -ultramafic rock group, a subgroup that comprises mafic - ultramafic plutonic rocks, serpentinites, mafic - ultramafic volcanic rocks and volcanic - sedimentary schists is also evaluated separately. Bedrock groundwaters are classified by their concentration of total dissolved solids as fresh, brackish, saline, strongly saline and brine-class groundwaters. (75 refs., 24 figs., 3 tabs.)

  9. Diversification in the Archean Biosphere: Insight from NanoSIMS of Microstructures in the Farrel Quartzite of Australia

    Science.gov (United States)

    Oehler, D. Z.; Robert, F.; Walter, M. R.; Sugitani, K.; Meibom, A.; Mostefaoui, S.; Gibson, E. K.

    2010-01-01

    The nature of early life on Earth is difficult to assess because potential Early Archean biosignatures are commonly poorly preserved. Interpretations of such materials have been contested, and abiotic or epigenetic derivations have been proposed (summarized in [1]). Yet, an understanding of Archean life is of astrobiological importance, as knowledge of early evolutionary processes on Earth could provide insight to development of life on other planets. A recently-discovered assemblage of organic microstructures in approx.3 Ga charts of the Farrel Quartzite (FQ) of Australia [2-4] includes unusual spindle-like forms and a variety of spheroids. If biogenicity and syngeneity of these forms could be substantiated, the FQ assemblage would provide a new view of Archean life. Our work uses NanoSIMS to further assess the biogenicity and syngeneity of FQ microstructures. In prior NanoSIMS studies [5-6], we gained an understanding of nano-scale elemental distributions in undisputed microfossils from the Neoproterozoic Bitter Springs Formation of Australia. Those results provide a new tool with which to evaluate poorly preserved materials that we might find in Archean sediments and possibly in extraterrestrial materials. We have applied this tool to the FQ forms.

  10. Multiple sulfur isotopes monitor fluid evolution of an Archean orogenic gold deposit

    Science.gov (United States)

    LaFlamme, Crystal; Sugiono, Dennis; Thébaud, Nicolas; Caruso, Stefano; Fiorentini, Marco; Selvaraja, Vikraman; Jeon, Heejin; Voute, François; Martin, Laure

    2018-02-01

    The evolution of a gold-bearing hydrothermal fluid from its source to the locus of gold deposition is complex as it experiences rapid changes in thermochemical conditions during ascent through the crust. Although it is well established that orogenic gold deposits are generated during time periods of abundant crustal growth and/or reworking, the source of fluid and the thermochemical processes that control gold precipitation remain poorly understood. In situ analyses of multiple sulfur isotopes offer a new window into the relationship between source reservoirs of Au-bearing fluids and the thermochemical processes that occur along their pathway to the final site of mineralisation. Whereas δ34S is able to track changes in the evolution of the thermodynamic conditions of ore-forming fluids, Δ33S is virtually indelible and can uniquely fingerprint an Archean sedimentary reservoir that has undergone mass independent fractionation of sulfur (MIF-S). We combine these two tracers (δ34S and Δ33S) to characterise a gold-bearing laminated quartz breccia ore zone and its sulfide-bearing alteration halo in the (+6 Moz Au) structurally-controlled Archean Waroonga deposit located in the Eastern Goldfields Superterrane of the Yilgarn Craton, Western Australia. Over 250 analyses of gold-associated sulfides yield a δ34S shift from what is interpreted as an early pre-mineralisation phase, with chalcopyrite-pyrrhotite (δ34S = +0.7‰ to +2.9‰) and arsenopyrite cores (δ34S = ∼-0.5‰), to a syn-mineralisation stage, reflected in Au-bearing arsenopyrite rims (δ34S = -7.6‰ to +1.5‰). This shift coincides with an unchanging Δ33S value (Δ33S = +0.3‰), both temporally throughout the Au-hosting hydrothermal sulfide paragenesis and spatially across the Au ore zone. These results indicate that sulfur is at least partially recycled from MIF-S-bearing Archean sediments. Further, the invariant nature of the observed MIF-S signature demonstrates that sulfur is derived from a

  11. Transfer of Metasupracrustal Rocks to Midcrustal Depths in the North Cascades Continental Magmatic Arc, Skagit Gneiss Complex, Washington

    Science.gov (United States)

    Sauer, K. B.; Gordon, S. M.; Miller, R. B.; Vervoort, J. D.; Fisher, C. M.

    2017-12-01

    The metasupracrustal units within the north central Chelan block of the North Cascades Range, Washington, are investigated to determine mechanisms and timescales of supracrustal rock incorporation into the deep crust of continental magmatic arcs. Zircon U-Pb and Hf-isotope analyses were used to characterize the protoliths of metasedimentary and metaigneous rocks from the Skagit Gneiss Complex, metasupracrustal rocks from the Cascade River Schist, and metavolcanic rocks from the Napeequa Schist. Skagit Gneiss Complex metasedimentary rocks have (1) a wide range of zircon U-Pb dates from Proterozoic to latest Cretaceous and (2) a more limited range of dates, from Late Triassic to latest Cretaceous, and a lack of Proterozoic dates. Two samples from the Cascade River Schist are characterized by Late Cretaceous protoliths. Amphibolites from the Napeequa Schist have Late Triassic protoliths. Similarities between the Skagit Gneiss metasediments and accretionary wedge and forearc sediments in northwestern Washington and Southern California indicate that the protolith for these units was likely deposited in a forearc basin and/or accretionary wedge in the Early to Late Cretaceous (circa 134-79 Ma). Sediment was likely underthrust into the active arc by circa 74-65 Ma, as soon as 7 Ma after deposition, and intruded by voluminous magmas. The incorporation of metasupracrustal units aligns with the timing of major arc magmatism in the North Cascades (circa 79-60 Ma) and may indicate a link between the burial of sediments and pluton emplacement.

  12. CERN Rocks

    CERN Multimedia

    2004-01-01

    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.

  13. Evidence for crustal recycling during the Archean: the parental magmas of the stillwater complex

    International Nuclear Information System (INIS)

    McCallum, I.S.

    1988-01-01

    The petrology and geochemistry of the Stillwater Complex, an Archean (2.7 Ga) layered mafic intrusion in the Beartooth Mountains of Montana, is discussed. Efforts to reconstruct the compositions of possible parental magmas and thereby place some constraints on the composition and history of their mantle source regions was studied. A high-Mg andesite or boninite magma best matches the crystallization sequences and mineral compositions of Stillwater cumulates, and represents either a primary magma composition or a secondary magma formed, for example, by assimilation of crustal material by a very Mg-rich melt such as komatiite. Isotopic data do not support the extensive amounts of assimilation required by the komatiite parent hypothesis, and it is argued that the Stillwater magma was generated from a mantle source that had been enriched by recycling and homogenization of older crustal material over a large area

  14. The emerald deposits of ultramafic rocks of Capoeirana and Belmont, State of Minas Gerais, Brazil

    International Nuclear Information System (INIS)

    Abreu Machado, G.; Schorscher, H.

    1998-01-01

    The emerald deposits of Capoeirana and Belmont, State of Minas Gerais (MG), Brazil, occur vithin an area comprising a deeply weathered Archean Metavulcano-Sedimentary Sequence (SVS) in tectonic contact with the Borrachudos Metagranitoids (GB) and Fluorite bearing Foliated Metagranitoids (MGF). The SVS is formed by intercalation s of ultramafic schists and amphibolites, basic to intermediate amphibolites, vulcanoclastic, metapelitic and calcsilicate schists and gneisses, banded iron formation and metacherts. The metaultramafic rocks include minor chromitite cumulates and occur at the base of the SVS. When metasomatized in the shear zones adjoining GB and MGF they host emerald mineralizations. (author)

  15. Extreme Hf and light Fe isotopes in Archean komatiites - a remnant of very early mantle depletion?

    Science.gov (United States)

    Nebel, O.; Sossi, P.; Campbell, I. H.; Van Kranendonk, M. J.

    2014-12-01

    Hafnium isotope signatures in some Archean komatiites (ca. 3.5-3.0 billion years old) require a mantle source with a time-integrated Lu/Hf that exceeds average modern depleted mantle. Investigation of the timing and locus of parent-daughter fractionation in their mantle sources potentially constrains differentiation processes in the early Earth and their subsequent distribution and storage. In addition, they may help to constrain the Hf isotope evolution of the greater depleted mantle. In order to shed light on these processes, we discuss radiogenic Hf isotopes in conjunction with stable Fe isotope systematics in Archean komatiites from the Pilbara craton in Western Australia. Our findings indicate that, after careful evaluation of the effects of alteration, pristine samples are characterised by initial 176Hf/177Hf, which lie above the age-corrected depleted mantle, as a consequence of ancient melt extraction. Iron isotope systematics for these samples further point to a mantle source that is isotopically lighter than average modern depleted mantle, which is also consistent with melt-depletion. Taken together, these observations require a component of an old, super-depleted reservoir in the komatiite mantle source(s) that survived in the mantle for possibly hundreds of millions of years. The Lu/Hf of this refractory mantle appears to be complementary to, and therefore contemporaneous with, the first terrestrial crust, as preserved in Hadean (i.e., > 4 Ga) detrital zircon cores, which may indicate a causal relationship between them. We will discuss implications for very early mantle dynamics and the formation of very early mantle reservoirs.

  16. Empirical Records of Environmental Change across the Archean-Proterozoic Transition

    Science.gov (United States)

    Kaufman, A. J.

    2011-12-01

    Time-series geochemical analyses of scientific drill cores intersecting the Archean-Proterozoic transition suggest a coupling of environmental and biological change that culminated in the pervasive oxygenation of Earth's atmosphere and oceans. Elemental and multiple isotope measurements of sedimentary archives, including carbonate, shale, and banded iron-formation from Western Australia, South Africa, Brazil, and southern Canada, indicate important changes in the carbon, sulfur, and nitrogen cycles that monitor the redox state of the oceans and the cyanobacterial buildup of atmospheric oxygen and ozone. In response, continental weathering would have increased, resulting in the enhanced delivery of sulfate and nutrients to seawater, further stimulating photoautotrophic fluxes of oxygen to surface environments. The positive feedback may additionally be responsible for the decline of atmospheric methane and surface refrigeration, represented by a series of discrete ice ages beginning around 2.4 billion years ago, due to the loss of greenhouse capacity during a time of lower solar luminosity. While speculative, the linkage of surface oxidation with enhanced nutrient supply and development of stratospheric sunscreen soon after the Archean-Proterozoic boundary suggests that the earliest perturbation in the carbon cycle may be associated with the rapid expansion of single-celled eukaryotes. Both sterol synthesis in eukaryotes and aerobic respiration require significant levels of oxygen in the ambient environment. Hence, Earth's earliest ice age(s) and onset of a modern and far more energetic carbon cycle may have been directly related to the global expansion of cyanobacteria that released oxygen to the environment, and of eukaryotes that respired it.

  17. Characterizing the Purple Earth: Modeling the globally integrated spectral variability of the Archean Earth

    International Nuclear Information System (INIS)

    Sanromá, E.; Pallé, E.; López, R.; Montañés-Rodríguez, P.; Parenteau, M. N.; Kiang, N. Y.; Gutiérrez-Navarro, A. M.

    2014-01-01

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. However, the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more widespread life forms on the planet was purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  18. Stratigraphy and uranium potential of early proterozoic metasedimentary rocks in the Medicine Bow Mountains, Wyoming

    International Nuclear Information System (INIS)

    Karlstrom, K.E.; Houston, R.S.

    1979-01-01

    The Medicine Bow Mountains of southeastern Wyoming contain an eight mile (13 km) thick section of Early Proterozoic (2500 to 1700 My b.p.) metasedimentary rocks which is subdivided into three successions: the Phantom Lake Metamorphic Suite (oldest), Deep Lake Group, and Libby Creek Group. The most promising units are the basal conglomerate of the upper Phantom Lake Suite, which appears to unconformably overlie metavolcanics of the lower Phantom Lake Suite, and the Magnolia Formation, which unconformably overlies the upper Phantom Lake Suite. Outcrops of the former have yielded assays of up to 141 ppM U and 916 ppM Th, with no appreciable gold. Outcrops of the Magnolia Formation have yielded up to 8.4 ppM U and 38 ppM Th. Several factors indicate that these units deserve further study. First, the lithologies of the radioactive and nonradioactive units are remarkably similar to those found in known uranium fossil-placers. Second, the paleogeography was favorable for placer accumulation if the conglomerates are fluvial sediments in an epicontinental clastic succession which was deposited during several transgressive-regressive cycles, as interpreted to be, Third, the age of the conglomerates may be similar to the age of other known uranium placers-i.e., more than 2000 My b.p. And fourth, geological and geochemical studies indicate that both uranium and pyrite have been strongly leached from outcrops and that subsurface rocks contain more uranium than surface rocks do

  19. Archean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics?

    Science.gov (United States)

    Kerrich, Robert; Polat, Ali

    2006-03-01

    Mantle convection and plate tectonics are one system, because oceanic plates are cold upper thermal boundary layers of the convection cells. As a corollary, Phanerozoic-style of plate tectonics or more likely a different version of it (i.e. a larger number of slowly moving plates, or similar number of faster plates) is expected to have operated in the hotter, vigorously convecting early Earth. Despite the recent advances in understanding the origin of Archean greenstone-granitoid terranes, the question regarding the operation of plate tectonics in the early Earth remains still controversial. Numerical model outputs for the Archean Earth range from predominantly shallow to flat subduction between 4.0 and 2.5 Ga and well-established steep subduction since 2.5 Ga [Abbott, D., Drury, R., Smith, W.H.F., 1994. Flat to steep transition in subduction style. Geology 22, 937-940], to no plate tectonics but rather foundering of 1000 km sectors of basaltic crust, then "resurfaced" by upper asthenospheric mantle basaltic melts that generate the observed duality of basalts and tonalities [van Thienen, P., van den Berg, A.P., Vlaar, N.J., 2004a. Production and recycling of oceanic crust in the early earth. Tectonophysics 386, 41-65; van Thienen, P., Van den Berg, A.P., Vlaar, N.J., 2004b. On the formation of continental silicic melts in thermochemical mantle convection models: implications for early Earth. Tectonophysics 394, 111-124]. These model outputs can be tested against the geological record. Greenstone belt volcanics are composites of komatiite-basalt plateau sequences erupted from deep mantle plumes and bimodal basalt-dacite sequences having the geochemical signatures of convergent margins; i.e. horizontally imbricated plateau and island arc crust. Greenstone belts from 3.8 to 2.5 Ga include volcanic types reported from Cenozoic convergent margins including: boninites; arc picrites; and the association of adakites-Mg andesites- and Nb-enriched basalts. Archean cratons

  20. On the age of the Onverwacht Group, Swaziland sequence, South Africa. [radioactive dating of stratified igneous rocks

    Science.gov (United States)

    Jahn, B.-M.; Shih, C.-Y.

    1974-01-01

    Some rocks of the Onverwacht Group, South Africa, have been analyzed for Rb and Sr concentrations and Sr isotopic composition. These rocks include volcanic rocks, layered ultramafic differentiates and cherty sediments. Whole rock data indicate that the Rb-Sr isotopic systems in many samples were open and yield no reasonable isochron relationships. However, the data of mineral separates from a basaltic komatiite define a good isochron of 3.50 (plus or minus .2) b.y. with an initial Sr-87/Sr-86 ratio of 0.70048 plus or minus 5. The orthodox interpretation of this age is the time of the low grade metamorphism. It is reasonable to assume that the age of 3.50 b.y. might also represent the time of initial Onverwacht volcanism and deposition. The initial Sr-87/Sr-86 ratio obtained above is important to an understanding of the Sr isotopic composition of the Archean upper mantle.

  1. Rollerjaw Rock Crusher

    Science.gov (United States)

    Peters, Gregory; Brown, Kyle; Fuerstenau, Stephen

    2009-01-01

    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.

  2. U/Pb (SHRIMP), {sup 207}Pb/{sup 206}Pb, Rb/Sr, Sm/Nd e K/Ar geochronology of granite-greenstone terrains of Gaviao Block: implications for the Proterozoic and Archean evolution of Sao Francisco Craton, Brazil; Geocronologia U/Pb (SHRIMP), {sup 207}Pb/{sup 206}Pb, Rb/Sr, Sm/Nd e K/Ar dos terrenos granito-greenstone do Bloco do Gaviao: implicacoes para a evolucao arqueana e proterozoica do craton do Sao Francisco, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Luiz Rogerio Bastos

    1998-07-01

    The Gaviao Block (GB) in the northern portion of the Sao Francisco Craton-Northeast of Brazil, constitutes one of the oldest Archean fragments of the South American Platform Archean crust. GB underwent several events of juvenile accretion and reworking of continental crust along its evolutionary history, notably between the Archean and the Paleoproterozoic. {sup 207}Pb/{sup 206}Pb isotopic analyses were carried out in two zircons populations from strongly migmatized TTG terranes found in the proximity of Brumado: the first population (7 crystals) is taken as representative of the crystallization period of the TTG terranes at 3300 {+-} 45 Ma; the second (2 crystals) represents the age of the first even of metamorphism/migmatization at 2910 {+-} 10 Ma. {sup 207} Pb/{sup 206} Pb analyses in zircons from an outcrop of non-migmatized TTG in the area yielded a 3202 {+-} 15 Ma age (4 crystals), interpreted to be the crystallization period of the gneiss protolith. Sm/Nd analyses on the TTG rocks of the Brumado region yielded T{sub DM} model ages varying between 3.26 and 3.36 Ga and {epsilon}{sub Nd}{sup (t)} between -3.5 and +0.7. These data suggest the occurrence of juvenile accretions to the continental crust during the Archean, with differential involvement of crustal materials. The geochemical data of rare earth elements corresponding to the TTG terranes revealed moderate LRRE contents (La{sub N}=83,5), low HREE contents (La{sub N}=2,5) and a fairly fractionated pattern (La/Yb){sub N}=34, besides lack of negative Eu anomaly, showing that these rocks have similar compositions to those TTG terranes of cratonic continents, as well as some Archean rocks from CSF (e.g. Sete Voltas, Boa Vista). Finally, the youngest ages present in GB rocks (ca. 1.2-0.45 Ga) represent the role played by tectono thermal events, which produced partial or total rejuvenation of the Rb/Sr and K/Ar isotopic systems during the Espinhaco and Brasiliano cycles. In particular, K/Ar ages illustrate the

  3. Review of potential host rocks for radioactive waste disposal in the southeast United States-Southern Piedmont subregion

    International Nuclear Information System (INIS)

    1980-10-01

    A literature study was conducted on the geology of the Southern Piedmont province in the states of Maryland, Virginia, North Carolina, South Carolina, and Georgia. The purpose was to identify geologic areas potentially suitable for containment of a repository for the long-term isolation of solidified radioactive waste. The crystalline rocks of the Southern Piedmont province range in age from Precambrian to Paleozoic, and are predominantly slates, phyllites, argillites, schists, metavolcanics, gneisses, gabbros, and granites. These rock units were classified as either favorable, potentially favorable, or unfavorable as potential study areas based on an evaluation of the geologic, hydrologic, and geotechnical characteristics. No socio-economic factors were considered. Rocks subjected to multiple periods of deformation and metamorphism, or described as highly fractured, or of limited areal extent were generally ranked as unfavorable. Potentially favorable rocks are primarily the high-grade metamorphic gneisses and granites. Sixteen areas were classified as being favorable for additional study. These areas are primarily large igneous granite plutons as follows: the Petersburg granite in Virginia; the Rolesville-Castallia, Churchland, and Landis plutons in North Carolina; the Liberty Hill, Winnsboro, and Ogden plutons in South Carolina; and the Siloam, Elberton, and six unnamed granite plutons in Georgia

  4. Sulfur Isotope Trends in Archean Microbialite Facies Record Early Oxygen Production and Consumption

    Science.gov (United States)

    Zerkle, A.; Meyer, N.; Izon, G.; Poulton, S.; Farquhar, J.; Claire, M.

    2014-12-01

    The major and minor sulfur isotope composition (δ34S and Δ33S) of pyrites preserved in ~2.65-2.5 billion-year-old (Ga) microbialites record localized oxygen production and consumption near the mat surface. These trends are preserved in two separate drill cores (GKF01 and BH1-Sacha) transecting the Campbellrand-Malmani carbonate platform (Ghaap Group, Transvaal Supergroup, South Africa; Zerkle et al., 2012; Izon et al., in review). Microbialite pyrites possess positive Δ33S values, plotting parallel to typical Archean trends (with a Δ33S/δ34S slope of ~0.9) but enriched in 34S by ~3 to 7‰. We propose that these 34S-enriched pyrites were formed from a residual pool of sulfide that was partially oxidized via molecular oxygen produced by surface mat-dwelling cyanobacteria. Sulfide, carrying the range of Archean Δ33S values, could have been produced deeper within the microbial mat by the reduction of sulfate and elemental sulfur, then fractionated upon reaction with O2 produced by oxygenic photosynthesis. Preservation of this positive 34S offset requires that: 1) sulfide was only partially (50­­-80%) consumed by oxidation, meaning H2S was locally more abundant (or more rapidly produced) than O2, and 2) the majority of the sulfate produced via oxidation was not immediately reduced to sulfide, implying either that the sulfate pool was much larger than the sulfide pool, or that the sulfate formed near the mat surface was transported and reduced in another part of the system. Contrastingly, older microbialite facies (> 2.7 Ga; Thomazo et al., 2013) appear to lack these observed 34S enrichments. Consequently, the onset of 34S enrichments could mark a shift in mat ecology, from communities dominated by anoxygenic photosynthesizers to cyanobacteria. Here, we test these hypotheses with new spatially resolved mm-scale trends in sulfur isotope measurements from pyritized stromatolites of the Vryburg Formation, sampled in the lower part of the BH1-Sacha core. Millimeter

  5. The oxygen isotope composition of earth's oldest rocks and evidence of a terrestrial magma ocean

    DEFF Research Database (Denmark)

    Rumble, D.; Bowring, S.; Iizuka, T.

    2013-01-01

    Analysis of Hadean and Archean rocks for O-16-O-17-O-18 isotopes demonstrates that the Terrestrial Mass Fractionation Line of oxygen isotopes has had the same slope and intercept for at least the past 4.0 and probably for as long as 4.2Ga. The homogenization of oxygen isotopes required to produce....... But other sources of heat for global melting cannot be excluded such as bolide impacts during early accretion of proto-Earth, the decay of short-lived radioactive isotopes, or the energy released during segregation of core from mantle.......Analysis of Hadean and Archean rocks for O-16-O-17-O-18 isotopes demonstrates that the Terrestrial Mass Fractionation Line of oxygen isotopes has had the same slope and intercept for at least the past 4.0 and probably for as long as 4.2Ga. The homogenization of oxygen isotopes required to produce...... such long-lived consistency was most easily established by mixing in a terrestrial magma ocean. The measured identical oxygen isotope mass fractionation lines for Earth and Moon suggest that oxygen isotope reservoirs of both bodies were homogenized at the same time during a giant moon-forming impact...

  6. Archean Earth Atmosphere Fractal Haze Aggregates: Light Scattering Calculations and the Faint Young Sun Paradox

    Science.gov (United States)

    Boness, D. A.; Terrell-Martinez, B.

    2010-12-01

    As part of an ongoing undergraduate research project of light scattering calculations involving fractal carbonaceous soot aggregates relevant to current anthropogenic and natural sources in Earth's atmosphere, we have read with interest a recent paper [E.T. Wolf and O.B Toon,Science 328, 1266 (2010)] claiming that the Faint Young Sun paradox discussed four decades ago by Carl Sagan and others can be resolved without invoking heavy CO2 concentrations as a greenhouse gas warming the early Earth enough to sustain liquid water and hence allow the origin of life. Wolf and Toon report that a Titan-like Archean Earth haze, with a fractal haze aggregate nature due to nitrogen-methane photochemistry at high altitudes, should block enough UV light to protect the warming greenhouse gas NH3 while allowing enough visible light to reach the surface of the Earth. To test this hypothesis, we have employed a rigorous T-Matrix arbitrary-particle light scattering technique, to avoid the simplifications inherent in Mie-sphere scattering, on haze fractal aggregates at UV and visible wavelenths of incident light. We generate these model aggregates using diffusion-limited cluster aggregation (DLCA) algorithms, which much more closely fit actual haze fractal aggregates than do diffusion-limited aggregation (DLA) algorithms.

  7. Gas bubble dimensions in Archean lava flows indicate low air pressure at 2.7 Ga

    Science.gov (United States)

    Som, S. M.; Buick, R.; Hagadorn, J.; Blake, T.; Perreault, J.; Harnmeijer, J.; Catling, D. C.

    2014-12-01

    Air pressure constrains atmospheric composition, which, in turn, is linked to the Earth system through biogeochemical cycles and fluxes of volatiles from and to the Earth's interior. Previous studies have only placed maximum levels on surface air pressure for the early Earth [1]. Here, we calculate an absolute value for Archean barometric pressure using gas bubble size (vesicle) distributions in uninflated basaltic lava flows that solidified at sea level 2.7 billion years ago in the Pilbara Craton, Western Australia. These vesicles have been filled in by secondary minerals deposited during metasomatism and so are now amydules, but thin sections show that infilling did not change vesicle dimensions. Amygdule dimensions are measured using high-resolution X-ray tomography from core samples obtained from the top and bottom of the lava flows. The modal size expressed at the top and at the bottom of an uninflated flow can be linked to atmospheric pressure using the ideal gas law. Such a technique has been verified as a paleoaltimeter using Hawaiian Quaternary lava flows [2]. We use statistical methods to estimate the mean and standard deviation of the volumetric size of the amygdules by applying 'bootstrap'resampling and the Central Limit Theorem. Our data indicate a surprisingly low atmospheric pressure. Greater nitrogen burial under anaerobic conditions likely explains lower pressure. Refs: [1] Som et al. (2012) Nature 484, 359-262. D. L. Sahagian et al. (2002) J. Geol., 110, 671-685.

  8. Rocks Can Wow? Yes, Rocks Can Wow!

    Science.gov (United States)

    Hardman, Sally; Luke, Sue

    2016-01-01

    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…

  9. Migmatites and migmatite-like rocks of Olkiluoto

    International Nuclear Information System (INIS)

    Kaerki, A.

    2015-02-01

    Bedrock of the Olkiluoto Island in the western end of the Palaeoproterozoic Svecofennian Accretionary Arc Complex, SW Finland is composed of high-grade metamorphic pelites, arenites and intermediate, arc type metavolcanic rocks intruded by granodioritic to tonalitic plutonic rocks. Regional metamorphism culminated with voluminous migmatization in the temperature of 660 - 700 deg C and relatively low pressure of about 3.5 - 4 kbar. The end result of polyphase metamorphism and deformation is a metamorphic rock succession composed of diverse migmatite rocks, metatexites and diatexites. Metatexites are migmatites in which several, discrete components can be detected, and in which the paleosome with some pre-partial-melting textures is identifiable. Diatexites are more advanced migmatites in which the pre-migmatization structures are often totally destroyed and the rock is dominated by different neosome components meaning leucosome, melanosome or mesosome. Based on the migmatite structures the metatexites of Olkiluoto have been classified into six subgroups. Dike-structured metatexites are composed of well preserved paleosome intruded by one single set of narrow, subparallel leucosome dikes which cover ca. 5 - 10 % of the whole rock volume. Net-structure is composed of a network of narrow leucosome dikes which show a reticulated structure in a plane section and cover less than 30 % of the whole rock volume. Breccia-structure is composed of angular or rounded paleosome blocks surrounded by moderate amount of leucosome. Patch-structure is composed of irregular leucosome patches which intruded the well preserved paleosome and compose typically 20 - 70 % of the rock volume. Layer-structure is characterized by more or less regular leucosome dikes sub-parallel to the foliation of the well preserved paleosome. Vein-structured metatexites and also diatexites include a set of pipe-like, longish leucosome veins most probably generated by synchronous melting and deformation

  10. Migmatites and migmatite-like rocks of Olkiluoto

    Energy Technology Data Exchange (ETDEWEB)

    Kaerki, A. [Kivitieto Oy, Oulu (Finland)

    2015-02-15

    Bedrock of the Olkiluoto Island in the western end of the Palaeoproterozoic Svecofennian Accretionary Arc Complex, SW Finland is composed of high-grade metamorphic pelites, arenites and intermediate, arc type metavolcanic rocks intruded by granodioritic to tonalitic plutonic rocks. Regional metamorphism culminated with voluminous migmatization in the temperature of 660 - 700 deg C and relatively low pressure of about 3.5 - 4 kbar. The end result of polyphase metamorphism and deformation is a metamorphic rock succession composed of diverse migmatite rocks, metatexites and diatexites. Metatexites are migmatites in which several, discrete components can be detected, and in which the paleosome with some pre-partial-melting textures is identifiable. Diatexites are more advanced migmatites in which the pre-migmatization structures are often totally destroyed and the rock is dominated by different neosome components meaning leucosome, melanosome or mesosome. Based on the migmatite structures the metatexites of Olkiluoto have been classified into six subgroups. Dike-structured metatexites are composed of well preserved paleosome intruded by one single set of narrow, subparallel leucosome dikes which cover ca. 5 - 10 % of the whole rock volume. Net-structure is composed of a network of narrow leucosome dikes which show a reticulated structure in a plane section and cover less than 30 % of the whole rock volume. Breccia-structure is composed of angular or rounded paleosome blocks surrounded by moderate amount of leucosome. Patch-structure is composed of irregular leucosome patches which intruded the well preserved paleosome and compose typically 20 - 70 % of the rock volume. Layer-structure is characterized by more or less regular leucosome dikes sub-parallel to the foliation of the well preserved paleosome. Vein-structured metatexites and also diatexites include a set of pipe-like, longish leucosome veins most probably generated by synchronous melting and deformation

  11. Ultramafic rocks of the western Idaho suture zone: Asbestos Peak and Misery Ridge

    Energy Technology Data Exchange (ETDEWEB)

    Godchaux, M.M. (Mount Holyoke Coll., South Hadley, MA (United States). Dept. of Geology); Bonnichsen, B. (Univ. of Idaho, Moscow, ID (United States))

    1993-04-01

    The Western Idaho Ultramafic Belt extends northward from the town of Weiser to the northern end of Dworshak Reservoir; in its northern portion most of the ultramafic bodies are localized along the suture zone where the Mesozoic oceanic accreted terranes meet the continental craton. Of the twenty bodies investigated, all are small, all are in fault contact with their metavolcanic and metasedimentary host rocks, all have been metamorphosed, and all display deformational fabrics in at least some portion of the outcrop area, suggesting that deformation continued after peak metamorphism. The degree of metamorphism ranges from incipient serpentinization to attainment of equilibrium in the upper amphibolite facies. Some bodies have been intruded by granitic dikes or pegmatite veins after emplacement, and have locally undergone contact metasomatism. Two particularly complex bodies, Asbestos Peak and Misery Ridge, were chosen for detailed petrographic and chemical study. Asbestos Peak is composed mostly of decussate anthophyllite-talc rock containing isolated patches of harzburgite protolith, and has blackwall border zones. Misery Ridge is composed mostly of coarse-grained sheared tremolite-talc schist without remnant protolith, and lacks true blackwall zones. Both bodies exhibit an unusual and enigmatic hornblende-poikiloblastic garnet-green spinel-skeletal ilmenite assemblage, present in some places as well-defined border zones and in other places as cross-cutting bodies.

  12. U enrichment and Th/U fractionation in Archean boninites: Implications for paleo-ocean oxygenation and U cycling at juvenile subduction zones

    Science.gov (United States)

    Manikyamba, C.; Said, Nuru; Santosh, M.; Saha, Abhishek; Ganguly, Sohini; Subramanyam, K. S. V.

    2018-05-01

    Phanerozoic boninites record enrichments of U over Th, giving Th/U: 0.5-1.6, relative to intraoceanic island arc tholeiites (IAT) where Th/U averages 2.6. Uranium enrichment is attributed to incorporation of shallow, oxidized fluids, U-rich but Th-poor, from the slab into the melt column of boninites which form in near-trench to forearc settings of suprasubduction zone ophiolites. Well preserved Archean komatiite-tholeiite, plume-derived, oceanic volcanic sequences have primary magmatic Th/U ratios of 4.4-3.6, and Archean convergent margin IAT volcanic sequences, having REE and HFSE compositions similar to Phanerozoic IAT equivalents, preserve primary Th/U of 4-3.6. The best preserved Archean boninites of the 3.0 Ga Olondo and 2.7 Ga Gadwal greenstone belts, hosted in convergent margin ophiolite sequences, also show relative enrichments of U over Th, with low average Th/U ∼3 relative to coeval IAT, and Phanerozoic counterparts which are devoid of crustal contamination and therefore erupted in an intraoceanic setting, with minimal contemporaneous submarine hydrothermal alteration. Later enrichment of U is unlikely as Th-U-Nb-LREE patterns are coherent in these boninites whereas secondary effects induce dispersion of Th/U ratios. The variation in Th/U ratios from Archean to Phanerozoic boninites of greenstone belts to ophiolitic sequences reflect on genesis of boninitic lavas at different tectono-thermal regimes. Consequently, if the explanation for U enrichment in Phanerozoic boninites also applies to Archean examples, the implication is that U was soluble in oxygenated Archean marine water up to 600 Ma before the proposed great oxygenation event (GOE) at ∼2.4 Ga. This interpretation is consistent with large Ce anomalies in some hydrothermally altered Archean volcanic sequences aged 3.0-2.7 Ga.

  13. Rock slope design guide.

    Science.gov (United States)

    2011-04-01

    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...

  14. Rock Slope Design Criteria

    Science.gov (United States)

    2010-06-01

    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 ...

  15. The Rock Cycle

    Science.gov (United States)

    Singh, Raman J.; Bushee, Jonathan

    1977-01-01

    Presents a rock cycle diagram suitable for use at the secondary or introductory college levels which separates rocks formed on and below the surface, includes organic materials, and separates products from processes. (SL)

  16. U Pb and Lu Hf isotope record of detrital zircon grains from the Limpopo Belt Evidence for crustal recycling at the Hadean to early-Archean transition

    Science.gov (United States)

    Zeh, Armin; Gerdes, Axel; Klemd, Reiner; Barton, J. M., Jr.

    2008-11-01

    Detrital zircon grains from Beit Bridge Group quartzite from the Central Zone of the Limpopo Belt near Musina yield mostly ages of 3.35-3.15 Ga, minor 3.15-2.51 Ga components, and numerous older grains grouped at approximately 3.4, 3.5 and 3.6 Ga. Two grains yielded concordant Late Hadean U-Pb ages of 3881 ± 11 Ma and 3909 ± 26 Ma, which are the oldest zircon grains so far found in Africa. The combined U-Pb and Lu-Hf datasets and field relationships provide evidence that the sedimentary protolith of the Beit Bridge Group quartzite was deposited after the emplacement of the Sand River Gneisses (3.35-3.15 Ga), but prior to the Neoarchean magmatic-metamorphic events at 2.65-2.60 Ga. The finding of abundant magmatic zircon detritus with concordant U-Pb ages of 3.35-3.15 Ga, and 176Hf/ 177Hf of 0.28066 ± 0.00004 indicate that the Sand River Gneiss-type rocks were a predominant source. In contrast, detrital zircon grains older than approximately 3.35 Ga were derived from the hinterland of the Limpopo Belt; either from a so far unknown crustal source in southern Africa, possibly from the Zimbabwe Craton and/or a source, which was similar but not necessarily identical to the one that supplied the Hadean zircons to Jack Hills, Western Australia. The Beit Bridge Group zircon population at >3.35 Ga shows a general ɛHf t increase with decreasing age from ɛHf 3.9Ga = -6.3 to ɛHf 3.3-3.1Ga = -0.2, indicating that Hadean crust older than 4.0 Ga ( TDM = 4.45-4.36 Ga) was rejuvenated during magmatic events between >3.9 and 3.1 Ga, due to a successive mixing of crustal rocks with mantle derived magmas. The existence of a depleted mantle reservoir in the Limpopo's hinterland is reflected by the ˜3.6 Ga zircon population, which shows ɛHf 3.6Ga between -4.6 and +3.2. In a global context, our data suggest that a long-lived, mafic Hadean protocrust with some tonalite-trondhjemite-granodiorite constituents was destroyed and partly recycled at the Hadean/Archean transition, perhaps

  17. Petrology and geochemistry of the marbles and calcosilicated rocks from Ipira, Bahia - Brazil

    International Nuclear Information System (INIS)

    Oliveira, M.A.F.T. de.

    1976-01-01

    This work explains a study of marbles and diopsitites from Serra das Panelas, Ipira, Bahia, Brazil. Petrographic analysis, chemistry some elements, trace elements and rare earths, isotopic analysis of Strontium, carbon and oxigen, and geochronological determinations were done. The ages founded correspond to Transamazonic Orogenetic cicle, with Archean age, confirmed by the 18 O values found, which give to marble, ages about 2.500 my. The mineralogy and the texture give to marble an invulgar aspect, making a confusion with carbonate. The petrochemical data and the geochemistry of 13 C and 18 O isotopes showed that the marble and diopsitites was formed from the old marine carbonates. The geochemistry of rare earth suggests a strong correlation with carbonitic and alkaline rocks. An hybrid origem to this rocks is proposed. (C.D.G.) [pt

  18. Litho stratigraphy of precambrian rocks in middle Xingu river basin -Altamira, Para state, Brazil

    International Nuclear Information System (INIS)

    Santos, M.V. dos; Sousa Filho, E.E. dos; Tassinari, C.C.G.

    1988-01-01

    The basement rocks from the Xingu river is divided into five litho stratigraphic units. They are broadly characterized by domains of ortho and para gneisses, volcano-sedimentary sequences, migmatites and by syntectonic and latetectonic granitoids. In addition acid to intermediate volcanics (Iriri formation) and several sub-volcanic granitic plutons (Maloquinha suite) also occur within the investigated area, as well as basic intrusions and minor arenous sediments covers, slightly metamorphosed. Geochronological studies carried out on the basement rocks and on the volcanics demonstrates an geologic evolution restricted to the trans Amazonian cycle (2.1 - 1.9 Ga). Sr isotopic evolution (high initial 87 Sr/ 86 Sr ratios) suggest that strong reworking of crustal material occurred at this time, in association with the tectonic evolution of the Maroni-Itacaiunas mobile belt related to the lower proterozoic, which borders the northern and northerneast part of the Archean central Amazonian province. (author)

  19. Review of potential host rocks for radioactive waste disposal in the southeast United States: Southeastern Coastal Plain Subregion

    International Nuclear Information System (INIS)

    1980-10-01

    A literature review was made of the geological characteristics of the Southeastern Coastal Plain physiograhic province in the states of Maryland, Virginia, North Carolina, South Carolina, and Georgia. The purpose of this study was to identify candidate exploration areas for the possible location of a mined repository for the storage of radioactive waste in the argillaceous sedimentary rocks of the Coastal Plain. Candidate areas were selected on the basis of geological characteristics, available subsurface data, and generally accepted requirements for waste isolation developed by previous studies. Factors considered in the evaluation include the stratigraphy and lithology, geologic history, structure, seismicity, hydrogeology, and natural resources of the candidate area. Unlike other potential regions, the Southeastern Coastal Plain is not composed of competent rock, but consists primarily of unconsolidated and water-saturated sediments overlying a basement of crystalline and metavolcanic rocks. Thus, construction of both shafts and tunnels to depths of approx. 1000 meters may encounter difficulties. Socio-economic and construction considerations have not been addressed in the evaluation. Based on the applied criteria, four areas were selected as being most favorable for future field investigation. These include one in Maryland, one in North Carolina, and two in Georgia

  20. Stable isotopic information on calcareous pelitic rocks in the Tizapa volcanogenic massive sulfide deposit area, the United Mexican States

    International Nuclear Information System (INIS)

    Morozumi, Haruhisa; Metsugi, Hideya; Kita, Yoshiyuki; Suzuki, Toru

    1999-01-01

    Tizapa volcanogenic massive sulfide (VMS) deposit is hosted in greenschist facies metamorphic rocks; footwall is green schist of felsic to mafic metavolcanic rocks and hanging wall is graphite schist of metasedimentary pelitic rock. Pb-Pb dating of ore samples indicates 103.4Ma to 156.3Ma for the age of mineralization (JICA/MMAJ, 1991). Hanging wall graphite schist is partially calcareous and overlaid by upper formations consisting of calcareous shake and limestone. δ 13 C(per mille) PDB values were measured for carbonate and organic material in the graphite schist, and δ 18 O(per mille) SMOW values were also measured for same carbonate. Although carbonate and organic material were affected by the metamorphism after mineralization, δ 18 O of carbonate decreases from +22.1 per mille to +17.9 per mille, δ 13 C of carbonate decreases from +0.8 per mille to -4.3 per mille and δ 13 C of organic material decreases from -10.0 per mille to -15.6 per mille with the decrease of vertical distances to ore deposit from 54.20 m to 10.28 m. This phenomenon might indicate the change of sedimentary environment of the reduced condition where the sulfides were precipitated, with the change of temperature. If this assumption is adequate, the method applied in this study is useful for semi-quantitative evaluation to distinguish the favorable condition for the precipitation of sulfides of VMS. (author)

  1. Strain analysis and microstructural evolution characteristic of neoproterozoic rocks associations of Wadi El Falek, centre Eastern Desert, Egypt

    Science.gov (United States)

    Kassem, Osama M. K.; Rahim, Said H. Abd El; Nashar, El Said R. El

    2012-09-01

    The estimation of finite strain in rocks is fundamental to a meaningful understanding of deformational processes and products on all scales from microscopic fabric development to regional structural analyses. The Rf/φ and Fry methods on feldspar porphyroclasts and mafic grains from 5 granite, 1 metavolcanic, 3 metasedimentary and 1 granodiorite samples were used in Wadi El Falek region. Finite-strain data shows that a high to moderate range of deformation of the granitic to metavolcano-sedimentary samples and axial ratios in the XZ section range from 1.60 to 4.10 for the Rf/φ method and from 2.80 to 4.90 for the Fry method. Furthermore, the short axes are subvertical associated with a subhorizontal foliation. We conclude that finite strain in the deformed granite rocks is of the same order of magnitude as that from metavolcano-sedimentary rocks. Furthermore, contacts formed during intrusion of plutons with some faults in the Wadi El Falek area under brittle to semi-ductile deformation conditions. In this case, finite strain accumulated during superimposed deformation on the already assembled nappe structure. It indicates that the nappe contacts formed during the accumulation of finite strain.

  2. Re-Os ages for Archean molybdenite and pyrite, Kuittila-Kivisuo, Finland and Proterozoic molybdenite, Kabeliai, Lithuania: Testing the chronometer in a metamorphic and metasomatic setting

    Science.gov (United States)

    Stein, H.J.; Sundblad, K.; Markey, R.J.; Morgan, J.W.; Motuza, G.

    1998-01-01

    Seven 187Re-187Os ages were determined for molybdenite and pyrite samples from two well-dated Precambrian intrusions in Fennoscandia to examine the sustainability of the Re-Os chronometer in a metamorphic and metasomatic setting. Using a new 187Re decay constant (1.666 x 10-11y-1) with a much improved uncertainty (±0.31%), we determined replicate Re-Os ages for molybdenite and pyrite from the Kuittila and Kivisuo prospects in easternmost Finland and for molybdenite from the Kabeliai prospect in southernmost Lithuania. These two localities contain some of the oldest and youngest plutonic activity in Fennoscandia and are associated with newly discovered economic Au mineralization (Ilomantsi, Finland) and a Cu-Mo prospect (Kabeliai, Lithuania). Two Re-Os ages for veinhosted Kabeliai molybdenite average 1486 ± 5 Ma, in excellent agreement with a 1505 ± 11 Ma U-Pb zircon age for the hosting Kabeliai granite pluton. The slightly younger age suggests the introduction of Cu-Mo mineralization by a later phase of the Kabeliai magmatic system. Mean Re-Os ages of 2778 ± 8 Ma and 2781 ± 8 Ma for Kuittila and Kivisuo molybdenites, respectively, are in reasonable agreement with a 2753 ± 5 Ma weighted mean U-Pb zircon age for hosting Kuittila tonalite. These Re-Os ages agree well with less precise ages of 2789 ± 290 Ma for a Rb-Sr whole-rock isochron and 2771 ± 75 Ma for the average of six Sm-Nd T(DM) model ages for Kuittila tonalite. Three Re-Os analyses of a single pyrite mineral separate, from the same sample of Kuittila pluton that yielded a molybdenite separate, provide individual model ages of 2710 ± 27, 2777 ± 28, and 2830 ± 28 Ma (Re = 17.4, 12.1, and 8.4 ppb, respectively), with a mean value of 2770 ± 120 Ma in agreement with the Kuittila molybdenite age. The Re and 187Os abundances in these three pyrite splits are highly correlated (r = 0.9994), and provide a 187Re-187Os isochron age of 2607 ± 47 Ma with an intercept of 21 ppt 187Os (MSWD = 1.1). It appears

  3. Rock History and Culture

    OpenAIRE

    Gonzalez, Éric

    2013-01-01

    Two ambitious works written by French-speaking scholars tackle rock music as a research object, from different but complementary perspectives. Both are a definite must-read for anyone interested in the contextualisation of rock music in western popular culture. In Une histoire musicale du rock (i.e. A Musical History of Rock), rock music is approached from the point of view of the people – musicians and industry – behind the music. Christophe Pirenne endeavours to examine that field from a m...

  4. The Importance of Transition Metals in the Expanding Network of Microbial Metabolism in the Archean Eon

    Science.gov (United States)

    Moore, E. K.; Jelen, B. I.; Giovannelli, D.; Prabhu, A.; Raanan, H.; Falkowski, P. G.

    2017-12-01

    Deep time changes in Earth surface redox conditions, particularly due to global oxygenation, has impacted the availability of different metals and substrates that are central in biology. Oxidoreductase proteins are molecular nanomachines responsible for all biological electron transfer processes across the tree of life. These enzymes largely contain transition metals in their active sites. Microbial metabolic pathways form a global network of electron transfer, which expanded throughout the Archean eon. Older metabolisms (sulfur reduction, methanogenesis, anoxygenic photosynthesis) accessed negative redox potentials, while later evolving metabolisms (oxygenic photosynthesis, nitrification/denitrification, aerobic respiration) accessed positive redox potentials. The incorporation of different transition metals facilitated biological innovation and the expansion of the network of microbial metabolism. Network analysis was used to examine the connections between microbial taxa, metabolic pathways, crucial metallocofactors, and substrates in deep time by incorporating biosignatures preserved in the geologic record. Nitrogen fixation and aerobic respiration have the highest level of betweenness among metabolisms in the network, indicating that the oldest metabolisms are not the most central. Fe has by far the highest betweenness among metals. Clustering analysis largely separates High Metal Bacteria (HMB), Low Metal Bacteria (LMB), and Archaea showing that simple un-weighted links between taxa, metabolism, and metals have phylogenetic relevance. On average HMB have the highest betweenness among taxa, followed by Archaea and LMB. There is a correlation between the number of metallocofactors and metabolic pathways in representative bacterial taxa, but Archaea do not follow this trend. In many cases older and more recently evolved metabolisms were clustered together supporting previous findings that proliferation of metabolic pathways is not necessarily chronological.

  5. The extant shore platform stromatolite (SPS facies association: a glimpse into the Archean?

    Directory of Open Access Journals (Sweden)

    A. Smith

    2018-04-01

    Full Text Available Shore platform stromatolites (SPS were first noted at Cape Morgan on the south-east African seaboard. Since then they have been found growing discontinuously in rocky peritidal zones along the entire southern African seaboard. They have also been found on the southwest Australian coast, at Giant's Causeway in Northern Ireland, and more recently at Harris on the Scottish Hebridean Atlantic coast. In this paper SPS occurrence and SPS potential as analogues for Precambrian fossil stromatolites, as well as potential stromatolite occurrences in shore platform regions on Mars, are assessed. Sub-horizontal surfaces promote stromatolite development, while tufa develops on cliffs and steep rocky surfaces. Tufa and stromatolites are end members of a spectrum dictated by coastal topography. Extant SPS occur on well indurated shore platforms in high wave energy settings, often around or near headlands. They can be associated with boulder beaches, boulder ridges, storm swash terraces, coastal dunes, and peat bogs. In contrast to other extant stromatolites, SPS are produced primarily by mineral precipitation, although minor trapping and binding stromatolites do occur. From a geological perspective, SPS develop in mildly transgressive siliciclastic settings in various climatic and tidal regimes. We suggest that SPS could be preserved in the geological record as micritic lenses on palaeo-shore platform surfaces. SPS share many features with Precambrian stromatolites and are a valid modern analogue despite the widely different atmospheric and oceanic conditions of the Archean. We suggest that terraces associated with former oceanic or lacustrine flooding surfaces on Mars are potential targets in the search for palaeo-SPS on Mars.

  6. U-Pb zircon geochronology and Sm-Nd-Pb isotopic constraint for precambrian plutonic rocks in the northeastern part of Ryeongnam massif, Korea

    International Nuclear Information System (INIS)

    Chang, Ho-Wan

    2003-01-01

    The Ryeongnam massif is composed of Precambrian gneisses, Paleozoic and Mesozoic sedimentary rocks and extensive Triassic-Jurassic plutonic rocks of felsic to mafic composition. In the northeast Ryeongnam massif, the oldest rocks belong to the Sobaegsan gneiss complex, which is composed of orthogneisses, paragneisses and mafic plutonic rocks. U-Pb zircon ages for the felsic and mafic intrusive bodies within the Sobaegsan gneiss complex are: the Icheon granite gneiss, 2357±43 and 2342±47 Ma; the Buncheon granite gneiss, 1963±5 Ma; the Pyeonghae granite gneiss, 1936±21 Ma; the Ogbang amphibolite, 1918±10 Ma; the Imwon leucogranite gneiss, 1826±20 Ma. The Hyeondong biotite schist, which is intruded by the Buncheon granite gneiss and the Ogbang amphibolite, yielded an age of 2271±44 Ma. The Nd-Sm-Pb isotopic data indicate that the felsic plutonic rocks are derived from an older Archean crust. The Nd T DM ages are Archean, and the εNd values are negative for the felsic rocks and positive for the amphibolite. Common Pb isotope compositions also indicate a crustal source for the felsic intrusives. The U-Pb ages of Precambrian rocks of the Ryeongnam massifs are similar to those in the Gyeonggi massif, and may have a similar crustal evolutionary history. The Precambrian rocks of South Korea could be related either to the North China block or to the South China block, as the isotope ages and patterns are not unique to either block. Similarly, a geologic correlation with Japan, although possible, is tenuous at present. (author)

  7. Geochemistry, petrography, and zircon U-Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon-Tanana terrane

    Science.gov (United States)

    Dusel-Bacon, Cynthia; Day, Warren C.; Aleinikoff, John N.

    2013-01-01

    We report the results of new mapping, whole-rock major, minor, and trace-element geochemistry, and petrography for metaigneous rocks from the Mount Veta area in the westernmost part of the allochthonous Yukon–Tanana terrane (YTT) in east-central Alaska. These rocks include tonalitic mylonite gneiss and mafic metaigneous rocks from the Chicken metamorphic complex and the Nasina and Fortymile River assemblages. Whole-rock trace-element data from the tonalitic gneiss, whose igneous protolith was dated by SHRIMP U–Pb zircon geochronology at 332.6 ± 5.6 Ma, indicate derivation from tholeiitic arc basalt. Whole-rock analyses of the mafic rocks suggest that greenschist-facies rocks from the Chicken metamorphic complex, a mafic metavolcanic rock from the Nasina assemblage, and an amphibolite from the Fortymile River assemblage formed as island-arc tholeiite in a back-arc setting; another Nasina assemblage greenschist has MORB geochemical characteristics, and another mafic metaigneous rock from the Fortymile River assemblage has geochemical characteristics of calc-alkaline basalt. Our geochemical results imply derivation in an arc and back-arc spreading region within the allochthonous YTT crustal fragment, as previously proposed for correlative units in other parts of the terrane. We also describe the petrography and geochemistry of a newly discovered tectonic lens of Alpine-type metaharzburgite. The metaharzburgite is interpreted to be a sliver of lithospheric mantle from beneath the Seventymile ocean basin or from sub-continental mantle lithosphere of the allochthonous YTT or the western margin of Laurentia that was tectonically emplaced within crustal rocks during closure of the Seventymile ocean basin and subsequently displaced and fragmented by faults.

  8. Archean Isotope Anomalies as a Window into the Differentiation History of the Earth

    Science.gov (United States)

    Wainwright, A. N.; Debaille, V.; Zincone, S. A.

    2018-05-01

    No resolvable µ142Nd anomaly was detected in Paleo- Mesoarchean rocks of São Francisco and West African cratons. The lack of µ142Nd anomalies outside of North America and Greenland implies the Earth differentiated into at least two distinct domains.

  9. 40Ar/39Ar incremental-release ages of biotite from a progressively remetamorphosed Archean basement terrane in southwestern Labrador

    International Nuclear Information System (INIS)

    Dallmeyer, R.D.

    1982-01-01

    Gneisses within Archean basement terrane adjacent to the southwestern portion of the Labrador Trough were variably retrograded during a regional metamorphism of Grenville age (ca. 1000 Ma). Bioties from non-retrograded segments of the gneiss terrane record 40 Ar/ 39 Ar plateau and isochron ages which date times of cooling following an episode of the Kenoran orogeny (2376-2391 Ma). A suite of gneiss samples displaying varying degrees of retrograde alteration was collected across the Grenville metamorphic gradient. Bioties in these samples show no petrographic evidence of retrograde alteration, however they do record internally discordant 40 Ar/ 39 Ar age spectra. Although the extent of internal discordance is variable, the overall character of the release patterns is similar with younger apparent ages recorded in intermediate-temperature gas fractions. The total-gas dates range from 2257+-27 Ma (northwest) to 1751+-23 Ma (southeast), suggesting that variable quantities of radiogenic argon were lost from the Archean biotites during Grenville metamorphism. The 'saddle-shaped' nature of the discordant spectra indicates that argon loss was not accomplished through single-stage, volume diffusion processes. (orig./ME)

  10. 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

    2015-07-01

    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

  11. Detrital Zircon Geochronology of Sedimentary Rocks of the 3.6 - 3.2 Ga Barberton Greenstone Belt: No Evidence for Older Continental Crust

    Science.gov (United States)

    Drabon, N.; Lowe, D. R.; Byerly, G. R.; Harrington, J.

    2017-12-01

    The crustal setting of early Archean greenstone belts and whether they formed on or associated with blocks of older continental crust or in more oceanic settings remains a major issue in Archean geology. We report detrital zircon U-Pb age data from sandstones of the 3.26-3.20 Ga Fig Tree and Moodies Groups and from 3.47 to 3.23 Ga meteorite impact-related deposits in the 3.55-3.20 Ga Barberton greenstone belt (BGB), South Africa. The provenance signatures of these sediments are characterized by zircon age peaks at 3.54, 3.46, 3.40, 3.30, and 3.25 Ga. These clusters are coincident either with the ages of major episodes of felsic to intermediate igneous activity within and around the belt or with the ages of thin felsic tuffs reflecting distant volcanic activity. Only 15 of the reported 3410 grains (old zircons could represent felsic rocks in older, unexposed parts of the BGB sequence, but are too few to provide evidence for a continental source. This finding offers further evidence that the large, thick, high-standing, highly evolved blocks of continental crust with an andesitic bulk composition that characterize the Earth during younger geologic times were scarce in the early Archean.

  12. Rock Cycle Roulette.

    Science.gov (United States)

    Schmidt, Stan M.; Palmer, Courtney

    2000-01-01

    Introduces an activity on the rock cycle. Sets 11 stages representing the transitions of an earth material in the rock cycle. Builds six-sided die for each station, and students move to the stations depending on the rolling side of the die. Evaluates students by discussing several questions in the classroom. Provides instructional information for…

  13. Rock engineering in Finland

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    Contains a large collection of short articles concerned with tunnels and underground caverns and their construction and use. The articles are grouped under the following headings: use of the subsurface space; water supply; waste water services; energy management (includes articles on power stations, district heating and oil storage and an article on coal storage); multipurpose tunnels; waste disposal; transport; shelters; sporting and recreational amenities located in rock caverns; storage facilities; industrial, laboratory, and service facilities; rock foundations; tourism and culture; utilization of rock masses; research on the disposal of nuclear waste; training and research in the field of rock engineering; site investigation techniques; design of structures in rock; construction; the environment and occupational safety; modern equipment technology; underground space in Helsinki.

  14. Archean evolution of Enderby Land (Antarctica) and isotope-geochronological evidences for its ancient history

    International Nuclear Information System (INIS)

    Krylov, D.P.; Belyatskij, B.V.

    1987-01-01

    Revew of published isotope-geochronological data on Ender by Land (Antarctica), which is the region of highly metamorphic formations predominant development which includes ancient rock relicts, is presented. Three tectonic-thermal events present the Archeau evolution in the region. Correlation of isotope-geochronological (U-Pb, Rb-Sr, Sm-Nd) data with micro textural processing allows to estimate tectonic-thermal events age: 3000-3100 about 2900 and about 2500 million years. Metamorphism of 3000-3100 million years age has essentially modified all the isotope systems, while model calculations for evolution of U-Pb, Rb-Sr, Sm-Nd systems have shown that rocks primary formation accurred 3500-3900 million years ago

  15. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life

    OpenAIRE

    Waldbauer, Jacob R.; Newman, Dianne K.; Summons, Roger E.

    2011-01-01

    The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth’s evolution. Among the various geochemical proxies for the presence of O_2 in the environment, molecular fossils offer a unique record of O_2 where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires mo...

  16. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: Is this really archean crust?

    Science.gov (United States)

    Premo, Wayne R.; Castineiras, Pedro; Wooden, Joseph L.

    2008-01-01

    New SHRIMP-RG (sensitive high-resolution ion microprobe-reverse geometry) data confirm the existence of Archean components within zircon grains of a sample from the orthogneiss of Angel Lake, Nevada, United States, previously interpreted as a nappe of Archean crust. However, the combined evidence strongly suggests that this orthogneiss is a highly deformed, Late Cretaceous monzogranite derived from melting of a sedimentary source dominated by Archean detritus. Zircon grains from the same sample used previously for isotope dilution-thermal ionization mass spectrometry (ID-TIMS) isotopic work were analyzed using the SHRIMP-RG to better define the age and origin of the orthogneiss. Prior to analysis, imaging revealed a morphological variability and intragrain, polyphase nature of the zircon population. The SHRIMP-RG yielded 207Pb/206Pb ages between ca. 2430 and 2580 Ma (a best-fit mean 207Pb/206Pb age of 2531 ± 19 Ma; 95% confidence) from mostly rounded to subrounded zircons and zircon components (cores). In addition, several analyses from rounded to subrounded cores or grains yielded discordant 207Pb/206Pb ages between ca. 1460 and ca. 2170 Ma, consistent with known regional magmatic events. All cores of Proterozoic to latest Archean age were encased within clear, typically low Th/U (206Pb/238U ages between 72 and 91 Ma, consistent with magmatic ages from Lamoille Canyon to the south. An age of ca. 90 Ma is suggested, the younger 206Pb/238U ages resulting from Pb loss. The Cretaceous and Precambrian zircon components also have distinct trace element characteristics, indicating that these age groups are not related to the same igneous source. These results support recent geophysical interpretations and negate the contention that the Archean-Proterozoic boundary extends into the central Great Basin area. They further suggest that the world-class gold deposits along the Carlin Trend are not underlain by Archean cratonal crust, but rather by the Proterozoic Mojave

  17. Geochemistry of the Oruatemanu Formation, Arrow Rocks, Northland, New Zealand

    International Nuclear Information System (INIS)

    Hori, R.S.; Higuchi, Y.; Fujiki, T.; Maeda, T.; Ikehara, M.

    2007-01-01

    We investigated the geochemical characteristics of sedimentary rocks from the Upper Permian - Middle Triassic Oruatemanu Formation on Arrow Rocks, Waipapa Terrane, New Zealand. The sedimentary rocks consist of limestone, tuffaceous shale, vari-coloured bedded chert, hemipelagic shale and green siliceous mudstone (= green argillite), in ascending order, a typical oceanic plate sequence. Shale and green argillite have higher Zr/Nb ratios than do chert and tuffaceous shales, and show similar REE patterns to PAAS (Post-Archean average Australian shale). In contrast, chert sequences from the basal part and intercalated tuff layers have high TiO 2 contents and Zr/Nb ratios similar to those of basaltic rocks from Arrow Rocks. These geochemical characteristics suggest that the sedimentary environment of the Oruatemanu Formation changed upward, from an open sea setting to the continental margin of Gondwanaland. Chemical compositions of bedded cherts from Arrow Rocks indicate a mixing of biogenic silica, detritus from continents and basaltic materials. In the interval from Upper Permian to Lower Middle Triassic this mixing shows remarkable secular variations. We detected geochemical signals of two Oceanic Anoxic Events (OAEs), one at the Permian/Triassic (P/T) boundary, and the other at the middle Upper Induan level. We name them the OAEα (P/T OAE) and OAEβ (Upper Induan OAE). These OAE horizons are enriched in S, U and other heavy metals (e.g. Mo and Cr), and also have high V/(V+Ni) ratios. Based on a comparison between enrichment factors of Cr and other redox-sensitive trace elements (e.g. Zn, Pb, Co, Cu), the Upper Induan OAEβ is considered to be more intense than the P/T boundary OAEα. This result is not in agreement with the superanoxia model previously proposed. In addition, OAEβ corresponds well with the radiolarian faunal turnover from Permian to Triassic forms documented from the Oruatemanu Formation in this volume. These results may suggest that peak time and

  18. 182W and HSE constraints from 2.7 Ga komatiites on the heterogeneous nature of the Archean mantle

    Science.gov (United States)

    Puchtel, Igor S.; Blichert-Toft, Janne; Touboul, Mathieu; Walker, Richard J.

    2018-05-01

    While the isotopically heterogeneous nature of the terrestrial mantle has long been established, the origin, scale, and longevity of the heterogeneities for different elements and isotopic systems are still debated. Here, we report Nd, Hf, W, and Os isotopic and highly siderophile element (HSE) abundance data for the Boston Creek komatiitic basalt lava flow (BCF) in the 2.7 Ga Abitibi greenstone belt, Canada. This lava flow is characterized by strong depletions in Al and heavy rare earth elements (REE), enrichments in light REE, and initial ε143Nd = +2.5 ± 0.2 and intial ε176Hf = +4.2 ± 0.9 indicative of derivation from a deep mantle source with time-integrated suprachondritic Sm/Nd and Lu/Hf ratios. The data plot on the terrestrial Nd-Hf array suggesting minimal involvement of early magma ocean processes in the fractionation of lithophile trace elements in the mantle source. This conclusion is supported by a mean μ142Nd = -3.8 ± 2.8 that is unresolvable from terrestrial standards. By contrast, the BCF exhibits a positive 182W anomaly (μ182W = +11.7 ± 4.5), yet is characterized by chondritic initial γ187Os = +0.1 ± 0.3 and low inferred source HSE abundances (35 ± 5% of those estimated for the present-day Bulk Silicate Earth, BSE). Collectively, these characteristics are unique among Archean komatiite systems studied so far. The deficit in the HSE, coupled with the chondritic Os isotopic composition, but a positive 182W anomaly, are best explained by derivation of the parental BCF magma from a mantle domain characterized by a predominance of HSE-deficient, differentiated late accreted material. According to the model presented here, the mantle domain that gave rise to the BCF received only ∼35% of the present-day HSE complement in the BSE before becoming isolated from the rest of the convecting mantle until the time of komatiite emplacement at 2.72 Ga. These new data provide strong evidence for a highly heterogeneous Archean mantle in terms of absolute

  19. High-grade iron ore at Windarling, Yilgarn Craton: a product of syn-orogenic deformation, hypogene hydrothermal alteration and supergene modification in an Archean BIF-basalt lithostratigraphy

    Science.gov (United States)

    Angerer, Thomas; Hagemann, Steffen G.; Danyushevsky, Leonid

    2013-08-01

    Banded iron formation (BIF)-hosted iron ore deposits in the Windarling Range are located in the lower greenstone succession of the Marda-Diemals greenstone belt, Southern Cross domain, Yilgarn Craton and constitute a total hematite-martite-goethite ore resource of minimum 52 Mt at 60 wt.% Fe (0.07 P). Banded iron formation is interlayered with high-Mg basalts at Windarling and precipitated during episodes of volcanic quiescence. Trace element content and the rare earth element (REE) ratios Y/Ho (42 to 45), Sm/Yb (1.5), together with positive La and Gd anomalies in `least-altered' hematite-magnetite-metachert-BIF indicate the precipitation from Archean seawater that was fertilised by hydrothermal vent fluids with a basaltic HREE-Y signature. Hypogene iron ore in sub-greenschist facies metamorphosed BIF formed during three distinct stages: ore stage 1 was a syn- to post-metamorphic, syn-D1, Fe-Ca-Mg-Ni-Co-P-REE metasomatism that produced local Ni-REE-rich Fe-dolomite-magnetite alteration in BIF. Hydrothermal alteration was induced by hot fluid flow controlled by brittle-ductile reactivation of BIF-basalt margins and crosscutting D1 faults. The Ni-Co-rich content of dolomite and a shift in REE ratios in carbonate-altered BIF towards Archean mafic rock signature (Y/Ho to 31 to 40, Sm/Yb to 1 to 2 and Gd/Gd* to 1.2 to 1.4) suggest that high-Mg basalts in the Windarling Range were the primary source of introduced metals. During ore stage 2, a syn-deformational and likely acidic and oxidised fluid flow along BIF-basalt margins and within D1 faults leached carbonate and precipitated lepidoblastic and anhedral/granoblastic hematite. High-grade magnetite-hematite ore is formed during this stage. Ore stage 3 hydrothermal specular hematite (spcH)-Fe-dolomite-quartz alteration was controlled by a late-orogenic, brittle, compressional/transpressional stage (D4; the regional-scale shear-zone-related D3 is not preserved in Windarling). This minor event remobilised iron oxides

  20. Eos Chaos Rocks

    Science.gov (United States)

    2006-01-01

    11 January 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered rock outcrops in Eos Chaos, located near the east end of the Valles Marineris trough system. The outcrops occur in the form of a distinct, circular butte (upper half of image) and a high slope (lower half of image). The rocks might be sedimentary rocks, similar to those found elsewhere exposed in the Valles Marineris system and the chaotic terrain to the east of the region. Location near: 12.9oS, 49.5oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Summer

  1. Stable isotope and fluid inclusion signatures of hydrothermal fluids in transcrustal fault zones: significance for orogenic, Archean lode-gold mineralization

    International Nuclear Information System (INIS)

    Neumayr, P.; Hagemann, S.G.; Groves, D.I.

    1999-01-01

    mil). Calculated d 18 O fluid compositions for quartz in the CTZ range from 8.0 to 10.3 per mil at 350 deg C (based on arsenopyrite and chlorite thermometry). Hydrogen isotopes from fluid inclusion waters trapped in quartz have a large variation from -62.5 per mil to -7.2 per mil in the CTZ fluids, whereas hydrogen in fluid inclusions in quartz in the second- and third-order shear zones shows a restricted range from -67.6 to -39.8 per mil. The oxygen isotope shift of about 2 per mil from the CTZ to the second- and third-order fault zones may be explained by two competing processes: 1) the hydrothermal fluids in the CTZ equilibrated, at least partially, with metasedimentary rocks in the footwall, and or 2) there was fractionation of oxygen isotopes during phase immiscibility of a combined H 2 O-CO 2 fluid. The preferential trapping of CO 2 -rich fluids in the CTZ, and H 2 O-rich fluids in the second- and third-order fault zones, therefore, could account for the shift in d 18 O. At present, the first process is preferred, because of the ubiquitous presence of the metasedimentary rocks in the footwall and the consistent d 18 O composition of the CTZ, even in hydrothermal quartz veins which contain significant H 2 O. The large variation in the hydrogen isotopes in fluid inclusions in quartz in the CTZ may be explained by late Archean and post-Archean reactivation of the CTZ and the introduction of fluids related to late-fractures fills, whereas apparently minor reactivation of the second- and third-order structures resulted in a restricted range of dD. Copyright (1999) Geological Society of Australia

  2. Rock properties data base

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, R.; Gorski, B.; Gyenge, M.

    1991-03-01

    As mining companies proceed deeper and into areas whose stability is threatened by high and complex stress fields, the science of rock mechanics becomes invaluable in designing underground mine strata control programs. CANMET's Mining Research Laboratories division has compiled a summary of pre- and post-failure mechanical properties of rock types which were tested to provide design data. The 'Rock Properties Data Base' presents the results of these tests, and includes many rock types typical of Canadian mine environments. The data base also contains 'm' and 's' values determined using Hoek and Brown's failure criteria for both pre- and post-failure conditions. 7 refs., 3 tabs., 9 figs., 1 append.

  3. Eclogite facies rocks

    National Research Council Canada - National Science Library

    Carswell, D. A

    1990-01-01

    ... of eclogite evolution and genesis. The authors present a thorough treatment of the stability relations and geochemistry of these rocks, their intimate association with continental plate collision zones and suture zones...

  4. Rock kinoekraanil / Katrin Rajasaare

    Index Scriptorium Estoniae

    Rajasaare, Katrin

    2008-01-01

    7.-11. juulini kinos Sõprus toimuval filminädalal "Rock On Screen" ekraanile jõudvatest rockmuusikuid portreteerivatest filmidest "Lou Reed's Berlin", "The Future Is Unwritten: Joe Strummer", "Control: Joy Division", "Hurriganes", "Shlaager"

  5. Eclogite facies rocks

    National Research Council Canada - National Science Library

    Carswell, D. A

    1990-01-01

    .... This is the first volume to provide a coherent and comprehensive review of the conditions necessary for the formation of eclogites and eclogite facies rocks and assemblages, and a detailed account...

  6. Solid as a rock

    International Nuclear Information System (INIS)

    Pincus, H.J.

    1984-01-01

    Recent technologic developments have required a more comprehensive approach to the behavior of rock mass or rock substance plus discontinuities than was adequate previously. This work considers the inherent problems in such operations as the storage of hot or cold fluids in caverns and aquifers, underground storage of nuclear waste, underground recovery of heat from hydrocarbon fuels, tertiary recovery of oil by thermal methods, rapid excavation of large openings at shallow to great depths and in hostile environments, and retrofitting of large structures built on or in rock. The standardization of methods for determining rock properties is essential to all of the activities described, for use not only in design and construction but also in site selection and post-construction monitoring. Development of such standards is seen as a multidisciplinary effort

  7. Rock Equity Holdings, LLC

    Science.gov (United States)

    The EPA is providing notice of an Administrative Penalty Assessment in the form of an Expedited Storm Water Settlement Agreement against Rock Equity Holdings, LLC, for alleged violations at The Cove at Kettlestone/98th Street Reconstruction located at 3015

  8. Pop & rock / Berk Vaher

    Index Scriptorium Estoniae

    Vaher, Berk, 1975-

    2001-01-01

    Uute heliplaatide Redman "Malpractice", Brian Eno & Peter Schwalm "Popstars", Clawfinger "A Whole Lot of Nothing", Dario G "In Full Color", MLTR e. Michael Learns To Rock "Blue Night" lühitutvustused

  9. Updating the Geologic Barcodes for South China: Discovery of Late Archean Banded Iron Formations in the Yangtze Craton.

    Science.gov (United States)

    Ye, Hui; Wu, Chang-Zhi; Yang, Tao; Santosh, M; Yao, Xi-Zhu; Gao, Bing-Fei; Wang, Xiao-Lei; Li, Weiqiang

    2017-11-08

    Banded iron formations (BIFs) in Archean cratons provide important "geologic barcodes" for the global correlation of Precambrian sedimentary records. Here we report the first finding of late Archean BIFs from the Yangtze Craton, one of largest Precambrian blocks in East Asia with an evolutionary history of over 3.3 Ga. The Yingshan iron deposit at the northeastern margin of the Yangtze Craton, displays typical features of BIF, including: (i) alternating Si-rich and Fe-rich bands at sub-mm to meter scales; (ii) high SiO 2  + Fe 2 O 3total contents (average 90.6 wt.%) and Fe/Ti ratios (average 489); (iii) relative enrichment of heavy rare earth elements and positive Eu anomalies (average 1.42); (iv) and sedimentary Fe isotope compositions (δ 56 Fe IRMM-014 as low as -0.36‰). The depositional age of the BIF is constrained at ~2464 ± 24 Ma based on U-Pb dating of zircon grains from a migmatite sample of a volcanic protolith that conformably overlied the Yingshan BIF. The BIF was intruded by Neoproterozoic (805.9 ± 4.7 Ma) granitoids that are unique in the Yangtze Craton but absent in the North China Craton to the north. The discovery of the Yingshan BIF provides new constraints for the tectonic evolution of the Yangtze Craton and has important implications in the reconstruction of Pre-Nuna/Columbia supercontinent configurations.

  10. Pb-Pb and U-Pb zircon ages of archean syntetocnic granites of the Carajas metallogenic province, northern Brazil

    International Nuclear Information System (INIS)

    Barros, Carlos Eduardo de Mesquita; Sardinha, Alex Souza; Barbosa, Jaime dos Passos de Oliveira; Krimski, Robert; Macambira, Moacir Jose Buenano

    2001-01-01

    The Carajas Metallogenic Province is located in the southeastern Amazonian Craton. It has been divided in two domains, the southernmost comprises the Rio Maria region and the northernmost corresponds to Caraj region (Souza et al. 1996). The former domain is made up of Archean greenstone sequences (2,97 Ga), TTG (2,9 Ga) and calc-alkaline granitoids (2,87 Ga) (Macambira and Lafon 1995, Leite et al. 1999, Althoff et al. 2000). The Carajas block is constituted of minor mafic granulites (3,00 Ga) and quartzofeldspathic gneisses (2,81 Ga), metavolcanosedimentary sequences (2,76 Ga) and granites (2,76 to 2,56 Ga) (Machado et al. 1991; Huhn et al. 1999, Pidgeon et al. 2000). Widespread anorogenic A-type granites are found in both areas (Docegeo 1988; Dall'Agnol et al. 1994). In the last two decades several authors (Lindenamyer et al. 1994, Barros and Barbey 1998, Huhn et al. 1999 and others) have emphasized the role of the Archean granite magmatism in the tectonicthermal evolution in the Carajas Province. In this paper we discuss the tectonic significance of the Pb- Pb and U-Pb ages obtained in some granitoids from the Carajas region. The Estrela Granite Complex and the granitoids located to the north of Parauapebas were dated by Pb- Pb evaporation zircon method (cf. Kober 1987). Data are presented considering 2σ ∼ . The Pb corrections have been done in the basis of the evolution model of Pb in double stage (cf. Stacey and Kramers 1975). U-Pb zircon method (cf. Krogh 1973, Stacey and Kramers 1975, Parrish 1987, Ludwuig 1999), recently put on routine in the Para-Iso laboratories, was employed to date the granite from the Serra do Rabo area. Analyses were carried on the Finnigan Mat 262 spectrometer (au)

  11. Weathering of rock 'Ginger'

    Science.gov (United States)

    1997-01-01

    One of the more unusual rocks at the site is Ginger, located southeast of the lander. Parts of it have the reddest color of any material in view, whereas its rounded lobes are gray and relatively unweathered. These color differences are brought out in the inset, enhanced at the upper right. In the false color image at the lower right, the shape of the visible-wavelength spectrum (related to the abundance of weathered ferric iron minerals) is indicated by the hue of the rocks. Blue indicates relatively unweathered rocks. Typical soils and drift, which are heavily weathered, are shown in green and flesh tones. The very red color in the creases in the rock surface correspond to a crust of ferric minerals. The origin of the rock is uncertain; the ferric crust may have grown underneath the rock, or it may cement pebbles together into a conglomerate. Ginger will be a target of future super-resolution studies to better constrain its origin.Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. JPL is an operating division of the California Institute of Technology (Caltech).

  12. Oxidative release of chromium from Archean ultramafic rocks, its transport and environmental impact – A Cr isotope perspective on the Sukinda valley ore district (Orissa, India)

    DEFF Research Database (Denmark)

    Paulukat, Cora Stefanie; Døssing, Lasse Nørbye; Mondal, Sisir K.

    2015-01-01

    to negatively fractionated values as low as δ53Cr = −1.29 ± 0.04‰. Local surface waters are isotopically heavy relative to the soils. This supports the hypothesis that during oxidative weathering isotopically heavy Cr(VI) is leached from the soils to runoff. The impact of mining pollution is observed downstream...... in controlling the hazardous impact of Cr(VI) on health and environment. The positive Cr isotope signatures of the Brahmani estuary and coastal seawater collected from the Bay of Bengal further indicate that the positively fractionated Cr isotope signal from the catchment area is preserved during its transport...

  13. Deciphering igneous and metamorphic events in high-grade rocks of the Wilmington complex, Delaware: Morphology, cathodoluminescence and backscattered electron zoning, and SHRIMP U-Pb geochronology of zircon and monazite

    Science.gov (United States)

    Aleinikoff, J.N.; Schenck, W.S.; Plank, M.O.; Srogi, L.A.; Fanning, C.M.; Kamo, S.L.; Bosbyshell, H.

    2006-01-01

    High-grade rocks of the Wilmington Complex, northern Delaware and adjacent Maryland and Pennsylvania, contain morphologically complex zircons that formed through both igneous and metamorphic processes during the development of an island-arc complex and suturing of the arc to Laurentia. The arc complex has been divided into several members, the protoliths of which include both intrusive and extrusive rocks. Metasedimentary rocks are interlayered with the complex and are believed to be the infrastructure upon which the arc was built. In the Wilmingto n Complex rocks, both igneous and metamorphic zircons occur as elongate and equant forms. Chemical zoning, shown by cathodoluminescence (CL), includes both concentric, oscillatory patterns, indicative of igneous origin, and patchwork and sector patterns, suggestive of metamorphic growth. Metamorphic monazites are chemically homogeneous, or show oscillatory or spotted chemical zoning in backscattered electron images. U-Pb geochronology by sensitive high resolution ion microprobe (SHRIMP) was used to date complexly zoned zircon and monazite. All but one member of the Wilmington Complex crystallized in the Ordovician between ca. 475 and 485 Ma; these rocks were intruded by a suite of gabbro-to-granite plutonic rocks at 434 ?? Ma. Detrital zircons in metavolcanic and metasedimentary units were derived predominantly from 0.9 to 1.4 Ga (Grenvillian) basement, presumably of Laurentian origin. Amphibolite to granulite facies metamorphism of the Wilmington Complex, recorded by ages of metamorphic zircon (428 ?? 4 and 432 ?? 6 Ma) and monazite (429 ?? 2 and 426 ?? 3 Ma), occurred contemporaneously with emplacement of the younger plutonic rocks. On the basis of varying CL zoning patterns and external morphologies, metamorphic zircons formed by different processes (presumably controlled by rock chemistry) at slightly different times and temperatures during prograde metamorphism. In addition, at least three other thermal episodes are

  14. Transporting radioactive rock

    International Nuclear Information System (INIS)

    Pearce, G.

    1990-01-01

    The case is made for exempting geological specimens from the IAEA Regulations for Safer Transport of Radioactive Materials. It is pointed out that many mineral collectors in Devon and Cornwall may be unwittingly infringing these regulations by taking naturally radioactive rocks and specimens containing uranium ores. Even if these collectors are aware that these rocks are radioactive, and many are not, few have the necessary equipment to monitor the activity levels. If the transport regulations were to be enforced alarm could be generated and the regulations devalued in case of an accident. The danger from a spill of rock specimens is negligible compared with an accident involving industrial or medical radioactive substances yet would require similar special treatment. (UK)

  15. Geotechnical properties of rock

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, R.; Gorski, B.; Gyenge, M.

    1995-12-31

    The manual is a compilation of the geotechnical properties of many types of rock that are typical of Canadian mining environments. Included are values for density, porosity, compressive and shear wave velocity, uniaxial compressive strength, Young`s modulus, and Poisson`s ratio. The data base contains material constants that were determined using the Hoek and Brown failure criteria for both before and after failure conditions. 76 data sheets of rock properties in Canadian mines are included. 7 refs., 85 figs., 3 tabs.

  16. Rock engineering applications, 1991

    International Nuclear Information System (INIS)

    Franklin, J.A.; Dusseault, M.B.

    1991-01-01

    This book demonstrates how to apply the theories and principles of rock engineering to actual engineering and construction tasks. It features insights on geology for mining and tunnelling applications. It is practical resource that focuses on the latest technological innovation and examines up-to-date procedures used by engineers for coping with complex rock conditions. The authors also discuss question related to underground space, from design approaches to underground housing and storage. And they cover the monitoring of storage caverns for liquid and gaseous products or toxic and radioactive wastes

  17. Smart Rocking Armour Units

    OpenAIRE

    Hofland, B.; Arefin, Syed Shamsil; van der Lem, Cock; van gent, Marcel

    2018-01-01

    This paper describes a method to measure the rocking motion of lab-scale armour units. Sensors as found in mobile phones are used. These sensors, data-storage and battery are all embedded in the model units, such that they can be applied without wires attached to them. The technique is applied to double-layer units in order to compare the results to the existing knowledge for this type of armour layers. In contrast to previous research, the gyroscope reading is used to determine the (rocking)...

  18. Rock Hellsinki, Marketing Research

    OpenAIRE

    Todd, Roosa; Jalkanen, Katariina

    2013-01-01

    This paper is a qualitative research about rock and heavy metal music tourism in the capital city of Finland, Helsinki. As Helsinki can be considered the city of contrasts, the silent nature city mixed with urban activities, it is important to also use the potential of the loud rock and heavy metal music contrasting the silence. Finland is known abroad for bands such as HIM, Nightwish, Korpiklaani and Children of Bodom so it would make sense to utilize these in the tourism sector as well. The...

  19. Decoding mass-independent fractionation of sulfur isotopes in modern atmosphere using cosmogenic 35S: A five-isotope approach and possible implications for Archean sulfur isotope records

    Science.gov (United States)

    Lin, M.; Thiemens, M. H.; Shen, Y.; Zhang, X.; Huang, X.; Chen, K.; Zhang, Z.; Tao, J.

    2017-12-01

    The signature of sulfur isotopic mass-independent fractionation (S-MIF) observed in Archean sediments have been interpreted as a proxy of the origins and evolution of atmospheric oxygen and early life on Earth [1]. Photochemistry of SOx in the short (negative Δ36S. After eliminating combustion impacts, the obtained Δ36S/Δ33S slope of -4.0 in the modern atmosphere is close to the Δ36S/Δ33S slope (-3.6) in some records from Paleoarchean [4], an era probably with active volcanism [5]. The significant role of volcanic OCS in the Archean atmosphere has been called for in terms of its ability to provide a continual SO2 high altitude source for photolysis [2]. The strong but previously underappreciated stratospheric signature of S-MIF in tropospheric sulfates suggests that a more careful investigation of wavelength-dependent sulfur isotopic fractionation at different altitudes are required. The combustion-induced negative Δ36S may be linked to recombination reactions of elemental sulfur [6], and relevant experiments are being conducted to test the isotope effect. Although combustion is unlikely in Archean, recombination reactions may occur in other previously unappreciated processes such as volcanism and may contribute in part to the heavily depleted 36S in some Paleoarchean records [5,7]. The roles of both photochemical and non-photochemical reactions in the variability of Archean S-MIF records require further analysis in the future. Refs: [1] Farquhar et al., Science 2000; [2] Shaheen et al., PNAS 2014; [3] Lin et al., PNAS 2016; [4] Wacey et al., Precambrian Res 2015; [5] Muller et al., PNAS 2016; [6] Babikov, PNAS 2017; [7] Shen et al., EPSL, 2009.

  20. A Rock Retrospective.

    Science.gov (United States)

    O'Grady, Terence J.

    1979-01-01

    The author offers an analysis of musical techniques found in the major rock trends of the 1960s. An annotated list of selected readings and a subject-indexed list of selected recordings are appended. This article is part of a theme issue on popular music. (Editor/SJL)

  1. Rock-hard coatings

    OpenAIRE

    Muller, M.

    2007-01-01

    Aircraft jet engines have to be able to withstand infernal conditions. Extreme heat and bitter cold tax coatings to the limit. Materials expert Dr Ir. Wim Sloof fits atoms together to develop rock-hard coatings. The latest invention in this field is known as ceramic matrix composites. Sloof has signed an agreement with a number of parties to investigate this material further.

  2. Fluids in metamorphic rocks

    NARCIS (Netherlands)

    Touret, J.L.R.

    2001-01-01

    Basic principles for the study of fluid inclusions in metamorphic rocks are reviewed and illustrated. A major problem relates to the number of inclusions, possibly formed on a wide range of P-T conditions, having also suffered, in most cases, extensive changes after initial trapping. The

  3. Rock-hard coatings

    NARCIS (Netherlands)

    Muller, M.

    2007-01-01

    Aircraft jet engines have to be able to withstand infernal conditions. Extreme heat and bitter cold tax coatings to the limit. Materials expert Dr Ir. Wim Sloof fits atoms together to develop rock-hard coatings. The latest invention in this field is known as ceramic matrix composites. Sloof has

  4. Northeast Church Rock Mine

    Science.gov (United States)

    Northeast Church Rock Mine, a former uranium mine 17 miles northeast of Gallup, NM in the Pinedale Chapter of the Navajo Nation. EPA is working with NNEPA to oversee cleanup work by United Nuclear Corporation, a company owned by General Electric (GE).

  5. Smart Rocking Armour Units

    NARCIS (Netherlands)

    Hofland, B.; Arefin, Syed Shamsil; van der Lem, Cock; van gent, Marcel

    2018-01-01

    This paper describes a method to measure the rocking motion of lab-scale armour units. Sensors as found in mobile phones are used. These sensors, data-storage and battery are all embedded in the model units, such that they can be applied without wires attached to them. The technique is applied to

  6. Teaching the Rock Cycle with Ease.

    Science.gov (United States)

    Bereki, Debra

    2000-01-01

    Describes a hands-on lesson for teaching high school students the concept of the rock cycle using sedimentary, metamorphic, and igneous rocks. Students use a rock cycle diagram to identify pairs of rocks. From the rock cycle, students explain on paper how their first rock became the second rock and vice versa. (PVD)

  7. For Those About to Rock : Naislaulajat rock-genressä

    OpenAIRE

    Herranen, Linda

    2015-01-01

    For those about to rock – naislaulajat rock-genressä antaa lukijalleen kokonaisvaltaisen käsityksen naisista rock-genressä: rockin historiasta, sukupuolittuneisuudesta, seksismistä, suomalaisten naislaulajien menestyksestä. Työn aineisto on koottu aihepiirin kirjallisuudesta ja alalla toimiville naislaulajille teetettyjen kyselyiden tuloksista. Lisäksi avaan omia kokemuksiani ja ajatuksiani, jotta näkökulma naisista rock-genressä tulisi esille mahdollisimman monipuolisesti. Ajatus aihees...

  8. Comparison of disposal concepts for rock salt and hard rock

    International Nuclear Information System (INIS)

    Papp, R.

    1998-01-01

    The study was carried out in the period 1994-1996. The goals were to prepare a draft on spent fuel disposal in hard rock and additionally a comparison with existing disposal concepts for rock salt. A cask for direct disposal of spent fuel and a repository for hard rock including a safeguards concept were conceptually designed. The results of the study confirm, that the early German decision to employ rock salt was reasonable. (orig.)

  9. Elastic Rock Heterogeneity Controls Brittle Rock Failure during Hydraulic Fracturing

    Science.gov (United States)

    Langenbruch, C.; Shapiro, S. A.

    2014-12-01

    For interpretation and inversion of microseismic data it is important to understand, which properties of the reservoir rock control the occurrence probability of brittle rock failure and associated seismicity during hydraulic stimulation. This is especially important, when inverting for key properties like permeability and fracture conductivity. Although it became accepted that seismic events are triggered by fluid flow and the resulting perturbation of the stress field in the reservoir rock, the magnitude of stress perturbations, capable of triggering failure in rocks, can be highly variable. The controlling physical mechanism of this variability is still under discussion. We compare the occurrence of microseismic events at the Cotton Valley gas field to elastic rock heterogeneity, obtained from measurements along the treatment wells. The heterogeneity is characterized by scale invariant fluctuations of elastic properties. We observe that the elastic heterogeneity of the rock formation controls the occurrence of brittle failure. In particular, we find that the density of events is increasing with the Brittleness Index (BI) of the rock, which is defined as a combination of Young's modulus and Poisson's ratio. We evaluate the physical meaning of the BI. By applying geomechanical investigations we characterize the influence of fluctuating elastic properties in rocks on the probability of brittle rock failure. Our analysis is based on the computation of stress fluctuations caused by elastic heterogeneity of rocks. We find that elastic rock heterogeneity causes stress fluctuations of significant magnitude. Moreover, the stress changes necessary to open and reactivate fractures in rocks are strongly related to fluctuations of elastic moduli. Our analysis gives a physical explanation to the observed relation between elastic heterogeneity of the rock formation and the occurrence of brittle failure during hydraulic reservoir stimulations. A crucial factor for understanding

  10. Range sections as rock models for intensity rock scene segmentation

    CSIR Research Space (South Africa)

    Mkwelo, S

    2007-11-01

    Full Text Available This paper presents another approach to segmenting a scene of rocks on a conveyor belt for the purposes of measuring rock size. Rock size estimation instruments are used to monitor, optimize and control milling and crushing in the mining industry...

  11. Soil/Rock Properties Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Soil/Rock Properties LaboratoryLocation: Spokane SiteThe Soil/Rock Properties Laboratory is contained in the soils bay, a 4,700 sq. ft. facility that provides space...

  12. The magmatic model for the origin of Archean Au-quartz vein ore systems: an assessment of the evidence

    International Nuclear Information System (INIS)

    Spooner, E.T.C.

    1991-01-01

    The magmatic model for the origin of Archean Au-quartz vein ore systems suggests that Au was derived by partition between silicate (± sulphide) melts of certain compositions and H 2 O-CO 2 -NaCl magmatic fluids. Supporting evidence includes partial/structural geological relationships, timing relationships, H and C isotope geochemistry, probable primary Au enrichment in the Lamaque stocks, and fluid inclusion volatile geochemistry. Evidence is currently negative with respect to various within- and sub-greenstone belt metamorphic/deep crustal fluid models for primary Au mineralization; however a U-Pb age for vein stage 3 sphene from the Camflo deposit, Quebec which is ∼ 55-60 Ma younger than the host stock at 2685-2680 Ma indicates dissolution/reprecipitation of Au by late, (?) upper crustal saline fluids. Evidence is accumulating that epithermal-meso thermal Au-Ag mineralization in island arc and cordilleran settings may also have been magmatically derived ± high level fluid mixing from calc-alkaline, shoshonitic and other igneous compositions. (author)

  13. Critical issues in soft rocks

    OpenAIRE

    Milton Assis Kanji

    2014-01-01

    This paper discusses several efforts made to study and investigate soft rocks, as well as their physico-mechanical characteristics recognized up to now, the problems in their sampling and testing, and the possibility of its reproduction through artificially made soft rocks. The problems in utilizing current and widespread classification systems to some types of weak rocks are also discussed, as well as other problems related to them. Some examples of engineering works in soft rock or in soft ...

  14. Isotope shifting capacity of rock

    International Nuclear Information System (INIS)

    Blattner, P.; Department of Scientific and Industrial Research, Lower Hutt

    1980-01-01

    Any oxygen isotope shifted rock volume exactly defines a past throughput of water. An expression is derived that relates the throughput of an open system to the isotope shift of reservoir rock and present-day output. The small isotope shift of Ngawha reservoir rock and the small, high delta oxygen-18 output are best accounted for by a magmatic water source

  15. Rock burst governance of working face under igneous rock

    Science.gov (United States)

    Chang, Zhenxing; Yu, Yue

    2017-01-01

    As a typical failure phenomenon, rock burst occurs in many mines. It can not only cause the working face to cease production, but also cause serious damage to production equipment, and even result in casualties. To explore how to govern rock burst of working face under igneous rock, the 10416 working face in some mine is taken as engineering background. The supports damaged extensively and rock burst took place when the working face advanced. This paper establishes the mechanical model and conducts theoretical analysis and calculation to predict the fracture and migration mechanism and energy release of the thick hard igneous rock above the working face, and to obtain the advancing distance of the working face when the igneous rock fractures and critical value of the energy when rock burst occurs. Based on the specific conditions of the mine, this paper put forward three kinds of governance measures, which are borehole pressure relief, coal seam water injection and blasting pressure relief.

  16. Uranium in alkaline rocks

    International Nuclear Information System (INIS)

    Murphy, M.; Wollenberg, H.; Strisower, B.; Bowman, H.; Flexser, S.; Carmichael, I.

    1978-04-01

    Geologic and geochemical criteria were developed for the occurrence of economic uranium deposits in alkaline igneous rocks. A literature search, a limited chemical analytical program, and visits to three prominent alkaline-rock localities (Ilimaussaq, Greenland; Pocos de Caldas, Brazil; and Powderhorn, Colorado) were made to establish criteria to determine if a site had some uranium resource potential. From the literature, four alkaline-intrusive occurrences of differing character were identified as type-localities for uranium mineralization, and the important aspects of these localities were described. These characteristics were used to categorize and evaluate U.S. occurrences. The literature search disclosed 69 U.S. sites, encompassing nepheline syenite, alkaline granite, and carbonatite. It was possible to compare two-thirds of these sites to the type localities. A ranking system identified ten of the sites as most likely to have uranium resource potential

  17. Rock solidification method

    International Nuclear Information System (INIS)

    Nakaya, Iwao; Murakami, Tadashi; Miyake, Takafumi; Funakoshi, Toshio; Inagaki, Yuzo; Hashimoto, Yasuhide.

    1985-01-01

    Purpose: To convert radioactive wastes into the final state for storage (artificial rocks) in a short period of time. Method: Radioactive burnable wastes such as spent papers, cloths and oils and activated carbons are burnt into ashes in a burning furnace, while radioactive liquid wastes such as liquid wastes of boric acid, exhausted cleaning water and decontaminating liquid wastes are powderized in a drying furnace or calcining furnace. These powders are joined with silicates as such as white clay, silica and glass powder and a liquid alkali such as NaOH or Ca(OH) 2 and transferred to a solidifying vessel. Then, the vessel is set to a hydrothermal reactor, heated and pressurized, then taken out about 20 min after and tightly sealed. In this way, radioactive wastes are converted through the hydrothermal reactions into aqueous rock stable for a long period of time to obtain solidification products insoluble to water and with an extremely low leaching rate. (Ikeda, J.)

  18. Uranium in alkaline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M.; Wollenberg, H.; Strisower, B.; Bowman, H.; Flexser, S.; Carmichael, I.

    1978-04-01

    Geologic and geochemical criteria were developed for the occurrence of economic uranium deposits in alkaline igneous rocks. A literature search, a limited chemical analytical program, and visits to three prominent alkaline-rock localities (Ilimaussaq, Greenland; Pocos de Caldas, Brazil; and Powderhorn, Colorado) were made to establish criteria to determine if a site had some uranium resource potential. From the literature, four alkaline-intrusive occurrences of differing character were identified as type-localities for uranium mineralization, and the important aspects of these localities were described. These characteristics were used to categorize and evaluate U.S. occurrences. The literature search disclosed 69 U.S. sites, encompassing nepheline syenite, alkaline granite, and carbonatite. It was possible to compare two-thirds of these sites to the type localities. A ranking system identified ten of the sites as most likely to have uranium resource potential.

  19. Rock and mineral magnetism

    CERN Document Server

    O’Reilly, W

    1984-01-01

    The past two decades have witnessed a revolution in the earth sciences. The quantitative, instrument-based measurements and physical models of. geophysics, together with advances in technology, have radically transformed the way in which the Earth, and especially its crust, is described. The study of the magnetism of the rocks of the Earth's crust has played a major part in this transformation. Rocks, or more specifically their constituent magnetic minerals, can be regarded as a measuring instrument provided by nature, which can be employed in the service of the earth sciences. Thus magnetic minerals are a recording magnetometer; a goniometer or protractor, recording the directions of flows, fields and forces; a clock; a recording thermometer; a position recorder; astrain gauge; an instrument for geo­ logical surveying; a tracer in climatology and hydrology; a tool in petrology. No instrument is linear, or free from noise and systematic errors, and the performance of nature's instrument must be assessed and ...

  20. Paleoproterozoic mojaveprovince in northwestern Mexico? Isotopic and U-Pb zircon geochronologic studies of precambrian and Cambrian crystalline and sedimentary rocks, Caborca, Sonora

    Science.gov (United States)

    Lang, Farmer G.; Bowring, S.A.; Matzel, J.; Maldonado, G.E.; Fedo, C.; Wooden, J.

    2005-01-01

    Whole-rock Nd isotopic data and U-Pb zircon geochronology from Precambrian crystalline rocks in the Caborca area, northern Sonora, reveal that these rocks are most likely a segment of the Paleoproterozoic Mojave province. Supporting this conclusion are the observations that paragneiss from the ??? 1.75 Ga Bamori Complex has a 2.4 Ga Nd model age and contains detrital zircons ranging in age from Paleo- proterozoic (1.75 Ga) to Archean (3.2 Ga). Paragneisses with similar age and isotopic characteristics occur in the Mojave province in southern California. In addition, "A-type" granite exposed at the southern end of Cerro Rajon has ca 2.0 Ga Nd model age and a U-Pb zircon age of 1.71 Ga, which are similar to those of Paleoproterozoic granites in the Mojave province. Unlike the U.S. Mojave province, the Caborcan crust contains ca. 1.1 Ga granite (Aibo Granite), which our new Nd isotopic data suggest is largely the product of anatexis of the local Precambrian basement. Detrital zircons from Neoproterozoic to early Cambrian miogeoclinal arenites at Caborca show dominant populations ca. 1.7 Ga, ca. 1.4 Ga, and ca. 1.1 Ga, with subordinate Early Cambrian and Archean zircons. These zircons were likely derived predominately from North American crust to the east and northeast, and not from the underlying Caborcan basement. The general age and isotopic similarities between Mojave province basement and overlying miogeoclinal sedimentary rocks in Sonora and southern California is necessary, but not sufficient, proof of the hypothesis that Sonoran crust is allochthonous and was transported to its current position during the Mesozoic along the proposed Mojave-Sonora megashear. One viable alternative model is that the Caborcan Precambrian crust is an isolated, autochthonous segment of Mojave province crust that shares a similar, but not identical, Proterozoic geological history with Mojave province crust found in the southwest United States ?? 2005 Geological Society of America.

  1. Aram Chaos Rocks

    Science.gov (United States)

    2005-01-01

    8 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcrops of light-toned, sedimentary rock among darker-toned mesas in Aram Chaos. Dark, windblown megaripples -- large ripples -- are also present at this location. Location near: 3.0oN, 21.6oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  2. Deformations of fractured rock

    International Nuclear Information System (INIS)

    Stephansson, O.

    1977-09-01

    Results of the DBM and FEM analysis in this study indicate that a suitable rock mass for repository of radioactive waste should be moderately jointed (about 1 joint/m 2 ) and surrounded by shear zones of the first order. This allowes for a gentle and flexible deformation under tectonic stresses and prevent the development of large cross-cutting failures in the repository area. (author)

  3. Physical modeling of rock

    International Nuclear Information System (INIS)

    Cheney, J.A.

    1981-01-01

    The problems of statisfying similarity between a physical model and the prototype in rock wherein fissures and cracks place a role in physical behavior is explored. The need for models of large physical dimensions is explained but also testing of models of the same prototype over a wide range of scales is needed to ascertain the influence of lack of similitude of particular parameters between prototype and model. A large capacity centrifuge would be useful in that respect

  4. Rock disposal problems identified

    Energy Technology Data Exchange (ETDEWEB)

    Knox, R

    1978-06-01

    Mathematical models are the only way of examining the return of radioactivity from nuclear waste to the environment over long periods of time. Work in Britain has helped identify areas where more basic data is required, but initial results look very promising for final disposal of high level waste in hard rock repositories. A report by the National Radiological Protection Board of a recent study, is examined.

  5. Rock pushing and sampling under rocks on Mars

    Science.gov (United States)

    Moore, H.J.; Liebes, S.; Crouch, D.S.; Clark, L.V.

    1978-01-01

    Viking Lander 2 acquired samples on Mars from beneath two rocks, where living organisms and organic molecules would be protected from ultraviolet radiation. Selection of rocks to be moved was based on scientific and engineering considerations, including rock size, rock shape, burial depth, and location in a sample field. Rock locations and topography were established using the computerized interactive video-stereophotogrammetric system and plotted on vertical profiles and in plan view. Sampler commands were developed and tested on Earth using a full-size lander and surface mock-up. The use of power by the sampler motor correlates with rock movements, which were by plowing, skidding, and rolling. Provenance of the samples was determined by measurements and interpretation of pictures and positions of the sampler arm. Analytical results demonstrate that the samples were, in fact, from beneath the rocks. Results from the Gas Chromatograph-Mass Spectrometer of the Molecular Analysis experiment and the Gas Exchange instrument of the Biology experiment indicate that more adsorbed(?) water occurs in samples under rocks than in samples exposed to the sun. This is consistent with terrestrial arid environments, where more moisture occurs in near-surface soil un- der rocks than in surrounding soil because the net heat flow is toward the soil beneath the rock and the rock cap inhibits evaporation. Inorganic analyses show that samples of soil from under the rocks have significantly less iron than soil exposed to the sun. The scientific significance of analyses of samples under the rocks is only partly evaluated, but some facts are clear. Detectable quantities of martian organic molecules were not found in the sample from under a rock by the Molecular Analysis experiment. The Biology experiments did not find definitive evidence for Earth-like living organisms in their sample. Significant amounts of adsorbed water may be present in the martian regolith. The response of the soil

  6. The Rock Characterization Facility

    International Nuclear Information System (INIS)

    Holmes, J.

    1994-01-01

    In 1989, UK Nirex began a programme of surface-based characterization of the geology and hydrogeology of a site at Sellafield to evaluate its suitability to host a deep repository for radioactive waste. The next major stage in site characterization will be the construction and operation of a Rock Characterization Facility (RCF). It will be designed to provide rock characterization information and scope for model validation to permit firmer assessment of long-term safety. It will also provide information needed to decide the detailed location, design and orientation of a repository and to inform repository construction methods. A three-phase programme is planned for the RCF. During each phase, testwork will steadily improve our geological, hydrogeological and geotechnical understanding of the site. The first phase will involve sinking two shafts. That will be preceded by the establishment of a network of monitoring boreholes to ensure that the impact of shaft sinking can be measured. This will provide valuable data for model validation. In phase two, initial galleries will be excavated, probably at a depth of 650 m below Ordnance datum, which will host a comprehensive suite of experiments. These galleries will be extended in phase three to permit access to most of the rock volume that would host the repository. (Author)

  7. Rock in Rio: forever young

    Directory of Open Access Journals (Sweden)

    Ricardo Ferreira Freitas

    2014-12-01

    Full Text Available The purpose of this article is to discuss the role of Rock in Rio: The Musical, as herald of megafestival Rock in Rio. Driven by the success that musicals have reached in Brazil, we believe that the design of this spectacle of music, dance and staging renews the brand of the rock festival, once it adds the force of young and healthy bodies to its concept. Moreover, the musical provides Rock in Rio with some distance from the controversal trilogy of sex, drugs and rock and roll, a strong mark of past festivals around the world. Thus, the musical expands the possibilities of growth for the brand.

  8. Development of artificial soft rock

    International Nuclear Information System (INIS)

    Kishi, Kiyoshi

    1995-01-01

    When foundation base rocks are deeper than the level of installing structures or there exist weathered rocks and crushed rocks in a part of base rocks, often sound artificial base rocks are made by substituting the part with concrete. But in the construction of Kashiwazaki Kariwa Nuclear Power Station of Tokyo Electric Power Co., Inc., the foundation base rocks consist of mudstone, and the stiffness of concrete is large as compared with the surrounding base rocks. As the quality of the substituting material, the nearly same stiffness as that of the surrounding soft rocks and long term stability are suitable, and the excellent workability and economical efficiency are required, therefore, artificial soft rocks were developed. As the substituting material, the soil mortar that can obtain the physical property values in stable form, which are similar to those of Nishiyama mudstone, was selected. The mechanism of its hardening and the long term stability, and the manufacturing plant are reported. As for its application to the base rocks of Kashiwazaki Kariwa Nuclear Power Station, the verification test at the site and the application to the base rocks for No. 7 plant reactor building and other places are described. (K.I.)

  9. Hydrological characteristics of Japanese rock

    International Nuclear Information System (INIS)

    Ijiri, Yuji; Sawada, Atsushi; Akahori, Kuniaki

    1999-11-01

    It is crucial to evaluate the hydrogeological characteristics of rock in Japan in order to assess the performance of geosphere. This report summarizes the hydrogeological characteristics of various rock types obtained from broad literature surveys and the fields experiments at the Kamaishi mine in northern Japan and at the Tono mine in central Japan. It is found that the hydraulic conductivity of rock mass ranges from 10 -9 m/s to 10 -8 m/s, whereas the hydraulic conductivity of fault zone ranges from 10 -9 m/s to 10 -3 m/s. It is also found that the hydraulic conductivity tends to decrease with depth. Therefore, the hydraulic conductivity of rock mass at the depth of a repository will be smaller than above values. From the investigations at outcrops and galleries throughout the country, fractures are observed as potential pathways in all rock types. All kinds of crystalline rocks and pre-Neogene sedimentary rocks are classified as fractured media where fracture flow is dominant. Among these rocks, granitic rock is considered the archetype fractured media. On the other hand, andesite, tuff and Neogene sedimentary rocks are considered as intermediate between fractured media and porous media where flow in fractures as well as in rock matrix are significant. (author)

  10. Use of Sr and Pb isotopes in gneissic-migmatic rocks in Itacambira-Barrocao, MG, Brazil

    International Nuclear Information System (INIS)

    Siga Junior, O.; Cordani, U.G.; Basei, M.A.S.; Kawashita, K.

    1987-01-01

    This work tries to show the potential of the Rb-Sr, Pb-Pb and K-Ar methods applied to basic geological mapping. The different interpretative values of these methodologies contribute to the understanding of the tectonic processes developed in the southeastern border of the Sao Francisco Craton. The Rb-Sr and Pb-Pb isotopic data for the gneissic-migmatitic unit of this sector indicates their generation during the Archean (-2.7 Ga) and Early Proterozoic (-2.1 Ga.). The high (Sr 87 /Sr 86 ) and μ 1 values also suggest an origin through reworking of older crustal rocks. The K-Ar data (and one fission track age) allow the thermal history of this domain to be delineated and suggest a vertical tectonic in the Late Brazilian Cycle, putting side by side blocks formed in different depths. (M.V.M.)

  11. Grinding into Soft, Powdery Rock

    Science.gov (United States)

    2004-01-01

    This hole in a rock dubbed 'Clovis' is the deepest hole drilled so far in any rock on Mars. NASA's Mars Exploration Rover Spirit captured this view with its microscopic imager on martian sol 217 (Aug. 12, 2004) after drilling 8.9 millimeters (0.35 inch) into the rock with its rock abrasion tool. The view is a mosaic of four frames taken by the microscopic imager. The hole is 4.5 centimeters (1.8 inches) in diameter. Clovis is key to a developing story about environmental change on Mars, not only because it is among the softest rocks encountered so far in Gusev Crater, but also because it contains mineral alterations that extend relatively deep beneath its surface. In fact, as evidenced by its fairly crumbly texture, it is possibly the most highly altered volcanic rock ever studied on Mars. Scientific analysis shows that the rock contains higher levels of the elements sulfur, chlorine, and bromine than are normally encountered in basaltic rocks, such as a rock dubbed 'Humphrey' that Spirit encountered two months after arriving on Mars. Humphrey showed elevated levels of sulfur, chlorine, and bromine only in the outermost 2 millimeters (less than 0.1 inch) of its surface. Clovis shows elevated levels of the same elements along with the associated softness of the rock within a borehole that is 4 times as deep. Scientists hope to compare Clovis to other, less-altered rocks in the vicinity to assess what sort of water-based processes altered the rock. Hypotheses include transport of sulfur, chlorine, and bromine in water vapor in volcanic gases; hydrothermal circulation (flow of volcanically heated water through rock); or saturation in a briny soup containing the same elements. In this image, very fine-grained material from the rock has clumped together by electrostatic attraction and fallen into the borehole. NASA/JPL/Cornell/USGS

  12. Hot spring microbial community composition, morphology, and carbon fixation: implications for interpreting the ancient rock record

    Science.gov (United States)

    Schuler, Caleb G.; Havig, Jeff R.; Hamilton, Trinity L.

    2017-11-01

    Microbial communities in hydrothermal systems exist in a range of macroscopic morphologies including stromatolites, mats, and filaments. The architects of these structures are typically autotrophic, serving as primary producers. Structures attributed to microbial life have been documented in the rock record dating back to the Archean including recent reports of microbially-related structures in terrestrial hot springs that date back as far as 3.5 Ga. Microbial structures exhibit a range of complexity from filaments to more complex mats and stromatolites and the complexity impacts preservation potential. As a result, interpretation of these structures in the rock record relies on isotopic signatures in combination with overall morphology and paleoenvironmental setting. However, the relationships between morphology, microbial community composition, and primary productivity remain poorly constrained. To begin to address this gap, we examined community composition and carbon fixation in filaments, mats, and stromatolites from the Greater Obsidian Pool Area (GOPA) of the Mud Volcano Area, Yellowstone National Park, WY. We targeted morphologies dominated by bacterial phototrophs located in close proximity within the same pool which are exposed to similar geochemistry as well as bacterial mat, algal filament and chemotrophic filaments from nearby springs. Our results indicate i) natural abundance δ13C values of biomass from these features (-11.0 to -24.3 ‰) are similar to those found in the rock record; ii) carbon uptake rates of photoautotrophic communities is greater than chemoautotrophic; iii) oxygenic photosynthesis, anoxygenic photosynthesis, and chemoautotrophy often contribute to carbon fixation within the same morphology; and iv) increasing phototrophic biofilm complexity corresponds to a significant decrease in rates of carbon fixation—filaments had the highest uptake rates whereas carbon fixation by stromatolites was significantly lower. Our data highlight

  13. Hot Spring Microbial Community Composition, Morphology, and Carbon Fixation: Implications for Interpreting the Ancient Rock Record

    Directory of Open Access Journals (Sweden)

    Caleb G. Schuler

    2017-11-01

    Full Text Available Microbial communities in hydrothermal systems exist in a range of macroscopic morphologies including stromatolites, mats, and filaments. The architects of these structures are typically autotrophic, serving as primary producers. Structures attributed to microbial life have been documented in the rock record dating back to the Archean including recent reports of microbially-related structures in terrestrial hot springs that date back as far as 3.5 Ga. Microbial structures exhibit a range of complexity from filaments to more complex mats and stromatolites and the complexity impacts preservation potential. As a result, interpretation of these structures in the rock record relies on isotopic signatures in combination with overall morphology and paleoenvironmental setting. However, the relationships between morphology, microbial community composition, and primary productivity remain poorly constrained. To begin to address this gap, we examined community composition and carbon fixation in filaments, mats, and stromatolites from the Greater Obsidian Pool Area (GOPA of the Mud Volcano Area, Yellowstone National Park, WY. We targeted morphologies dominated by bacterial phototrophs located in close proximity within the same pool which are exposed to similar geochemistry as well as bacterial mat, algal filament and chemotrophic filaments from nearby springs. Our results indicate (i natural abundance δ13C values of biomass from these features (−11.0 to −24.3‰ are similar to those found in the rock record; (ii carbon uptake rates of photoautotrophic communities is greater than chemoautotrophic; (iii oxygenic photosynthesis, anoxygenic photosynthesis, and chemoautotrophy often contribute to carbon fixation within the same morphology; and (iv increasing phototrophic biofilm complexity corresponds to a significant decrease in rates of carbon fixation—filaments had the highest uptake rates whereas carbon fixation by stromatolites was significantly lower

  14. On the nature and origin of garnet in highly-refractory Archean lithosphere: implications for continent stabilisation

    Science.gov (United States)

    Gibson, Sally

    2014-05-01

    The nature and timescales of garnet formation in the Earth's subcontinental lithospheric mantle (SCLM) are important to our understanding of how this rigid outer shell has evolved and stabilised since the Archean. Nevertheless, the widespread occurrence of pyrope garnet in the sub-cratonic mantle remains one of the 'holy grails' of mantle petrology. The paradox is that garnet often occurs in mantle lithologies (dunites and harzburgites) which represent residues of major melting events (up to 40 %) whereas experimental studies on fertile peridotite suggest this phase should be exhausted by years. The garnets display systematic trends from ultra-depleted to enriched compositions that have not been recognised in peridotite suites from elsewhere (Gibson et al., 2013). Certain harzburgite members of the xenolith suite contain the first reported occurrence of pyrope garnets with rare-earth element (REE) patterns similar to hypothetical garnets proposed by Stachel et al. (2004) to have formed in the Earth's SCLM during the Archean, prior to metasomatism. These rare ultra-depleted low-Cr garnets occur in low temperature (~1050 oC) xenoliths derived from depths of ~120 km and coexist in chemical and textural equilibrium with highly-refractory olivine (Fo95.4) and orthopyroxene (Mg#=96.4). These phases are all more magnesian than generally encountered in global samples of depleted mantle, i.e. harzburgites and diamond inclusion suites. The Tanzanian ultra-depleted garnets form interconnecting networks ('necklaces') around grains of orthopyroxene, which is of key importance to their origin. This close spatial relationship of garnet and orthopyroxene together with the major, trace and REE contents of the ultra-depleted garnets, are consistent with an origin by isochemical exsolution. The significance of ultra-depleted low-Cr garnets has not previously been recognised in global suites of mantle xenoliths or diamond inclusions: they appear to have been overlooked, primarily

  15. Geotectonic structural interpretation of the basement complex at the eastern border of the Espinhaco ridge, in Guanhaes and Gouveia region, based on an integration of their U/Pb and K/Ar geochronology united

    International Nuclear Information System (INIS)

    Teixeira, W.; Salvador, E.D.; Siga Junior, O.; Sato, K.; Dossin, I.A.; Dossin, T.M.

    1990-01-01

    The basement complex at the eastern border of the Espinhaco ridge is composed of predominantly gneissic rocks which were subjected to migmatization and granitization. Overall the area shows complex tectonic evolution with recurrence of tectonomagmatic and metamorphic events as supported by geological, geochronological and structural studies. The Rb/Sr geochronology carried out on the basement rocks and metavolcanics from the Espinhaco interpreted together with the published U-Pb, Rb-Sr and K-Ar data defines the following scenario for the Precambrian crustal evolution. 1. Primary origin of a sialic crust at 2.97-2.84 Ga. ago as supported by U-Pb zircon ages. 2. Crustal reworking of the Archean crust and subordinate juvenile accretion from upper mantle during the 2.2-2.OGa. period, as suggested by the isochrons. 3. Recurrence of Middle Proterozoic events over the basement rocks (gneisses and charnockites) and metavolcanics of the Espinhaco as showed by isochrons. 4. Development of Late Proterozoic migmatization over the basement rocks (0.75 Ga., R.I.= 0.787) is association with Collisional tectonics and resetting of K-Ar mineral systems. (author)

  16. Flow banding in basaltic pillow lavas from the Early Archean Hooggenoeg Formation, Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Robins, Brian; Sandstå, Nils Rune; Furnes, Harald; de Wit, Maarten

    2010-07-01

    Well-preserved pillow lavas in the uppermost part of the Early Archean volcanic sequence of the Hooggenoeg Formation in the Barberton Greenstone Belt exhibit pronounced flow banding. The banding is defined by mm to several cm thick alternations of pale green and a dark green, conspicuously variolitic variety of aphyric metabasalt. Concentrations of relatively immobile TiO2, Al2O3 and Cr in both varieties of lava are basaltic. Compositional differences between bands and variations in the lavas in general have been modified by alteration, but indicate mingling of two different basalts, one richer in TiO2, Al2O3, MgO, FeOt and probably Ni and Cr than the other, as the cause of the banding. The occurrence in certain pillows of blebs of dark metabasalt enclosed in pale green metabasalt, as well as cores of faintly banded or massive dark metabasalt, suggest that breakup into drops and slugs in the feeder channel to the lava flow initiated mingling. The inhomogeneous mixture was subsequently stretched and folded together during laminar shear flow through tubular pillows, while diffusion between bands led to partial homogenisation. The most common internal pattern defined by the flow banding in pillows is concentric. In some pillows the banding defines curious mushroom-like structures, commonly cored by dark, variolitic metabasalt, which we interpret as the result of secondary lateral flow due to counter-rotating, transverse (Dean) vortices induced by the axial flow of lava towards the flow front through bends, generally downward, in the tubular pillows. Other pillows exhibit weakly-banded or massive, dark, variolitic cores that are continuous with wedge-shaped apophyses and veins that intrude the flow banded carapace. These cores represent the flow of hotter and less viscous slugs of the dark lava type into cooled and stiffened pillows.

  17. Rock mechanics for hard rock nuclear waste repositories

    International Nuclear Information System (INIS)

    Heuze, F.E.

    1981-09-01

    The mined geologic burial of high level nuclear waste is now the favored option for disposal. The US National Waste Terminal Storage Program designed to achieve this disposal includes an extensive rock mechanics component related to the design of the wastes repositories. The plan currently considers five candidate rock types. This paper deals with the three hard rocks among them: basalt, granite, and tuff. Their behavior is governed by geological discontinuities. Salt and shale, which exhibit behavior closer to that of a continuum, are not considered here. This paper discusses both the generic rock mechanics R and D, which are required for repository design, as well as examples of projects related to hard rock waste storage. The examples include programs in basalt (Hanford/Washington), in granitic rocks (Climax/Nevada Test Site, Idaho Springs/Colorado, Pinawa/Canada, Oracle/Arizona, and Stripa/Sweden), and in tuff

  18. Rock stress investigations

    International Nuclear Information System (INIS)

    Pahl, A.; Heusermann, St.; Braeuer, V.; Gloeggler, W.

    1989-04-01

    On the research project 'Rock Stress Mesurements' the BGR has developed and tested several methods for use in boreholes at a depth of 200 m. Indirect stress measurements using overcoring methods with BGR-probes and CSIR-triaxial cells as well as direct stress measurements using the hydraulic-fracturing method were made. To determine in-situ rock deformation behavior borehole deformation tests, using a BGR-dilatometer, were performed. Two types of the BGR-probe were applied: a four-component-probe to determine horizontal stresses and a five-component-probe to determine a quasi three-dimensional stress field. The first time a computer for data processing was installed in the borehole together with the BGR-probe. Laboratory tests on low cylinders were made to study the stress-deformation behavior. To validate and to interprete the measurement results some test methods were modelled using the finite-element method. The dilatometer-tests yielded high values of Young's modulus, whereas laboratory tests showed lower values with a distinct deformation anisotropy. Stress measurements with the BGR-probe yielded horizontal stresses being higher than the theoretical overburden pressure. These results are comparable to the results of the hydraulic fracturing tests, whereas stresses obtained with CSIR-triaxial cells are lower. The detailed geological mapping of the borehole indicated relationships between stress and geology. With regard to borehole depth different zones of rock structure joint frequency, joint orientation, and orientation of microfissures as well as stress magnitude, stress direction, and degree of deformation anisotropy could be distinguished. (author) 4 tabs., 76 figs., 31 refs

  19. Petrogenesis of siliceous high-Mg series rocks as exemplified by the Early Paleoproterozoic mafic volcanic rocks of the Eastern Baltic Shield: enriched mantle versus crustal contamination

    Science.gov (United States)

    Bogina, Maria; Zlobin, Valeriy; Sharkov, Evgenii; Chistyakov, Alexeii

    2015-04-01

    The Early Paleoproterozoic stage in the Earth's evolution was marked by the initiation of global rift systems, the tectonic nature of which was determined by plume geodynamics. These processes caused the voluminous emplacement of mantle melts with the formation of dike swarms, mafic-ultramafic layered intrusions, and volcanic rocks. All these rocks are usually considered as derivatives of SHMS (siliceous high-magnesian series). Within the Eastern Baltic Shield, the SHMS volcanic rocks are localized in the domains with different crustal history: in the Vodlozero block of the Karelian craton with the oldest (Middle Archean) crust, in the Central Block of the same craton with the Neoarchean crust, and in the Kola Craton with a heterogeneous crust. At the same time, these rocks are characterized by sufficiently close geochemical characteristics: high REE fractionation ((La/Yb)N = 4.9-11.7, (La/Sm)N=2.3-3.6, (Gd/Yb)N =1.66-2.74)), LILE enrichment, negative Nb anomaly, low to moderate Ti content, and sufficiently narrow variations in Nd isotope composition from -2.0 to -0.4 epsilon units. The tectonomagmatic interpretation of these rocks was ambiguous, because such characteristics may be produced by both crustal contamination of depleted mantle melts, and by generation from a mantle source metasomatized during previous subduction event. Similar REE patterns and overlapping Nd isotope compositions indicate that the studied basaltic rocks were formed from similar sources. If crustal contamination en route to the surface would play a significant role in the formation of the studied basalts, then almost equal amounts of contaminant of similar composition are required to produce the mafic rocks with similar geochemical signatures and close Nd isotopic compositions, which is hardly possible for the rocks spaced far apart in a heterogeneous crust. This conclusion is consistent with analysis of some relations between incompatible elements and their ratios. In particular, the

  20. A smart rock

    Science.gov (United States)

    Pressel, Phil

    2014-12-01

    This project was to design and build a protective weapon for a group of associations that believed in aliens and UFO's. They collected enough contributions from societies and individuals to be able to sponsor and totally fund the design, fabrication and testing of this equipment. The location of this facility is classified. It also eventually was redesigned by the Quartus Engineering Company for use at a major amusement park as a "shoot at targets facility." The challenge of this project was to design a "smart rock," namely an infrared bullet (the size of a gallon can of paint) that could be shot from the ground to intercept a UFO or any incoming suspicious item heading towards the earth. Some of the challenges to design this weapon were to feed cryogenic helium at 5 degrees Kelvin from an inair environment through a unique rotary coupling and air-vacuum seal while spinning the bullet at 1500 rpm and maintain its dynamic stability (wobble) about its spin axis to less than 10 micro-radians (2 arc seconds) while it operated in a vacuum. Precision optics monitored the dynamic motion of the "smart rock."

  1. Rock critics as 'Mouldy Modernists'

    Directory of Open Access Journals (Sweden)

    Becky Shepherd

    2011-08-01

    Full Text Available Contemporary rock criticism appears to be firmly tied to the past. The specialist music press valorise rock music of the 1960s and 1970s, and new emerging artists are championed for their ‘retro’ sounding music by journalists who compare the sound of these new artists with those included in the established ‘canon’ of rock music. This article examines the narrative tropes of authenticity and nostalgia that frame the retrospective focus of this contemporary rock writing, and most significantly, the maintenance of the rock canon within contemporary popular culture. The article concludes by suggesting that while contemporary rock criticism is predominately characterised by nostalgia, this nostalgia is not simply a passive romanticism of the past. Rather, this nostalgia fuels a process of active recontextualisation within contemporary popular culture.

  2. Rock.XML - Towards a library of rock physics models

    Science.gov (United States)

    Jensen, Erling Hugo; Hauge, Ragnar; Ulvmoen, Marit; Johansen, Tor Arne; Drottning, Åsmund

    2016-08-01

    Rock physics modelling provides tools for correlating physical properties of rocks and their constituents to the geophysical observations we measure on a larger scale. Many different theoretical and empirical models exist, to cover the range of different types of rocks. However, upon reviewing these, we see that they are all built around a few main concepts. Based on this observation, we propose a format for digitally storing the specifications for rock physics models which we have named Rock.XML. It does not only contain data about the various constituents, but also the theories and how they are used to combine these building blocks to make a representative model for a particular rock. The format is based on the Extensible Markup Language XML, making it flexible enough to handle complex models as well as scalable towards extending it with new theories and models. This technology has great advantages as far as documenting and exchanging models in an unambiguous way between people and between software. Rock.XML can become a platform for creating a library of rock physics models; making them more accessible to everyone.

  3. Rocks under pressure

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-05-01

    Physicists have used nuclear magnetic resonance to investigate the destructive effects of the crystallization of salt. Salt-weathering is one of the main causes of rock disintegration in nature, particularly in deserts, polar regions and along coastlines. However, it is also a very widespread cause of damage to man-made constructions. Bridges, for example, are attacked by de-icing salts, and cities such as Bahrain, Abu Dhabi and Adelaide are affected by rising damp from high ground-water levels. Indeed, many examples of cultural heritage, including the Islamic sites of Bokhara and Petra in Jordan and the Sphinx in Egypt, may ultimately be destroyed due to the effects of salt-weathering. Now Lourens Rijniers and colleagues at Eindhoven University in the Netherlands have developed a way to observe the solubility of various salts inside porous materials directly (Phys. Rev. Lett. 94 075503). (U.K.)

  4. Rock the Globe

    CERN Multimedia

    Laëtitia Pedroso

    2010-01-01

    Created in 2005, the Swiss rock band "Wind of Change" is now candidate for the Eurovision Song Contest 2011 with a new song " Night & Light " with the music video filmed at CERN.   With over 20 gigs under their belt and two albums already released, the five members of the band (Alex Büchi, vocals; Arthur Spierer, drums; David Gantner, bass; Romain Mage and Yannick Gaudy, guitar) continue to excite audiences. For their latest composition "Night & Light", the group filmed their music video in the Globe of Science and Innovation. Winning the Eurovision contest would be a springboard in their artistic career for these young musicians. The selection results will be available December 11, 2010.      

  5. Electrochemistry of lunar rocks

    Science.gov (United States)

    Lindstrom, D. J.; Haskin, L. A.

    1979-01-01

    Electrolysis of silicate melts has been shown to be an effective means of producing metals from common silicate materials. No fluxing agents need be added to the melts. From solution in melts of diopside (CaMgSi2O6) composition, the elements Si, Ti, Ni, and Fe have been reduced to their metallic states. Platinum is a satisfactory anode material, but other cathode materials are needed. Electrolysis of compositional analogs of lunar rocks initially produces iron metal at the cathode and oxygen gas at the anode. Utilizing mainly heat and electricity which are readily available from sunlight, direct electrolysis is capable of producing useful metals from common feedstocks without the need for expendable chemicals. This simple process and the products obtained from it deserve further study for use in materials processing in space.

  6. Preliminary study of the uranium favorability of granitic and contact-metamorphic rocks of the Owens Valley area, Inyo and Mono Counties, California, and Esmeralda and Mineral Counties, Nevada

    International Nuclear Information System (INIS)

    Cupp, G.M.; Mitchell, T.P.

    1978-01-01

    Granitic and contact-metamorphic rocks of the Owens Valley area were sampled to determine their favorability for uranium. Uranium deposits associated with these rocks were examined to determine the mode of occurrence. Metamorphic rocks near contacts with intrusive rocks include skarns, schists, quartzites, metaconglomerates, hornfels, gneisses, and metavolcanics. The grade of contact metamorphism ranges from slight to intense, depending upon the distance from the intrusive contact. The average U 3 O 8 content of the metamorphic rock samples is 3 ppM. Metamorphic rock samples in a roof pendant at the Claw prospect contain as much as 3 percent U 3 O 8 . Skarn samples from the Birch Creek pluton contain as much as 114 ppM U 3 O 8 ; those from the Santa Rita Flat pluton contain as much as 23 ppM U 3 O 8 . Most of the intrusive rocks are granite, quartz monzonite, or monzonite. Granodiorite and diorite are less common, and gabbro is rare. The average U 3 O 8 content of the crystalline rock samples is 4 ppM. Samples from a quartz-monzonite pluton east of Lone Pine, California, and quartz monzonite in the Santa Rosa Hills had maximum contents of 28 and 13 ppM U 3 O 8 , respectively. Areas of contact metamorphism and metasomatism, such as those at the Claw prospect and Birch Creek pluton, are probably the most favorable sites for uranium deposits. There are many miles of granitic and contact-metamorphic zones in which undiscovered uranium deposits may exist. Although the overall uranium content of granitic rocks appears to be low, the pluton east of Lone Pine and the Hunter Mountain pluton in the area of the Santa Rosa Hills have sufficient uranium to have acted as uranium and detrital source rocks for uranium deposits that may now be buried in Tertiary sediments in the basins around the plutons. The Claw deposit is the only known uranium deposit of a size and grade to be of possible commercial interest

  7. Rock Art in Kurdistan Iran

    Directory of Open Access Journals (Sweden)

    Jamal Lahafian

    2013-12-01

    Full Text Available Kurdistan, with great potential and prehistoric resources, has numerous petroglyphs in different areas of the province. During the last 14 years of extensive field study, more than 30 sites of rock art have been identified and introduced by the author. In this article, we summarize these rock art areas in Iranian Kurdistan.

  8. Rockin' around the Rock Cycle

    Science.gov (United States)

    Frack, Susan; Blanchard, Scott Alan

    2005-01-01

    In this activity students will simulate how sedimentary rocks can be changed into metamorphic rocks by intense pressure. The materials needed are two small pieces of white bread, one piece of wheat bread, and one piece of a dark bread (such as pumpernickel or dark rye) per student, two pieces of waxed paper, scissors, a ruler, and heavy books.…

  9. 'Mister Badger' Pushing Mars Rock

    Science.gov (United States)

    1976-01-01

    Viking's soil sampler collector arm successfully pushed a rock on the surface of Mars during the afternoon of Friday, October 8. The irregular-shaped rock was pushed several inches by the Lander's collector arm, which displaced the rock to the left of its original position, leaving it cocked slightly upward. Photographs and other information verified the successful rock push. Photo at left shows the soil sampler's collector head pushing against the rock, named 'Mister Badger' by flight controllers. Photo at right shows the displaced rock and the depression whence it came. Part of the soil displacement was caused by the collector s backhoe. A soil sample will be taken from the site Monday night, October 11. It will then be delivered to Viking s organic chemistry instrument for a series of analyses during the next few weeks. The sample is being sought from beneath a rock because scientists believe that, if there are life forms on Mars, they may seek rocks as shelter from the Sun s intense ultraviolet radiation.

  10. Rock suitability classification RSC 2012

    Energy Technology Data Exchange (ETDEWEB)

    McEwen, T. (ed.) [McEwen Consulting, Leicester (United Kingdom); Kapyaho, A. [Geological Survey of Finland, Espoo (Finland); Hella, P. [Saanio and Riekkola, Helsinki (Finland); Aro, S.; Kosunen, P.; Mattila, J.; Pere, T.

    2012-12-15

    This report presents Posiva's Rock Suitability Classification (RSC) system, developed for locating suitable rock volumes for repository design and construction. The RSC system comprises both the revised rock suitability criteria and the procedure for the suitability classification during the construction of the repository. The aim of the classification is to avoid such features of the host rock that may be detrimental to the favourable conditions within the repository, either initially or in the long term. This report also discusses the implications of applying the RSC system for the fulfilment of the regulatory requirements concerning the host rock as a natural barrier and the site's overall suitability for hosting a final repository of spent nuclear fuel.

  11. Rock suitability classification RSC 2012

    International Nuclear Information System (INIS)

    McEwen, T.; Kapyaho, A.; Hella, P.; Aro, S.; Kosunen, P.; Mattila, J.; Pere, T.

    2012-12-01

    This report presents Posiva's Rock Suitability Classification (RSC) system, developed for locating suitable rock volumes for repository design and construction. The RSC system comprises both the revised rock suitability criteria and the procedure for the suitability classification during the construction of the repository. The aim of the classification is to avoid such features of the host rock that may be detrimental to the favourable conditions within the repository, either initially or in the long term. This report also discusses the implications of applying the RSC system for the fulfilment of the regulatory requirements concerning the host rock as a natural barrier and the site's overall suitability for hosting a final repository of spent nuclear fuel

  12. Rock strength under explosive loading

    International Nuclear Information System (INIS)

    Rimer, N.; Proffer, W.

    1993-01-01

    This presentation emphasizes the importance of a detailed description of the nonlinear deviatoric (strength) response of the surrounding rock in the numerical simulation of underground nuclear explosion phenomenology to the late times needed for test ban monitoring applications. We will show how numerical simulations which match ground motion measurements in volcanic tuffs and in granite use the strength values obtained from laboratory measurements on small core samples of these rocks but also require much lower strength values after the ground motion has interacted with the rock. The underlying physical mechanisms for the implied strength reduction are not yet well understood, and in fact may depend on the particular rock type. However, constitutive models for shock damage and/or effective stress have been used successfully at S-Cubed in both the Geophysics Program (primarily for DARPA) and the Containment Support Program (for DNA) to simulate late time ground motions measured at NTS in many different rock types

  13. ROCK inhibitors in ocular disease

    Directory of Open Access Journals (Sweden)

    Eva Halasz

    2016-12-01

    Full Text Available Rho kinases (ROCKs have a crucial role in actin-cytoskeletal reorganization and thus are involved in broad aspects of cell motility, from smooth muscle contraction to neurite outgrowth. The first marketed ROCK inhibitor, called fasudil, has been used safely for treatment of cerebral vasospasm since 1995 in Japan. During the succeeding decades ROCK inhibitors have been applied in many pathological conditions from central nervous system disorders to cardiovascular disease as potential therapeutic agents or experimental tools to help understand the underlying (pathomechanisms. In 2014, a fasudil derivate named ripasudil was accepted for clinical use in glaucoma and ocular hypertension. Since ROCK kinases are widely expressed in ocular tissues, they have been implicated in the pathology of many ocular conditions such as corneal dysfunction, glaucoma, cataract, diabetic retinopathy, age-related macular degeneration, and retinal detachment. This paper aims to provide an overview of the most recent status/application of ROCK inhibitors in the field of eye disease.

  14. The age of the rocks and the metamorphic episodes from the Southeastern of Sao Paulo state

    International Nuclear Information System (INIS)

    Tassinari, C.C.G.; Kawashita, K.; Schmuss, R. van; Taylor, P.N.

    1988-01-01

    Rb-Sr, Pb-Pb and U-Pb geochronologic studies carried out on precambrian rocks from the southeastern Sao Paulo state suggest a Complex geologic evolution during the Archean and Proterozoic times. This region is divided in five differents allochthonous terranes named Itapira-Amparo, Piracaiba-Jundiai, Sao Roque, Embu and Costeiro, separated by thrust and strike-slip faults. The Itapira-Amparo domain has a original history dating back to 3.4 Ga. and since 2.6 to 2.5 Ga. and 2.2 to 1.9 Ga. metamorphic rockformation episode occurred involving both mantle-derived magmas and recycled material. Supracrustal sequences developed around 1.4 Ga. The domain was locally reworked in 0.8 - 0.65 Ga. In the Piracaia-Jundiai the main rock-formation event occurred at 1.4 Ga., but this domian was affected by strong granization and migmatization episodes during the period 1.1 - 0.6 Ga. The third terrain is characterized by the Sao Roque metavolcanossedimentary sequence developed during the time period 1.8 - 0.7 Ga., and comprising two metamorphic superimposed events (1.4 and 0.8 - 0.7 Ga.). the post-tectonics granites ranging in ages from 0.7 to 0.55 Ga. Within the Embu terrain ages of 2.5, 1.4 and 0,75 Ga. were obtained for the metamorphic terrain, with post-tectonic activities around 650 Ma. In the Costeiro domain all the metamorphic rocks developed in late-Proterozoic time, with syntectonic phase around 650 Ma [pt

  15. Partial melting of metavolcanics in amphibolite facies regional ...

    Indian Academy of Sciences (India)

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

    Department of Geology and Geography, University of Massachusetts,. Amherst), pp 275. Hollocher K 1991 Prograde amphibole dehydration reac- tions during high grade regional metamorphism, Central. Massachusetts, U.S.A.; Am. Mineral.

  16. Coupled Nd-142, Nd-143 and Hf-176 Isotopic Data from 3.6-3.9 Ga Rocks: New Constraints on the Timing of Early Terrestrial Chemical Reservoirs

    Science.gov (United States)

    Bennett, Vickie C.; Brandon, alan D.; Hiess, Joe; Nutman, Allen P.

    2007-01-01

    Increasingly precise data from a range of isotopic decay schemes, including now extinct parent isotopes, from samples of the Earth, Mars, Moon and meteorites are rapidly revising our views of early planetary differentiation. Recognising Nd-142 isotopic variations in terrestrial rocks (which can only arise from events occurring during the lifetime of now extinct Sm-146 [t(sub 1/2)=103 myr]) has been an on-going quest starting with Harper and Jacobsen. The significance of Nd-142 variations is that they unequivocally reflect early silicate differentiation processes operating in the first 500 myr of Earth history, the key time period between accretion and the beginning of the rock record. The recent establishment of the existence of Nd-142 variations in ancient Earth materials has opened a new range of questions including, how widespread is the evidence of early differentiation, how do Nd-142 compositions vary with time, rock type and geographic setting, and, combined with other types of isotopic and geochemical data, what can Nd-142 isotopic variations reveal about the timing and mechanisms of early terrestrial differentiation? To explore these questions we are determining high precision Nd-142, Nd-143 and Hf-176 isotopic compositions from the oldest well preserved (3.63- 3.87 Ga), rock suites from the extensive early Archean terranes of southwest Greenland and western Australia.

  17. They will rock you!

    CERN Multimedia

    Anaïs Schaeffer

    2013-01-01

    On 30 September, CERN will be the venue for one of the most prestigious events of the year: the concert for the Bosons&More event, the Organization’s celebration of the remarkable performance of the LHC and all its technical systems, as well as the recent fundamental discoveries. Topping the bill will be the Orchestre de la Suisse Romande, the CERN Choir, the Zürcher Sing-Akademie and the Alan Parsons Live Project rock group, who have joined forces to create an unforgettable evening’s entertainment.   The Orchestre de la Suisse Romande, directed by Maestro Neeme Järvi, artistic and musical director of the OSR. (Image: Grégory Maillot). >>> From the Orchestre de la Suisse Romande… Henk Swinnen, General Manager of the Orchestre de la Suisse Romande (OSR), answers some questions for the CERN Bulletin, just a few days before the event. How did this project come about? When CERN invited us to take part in the B...

  18. Rock salt constitutive modeling

    International Nuclear Information System (INIS)

    Nickell, R.E.

    1980-01-01

    The Serata model is the best operational model available today because it incorporates: (1) a yield function to demarcate between viscoelastic and viscoplastic behavior of rock salt; (2) a pressure and temperature dependence for yield stresses; and (3) a standard linear solid, which can be readily extended into the non-linear regime, to represent creep behavior. Its only deficiencies appear to be the lack of secondary creep behavior (a free dashpot) and some unsettling arbitrariness about the Poisson's ratio (ν → 0.5) argument for viscoplasticity. The Sandia/WIPP model will have good primary and secondary creep capability, but lacks the viscoplastic behavior. In some cases, estimated inelastic strains may be underpredicted. If a creep acceleration mechanism associated with brine inclusions is observed, this model may require extensive revision. Most of the other models available (SAI, RE-SPEC, etc.) are only useful for short-term calculations, because they employ temporal power law (t/sup n/) primary creep representations. These models are unsatisfactory because they cannot represent dual mechanisms with differing characteristic times. An approach based upon combined creep and plasticity is recommended in order to remove the remaining deficiency in the Serata model. DOE/Sandia/WIPP should be encouraged to move aggressively in this regard

  19. Research into basic rocks types

    International Nuclear Information System (INIS)

    1993-06-01

    Teollisuuden Voima Oy (TVO) has carried out research into basic rock types in Finland. The research programme has been implemented in parallel with the preliminary site investigations for radioactive waste disposal in 1991-1993. The program contained two main objectives: firstly, to study the properties of the basic rock types and compare those with the other rock types under the investigation; secondly, to carry out an inventory of rock formations consisting of basic rock types and suitable in question for final disposal. A study of environmental factors important to know regarding the final disposal was made of formations identified. In total 159 formations exceeding the size of 4 km 2 were identified in the inventory. Of these formations 97 were intrusive igneous rock types and 62 originally extrusive volcanic rock types. Deposits consisting of ore minerals, industrial minerals or building stones related to these formations were studied. Environmental factors like natural resources, protected areas or potential for restrictions in land use were also studied

  20. Modeling the Rock Glacier Cycle

    Science.gov (United States)

    Anderson, R. S.; Anderson, L. S.

    2016-12-01

    Rock glaciers are common in many mountain ranges in which the ELA lies above the peaks. They represent some of the most identifiable components of today's cryosphere in these settings. Their oversteepened snouts pose often-overlooked hazards to travel in alpine terrain. Rock glaciers are supported by avalanches and by rockfall from steep headwalls. The winter's avalanche cone must be sufficiently thick not to melt entirely in the summer. The spatial distribution of rock glaciers reflects this dependence on avalanche sources; they are most common on lee sides of ridges where wind-blown snow augments the avalanche source. In the absence of rockfall, this would support a short, cirque glacier. Depending on the relationship between rockfall and avalanche patterns, "talus-derived" and "glacier-derived" rock glaciers are possible. Talus-derived: If the spatial distribution of rock delivery is similar to the avalanche pattern, the rock-ice mixture will travel an englacial path that is downward through the short accumulation zone before turning upward in the ablation zone. Advected debris is then delivered to the base of a growing surface debris layer that reduces the ice melt rate. The physics is identical to the debris-covered glacier case. Glacier-derived: If on the other hand rockfall from the headwall rolls beyond the avalanche cone, it is added directly to the ablation zone of the glacier. The avalanche accumulation zone then supports a pure ice core to the rock glacier. We have developed numerical models designed to capture the full range of glacier to debris-covered glacier to rock glacier behavior. The hundreds of meter lengths, tens of meters thicknesses, and meter per year speeds of rock glaciers are well described by the models. The model can capture both "talus-derived" and "glacier-derived" rock glaciers. We explore the dependence of glacier behavior on climate histories. As climate warms, a pure ice debris-covered glacier can transform to a much shorter rock

  1. Multiverso: Rock'n'Astronomy

    Science.gov (United States)

    Caballero, J. A.

    2012-05-01

    In the last few years, there have been several projects involving astronomy and classical music. But have a rock band ever appeared at a science conference or an astronomer at a rock concert? We present a project, Multiverso, in which we mix rock and astronomy, together with poetry and video art (Caballero, 2010). The project started in late 2009 and has already reached tens of thousands people in Spain through the release of an album, several concert-talks, television, radio, newspapers and the internet.

  2. Fault rocks and uranium mineralization

    International Nuclear Information System (INIS)

    Tong Hangshou.

    1991-01-01

    The types of fault rocks, microstructural characteristics of fault tectonite and their relationship with uranium mineralization in the uranium-productive granite area are discussed. According to the synthetic analysis on nature of stress, extent of crack and microstructural characteristics of fault rocks, they can be classified into five groups and sixteen subgroups. The author especially emphasizes the control of cataclasite group and fault breccia group over uranium mineralization in the uranium-productive granite area. It is considered that more effective study should be made on the macrostructure and microstructure of fault rocks. It is of an important practical significance in uranium exploration

  3. Test procedures for salt rock

    International Nuclear Information System (INIS)

    Dusseault, M.B.

    1985-01-01

    Potash mining, salt mining, design of solution caverns in salt rocks, disposal of waste in salt repositories, and the use of granular halite backfill in underground salt rock mines are all mining activities which are practised or contemplated for the near future. Whatever the purpose, the need for high quality design parameters is evident. The authors have been testing salt rocks in the laboratory in a number of configurations for some time. Great care has been given to the quality of sample preparation and test methodology. This paper describes the methods, presents the elements of equipment design, and shows some typical results

  4. Fluid and rock interaction in permeable volcanic rock

    International Nuclear Information System (INIS)

    Lindley, J.I.

    1985-01-01

    Four types of interrelated changes -geochemical, mineralogic, isotopic, and physical - occur in Oligocene volcanic units of the Mogollon-Datil volcanic field, New Mexico. These changes resulted from the operation of a geothermal system that, through fluid-rock interaction, affected 5 rhyolite ash-flow tuffs and an intercalated basaltic andesite lava flow causing a potassium metasomatism type of alteration. (1) Previous studies have shown enrichment of rocks in K 2 O as much as 130% of their original values at the expense of Na 2 O and CaO with an accompanying increase in Rb and decreases in MgO and Sr. (2) X-ray diffraction results of this study show that phenocrystic plagioclase and groundmass feldspar have been replaced with pure potassium feldspar and quartz in altered rock. Phenocrystic potassium feldspar, biotite, and quartz are unaffected. Pyroxene in basaltic andesite is replaced by iron oxide. (3) delta 18 O increases for rhyolitic units from values of 8-10 permil, typical of unaltered rock, to 13-15 permil, typical of altered rock. Basaltic andesite, however, shows opposite behavior with a delta 18 of 9 permil in unaltered rock and 6 permit in altered. (4) Alteration results in a density decrease. SEM revealed that replacement of plagioclase by fine-grained quartz and potassium feldspar is not a volume for volume replacement. Secondary porosity is created in the volcanics by the chaotic arrangement of secondary crystals

  5. Recycled Archean sulfur in the mantle wedge of the Mariana Forearc and microbial sulfate reduction within an extremely alkaline serpentine seamount

    Science.gov (United States)

    Aoyama, Shinnosuke; Nishizawa, Manabu; Miyazaki, Junichi; Shibuya, Takazo; Ueno, Yuichiro; Takai, Ken

    2018-06-01

    The identification of microbial activity under extreme conditions is important to define potential boundaries of the habitable and uninhabitable zones of terrestrial and extraterrestrial living forms. The subseafloor regimes of serpentinite seamounts in the Mariana Forearc are among the most extreme environments for life on earth owing to the widespread presence of highly alkaline fluids with pH values greater than 12. The potential activity of sulfate-reducing microorganisms has been suggested within the South Chamorro serpentinite seamounts on the basis of depletion of sulfate and enrichment of dissolved sulfide in pore water. However, the vertical distribution of sulfate-reducing microorganisms and the origin of sulfate are still uncertain. To address these issues, we analyzed quadruple sulfur isotopes of sulfide minerals and pore water sulfate in the upper 56 m of sedimentary sequences at the summit of the S. Chamorro Seamount and those of dissolved sulfate in upwelling fluids collected as deep as 202 mbsf (meters below the seafloor) in a cased hole near the summit of the same seamount. The depth profiles of the concentrations and the δ34S and Δ33S‧ values of sulfide minerals and pore water sulfate indicate microbial sulfate reduction as deep as 30 mbsf. Further, apparent isotopic fractionations (34ε) and exponents of mass dependent relationships (33λ) during sulfate reduction are estimated to be 62 ± 14‰ and 0.512 ± 0.002, respectively. The upwelling fluids show both the chlorine depletion relative to seawater and the negative δ15N values of ammonia (-4‰). Although these signatures point to dehydration of the subducting oceanic plate, the negative Δ33S‧ values of sulfate (-0.16‰ to -0.26‰ with analytical errors of ±0.01‰) are unlikely to originate from surrounding modern crusts. Instead, sulfate in the upwelling fluid likely possess non-mass-dependent (NMD) sulfur. Because NMD sulfur was produced primarily in the Archean atmosphere, our

  6. Effect of ultramafic intrusions and associated mineralized rocks on the aqueous geochemistry of the Tangle Lakes Area, Alaska: Chapter C in Studies by the U.S. Geological Survey in Alaska, 2011

    Science.gov (United States)

    Wang, Bronwen; Gough, Larry P.; Wanty, Richard B.; Lee, Gregory K.; Vohden, James; O’Neill, J. Michael; Kerin, L. Jack

    2013-01-01

    Stream water was collected at 30 sites within the Tangle Lakes area of the Delta mineral belt in Alaska. Sampling focused on streams near the ultramafic rocks of the Fish Lake intrusive complex south of Eureka Creek and the Tangle Complex area east of Fourteen Mile Lake, as well as on those within the deformed metasedimentary, metavolcanic, and intrusive rocks of the Specimen Creek drainage and drainages east of Eureka Glacier. Major, minor, and trace elements were analyzed in aqueous samples for this reconnaissance aqueous geochemistry effort. The lithologic differences within the study area are reflected in the major-ion chemistry of the water. The dominant major cation in streams draining mafic and ultramafic rocks is Mg2+; abundant Mg and low Ca in these streams reflect the abundance of Mg-rich minerals in these intrusions. Nickel and Cu are detected in 84 percent and 87 percent of the filtered samples, respectively. Nickel and Cu concentrations ranged from Ni life criteria; however, Cu concentrations exceed the hardness-based criteria for both chronic and acute exposure at some sites. The entire rare earth element (REE) suite is found in samples from the Specimen Creek sites MH5, MH4, and MH6 and, with the exception of Tb and Tm, at site MH14. These samples were all collected within drainages containing or downstream from Tertiary gabbro, diabase, and metagabbro (Trgb) exposures. Chondrite and source rock fractionation profiles for the aqueous samples were light rare earth element depleted, with negative Ce and Eu anomalies, indicating fractionation of the REE during weathering. Fractionation patterns indicate that the REE are primarily in the dissolved, as opposed to colloidal, phase.

  7. Beach rock from Goa Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.; Wagle, B.G.

    constituents of beach rock found along Goa coast is dealt with in detail. While discussing the various views on its origin, it is emphasized that the process of cementation is chiefly controlled by ground water evaporation, inorganic precipitation and optimum...

  8. The Chronology of Rock Art

    Indian Academy of Sciences (India)

    Such phases are tentatively ascribed to different archaeological cultures on the basis of the contextual availability, stylistic similarities and so on. Ethnographic analogies are also attempted in the dating of rock art .

  9. Chemical methods of rock analysis

    National Research Council Canada - National Science Library

    Jeffery, P. G; Hutchison, D

    1981-01-01

    A practical guide to the methods in general use for the complete analysis of silicate rock material and for the determination of all those elements present in major, minor or trace amounts in silicate...

  10. Heat production in granitic rocks

    DEFF Research Database (Denmark)

    Artemieva, Irina; Thybo, Hans; Jakobsen, Kiki

    2017-01-01

    Granitic rocks play special role in the dynamics and evolution of the Earth and its thermal regime. First, their compositional variability, reflected in the distribution of concentrations of radiogenic elements, provides constraints on global differentiation processes and large scale planetary...... evolution, where emplacement of granites is considered a particularly important process for the formation of continental crust. Second, heat production by radioactive decay is among the main heat sources in the Earth. Therefore knowledge of heat production in granitic rocks is pivotal for thermal modelling...... of the continental lithosphere, given that most radiogenic elements are concentrated in granitic rocks of the upper continental crust whereas heat production in rocks of the lower crust and lithospheric mantle is negligible. We present and analyze a new global database GRANITE2017 (with about 500 entries...

  11. Defending dreamer’s rock

    OpenAIRE

    Beck, Günter U.

    2007-01-01

    Defending dreamer’s rock : Geschichte, Geschichtsbewusstsein und Geschichtskultur im Native drama der USA und Kanadas. - Trier : WVT Wiss. Verl. Trier, 2007. - 445 S. - (CDE - Studies ; 14). - Zugl.: Augsburg, Univ., Diss., 2006

  12. Osmium Isotopic Evolution of the Mantle Sources of Precambrian Ultramafic Rocks

    Science.gov (United States)

    Gangopadhyay, A.; Walker, R. J.

    2006-12-01

    The Os isotopic composition of the modern mantle, as recorded collectively by ocean island basalts, mid- oceanic ridge basalts (MORB) and abyssal peridotites, is evidently highly heterogeneous (γ Os(I) ranging from +25). One important question, therefore, is how and when the Earth's mantle developed such large-scale Os isotopic heterogeneities. Previous Os isotopic studies of ancient ultramafic systems, including komatiites and picrites, have shown that the Os isotopic heterogeneity of the terrestrial mantle can be traced as far back as the late-Archean (~ 2.7-2.8 Ga). This observation is based on the initial Os isotopic ratios obtained for the mantle sources of some of the ancient ultramafic rocks determined through analyses of numerous Os-rich whole-rock and/or mineral samples. In some cases, the closed-system behavior of these ancient ultramafic rocks was demonstrated via the generation of isochrons of precise ages, consistent with those obtained from other radiogenic isotopic systems. Thus, a compilation of the published initial ^{187}Os/^{188}Os ratios reported for the mantle sources of komatiitic and picritic rocks is now possible that covers a large range of geologic time spanning from the Mesozoic (ca. 89 Ma Gorgona komatiites) to the Mid-Archean (e.g., ca. 3.3 Ga Commondale komatiites), which provides a comprehensive picture of the Os isotopic evolution of their mantle sources through geologic time. Several Precambrian komatiite/picrite systems are characterized by suprachondritic initial ^{187}Os/^{188}Os ratios (e.g., Belingwe, Kostomuksha, Pechenga). Such long-term enrichments in ^{187}Os of the mantle sources for these rocks may be explained via recycling of old mafic oceanic crust or incorporation of putative suprachondritic outer core materials entrained into their mantle sources. The relative importance of the two processes for some modern mantle-derived systems (e.g., Hawaiian picrites) is an issue of substantial debate. Importantly, however, the

  13. Preservation of Fe Isotope Proxies in the Rock Record

    Science.gov (United States)

    Johnson, C.; Beard, B.; Valley, J.; Valaas, E.

    2005-12-01

    Iron isotope variations provide powerful constraints on redox conditions and pathways involved during biogeochemical cycling of Fe in surface and near-surface environments. The relative isotopic homogeneity of igneous rocks and most bulk weathering products contrasts with the significant isotopic variations (4 per mil in 56Fe/54Fe) that accompany oxidation of Fe(II)aq, precipitation of sulfides, and reduction by bacteria. These isotopic variations often reflect intrinsic (equilibrium) Fe isotope fractionations between minerals and aqueous species whose interactions may be directly or indirectly catalyzed by bacteria. In addition, Fe isotope exchange may be limited between reactive Fe pools in low-temperature aqueous-sediment environments, fundamentally reflecting disequilibrium effects. In the absence of significant sulfide, dissimilatory Fe(III) reduction by bacteria produces relatively low 56Fe/54Fe ratios for Fe(II)aq and associated biogenic minerals such as magnetite and siderite. In contrast, Fe(II)aq that exchanges with Fe sulfides (FeS and pyrite) is relatively enriched in 56Fe/54Fe ratios. In modern and ancient environments, anoxic diagenesis tends to produce products that have low 56Fe/54Fe ratios, whereas oxidation of Fe(II)aq from hydrothermal sources tends to produce ferric Fe products that have high 56Fe/54Fe ratios. Redox cycling by bacteria tends to produce reactive ferric Fe reservoirs that have low 56Fe/54Fe ratios. Application of Fe isotopes as a proxy for redox conditions in the ancient rock record depends upon the preservation potential during metamorphism, given the fact that most Archean sedimentary sequences have been subjected to regional greenschist- to granulite-facies metamorphism. The 1.9 Ga banded iron formations (BIFs) of the Lake Superior region that are intruded by large ~1 Ga intrusions (e.g., Duluth gabbro) provide a test of the preservation potential for primary, low-temperature Fe isotope variations in sedimentary rocks. 56Fe/54

  14. Predicting rock bursts in mines

    Science.gov (United States)

    Spall, H.

    1979-01-01

    In terms of lives lost, rock bursts in underground mines can be as hazardous as earthquakes on the surface. So it is not surprising that fo the last 40 years the U.S Bureau of Mines has been using seismic methods for detecting areas in underground mines where there is a high differential stress which could lead to structural instability of the rock mass being excavated.

  15. Thermally induced rock stress increment and rock reinforcement response

    International Nuclear Information System (INIS)

    Hakala, M.; Stroem, J.; Nujiten, G.; Uotinen, L.; Siren, T.; Suikkanen, J.

    2014-07-01

    This report describes a detailed study of the effect of thermal heating by the spent nuclear fuel containers on the in situ rock stress, any potential rock failure, and associated rock reinforcement strategies for the Olkiluoto underground repository. The modelling approach and input data are presented together repository layout diagrams. The numerical codes used to establish the effects of heating on the in situ stress field are outlined, together with the rock mass parameters, in situ stress values, radiogenic temperatures and reinforcement structures. This is followed by a study of the temperature and stress evolution during the repository's operational period and the effect of the heating on the reinforcement structures. It is found that, during excavation, the maximum principal stress is concentrated at the transition areas where the profile changes and that, due to the heating from the deposition of spent nuclear fuel, the maximum principal stress rises significantly in the tunnel arch area of NW/SW oriented central tunnels. However, it is predicted that the rock's crack damage (CD, short term strength) value of 99 MPa will not be exceeded anywhere within the model. Loads onto the reinforcement structures will come from damaged and loosened rock which is assumed in the modelling as a free rock wedge - but this is very much a worst case scenario because there is no guarantee that rock cracking would form a free rock block. The structural capacity of the reinforcement structures is described and it is predicted that the current quantity of the rock reinforcement is strong enough to provide a stable tunnel opening during the peak of the long term stress state, with damage predicted on the sprayed concrete liner. However, the long term stability and safety can be improved through the implementation of the principles of the Observational Method. The effect of ventilation is also considered and an additional study of the radiogenic heating effect on the brittle

  16. Thermally induced rock stress increment and rock reinforcement response

    Energy Technology Data Exchange (ETDEWEB)

    Hakala, M. [KMS Hakala Oy, Nokia (Finland); Stroem, J.; Nujiten, G.; Uotinen, L. [Rockplan, Helsinki (Finland); Siren, T.; Suikkanen, J.

    2014-07-15

    This report describes a detailed study of the effect of thermal heating by the spent nuclear fuel containers on the in situ rock stress, any potential rock failure, and associated rock reinforcement strategies for the Olkiluoto underground repository. The modelling approach and input data are presented together repository layout diagrams. The numerical codes used to establish the effects of heating on the in situ stress field are outlined, together with the rock mass parameters, in situ stress values, radiogenic temperatures and reinforcement structures. This is followed by a study of the temperature and stress evolution during the repository's operational period and the effect of the heating on the reinforcement structures. It is found that, during excavation, the maximum principal stress is concentrated at the transition areas where the profile changes and that, due to the heating from the deposition of spent nuclear fuel, the maximum principal stress rises significantly in the tunnel arch area of NW/SW oriented central tunnels. However, it is predicted that the rock's crack damage (CD, short term strength) value of 99 MPa will not be exceeded anywhere within the model. Loads onto the reinforcement structures will come from damaged and loosened rock which is assumed in the modelling as a free rock wedge - but this is very much a worst case scenario because there is no guarantee that rock cracking would form a free rock block. The structural capacity of the reinforcement structures is described and it is predicted that the current quantity of the rock reinforcement is strong enough to provide a stable tunnel opening during the peak of the long term stress state, with damage predicted on the sprayed concrete liner. However, the long term stability and safety can be improved through the implementation of the principles of the Observational Method. The effect of ventilation is also considered and an additional study of the radiogenic heating effect on the

  17. Finding the Needles in the Haystacks: High-Fidelity Models of the Modern and Archean Solar System for Simulating Exoplanet Observations

    Science.gov (United States)

    Roberge, Aki; Rizzo, Maxime J.; Lincowski, Andrew P.; Arney, Giada N.; Stark, Christopher C.; Robinson, Tyler D.; Snyder, Gregory F.; Pueyo, Laurent; Zimmerman, Neil T.; Jansen, Tiffany; hide

    2017-01-01

    We present two state-of-the-art models of the solar system, one corresponding to the present day and one to the Archean Eon 3.5 billion years ago. Each model contains spatial and spectral information for the star, the planets, and the interplanetary dust, extending to 50 au from the Sun and covering the wavelength range 0.3-2.5 micron. In addition, we created a spectral image cube representative of the astronomical backgrounds that will be seen behind deep observations of extrasolar planetary systems, including galaxies and Milky Way stars. These models are intended as inputs to high-fidelity simulations of direct observations of exoplanetary systems using telescopes equipped with high-contrast capability. They will help improve the realism of observation and instrument parameters that are required inputs to statistical observatory yield calculations, as well as guide development of post-processing algorithms for telescopes capable of directly imaging Earth-like planets.

  18. Archean and proterozoic in the West-European Hercynian chain: isotopic geochemistry (Sr-Nd-Pb) and U-Pb geochronology on zircons

    International Nuclear Information System (INIS)

    Guerrot, C.

    1989-01-01

    The first part of this research thesis reports the study of isotopic (Sr-Nd-Pb) geochemistry and U-Pb geochronology on zircons in the immersed granulites of the Bay of Biscay: U-Pb geochronology on zircons, Nd isotopic geochemistry, Sr isotopic geochemistry, common Pb, Rb-Sr, Sm-Nd and rare earth data on minerals, comparison with other European granulites, comparison with West-Africa, study of Archean and proterozoic in the Hercynian chain. The second part reports the study of the U-Pb geochronology on zircon in the Cadomian, and the third part addresses the Sr-Nd isotopic geochemistry of some Cadomian granitoid, and the crust contamination in different regions [fr

  19. Heat production in an Archean crustal profile and implications for heat flow and mobilization of heat-producing elements

    Science.gov (United States)

    Ashwal, L. D.; Morgan, P.; Kelley, S. A.; Percival, J. A.

    1987-01-01

    Concentrations of heat producing elements (Th, U, and K) in 58 samples representative of the main lithologies in a 100-km transect of the Superior Province of the Canadian Shield have been obtained. The relatively large variation in heat production found among the silicic plutonic rocks is shown to correlate with modal abundances of accessory minerals, and these variations are interpreted as premetamorphic. The present data suggest fundamental differences in crustal radioactivity distributions between granitic and more mafic terrains, and indicate that a previously determined apparently linear heat flow-heat production relationship for the Kapuskasing area does not relate to the distribution of heat production with depth.

  20. Evaluation of Rock Bolt Support for Polish Hard Rock Mines

    Science.gov (United States)

    Skrzypkowski, Krzysztof

    2018-03-01

    The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead "Olkusz - Pomorzany" mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt "Olkusz - 20A" is able to overcome the load.The second purpose of the study was to obtain load - displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.

  1. Seismic response of rock joints and jointed rock mass

    International Nuclear Information System (INIS)

    Ghosh, A.; Hsiung, S.M.; Chowdhury, A.H.

    1996-06-01

    Long-term stability of emplacement drifts and potential near-field fluid flow resulting from coupled effects are among the concerns for safe disposal of high-level nuclear waste (HLW). A number of factors can induce drift instability or change the near-field flow patterns. Repetitive seismic loads from earthquakes and thermal loads generated by the decay of emplaced waste are two significant factors. One of two key technical uncertainties (KTU) that can potentially pose a high risk of noncompliance with the performance objectives of 10 CFR Part 60 is the prediction of thermal-mechanical (including repetitive seismic load) effects on stability of emplacement drifts and the engineered barrier system. The second KTU of concern is the prediction of thermal-mechanical-hydrological (including repetitive seismic load) effects on the host rock surrounding the engineered barrier system. The Rock Mechanics research project being conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) is intended to address certain specific technical issues associated with these two KTUs. This research project has two major components: (i) seismic response of rock joints and a jointed rock mass and (ii) coupled thermal-mechanical-hydrological (TMH) response of a jointed rock mass surrounding the engineered barrier system (EBS). This final report summarizes the research activities concerned with the repetitive seismic load aspect of both these KTUs

  2. 30 CFR 57.3461 - Rock bursts.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons to...

  3. Isotopic data bearing on the origin of Mesozoic and Tertiary granitic rocks in the western United States

    International Nuclear Information System (INIS)

    DePaolo, D.J.; Farmer, G.L.

    1984-01-01

    A regional survey of initial Nd and Sr isotopic compositions has been done on Mesozoic and Tertiary granitic rocks from a 500 000 km 2 area in California, Nevada, Utah, Arizona, and Colorado. The plutons, which range in composition from quartz diorite to monzogranite, are intruded into accreted oceanic geosynclinal terrains in the west and north and into Precambrian basement in the east. Broad geographic coverage allows the data to be interpreted in the context of the regional pre-Mesozoic crustal structure. Initial Nd isotopic compositions exhibit a huge range, encompassing values typical of oceanic magmatic arcs and Archean basement. The sources of the magmas can be inferred from the systematic geographic variability of Nd isotopic compositions. The plutons in the accreted terrains represent mantle-derived magma that assimilated crust while differentiating at deep levels. Those emplaced into Precambrian basement are mainly derived from the crust. The regional patterns can be understood in terms of: (1) the flux of mantle magma entering the crust; (2) crustal thickness; and (3) crustal age. The mantle magma flux apparently decreased inland; in the main batholith belts purely crustal granitic rocks are not observed because the flux was too large. Inland, crustal granite is common because mantle magma was scarce and the crust was thick, and hot enough to melt. The epsilonsub(Nd) values of peraluminous granite formed by melting of the Precambrian basement depend on the age of the local basement source. (author)

  4. The Khida terrane - Geology of Paleoproterozoic rocks in the Muhayil area, eastern Arabian Shield, Saudi Arabia

    Science.gov (United States)

    Stoeser, D.B.; Whitehouse, M.J.; Stacey, J.S.

    2001-01-01

    The bulk of the Arabian Shield of Saudi Arabia is underlain by Neoproterozoic terranes of oceanic affinity that were accreted during Pan-African time (about 680- 640Ma). Geologicalmappingandisotopicinvestigations during the 1980’s,however, provided the first evidence for Paleoproterozoic continental crust within the east- central part of the shield in Saudi Arabia. These studies delineated an older basement domain, herein referred to as the Khida terrane (Fig. l), which is defined as that part of the southern Afif composite terrane underlain by Paleoproterozoicto Archean continental crust (Stoeser and Stacey, 1988). The isotopic and geochronologic work to support our current studies within the Khida terrane are discussed in a companion abstract (Whitehouse et al., this volume). The regional geology and geochronology of the region has been summarized in detail by Johnson (1996). The current study is based on the continued use of samples previously collected in the Khida area by the authors and others as well as new field work conducted by us in 1999. This work further defines the occurrence of late Paleoproterozoic rocks at Jabal Muhayil, which is located at the eastern margin of the exposed terrane (Fig. 1). Our isotopic work is at an early stage and this abstract partly relates geologic problems that remain to be resolved. 

  5. Current status of crushed rock and whole rock column studies

    International Nuclear Information System (INIS)

    Vine, E.N.; Daniels, W.R.; Rundberg, R.S.; Thompson, J.L.

    1980-01-01

    Measurements on a large number of crushed rock columns of tuff, granite, and argillite are discussed. The isotopes 85 Sr, 137 Cs, 133 Ba, 141 Ce, 152 Eu, /sup 95m/Tc, and 233 U were used. Flow rates were varied from approx. 30 to approx. 30000 m/y. Other parameters studied include isotope concentration and atmosphere. The sorption ratios calculated were compared with batch sorption ratios on the same samples. Methods of studying the movement of radionuclides through whole rock cores are described. The problems associated with sealing the cores to prevent leaking along the exterior surface and one possible solution are discussed. The strontium sorption ratio obtained by elution of one solid tuff core is compared with the batch and crushed rock column sorption ratios

  6. Rock Pore Structure as Main Reason of Rock Deterioration

    Directory of Open Access Journals (Sweden)

    Ondrášik Martin

    2014-03-01

    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.

  7. Fracture characteristics in Japanese rock

    International Nuclear Information System (INIS)

    Ijiri, Yuji; Sawada, Atsushi; Akahori, Kuniaki

    1999-11-01

    It is crucial for the performance assessment of geosphere to evaluate the characteristics of fractures that can be dominant radionuclide migration pathways from a repository to biosphere. This report summarizes the characteristics of fractures obtained from broad literature surveys and the fields surveys at the Kamaishi mine in northern Japan and at outcrops and galleries throughout the country. The characteristics of fractures described in this report are fracture orientation, fracture shape, fracture frequency, fracture distribution in space, transmissivity of fracture, fracture aperture, fracture fillings, alteration halo along fracture, flow-wetted surface area in fracture, and the correlation among these characteristics. Since granitic rock is considered the archetype fractured media, a large amount of fracture data is available in literature. In addition, granitic rock has been treated as a potential host rock in many overseas programs, and has JNC performed a number of field observations and experiments in granodiorite at the Kamaishi mine. Therefore, the characteristics of fractures in granitic rock are qualitatively and quantitatively clarified to some extent in this report, while the characteristics of fractures in another rock types are not clarified. (author)

  8. Hot dry rock heat mining

    International Nuclear Information System (INIS)

    Duchane, D.V.

    1992-01-01

    Geothermal energy utilizing fluids from natural sources is currently exploited on a commercial scale at sites around the world. A much greater geothermal resource exists, however, in the form of hot rock at depth which is essentially dry. This hot dry rock (HDR) resource is found almost everywhere, but the depth at which usefully high temperatures are reached varies from place to place. The technology to mine the thermal energy from HDR has been under development for a number of years. Using techniques adapted from the petroleum industry, water is pumped at high pressure down an injection well to a region of usefully hot rock. The pressure forces open natural joints to form a reservoir consisting of a small amount of water dispensed in a large volume of hot rock. This reservoir is tapped by second well located at some distance from the first, and the heated water is brought to the surface where its thermal energy is extracted. The same water is then recirculated to mine more heat. Economic studies have indicated that it may be possible to produce electricity at competitive prices today in regions where hot rock is found relatively close to the surface

  9. A reassessment of the Archean-Mesoproterozoic tectonic development of the southeastern Chhattisgarh Basin, Central India through detailed aeromagnetic analysis

    Science.gov (United States)

    Sridhar, M.; Ramesh Babu, V.; Markandeyulu, A.; Raju, B. V. S. N.; Chaturvedi, A. K.; Roy, M. K.

    2017-08-01

    We constrained the geological framework over polydeformed Paleoproterozoic Sonakhan Greenstone Belt and addressed the tectonic evolution of Singhora basin in the fringes of Bastar Craton, central India by utilizing aeromagnetic data interpretation, 2.5D forward modelling and 3D magnetic susceptibility inversions. The Sonakhan Greenstone Belt exposes volcano-sedimentary sequences of the Sonakhan Group within NNW-SSE to NW-SE trending linear belts surrounded by granite gneisses, which are unconformably overlain by sedimentary rocks of Chhattisgarh Basin. The orientations of aeromagnetic anomalies are coincident with geological trends and appear to correlate with lithology and geologic structure. Regional magnetic anomalies and lineaments reveal both NNW-SSE and NE-SW trends. Prominent E-W trending linear, high amplitude magnetic anomalies are interpreted as the Trans-Chhattisgarh Aeromagnetic Lineament (TCAL). NW-SE trending aeromagnetic signatures related to Sonakhan Greenstone Belt extends below the Singhora sedimentary rocks and forms the basement in the west. The analysis suggests that TCAL is a block fault with northern block down-thrown and affected the basement rocks comprising the Sonakhan Greenstone Belt and Samblapur Granitoids. The episode of faulting represented by the TCAL is pre-Singhora sedimentation and played a vital role in basin evolution. The basement configuration image generated by estimates of depth to magnetic basement suggests a complex pattern of NNE-SSW to NE-SW trending depressions separated by a linear N-S trending basement ridge. It is inferred from the 3D magnetic susceptibility inversion that the thickness of sediments is more towards the eastern basin margin and the N-S ridge is a manifestation of post sedimentary faulting. Results of 2.5D modelling of a WNW-ESE profile across the Singhora Basin combined with results from 3D inversion suggest suggests the basin subsidence was controlled by NE-SW trending regional faults in an active

  10. Thermal expansion of granite rocks

    International Nuclear Information System (INIS)

    Stephansson, O.

    1978-04-01

    The thermal expansion of rocks is strongly controlled by the thermal expansion of the minerals. The theoretical thermal expansion of the Stripa Granite is gound to be 21 . 10 -6 [deg C] -1 at 25 deg C and 38 . 10 -6 [deg C] -1 at 400 deg C. The difference in expansion for the rock forming minerals causes micro cracking at heating. The expansion due to micro cracks is found to be of the same order as the mineral expansion. Most of the micro cracks will close at pressures of the order of 10 - 20 MPa. The thermal expansion of a rock mass including the effect of joints is determined in the pilot heater test in the Stripa Mine

  11. Uranium endowments in phosphate rock

    International Nuclear Information System (INIS)

    Ulrich, Andrea E.; Schnug, Ewald; Prasser, Horst-Michael; Frossard, Emmanuel

    2014-01-01

    This study seeks to identify and specify the components that make up the prospects of U recovery from phosphate rock. A systems approach is taken. The assessment includes i) reviewing past recovery experience and lessons learned; ii) identifying factors that determine recovery; and iii) establishing a contemporary evaluation of U endowments in phosphate rock reserves, as well as the available and recoverable amounts from phosphate rock and phosphoric acid production. We find that in the past, recovery did not fulfill its potential and that the breakup of the Soviet Union worsened then-favorable recovery market conditions in the 1990s. We find that an estimated 5.7 million tU may be recoverable from phosphate rock reserves. In 2010, the recoverable tU from phosphate rock and phosphoric acid production may have been 15,000 tU and 11,000 tU, respectively. This could have filled the world U supply-demand gap for nuclear energy production. The results suggest that the U.S., Morocco, Tunisia, and Russia would be particularly well-suited to recover U, taking infrastructural considerations into account. We demonstrate future research needs, as well as sustainability orientations. We conclude that in order to promote investment and production, it seems necessary to establish long-term contracts at guaranteed prices, ensuring profitability for phosphoric acid producers. - Highlights: • We identify components that underlie the recovery of uranium from phosphate rock. • We estimate that 11,000 tU may have been recoverable from phosphoric acid in 2010. • Recovery is a resource conservation and environmental pollution control strategy. • To ensure investment in recovery technology, profitability needs to be secured

  12. Uranium deposits in granitic rocks

    International Nuclear Information System (INIS)

    Nishimori, R.K.; Ragland, P.C.; Rogers, J.J.W.; Greenberg, J.K.

    1977-01-01

    This report is a review of published data bearing on the geology and origin of uranium deposits in granitic, pegmatitic and migmatitic rocks with the aim of assisting in the development of predictive criteria for the search for similar deposits in the U.S. Efforts were concentrated on the so-called ''porphyry'' uranium deposits. Two types of uranium deposits are primarily considered: deposits in pegmatites and alaskites in gneiss terrains, and disseminations of uranium in high-level granites. In Chapter 1 of this report, the general data on the distribution of uranium in igneous and metamorphic rocks are reviewed. Chapter 2 contains some comments on the classification of uranium deposits associated with igneous rocks and a summary of the main features of the geology of uranium deposits in granites. General concepts of the behavior of uranium in granites during crustal evolution are reviewed in Chapter 3. Also included is a discussion of the relationship of uranium mineralization in granites to the general evolution of mobile belts, plus the influence of magmatic and post-magmatic processes on the distribution of uranium in igneous rocks and related ore deposits. Chapter 4 relates the results of experimental studies on the crystallization of granites to some of the geologic features of uranium deposits in pegmatites and alaskites in high-grade metamorphic terrains. Potential or favorable areas for igneous uranium deposits in the U.S.A. are delineated in Chapter 5. Data on the geology of specific uranium deposits in granitic rocks are contained in Appendix 1. A compilation of igneous rock formations containing greater than 10 ppM uranium is included in Appendix 2. Appendix 3 is a report on the results of a visit to the Roessing area. Appendix 4 is a report on a field excursion to eastern Canada

  13. Uranium endowments in phosphate rock

    Energy Technology Data Exchange (ETDEWEB)

    Ulrich, Andrea E., E-mail: andrea.ulrich@env.ethz.ch [Institute for Environmental Decisions (IED), Natural and Social Science Interface, ETH Zurich Universitässtrasse 22, 8092 Zurich (Switzerland); Institute for Agricultural Sciences, Plant Nutrition, ETH Zurich, Eschikon 33, 8315 Lindau (Switzerland); Schnug, Ewald, E-mail: e.schnug@tu-braunschweig.de [Department of Life Sciences, Technical University of Braunschweig, Pockelsstraße 14, D-38106 Braunschweig (Germany); Prasser, Horst-Michael, E-mail: prasser@lke.mavt.ethz.ch [Institute of Energy Technology, Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8092 Zurich (Switzerland); Frossard, Emmanuel, E-mail: emmanuel.frossard@usys.ethz.ch [Institute for Agricultural Sciences, Plant Nutrition, ETH Zurich, Eschikon 33, 8315 Lindau (Switzerland)

    2014-04-01

    This study seeks to identify and specify the components that make up the prospects of U recovery from phosphate rock. A systems approach is taken. The assessment includes i) reviewing past recovery experience and lessons learned; ii) identifying factors that determine recovery; and iii) establishing a contemporary evaluation of U endowments in phosphate rock reserves, as well as the available and recoverable amounts from phosphate rock and phosphoric acid production. We find that in the past, recovery did not fulfill its potential and that the breakup of the Soviet Union worsened then-favorable recovery market conditions in the 1990s. We find that an estimated 5.7 million tU may be recoverable from phosphate rock reserves. In 2010, the recoverable tU from phosphate rock and phosphoric acid production may have been 15,000 tU and 11,000 tU, respectively. This could have filled the world U supply-demand gap for nuclear energy production. The results suggest that the U.S., Morocco, Tunisia, and Russia would be particularly well-suited to recover U, taking infrastructural considerations into account. We demonstrate future research needs, as well as sustainability orientations. We conclude that in order to promote investment and production, it seems necessary to establish long-term contracts at guaranteed prices, ensuring profitability for phosphoric acid producers. - Highlights: • We identify components that underlie the recovery of uranium from phosphate rock. • We estimate that 11,000 tU may have been recoverable from phosphoric acid in 2010. • Recovery is a resource conservation and environmental pollution control strategy. • To ensure investment in recovery technology, profitability needs to be secured.

  14. First report of garnet corundum rocks from southern India: Implications for prograde high-pressure (eclogite-facies?) metamorphism

    Science.gov (United States)

    Shimpo, Makoto; Tsunogae, Toshiaki; Santosh, M.

    2006-02-01

    . Evidence for such high-pressure metamorphism followed by UHT conditions along a single clockwise exhumation path is the first report from southern India. The Namakkal area occurs within the central domain of the PCSS, which defines the probable collisional suture between the Archean craton in the north and the Proterozoic Madurai Block in the south. We propose that the rocks reported in this study testify to metamorphism at mantle depths (eclogite-facies) and their subsequent heating at extreme thermal conditions during collisional orogenic event and subsequent rapid exhumation associated with the final suturing of the Gondwana assembly in the late Pan-African. The high-pressure metamorphism and subsequent UHT event reported in this study have important bearing on the tectonic evolution of the continental deep crust in southern India.

  15. Evaluation of Rock Joint Coefficients

    Science.gov (United States)

    Audy, Ondřej; Ficker, Tomáš

    2017-10-01

    A computer method for evaluation of rock joint coefficients is described and several applications are presented. The method is based on two absolute numerical indicators that are formed by means of the Fourier replicas of rock joint profiles. The first indicator quantifies the vertical depth of profiles and the second indicator classifies wavy character of profiles. The absolute indicators have replaced the formerly used relative indicators that showed some artificial behavior in some cases. This contribution is focused on practical computations testing the functionality of the newly introduced indicators.

  16. Ultrasonically assisted drilling of rocks

    Science.gov (United States)

    Mikhailova, N. V.; Onawumi, P. Y.; Roy, A.; Silberschmidt, V. V.

    2018-05-01

    Conventional drilling of rocks can generate significant damage in the drilled material; a material layer is often split off a back surface of a sample during drilling, negatively affecting its strength. To improve finish quality, ultrasonically assisted drilling (UAD) was employed in two rocks - sandstone and marble. Damage areas in both materials were reduced in UAD when compared to conventional drilling. Reductions in a thrust force and a torque reduction were observed only for UAD in marble; ultrasonic assistance in sandstone drilling did not result in improvements in this regard.

  17. Rock mechanics studies for SMES

    International Nuclear Information System (INIS)

    Haimson, B.C.

    1981-01-01

    Superconducting magnetic energy storage (SMES) systems capable of storing thousands of MWh develop tremendous magnetically induced forces when charged. To prevent rutpure of the magnets these forces must be confined. Bedrock offers a practical and relatively inexpensive magnet containment structure. This paper examines the need for rock mechanics research in connection with the construction and use of SMES rock caverns; the unique problems related to housing superconducting magnets in bedrock; site investigations of granite, quartzite and dolomite deposits in Wisconsin; and cavern design requirements to assure cavern stability and limited deformation under the expected mechanical leads. Recommendations are made for siting SMES caverns

  18. Source rock potential of middle cretaceous rocks in Southwestern Montana

    Science.gov (United States)

    Dyman, T.S.; Palacas, J.G.; Tysdal, R.G.; Perry, W.J.; Pawlewicz, M.J.

    1996-01-01

    The middle Cretaceous in southwestern Montana is composed of a marine and nonmarine succession of predominantly clastic rocks that were deposited along the western margin of the Western Interior Seaway. In places, middle Cretaceous rocks contain appreciable total organic carbon (TOC), such as 5.59% for the Mowry Shale and 8.11% for the Frontier Formation in the Madison Range. Most samples, however, exhibit less than 1.0% TOC. The genetic or hydrocarbon potential (S1+S2) of all the samples analyzed, except one, yield less than 1 mg HC/g rock, strongly indicating poor potential for generating commercial amounts of hydrocarbons. Out of 51 samples analyzed, only one (a Thermopolis Shale sample from the Snowcrest Range) showed a moderate petroleum potential of 3.1 mg HC/g rock. Most of the middle Cretaceous samples are thermally immature to marginally mature, with vitrinite reflectance ranging from about 0.4 to 0.6% Ro. Maturity is high in the Pioneer Mountains, where vitrinite reflectance averages 3.4% Ro, and at Big Sky Montana, where vitrinite reflectance averages 2.5% Ro. At both localities, high Ro values are due to local heat sources, such as the Pioneer batholith in the Pioneer Mountains.

  19. Soft Rock Yields Clues to Mars' Past

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1 This image taken by the Mars Exploration Rover Spirit shows the rock outcrop dubbed 'Clovis.' The rock was discovered to be softer than other rocks studied so far at Gusev Crater after the rover easily ground a hole into it with its rock abrasion tool. Spirit's solar panels can be seen in the foreground. This image was taken by the rover's navigation camera on sol 205 (July 31, 2004). Elemental Trio Found in 'Clovis' Figure 1 above shows that the interior of the rock dubbed 'Clovis' contains higher concentrations of sulfur, bromine and chlorine than basaltic, or volcanic, rocks studied so far at Gusev Crater. The data were taken by the Mars Exploration Rover Spirit's alpha particle X-ray spectrometer after the rover dug into Clovis with its rock abrasion tool. The findings might indicate that this rock was chemically altered, and that fluids once flowed through the rock depositing these elements.

  20. Review on the prevailing methods for the prediction of potential rock burst / rock spalling in tunnels

    OpenAIRE

    Panthi, Krishna Kanta

    2017-01-01

    Rock burst / rock spalling is among the prevailing stability challenges, which can be met while tunneling through hard rock mass. Especially, this is very relevant for the mountainous country like Norway where hard rock is dominating and many road, railway and hydropower tunnels have to be aligned deep into the mountain with steep valley slope topography. Tunnels passing beneath deep rock cover (overburden), in general, are subjected to high in-situ stresses. If the rock mass is relatively un...

  1. Simulation of rock deformation behavior

    Directory of Open Access Journals (Sweden)

    Я. И. Рудаев

    2016-12-01

    Full Text Available A task of simulating the deformation behavior of geomaterials under compression with account of over-extreme branch has been addressed. The physical nature of rock properties variability as initially inhomogeneous material is explained by superposition of deformation and structural transformations of evolutionary type within open nonequilibrium systems. Due to this the description of deformation and failure of rock is related to hierarchy of instabilities within the system being far from thermodynamic equilibrium. It is generally recognized, that the energy function of the current stress-strain state is a superposition of potential component and disturbance, which includes the imperfection parameter accounting for defects not only existing in the initial state, but also appearing under load. The equation of state has been obtained by minimizing the energy function by the order parameter. The imperfection parameter is expressed through the strength deterioration, which is viewed as the internal parameter of state. The evolution of strength deterioration has been studied with the help of Fokker – Planck equation, which steady form corresponds to rock statical stressing. Here the diffusion coefficient is assumed to be constant, while the function reflecting internal sliding and loosening of the geomaterials is assumed as an antigradient of elementary integration catastrophe. Thus the equation of state is supplemented with a correlation establishing relationship between parameters of imperfection and strength deterioration. While deformation process is identified with the change of dissipative media, coupled with irreversible structural fluctuations. Theoretical studies are proven with experimental data obtained by subjecting certain rock specimens to compression.

  2. Los abuelos de nuestro rock

    Directory of Open Access Journals (Sweden)

    Jacobo Celnik

    2016-12-01

    Full Text Available Los Yetis. Una bomba atómica a go go. La historia de los abuelos de nuestro rock. Diego Londoño; Pulso & Letra Editores, Instituto para el Desarrollo de Antioquia, Instituto de Cultura y Patrimonio de Antioquia, 2014, 98 págs., fotografías.

  3. Gas migration in argillaceous rock

    International Nuclear Information System (INIS)

    Alonso, E. E.; Olivella, S.

    2007-01-01

    The intrinsic gas permeability of fractured argillaceous rocks depends on the current structure of micro-cracks and fissures of the rock. They are a consequence of the initial state and the subsequent deformations induced by stress and gas pressure changes. Stresses are also coupled with fluid pressures and, therefore, gas flow and mechanical behaviour are intensely coupled. Laboratory experiments, aimed at determining intrinsic permeability, show the relevant effect of volumetric deformations induced by isotropic, as well as deviatoric stress changes. The relevance, in practice, of the flow-mechanical coupling is illustrated by means of some results obtained during the performance of the drift scale test (DST) in fractured tuff in the Yucca Mountain facility. The technique of embedding discontinuities in continuum thermo-hydro-mechanical elements is capable of reproducing observed features of gas flow migration in clayey rocks. An example is described. It is believed that the developed approach provides a powerful computational procedure to handle complex gas phenomena in clayey rocks. (author)

  4. Radioactivities (dose rates) of rocks in Japan

    International Nuclear Information System (INIS)

    Matsuda, Hideharu; Minato, Susumu

    1995-01-01

    The radioactive distribution (radiation doses) of major rocks in Japan was monitored to clarify the factors influencing terrestrial gamma-ray absorbed dose rates. The rock samples were reduced to powder and analyzed by well-type NaI(Tl) scintillation detector and pulse height analyzer. Terrestrial gamma-ray dose rates were estimated in terms of gamma radiation dose rate 1 m above the ground. The radioactivity concentration was highest in acidic rock which contains much SiO 2 among igneous rock, followed by neutral rock, basic rock, and ultrabasic rock. The radioactive concentration was 30-40% lower in acidic and clastic rocks than those of the world average concentration. Higher radioactive concentration was observed in soils than the parent rocks of sedimentary rock and metamorphic rock. The gamma radiation dose rate was in proportion to the radioactive concentration of the rocks. To clarify the radioactive effect in the change course of rocks into soils, comparative measurement of outcrop and soil radioactive concentrations is important. (S.Y.)

  5. Analysis of volcano rocks by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Sitek, J.; Dekan, J.

    2012-01-01

    In this work we have analysed the basalt rock from Mount Ba tur volcano situated on the Island of Bali in Indonesia.We compared our results with composition of basalt rocks from some other places on the Earth. (authors)

  6. Regulation of ROCK Activity in Cancer

    DEFF Research Database (Denmark)

    Morgan-Fisher, Marie; Wewer, Ulla M; Yoneda, Atsuko

    2013-01-01

    , these findings demonstrate additional modes to regulate ROCK activity. This review describes the molecular mechanisms of ROCK activity regulation in cancer, with emphasis on ROCK isoform-specific regulation and interaction partners, and discusses the potential of ROCKs as therapeutic targets in cancer.......Cancer-associated changes in cellular behavior, such as modified cell-cell contact, increased migratory potential, and generation of cellular force, all require alteration of the cytoskeleton. Two homologous mammalian serine/threonine kinases, Rho-associated protein kinases (ROCK I and II), are key...... regulators of the actin cytoskeleton acting downstream of the small GTPase Rho. ROCK is associated with cancer progression, and ROCK protein expression is elevated in several types of cancer. ROCKs exist in a closed, inactive conformation under quiescent conditions, which is changed to an open, active...

  7. Rock Slope Design Criteria : Executive Summary Report

    Science.gov (United States)

    2010-06-01

    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 that...

  8. Rock glaciers, Central Andes, Argentina, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — Primary rock glaciers are fed by avalanche chutes. At the El Salto rock glacier, surveys have been undertaken in order to determine the creep rate. Between 1981 and...

  9. Channelling of flow through fractures in rock

    International Nuclear Information System (INIS)

    Bourke, P.J.

    1987-05-01

    A method of mapping the channelling of flow in rock fractures formed by contacts between rock faces and of measuring the effective apertures of channels has been developed. Some typical results are given. (author)

  10. Epigenetic alterations of sedimentary rocks at deposits

    International Nuclear Information System (INIS)

    Komarova, G.V.; Kondrat'eva, I.A.; Zelenova, O.I.

    1980-01-01

    Notions are explained, and technique for studying epigenetic alterations of sedimentary rocks at uranium deposits is described. Main types of epigenetic transformations and their mineralogic-geochemical characteristics are considered. Rock alterations, accompanying uranium mineralization, can be related to 2 types: oxidation and reduction. The main mineralogic-geochemical property of oxidation transformations is epigenetic limonitization. Stratal limonitization in primary grey-coloured terrigenic rocks and in epigenetically reduced (pyritized) rocks, as well as in rock, subjected to epigenetic gleying, are characterized. Reduction type of epigenetic transformations is subdivided into sulphidic and non-sulphidic (gley) subtypes. Sulphidic transformations in grey-coloured terrigenic rocks with organic substance of carbonic row, in rocks, containing organic substance of oil row, sulphide transformations of sedimentary rocks, as well as gley transformations, are considered

  11. Uranium potential of precambrian rocks in the Raft River area of northwestern Utah and south-central Idaho. Final report

    International Nuclear Information System (INIS)

    Black, B.A.

    1980-09-01

    A total of 1214 geochemical samples were collected and analyzed. The sampling media included 334 waters, 616 stream sediments, and 264 rocks. In addition, some stratigraphic sections of Elba and Yost Quartzites and Archean metasedimentary rock were measured and sampled and numerous radiation determinations made of the various target units. Statistical evaluation of the geochemical data permitted recognition of 156 uranium anomalies, 52 in water, 79 in stream sediment, and 25 in rock. Geographically, 68 are located in the Grouse Creek Mountains, 43 in the Raft River Mountains, and 41 in the Albion Range. Interpretation of the various data leads to the conclusion that uranium anomalies relate to sparingly and moderately soluble uraniferous heavy minerals, which occur as sparse but widely distributed magmatic, detrital, and/or metamorphically segregated components in the target lithostratigraphic units. The uraniferous minerals known to occur and believed to account for the geochemical anomalies include allanite, monazite, zircon, and apatite. In some instances samarskite may be important. These heavy minerals contain uranium and geochemically related elements, such as Th, Ce, Y, and Zr, in sufficient quantities to account for both the conspicuous lithologic preference and the generally observed low amplitude of the anomalies. The various data generated in connection with this study, as well as those available in the published literature, collectively support the conclusion that the various Precambrian W and X lithostratigraphic units pre-selected for evaluation probably lack potential to host important Precambrian quartz-pebble conglomerate uranium deposits. Moreover it is also doubted that they possess any potential to host Proterozoic unconformity-type uranium deposits

  12. Lead-lead isotope method. Application to migmatites and associaded rocks of the region of Sao Jose dos Campos, SP

    International Nuclear Information System (INIS)

    Babinski, M.

    1988-01-01

    Establishment of chemical and analytical procedures, preparation and purification of reagents and the mounting of a clean laboratory (class 100) for the Pb-Pb isotope dating of whole rock and mineral samples are discussed in this work. Two different methods of dissolution of rock samples and chemical separation of lead using anionic resin were tried in a conventional chemical laboratory using analytical grade reagents. The samples analysed were paleossome and neossome of migmatites from Sao Jose dos Campos, SP, and from the results obtained the analytical method to be employed was chosen. The results obtained by this method agree well with those of the Geochronology Laboratory at Oxford, for the same samples. Applying the established analytical procedure, migmatites and associated gneisses from the region of Sao Jose dos Campos were dated by Pb/Pb method. Some of the samples were also dated by Rb-Sr method. The lead-lead isochron age of 2355 +- 85 M.a. (μ 1 = 8.33) for the paleossome may be interpreted as the age of the metamorphism for these rocks, which were formed probably during the Archean. The age data for the phacoidal gneisses show a similar geological evolution, whereas the 2414 +- 800 M.A. Pb-Pb isochron age for the protomylonitic gneisses indicates a disturbed Pb-Pb isotope system. The neossome samples define a Pb-Pb isochron age of 1388 +- 290 M.A. (μ1 = 8.15), which may be interpreted as the age of migmatization. The calculated Pb-Pb ages for two alkali feldspars from the migmatites are devoid of any geological significance. The age values obtained by the Rb-Sr isotope system for the neossome and paleossome of the migmatites agree with the Pb/Pb data within experimental errors. However, the study shows that results of the Rb-Sr data alone cannot be interpreted unambiguously with out comparison with data from other isotope systems. (author) [pt

  13. Analysis of volcano rock from Canary islands

    International Nuclear Information System (INIS)

    Sitek, J.; Sedlackova, K.; Dekan, J.

    2013-01-01

    In this work we have analyzed the basalt rock from Lanzarote, which is the easternmost island of the Canary Islands lying in the Atlantic Ocean and has a volcanic origin. It was born through fiery eruptions and has solidified lava streams as well as extravagant rock formations. We compared our results with composition of basalt rocks from some other places on the Earth. Different iron oxides created on the volcanic rocks during their weathering on the Earth surface has been also analyzed. (authors)

  14. High-pressure mechanical instability in rocks.

    Science.gov (United States)

    Byerlee, J D; Brace, W F

    1969-05-09

    At a confining pressure of a few kilobars, deformation of many sedimentary rocks, altered mafic rocks, porous volcanic rocks, and sand is ductile, in that instabilities leading to audible elastic shocks are absent. At pressures of 7 to 10 kilobars, however, unstable faulting and stick-slip in certain of these rocks was observed. This high pressure-low temperature instability might be responsible for earthquakes in deeply buried sedimentary or volcanic sequences.

  15. Depositional environments, provenance and paleoclimatic implications of Ordovician siliciclastic rocks of the Thango Formation, Spiti Valley, Tethys Himalaya, northern India

    Science.gov (United States)

    Rashid, Shaik A.; Ganai, Javid A.

    2018-05-01

    Recently published findings indicate that the Ordovician period has been much more dynamic than previously anticipated thus making this period significant in geological time. The Ordovician of India can best be studied in the Spiti region because the Spiti basin records the complete uninterrupted history of excellent marine sedimentary rocks starting from Cambrian to Paleogene which were deposited along the northern margin of India. Due to these reasons the geochemical data on the Ordovician rocks from the Spiti region is uncommon. The present geochemical study on the Ordovician Thango Formation (Sanugba Group) is mainly aimed to understand the provenance and the paleoclimatic conditions. The sandstones are the dominant lithology of the Thango Formation with intercalations of minor amount of shales. Detailed petrographic and sedimentological analysis of these rocks suggest that three major depositional environments, viz., fluvial, transitional and marine prevailed in the basin representing transgressive and regressive phases. The major and trace element ratios such as SiO2/Al2O3, K2O/Na2O and La-Th- Sc discrimination diagram suggest that these rocks were deposited in passive margin tectonic settings. Various geochemical discriminants and elemental ratios such as K2O/Na2O, Al2O3/TiO2, La/Sc, Th/Sc, Cr/Th, Zr/Sc, (Gd/Yb)N and pronounced negative Eu anomalies indicate the rocks to be the product of weathering of post-Archean granites. The striking similarities of the multi-elemental spider diagrams of the studied sediments and the Himalayan granitoids indicate that sediments are sourced from the Proterozoic orogenic belts of the Himalayan region. Chemical index of alteration (CIA) values of the studied sediments (55-72) suggest that the source rocks underwent low to moderate degree of chemical weathering. The span of the CIA values (55-72) recorded in the sediments from the Spiti region may have resulted from varying degrees of weathering conditions in the source area

  16. Rock Music's Place in the Library.

    Science.gov (United States)

    Politis, John

    1983-01-01

    Discussion of the importance of rock music as an expression of aural culture includes its history, rock music today, and the development of a rock music collection in the library (placement of collection and books which aid in developing a collection of permanent value). Three references are included. (EJS)

  17. Rock-degrading endophytic bacteria in cacti

    Science.gov (United States)

    M. Esther Puente; Ching Y. Li; Yoav Bashan

    2009-01-01

    A plant-bacterium association of the cardon cactus (Pachycereus pringlei) and endophytic bacteria promotes establishment of seedlings and growth on igneous rocks without soil. These bacteria weather several rock types and minerals, unbind significant amounts of useful minerals for plants from the rocks, fix in vitro N2. produce...

  18. Rock Art: Connecting to the Past.

    Science.gov (United States)

    Knipe, Marianne

    2001-01-01

    Presents an activity for fourth-grade students in which they learn about ancient art and create their own authentic-looking rock sculptures with pictograms, or painted images. Explains how the students create their own rocks and then paint a pictograph on the rocks with brown paint. (CMK)

  19. Mechanism of Rock Burst Occurrence in Specially Thick Coal Seam with Rock Parting

    Science.gov (United States)

    Wang, Jian-chao; Jiang, Fu-xing; Meng, Xiang-jun; Wang, Xu-you; Zhu, Si-tao; Feng, Yu

    2016-05-01

    Specially thick coal seam with complex construction, such as rock parting and alternative soft and hard coal, is called specially thick coal seam with rock parting (STCSRP), which easily leads to rock burst during mining. Based on the stress distribution of rock parting zone, this study investigated the mechanism, engineering discriminant conditions, prevention methods, and risk evaluation method of rock burst occurrence in STCSRP through setting up a mechanical model. The main conclusions of this study are as follows. (1) When the mining face moves closer to the rock parting zone, the original non-uniform stress of the rock parting zone and the advancing stress of the mining face are combined to intensify gradually the shearing action of coal near the mining face. When the shearing action reaches a certain degree, rock burst easily occurs near the mining face. (2) Rock burst occurrence in STCSRP is positively associated with mining depth, advancing stress concentration factor of the mining face, thickness of rock parting, bursting liability of coal, thickness ratio of rock parting to coal seam, and difference of elastic modulus between rock parting and coal, whereas negatively associated with shear strength. (3) Technologies of large-diameter drilling, coal seam water injection, and deep hole blasting can reduce advancing stress concentration factor, thickness of rock parting, and difference of elastic modulus between rock parting and coal to lower the risk of rock burst in STCSRP. (4) The research result was applied to evaluate and control the risk of rock burst occurrence in STCSRP.

  20. Kimberley rock art dating project

    International Nuclear Information System (INIS)

    Walsh, G.L.; Morwood, M.

    1997-01-01

    The art's additional value, unequalled by traditionally recognised artefacts, is its permanent pictorial documentation presenting a 'window' into the otherwise intangible elements of perceptions, vision and mind of pre-historic cultures. Unfortunately it's potential in establishing Kimberley archaeological 'big picture' still remains largely unrecognised. Some of findings of the Kimberley Rock Art Dating Project, using AMS and optical stimulated luminescence (OSL) dating techniques, are outlined. It is estimated that these findings will encourage involvement by a greater diversity of specialist disciplines to tie findings into levels of this art sequence as a primary reference point. The sequence represents a sound basis for selecting specific defined images for targeting detailed studies by a range of dating technique. This effectively removes the undesirable ad hoc sampling of 'apparently old paintings'; a process which must unavoidably remain the case with researchers working on most global bodies of rock art

  1. ESR dating of fault rocks

    International Nuclear Information System (INIS)

    Lee, Hee Kwon

    2002-03-01

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then trow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs grain size shows a plateau for grains below critical size : these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected from the Yangsan fault system. ESR dates from the this fault system range from 870 to 240 ka. Results of this research suggest that long-term cyclic fault activity continued into the pleistocene

  2. Radionuclide fixation mechanisms in rocks

    International Nuclear Information System (INIS)

    Nakashima, S.

    1991-01-01

    In the safety evaluation of the radioactive waste disposal in geological environment, the mass balance equation for radionuclide migration is given. The sorption of radionuclides by geological formations is conventionally represented by the retardation of the radionuclides as compared with water movement. In order to quantify the sorption of radionuclides by rocks and sediments, the distribution ratio is used. In order to study quantitatively the long term behavior of waste radionuclides in geological environment, besides the distribution ratio concept in short term, slower radionuclide retention reaction involving mineral transformation should be considered. The development of microspectroscopic method for long term reaction path modeling, the behavior of iron during granite and water interaction, the reduction precipitation of radionuclides, radionuclide migration pathways, and the representative scheme of radionuclide migration and fixation in rocks are discussed. (K.I.)

  3. ESR dating of fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2002-03-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then trow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs grain size shows a plateau for grains below critical size : these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected from the Yangsan fault system. ESR dates from the this fault system range from 870 to 240 ka. Results of this research suggest that long-term cyclic fault activity continued into the pleistocene.

  4. Relative Permeability of Fractured Rock

    Energy Technology Data Exchange (ETDEWEB)

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  5. The complex systematics of zircons in migmatitic gneisses: An example from an Archean migmatite along the Patos Shear Zone, Borborema Province, NE Brazil

    International Nuclear Information System (INIS)

    Costa, A.C.D; Hackspacher, P.C; Dantas, E.L; Fetter, A.H.

    2001-01-01

    The Northem Tectonic Domain Borborema Province, in Northeast of Brazil records a complex history of tectonic activity ranging from 3.4 Ga to 0.6 Ga (Brito Neves, 1995 and Dantas, 1996). U-Pb systematics of zircons from a migmatitic gneiss just north of the Patos Shear Zone provide an excellent example of the difficulties encountered using conventional single-grain U/Pb zircon geochronology in polydeformed gneiss terranes. Our conventional single grain zircon analyses of a migmatite yielded Archean ages between ca. 3.3 at 2.8 a, as well as some highly discordant Paleoproterozoic ages. Subsequent cathodoluminescence images of these zircon grains showed complex internal structures that possibly record up to 4 separate stages of zircon growth. With such internal complexity, is impossible resolve primary crystallization ages as well as the ages of subsequent overgrowth events using conventional single grain analyses. Such resolution will require analyses of the individual grain domains using the SHRIMP method (au)

  6. Mineral and rock chemistry of Mata da Corda Kamafugitic Rocks (Minas Gerais State, Brazil)

    International Nuclear Information System (INIS)

    Albuquerque Sgarbi, Patricia B. de; Valenca, Joel G.

    1995-01-01

    The volcanic rocks of the Mata da Corda Formation (Upper Cretaceous) in Minas Gerais, Brazil, are mafic potassic to ultra potassic rocks of kamafugitic affinity containing essentially clinopyroxenes, perovskite, magnetite and occasionally olivine, phlogopite, melilite pseudomorphs and apatite. The felsic phases are kalsilite and/or leucite pseudomorphs. The rocks are classified as mafitites, leucitites and kalsilitites. The analysis of the available data of the rocks studied, based on the relevant aspects of the main proposals for the classification of alkaline mafic to ultramafic potassic rocks leads to the conclusion that Sahama's (1974) proposal to divide potassium rich alkaline rocks in two large families is the one to which the Mata da Corda rocks adapt best. According to this and the data in the literature on the mineralogy and mineral and rock chemistries of the other similar occurrences, these rocks may be interpreted as alkaline potassic to ultra potassic rocks of hamafugitic affinity. 11 figs., 5 tabs

  7. ESR dating of fault rocks

    International Nuclear Information System (INIS)

    Lee, Hee Kwon

    2003-02-01

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then grow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs. grain size shows a plateau for grains below critical size; these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected near the Gori nuclear reactor. Most of the ESR signals of fault rocks collected from the basement are saturated. This indicates that the last movement of the faults had occurred before the Quaternary period. However, ESR dates from the Oyong fault zone range from 370 to 310 ka. Results of this research suggest that long-term cyclic fault activity of the Oyong fault zone continued into the Pleistocene

  8. ESR dating of fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2003-02-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then grow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs. grain size shows a plateau for grains below critical size; these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected near the Gori nuclear reactor. Most of the ESR signals of fault rocks collected from the basement are saturated. This indicates that the last movement of the faults had occurred before the Quaternary period. However, ESR dates from the Oyong fault zone range from 370 to 310 ka. Results of this research suggest that long-term cyclic fault activity of the Oyong fault zone continued into the Pleistocene.

  9. Source rock hydrocarbons. Present status

    International Nuclear Information System (INIS)

    Vially, R.; Maisonnier, G.; Rouaud, T.

    2013-01-01

    This report first presents the characteristics of conventional oil and gas system, and the classification of liquid and gaseous non conventional hydrocarbons, with the peculiar case of coal-bed methane. The authors then describe how source rock hydrocarbons are produced: production of shale oils and gases (horizontal drilling, hydraulic fracturing, exploitation) and of coal-bed methane and coal mine methane. In the next part, they address and discuss the environmental impact of source rock hydrocarbon production: installation footprint, water resource management, drilling fluids, fracturing fluids composition, toxicity and recycling, air pollution, induced seismicity, pollutions from other exploitation and production activities. They propose an overview of the exploitation and production of source rock gas, coal-bed gas and other non conventional gases in the world. They describe the current development and discuss their economic impacts: world oil context and trends in the USA, in Canada and other countries, impacts on the North American market, on the world oil industry, on refining industries, on the world oil balance. They analyse the economic impacts of non conventional gases: development potential, stakes for the world gas trade, consequence for gas prices, development opportunities for oil companies and for the transport sector, impact on CO 2 emissions, macro-economic impact in the case of the USA

  10. A Review on the British Rock Music

    OpenAIRE

    Hutapea, Alfian Hadi Pranata

    2011-01-01

    Music has an important role in people’s life. In people’s daily, music is often hearing of course and in people’s customs and traditions music is also be used. Music has many genres, one of them is rock music. Many people like rock music especially youngman because rock music has given a message in a song through enthusiasm expression. Rock music has many subgenres and each of subgenres have a distinctive feature. The developing of rock music is very wide in the world, especially in Great Bri...

  11. The physical principles of rock magnetism

    CERN Document Server

    Stacey, Frank

    1974-01-01

    Developments in Solid Earth Geophysics 5: The Physical Principles of Rock Magnetism explores the physical principles of rock magnetism, with emphasis on the properties of finely divided magnetic materials. It discusses the origin and stability of rock magnetizations, the role of remanent magnetism in interpreting magnetic surveys, magnetic anisotropy as an indicator of rock fabric, and the relationship between piezomagnetic changes and seismic activity. Organized into 13 chapters, this volume discusses the properties of solids, magnetite and hematite grains, and rocks with magnetite grains

  12. Effects of explosions in hard rocks

    International Nuclear Information System (INIS)

    Heuze, F.E.; Walton, O.R.; Maddix, D.M.; Shaffer, R.J.; Butkovich, T.R.

    1993-01-01

    This work relates to explosions in hard rocks (ex: basalt, granite, limestone...). Hard rock masses typically have a blocky structure created by the existence of geologic discontinuities such as bedding contacts, faults, and joints. At very high pressure - hundreds of kilobars and above - these discontinuities do not act separately, and the rock appears to be an equivalent continuous medium. At stress of a few tens of kilobars and below, the geologic discontinuities control the kinematics of the rock masses. Hence, the simulation of rock dynamics, anywhere but in the very-near source region, should account for those kinematics

  13. Lead isotope analyses of standard rock samples

    International Nuclear Information System (INIS)

    Koide, Yoshiyuki; Nakamura, Eizo

    1990-01-01

    New results on lead isotope compositions of standard rock samples and their analytical procedures are reported. Bromide form anion exchange chromatography technique was adopted for the chemical separation lead from rock samples. The lead contamination during whole analytical procedure was low enough to determine lead isotope composition of common natural rocks. Silica-gel activator method was applied for emission of lead ions in the mass spectrometer. Using the data reduction of 'unfractionated ratios', we obtained good reproducibility, precision and accuracy on lead isotope compositions of NBS SRM. Here we present new reliable lead isotope compositions of GSJ standard rock samples and USGS standard rock, BCR-1. (author)

  14. Diffusion in the matrix of granitic rock

    International Nuclear Information System (INIS)

    Birgersson, L.; Neretnieks, I.

    1982-07-01

    A migration experiment in the rock matrix is presented. The experiment has been carried out in undisturbed rock, that is rock under its natural stress environment. Since the experiment was performed at the 360 m-level (in the Stripa mine), the rock had nearly the same conditions as the rock surrounding a nuclear waste storage. The results show that all three tracers (Uranine, Cr-EDTA and I - ) have passed the disturbed zone from the injection hole and migrated into undisturbed rock. At the distance of 11 cm from the injection hole 5-10 percent of the injection concentration was found. The results also indicate that the tracer have passed through fissure filling material. These results indicate that it is possible for tracers (and therefore radionuclides) to migrate from a fissure, through fissure filling material, and into the undisturbed rock matrix. (Authors)

  15. Carbonate rock depositional models: A microfacies approach

    Energy Technology Data Exchange (ETDEWEB)

    Carozzi, A.V.

    1988-01-01

    Carbonate rocks contain more than 50% by weight carbonate minerals such as calcite, dolomite, and siderite. Understanding how these rocks form can lead to more efficient methods of petroleum exploration. Micofacies analysis techniques can be used as a method of predicting models of sedimentation for carbonate rocks. Micofacies in carbonate rocks can be seen clearly only in thin sections under a microscope. This section analysis of carbonate rocks is a tool that can be used to understand depositional environments, diagenetic evolution of carbonate rocks, and the formation of porosity and permeability in carbonate rocks. The use of micofacies analysis techniques is applied to understanding the origin and formation of carbonate ramps, carbonate platforms, and carbonate slopes and basins. This book will be of interest to students and professionals concerned with the disciplines of sedimentary petrology, sedimentology, petroleum geology, and palentology.

  16. U-Pb and Sm-Nd preliminary geochronologic data on the Yaounde series, Cameroon: re-interpretation of the granulitic rocks as the suture of a collision in the ''Centrafrican'' belt

    International Nuclear Information System (INIS)

    Schmus, W.R. Van; Penaye, J.; Toteu, S.F.; Nzenti, J.P.

    1993-01-01

    U-Pb on zircons and Sm-Nd on whole-rock analyses have been applied on the schists, micaschists and granulitic gneisses of the Yaounde series. The results fix the granulitic metamorphism in the Yaounde series at 620±10 Ma and the deposition of the series during the Upper Proterozoic. In addition, another remnant of Lower Proterozoic basement, previously recognized in northern Cameroon, has been identified at Kekem northwest of the Yaounde series. The Yaounde granulitic unit is re-interpreted as the suture of a Pan-African collision between a passive margin (Archean Congo craton and its Birrimian Nyong cover) to the south and an intensive granitized active margin (dismembered eburnian basement and Upper Proterozoic series) to the north. (author). 14 refs., 4 figs

  17. Audio-magnetotelluric investigation of sulfide mineralization in Proterozoic-Archean greenstone belts of Eastern Indian Craton

    Science.gov (United States)

    Singh, Shailendra; Maurya, Ved P.; Singh, Roshan K.; Srivastava, Shalivahan; Tripathi, Anurag; Adhikari, P. K.

    2018-04-01

    Greenstone belts are well known for gold occurrences at different regions of the world. The Dhanjori basin in the eastern Singhbhum region shows major characteristics of a rifted greenstone belt. Initially, we conducted 14 audio-magnetotelluric (AMT) measurements for a profile of ˜ 20 km in the frequency range of 1 kHz to 10 Hz over this rather complex geologic environment covering Dhanjori Volcanics (DhV) and Kolhan Group (KG). Subsequently, gravity and magnetic surveys were also conducted over this AMT profile. The purpose of the survey was to identify and map conductive features and to relate them to metallogeny of the area along with the mapping of the basement of Dhanjori basin. The strike analysis showed N30°W strike for DhV for all the frequencies and for sites over KG domain in the frequency range of 100-10 Hz, but for KG domain, the obtained strike in 1 kHz to 100 Hz is N45°E. As the combination of transverse electric (TE), transverse magnetic (TM) and tipper (Tzy) can recover the electrical signature in complex geological environment, we discuss the conductivity model obtained from TE+TM+Tzy only. The inversion was carried for the regional profile with 14 sites and for 7 sites over KG domain. Conductivity model shows two well resolved conductors, one each in KG and Quartz Pebble Conglomerate Dhanjori (QPCD) domains respectively showing common linked concordant features between these regional and KG profiles. The conductors are interpreted as sulfide mineralization linked with QPCD group of rocks which may host gold. These conductors are also horizontally disposed due to the intrusive younger Mayurbhanj Granite. These intrusives correlate well with the gravity modeling as well. The thickness of the Dhanjori basin at the central is about 3.0 km, similar to that from gravity modeling. The conductivity model also indicates the presence of shallow conductors, but could not be resolved due to lack of high frequency data. However, the results from the close

  18. Strike-slip linked core complexes: A new kinematic model of basement rock exhumation in a crustal-scale fault system

    Science.gov (United States)

    Meyer, Sven Erik; Passchier, Cees; Abu-Alam, Tamer; Stüwe, Kurt

    2014-05-01

    Metamorphic core complexes usually develop as extensional features during continental crustal thinning, such as the Basin and Range and the Aegean Terrane. The Najd fault system in Saudi Arabia is a 2000 km-long and 400 km-wide complex network of crustal-scale strike-slip shear zones in a Neoproterozoic collision zone. Locally, the anastomosing shear zones lead to exhumation of lower crustal segments and represent a new kinematic model for the development of core complexes. We report on two such structures: the Qazaz complex in Saudi Arabia and the Hafafit complex in Egypt. The 15 km-wide Qazaz complex is a triangular dome of gently dipping mylonitic foliations within the 140 km-long sinistral strike-slip Qazaz mylonite zone. The gneissic dome consists of high-grade rocks, surrounded by low-grade metasediments and metavolcanics. The main SE-trending strike-slip Qazaz shear zone splits southwards into two branches around the gneiss dome: the western branch is continuous with the shallow dipping mylonites of the dome core, without overprinting, and changes by more than 90 degrees from a NS-trending strike-slip zone to an EW-trending 40 degree south-dipping detachment that bounds the gneiss dome to the south. The eastern SE-trending sinistral strike-slip shear zone branch is slightly younger and transects the central dome fabrics. The gneiss dome appears to have formed along a jog in the strike-slip shear zone during 40 km of horizontal strike-slip motion, which caused local exhumation of lower crustal rocks by 25 km along the detachment. The eastern shear zone branch formed later during exhumation, transacted the gneiss dome and offset the two parts by another 70 km. The Hafafit core complex in Egypt is of similar shape and size to the Qazaz structure, but forms the northern termination of a sinistral strike-slip zone that is at least 100 km in length. This zone may continue into Saudi Arabia as the Ajjaj shear zone for another 100 km. The NW trending strike slip

  19. Pre-impact tectonothermal evolution of the crystalline basement-derived rocks in the ICDP-USGS Eyreville B core, Chesapeake Bay impact structure

    Science.gov (United States)

    Gibson, R.L.; Townsend, G.N.; Horton, J. Wright; Reimold, W.U.

    2009-01-01

    Pre-impact crystalline rocks of the lowermost 215 m of the Eyreville B drill core from the Chesapeake Bay impact structure consist of a sequence of pelitic mica schists with subsidiary metagraywackes or felsic metavolcanic rocks, amphibolite, and calc-silicate rock that is intruded by muscovite (??biotite, garnet) granite and granite pegmatite. The schists are commonly graphitic and pyritic and locally contain plagioclase porphyroblasts, fi brolitic sillimanite, and garnet that indicate middle- to upper-amphibolite-facies peak metamorphic conditions estimated at ??0.4-0.5 GPa and 600-670 ??C. The schists display an intense, shallowly dipping, S1 composite shear foliation with local micrometer- to decimeter-scale recumbent folds and S-C' shear band structures that formed at high temperatures. Zones of chaotically oriented foliation, resembling breccias but showing no signs of retrogression, are developed locally and are interpreted as shear-disrupted fold hinges. Mineral textural relations in the mica schists indicate that the metamorphic peak was attained during D1. Fabric analysis indicates, however, that subhorizontal shear deformation continued during retrograde cooling, forming mylonite zones in which high-temperature shear fabrics (S-C and S-C') are overprinted by progressively lower- temperature fabrics. Cataclasites and carbonate-cemented breccias in more competent lithologies such as the calc-silicate unit and in the felsic gneiss found as boulders in the overlying impactite succession may refl ect a fi nal pulse of low-temperature cataclastic deformation during D1. These breccias and the shear and mylonitic foliations are cut by smaller, steeply inclined anastomosing fractures with chlorite and calcite infill (interpreted as D2). This D2 event was accompanied by extensive chlorite-sericitecalcite ?? epidote retrogression and appears to predate the impact event. Granite and granite pegmatite veins display local discordance to the S1 foliation, but elsewhere

  20. Hot Dry Rock; Geothermal Energy

    Energy Technology Data Exchange (ETDEWEB)

    None

    1990-01-01

    The commercial utilization of geothermal energy forms the basis of the largest renewable energy industry in the world. More than 5000 Mw of electrical power are currently in production from approximately 210 plants and 10 000 Mw thermal are used in direct use processes. The majority of these systems are located in the well defined geothermal generally associated with crustal plate boundaries or hot spots. The essential requirements of high subsurface temperature with huge volumes of exploitable fluids, coupled to environmental and market factors, limit the choice of suitable sites significantly. The Hot Dry Rock (HDR) concept at any depth originally offered a dream of unlimited expansion for the geothermal industry by relaxing the location constraints by drilling deep enough to reach adequate temperatures. Now, after 20 years intensive work by international teams and expenditures of more than $250 million, it is vital to review the position of HDR in relation to the established geothermal industry. The HDR resource is merely a body of rock at elevated temperatures with insufficient fluids in place to enable the heat to be extracted without the need for injection wells. All of the major field experiments in HDR have shown that the natural fracture systems form the heat transfer surfaces and that it is these fractures that must be for geothermal systems producing from naturally fractured formations provide a basis for directing the forthcoming but, equally, they require accepting significant location constraints on HDR for the time being. This paper presents a model HDR system designed for commercial operations in the UK and uses production data from hydrothermal systems in Japan and the USA to demonstrate the reservoir performance requirements for viable operations. It is shown that these characteristics are not likely to be achieved in host rocks without stimulation processes. However, the long term goal of artificial geothermal systems developed by systematic

  1. Hydraulic testing in crystalline rock

    International Nuclear Information System (INIS)

    Almen, K.E.; Andersson, J.E.; Carlsson, L.; Hansson, K.; Larsson, N.A.

    1986-12-01

    Swedish Geolocical Company (SGAB) conducted and carried out single-hole hydraulic testing in borehole Fi 6 in the Finnsjoen area of central Sweden. The purpose was to make a comprehensive evaluation of different methods applicable in crystalline rocks and to recommend methods for use in current and scheduled investigations in a range of low hydraulic conductivity rocks. A total of eight different methods of testing were compared using the same equipment. This equipment was thoroughly tested as regards the elasticity of the packers and change in volume of the test section. The use of a hydraulically operated down-hole valve enabled all the tests to be conducted. Twelve different 3-m long sections were tested. The hydraulic conductivity calculated ranged from about 5x10 -14 m/s to 1x10 -6 m/s. The methods used were water injection under constant head and then at a constant rate-of-flow, each of which was followed by a pressure fall-off period. Water loss, pressure pulse, slug and drill stem tests were also performed. Interpretation was carried out using standard transient evaluation methods for flow in porous media. The methods used showed themselves to be best suited to specific conductivity ranges. Among the less time-consuming methods, water loss, slug and drill stem tests usually gave somewhat higher hydraulic conductivity values but still comparable to those obtained using the more time-consuming tests. These latter tests, however, provided supplementary information on hydraulic and physical properties and flow conditions, together with hydraulic conductivity values representing a larger volume of rock. (orig./HP)

  2. Big Bang Day : Physics Rocks

    CERN Multimedia

    Brian Cox; John Barrowman; Eddie Izzard

    2008-01-01

    Is particle physics the new rock 'n' roll? The fundamental questions about the nature of the universe that particle physics hopes to answer have attracted the attention of some very high profile and unusual fans. Alan Alda, Ben Miller, Eddie Izzard, Dara O'Briain and John Barrowman all have interests in this branch of physics. Brian Cox - CERN physicist, and former member of 90's band D:Ream, tracks down some very well known celebrity enthusiasts and takes a light-hearted look at why this subject can appeal to all of us.

  3. ROCKS & MINERALS DETERMINATION AND ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20150204 Abaydulla Alimjan(Department of Chemistry and Environmental Sciences,Kashgar Teachers College,Kashgar 844006,China);Cheng Chunying Non-Metallic Element Composition Analysis of Non-Ferrous Metal Ores from Oytagh Town,Xinjiang(Rock and Mineral Analysis,ISSN0254-5357,CN11-2131/TD,33(1),2014,p.44-50,5illus.,4tables,28refs.)Key words:nonferrous metals ore,nonmetals,chemical analysis,thermogravimetric analysis Anions in non-ferrous ore materials

  4. Rock Goes to School on Screen: A Model for Teaching Non-"Learned" Musics Derived from the Films "School of Rock" (2003) and "Rock School" (2005)

    Science.gov (United States)

    Webb, Michael

    2007-01-01

    What can be learned from two films with "rock" and "school" in their titles, about rock in school and about music and schooling more broadly? "School of Rock" (2003), a "family comedy," and "Rock School" (2005), a documentary, provoke a range of questions, ideological and otherwise, surrounding the inclusion of rock in formal instructional…

  5. Lower precambrian of the Keivy Terrane, Northeastern Baltic Shield: A stratigraphic succession or a collage of tectonic sheets?

    Science.gov (United States)

    Balagansky, V. V.; Raevsky, A. B.; Mudruk, S. V.

    2011-03-01

    The Keivy Terrane in the northeastern Baltic Shield appreciably differs from the adjacent tectonic blocks. In the northwestern part of this terrane (the Serpovidny Range), an outlier of Paleoproterozoic supracrustal rocks called the Serpovidny structure is surrounded by Archean (?) Keivy high-alumina paraschists. As follows from structural and magnetic data, the Paleoproterozoic rocks are deformed into a tight sheath fold 8 × 2 km in size at the surface and 5 km in length along the sheath axis. Faults parallel to the boundaries of the layers and locally cutting them off at an acute angle are involved in folding as well. The outer boundaries of the Serpovidny structure are tectonic. This structure is complementary to a larger tectonic lens composed of the Keivy mica schists. It is concluded that all of the supracrustal rocks of the Serpovidny Range are in fact tectonic sheets and lenses deformed into sheath folds. The literature data show that kilometer-scale sheath folds occur throughout the Keivy paraschist belt and most likely were formed owing to thrusting of the Murmansk Craton onto the Keivy Terrane in the south-southwestern direction. Foliation and lineation related to thrusting have been established in the Archean silicic metavolcanics and peralkaline granites occupying the most part of the terrane. In contrast, the granitoids and gabbroanorthosites of the Archean basement, which form a block 90 × 20 km in the southwestern Keivy Terrane, were not affected by Paleoproterozoic deformation. In other words, a detached assembly of tectonic sheets composed of the upper and middle crustal rocks that underwent deformation at the initial stage of the Paleoproterozoic Lapland-Kola Orogeny and the Archean basement, which is free of this deformation, are distinguished. The depth of detachment is estimated at 20-25 km. The detachment of the upper and middle crust in the Keivy Terrane and its position in the structure of the Baltic Shield are consistent with a

  6. Radon exhalation from granitic rocks

    International Nuclear Information System (INIS)

    Del Claro, Flávia; Paschuk, Sergei A.; Corrêa, Janine N.; Mazer, Wellington; Narloch, Danielle Cristine; Martin, Aline Cristina; Denyak, Valeriy

    2017-01-01

    Naturally occurring radionuclides such as radon ( 222 Rn), its decay products and other elements from the radioactive series of uranium ( 238 U and 235 U) and thorium ( 232 Th) are an important source of human exposure to natural radioactivity. The worldwide evaluation of health radiobiological effects and risks from population exposure to natural radionuclides is a growing concern. About 50% of personal radiation annual dose is related to radionuclides such as radon ( 222 Rn), thoron ( 220 Rn), radium ( 226 Ra), thorium ( 232 Th) and potassium ( 40 K), which are present in modern materials commonly used in construction of dwellings and buildings. The radioactivity of marbles and granites is of big concern since under certain conditions the radioactivity levels of these materials can be hazardous to the population and require the implementation of mitigation procedures. Present survey of the 222 Rn and 220 Rn activity concentration liberated in the air was performed using commercialized Brazilian granite rocks at national market as well as exported to other countries. The 222 Rn and 220 Rn measurements were performed using the AlphaGUARD instant monitor and RAD7 detector, respectively. This study was performed at the Applied Nuclear Physics Laboratory of the Federal University of Technology – Paraná (UTFPR). Obtained results of radon concentration activity in air exhaled studied samples of granites varied from 3±1 Bq/m 3 to 2087±19 Bq/m 3 , which shows that some samples of granitic rocks represent rather elevated health risk the population. (author)

  7. Hydraulic gradients in rock aquifers

    International Nuclear Information System (INIS)

    Dahlblom, P.

    1992-05-01

    This report deals with fractured rock as a host for deposits of hazardous waste. In this context the rock, with its fractures containing moving groundwater, is called the geological barrier. The desired properties of the geological barrier are low permeability to water, low hydraulic gradients and ability to retain matter dissolved in the water. The hydraulic gradient together with the permeability and the porosity determines the migration velocity. Mathematical modelling of the migration involves calculation of the water flow and the hydrodynamic dispersion of the contaminant. The porous medium approach can be used to calculate mean flow velocities and hydrodynamic dispersion of a large number of fractures are connected, which means that a large volume have to be considered. It is assumed that the porous medium approach can be applied, and a number of idealized examples are shown. It is assumed that the groundwater table is replenished by percolation at a constant rate. One-dimensional analytical calculations show that zero hydraulic gradients may exist at relatively large distance from the coast. Two-dimensional numerical calculations show that it may be possible to find areas with low hydraulic gradients and flow velocities within blocks surrounded by areas with high hydraulic conductivity. (au)

  8. Laboratory characterization of rock joints

    International Nuclear Information System (INIS)

    Hsiung, S.M.; Kana, D.D.; Ahola, M.P.; Chowdhury, A.H.; Ghosh, A.

    1994-05-01

    A laboratory characterization of the Apache Leap tuff joints under cyclic pseudostatic and dynamic loads has been undertaken to obtain a better understanding of dynamic joint shear behavior and to generate a complete data set that can be used for validation of existing rock-joint models. Study has indicated that available methods for determining joint roughness coefficient (JRC) significantly underestimate the roughness coefficient of the Apache Leap tuff joints, that will lead to an underestimation of the joint shear strength. The results of the direct shear tests have indicated that both under cyclic pseudostatic and dynamic loadings the joint resistance upon reverse shearing is smaller than that of forward shearing and the joint dilation resulting from forward shearing recovers during reverse shearing. Within the range of variation of shearing velocity used in these tests, the shearing velocity effect on rock-joint behavior seems to be minor, and no noticeable effect on the peak joint shear strength and the joint shear strength for the reverse shearing is observed

  9. Aespoe hard rock laboratory Sweden

    International Nuclear Information System (INIS)

    1992-01-01

    The aim of the new Aespoe hard rock laboratory is to demonstrate state of the art of technology and evaluation methods before the start of actual construction work on the planned deep repository for spent nuclear fuel. The nine country OECD/NEA project in the Stripa mine in Sweden has been an excellent example of high quality international research co-operation. In Sweden the new Aespoe hard rock laboratory will gradually take over and finalize this work. SKB very much appreciates the continued international participation in Aespoe which is of great value for the quality efficiency, and confidence in this kind of work. We have invited a number of leading experts to this first international seminar to summarize the current state of a number of key questions. The contributions show the great progress that has taken place during the years. The results show that there is a solid scientific basis for using this knowledge on site specific preparation and work on actual repositories. (au)

  10. Proceedings of the 3. Canada-US rock mechanics symposium and 20. Canadian rock mechanics symposium : rock engineering 2009 : rock engineering in difficult conditions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This conference provided a forum for geologists, mining operators and engineers to discuss the application of rock mechanics in engineering designs. Members of the scientific and engineering communities discussed challenges and interdisciplinary elements involved in rock engineering. New geological models and methods of characterizing rock masses and ground conditions in underground engineering projects were discussed along with excavation and mining methods. Papers presented at the conference discussed the role of rock mechanics in forensic engineering. Geophysics, geomechanics, and risk-based approaches to rock engineering designs were reviewed. Issues related to high pressure and high flow water conditions were discussed, and new rock physics models designed to enhance hydrocarbon recovery were presented. The conference featured 84 presentations, of which 9 have been catalogued separately for inclusion in this database. tabs., figs.

  11. Chemical buffering capacity of clay rock

    International Nuclear Information System (INIS)

    Beaucaire, C.; Pearson, F.J.; Gautschi, A.

    2004-01-01

    The long-term performance of a nuclear waste repository is strongly dependent on the chemical properties of the host rock. The host rock establishes the chemical environment that determines such important performance attributes as radionuclide solubilities from the waste and the transport rates from the repository to the accessible environment. Clay-rich rocks are especially favourable host rocks because they provide a strong buffering capacity to resist chemical changes prompted either internally, by reactions of the waste itself and emplacement materials, or externally, by changes in the hydrologic systems surrounding the host rock. This paper will focus on three aspects of the stability of clay-rich host rocks: their ability to provide pCO 2 and redox buffering, and to resist chemical changes imposed by changes in regional hydrology and hydro-chemistry. (authors)

  12. Single-zircon dating by stepwise Pb-evaporation constrains the Archean history of detrital zircons from the Jack Hills, Western Australia

    International Nuclear Information System (INIS)

    Kober, B.; Lippolt, H.J.; Pidgeon, R.T.

    1989-01-01

    Pb isotope analyses have been carried out on 42 zircon grains from a Western Australian metaconglomerate using stepwise Pb-evaporation directly in the ion source of a thermal ionization mass spectrometer. The metaconglomerate is from the Archean Jack Hills Metasedimentary Belt, and is known from ion microprobe (''SHRIMP'') analyses to contain a complex zircon population with ages between 4.2 Ga and 3.1 Ga. The same complex pattern of ages is found by the Pb evaporation studies. Five grains yielded minimum crystallization ages from 4.17 Ga to 4.07 Ga. The main population appears significantly younger, having been generated at about 3.55-3.3 Ga. The agreement between the two analytical approaches confirms the SHRIMP results and demonstrates the value of the stepwise-evaporation technique in determining the age patterns of mixing zircon populations. In many of the evaporative Pb isotope records the 207/206 ratios remained constant for all evaporation steps, which we interpret as evaporation from concordant zircon phases. However, for the majority of zircons 207/206 ratios increased with increasing evaporation temperature, and usually approached constant values during evaporation at the highest temperatures. This can be attributed to mixing of different radiogenic Pb components from either crystalline zircon phases of different ages or from domains of isotopically disturbed metamict zircon. Present results confirm > 4 Ga zircon ages in the metaconglomerate from the Hack Hills and substantiate formation of crust at a very early stage in the evolution of the earth. Results also confirm a major crust-forming event 3.55-3.3 Ga ago. (orig.)

  13. Panta Rhei - the changing face of rocks (Stephan Mueller Medal Lecture)

    Science.gov (United States)

    Passchier, Cees W.

    2017-04-01

    The Earth's lithosphere changes shape continuously by plate tectonics and other processes but, unfortunately, we cannot directly access the deeper parts of our planet to study this evolution and the active deformation processes involved. Indirect, geophysical observations allow us to reconstruct processes on a larger scale, but the details on a smaller scale must be studied from samples of metamorphic rocks that have travelled to the surface by complex paths, being modified along the way. Structural analysis of metamorphic rocks has helped to unravel deformation mechanisms and the associated geometric, mineralogical and geochemical changes, but even so there remains a lot to be learned: For example, we know little about the formation of porphyroblasts and their relation with the surrounding fabric, or of porphyroclasts, mineral fish, foliations, lineations, flanking structures, strain fringes and other vorticity gauges; likewise, on a larger scale, the development of gneiss domes, and complex ductile shear zones is poorly understood. This may seem a problem for specialists only, but it actually concerns all large-scale tectonic studies, since the geometry of deformation structures is the "tool-box" of tectonic reconstructions. Recent tectonic processes and large-scale changes in the arrangement of lithospheric fragments are relatively well understood, because we can rely on direct observations of current processes. However, the further we go back in time, down to the Archean, the more we rely on incomplete data obtained from metamorphic rocks that have been preserved. In many cases, deformation geometries in rocks are the single witnesses available of ancient tectonic processes and history, and their correct interpretation is therefore of crucial importance. Without a reliable structural geology toolbox, it is not possible to correctly interpret early, especially Precambrian tectonic processes. This will be demonstrated with examples from Namibia and Australia

  14. Radiation transport in statistically inhomogeneous rocks

    International Nuclear Information System (INIS)

    Lukhminskij, B.E.

    1975-01-01

    A study has been made of radiation transfer in statistically inhomogeneous rocks. Account has been taken of the statistical character of rock composition through randomization of density. Formulas are summarized for sigma-distribution, homogeneous density, the Simpson and Cauchy distributions. Consideration is given to the statistics of mean square ranges in a medium, simulated by the jump Markov random function. A quantitative criterion of rock heterogeneity is proposed

  15. Response of rocks to large stresses

    International Nuclear Information System (INIS)

    Schock, R.N.

    1976-01-01

    To predict the dimensions and characteristics of impact- and explosion-induced craters, one must know the equation of state of the rocks in which the crater is formed. Recent experimental data shed light upon inelastic processes that influence the stress/strain behavior of rocks. We examine these data with a view to developing models that could be used in predicting cratering phenomena. New data is presented on the volume behavior of two dissimilar rocks subjected to tensile stresses

  16. Rock breaking methods to replace blasting

    Science.gov (United States)

    Zhou, Huisheng; Xie, Xinghua; Feng, Yuqing

    2018-03-01

    The method of breaking rock by blasting has a high efficiency and the cost is relatively low, but the associated vibration, flyrock, production of toxic gases since the 1970’s, the Western developed countries began to study the safety of breaking rock. This paper introduces different methods and their progress to safely break rock. Ideally, safe rock breaking would have little vibration, no fly stone, and no toxic gases, which can be widely used in municipal engineering, road excavation, high-risk mining, quarrying and complex environment.

  17. Hopi and Anasazi Alignments and Rock Art

    Science.gov (United States)

    Bates, Bryan C.

    The interaction of light and shadow on ancestral Puebloan rock art, or rock art demarcating sunrise/set horizon points that align with culturally significant dates, has long been assumed to be evidence of "intentional construct" for marking time or event by the native creator. However, anthropological rock art research requires the scientific control of cultural time, element orientation and placement, structure, and association with other rock art elements. The evaluation of five exemplars challenges the oft-held assumption that "if the interaction occurs, it therefore supports intentional construct" and thereby conveys meaning to the native culture.

  18. Professional users handbook for rock bolting

    Energy Technology Data Exchange (ETDEWEB)

    Stillborg, B.

    1986-01-01

    The paper is a practical handbook which reviews the basic principles of rock bolting and sets out the design considerations used for most types of rockbolts in current use. It discusses the characteristics of these bolts and gives information on installation procedures and the observations and measurement of rockbolt performance. Rockbolting is considered under the following chapter headings: review of typical rockbolt systems; rockbolt installation; testing of rockbolts; design considerations; design of rock reinforcement; monitoring; cost of rock bolting; and Atlas Lopco auxillary equipment for rock bolting. 45 refs.

  19. Tunnel Design by Rock Mass Classifications

    Science.gov (United States)

    1990-01-01

    Engineering," revised second edition, Institution of Mining and Metallurgy, London, 1977, pp 113-115 and 150-192. 42. Selmer - Olsen , R., and Broch, E...to wall when a)/03 > 10, re- stability) ................ 10-5 0.66-0.33 0.5-2.0 duce oc and ot to L. Mild rock burst (massive 0.6 cc and 0.6 on rock ...5-2.5 0.33-0.16 5-10 where: 0 c = uncon-fined compression M. Heavy rock burst (massive strength, at = rock

  20. Igneous rocks formed by hypervelocity impact

    Science.gov (United States)

    Osinski, Gordon R.; Grieve, Richard A. F.; Bleacher, Jacob E.; Neish, Catherine D.; Pilles, Eric A.; Tornabene, Livio L.

    2018-03-01

    Igneous rocks are the primary building blocks of planetary crusts. Most igneous rocks originate via decompression melting and/or wet melting of protolith lithologies within planetary interiors and their classification and compositional, petrographic, and textural characteristics, are well-studied. As our exploration of the Solar System continues, so too does the inventory of intrusive and extrusive igneous rocks, settings, and processes. The results of planetary exploration have also clearly demonstrated that impact cratering is a ubiquitous geological process that has affected, and will continue to affect, all planetary objects with a solid surface, whether that be rock or ice. It is now recognized that the production of igneous rocks is a fundamental outcome of hypervelocity impact. The goal of this review is to provide an up-to-date synthesis of our knowledge and understanding of igneous rocks formed by hypervelocity impact. Following a brief overview of the basics of the impact process, we describe how and why melts are generated during impact events and how impact melting differs from endogenic igneous processes. While the process may differ, we show that the products of hypervelocity impact can share close similarities with volcanic and shallow intrusive igneous rocks of endogenic origin. Such impact melt rocks, as they are termed, can display lobate margins and cooling cracks, columnar joints and at the hand specimen and microscopic scale, such rocks can display mineral textures that are typical of volcanic rocks, such as quench crystallites, ophitic, porphyritic, as well as features such as vesicles, flow textures, and so on. Historically, these similarities led to the misidentification of some igneous rocks now known to be impact melt rocks as being of endogenic origin. This raises the question as to how to distinguish between an impact versus an endogenic origin for igneous-like rocks on other planetary bodies where fieldwork and sample analysis may not

  1. Regulation of ROCK Activity in Cancer

    Science.gov (United States)

    Morgan-Fisher, Marie; Wewer, Ulla M.

    2013-01-01

    Cancer-associated changes in cellular behavior, such as modified cell-cell contact, increased migratory potential, and generation of cellular force, all require alteration of the cytoskeleton. Two homologous mammalian serine/threonine kinases, Rho-associated protein kinases (ROCK I and II), are key regulators of the actin cytoskeleton acting downstream of the small GTPase Rho. ROCK is associated with cancer progression, and ROCK protein expression is elevated in several types of cancer. ROCKs exist in a closed, inactive conformation under quiescent conditions, which is changed to an open, active conformation by the direct binding of guanosine triphosphate (GTP)–loaded Rho. In recent years, a number of ROCK isoform-specific binding partners have been found to modulate the kinase activity through direct interactions with the catalytic domain or via altered cellular localization of the kinases. Thus, these findings demonstrate additional modes to regulate ROCK activity. This review describes the molecular mechanisms of ROCK activity regulation in cancer, with emphasis on ROCK isoform-specific regulation and interaction partners, and discusses the potential of ROCKs as therapeutic targets in cancer. PMID:23204112

  2. Remarks on some rock neutron parameters

    International Nuclear Information System (INIS)

    Czubek, J.A.

    1983-01-01

    A method to calculate the thermal neutron parameters (absorption cross-section, diffusion coefficient and diffusion length) of rocks is given. It is based on a proper energy averaging of cross-sections for all rock matrix and rock saturating liquid constituents. Special emphasis is given to the presence of hydrogen. The diffusion lengths in different lithologies in the function of the variable rock porosity have been calculated. An influence of the thermal neutron spectrum on the shape of the porosity calibration curves for the dual spacing neutron method is shown. This influence has been estimated on two porosity units, on average. (author)

  3. Sorption of radionuclides on hard rocks

    International Nuclear Information System (INIS)

    Berry, J.A.; Bourke, P.J.; Green, A.; Littleboy, A.K.

    1987-09-01

    Methods for measuring sorption on hard rocks, particularly of strontium, caesium, neptunium and americium on Darley Dale sandstone and Welsh slate have been investigated. The methods tried included batch tests with crushed rock and tests of simultaneous diffusion and convection with sorption on intact rock. High pressures (800m H 2 O) were used in the convective tests to pump water quickly through the rock samples and to measure high sorptivities in times shorter than those needed in the diffusive methods with intact samples. (author)

  4. Provenance and tectonic setting of siliciclastic rocks associated with the Neoproterozoic Dahongliutan BIF: Implications for the Precambrian crustal evolution of the Western Kunlun orogenic belt, NW China

    Science.gov (United States)

    Hu, Jun; Wang, He; Wang, Min

    2017-10-01

    The Late Neoproterozoic Dahongliutan BIF is associated with siliciclastic rocks in the Tianshuihai terrane of the Western Kunlun orogenic belt (WKO), NW China. The sedimentary rocks have various weathering indices (e.g., CIA = 57-87, PIA = 61-96 and Th/U = 4.85-12.45), indicative of varying degrees of weathering in the source area. The rocks have trace element ratios, such as Th/Sc = 0.60-1.21 and Co/Th = 0.29-1.67, and light rare earth element (LREE) enriched chondrite-normalized REE patterns, suggesting that they were mainly sourced from intermediate and felsic rocks. Available U-Pb ages of detrital zircon from these rocks reveal that the detrital sources may have been igneous and metamorphic rocks from the WKO and the Tarim Block. Our study suggests that the Dahongliutan BIF and hosting siliciclastic rocks may have deposited in a setting transitional from a passive to active continental margin, probably related to the Late Neoproterozoic-Early Cambrian seafloor spreading and subduction of the Proto-Tethys Ocean. U-Pb dating of 163 detrital zircons defines five major age populations at 2561-2329 Ma, 2076-1644 Ma, 1164-899 Ma, 869-722 Ma and 696-593 Ma. These age groups broadly correspond to the major stages of supercontinent assembly and breakup events widely accepted for Columbia, Rodinia and Gondwana. Some zircons have TDM2 model ages of 3.9-1.8 Ga and negative εHf(t) values, suggesting that the Archean to Paleoproterozoic (as old as Eoarchean) crustal materials were episodically reworked and incorporated into the late magmatic process in the WKO. Some Neoproterozoic zircons have TDM2 model ages of 1.47-1.07 Ga and 1.81-1.53 Ga and positive εHf(t) values, indicating juvenile crustal growth during the Mesoproterozoic. Our new results, combined with published data, imply that both the Tianshuihai terrane in the WKO and the Tarim Block share the same Precambrian tectonic evolution history.

  5. Hydrogeomechanics for rock engineering: coupling subsurface hydrogeomechanical assessement and hydrogeotechnical mapping on fracturated rock masses

    OpenAIRE

    Meirinhos, João Miguel de Freitas

    2015-01-01

    The present work aims to achieve and further develop a hydrogeomechanical approach in Caldas da Cavaca hydromineral system rock mass (Aguiar da Beira, NW Portugal), and contribute to a better understanding of the hydrogeological conceptual site model. A collection of several data, namely geology, hydrogeology, rock and soil geotechnics, borehole hydraulics and hydrogeomechanics, was retrieved from three rock slopes (Lagoa, Amores and Cancela). To accomplish a comprehensive analysis and rock e...

  6. Abiogenic methanogenesis in crystalline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lollar, B.S.; Frape, S.K. (Univ. of Waterloo, Ontario (Canada)); Weise, S.M. (Institut fuer Hydrologie (G.S.F), Neuherberg (Germany)); Fritz, P. (UFZ, Umweltforschungszentrum, Leipzig-Halle (Germany)); Macko, S.A. (Univ. of Virginia, Charlottesville, VA (United States)); Welhan, J.A. (Idaho State Univ., Pacatello, ID (United States))

    1993-12-01

    Isotopically anomalous CH[sub 4]-rich gas deposits are found in mining sites on both the Canadian and Fennoscandian shields. With [delta][sup 13]C[sub CH4] values from -22.4 to -48.5% and [delta]D[sub CH4] values from -133 to -372%, these methane deposits cannot be accounted for by conventional processes for bacterial or thermogenic methanogenesis. Compositionally the gases are similar to other CH[sub 4]-rich gas occurrences found in Canadian and Fennoscandian shield rocks. However, the isotopically anomalous gases of this study are characterized by unexpectedly high concentrations of H[sub 2] gas, ranging from several volume percent up to 30 vol%. The H[sub 2] gases are consistently depleted in the heavy isotope, with [delta]D[sub H[sub 2

  7. An investigation of rock fall and pore water pressure using LIDAR in Highway 63 rock cuts.

    Science.gov (United States)

    2014-07-01

    The purpose of this research work is compare LIDAR scanning measurements of rock fall with the natural changes in groundwater level to determining the effect of water pressures (levels) on rock fall. To collect the information of rock cut volume chan...

  8. Computational Models of Rock Failure

    Science.gov (United States)

    May, Dave A.; Spiegelman, Marc

    2017-04-01

    Practitioners in computational geodynamics, as per many other branches of applied science, typically do not analyse the underlying PDE's being solved in order to establish the existence or uniqueness of solutions. Rather, such proofs are left to the mathematicians, and all too frequently these results lag far behind (in time) the applied research being conducted, are often unintelligible to the non-specialist, are buried in journals applied scientists simply do not read, or simply have not been proven. As practitioners, we are by definition pragmatic. Thus, rather than first analysing our PDE's, we first attempt to find approximate solutions by throwing all our computational methods and machinery at the given problem and hoping for the best. Typically this approach leads to a satisfactory outcome. Usually it is only if the numerical solutions "look odd" that we start delving deeper into the math. In this presentation I summarise our findings in relation to using pressure dependent (Drucker-Prager type) flow laws in a simplified model of continental extension in which the material is assumed to be an incompressible, highly viscous fluid. Such assumptions represent the current mainstream adopted in computational studies of mantle and lithosphere deformation within our community. In short, we conclude that for the parameter range of cohesion and friction angle relevant to studying rocks, the incompressibility constraint combined with a Drucker-Prager flow law can result in problems which have no solution. This is proven by a 1D analytic model and convincingly demonstrated by 2D numerical simulations. To date, we do not have a robust "fix" for this fundamental problem. The intent of this submission is to highlight the importance of simple analytic models, highlight some of the dangers / risks of interpreting numerical solutions without understanding the properties of the PDE we solved, and lastly to stimulate discussions to develop an improved computational model of

  9. Hydraulic conductivity of rock fractures

    International Nuclear Information System (INIS)

    Zimmerman, R.W.; Bodvarsson, G.S.

    1994-10-01

    Yucca Mountain, Nevada contains numerous geological units that are highly fractured. A clear understanding of the hydraulic conductivity of fractures has been identified as an important scientific problem that must be addressed during the site characterization process. The problem of the flow of a single-phase fluid through a rough-walled rock fracture is discussed within the context of rigorous fluid mechanics. The derivation of the cubic law is given as the solution to the Navier-Stokes equations for flow between smooth, parallel plates, the only fracture geometry that is amenable to exact treatment. The various geometric and kinetic conditions that are necessary in order for the Navier-Stokes equations to be replaced by the more tractable lubrication or Hele-Shaw equations are studied and quantified. Various analytical and numerical results are reviewed pertaining to the problem of relating the effective hydraulic aperture to the statistics of the aperture distribution. These studies all lead to the conclusion that the effective hydraulic aperture is always less than the mean aperture, by a factor that depends on the ratio of the mean value of the aperture to its standard deviation. The tortuosity effect caused by regions where the rock walls are in contact with each other is studied using the Hele-Shaw equations, leading to a simple correction factor that depends on the area fraction occupied by the contact regions. Finally, the predicted hydraulic apertures are compared to measured values for eight data sets from the literature for which aperture and conductivity data were available on the same fracture. It is found that reasonably accurate predictions of hydraulic conductivity can be made based solely on the first two moments of the aperture distribution function, and the proportion of contact area. 68 refs

  10. Radon exhalation from granitic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Del Claro, Flávia; Paschuk, Sergei A.; Corrêa, Janine N.; Mazer, Wellington; Narloch, Danielle Cristine; Martin, Aline Cristina [Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba, PR (Brazil); Denyak, Valeriy, E-mail: flaviadelclaro@gmail.com, E-mail: spaschuk@gmail.com, E-mail: janine_nicolosi@hotmail.com, E-mail: denyak@gmail.com [Instituto de Pesquisa Pelé Pequeno Príncipe (IPPP), Curitiba, PR (Brazil)

    2017-07-01

    Naturally occurring radionuclides such as radon ({sup 222}Rn), its decay products and other elements from the radioactive series of uranium ({sup 238}U and {sup 235}U) and thorium ({sup 232}Th) are an important source of human exposure to natural radioactivity. The worldwide evaluation of health radiobiological effects and risks from population exposure to natural radionuclides is a growing concern. About 50% of personal radiation annual dose is related to radionuclides such as radon ({sup 222}Rn), thoron ({sup 220}Rn), radium ({sup 226}Ra), thorium ({sup 232}Th) and potassium ({sup 40}K), which are present in modern materials commonly used in construction of dwellings and buildings. The radioactivity of marbles and granites is of big concern since under certain conditions the radioactivity levels of these materials can be hazardous to the population and require the implementation of mitigation procedures. Present survey of the {sup 222}Rn and {sup 220}Rn activity concentration liberated in the air was performed using commercialized Brazilian granite rocks at national market as well as exported to other countries. The {sup 222}Rn and {sup 220}Rn measurements were performed using the AlphaGUARD instant monitor and RAD7 detector, respectively. This study was performed at the Applied Nuclear Physics Laboratory of the Federal University of Technology – Paraná (UTFPR). Obtained results of radon concentration activity in air exhaled studied samples of granites varied from 3±1 Bq/m{sup 3} to 2087±19 Bq/m{sup 3}, which shows that some samples of granitic rocks represent rather elevated health risk the population. (author)

  11. The History of Rock Art Research

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. The History of Rock Art Research. Rock art in South India was discovered as early as 1891.The earliest discovery of petroglyphs on the Koppagallu hill in Bellary district was made by Fred Fawcett (1892) who with the assistance of H.T.Knox and Robert Sewell ...

  12. Using Rock Music To Teach History.

    Science.gov (United States)

    Hoffman, Paul Dennis

    1985-01-01

    A secondary history teacher describes how he uses rock and roll music to help students study and interpret modern American history. Besides being a lot of fun to teach, a rock unit makes students realize that even contemporary music has a place in history. (RM)

  13. A guide for rock identification. 4. ed.

    International Nuclear Information System (INIS)

    Pape, H.

    1981-01-01

    The book is based on a practical course for students of geology, mineralogy, geography, and constructional engineering. It will also help interested laymen to identify rocks. Tables are presented which guide the reader in his analysis, so that he will quickly arrive at the name of a rock, the group to which it belongs, and some information on its characteristics and origin. (orig.) [de

  14. Rock Cycle. K-6 Science Curriculum.

    Science.gov (United States)

    Blueford, J. R.; And Others

    Rock Cycle is one of the units of a K-6 unified science curriculum program. The unit consists of four organizing sub-themes: (1) chemistry (introducing the topics of matter, elements, compounds, and chemical bonding); (2) characteristics (presenting hands-on activities with rocks and minerals); (3) minerals (emphasizing the aesthetic and economic…

  15. Phosphine from rocks: mechanically driven phosphate reduction?

    Science.gov (United States)

    Glindemann, Dietmar; Edwards, Marc; Morgenstern, Peter

    2005-11-01

    Natural rock and mineral samples released trace amounts of phosphine during dissolution in mineral acid. An order of magnitude more phosphine (average 1982 ng PH3 kg rock and maximum 6673 ng PH3/kg rock) is released from pulverized rock samples (basalt, gneiss, granite, clay, quartzitic pebbles, or marble). Phosphine was correlated to hardness and mechanical pulverization energy of the rocks. The yield of PH3 ranged from 0 to 0.01% of the total P content of the dissolved rock. Strong circumstantial evidence was gathered for reduction of phosphate in the rock via mechanochemical or "tribochemical" weathering at quartz and calcite/marble inclusions. Artificial reproduction of this mechanism by rubbing quartz rods coated with apatite-phosphate to the point of visible triboluminescence, led to detection of more than 70 000 ng/kg PH3 in the apatite. This reaction pathway may be considered a mechano-chemical analogue of phosphate reduction from lightning or electrical discharges and may contribute to phosphine production via tectonic forces and processing of rocks.

  16. Cenozoic volcanic rocks of Saudi Arabia

    Science.gov (United States)

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

    2016-01-01

    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.

  17. Sorption of cesium in intact rock

    International Nuclear Information System (INIS)

    Puukko, E.

    2014-04-01

    The mass distribution coefficient K d is used in performance assessment (PA) to describe sorption of a radionuclide on rock. The R d is determined using crushed rock which causes uncertainty in converting the R d values to K d values for intact rock. This work describes a method to determine the equilibrium of sorption on intact rock. The rock types of the planned Olkiluoto waste disposal site were T-series mica gneiss (T-MGN), T-series tonalite granodiorite granite gneiss (T-TGG), P-series tonalite granodiorite granite gneiss (P-TGG) and pegmatitic granite (PGR). These rocks contain different amount of biotite which is the main sorbing mineral. The sorption of cesium on intact rock slices was studied by applying an electrical field to speed up migration of cesium into the rock. Cesium is in the solution as a noncomplex cation Cs + and it is sorbed by ion exchange. The tracer used in the experiments was 134 Cs. The experimental sorption on the intact rock is compared with values calculated using the in house cation exchange sorption model (HYRL model) in PHREEQC program. The observed sorption on T-MGN and T-TGG rocks was close to the calculated values. Two PGR samples were from a depth of 70 m and three samples were from a depth of 150 m. Cesium sorbed more than predicted on the two 70 m PGR samples. The sorption of Cs on the three 150 m PGR samples was small which was consistent with the calculations. The pegmatitic granite PGR has the smallest content of biotite of the four rock types. In the case of P-TGG rock the observed values of sorption were only half of the calculated values. Two kind of slices were cut from P-TGG drill core. The slices were against and to the direction of the foliation of the biotite rims. The sorption of cesium on P-TGG rock was same in both cases. The results indicated that there was no effect of the directions of the electric field and the foliation of biotite in the P-TGG rock. (orig.)

  18. Finding the right rocks on Mars

    Science.gov (United States)

    Hargraves, R. B.; Knudsen, J. M.; Madsen, M. B.; Bertelsen, P.

    Locating a rock on the surface of Mars that bears unambiguous evidence of the existence—prior or present—of life on that planet is, understandably, the “Holy Grail” of NASAs sample return missions. Remote recognition of such a rock on Mars will not be easy. We do know, however, that present in the Martian crust—especially in the “Southern highlands”—is rock carrying strong natural remanent magnetization (NRM). Characterization of such magnetized rock has profound implications for adding to our knowledge about the origin and early evolution of the Martian interior, lithosphere, atmosphere, and possibly even Martian life forms [Ward and Brownlee, 2000]. Moreover, it should be possible to recognize such rocks by use of a simple magnetic compass mounted on a Rover.

  19. First Grinding of a Rock on Mars

    Science.gov (United States)

    2004-01-01

    The round, shallow depression in this image resulted from history's first grinding of a rock on Mars. The rock abrasion tool on NASA's Spirit rover ground off the surface of a patch 45.5 millimeters (1.8 inches) in diameter on a rock called Adirondack during Spirit's 34th sol on Mars, Feb. 6, 2004. The hole is 2.65 millimeters (0.1 inch) deep, exposing fresh interior material of the rock for close inspection with the rover's microscopic imager and two spectrometers on the robotic arm. This image was taken by Spirit's panoramic camera, providing a quick visual check of the success of the grinding. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

  20. Disc cutter wear and rock texture in hard rock TBM tunneling

    International Nuclear Information System (INIS)

    Koizumi, Yu; Tsusaka, Kimikazu; Tanimoto, Chikaosa; Nakagawa, Shigeo; Fujita, Naoya

    2008-01-01

    Disc cutter wear in TBM tunneling is caused by initial fragmentation of a solid rock face (the primary fragmentation) and fragmentation of residual rock pieces between a cutterhead and the face (the secondary fragmentation). In two projects through sedimentary and granitic rocks, the authors investigated the relationships between the rate of cutter wear caused by the primary fragmentation, point load index and the grain size and contents of abrasive minerals. As a result, it was found that the tensile strength and the mineral contents of rocks significantly influenced the cutter wear in both projects and thus it is necessary to take into account of rock type. (author)

  1. Preliminary report on the geology and gold mineralization of the South Pass granite-greenstone terrain, Wind River Mountains, western Wyoming (US)

    Science.gov (United States)

    Hausel, W. D.

    1986-01-01

    The South Pass granite-greenstone terrain lies near the southern tip of the Wind River Mountains of western Wyoming. This Archean supracrustal pile has been Wyoming's most prolific source of gold and iron ore. From 1962 to 1983, more than 90 million tons of iron ore were recovered from oxide-facies banded iron formation, and an estimated 325,000 ounces of gold were mined from metagreywacke-hosted shears and associated placers. Precambrian rocks at South Pass are unconformably overlain by Paleozoic sediments along the northeast flank, and a Tertiary pediment buries Archean supracrustals on the west and south. To the northwest, the supracrustals terminate against granodiorite of the Louis Lake batholith; to the east, the supracrustals terminate against granite of the Granite Mountains batholith. The Louis Lake granodiorite is approximately 2,630 + or - 20 m.y. old, and the Granite Mountains granite averages 2,600 m.y. old. The geometry of the greenstone belt is best expressed as a synform that has been modified by complex faulting and folding. Metamorphism is amphibolite grade surrounding a small island of greenschist facies rocks. The younger of the Archean supracrustal successions is the Miners Delight Formation. This unit yielded a Rb-Sr isochron of 2,800 m.y. A sample of galena from the Snowbird Mine within the Miners Delight Formation yielded a model age averaging 2,750 m.y. The Snowbird mineralization appears to be syngenetic and is hosted by metavolcanics of calc-alkaline affinity. Discussion follows.

  2. Fragment Size Distribution of Blasted Rock Mass

    Science.gov (United States)

    Jug, Jasmin; Strelec, Stjepan; Gazdek, Mario; Kavur, Boris

    2017-12-01

    Rock mass is a heterogeneous material, and the heterogeneity of rock causes sizes distribution of fragmented rocks in blasting. Prediction of blasted rock mass fragmentation has a significant role in the overall economics of opencast mines. Blasting as primary fragmentation can significantly decrease the cost of loading, transport, crushing and milling operations. Blast fragmentation chiefly depends on the specific blast design (geometry of blast holes drilling, the quantity and class of explosive, the blasting form, the timing and partition, etc.) and on the properties of the rock mass (including the uniaxial compressive strength, the rock mass elastic Young modulus, the rock discontinuity characteristics and the rock density). Prediction and processing of blasting results researchers can accomplish by a variety of existing software’s and models, one of them is the Kuz-Ram model, which is possibly the most widely used approach to estimating fragmentation from blasting. This paper shows the estimation of fragmentation using the "SB" program, which was created by the authors. Mentioned program includes the Kuz-Ram model. Models of fragmentation are confirmed and calibrated by comparing the estimated fragmentation with actual post-blast fragmentation from image processing techniques. In this study, the Kuz-Ram fragmentation model has been used for an open-pit limestone quarry in Dalmatia, southern Croatia. The resulting calibrated value of the rock factor enables the quality prognosis of fragmentation in further blasting works, with changed drilling geometry and blast design parameters. It also facilitates simulation in the program to optimize blasting works and get the desired fragmentations of the blasted rock mass.

  3. Permanganate diffusion and reaction in sedimentary rocks.

    Science.gov (United States)

    Huang, Qiuyuan; Dong, Hailiang; Towne, Rachael M; Fischer, Timothy B; Schaefer, Charles E

    2014-04-01

    In situ chemical oxidation using permanganate has frequently been used to treat chlorinated solvents in fractured bedrock aquifers. However, in systems where matrix back-diffusion is an important process, the ability of the oxidant to migrate and treat target contaminants within the rock matrix will likely determine the overall effectiveness of this remedial approach. In this study, a series of diffusion experiments were performed to measure the permanganate diffusion and reaction in four different types of sedimentary rocks (dark gray mudstone, light gray mudstone, red sandstone, and tan sandstone). Results showed that, within the experimental time frame (~2 months), oxidant migration into the rock was limited to distances less than 500 μm. The observed diffusivities for permanganate into the rock matrices ranged from 5.3 × 10(-13) to 1.3 × 10(-11) cm(2)/s. These values were reasonably predicted by accounting for both the rock oxidant demand and the effective diffusivity of the rock. Various Mn minerals formed as surface coatings from reduction of permanganate coupled with oxidation of total organic carbon (TOC), and the nature of the formed Mn minerals was dependent upon the rock type. Post-treatment tracer testing showed that these Mn mineral coatings had a negligible impact on diffusion through the rock. Overall, our results showed that the extent of permanganate diffusion and reaction depended on rock properties, including porosity, mineralogy, and organic carbon. These results have important implications for our understanding of long-term organic contaminant remediation in sedimentary rocks using permanganate. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Measurements of thermal properties of rocks

    International Nuclear Information System (INIS)

    Kumada, Toshiaki

    2001-02-01

    The report concerns the measurement of thermal conductivity and specific heat of supplied sedimental rock B and Funyu rock. The method of measurement of these properties was done with the method which was developed at 1997 and improved much in its accuracy by the present author et al. The porosity of sedimental rock B is 0.55, which is deduced from the density of rock (the porosity deduced from the difference between dry and water filled conditions is 0.42) and the shape and size of pores in rock are much different. Its thermal conductivity is 0.238 W/mK in dry and 1.152 W/mK in water filled conditions respectively, while the thermal conductivity of bentonite is 0.238 W/mK in dry and 1.152 W/mK in water saturated conditions. The difference of thermal conductivity between dry and water saturated conditions is little difference in sedimental rock B and bentonite at same porosity. The porosity of Funyu rock is 0.26 and the shape and size of pores in the rock are uniform. Its thermal conductivity is 0.914 W/mK in dry and 1.405 W/mK in water saturated conditions, while the thermal conductivity of bentonite is 0.606 W/mK in dry and 1.591 W/mK in water saturated conditions respectively. The correlation estimating thermal conductivity of rocks was derived based on Fricke correlation by presuming rocks as a suspension. (author)

  5. SHRIMP U-Pb zircon dating of Archean core complex formatio and pancratonic strike-slip deformation in the East Pilbara Granite-Greenstone Terrain

    NARCIS (Netherlands)

    Zegers, T.E.; Nelson, D.R.; Wijbrans, J.R.; White, S.H.

    2001-01-01

    Sensitive high-resolution ion microprobe (SHRIMP) U-Pb dating of zircons from granitic rocks in the East Pilbara Granite-Greenstone Terrain has provided time constraints for main tectonic events in the Shaw Granitoid Complex and has shown that deformation was intricately related to granitoid

  6. Contributions to the petrography, geochemistry and geochronology (U-Pb and Sm-Nd) of the Paleoproterozoic effusive rocks from Iricoume Group, Amazonian Craton, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Suelen Nonata de Souza; Nascimento, Rielva Solimairy Campelo do, E-mail: suelen-marques@hotmail.com, E-mail: rielva@ufam.edu.br [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil). Inst. de Geociencias; Souza, Valmir da Silva; Dantas, Elton Luiz, E-mail: vsouza@unb.br, E-mail: elton@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Inst. de Geociencias; Valerio, Cristovao da Silva, E-mail: cristovao@igeo.ufrr.br [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil). Inst. de Geociencias

    2014-07-01

    The southernmost region of the Guyana shield, Amazonian craton, hosts large record of Paleoproterozoic effusive rocks of the Iricoume Group. They present remarkably well-preserved igneous textures and structures. The SiO{sub 2} contents reveal a bimodal association marked by a compositional gap between acid (SiO{sub 2} > 67 wt%) and intermediate (SiO{sub 2} < 57.7 wt%) rocks. The acid effusive rocks are rhyolites to rhyodacites with high SiO{sub 2}, alkali, Rb, Zr, Nb + Ta, La + Ce and 104 Ga/Al content and low Fe{sub 2}O{sub 3tot}, TiO{sub 2}, CaO, Sr and Co content. They exhibit subalkaline, metaluminous-to-peraluminous compositions, and geochemically compatible to A-type magmatism emplaced in post-collisional to within-plate tectonic settings. The intermediate rocks are andesitic/basalt to andesite relatively high contents of TiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3total}, MgO, CaO, Sr and Co; low SiO{sub 2}, K{sub 2}O, Rb, Zr, Nb + Ta, La + Ce. They have subalkaline and metaluminous geochemical composition and plot on within-plate basalt field. The acid rocks crystallized at 1882 ± 11 Ma in U-Pb analyses for LA-MC-ICPMS zircon data. The Sm-Nd isotopic data on all rocks reveal a Nd TDM model ages between 2.59 and 2.16 Ga and ε{sub Nd}(t) values between -5.78 and 0.03, indicate that the magmatic evolution was related to the reworking of older Paleoproterozoic at the Rhyacian-Siderian period, continental crust (Transamazonian crust-forming event) with some mixing with a limited amount mantle-derived magmas or with contamination by Archean crust. The petrographic, geochemical and geochronological data presented in this paper suggest a within-plate to post-collisional tectonic setting for the Iricoume volcanism, involving lower crust uplift and generation of basalt magma in an extensional regime. (author)

  7. Rock stars for the day

    CERN Multimedia

    Stefania Pandolfi

    2015-01-01

    After a two-year hiatus, the CERN Hardronic Festival is back! On 8 August, ten CERN MusiClub bands will take to the stage for the popular event. As usual, the non-stop show will take place on the terrace of Restaurant 3 and will run until after midnight.   The Canettes Blues Band, part of the CERN MusiClub, performing live on the Music In The Park stage at the Montreux Jazz Festival, on 18 July 2013. A large range of musical styles will entertain the audience: from Irish folk, via 70s/80s/90s rock, to pop, blues and R&B. Alongside the music there will be activities for kids and food and drink stands. This year, the income from food sales will be donated to charity. The spirit that has characterised the festival ever since the first event in 1989 is that of a staff party. Any band who volunteers to play also helps to organise the event and set up the stage. “This is a really good thing because a festival that has been growing for many years requires a considerable amount of har...

  8. Tracer transport in fractured rocks

    International Nuclear Information System (INIS)

    Tsang, C.F.; Tsang, Y.W.; Hale, F.V.

    1988-07-01

    Recent interest in the safety of toxic waste underground disposal and nuclear waste geologic repositories has motivated many studies of tracer transport in fractured media. Fractures occur in most geologic formations and introduce a high degree of heterogeneity. Within each fracture, the aperture is not constant in value but strongly varying. Thus for such media, tracer tends to flow through preferred flowpaths or channels within the fractures. Along each of these channels, the aperture is also strongly varying. A detailed analysis is carried out on a 2D single fracture with variable apertures and the flow through channels is demonstrated. The channels defined this way are not rigidly set pathways for tracer transport, but are the preferred flow paths in the sense of stream-tubes in the potential theory. It is shown that such variable-aperture channels can be characterized by an aperture probability distribution function, and not by the exact deterministic geometric locations. We also demonstrate that the 2D tracer transport in a fracture can be calculated by a model of a system of 1D channels characterized by this distribution function only. Due to the channeling character of tracer transport in fractured rock, random point measurements of tracer breakthrough curves may give results with a wide spread in value due to statistical fluctuations. The present paper suggests that such a wide spread can probably be greatly reduced by making line/areal (or multiple) measurements covering a few spatial correlation lengths. 13 refs., 11 figs., 1 tab

  9. Rock cavern storage of spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Won Jin; Kim, Kyung Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kwon, Sang Ki [Inha University, Incheon (Korea, Republic of)

    2015-12-15

    The rock cavern storage for spent fuel has been assessed to apply in Korea with reviewing the state of the art of the technologies for surface storage and rock cavern storage of spent fuel. The technical feasibility and economic aspects of the rock cavern storage of spent fuel were also analyzed. A considerable area of flat land isolated from the exterior are needed to meet the requirement for the site of the surface storage facilities. It may, however, not be easy to secure such areas in the mountainous region of Korea. Instead, the spent fuel storage facilities constructed in the rock cavern moderate their demands for the suitable site. As a result, the rock cavern storage is a promising alternative for the storage of spent fuel in the aspect of natural and social environments. The rock cavern storage of spent fuel has several advantages compared with the surface storage, and there is no significant difference on the viewpoint of economy between the two alternatives. In addition, no great technical difficulties are present to apply the rock cavern storage technologies to the storage of domestic spent fuel.

  10. Heating effects in Rio Blanco rock

    International Nuclear Information System (INIS)

    Taylor, R.W.; Bowen, D.W.; Rossler, P.E.

    1975-01-01

    Samples of ''sandstone'' from near the site of the upper Rio Blanco nuclear explosion were heated in the laboratory at temperatures between 600 and 900 0 C. The composition and amount of noncondensable (dry) gas released were measured and compared to the amount and composition of gas found underground following the explosion. The gas released from the rock heated in the laboratory contained approximately 80 percent CO 2 and 10 percent H 2 ; the balance was CO and CH 4 . With increasing temperature, the amounts of CO 2 , CO, and H 2 released increased. The composition of gas released by heating Rio Blanco rock in the laboratory is similar to the composition of gas found after the nuclear explosion except that it contains less natural gas (CH 4 , C 2 H 6 . . .). The amount of noncondensable gas released by heating the rock increases from approximately 0.1 mole/kg of rock at 600 0 C to 0.9 mole/kg at 900 0 C. Over 90 percent of the volatile components of the rock are released in less than 10 h at 900 0 C. A comparison of the amount of gas released by heating rock in the laboratory to the amount of gas released by the heat of the Rio Blanco nuclear explosion suggests that the explosion released the volatile material from about 0.42 mg of rock per joule of explosive energy (1700 to 1800 tonnes per kt). (auth)

  11. Discussion on the origin of sedimentary rock resistivity

    International Nuclear Information System (INIS)

    Dong Gangjian

    2012-01-01

    Conduction current way of sedimentary rock sedimentary rock is caused by the internal structure of sedimentary rock sedimentary rock pore resistance depends on the salinity of pore water and clay content and distribution. Resistivity of sedimentary rock sedimentary rock major factor in mineral composition, water resistance, oil resistance. and sedimentary structures. In practice, we should give full attention to the difference between lithology and physical properties. (author)

  12. The Usability of Rock-Like Materials for Numerical Studies on Rocks

    Science.gov (United States)

    Zengin, Enes; Abiddin Erguler, Zeynal

    2017-04-01

    The approaches of synthetic rock material and mass are widely used by many researchers for understanding the failure behavior of different rocks. In order to model the failure behavior of rock material, researchers take advantageous of different techniques and software. But, the majority of all these instruments are based on distinct element method (DEM). For modeling the failure behavior of rocks, and so to create a fundamental synthetic rock material model, it is required to perform related laboratory experiments for providing strength parameters. In modelling studies, model calibration processes are performed by using parameters of intact rocks such as porosity, grain size, modulus of elasticity and Poisson ratio. In some cases, it can be difficult or even impossible to acquire representative rock samples for laboratory experiments from heavily jointed rock masses and vuggy rocks. Considering this limitation, in this study, it was aimed to investigate the applicability of rock-like material (e.g. concrete) to understand and model the failure behavior of rock materials having complex inherent structures. For this purpose, concrete samples having a mixture of %65 cement dust and %35 water were utilized. Accordingly, intact concrete samples representing rocks were prepared in laboratory conditions and their physical properties such as porosity, pore size and density etc. were determined. In addition, to acquire the mechanical parameters of concrete samples, uniaxial compressive strength (UCS) tests were also performed by simultaneously measuring strain during testing. The measured physical and mechanical properties of these extracted concrete samples were used to create synthetic material and then uniaxial compressive tests were modeled and performed by using two dimensional discontinuum program known as Particle Flow Code (PFC2D). After modeling studies in PFC2D, approximately similar failure mechanism and testing results were achieved from both experimental and

  13. Look! It's Rock'n'roll!

    DEFF Research Database (Denmark)

    Lindelof, Anja

    2007-01-01

    , and dates. Consult your library or click here for more information on citing sources. -------------------------------------------------------------------------------- Anja Mølle Lindelof. (2007). Look! it's rock'n'roll! how television participated in shaping the visual genre conventions of popular music...... to personal names, capitalization, and dates. Consult your library or click here for more information on citing sources. -------------------------------------------------------------------------------- Anja Mølle Lindelof. "Look! It's Rock'n'roll! How television participated in shaping the visual genre....... Pay special attention to personal names, capitalization, and dates. Consult your library or click here for more information on citing sources. -------------------------------------------------------------------------------- TY - JOUR T1 - Look! It's Rock'n'roll! How television participated in shaping...

  14. Permeability Evolution and Rock Brittle Failure

    OpenAIRE

    Sun Qiang; Xue Lei; Zhu Shuyun

    2015-01-01

    This paper reports an experimental study of the evolution of permeability during rock brittle failure and a theoretical analysis of rock critical stress level. It is assumed that the rock is a strain-softening medium whose strength can be described by Weibull’s distribution. Based on the two-dimensional renormalization group theory, it is found that the stress level λ c (the ratio of the stress at the critical point to the peak stress) depends mainly on the homogeneity index or shape paramete...

  15. Deep fracturation of granitic rock mass

    International Nuclear Information System (INIS)

    Bles, J.L.; Blanchin, R.; Bonijoly, D.; Dutartre, P.; Feybesse, J.L.; Gros, Y.; Landry, J.; Martin, P.

    1986-01-01

    This documentary study realized with the financial support of the European Communities and the CEA aims at the utilization of available data for the understanding of the evolution of natural fractures in granitic rocks from the surface to deep underground, in various feasibility studies dealing with radioactive wastes disposal. The Mont Blanc road tunnel, the EDF Arc-Isere gallerie, the Auriat deep borehole and the Pyrenean rock mass of Bassies are studied. In this study are more particularly analyzed the relationship between small fractures and large faults, evolution with depth of fracture density and direction, consequences of rock decompression and relationship between fracturation and groundwater [fr

  16. Radon and rock bursts in deep mines

    International Nuclear Information System (INIS)

    Bulashevich, Yu.P.; Utkin, V.I.; Yurkov, A.K.; Nikolaev, V.V.

    1996-01-01

    Variation fields of radon concentration in time to ascertain stress-strain state of the North Ural bauxite mines have been studied. It is shown that dynamic changes in the stress-strain state of the rocks prior to the rock burst bring about variations in radon concentration in the observation wells. Depending on mutual positioning of the observation points and the rock burst epicenter, the above-mentioned variations differ in principle, reduction of radon concentration in the near zone and its increase in the far zone are observed [ru

  17. Laboratory measurements of rock thermal properties

    DEFF Research Database (Denmark)

    Bording, Thue Sylvester; Balling, N.; Nielsen, S.B.

    The thermal properties of rocks are key elements in understanding and modelling the temperature field of the subsurface. Thermal conductivity and thermal diffusivity can be measured in the laboratory if rock samples can be provided. We have introduced improvements to the divided bar and needle...... probe methods to be able to measure both thermal conductivity and thermal diffusivity. The improvements we implement include, for both methods, a combination of fast numerical finite element forward modelling and a Markov Chain Monte Carlo inversion scheme for estimating rock thermal parameters...

  18. Acoustics in rock and pop music halls

    DEFF Research Database (Denmark)

    Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of rhythmic music, including rock and pop. Objective measurements were made of the acoustics of twenty rock music venues...... in Denmark and a questionnaire was used in a subjective assessment of those venues with professional rock musicians and sound engineers. Correlations between the objective and subjective results lead, among others, to a recommendation for reverberation time as a function of hall volume. Since the bass...

  19. Lead isotopes in archaean plutonic rocks

    International Nuclear Information System (INIS)

    Oversby, V.M.

    1978-01-01

    Archaean intrusive rocks have initial Pb isotopic compositions which show a varied and complex history for the source regions of the rocks. Even the oldest rocks from Greenland indicate heterogenous U and Pb distribution prior to 3800 m.y. ago. Source regions with μ values less than 7 must have played a significant role in the early history of the earth. By late Archaean time U/Pb ratios of source regions had increased substantially. Data from Australia and North America show distinct regional differences, both within and between continents. (Auth.)

  20. Heat production / host rock compatibility; Waermeentwicklung / Gesteinsvertraeglichkeit

    Energy Technology Data Exchange (ETDEWEB)

    Meleshyn, A.; Weyand, T.; Bracke, G.; Kull, H.; Wieczorek, K.

    2016-05-15

    For the final high-level radioactive waste repository potential host rock formations are either rock salt or clays (Kristallin). Heat generating waste (decay heat of the radioactive materials) can be absorbed by the host rock. The effect of temperature increase on the thermal conductivity, the thermal expansion and the mechanical properties of salt, Kristallin, clays and argilliferous geotechnical barriers are described. Further issues of the report are the mineralogical behavior, phase transformations, hydrochemistry, microbial processes, gas formation, thermochemical processes and gas ingress. Recommendations for further research are summarized.

  1. Rapid formation of rock armour for soil - rock fragment mixture during simulated rainfall

    Science.gov (United States)

    Poultney, E.; McGrath, G. S.; Hinz, C.

    2009-04-01

    Preventing erosion is an important issue in disturbed semi-arid and arid landscapes. This is in particular of highest importance for mining companies while undertaking land rehabilitation. An onsite investigation of the impact of surface rock fragments on erosion was conducted at Telfer goldmine in the Great Sandy Desert, Western Australia. The study site is a waste rock dump designed to mimic the concave slope of a natural mesa to both discourage erosion and blend in with its natural surroundings. Four treatments were used to construct the slope: two are topsoil mixed with rock fragments, and two are unmixed topsoil. A field study investigating erosion rills, particle size distribution, rock fragment coverage surface roughness and vegetation was carried out to determine changes down and across slope. The treatments constructed by mixing topsoil and rock fragments are more stable and show rock fragment distributions that more closely resemble patterns found on natural mesas surrounding Telfer. A controlled study using trays of topsoil mixed with rock fragment volumes of 50%, 60%, 70% and 80% were used to investigate how varying mixtures of rock fragments and topsoil erode using rainfall intensities between 20 and 100 mm h-1. Two runs of 25 minutes each were used to assess the temporal evolution of rock armouring. Surface coverage results converged for the 50%, 60% and 70% mixtures after the first run to coverage of about 90%, suggesting that fine sediment proportion does not affect rate and degree of rock armouring.

  2. Sliding rocks on Racetrack Playa, Death Valley National Park: first observation of rocks in motion.

    Directory of Open Access Journals (Sweden)

    Richard D Norris

    Full Text Available The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved > 60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, "windowpane" ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of -4-5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2-5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice.

  3. Effects of confinement on rock mass modulus: A synthetic rock mass modelling (SRM study

    Directory of Open Access Journals (Sweden)

    I. Vazaios

    2018-06-01

    Full Text Available The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks (well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints. A synthetic rock mass modelling (SRM approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method (DEM-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the pre-existing joints is generated by employing discrete fracture network (DFN modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation (RQD, joint spacing, areal fracture intensity (P21, and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index (GSI. The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness. Keywords: Synthetic rock mass modelling (SRM, Discrete fracture network (DFN, Rock mass modulus, Geological strength index (GSI, Confinement

  4. Photosynthesis in the Archean era.

    Science.gov (United States)

    Olson, John M

    2006-05-01

    The earliest reductant for photosynthesis may have been H2. The carbon isotope composition measured in graphite from the 3.8-Ga Isua Supercrustal Belt in Greenland is attributed to H2-driven photosynthesis, rather than to oxygenic photosynthesis as there would have been no evolutionary pressure for oxygenic photosynthesis in the presence of H2. Anoxygenic photosynthesis may also be responsible for the filamentous mats found in the 3.4-Ga Buck Reef Chert in South Africa. Another early reductant was probably H2S. Eventually the supply of H2 in the atmosphere was likely to have been attenuated by the production of CH4 by methanogens, and the supply of H2S was likely to have been restricted to special environments near volcanos. Evaporites, possible stromatolites, and possible microfossils found in the 3.5-Ga Warrawoona Megasequence in Australia are attributed to sulfur-driven photosynthesis. Proteobacteria and protocyanobacteria are assumed to have evolved to use ferrous iron as reductant sometime around 3.0 Ga or earlier. This type of photosynthesis could have produced banded iron formations similar to those produced by oxygenic photosynthesis. Microfossils, stromatolites, and chemical biomarkers in Australia and South Africa show that cyanobacteria containing chlorophyll a and carrying out oxygenic photosynthesis appeared by 2.8 Ga, but the oxygen level in the atmosphere did not begin to increase until about 2.3 Ga.

  5. Biogenic Cracks in Porous Rock

    Science.gov (United States)

    Hemmerle, A.; Hartung, J.; Hallatschek, O.; Goehring, L.; Herminghaus, S.

    2014-12-01

    Microorganisms growing on and inside porous rock may fracture it by various processes. Some of the mechanisms of biofouling and bioweathering are today identified and partially understood but most emphasis is on chemical weathering, while mechanical contributions have been neglected. However, as demonstrated by the perseverance of a seed germinating and cracking up a concrete block, the turgor pressure of living organisms can be very significant. Here, we present results of a systematic study of the effects of the mechanical forces of growing microbial populations on the weathering of porous media. We designed a model porous medium made of glass beads held together by polydimethylsiloxane (PDMS), a curable polymer. The rheological properties of the porous medium, whose shape and size are tunable, can be controlled by the ratio of crosslinker to base used in the PDMS (see Fig. 1). Glass and PDMS being inert to most chemicals, we are able to focus on the mechanical processes of biodeterioration, excluding any chemical weathering. Inspired by recent measurements of the high pressure (~0.5 Mpa) exerted by a growing population of yeasts trapped in a microfluidic device, we show that yeast cells can be cultured homogeneously within porous medium until saturation of the porous space. We investigate then the effects of such an inner pressure on the mechanical properties of the sample. Using the same model system, we study also the complex interplay between biofilms and porous media. We focus in particular on the effects of pore size on the penetration of the biofilm within the porous sample, and on the resulting deformations of the matrix, opening new perspectives into the understanding of life in complex geometry. Figure 1. Left : cell culture growing in a model porous medium. The white spheres represent the grains, bonds are displayed in grey, and microbes in green. Right: microscopy picture of glass beads linked by PDMS bridges, scale bar: 100 μm.

  6. Wing rock suppression using forebody vortex control

    Science.gov (United States)

    Ng, T. T.; Ong, L. Y.; Suarez, C. J.; Malcolm, G. N.

    1991-01-01

    Static and free-to-roll tests were conducted in a water tunnel with a configuration that consisted of a highly-slender forebody and 78-deg sweep delta wings. Flow visualization was performed and the roll angle histories were obtained. The fluid mechanisms governing the wing rock of this configuration were identified. Different means of suppressing wing rock by controlling the forebody vortices using small blowing jets were also explored. Steady blowing was found to be capable of suppressing wing rock, but significant vortex asymmetries had to be induced at the same time. On the other hand, alternating pulsed blowing on the left and right sides of the forebody was demonstrated to be potentially an effective means of suppressing wing rock and eliminating large asymmetric moments at high angles of attack.

  7. RELIABILITY OF TRANSPORTATION SYSTEMS OF ROCK HAPS

    Directory of Open Access Journals (Sweden)

    A. Stepanov

    2009-01-01

    Full Text Available The ways of increasing of exploitation reliability of dump trucks with the aim of increasing of effectiveness of exploitation of transportation systems of rock heaps at coal mines.

  8. Rock bed heat accumulators. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Riaz, M.

    1977-12-01

    The principal objectives of the research program on rock bed heat accumulators (or RBHA) are: (1) to investigate the technical and economic feasibility of storing large amounts of thermal energy (in the tens of MWt range) at high temperature (up to 500/sup 0/C) over extended periods of time (up to 6 months) using native earth or rock materials; (2) to conduct studies to establish the performance characteristics of large rock bed heat accumulators at various power and temperature levels compatible with thermal conversion systems; and (3) to assess the materials and environmental problems associated with the operation of such large heat accumulators. Results of the study indicate that rock bed heat accumulators for seasonal storage are both technically and economically feasible, and hence could be exploited in various applications in which storage plays an essential role such as solar power and total energy systems, district and cogeneration heating systems.

  9. Cretaceous rocks of the Western Interior basin

    International Nuclear Information System (INIS)

    Molenaar, C.M.; Rice, D.D.

    1988-01-01

    The Cretaceous rocks of the conterminous United States are discussed in this chapter. Depositional facies and lithology are reviewed along with economic resources. The economic resources include coal, hydrocarbons, and uranium

  10. Mechanical dispersion in fractured crystalline rock systems

    International Nuclear Information System (INIS)

    Lafleur, D.W.; Raven, K.G.

    1986-12-01

    This report compiles and evaluates the hydrogeologic parameters describing the flow of groundwater and transport of solutes in fractured crystalline rocks. This report describes the processes of mechanical dispersion in fractured crystalline rocks, and compiles and evaluates the dispersion parameters determined from both laboratory and field tracer experiments. The compiled data show that extrapolation of the reliable test results performed over intermediate scales (10's of m and 10's to 100's of hours) to larger spatial and temporal scales required for performance assessment of a nuclear waste repository in crystalline rock is not justified. The reliable measures of longitudinal dispersivity of fractured crystalline rock are found to range between 0.4 and 7.8 m

  11. Dating oxalate minerals in rock surface deposits

    International Nuclear Information System (INIS)

    Watchman, A.

    2001-01-01

    Oxalate minerals are found associated with rocks, mineral coatings, micro-organisms, plants and animals. They are important in archaeology because they have been found intimately associated with organic binders in prehistoric paints. Oxalate minerals also accumulate in the coatings on rock shelter walls and fallen ceiling slabs where they form the natural backing supports for painting and opaque laminates covering engravings. Though the relationship between anthropogenic activity in a rock shelter and oxalate formation is often uncertain, the radiocarbon age of the oxalate may provide the only means for determining the antiquity of a rock painting or engraving. This paper examines the history of dating oxalate minerals at archaeological sites and provides insights into achieving reliable age estimates. (author). 37 refs., 1 fig., 2 tabs

  12. ROCK GLACIERS IN THE KOLYMA HIGHLAND

    Directory of Open Access Journals (Sweden)

    A. A. Galanin

    2012-01-01

    Full Text Available Based on remote mapping and field studies inGrand Rapids, Tumansky,Hasynsky,Del-Urechen Ridges as well as Dukchinsky and Kilgansky Mountain Massifs there were identified about 1160 landforms which morphologically are similar to the rock glaciers or they develop in close association with them. Besides tongue-shaped cirque rock glaciers originated due to ablation, a large number of lobate-shaped slope-associated rock glaciers were recognized. Significant quantity of such forms are developing within the active neotectonic areas, in zones of seismic-tectonic badland and in association with active earthquakes-controlling faults. Multiplication of regional data on volcanic-ash-chronology, lichenometry, Schmidt Hammer Test, pollen spectra and single radiocarbon data, most of the active rock glaciers were preliminary attributed to the Late Holocene.

  13. Rock glaciers, Prealps, Vaud, Switzerland, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The investigated area forms part of the western lobe of the Prealps (Swiss Prealps). The 25 identified fossil rock glaciers are found mainly in the Prealpes medianes...

  14. Mechanical properties of rock at high temperatures

    International Nuclear Information System (INIS)

    Kinoshita, Naoto; Abe, Tohru; Wakabayashi, Naruki; Ishida, Tsuyoshi.

    1997-01-01

    The laboratory tests have been performed in order to investigate the effects of temperature up to 300degC and pressure up to 30 MPa on the mechanical properties of three types of rocks, Inada granite, Sanjoume andesite and Oya tuff. The experimental results indicated that the significant differences in temperature dependence of mechanical properties exist between the three rocks, because of the difference of the factors which determine the mechanical properties of the rocks. The effect of temperature on the mechanical properties for the rocks is lower than that of pressure and water content. Temperature dependence of the mechanical properties is reduced by increase in pressure in the range of pressure and temperature investigated in this paper. (author)

  15. Pore-scale analysis of electrical properties in thinly bedded rock using digital rock physics

    International Nuclear Information System (INIS)

    Sun, Jianmeng; Zhao, Jianpeng; Liu, Xuefeng; Chen, Hui; Jiang, LiMing; Zhang, JinYan

    2014-01-01

    We investigated the electrical properties of laminated rock consist of macro-porous layers and micro-porous layers based on digital rock technology. Due to the bedding effect and anisotropy, traditional Archie equations cannot well describe the electrical behavior of laminated rock. The RI-Sw curve of laminated rock shows a nonlinear relationship. The RI-Sw curve can be divided into two linear segments with different saturation exponent. Laminated sand-shale sequences and laminated sands of different porosity or grain size will yield macroscopic electrical anisotropy. Numerical simulation and theoretical analysis lead to the conclusion that electrical anisotropy coefficient of laminated rock is a strong function of water saturation. The function curve can be divided into three segments by the turning point. Therefore, the electrical behavior of laminated rock should be considered in oil exploration and development. (paper)

  16. Evaluation of dynamic characteristics of hard rock based on numerical simulations of in situ rock tests

    International Nuclear Information System (INIS)

    Yamagami, Yuya; Ikusada, Koji; Jiang, Yujing

    2009-01-01

    In situ rock tests of hard rock of conglomerate in which discontinuities in high angle are dominant were conducted. In this study, in order to confirm the validity of the test results and the test condition, and in order to elucidate the deformation behaviour and the mechanism of shear strength of the rock mass, the numerical simulations of the in situ rock tests by using distinct element method were performed. As a result, it was clarified that the behaviour of the rock mass strongly depends on both geometrical distribution of discontinuities and those mechanical properties. It is thought that a series of evaluation processes showed in this study contribute to improve the reliability of the dynamic characteristic evaluation of the rock mass. (author)

  17. ONKALO rock mechanics model (RMM). Version 2.3

    Energy Technology Data Exchange (ETDEWEB)

    Haekkinen, T.; Merjama, S.; Moenkkoenen, H. [WSP Finland, Helsinki (Finland)

    2014-07-15

    The Rock Mechanics Model of the ONKALO rock volume includes the most important rock mechanics features and parameters at the Olkiluoto site. The main objective of the model is to be a tool to predict rock properties, rock quality and hence provide an estimate for the rock stability of the potential repository at Olkiluoto. The model includes a database of rock mechanics raw data and a block model in which the rock mechanics parameters are estimated through block volumes based on spatial rock mechanics raw data. In this version 2.3, special emphasis was placed on refining the estimation of the block model. The model was divided into rock mechanics domains which were used as constraints during the block model estimation. During the modelling process, a display profile and toolbar were developed for the GEOVIA Surpac software to improve visualisation and access to the rock mechanics data for the Olkiluoto area. (orig.)

  18. Relating rock avalanche morphology to emplacement processes

    Science.gov (United States)

    Dufresne, Anja; Prager, Christoph; Bösmeier, Annette

    2015-04-01

    The morphology, structure and sedimentological characteristics of rock avalanche deposits reflect both internal emplacement processes and external influences, such as runout path characteristics. The latter is mainly predisposed by topography, substrate types, and hydrogeological conditions. Additionally, the geological setting at the source slope controls, e.g. the spatial distribution of accumulated lithologies and hence material property-related changes in morphology, or the maximum clast size and amount of fines of different lithological units. The Holocene Tschirgant rock avalanche (Tyrol, Austria) resulted from failure of an intensely deformed carbonate rock mass on the southeast face of a 2,370-m-high mountain ridge. The initially sliding rock mass rapidly fragmented as it moved towards the floor of the Inn River valley. Part of the 200-250 x 106 m3 (Patzelt 2012) rock avalanche debris collided with and moved around an opposing bedrock ridge and flowed into the Ötz valley, reaching up to 6.3 km from source. Where the Tschirgant rock avalanche spread freely it formed longitudinal ridges aligned along motion direction as well as smaller hummocks. Encountering high topography, it left runup ridges, fallback patterns (i.e. secondary collapse), and compressional morphology (successively elevated, transverse ridges). Further evidence for the mechanical landslide behaviour is given by large volumes of mobilized valley-fill sediments (polymict gravels and sands). These sediments indicate both shearing and compressional faulting within the rock avalanche mass (forming their own morphological units through, e.g. in situ bulldozing or as distinctly different hummocky terrain), but also indicate extension of the spreading landslide mass (i.e. intercalated/injected gravels encountered mainly in morphological depressions between hummocks). Further influences on its morphology are given by the different lithological units. E.g. the transition from massive dolomite

  19. Remarks on some rock neutron parameters

    International Nuclear Information System (INIS)

    Czubek, J.A.

    1984-01-01

    A method to calculate the thermal neutron parameters of rocks is given in the paper. It is based on a proper energy averaging of cross-sections for all rock matrix and rock saturating liquid constituents. The diffusion lengths in different lithologies in function of the variable rock porosity have been calculated. An influence of the thermal neutron spectrum on the shape of the porosity calibration curves for the dual spacing neutron method is shown. Magmatic rocks as a possible source of geothermal energy are now becoming a target of neutron loggings for the porosity determination. Here the knowledge of the slowing-down lengths is of great importance in the problem of the estimation of the calibration curves. A semi-analytical approach to get this parameter is given in the paper. It was found, as far as concerns the slowing-down of fast neutrons, that all magmatic rocks behave as sandstone with, however, different content of bound water in the rock matrix and different rock matrix density. Some neutron methods are based on the detection of epithermal neutrons. For theoretical considerations it is important to know the physical meaning of the registered signal. From the discussion of experimental data reported in the literature it seems that it is the slowing-down density that is the physical quantity being measured. This conclusion has a very important practical implication - the porosity calibration curves depend upon the slowing-down length alone and are independent of the slowing-down cross-section for epithermal neutrons

  20. Digital Rock Studies of Tight Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Silin, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-07

    This technical report summarizes some recently developed approaches to studies of rock properties at a pore scale. Digital rock approach is complementary to laboratory and field studies. It can be especially helpful in situations where experimental data are uncertain, or are difficult or impossible to obtain. Digitized binary images of the pore geometries of natural rocks obtained by different imaging techniques are the input data. Computer-generated models of natural rocks can be used instead of images in a case where microtomography data are unavailable, or the resolution of the tools is insufficient to adequately characterize the features of interest. Simulations of creeping viscous flow in pores produce estimates of Darcy permeability. Maximal Inscribed Spheres calculations estimate two-phase fluid distribution in capillary equilibrium. A combination of both produce relative permeability curves. Computer-generated rock models were employed to study two-phase properties of fractured rocks, or tight sands with slit-like pores, too narrow to be characterized with micro-tomography. Various scenarios can simulate different fluid displacement mechanisms, from piston-like drainage to liquid dropout at the dew point. A finite differences discretization of Stokes equation is developed to simulate flow in the pore space of natural rocks. The numerical schemes are capable to handle both no-slip and slippage flows. An upscaling procedure estimates the permeability by subsampling a large data set. Capillary equilibrium and capillary pressure curves are efficiently estimated with the method of maximal inscribed spheres both an arbitrary contact angle. The algorithms can handle gigobytes of data on a desktop workstation. Customized QuickHull algorithms model natural rocks. Capillary pressure curves evaluated from computer-generated images mimic those obtained for microtomography data.

  1. Rock excavation by pulsed electron beams

    International Nuclear Information System (INIS)

    Avery, R.T.; Keefe, D.; Brekke, T.L.; Finnie, I.

    1976-03-01

    If an intense short pulse of megavolt electrons is deposited in a brittle solid, dynamic spalling can be made to occur with removal of material. Experiments were made on several types of hard rock; results are reproducible and well-described theoretically. An accelerator with a rapidly-pulsed scanning electron beam was designed that could tunnel in hard rock about ten times faster than conventional drill/blast methods

  2. Rock excavation by pulsed electron beams

    International Nuclear Information System (INIS)

    Avery, R.T.; Keefe, D.; Brekke, T.L.; Finnie, I.

    1976-01-01

    If an intense short pulse of megavolt electrons is deposited in a brittle solid, dynamic spalling can be made to occur with removal of material. Experiments have been made on several types of hard rock; results are reproducible and well-described theoretically. An accelerator with a rapid-pulsed scanning electron-beam has been designed that could tunnel in hard rock about ten times faster than conventional drill/blast methods. (author)

  3. The Dalradian rocks of Scotland: an introduction

    OpenAIRE

    Stephenson, David; Mendum, John R.; Fettes, Douglas J.; Leslie, A. Graham

    2013-01-01

    The Dalradian Supergroup and its basement rocks, together with younger plutons, underpin most of the Grampian Highlands and the islands of the Inner Hebrides between the Highland Boundary and Great Glen faults. The Dalradian is a mid-Neoproterozoic to early-Ordovician sequence of largely clastic metasedimentary rocks, with some volcanic units, which were deformed and metamorphosed to varying degrees during the Early Palaeozoic Caledonian Orogeny. Sedimentation of the lower parts of the Da...

  4. Developing a Virtual Rock Deformation Laboratory

    Science.gov (United States)

    Zhu, W.; Ougier-simonin, A.; Lisabeth, H. P.; Banker, J. S.

    2012-12-01

    Experimental rock physics plays an important role in advancing earthquake research. Despite its importance in geophysics, reservoir engineering, waste deposits and energy resources, most geology departments in U.S. universities don't have rock deformation facilities. A virtual deformation laboratory can serve as an efficient tool to help geology students naturally and internationally learn about rock deformation. Working with computer science engineers, we built a virtual deformation laboratory that aims at fostering user interaction to facilitate classroom and outreach teaching and learning. The virtual lab is built to center around a triaxial deformation apparatus in which laboratory measurements of mechanical and transport properties such as stress, axial and radial strains, acoustic emission activities, wave velocities, and permeability are demonstrated. A student user can create her avatar to enter the virtual lab. In the virtual lab, the avatar can browse and choose among various rock samples, determine the testing conditions (pressure, temperature, strain rate, loading paths), then operate the virtual deformation machine to observe how deformation changes physical properties of rocks. Actual experimental results on the mechanical, frictional, sonic, acoustic and transport properties of different rocks at different conditions are compiled. The data acquisition system in the virtual lab is linked to the complied experimental data. Structural and microstructural images of deformed rocks are up-loaded and linked to different deformation tests. The integration of the microstructural image and the deformation data allows the student to visualize how forces reshape the structure of the rock and change the physical properties. The virtual lab is built using the Game Engine. The geological background, outstanding questions related to the geological environment, and physical and mechanical concepts associated with the problem will be illustrated on the web portal. In

  5. Rock Moved by Mars Lander Arm

    Science.gov (United States)

    2008-01-01

    The robotic arm on NASA's Phoenix Mars Lander slid a rock out of the way during the mission's 117th Martian day (Sept. 22, 2008) to gain access to soil that had been underneath the rock.The lander's Surface Stereo Imager took the two images for this stereo view later the same day, showing the rock, called 'Headless,' after the arm pushed it about 40 centimeters (16 inches) from its previous location. 'The rock ended up exactly where we intended it to,' said Matt Robinson of NASA's Jet Propulsion Laboratory, robotic arm flight software lead for the Phoenix team. The arm had enlarged the trench near Headless two days earlier in preparation for sliding the rock into the trench. The trench was dug to about 3 centimeters (1.2 inches) deep. The ground surface between the rock's prior position and the lip of the trench had a slope of about 3 degrees downward toward the trench. Headless is about the size and shape of a VHS videotape. The Phoenix science team sought to move the rock in order to study the soil and the depth to subsurface ice underneath where the rock had been. This image was taken at about 12:30 p.m., local solar time on Mars. The view is to the north northeast of the lander. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by JPL, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

  6. Preliminary rock mechanics laboratory: Investigation plan

    International Nuclear Information System (INIS)

    Oschman, K.P.; Hummeldorf, R.G.; Hume, H.R.; Karakouzian, M.; Vakili, J.E.

    1987-01-01

    This document presents the rationale for rock mechanics laboratory testing (including the supporting analysis and numerical modeling) planned for the site characterization of a nuclear waste repository in salt. This plan first identifies what information is required for regulatory and design purposes, and then presents the rationale for the testing that satisfies the required information needs. A preliminary estimate of the minimum sampling requirements for rock laboratory testing during site characterization is also presented. Periodic revision of this document is planned

  7. Nuclear power in rock. Principal report

    International Nuclear Information System (INIS)

    1977-06-01

    In September 1975 the Swedish Government directed the Swedish State Power Board to study the question of rock-siting nuclear power plants. The study accounted for in this report aims at clarifying the advantages and disadvantages of siting a nuclear power plant in rock, compared to siting on ground level, considering reactor safety, war protection and sabotage. The need for nuclear power production during war situations and the closing down of nuclear power plants after terminated operation are also dealt with. (author)

  8. Underground large scale test facility for rocks

    International Nuclear Information System (INIS)

    Sundaram, P.N.

    1981-01-01

    This brief note discusses two advantages of locating the facility for testing rock specimens of large dimensions in an underground space. Such an environment can be made to contribute part of the enormous axial load and stiffness requirements needed to get complete stress-strain behavior. The high pressure vessel may also be located below the floor level since the lateral confinement afforded by the rock mass may help to reduce the thickness of the vessel

  9. Method of degassifying a massive of rock

    Energy Technology Data Exchange (ETDEWEB)

    Levin, M M; Krivosheev, V O; Preobrazhenskaia, E I; Talapkerov, A Sh; Taushkin, G T

    1979-05-30

    This invention concerns the mining industry, chiefly the coal industry, and can be used for the degasification of coal layers and interfering rock. The method of preliminary extraction of gas with underground development of burning minerals, including the pumping of gas through a collector, carried in the plane of the degasifying layer, discharged from rock pressure by means of extracting the lower lying layer, is known. However, the given method does not make it possible to degasify the interfering rock. Another method, consisting of the fact that from the mining development in the lateral rock, chambers are made, from which a group of wells are bored, and the latter are united with the gas removing system, is well known. This method has the inadequacy that the well of each chamber is connected to the gas removing system of the pipelines, and this leads to an increase in the price of the method. A new system is presented for the degasification of the massive of rock which is presented in an illustration...... The advantage of the suggested method consists of the fact that material outlays are reduced for the unification of each chamber with the gas removing pipeline, and besides this, the wells, connecting the chambers are drains for the surrounding rock, which increases the effectiveness of the degasification.

  10. The Rock that Hit New York

    Energy Technology Data Exchange (ETDEWEB)

    Meade, Roger Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Keksis, August Lawrence [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-10-03

    On January 12, 1975, a rock seemed to fall from the sky over New York State’s Schoharie County hitting the tractor of a local farmer, who was “preparing his fields for spring planting.” As the farmer later described the event to a reporter from the UFO INVESTIGATOR, the object glanced off the tractor, fell to the ground, and melted its way through a patch of ice that was two and one half inches thick. The farmer, Leonard Tillapaugh, called the county sheriff, Harvey Stoddard, who recovered the rock, noting that it “was still warm.” Why and how a sample of the rock came to Los Alamos is not known. However, it captivated a wide Laboratory audience, was subjected to rigorous testing and evaluation. Los Alamos used the scientific method in the manner promoted by Hynek. Did Los Alamos solve the mystery of the rock’s origin? Not definitively. Although the exact origin could not be determined, it was shown conclusively that the rock was not from outer space. With that said, the saga of Rock that hit New York came to an end. Nothing more was said or written about it. The principals involved have long since passed from the scene. The NICAP ceased operations in 1980. And, the rock, itself, has disappeared.

  11. Investigation of the porosity of rocks

    International Nuclear Information System (INIS)

    Hellmuth, K.H.; Siitari-Kauppi, M.

    1990-06-01

    Methods for characterizing the nature of rock porosity in conjunction with diffusion experiments, are amongst the primary tools used in repository-site selection investigations. At this time no experimental method, alone, is capable of giving an unambiguous picture of the narrow-aperture pore space in crystalline rock. Methods giving information on overall properties must be complemented by those having high spatial resolution; then the lateral distribution of porosity within the matrix and its association with particular mineral phases or features, such as microfissures, fissure fillings, weathered or altered mineral phases etc, and the identification of diffusion pathways in inhomogeneous rock matrices can be determined. Nonsorbing, nonelectrolytic tracers should be used when one wants to determine rock-typical properties of the internal porosity without interference of interactions with surfaces. Preliminary information on a new method fulfilling these criteria is given. Impregnating rock samples with methylmethacrylate labeled with carbon-14 which, after impregnation, was polymerized by gamma radiation, gave specimens that made preparation of sections suitable for quantification by autoradiographic methods easy. Diffusion experiments can be conducted so that labeled MMA diffuses out of rock specimens into inactive free, MMA. Additional information may be gained by leaching PMMA fractions of lower molecular weight from the matrix

  12. Rock burst prevention at steep seam mining

    Energy Technology Data Exchange (ETDEWEB)

    Efremov, G D

    1988-09-01

    At steep shield longwalls one method of preventing rock bursts is to avoid sharp angles during working. Stress in coal and rock body that appears when steep seams are worked where rock bursts occur at corners of set-up entries is discussed. The dynamic interaction between gas and rock pressure is assessed. Maintains that in order to avoid rock bursts at these places it is necessary to turn the protruding coal wall by 20-30 degrees towards the coal body to divert the action of shift forces. At the same time the face should also be inclined (by 10-15 degrees) to move the zones of increased stress away from the corner into the coal and rock body. Stress at workings with round cross-sections is 3-4 times lower than at square cross-sections. Recommendations are given that concern shearer loader operation (semi-spherical shape of the face), borehole drilling and water injection. Initial distance of 10-15 m between boreholes is suggested. 3 refs.

  13. Radionuclide migration in crystalline rock fractures

    International Nuclear Information System (INIS)

    Hoelttae, P.

    2002-01-01

    Crystalline rock has been considered as a host medium for the repository of high radioactive spent nuclear fuel in Finland. The geosphere will act as an ultimate barrier retarding the migration of radionuclides to the biosphere if they are released through the technical barriers. Radionuclide transport is assumed to take place along watercarrying fractures, and retardation will occur both in the fracture and within the rock matrix. To be able to predict the transport and retardation of radionuclides in rock fractures and rock matrices, it is essential to understand the different phenomena involved. Matrix diffusion has been indicated to be an important mechanism, which will retard the transport of radionuclides in rock fractures. Both dispersion and matrix diffusion are processes, which can have similar influences on solute breakthrough curves in fractured crystalline rock. In this work, the migration of radionuclides in crystalline rock fractures was studied by means of laboratory scale column methods. The purpose of the research was to gain a better understanding of various phenomena - particularly matrix diffusion - affecting the transport and retardation behaviour of radionuclides in fracture flow. Interaction between radionuclides and the rock matrix was measured in order to test the compatibility of experimental retardation parameters and transport models used in assessing the safety of underground repositories for spent nuclear fuel. Rock samples of mica gneiss and of unaltered, moderately altered and strongly altered tonalite represented different rock features and porosities offering the possibility to determine experimental boundary limit values for parameters describing both the transport and retardation of radionuclides and rock matrix properties. The dominant matrix diffusion behaviour was demonstrated in porous ceramic column and gas diffusion experiments. Demonstration of the effects of matrix diffusion in crystalline rock fracture succeeded for the

  14. Marked dietary differences between sympatric feral rock doves and ...

    African Journals Online (AJOL)

    1993-06-24

    Jun 24, 1993 ... Although feral rock doves Columba Iivia and rock pigeons C. guinea fly daily in mixed flocks between roosting and nesting sites in Cape Town, South Africa, they feed separately in farmlands north of the city during the austral summer. Examination of the crop contents of 32 feral rock doves and 48 rock ...

  15. Marked dietary differences between sympatric feral rock doves and ...

    African Journals Online (AJOL)

    Although feral rock doves Columba livia and rock pigeons C. guineafly daily in mixed flocks between roosting and nesting sites in Cape Town, South Africa, they feed separately in farmlands north of the city during the austral summer. Examination of the crop contents of 32 feral rock doves and 48 rock pigeons revealed that ...

  16. Rock Physical Interpretation of the Relationship between Dynamic and Static Young's Moduli of Sedimentary Rocks

    Science.gov (United States)

    Takahashi, T.

    2017-12-01

    The static Young's modulus (deformability) of a rock is indispensable for designing and constructing tunnels, dams and underground caverns in civil engineering. Static Young's modulus which is an elastic modulus at large strain level is usually obtained with the laboratory tests of rock cores sampled in boreholes drilled in a rock mass. A deformability model of the entire rock mass is then built by extrapolating the measurements based on a rock mass classification obtained in geological site characterization. However, model-building using data obtained from a limited number of boreholes in the rock mass, especially a complex rock mass, may cause problems in the accuracy and reliability of the model. On the other hand, dynamic Young's modulus which is the modulus at small strain level can be obtained from seismic velocity. If dynamic Young's modulus can be rationally converted to static one, a seismic velocity model by the seismic method can be effectively used to build a deformability model of the rock mass. In this study, we have, therefore, developed a rock physics model (Mavko et al., 2009) to estimate static Young's modulus from dynamic one for sedimentary rocks. The rock physics model has been generally applied to seismic properties at small strain level. In the proposed model, however, the sandy shale model, one of rock physics models, is extended for modeling the static Young's modulus at large strain level by incorporating the mixture of frictional and frictionless grain contacts into the Hertz-Mindlin model. The proposed model is verified through its application to the dynamic Young's moduli derived from well log velocities and static Young's moduli measured in the tri-axial compression tests of rock cores sampled in the same borehole as the logs were acquired. This application proves that the proposed rock physics model can be possibly used to estimate static Young's modulus (deformability) which is required in many types of civil engineering applications

  17. Late Jurassic-Early Cretaceous episodic development of the Bangong Meso-Tethyan subduction: Evidence from elemental and Sr-Nd isotopic geochemistry of arc magmatic rocks, Gaize region, central Tibet, China

    Science.gov (United States)

    Zhang, Yu-Xiu; Li, Zhi-Wu; Yang, Wen-Guang; Zhu, Li-Dong; Jin, Xin; Zhou, Xiao-Yao; Tao, Gang; Zhang, Kai-Jun

    2017-03-01

    The Bangong Meso-Tethys plays a critical role in the development of the Tethyan realm and the initial elevation of the Tibetan Plateau. However, its precise subduction polarity, and history still remain unclear. In this study, we synthesize a report for the Late Jurassic-Early Cretaceous two-phase magmatic rocks in the Gaize region at the southern margin of the Qiangtang block located in central Tibet. These rocks formed during the Late Jurassic-earliest Cretaceous (161-142 Ma) and Early Cretaceous (128-106 Ma), peaking at 146 Ma and 118 Ma, respectively. The presence of inherited zircons indicates that an Archean component exists in sediments in the shallow Qiangtang crust, and has a complex tectonomagmatic history. Geochemical and Sr-Nd isotopic data show that the two-phase magmatic rocks exhibit characteristics of arc magmatism, which are rich in large-ion incompatible elements (LIIEs), but are strongly depleted in high field strength elements (HFSEs). The Late Jurassic-earliest Cretaceous magmatic rocks mixed and mingled among mantle-derived mafic magmas, subduction-related sediments, or crustally-derived felsic melts and fluids, formed by a northward and steep subduction of the Bangong Meso-Tethys ocean crust. The magmatic gap at 142-128 Ma marks a flat subduction of the Meso-Tethys. The Early Cretaceous magmatism experienced a magma MASH (melting, assimilation, storage, and homogenization) process among mantle-derived mafic magmas, or crustally-derived felsic melts and fluids, as a result of the Meso-Tethys oceanic slab roll-back, which triggered simultaneous back-arc rifting along the southern Qiangtang block margin.

  18. Dynamic elastic moduli of rocks under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Schock, R N [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

    1970-05-01

    Elastic moduli are determined as a function of confining pressure to 10 kb on rocks in which Plowshare shots are to be fired. Numerical simulation codes require accurate information on the mechanical response of the rock medium to various stress levels in order to predict cavity dimensions. The theoretical treatment of small strains in an elastic medium relates the propagation velocity of compressional and shear waves to the elastic moduli. Velocity measurements can provide, as unique code input data, the rigidity modulus, Poisson' ratio and the shear wave velocity, as well as providing checks on independent determinations of the other moduli. Velocities are determined using pulsed electro-mechanical transducers and measuring the time-of-flight in the rock specimen. A resonant frequency of 1 MHz is used to insure that the wavelength exceeds the average grain dimension and is subject to bulk rock properties. Data obtained on a variety of rock types are presented and analyzed. These data are discussed in terms of their relationship to moduli measured by static methods as well as the effect of anisotropy, porosity, and fractures. In general, fractured rocks with incipient cracks show large increases in velocity and moduli in the first 1 to 2 kb of compression as a result of the closing of these voids. After this, the velocities increase much more slowly. Dynamic moduli for these rocks are often 10% higher than corresponding static moduli at low pressure, but this difference decreases as the voids are closed until the moduli agree within experimental error. The discrepancy at low pressure is a result of the elastic energy in the wave pulse being propagated around cracks, with little effect on propagation velocity averaged over the entire specimen. (author)

  19. Compact rock material gas permeability properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huanling, E-mail: whl_hm@163.com [Key Laboratory of Coastal Disaster and Defence, Ministry of Education, Hohai University, Nanjing 210098 (China); LML, University of Lille, Cite Scientifique, 59655 Villeneuve d’Ascq (France); Xu, Weiya; Zuo, Jing [Institutes of Geotechnical Engineering, Hohai University, Nanjing 210098 (China)

    2014-09-15

    Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO{sub 2,} shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10{sup −19} m{sup 2}; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10{sup −17} m{sup 2}; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens’ permeability evolution is related to the relative particle movements and microcrack closure.

  20. Measurement of diffusive properties of intact rock

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, K B

    1996-12-01

    In the Postclosure Assessment of a Reference System for the Disposal of Canada`s Nuclear Fuel Waste (Goodwin et al. 1994) the disposal vault is assumed to be surrounded by a zone of intact rock, referred to as the `exclusion zone.` A sensitivity analysis of the relative effectiveness of the several engineered and natural barriers that contribute to the safety of the reference disposal system has shown that this zone of intact rock is the most effective of these barriers to the movement of radionuclides through the reference system. Peer review of the geosphere model used in the case study for the EIS (Environmental Impact Statement) of the Canadian Nuclear Fuel Waste Management Program has identified the need to quantify the properties of the intact rock surrounding the disposal vault that would control the transport of radionuclides by diffusion. The Postclosure Assessment also identified the need for appropriate values of the free water diffusion coefficient (D{sub o}) for {sup 129}1 and {sup 14}C. The measurement of rock resistivity allows the calculation of the Formation Factor for a rock This review describes the Formation Factor, diffusivity, permeability, and porosity, and how these properties might be measured or inferred for insitu rock under the conditions that apply to the intact rock surrounding a potential disposal vault. The importance of measuring the intrinsic diffusion coefficient (D{sup i}) of diffusing species under solution salinities simulating those of groundwaters is emphasised, and a method of measurement is described that is independent of the diffusing medium, and which would be appropriate for measurements made in chemically complex media such as groundwaters. (author). 95 refs., 4 tabs., 39 figs.

  1. Dynamic elastic moduli of rocks under pressure

    International Nuclear Information System (INIS)

    Schock, R.N.

    1970-01-01

    Elastic moduli are determined as a function of confining pressure to 10 kb on rocks in which Plowshare shots are to be fired. Numerical simulation codes require accurate information on the mechanical response of the rock medium to various stress levels in order to predict cavity dimensions. The theoretical treatment of small strains in an elastic medium relates the propagation velocity of compressional and shear waves to the elastic moduli. Velocity measurements can provide, as unique code input data, the rigidity modulus, Poisson' ratio and the shear wave velocity, as well as providing checks on independent determinations of the other moduli. Velocities are determined using pulsed electro-mechanical transducers and measuring the time-of-flight in the rock specimen. A resonant frequency of 1 MHz is used to insure that the wavelength exceeds the average grain dimension and is subject to bulk rock properties. Data obtained on a variety of rock types are presented and analyzed. These data are discussed in terms of their relationship to moduli measured by static methods as well as the effect of anisotropy, porosity, and fractures. In general, fractured rocks with incipient cracks show large increases in velocity and moduli in the first 1 to 2 kb of compression as a result of the closing of these voids. After this, the velocities increase much more slowly. Dynamic moduli for these rocks are often 10% higher than corresponding static moduli at low pressure, but this difference decreases as the voids are closed until the moduli agree within experimental error. The discrepancy at low pressure is a result of the elastic energy in the wave pulse being propagated around cracks, with little effect on propagation velocity averaged over the entire specimen. (author)

  2. Measurement of diffusive properties of intact rock

    International Nuclear Information System (INIS)

    Harvey, K.B.

    1996-12-01

    In the Postclosure Assessment of a Reference System for the Disposal of Canada's Nuclear Fuel Waste (Goodwin et al. 1994) the disposal vault is assumed to be surrounded by a zone of intact rock, referred to as the 'exclusion zone.' A sensitivity analysis of the relative effectiveness of the several engineered and natural barriers that contribute to the safety of the reference disposal system has shown that this zone of intact rock is the most effective of these barriers to the movement of radionuclides through the reference system. Peer review of the geosphere model used in the case study for the EIS (Environmental Impact Statement) of the Canadian Nuclear Fuel Waste Management Program has identified the need to quantify the properties of the intact rock surrounding the disposal vault that would control the transport of radionuclides by diffusion. The Postclosure Assessment also identified the need for appropriate values of the free water diffusion coefficient (D o ) for 129 1 and 14 C. The measurement of rock resistivity allows the calculation of the Formation Factor for a rock This review describes the Formation Factor, diffusivity, permeability, and porosity, and how these properties might be measured or inferred for insitu rock under the conditions that apply to the intact rock surrounding a potential disposal vault. The importance of measuring the intrinsic diffusion coefficient (D i ) of diffusing species under solution salinities simulating those of groundwaters is emphasised, and a method of measurement is described that is independent of the diffusing medium, and which would be appropriate for measurements made in chemically complex media such as groundwaters. (author). 95 refs., 4 tabs., 39 figs

  3. Abraded Target on Rock 'Champagne' in Gusev Crater

    Science.gov (United States)

    2005-01-01

    NASA's Mars Exploration Rover Spirit took this microscopic image of a target called 'Bubbles' on a rock called 'Champagne' after using its rock abrasion tool to grind a hole through the rock's outer surface. The circular area where the rock's interior is exposed is about 5 centimeters (2 inches) across. This rock is different from rocks out on the plains of Gusev Crater but is similar to other rocks in this area of the 'Columbia Hills' in that it rich in phosphorus. Plagioclase, a mineral commonly found in igneous rocks, is also present in these rocks, according to analysis with Spirit's miniature thermal emission spectrometer. By using the rover's alpha particle X-ray spectrometer to collect data for multiple martian days, or sols, scientists are also beginning to get measurements of trace elements in the rocks. Spirit took the images that are combined into this mosaic on sol 358 (Jan. 3, 2005).

  4. Underground Research Laboratories for Crystalline Rock and Sedimentary Rock in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Shigeta, N.; Takeda, S.; Matsui, H.; Yamasaki, S.

    2003-02-27

    The Japan Nuclear Cycle Development Institute (JNC) has started two off-site (generic) underground research laboratory (URL) projects, one for crystalline rock as a fractured media and the other for sedimentary rock as a porous media. This paper introduces an overview and current status of these projects.

  5. Evaluation of the layering of rock strata and basement rock depth of ...

    African Journals Online (AJOL)

    The layering of rock strata and depth to the basement rocks of a Federal University Teaching Hospital premises in Northern Nigeria was investigated in this study with the aim of providing 2D geo-electrical resistivity images of the subsurface for geotechnical development using a modern and state-of-the-art field instrument, ...

  6. Cecal bacterial communities in wild Japanese rock ptarmigans and captive Svalbard rock ptarmigans.

    Science.gov (United States)

    Ushida, Kazunari; Segawa, Takahiro; Tsuchida, Sayaka; Murata, Koichi

    2016-02-01

    Preservation of indigenous gastrointestinal microbiota is deemed to be critical for successful captive breeding of endangered wild animals, yet its biology is poorly understood. Here, we investigated cecal bacterial communities in wild Japanese rock ptarmigans (Lagopus muta japonica) and compared them with those in Svalbard rock ptarmigans (L. m. hyperborea) in captivity. Ultra-deep sequencing of 16S rRNA gene indicated that the community structure of cecal microbiota in wild rock ptarmigans was remarkably different from that in captive Svalbard rock ptarmigans. Fundamental differences between bacterial communities in the two groups of birds were detected at the phylum level. Firmicutes, Actinobacteria, Bacteroidetes and Synergistetes were the major phyla detected in wild Japanese rock ptarmigans, whereas Firmicutes alone occupied more than 80% of abundance in captive Svalbard rock ptarmigans. Furthermore, unclassified genera of Coriobacteriaceae, Synergistaceae, Bacteroidaceae, Actinomycetaceae, Veillonellaceae and Clostridiales were the major taxa detected in wild individuals, whereas in zoo-reared birds, major genera were Ruminococcus, Blautia, Faecalibacterium and Akkermansia. Zoo-reared birds seemed to lack almost all rock ptarmigan-specific bacteria in their intestine, which may explain the relatively high rate of pathogenic infections affecting them. We show evidence that preservation and reconstitution of indigenous cecal microflora are critical for successful ex situ conservation and future re-introduction plan for the Japanese rock ptarmigan.

  7. THM-coupled modeling of selected processes in argillaceous rock relevant to rock mechanics

    International Nuclear Information System (INIS)

    Czaikowski, Oliver

    2012-01-01

    Scientific investigations in European countries other than Germany concentrate not only on granite formations (Switzerland, Sweden) but also on argillaceous rock formations (France, Switzerland, Belgium) to assess their suitability as host and barrier rock for the final storage of radioactive waste. In Germany, rock salt has been under thorough study as a host rock over the past few decades. According to a study by the German Federal Institute for Geosciences and Natural Resources, however, not only salt deposits but also argillaceous rock deposits are available at relevant depths and of extensions in space which make final storage of high-level radioactive waste basically possible in Germany. Equally qualified findings about the suitability/unsuitability of non-saline rock formations require fundamental studies to be conducted nationally because of the comparatively low level of knowledge. The article presents basic analyses of coupled mechanical and hydraulic properties of argillaceous rock formations as host rock for a repository. The interaction of various processes is explained on the basis of knowledge derived from laboratory studies, and open problems are deduced. For modeling coupled processes, a simplified analytical computation method is proposed and compared with the results of numerical simulations, and the limits to its application are outlined. (orig.)

  8. Strength Assessment of Broken Rock Postgrouting Reinforcement Based on Initial Broken Rock Quality and Grouting Quality

    Directory of Open Access Journals (Sweden)

    Hongfa Xu

    2017-01-01

    Full Text Available To estimate postgrouting rock mass strength growth is important for engineering design. In this paper, using self-developed indoor pressure-grouting devices, 19 groups of test cubic blocks were made of the different water cement ratio grouting into the broken rock of three kinds of particle sizes. The shear strength parameters of each group under different conditions were tested. Then this paper presents a quantitative calculation method for predicting the strength growth of grouted broken rock. Relational equations were developed to investigate the relationship between the growth rates of uniaxial compressive strength (UCS, absolute value of uniaxial tensile strength (AUTS, internal friction angle, and cohesion for post- to pregrouting broken rock based on Mohr-Coulomb strength criterion. From previous test data, the empirical equation between the growth rate of UCS and the ratio of the initial rock mass UCS to the grout concretion UCS has been determined. The equations of the growth rates of the internal friction coefficient and UCS for grouting broken rock with rock mass rating (RMR and its increment have been established. The calculated results are consistent with the experimental results. These observations are important for engineered design of grouting reinforcement for broken rock mass.

  9. Nitrogen in rock: Occurrences and biogeochemical implications

    Science.gov (United States)

    Holloway, J.M.; Dahlgren, R.A.

    2002-01-01

    There is a growing interest in the role of bedrock in global nitrogen cycling and potential for increased ecosystem sensitivity to human impacts in terrains with elevated background nitrogen concentrations. Nitrogen-bearing rocks are globally distributed and comprise a potentially large pool of nitrogen in nutrient cycling that is frequently neglected because of a lack of routine analytical methods for quantification. Nitrogen in rock originates as organically bound nitrogen associated with sediment, or in thermal waters representing a mixture of sedimentary, mantle, and meteoric sources of nitrogen. Rock nitrogen concentrations range from trace levels (>200 mg N kg -1) in granites to ecologically significant concentrations exceeding 1000 mg N kg -1 in some sedimentary and metasedimentary rocks. Nitrate deposits accumulated in arid and semi-arid regions are also a large potential pool. Nitrogen in rock has a potentially significant impact on localized nitrogen cycles. Elevated nitrogen concentrations in water and soil have been attributed to weathering of bedrock nitrogen. In some environments, nitrogen released from bedrock may contribute to nitrogen saturation of terrestrial ecosystems (more nitrogen available than required by biota). Nitrogen saturation results in leaching of nitrate to surface and groundwaters, and, where soils are formed from ammonium-rich bedrock, the oxidation of ammonium to nitrate may result in soil acidification, inhibiting revegetation in certain ecosystems. Collectively, studies presented in this article reveal that geologic nitrogen may be a large and reactive pool with potential for amplification of human impacts on nitrogen cycling in terrestrial and aquatic ecosystems.

  10. Rock Directed Breaking Under the Impulse Load

    Science.gov (United States)

    Khomeriki, Sergo; Mataradze, Edgar; Chikhradze, Nikoloz; Losaberidze, Marine; Khomeriki, Davit; Shatberashvili, Grigol

    2016-10-01

    In the work the problem of directed chipping of facing stone material by means of managing of explosion process is considered. The technology of the mining of decorative stone by the use of explosion energy means the very rapid transfer of potential energy of elastic deformations to kinetic energy. As a result, the explosion impulse, in the expanse of the inertia of rock massive, does not cause the increase of existing cracks. In the course of explosion, the shock wave is propagated by ultrasonic velocity and in this case the medium parameters (pressure, density, temperature, velocity) increase in spurts. In spite of this fact the all three conservation laws of mechanics remain valid on basis of three laws the equations are derived by which the parameters of shock wave may be defined by means of the rock physical-mechanical properties. The load on the body volume at breaking under explosion acts over very small period of the time. Therefore, stressed-deformed state of the rock was studied when the impulse load acts on the boundary. It was considered that the mining of the blocks of facing stone is performed from the hard rocks. This means that the breaking proceeds in the zone of elastic deformation. In the conditions of mentioned assumptions, the expression of the stress tensor and displacement of vector components initiated by stressed-deformed state in the rock are written.

  11. Phosphate rock costs, prices and resources interaction.

    Science.gov (United States)

    Mew, M C

    2016-01-15

    This article gives the author's views and opinions as someone who has spent his working life analyzing the international phosphate sector as an independent consultant. His career spanned two price hike events in the mid-1970's and in 2008, both of which sparked considerable popular and academic interest concerning adequacy of phosphate rock resources, the impact of rising mining costs and the ability of mankind to feed future populations. An analysis of phosphate rock production costs derived from two major industry studies performed in 1983 and 2013 shows that in nominal terms, global average cash production costs increased by 27% to $38 per tonne fob mine in the 30 year period. In real terms, the global average cost of production has fallen. Despite the lack of upward pressure from increasing costs, phosphate rock market prices have shown two major spikes in the 30 years to 2013, with periods of less volatility in between. These price spike events can be seen to be related to the escalating investment cost required by new mine capacity, and as such can be expected to be repeated in future. As such, phosphate rock price volatility is likely to have more impact on food prices than rising phosphate rock production costs. However, as mining costs rise, recycling of P will also become increasingly driven by economics rather than legislation. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Transient evoked otoacoustic emissions in rock musicians.

    Science.gov (United States)

    Høydal, Erik Harry; Lein Størmer, Carl Christian; Laukli, Einar; Stenklev, Niels Christian

    2017-09-01

    Our focus in this study was the assessment of transient evoked otoacoustic emissions (TEOAEs) in a large group of rock musicians. A further objective was to analyse tinnitus among rock musicians as related to TEOAEs. The study was a cross-sectional survey of rock musicians selected at random. A control group was included at random for comparison. We recruited 111 musicians and a control group of 40 non-musicians. Testing was conducted by using clinical examination, pure tone audiometry, TEOAEs and a questionnaire. TEOAE SNR in the half-octave frequency band centred on 4 kHz was significantly lower bilaterally in musicians than controls. This effect was strongly predicted by age and pure-tone hearing threshold levels in the 3-6 kHz range. Bilateral hearing thresholds were significantly higher at 6 kHz in musicians. Twenty percent of the musicians had permanent tinnitus. There was no association between the TEOAE parameters and permanent tinnitus. Our results suggest an incipient hearing loss at 6 kHz in rock musicians. Loss of TEOAE SNR in the 4 kHz half-octave frequency band was observed, but it was related to higher mean 3-6 kHz hearing thresholds and age. A large proportion of rock musicians have permanent tinnitus.

  13. Footwear in rock climbing: Current practice.

    Science.gov (United States)

    McHenry, R D; Arnold, G P; Wang, W; Abboud, R J

    2015-09-01

    Many rock climbers wear ill-fitting and excessively tight footwear during activity. However, there is insufficient evidence of the extent or harms of this practice. To investigate footwear use in rock climbers with a focus on issues surrounding fit. A cross-sectional study with active rock climbers of over one year of experience completing a survey on their activity and footwear. Additionally, the authors quantified foot and shoe lengths and sizes alongside demographic data. Ill-fitting and excessively tight footwear was found in 55 out of 56 rock climbers. Foot pain during activity was also commonplace in 91% of the climbers. A mean size reduction of almost 4 UK shoe sizes was found between the climbers' street shoe size and that of their climbing footwear using a calibrated foot/shoe ruler. There is an unfortunate association of climbers of higher abilities seeking a tighter shoe fit (pfootwear use amongst rock climbers, further investigation may aim to quantify its impact and seek a solution balancing climbing performance while mitigating foot injury. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Transport of suspended matter through rock formations

    International Nuclear Information System (INIS)

    Wahlig, B.G.

    1980-01-01

    It may be hypothesized that significant quantities of some waste nuclides could be adsorbed on the surfaces of particles suspended in the flowing groundwater and thereby migrate farther or faster than they would in dissolved form. This thesis deals with one aspect of this proposed migration mechanism, the transport of suspended matter through rock formations. A theoretical examination of the forces effecting suspended particles in flowing groundwater indicates that only two interaction energies are likely to be significant compared to the particles' thermal energies. The responsible interactions are van der Waals attraction between the particles and the rock, and electrolytic double-layer repulsion between the atmospheres of ions near the surfaces of the particles and the rock. This theoretical understanding was tested in column flow adsorption experiments using fine kaolin particles as the suspended matter and crushed basalt as the rock medium. The effects of several parameters on kaolin mobility were explored, including the influences of the following: solution ion concentration, solution cation valence, degree of solution oxygen saturation, solution flow velocity, and degree of rock surface ageing. The experimental results indicate that the migration of suspended matter over kilometer distances in the lithosphere is very unlikely unless the average pore size of the conducting mediumis fairly large (> 1mm), or the flow occurs in large fractures

  15. Rock stress measurements in the Grimsel Underground Rock Laboratory and their geological interpretation

    International Nuclear Information System (INIS)

    Braeuer, V.; Heusermann, S.; Pahl, A.

    1989-01-01

    Rock stress is being studied as part of the Swiss-German cooperation between the National Cooperative for the Storage of Radioactive Waste (NAGRA), the Research Centre for Environmental Sciences (GSF), and the Federal Institute for Geosciences and Natural Resources (BGR) in the Grimsel Rock Laboratory in Switzerland. Several methods and various equipment for measuring rock stress have been developed and tested in an approximately 200-m borehole drilled from a gallery at a depth of 450 m. The measurements were made continually during overcoring; the data were recorded and processed in a computer located downhole or outside the borehole. The results of the overcoring tests and of frac tests indicate a principle horizontal stress of 25-40 MPa, directed mainly NW-SE. Detailed geological mapping shows relationships between stress and rock structure. A zone of nearly unfractured rock exhibits an increase in stress and a change in stress direction. (orig.)

  16. The analysis of creep characteristics of the surrounding rock of the carbonaceous rock tunnel based on Singh-Mitchell model

    Science.gov (United States)

    Luo, Junhui; Mi, Decai; Ye, Qiongyao; Deng, Shengqiang; Zeng, Fuquan; Zeng, Yongjun

    2018-01-01

    Carbonaceous rock has the characteristics of easy disintegration, softening, swelling and environmental sensitivity, which belongs to soft surrounding rock, and the deformation during excavation and long-term stability of the surrounding rock of carbonaceous rock tunnel are common problems in the construction of carbonaceous rock tunnel. According to the above, the Monitor and measure the displacement, temperature and osmotic pressure of the surrounding carbonaceous rock of the tunnel of Guangxi Hebai highway. Then it based on the obtaining data to study the creep mechanism of surrounding rock using Singh-Mitchell model and predict the deformation of surrounding rock before the tunnel is operation. The results show that the Singh-Mitchell creep model can effectively analyse and predict the deformation development law of surrounding rock of tunnel without considering temperature and osmotic pressure, it can provide reference for the construction of carbonaceous rock tunnel and the measures to prevent and reinforce it..

  17. ROCK1 and ROCK2 are Required for Non-Small Cell Lung Cancer Anchorage-Independent Growth and Invasion

    OpenAIRE

    Vigil, Dominico; Kim, Tai Young; Plachco, Ana; Garton, Andrew J.; Castaldo, Linda; Pachter, Jonathan A.; Dong, Hanqing; Chen, Xin; Tokar, Brianna; Campbell, Sharon L.; Der, Channing J.

    2012-01-01

    Evidence is emerging that the closely related ROCK1 and ROCK2 serine/threonine kinases support the invasive and metastatic growth of a spectrum of human cancer types. Therefore, inhibitors of ROCK are under preclinical development. However, a key step in their development involves the identification of genetic biomarkers that will predict ROCK inhibitor anti-tumor activity. One identified mechanism for ROCK activation in cancer involves the loss of function of the DLC1 tumor suppressor gene, ...

  18. Neodymium and strontium isotopic stratigraphy of the neo-archean Rio Jacare Sill-Bahia, Brazil and its relation to PGE mineralization

    International Nuclear Information System (INIS)

    Brito, Reinaldo S.C de; Pimentel, Marcio M.; Nilson, Ariplinio A.; Gioia, Simone M

    2001-01-01

    Platinum-Group Elements (PGE) deposition in magma chambers is generally accepted as being triggered by sulphur immiscibility via sulfidasation and/or felsification of magmas. These processes can be related to fractional crystallization, and mixing of batches of magmas, crustal contamination or by the combination of these process. Important isotopic studies have been carried out by many authors such as Lambert (1989) and Marcantonio (1995) in the Stillwater Complex, Kruger and Marsh (1989) and Cawthorn (1996) in the Bushveld Complex. Those works set out to understand the role of isotopic changes in the genesis of PGE deposits from JM and Merensky Reefs, respectively. They attributed those PGE mineralizations to isotopically constrained mixing/contamination episodes associated to subtle changes in steady vertical fractionation trends. This work presents stratigraphycally-plotted Nd and Sr isotopic data together with evidence of mineral and whole rock geochemistry disturbance in smooth fractionations trends of the Rio Jacare Sill. Data interpretation suggest the sill was formed via fractional crystallisation and mixing of at least three magma batches, combined with some degree of host rocks assimilation. Isotopic changes were also related to PGE anomalies associated with transitional facies formed during such mixing episodes (au)

  19. Fractal Analysis of Rock Joint Profiles

    Science.gov (United States)

    Audy, Ondřej; Ficker, Tomáš

    2017-10-01

    Surface reliefs of rock joints are analyzed in geotechnics when shear strength of rocky slopes is estimated. The rock joint profiles actually are self-affine fractal curves and computations of their fractal dimensions require special methods. Many papers devoted to the fractal properties of these profiles were published in the past but only a few of those papers employed a convenient computational method that would have guaranteed a sound value of that dimension. As a consequence, anomalously low dimensions were presented. This contribution deals with two computational modifications that lead to sound fractal dimensions of the self-affine rock joint profiles. These are the modified box-counting method and the modified yard-stick method sometimes called the compass method. Both these methods are frequently applied to self-similar fractal curves but the self-affine profile curves due to their self-affine nature require modified computational procedures implemented in computer programs.

  20. Do Bare Rocks Exist on the Moon?

    Science.gov (United States)

    Allen, Carlton; Bandfield, Joshua; Greenhagen, Benjamin; Hayne, Paul; Leader, Frank; Paige, David

    2017-01-01

    Astronaut surface observations and close-up images at the Apollo and Chang'e 1 landing sites confirm that at least some lunar rocks have no discernable dust cover. However, ALSEP (Apollo Lunar Surface Experiments Package) measurements as well as astronaut and LADEE (Lunar Atmosphere and Dust Environment Explorer) orbital observations and laboratory experiments possibly suggest that a fine fraction of dust is levitated and moves across and above the lunar surface. Over millions of years such dust might be expected to coat all exposed rock surfaces. This study uses thermal modeling, combined with Diviner (a Lunar Reconnaissance Orbiter experiment) orbital lunar eclipse temperature data, to further document the existence of bare rocks on the lunar surface.

  1. Aespoe Hard Rock Laboratory. Annual Report 1993

    International Nuclear Information System (INIS)

    1994-06-01

    The Aespoe Hard Rock Laboratory is being constructed in preparation for the deep geological repository of spent fuel in Sweden. This Annual Report 1993 for the Aespoe Hard Rock Laboratory contains an overview of the work conducted. Present work is focused on verification of pre-investigation methods and development of the detailed investigation methodology. Construction of the facility and investigation of the bedrock are carried out in parallel. As of December 1993, 2760 m of the tunnel had been excavated to a depth of 370 m below the surface. An important and integral part of the work is further refinement of conceptual and numerical models for groundwater flow and radionuclide migration. Detailed plans have been prepared for several experiments to be conducted after the end of the construction work. Eight organizations from seven countries are now participating in the work at the Aespoe Hard Rock Laboratory and are contributing in different ways to the results being achieved

  2. Structure analysis - chiromancy of the rock

    International Nuclear Information System (INIS)

    Huber, A.; Huber, M.

    1989-01-01

    The reader may initially be surprised by a comparison between structure analysis and palmistry which is, in effect, a comparison between a scientific research method on the one hand and art which is equated with magical powers on the other. In the figurative sense, however, these two fields have some points in common which should help us to obtain a first impression of the nature of geological structure analysis. Chiromancy uses the lines and the form of the hand to predict the character and the future of the person in question. In the same way, geologists use rocks and rock forms to obtain information on structure and behaviour of different formations. Structure analysis is a specialised field of geological investigation in which traces of deformation are interpreted as expressions of rockforming forces. This article discusses how and why the character of a rock formation as well as its past, present and even future behaviour can be determined using structure analysis. (author) 11 figs

  3. Continuous distillation of oil-bearing rocks

    Energy Technology Data Exchange (ETDEWEB)

    1923-11-14

    A continuous process of distilling petroleum-bearing, asphaltic, or bituminous rocks to free bitumen is characterized by vaporizing hydrocarbons solid, pasty, or liquid from petroleum-containing asphaltic or bituminous rocks to free bitumen without ever reaching the temperatures at which they can produce decomposition, the necessary heat being furnished by combustion of part of the hydrocarbons of the treated rocks. A furnace for carrying out the process of claim 1 is characterized by consisting of a cavity lined inside with reflector, of variable section and with a throat at the upper part for charging the material to be treated and means for blowing the lower part of the furnace with the air necessary for combustion and inert gas for regulating the combustion and removal of the hydrocarbons.

  4. Effects of atmospheric moisture on rock resistivity.

    Science.gov (United States)

    Alvarez, R.

    1973-01-01

    This study examines the changes in resistivity of rock samples as induced by atmospheric moisture. Experiments were performed on samples of hematitic sandstone, pyrite, and galena. The sandstone underwent a change in resistivity of four orders of magnitude when it was measured in a vacuum of 500 ntorr and in air of 37% relative humidity. Pyrite and galena showed no variations in resistivity when they were measured under the same conditions. These results, plus others obtained elsewhere, indicate that rocks of the resistive type are affected in their electrical properties by atmospheric moisture, whereas rocks of the conductive type are not. The experimental evidence obtained is difficult to reconcile with a model of aqueous electrolytic conduction on the sample surface. It is instead suggested that adsorbed water molecules alter the surface resistivity in a manner similar to that observed in semiconductors and insulators.

  5. Rock-brine chemical interactions. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1982-02-01

    The results of experimental interaction of powdered volcanic rock with aqueous solutions are presented at temperatures from 200 to 400/sup 0/C, 500 to 1000 bars fluid pressure, with reaction durations of approximately 30 days under controlled laboratory conditions. The aim of this research is to develop data on the kinetics and equilibria of rock solution interactions that will provide insight into the complex geochemical processes attending geothermal reservoir development, stimulation, and reinjection. The research was done in the Stanford Hydrothermal Lab using gold cell equipment of the Dickson design. This equipment inverts the solution rock mixture several times a minute to ensure thorough mixing. Solution samples were periodically withdrawn without interruption of the experimental conditions. The data from these experiments suggests a path dependent series of reactions by which geothermal fluids might evolve from meteoric or magmatic sources.

  6. Musical Structure as Narrative in Rock

    Directory of Open Access Journals (Sweden)

    John Fernando Encarnacao

    2011-09-01

    Full Text Available In an attempt to take a fresh look at the analysis of form in rock music, this paper uses Susan McClary’s (2000 idea of ‘quest narrative’ in Western art music as a starting point. While much pop and rock adheres to the basic structure of the establishment of a home territory, episodes or adventures away, and then a return, my study suggests three categories of rock music form that provide alternatives to common combinations of verses, choruses and bridges through which the quest narrative is delivered. Labyrinth forms present more than the usual number of sections to confound our sense of ‘home’, and consequently of ‘quest’. Single-cell forms use repetition to suggest either a kind of stasis or to disrupt our expectations of beginning, middle and end. Immersive forms blur sectional divisions and invite more sensual and participatory responses to the recorded text. With regard to all of these alternative approaches to structure, Judy Lochhead’s (1992 concept of ‘forming’ is called upon to underline rock music forms that unfold as process, rather than map received formal constructs. Central to the argument are a couple of crucial definitions. Following Theodore Gracyk (1996, it is not songs, as such, but particular recordings that constitute rock music texts. Additionally, narrative is understood not in (direct relation to the lyrics of a song, nor in terms of artists’ biographies or the trajectories of musical styles, but considered in terms of musical structure. It is hoped that this outline of non-narrative musical structures in rock may have applications not only to other types of music, but to other time-based art forms.

  7. Geomechanical rock properties of a basaltic volcano

    Directory of Open Access Journals (Sweden)

    Lauren N Schaefer

    2015-06-01

    Full Text Available In volcanic regions, reliable estimates of mechanical properties for specific volcanic events such as cyclic inflation-deflation cycles by magmatic intrusions, thermal stressing, and high temperatures are crucial for building accurate models of volcanic phenomena. This study focuses on the challenge of characterizing volcanic materials for the numerical analyses of such events. To do this, we evaluated the physical (porosity, permeability and mechanical (strength properties of basaltic rocks at Pacaya Volcano (Guatemala through a variety of laboratory experiments, including: room temperature, high temperature (935 °C, and cyclically-loaded uniaxial compressive strength tests on as-collected and thermally-treated rock samples. Knowledge of the material response to such varied stressing conditions is necessary to analyze potential hazards at Pacaya, whose persistent activity has led to 13 evacuations of towns near the volcano since 1987. The rocks show a non-linear relationship between permeability and porosity, which relates to the importance of the crack network connecting the vesicles in these rocks. Here we show that strength not only decreases with porosity and permeability, but also with prolonged stressing (i.e., at lower strain rates and upon cooling. Complimentary tests in which cyclic episodes of thermal or load stressing showed no systematic weakening of the material on the scale of our experiments. Most importantly, we show the extremely heterogeneous nature of volcanic edifices that arise from differences in porosity and permeability of the local lithologies, the limited lateral extent of lava flows, and the scars of previous collapse events. Input of these process-specific rock behaviors into slope stability and deformation models can change the resultant hazard analysis. We anticipate that an increased parameterization of rock properties will improve mitigation power.

  8. Ionization and Corona Discharges from Stressed Rocks

    Science.gov (United States)

    Winnick, M. J.; Kulahci, I.; Cyr, G.; Tregloan-Reed, J.; Freund, F. T.

    2008-12-01

    Pre-earthquake signals have long been observed and documented, though they have not been adequately explained scientifically. These signals include air ionization, occasional flashes of light from the ground, radio frequency emissions, and effects on the ionosphere that occur hours or even days before large earthquakes. The theory that rocks function as p-type semiconductors when deviatoric stresses are applied offers a mechanism for this group of earthquake precursors. When an igneous or high-grade metamorphic rock is subjected to deviatoric stresses, peroxy bonds that exist in the rock's minerals as point defects dissociate, releasing positive hole charge carriers. The positive holes travel by phonon-assisted electron hopping from the stressed into and through the unstressed rock volume and build up a positive surface charge. At sufficiently large electric fields, especially along edges and sharp points of the rock, air molecules become field-ionized, loosing an electron to the rock surface and turning into airborne positive ions. This in turn can lead to corona discharges, which manifest themselves by flashes of light and radio frequency emissions. We applied concentrated stresses to one end of a block of gabbro, 30 x 15 x 10 cm3, inside a shielded Faraday cage and observed positive ion currents through an air gap about 25 cm from the place where the stresses were applied, punctuated by short bursts, accompanied by flashes of light and radio frequency emissions characteristic of a corona discharge. These observations may serve to explain a range of pre-earthquake signals, in particular changes in air conductivity, luminous phenomena, radio frequency noise, and ionospheric perturbations.

  9. Anisotropy effect on strengths of metamorphic rocks

    Directory of Open Access Journals (Sweden)

    Ahmet Özbek

    2018-02-01

    Full Text Available This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern (Çine submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including foliated phyllite, schist, gneiss and marble (calcschist were selected and examined. Discontinuity surveys were made along lines for each rock and evaluated with DIPS program. L-type Schmidt hammer was applied in the directions parallel and perpendicular to foliation during the field study. Several hand samples and rock blocks were collected during the field study for measurements of dry and saturated densities, dry and saturated unit weights and porosity, and for petrographic analysis and strength determination in laboratory. L- and N-type Schmidt hammers were applied in the directions perpendicular (anisotropy angle of 0° and parallel (anisotropy angle of 90° to the foliation on selected blocks of phyllite, schist, gneiss and marble (calcschist. The phyllite and schist have higher porosity and lower density values than the other rocks. However, coarse crystalline gneiss and marble (calcschist have higher rebound values and strengths, and they are classified as strong–very strong rocks. Generally, the rebound values in the direction perpendicular to the foliation are slightly higher than that in the direction parallel to foliation. Rebound values of N-type Schmidt hammer are higher than the L-type values except for phyllite. Sometimes, the rebound values of laboratory and field applications gave different results. This may result from variable local conditions such as minerals differentiation, discontinuities, water content, weathering degree and thickness of foliated structure.

  10. Aespoe Hard Rock Laboratory Annual Report 1999

    International Nuclear Information System (INIS)

    2000-08-01

    The Aespoe Hard Rock Laboratory has been constructed as part of the preparations for the deep geological repository for spent nuclear fuel in Sweden. The Tracer Retention Understanding Experiments are made to gain a better understanding of radionuclide retention in the rock and create confidence in the radionuclide transport models that are intended to be used in the licensing of a deep repository for spent fuel. The TRUE -1 experiment including tests with sorbing radioactive tracers in a single fracture over a distance of about 5 m has been completed. Diffusion and sorption in the rock matrix is the dominant retention mechanism over the time scales of the experiments. The main objective of the TRUE Block Scale Experiment is to increase understanding and our ability to predict tracer transport in a fracture network over spatial scales of 10 to 50 m. In total six boreholes have been drilled into the experimental volume located at the 450 m level. The Long-Term Diffusion Experiment is intended as a complement to the dynamic in-situ experiments and the laboratory experiments performed in the TRUE Programme. Diffusion from a fracture into the rock matrix will be studied in situ. The REX project focuses on the reduction of oxygen in a repository after closure due to reactions with rock minerals and microbial activity. Results show that oxygen is consumed within a few days both for the field and laboratory experiments. A new site for the CHEMLAB experiments was selected and prepared during 1999. All future experiment will be conducted in the J niche at 450 m depth. The Prototype Repository Test is focused on testing and demonstrating repository system function. A full-scale prototype including six deposition holes with canisters with electric heaters surrounded by highly compacted bentonite will be built and instrumented. Characterisation of the rock mass in the area of the Prototype repository is completed and the six deposition holes have been drilled. The Backfill and

  11. "All Yugoslavia Is Dancing Rock and Roll"

    DEFF Research Database (Denmark)

    Jovanovic, Zlatko

    with the arrival of New Wave into the country in the late 1970s. The study is carried through micro-historical analyses of the local rock scenes in the country’s four principal rock centres: Belgrade, Zagreb, Sarajevo and Ljubljana. The scenes are used as empirical platforms for discussing broader issues...... assumption of intertextuality, stressing that a text can only communicate its meaning when situated in relation to other texts, as the meaning always “arises” between texts. The thesis demonstrates that although Socialist Yugoslavia did not advocate creation of a supranational Yugoslav identity, but indeed...

  12. Energy Expenditure in Rock/Pop Drumming

    OpenAIRE

    De La Rue, S; Draper, Stephen B; Potter, Christopher R; Smith, M.

    2013-01-01

    Despite the vigorous nature of rock/pop drumming, there are no precise data on the energy expenditure of this activity. The aim of this study was to quantify the energy cost of rock/pop drumming. Fourteen male drummers (mean +/- SD; age 27 +/- 8 yrs.) completed an incremental drumming test to establish the relationship between energy expenditure and heart rate for this activity and a ramped cycle ergometer test to exhaustion as a criterion measure for peak values (oxygen uptake and heart rate...

  13. Migration of radionuclides in fissured rock

    International Nuclear Information System (INIS)

    Neretnieks, I.

    1982-01-01

    Some computed results of radionuclide migration in fissured rock are presented. The computations are based on a model which describes flow as occurring in a multitude of independent fissures (stratified flow). This gives rise to strong dispersion of channeling. The radionuclide migration in the individual fissures is modelled by the advection equation on a parallel walled channel with porous walls. The nuclides may diffuse into the pores and sorb reversibly on the pore surfaces. The effluent rates of 23 important nuclides are presented as functions of distance and time for various of important parameters such as rock permeability, diffusion coefficients, release rates, time of first release, fissure spacing and fissure width distribution. (Author)

  14. Aespoe Hard Rock Laboratory Annual Report 1999

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-08-01

    The Aespoe Hard Rock Laboratory has been constructed as part of the preparations for the deep geological repository for spent nuclear fuel in Sweden. The Tracer Retention Understanding Experiments are made to gain a better understanding of radionuclide retention in the rock and create confidence in the radionuclide transport models that are intended to be used in the licensing of a deep repository for spent fuel. The TRUE -1 experiment including tests with sorbing radioactive tracers in a single fracture over a distance of about 5 m has been completed. Diffusion and sorption in the rock matrix is the dominant retention mechanism over the time scales of the experiments. The main objective of the TRUE Block Scale Experiment is to increase understanding and our ability to predict tracer transport in a fracture network over spatial scales of 10 to 50 m. In total six boreholes have been drilled into the experimental volume located at the 450 m level. The Long-Term Diffusion Experiment is intended as a complement to the dynamic in-situ experiments and the laboratory experiments performed in the TRUE Programme. Diffusion from a fracture into the rock matrix will be studied in situ. The REX project focuses on the reduction of oxygen in a repository after closure due to reactions with rock minerals and microbial activity. Results show that oxygen is consumed within a few days both for the field and laboratory experiments. A new site for the CHEMLAB experiments was selected and prepared during 1999. All future experiment will be conducted in the J niche at 450 m depth. The Prototype Repository Test is focused on testing and demonstrating repository system function. A full-scale prototype including six deposition holes with canisters with electric heaters surrounded by highly compacted bentonite will be built and instrumented. Characterisation of the rock mass in the area of the Prototype repository is completed and the six deposition holes have been drilled. The Backfill and

  15. Petrological studies of plutonic rocks of Ecuador

    International Nuclear Information System (INIS)

    Aly, S.

    1980-01-01

    The feldspars of many tonalitic plutonic rocks in the coastal regions and West Andean regions are zoned. This leads to the conclusion that they are relatively flat intrusions and to some extent transition rocks in the subvulcanite direction. This is in accordance with the genetic and chronological relationship between plutonites and the surrounding vulcanites of the Basic Igreous Complex (BIC). The composition of representative minerals, e.g. alkali feldspar, plagioclase feldspar, biotite, chlorite, and amphibole has been determined as well as the age of plutonite samples by the K/Ar dating method. (DG) [de

  16. Optically stimulated luminescence dating of rock surfaces

    DEFF Research Database (Denmark)

    Sohbati, Reza

    There are many examples of rock surfaces, rock art and stone structures whose ages are of great importance to the understanding of various phenomena in geology, climatology and archaeology. Optically stimulated luminescence (OSL) dating is a well-established chronological tool that has successfully...... to include the effects of the environmental dose rate. By fitting the model to the dose-depth variation from a single clast, four events (two light exposures of different durations each followed by a burial period) in the history of a single cobble are identified and quantified. However, the use of model...

  17. Rock support for nuclear waste repositories

    International Nuclear Information System (INIS)

    Abramson, L.W.; Schmidt, B.

    1984-01-01

    The design of rock support for underground nuclear waste repositories requires consideration of special construction and operation requirements, and of the adverse environmental conditions in which some of the support is placed. While repository layouts resemble mines, design, construction and operation are subject to quality assurance and public scrutiny similar to what is experienced for nuclear power plants. Exploration, design, construction and operation go through phases of review and licensing by government agencies as repositories evolve. This paper discusses (1) the various stages of repository development; (2) the environment that supports must be designed for; (3) the environmental effects on support materials; and (4) alternative types of repository rock support

  18. Integration of rock typing methods for carbonate reservoir characterization

    International Nuclear Information System (INIS)

    Aliakbardoust, E; Rahimpour-Bonab, H

    2013-01-01

    Reservoir rock typing is the most important part of all reservoir modelling. For integrated reservoir rock typing, static and dynamic properties need to be combined, but sometimes these two are incompatible. The failure is due to the misunderstanding of the crucial parameters that control the dynamic behaviour of the reservoir rock and thus selecting inappropriate methods for defining static rock types. In this study, rock types were defined by combining the SCAL data with the rock properties, particularly rock fabric and pore types. First, air-displacing-water capillary pressure curues were classified because they are representative of fluid saturation and behaviour under capillary forces. Next the most important rock properties which control the fluid flow and saturation behaviour (rock fabric and pore types) were combined with defined classes. Corresponding petrophysical properties were also attributed to reservoir rock types and eventually, defined rock types were compared with relative permeability curves. This study focused on representing the importance of the pore system, specifically pore types in fluid saturation and entrapment in the reservoir rock. The most common tests in static rock typing, such as electrofacies analysis and porosity–permeability correlation, were carried out and the results indicate that these are not appropriate approaches for reservoir rock typing in carbonate reservoirs with a complicated pore system. (paper)

  19. Water-rock interaction in a high-FeO olivine rock in nature

    International Nuclear Information System (INIS)

    Hellmuth, K.H.; Lindberg, A.; Tullborg, E.L.

    1992-12-01

    The long-term behaviour in nature of high-FeO olivine rock in contact with surface water has been studied at the Lovasjaervi instrusion, SE-Finland. The rock has been proposed as a high-capasity, higly reactive redox-buffer backfill in a repository for spent fuel. Favourable groundwater chemistry is a major parameter relevant to safety of such a repository. Reducing conditions favour the retardation of long-lived, redox-sensitive radionuclides. Weathering influences have been studied at the natural outcrop of the rock mass. The interaction of oxidizing surface waters with rock at greater depths has been studied by using fissure filling minerals. Investigation of weathered rock from the outcrop indicates that the olivine rock is highly reactive on a geological time scale and its redox capasity is available although the instrusion as a whole is surprisingly well preserved. The fissure fillings studied allow the conclusion that oxygen seems to be efficiently removed from intruding surface water. Oxidation seem to have caused visible effects only along very conducting fractures and near the contact zones of the surrounding granitic rock. Stable isotope data of fissure filling calcites indicate that the influence of surface waters can be traced clearly down to a depth of about 50 m, but also at greater depths re-equilibration has occurred. Groundwater data from the site were not available. (orig.)

  20. Interim rock mass properties and conditions for analyses of a repository in crystalline rock

    International Nuclear Information System (INIS)

    Tammemagi, H.Y.; Chieslar, J.D.

    1985-03-01

    A summary of rock properties for generic crystalline rock is compiled from literature sources to provide the input data for analyses of a conceptual repository in crystalline rock. Frequency histograms, mean values and ranges of physical, mechanical, thermal, and thermomechanical properties, and the dependence of these properties on temperature are described. A description of the hydrogeologic properties of a crystalline rock mass and their dependence on depth is provided. In addition, the temperature gradients, mean annual surface temperature, and in situ stress conditions are summarized for the three regions of the United States currently under consideration to host a crystalline repository; i.e., the North Central, Northeastern, and Southeastern. Brief descriptions of the regional geology are also presented. Large-scale underground experiments in crystalline rock at Stripa, Sweden, and in Climax Stock in Nevada, are reviewed to assess whether the rock properties presented in this report are representative of in situ conditions. The suitability of each rock property and the sufficiency of its data base are described. 110 refs., 27 figs., 4 tabs

  1. Bioremediation in Fractured Rock: 2. Mobilization of Chloroethene Compounds from the Rock Matrix.

    Science.gov (United States)

    Shapiro, Allen M; Tiedeman, Claire R; Imbrigiotta, Thomas E; Goode, Daniel J; Hsieh, Paul A; Lacombe, Pierre J; DeFlaun, Mary F; Drew, Scott R; Curtis, Gary P

    2018-03-01

    A mass balance is formulated to evaluate the mobilization of chlorinated ethene compounds (CE) from the rock matrix of a fractured mudstone aquifer under pre- and postbioremediation conditions. The analysis relies on a sparse number of monitoring locations and is constrained by a detailed description of the groundwater flow regime. Groundwater flow modeling developed under the site characterization identified groundwater fluxes to formulate the CE mass balance in the rock volume exposed to the injected remediation amendments. Differences in the CE fluxes into and out of the rock volume identify the total CE mobilized from diffusion, desorption, and nonaqueous phase liquid dissolution under pre- and postinjection conditions. The initial CE mass in the rock matrix prior to remediation is estimated using analyses of CE in rock core. The CE mass mobilized per year under preinjection conditions is small relative to the total CE mass in the rock, indicating that current pump-and-treat and natural attenuation conditions are likely to require hundreds of years to achieve groundwater concentrations that meet regulatory guidelines. The postinjection CE mobilization rate increased by approximately an order of magnitude over the 5 years of monitoring after the amendment injection. This rate is likely to decrease and additional remediation applications over several decades would still be needed to reduce CE mass in the rock matrix to levels where groundwater concentrations in fractures achieve regulatory standards. © 2017, National Ground Water Association.

  2. Bioremediation in fractured rock: 2. Mobilization of chloroethene compounds from the rock matrix

    Science.gov (United States)

    Shapiro, Allen M.; Tiedeman, Claire; Imbrigiotta, Thomas; Goode, Daniel J.; Hsieh, Paul A.; Lacombe, Pierre; DeFlaun, Mary F.; Drew, Scott R.; Curtis, Gary P.

    2018-01-01

    A mass balance is formulated to evaluate the mobilization of chlorinated ethene compounds (CE) from the rock matrix of a fractured mudstone aquifer under pre- and postbioremediation conditions. The analysis relies on a sparse number of monitoring locations and is constrained by a detailed description of the groundwater flow regime. Groundwater flow modeling developed under the site characterization identified groundwater fluxes to formulate the CE mass balance in the rock volume exposed to the injected remediation amendments. Differences in the CE fluxes into and out of the rock volume identify the total CE mobilized from diffusion, desorption, and nonaqueous phase liquid dissolution under pre- and postinjection conditions. The initial CE mass in the rock matrix prior to remediation is estimated using analyses of CE in rock core. The CE mass mobilized per year under preinjection conditions is small relative to the total CE mass in the rock, indicating that current pump-and-treat and natural attenuation conditions are likely to require hundreds of years to achieve groundwater concentrations that meet regulatory guidelines. The postinjection CE mobilization rate increased by approximately an order of magnitude over the 5 years of monitoring after the amendment injection. This rate is likely to decrease and additional remediation applications over several decades would still be needed to reduce CE mass in the rock matrix to levels where groundwater concentrations in fractures achieve regulatory standards.

  3. Theoretical study of rock mass investigation efficiency

    International Nuclear Information System (INIS)

    Holmen, Johan G.; Outters, Nils

    2002-05-01

    The study concerns a mathematical modelling of a fractured rock mass and its investigations by use of theoretical boreholes and rock surfaces, with the purpose of analysing the efficiency (precision) of such investigations and determine the amount of investigations necessary to obtain reliable estimations of the structural-geological parameters of the studied rock mass. The study is not about estimating suitable sample sizes to be used in site investigations.The purpose of the study is to analyse the amount of information necessary for deriving estimates of the geological parameters studied, within defined confidence intervals and confidence level In other words, how the confidence in models of the rock mass (considering a selected number of parameters) will change with amount of information collected form boreholes and surfaces. The study is limited to a selected number of geometrical structural-geological parameters: Fracture orientation: mean direction and dispersion (Fisher Kappa and SRI). Different measures of fracture density (P10, P21 and P32). Fracture trace-length and strike distributions as seen on horizontal windows. A numerical Discrete Fracture Network (DFN) was used for representation of a fractured rock mass. The DFN-model was primarily based on the properties of an actual fracture network investigated at the Aespoe Hard Rock Laboratory. The rock mass studied (DFN-model) contained three different fracture sets with different orientations and fracture densities. The rock unit studied was statistically homogeneous. The study includes a limited sensitivity analysis of the properties of the DFN-model. The study is a theoretical and computer-based comparison between samples of fracture properties of a theoretical rock unit and the known true properties of the same unit. The samples are derived from numerically generated boreholes and surfaces that intersect the DFN-network. Two different boreholes are analysed; a vertical borehole and a borehole that is

  4. Distribution of Pa-231 and Ra-226 in rock. An indicator of rock matrix diffusion

    International Nuclear Information System (INIS)

    Saarinen, L.; Suksi, J.

    1995-01-01

    Distribution of Ra-226 and Pa-231 in rock has been studied to find signatures that may be attributed to diffusion. The idea of studying these nuclides originated from the need to obtain interpretative support to the findings of U movement in rock. Concentration profiles of Ra-226 and Pa-231 with other U series nuclides were measured across the secondary U accumulations observed in altered rock close to a fracture in the vicinity of U deposit, and in a radioactivity anomaly. (27 refs., 10 figs., 2 tabs.)

  5. Initial settlements of rock fills on soft clay

    OpenAIRE

    Pedersen, Truls Martens

    2012-01-01

    Rock fills that hit the seabed will remold the underlying material. If this material is a clay with sufficiently low shear strength, it will adopt rheological properties, causing flow through the rock fill, and contributing to the initial settlements of the rock fill in addition to conventional consolidation theory. The settlements of the rocks depend upon the height of the rock fill and how the rocks have been laid out. This is due to the viscosity of the clay, and the fact that clay is thix...

  6. Waste-rock interactions and bedrock reactions

    International Nuclear Information System (INIS)

    White, W.B.

    1977-01-01

    The experimental program is designed to discover possible reactions between shale repository rocks and radioactive wastes. The canister can be regarded in three ways: (a) As a source of heat that modifies the mineralogy and therefore the physical properties of the surrounding rock (dry heat). (b) As a source of heat that activates reactions between minerals in the surrounding rock and slowly percolating ground water. (c) As a source of reaction materials of different composition from the surrounding rock and which therefore may react to form completely new ''minerals'' in a contact aureole around the canister. The matrix of interactions contains two composition axes. The waste compositions are defined by the various prototype waste forms usually investigated: glass, calcine, ''spent fuel'' and the ceramic supercalcine. The temperatures and pressures at which these reactions take place must be investigated. Thus each node on the ''wiring diagram'' is itself a matrix of experiments in which the T and to some extent P are varied. Experiments at higher pressure and temperature allow reactions to take place on a laboratory time scale and thus identify what could happen. These reactions are then followed downward in temperature to determine both phase boundaries and kinetic cut-offs below which equilibrium cannot be achieved on a laboratory time scale

  7. Waste package performance in unsaturated rock

    International Nuclear Information System (INIS)

    Pigford, T.H.; Lee, W.W.-L.

    1989-03-01

    The unsaturated rock and near-atmospheric pressure of the potential nuclear waste repository at Yucca Mountain present new problems of predicting waste package performance. In this paper we present some illustrations of predictions of waste package performance and discuss important data needs. 11 refs., 9 figs., 1 tab

  8. Modeling rock weathering in small watersheds

    NARCIS (Netherlands)

    Pacheco, F.A.L.; van der Weijden, C.H.

    2014-01-01

    Many mountainous watersheds are conceived as aquifer media where multiple groundwater flow systems have developed (Tóth, 1963), and as bimodal landscapes where differential weathering of bare and soil-mantled rock has occurred (Wahrhaftig, 1965). The results of a weathering algorithm (Pacheco and

  9. O rock desligado de Lóki

    Directory of Open Access Journals (Sweden)

    Márcia Carvalho

    2012-08-01

    Full Text Available This paper presents an analysis of the documentary Loki: ArnaldoBaptista (2009, direct by Paulo Henrique Fontenelle. This analysis investigates thehistorical research and biographical approach, examining in particular the enhancement oforal memory and musical performances from different sources to put into perspective thehistory of Brazilian rock on movie screens and television.

  10. Palynofacies characterization for hydrocarbon source rock ...

    Indian Academy of Sciences (India)

    source rock potential of the Subathu Formation in the area. Petroleum geologists are well aware of the fact that the dispersed organic matter derived either from marine or non-marine sediments on reach- ing its maturation level over extended period of time contributes as source material for the produc- tion of hydrocarbons.

  11. Contemporary Art and Rock, some relations

    Directory of Open Access Journals (Sweden)

    Leonardo Felipe

    2011-12-01

    Full Text Available This article investigates some relations between contemporary art and rock, from a collection of examples of the involvement between artists and rockers through history. Notably Pop Art, punk, Conceptual Art and the figure of Hélio Oiticica. The article detaches geographical aspects in this relation, with special attention to the New York and London scenes between 1960-1980.

  12. Uncertainty in hydraulic tests in fractured rock

    International Nuclear Information System (INIS)

    Ji, Sung-Hoon; Koh, Yong-Kwon

    2014-01-01

    Interpretation of hydraulic tests in fractured rock has uncertainty because of the different hydraulic properties of a fractured rock to a porous medium. In this study, we reviewed several interesting phenomena which show uncertainty in a hydraulic test at a fractured rock and discussed their origins and the how they should be considered during site characterisation. Our results show that the estimated hydraulic parameters of a fractured rock from a hydraulic test are associated with uncertainty due to the changed aperture and non-linear groundwater flow during the test. Although the magnitude of these two uncertainties is site-dependent, the results suggest that it is recommended to conduct a hydraulic test with a little disturbance from the natural groundwater flow to consider their uncertainty. Other effects reported from laboratory and numerical experiments such as the trapping zone effect (Boutt, 2006) and the slip condition effect (Lee, 2014) can also introduce uncertainty to a hydraulic test, which should be evaluated in a field test. It is necessary to consider the way how to evaluate the uncertainty in the hydraulic property during the site characterisation and how to apply it to the safety assessment of a subsurface repository. (authors)

  13. Ore potential of basic rocks in Finland

    International Nuclear Information System (INIS)

    Reino, J.; Ekberg, M.; Heinonen, P.; Karppanen, T.; Hakapaeae, A.; Sandberg, E.

    1993-02-01

    The report is associated with a study programme on basic rocks, which has the aim to complement the preliminary site investigations on repository for TVO's (Teollisuuden Voima Oy) spent nuclear fuel. The report comprises a mining enterprise's view of the ore potential of basic plutonic rocks in Finland. The ores associated with basic plutonic rocks are globally known and constitute a significant share of the global mining industry. The ores comprise chromium, vanadium-titanium-iron, nickel-copper and platinum group element ores. The resources of the metals in question and their mining industry are examined globally. A review of the use of these metals in the industry is presented as well. General factors affecting the mining industry, such as metal prices, political conjunctures, transport facilities, environmental requirements and raw material sources for the Finnish smelters have been observed from the point of view of their future effect on exploration activity and industrial development in Finland. Information on ores and mineralizations associated with Finnish basic rocks have been compiled in the report. The file comprises 4 chromium occurrences, 8 vanadium-titanium-iron occurrences, 13 PGE occurrences and 38 nickel-copper occurrences

  14. Fluorine geochemistry in volcanic rock series

    DEFF Research Database (Denmark)

    Stecher, Ole

    1998-01-01

    A new analytical procedure has been established in order to determine low fluorine concentrations (30–100 ppm F) in igneous rocks, and the method has also proven successful for higher concentrations (100–4000 ppm F). Fluorine has been measured in a series of olivine tholeiites from the Reykjanes ...

  15. Transmission Electron Microscopy of Minerals and Rocks

    Science.gov (United States)

    McLaren, Alex C.

    1991-04-01

    Of the many techniques that have been applied to the study of crystal defects, none has contributed more to our understanding of their nature and influence on the physical and chemical properties of crystalline materials than transmission electron microscopy (TEM). TEM is now used extensively by an increasing number of earth scientists for direct observation of defect microstructures in minerals and rocks. Transmission Electron Microscopy of Rocks and Minerals is an introduction to the principles of the technique and is the only book to date on the subject written specifically for geologists and mineralogists. The first part of the book deals with the essential physics of the transmission electron microscope and presents the basic theoretical background required for the interpretation of images and electron diffraction patterns. The final chapters are concerned with specific applications of TEM in mineralogy and deal with such topics as planar defects, intergrowths, radiation-induced defects, dislocations and deformation-induced microstructures. The examples cover a wide range of rock-forming minerals from crustal rocks to those in the lower mantle, and also take into account the role of defects in important mineralogical and geological processes.

  16. The riddles of rock and roll

    NARCIS (Netherlands)

    L.J.M. d' Anjou (Leo)

    2003-01-01

    textabstractRock and roll has often been equated with rebellion. The genre, though, is just a form of popular music and many of the important players in the game of promoting it were, like the saying goes, only in it for the money. As a rule, music like that will be supportive of the social order

  17. Fractures and Rock Mechanics, Phase 1

    DEFF Research Database (Denmark)

    Krogsbøll, Anette; Jakobsen, Finn; Madsen, Lena

    1997-01-01

    The main objective of the project is to combine geological descriptions of fractures, chalk types and rock mechanical properties in order to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. This report deals with 1) geological descriptions of outcrop locality...

  18. Fractures and Rock Mechanics, Phase 1

    DEFF Research Database (Denmark)

    Havmøller, Ole; Krogsbøll, Anette

    1997-01-01

    The main objectives of the project are to combine geological description of fractures, chalk types and rock mechanical properties, and to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. Five chalk types, representing two outcrop localities: Stevns...

  19. Palaeomagnetism or Palaeomagic? Misconceptions about Rock Magnetism

    Science.gov (United States)

    Murphy, Phil

    2016-01-01

    The study and understanding of paleomagnetism has been pivotal in the development of the theory of plate tectonics. When it is taught in schools there are a number possible misconceptions that need to be addressed. This article attempts to provide an explanation of rock magnetism as well as strategies to avoid reinforcing some commonly identified…

  20. Crowdsourcing rock n' roll multimedia retrieval

    NARCIS (Netherlands)

    Snoek, Cees G.M.; Freiburg, Bauke; Oomen, Johan; Ordelman, Roeland J.F.

    2010-01-01

    In this technical demonstration, we showcase a multimedia search engine that facilitates semantic access to archival rock n' roll concert video. The key novelty is the crowdsourcing mechanism, which relies on online users to improve, extend, and share, automatically detected results in video