WorldWideScience

Sample records for re-os isotopic dating

  1. Re-Os isotopic system and formation age of subcontinental lithosphere mantle

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The determination of the formation age of subcontinental Lithosphere Mantle (SCLM) is a widely concerned issue in mantle geochemistry. It is difficult to obtain the formation age of SCLM using lithophile isotopic systems such as Rb-Sr, Sm-Nd, U-Th-Pb, etc., but as siderophile elements, the Re-Os isotopic system provides a powerful tool for that work. Here a comprehensive review on the recent development in Re-Os dating for SCLM has been given.

  2. Re-Os dating of pyrite from Giant Bayan Obo REE-Nb-Fe deposit

    Institute of Scientific and Technical Information of China (English)

    LIU Yulong; YANG Gang; CHEN Jiangfeng; DU Andao; XIE Zhi

    2004-01-01

    Six pyrite samples from the giant Bayan Obo REE-Nb-Fe deposit are dated by Re-Os technique. Pyrite studied is associated with barite and separated from a vein cutting REE mineralization. Pyrites analyzed contain 16-30 ng Re and 0.10-0.16 ng Os, and yield a Caledonian isochron age of 439 ± 86 Ma. High Re/Os ratio, low Os concentration and highly radiogenic Os isotopic ratios of these samples suggest that they are of crustal origin. The northern margin of the North China Block was a passive continental margin, but not a subduction zone with enormous volcanic activities in the Early Paleozoic Era. Our Re-Os result provides new evidences, showing that Bayan Obo deposit experienced a thermal disturbance of crustal origin in the Caledonian time and some isotopic systems recorded only the time of the disturbance, not the mineralization age.

  3. Cu-Mo-Au mineralization in Qarachilar area, Qaradagh batholith (NW Iran): Fluid inclusion and stable isotope studies and Re-Os dating

    Science.gov (United States)

    Simmonds, Vartan; Moazzen, Mohssen

    2015-04-01

    The Qaradagh batholith is located in NW Iran, neighboring the Meghri-Ordubad granitoid in southern Armenia. This magmatic complex is emplaced in the northwestern part of the Urumieh-Dokhtar magmatic arc, which formed through north-eastward subduction of Neo-Tethyan oceanic crust beneath the central Iranian domain in the late-Mesozoic and early-Cenozoic and hosts most of the porphyry copper deposits and prospects in Iran, such as Sarcheshmeh and Sungun. The Qaradagh batholith is comprised of Eocene-Oligocene intrusive rocks occurring as multi-episode stocks, where the dominant rock type is granodiorite. Hydrothermal alterations have also occurred in these rocks including potassic, phyllic-sericitic, argillic and propylitic alterations and silicification. These alterations are accompanied by vein-type and disseminated Cu, Mo and Au mineralization. The Qarachilar area is located in the central part of the Qaradagh batholith, which hosts mono-mineralic and quartz-sulfide veins and veinlets (several mm to hydrothermal aqueous fluids have most likely experienced boiling and also mixed with low temperature and low salinity superficial fluids. Occurrence of boiling is also supported by the coexistence of liquid-rich and vapor-rich 2-phase inclusions as well as multi-phase halite-bearing inclusions which homogenize in a similar range of TH. The calculated minimum pressure at the time of entrapment is estimated about 50 to 120 bar, which is equal to the hydrostatic depth of 500-1100 m. Stable isotope studies of O, H and S on the quartz and sulfide samples taken from quartz-sulfide veins-veinlets reveal a magmatic origin for the ore-bearing fluid and its sulfur content. The δ18O values for quartz and fluid are about 11.13-12.47 ‰ and 5.78-6.89 ‰ (SMOW), respectively, the δD values are about -93 and -50 ‰ and the δ34S values of sulfide minerals are about -1.37-0.49‰ (VCDT). Re-Os model ages calculated for molybdenite samples range between 25.19±0.19 and 31.22±0

  4. Preparation and certification of Re-Os dating reference materials: Molybdenites HLP and JDC

    Science.gov (United States)

    Du, A.; Wu, S.; Sun, D.; Wang, Shaoming; Qu, W.; Markey, R.; Stain, H.; Morgan, J.; Malinovskiy, D.

    2004-01-01

    Two Re-Os dating reference material molybdenites were prepared. Molybdenite JDC and molybdenite HLP are from a carbonate vein-type molybdenum-(lead)- uranium deposit in the Jinduicheng-Huanglongpu area of Shaanxi province, China. The samples proved to be homogeneous, based on the coefficient of variation of analytical results and an analysis of variance test. The sampling weight was 0.1 g for JDC and 0.025 g for HLP. An isotope dilution method was used for the determination of Re and Os. Sample decomposition and preconcentration of Re and Os prior to measurement were accomplished using a variety of methods: acid digestion, alkali fusion, ion exchange and solvent extraction. Negative thermal ionisation mass spectrometry and inductively coupled plasma-mass spectrometry were used for the determination of Re and 187Os concentration and isotope ratios. The certified values include the contents of Re and Os and the model ages. For HLP, the Re content was 283.8 ?? 6.2 ??g g-1, 187Os was 659 ?? 14 ng g-1 and the Re-Os model age was 221.4 ?? 5.6 Ma. For JDC, the Re content was 17.39 ?? 0.32 ng g-1, 187Os was 25.46 ?? 0.60 ng g-1 and the Re-Os model age was 139.6 ?? 3.8 Ma. Uncertainties for both certified reference materials are stated at the 95% level of confidence. Three laboratories (from three countries: P.R. China, USA, Sweden) joined in the certification programme. These certified reference materials are primarily useful for Re-Os dating of molybdenite, sulfides, black shale, etc.

  5. 内蒙古白乃庙铜(钼)矿床辉钼矿Re Os 同位素年龄及其地质意义%Re Os Isotopic Dating of Molybdenite from the Bainaimiao Cu(Mo) Deposit in Inner Mongolia and Its Geological Significance

    Institute of Scientific and Technical Information of China (English)

    冯晓曦; 姚书振; 段明; 曲凯; 王佳营; 冯旭彪; 李超; 周利敏

    2015-01-01

    The Bainaimiao Cu(Mo)deposit is the most important ones in the north margin of North China plate.It is composed of south belt and north belt.In south belt,ore bodies are concordant with ore-hosting green schist of the Cambrain Bainaimiao Formation,with near-bedded and lenticular shapes, the major bodies in north belt are located in granodiorite intrusion and partly extending into host rocks. The metallogenic age of this deposit has been disputed for many years.To dtermine the minerlization age,Re Os isotopic dating of five molybdenite samples,separated from both south and north ore belt, are completed,five molybdenite samples yield isotopic model ages of (435.8±6.0)Ma to (443.0±6.1) Ma,and an isochron age of (440.5±4.4)Ma (2σ,MSWD=1.4).These ages are well concordant with the emplacement age (440.0 Ma)of the granodiorite.Combining with regional geological background and deposit characteristics,authors think synthetically that the deposit formed in Early Silurian and has close relationship with granodioritic (440.0 Ma ) magmatic activities in Early Silurian. The mineralization age is also consist with the period (446.0 453.0 Ma)of the intensive southward subduction of the paleo-Asian oceanic plate beneath to the northern margin of the North China plate.By synthetical analysis,authors conclude that the major metallogenetic event were resulted from the evolution of the trech-basin-arc system and continent margin accretion in the North China plate during the Early Paleozoic epoch.%内蒙古白乃庙铜(钼)矿床是华北板块北缘中段最重要的一个铜(钼)矿床,矿床由南、北两矿带构成。南矿带矿体主要产于寒武系白乃庙组绿片岩中,矿体产状与围岩基本一致;北矿带矿体大部分产于花岗闪长岩体中,部分延进围岩。利用 Re Os 同位素定年方法对南、北矿带主要矿段的5件辉钼矿样品进行了成矿时代研究,结果表明,辉钼矿样品的 Re Os 同位素模式年龄为(435.8±6

  6. Re-Os dating of sulphide inclusions zonally distributed in single Yakutian diamonds: Evidence for multiple episodes of Proterozoic formation and protracted timescales of diamond growth

    Science.gov (United States)

    Wiggers de Vries, D. F.; Pearson, D. G.; Bulanova, G. P.; Smelov, A. P.; Pavlushin, A. D.; Davies, G. R.

    2013-11-01

    The timing of diamond formation in the Siberian lithospheric mantle was investigated by Re-Os isotope dating of sulphide inclusions from eclogitic and lherzolitic diamonds from the Mir, 23rd Party Congress and Udachnaya kimberlite pipes in Yakutia. The diamonds contained multiple sulphide inclusions distributed over their core-to-rim zones. Cathodoluminescence, carbon isotope and nitrogen aggregation studies demonstrate that the diamonds are zoned and that the distinct zones are associated with different diamond growth episodes. There are coherent relationships between carbon isotope composition, nitrogen concentration and aggregation state of the diamond hosts, and major and trace element compositions, Re-Os compositions and initial Os isotope ratios of the included sulphides. This suggests that the different diamond and sulphide populations formed at different times from fluids/melts with different chemical compositions. Based on the Re-Os isochron ages and the nitrogen aggregation states we conclude that the sulphides are co-genetic with their diamond hosts.

  7. Re-Os isotope geochemistry of three Chinese chondrites

    Institute of Scientific and Technical Information of China (English)

    ZHI XiaChen; QIN Xie; SHI RenDeng; HONG JiAn

    2007-01-01

    Three Chinese ordinary chondrites, including Jilin (H5), Boxian (LL3.8) and Lujiang (LL6), have been studied for their Re and Os abundances and Os isotopic composition in whole-chondrite samples, separated magnetic and nonmagnetic fractions, and nodules.The results indicate that the Re and Os abundances of the whole-chondrite samples are in the ranges of corresponding H- and LL-Groups, respectively.The Re and Os abundances of magnetic fraction from Boxian and Lujiang are within the range of high-Os IIAB and IIIAB irons, whereas those of nonmagnetic fractions of Boxian and Lujiang are lower than the whole-chondrite values.The Re and Os abundances of nodules in Jilin are in the range of the LL-Group.187Re/188Os and 187Os/188Os ratios of the three whole chondrites are in the range of ordinary chondrites which locate around the isochron of IIAB+IIIAB irons.187Re/188Os and 187Os/188Os ratios of the magnetic and nonmagnetic fractions from Boxian have a larger difference.The nonmagnetic fraction of Lujiang may contain a recent addition of Re, which causes deviation of the 187Re/188Os ratio from the irons isochron.The Re and Os abundances of nodules in Jilin are lower than those of the whole-chondrite, but their 187Os/188Os ratios are higher than that of the whole chondrite.

  8. Re-Os Isotopes Distinguish Crust vs. Slab Inputs to Northern Cascade Arc Basalts

    Science.gov (United States)

    Mullen, E.; Gannoun, A.; Nauret, F.; Schiano, P.; Weis, D.

    2015-12-01

    Delineating the relative contributions of mantle, slab, and crust to arc magmas is particularly challenging in the Cascades where the continental crust is juvenile and contrasts little with magmas in traditional radiogenic isotope systems (Sr-Nd-Hf-Pb). The Re-Os isotope system offers a sensitive technique for evaluating these contributions because even young crust has significantly higher Os ratios than the mantle. We analyzed Re-Os isotope ratios in 33 primitive basalts from 9 volcanic centers of the northern Cascade Arc (Garibaldi Volcanic Belt, GVB). Although GVB basalts have mantle-like Sr-Pb-Nd-Hf ratios (Mullen & Weis, 2015, EPSL), the range in 187Os/188Os is very large (0.13-0.99) with [Os] of Cinder Cone/Mt. Garibaldi, Salal Glacier, Mt. Meager, Indian Pass/Glacier Peak) has low Os isotopic ratios (0.13-0.19), only slightly elevated relative to global mantle wedge peridotites (≤0.16), indicating minimal crustal contamination. Group 1 samples lie on Os-Sr isotope mixing curves indicating variable sediment input to the mantle. Os ratios of Group 2 basalts (Silverthrone, Bridge River, Elaho, Cheakamus, Mt. Baker, Glacier Peak) extend to extremely high values, up to 0.99, and lie on different Os-Sr mixing curves indicating addition of a crustal contaminant. Sr-Nd-Hf-Pb isotopic ratios cannot be used to identify this crustal input because Groups 1 and 2 are identical in these isotope systems. Interaction with a mafic underplate from older Cenozoic or accreted Mesozoic arcs is likely, and Re-Os analyses of basement samples (in progress) will provide a test of this hypothesis. This study reveals that most primitive magmas in the Cascades have suffered variable crustal contamination, but only the Re-Os isotope system has the potential to delineate the extent of this involvement.

  9. Re Os isotopes applied to the epithermal gold deposits near Bucaramanga, northeastern Colombia

    Science.gov (United States)

    Mathur, R.; Ruiz, J.; Herb, P.; Hahn, L.; Burgath, K.-P.

    2003-01-01

    The epithermal gold mineralization near Bucaramanga, Colombia, is spatially associated with a dacitic porphyry of Upper Cretaceous to Early Tertiary age. Two mining districts in the vicinity of Bucaramanga, the California and the Vetas, host different styles of mineralization that could be interpreted as high- and low-sulfidation style mineralization, respectively. Re-Os isotope systematics were used on sulfide-gold-rich gravity concentrates in an attempt to determine both the ages of the epithermal deposits and the possible genetic relationships between the porphyry and the epithermal mineralization. The concentration of Os for sulfide samples taken from both systems is relatively uniform, ranging from 19 to 35 ppt (parts per trillion), whereas the Re concentration varies significantly, with the California system averaging 10 ppb (parts per billion) and the Vetas system averaging 140 ppb. The samples from the high-sulfidation California deposit form an isochron with an age of 57±10 Ma (MSWD=0.8), which overlaps with the age of the dacitic volcanism. The initial 187Os/ 188Os of the isochron is 1.20±0.13 and indicates a predominately crustal source for the Os and, by inference, gold. The samples from the Vetas low-sulfidation system have very high Re/Os ratios and do not lie on the isochron. These data reveal a difference between two epithermal systems that border one intrusion. Sulfide samples from the high-sulfidation system are isotopically homogenous with respect to Re-Os (form an isochron) and probably represent mineralization linked closely with the high temperature volatiles/fluids from the magma. In contrast, the sulfides from the Vetas system are in disequilibrium with respect to Re-Os and may illustrate mineralization that is not directly related to similar magmatic fluids.

  10. Re-Os isotopic composition of the Dongling ⅢCD iron meteorite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Re,Os concentrations and Os isotopic compositions of the Dongling ⅢCD iron meteorite were determined by N-TIMS technique. The result was compared with that of the other irons and chondrites. The Re and Os concentrations of the Dongling iron meteorite were plotted on the trends of the group ⅢA and ⅣA irons. The Pt-Os relation of the Dongling iron meteorite is similar to that of the group ⅡA irons. That suggests a higher fractionation for the Dongling iron meteorite.

  11. Re-Os isotopic dating of chalcopyrite from the Abalieke copper-lead deposits in West Kunlun, China%西昆仑阿巴列克铜铅矿床黄铜矿Re-Os定年及地质意义

    Institute of Scientific and Technical Information of China (English)

    张正伟; 漆亮; 沈能平; 游富华; 张中山; 周灵洁

    2011-01-01

    It is a very important and effective method of analyzing the ore-forming processes by taking advantage of geochemistry analytical approaches as well as traditional ways, such as testing the Re-Os, discriminating the paragenetic association of the minerals and the tectonic settings. Seven chalcopyrite and one pyrite samples from the main orebody of Abalieke Cu-Pb deposit are used for Re-Os dating. The chalcopyrite is associated with galenite and dolomite which contain 626 x 10 " ~ 14533 x 10 ~ of Re and 0. 026 x 10 ~0. 36 x 10 "9 of Os respectively, and yield a Hercynina isochron age of 331. 3 ±5. 2Ma. High Re/Os ratio, low Os concentration and highly radiogenic Os isotopic ratios of these samples suggest that they are of crustal origin. The tectonic evolving shows that the southwestern margin of the Tarim block was a passive continental margin in the Late Paleozoic era. Because of the Paleo-Tethys ocean movement during Carboniferous, the depression basin are formed in margin of Tarim craton, comprised lead-zinc deposits in clastic rock-carbonate host stratum that cover up the Devonian. This Re-Os isotopic dating age of chalcopyrite is nearly closed with ore-hosted stratum. Our Re-Os result provides new evidences, showing that Abalieke Cu-Pb deposit experienced the syngenetic ore-forming process in Hercynina Also this study gives important geochemical evidence on such issues; the lead-zinc deposits are mainly sedimentary formation-controlled type; the ore-forming elements mainly came from stratum; mineralization occurred in the joint position between Upper Devonian and Lower Carboniferous, while the rock in which mainly consist of sandstone and carbonatite formation. It can be seen that the metallogenic system of the copper-lead-zinc strata-bound deposits in carbonate rock has a certain complexity and provides wider space for further researches.%除了传统的测试Rb-Sr、Sm-Nd、U-Th-Pb、K-Ar或Ar-Ar等方法来讨论碳酸盐岩层控型铅锌矿的成矿年

  12. Re-Os Dating of Galena and Sphalerite from Lead-Zinc Sulfide Deposits in Yunnan Province, SW China

    Institute of Scientific and Technical Information of China (English)

    Yingying Liu; Liang Qi; Jianfeng Gao; Lin Ye; Zhilong Huang; Jiaxi Zhou

    2015-01-01

    Dating of lead-zinc deposits is of critical importance for better understanding of ore ge-nesis, but has long been a big challenge due to the lack of suitable minerals that can be unequivocally linked to the ore genesis and that can be used for tradition radiometric methods. This kind of deposits have simple mineralogy dominated by galena and sphalerite commonly associated with calcite and oth-er gangue minerals. Both galena and sphalerite have low and high variable Re concentrations and thus Re-Os dating of these minerals have been less promising. In addition, the recovery of Re is extremely low for galena when conventional method was applied, lending additional difficulty in precisely dating galena. In this study, we investigate the recovery of Re using different media for anion exchange sepa-ration and reporte a revised preparation method for Re-Os dating of galena and sphalerite. By using the new protocol, two reliable Re-Os isochron ages of galena and sphalerite from the Fule (20.4±3.2 Ma) and Laochang (308±25 Ma) Pb-Zn deposits in Yunnan Province, SW China, are achieved.

  13. Re-Os and S isotope evidence for the origin of Platreef mineralization (Bushveld Complex)

    Science.gov (United States)

    Yudovskaya, M.; Belousova, E.; Kinnaird, J.; Dubinina, E.; Grobler, D. F.; Pearson, N.

    2017-10-01

    The Bushveld Complex contains the largest platinum-group element (PGE) deposits of the world that are represented by persistent stratiform reefs highly enriched with PGE with respect to underlying and overlying rocks. New Re-Os isotope and elemental LA MC-ICPMS data on platinum-group minerals (PGM) from the mineralized reefs are presented with implications to correlation between the different segments of the Bushveld Complex and a role of superimposed processes at the reef formation. We analyzed laurite (RuS2), hollingworthite (RhAsS), sperrylite (PtAs2) and Pt-Fe alloys from the Merensky Reef, Pseudoreef and the PGE reef of the Platreef. The measured 187Os/188Os value for Platreef laurite is 0.1751 ± 0.0004 whereas the ratios for sperrylite and hollingworthite range to slightly higher values (0.1713-0.1818 and 0.1744-0.1835 respectively). The observed textures of the analyzed PGM, such as Pt-Fe symplectites in base metal sulfides (BMS), laurite inclusions in chromite and sperrylite rims around sulfide-silicate aggregates, are interpreted as features of primary magmatic crystallization whereas hollingworthite overgrowths and exsolutions in sperrylite are likely to have originated from later solid state transformation or metasomatic processes. The Platreef is a composite sill-like body in the northern limb correlative to the Critical Zone in terms of stratigraphic position, whole-rock geochemistry and isotope characteristics. The pristine magmatic character of sulfides and PGM in the stratiform reefs at the top of the Platreef strongly resembles the style of Merensky Reef mineralization. However, the basal part of the Platreef pyroxenitic sequence is variably contaminated and mineralized with a significant hydrothermal overprint. Sulfides from underlying Lower Zone peridotite yield δ34S values varying from +9‰ to +14.2‰ that are much higher than the values for the overlying Platreef and are a consequence of sulfur assimilation from sedimentary sulfates. The

  14. 内蒙古兴和县曹四夭特大型钼矿床辉钼矿Re-Os同位素年龄及地质意义%Re-Os Isotopic Age Dating of the Molybdenite Separated from the Caosiyao Giant Molybdenum Deposit, Xinghe County, Inner Mongolia, and Its Geological Significances

    Institute of Scientific and Technical Information of China (English)

    聂凤军; 李香资; 李超; 赵宇安; 刘翼飞

    2013-01-01

    porphyry stocks as veins, veinlets and disseminated blocks. The molybdenum ore consists of pyrite, molybdenite, chalcopyrite, sphalerite, wolframite, K-feldspar, quartz, sericite, chlorite and epidote. As the most important economic molybdenum mineral, molybdenite occurs as impregnation, radioflake, thin film, aggregated flakes and veinlet. Re-Os isotopic age dating on four molybdenite samples from the main orebody gives model ages of 131. 9 ± 2. 3Ma, 131. 2±2. 3Ma, 129. 7 ± 2. OMa and 128. 6 ± 2. 4Ma, with an average value of 130. 4 ±2. 4Ma, which is similar to that of zircon U-Pb age of the ore-bearing granitoid porphyry. As the Re-Os model ages are in agreement with field geological evidences, and the molybdenite has co-existing relations with pyrite and chalcopyrite, it has been suggested that the Re-Os model ages represent the ore-forming time of the Mo mineralization occurring in the Caosiyao district and its neighboring area. Preliminary studies show that the Caosiyao deposit were formed during the Mesozoic Yanshanian extensional tectonic movements that resulted in the intensive igneous activities. It is believed to be a product of the Early Cretaceous intraplate granitoid magmatism within the Liangcheng uplift. The well-developed high K and SiO2 granitoid porphyry stocks and dykes might have acted as the "engines" of the ore-forming systems. Most of the Mo was derived from partial melting of the Precambrian continental crust. The ore-forming fluid was dominated by magmatic water at the early metallogenic stage, and was characterized by mixture with magmatic water as the major source at the main metallogenic stage. The combined geochemical data, field geological observations and petrological evidence indicate that the Caosiyao deposit belongs to the porphyry type Mo deposit. The genetic model and mineral exploration criteria of the Caosiyao deposit can also be used as useful tools during the comprehensive evaluation of concealed Mo deposits in Inner Mongolian

  15. Re-Os dating of Mo-bearing black shale of the Laoyaling deposit, Tongling, Anhui Province, China

    Institute of Scientific and Technical Information of China (English)

    YANG Gang; CHEN Jiangfeng; DU Andao; QU Wenjun; YU Gang

    2004-01-01

    Laoyaling is a typical stratiform deposit in the Tongling district and the molybdenum orebody is hosted by black shale of the Dalong Formation of the Upper Permian system. Eight black shale samples from the Laoyaling Mo orebody were dated by Re-Os technique using ICP-MS,which give an isochron age of 234.2±7.3 Ma with an initial 187Os/188Os ratio of 1.37±0.39. The apparent Re-Os age is a few million years younger than the depositional age of the Late Permian. The young isochron age may be caused by the later hydrothermal disturbance or mass fractionation during ICP-MS measurement. However, the obtained isochron age is close to the depositional age and far earlier than those of the Late Yanshanian intrusions. It suggests that the Mo ore of the Laoyaling deposit is sedimentary in origin and not related to the Late Yanshanian magmatism. Black shales of the Upper Permian are distributed widely in the Mid-Lower Yangtze region, our result is important for understanding the ore-forming processes in the region and broadens the exploration target.

  16. Re-Os (ICP-MS) dating of the massive sulfide ores from the Jinchuan Ni-Cu-PGE deposit

    Institute of Scientific and Technical Information of China (English)

    YANG Gang; DU Andao; LU Jiren; QU Wenjun; CHEN Jiangfeng

    2005-01-01

    Massive sulfide ore from the Jinchuan Ni-Cu-PGE deposit was dated by Re-Os technique using Carius Tube digestion, Os distillation, Re extraction by acetone and ICP-MS measurement. An isochron giving an age of 833 ± 35 Ma, initial 187Os/188Os ratio of 0.279 ± 0.018 (MSWD = 1.7) and γOs = 130 ± 15 is obtained. The Re-Os age obtained agrees, within analytical uncertainties, with previous SHRIMP zircon U-Pb age of 827 ± 8 Ma (n=5, MSWD = 4.3). The result suggests that the deposit was formed at Neoproterozoic and that the formation of the Jinchuan Ni-Cu-PGE sulfide deposit may be closely related to the plume activity, which were attributed to the breakup of the Rodinia supercontinent. The high γOs of the massive ores suggests that crustal material was involved in the formation of the Jinchuan deposit, however, the quantity of the added crustal material is less than 10%.

  17. Re-Os isotope measurements of single sulfide inclusions in a Siberian diamond and its nitrogen aggregation systematics

    Science.gov (United States)

    Pearson, D. G.; Shirey, S. B.; Bulanova, G. P.; Carlson, R. W.; Milledge, H. J.

    1999-03-01

    We have measured the Re-Os isotopic compositions of individual syngenetic sulfide inclusions from three different growth zones within a central cross section plate cut from a single Siberian diamond. Individual sulfides in their diamond host were isolated by laser cutting. The sulfides, and hence the different growth zones of the diamond have been suggested to differ in age by up to 2 Ga on the basis of their Pb isotope compositions. Re-Os model ages of the four inclusions range from 3.1 ± 0.3 to 3.5 ± 0.3 Ga and suggest a Middle Archaean age for the diamond. A sulfide inclusion in the rim of the diamond is very different in elemental composition from those of the core and intermediate zones. It is enriched in Os, Re, Pb, and Zn and has more radiogenic Os and Pb isotopes. The inclusion is connected to the surface of the diamond by a healed crack, revealed by cathodoluminescence. The compositional distinction may be caused either by postformational interaction between an ancient sulfide and a fluid, possibly at the time of kimberlite eruption, or later stage growth of new diamond plus sulfide. Such chemical complexities, and the presence of healed fractures within the host diamond, emphasize the desirability of analyzing individual inclusions from well-characterized diamonds if isotope data for inclusions are to be better understood. Nitrogen contents and aggregation state in the core and intermediate zone of the host diamond closely approximate theoretically calculated isotherms based on consideration of experimentally determined nitrogen aggregation kinetics. The nitrogen content of the rim diamond is too low to obtain spectra that allow accurate deconvolution of relative aggregation levels for use in residence time calculations. The aggregation state of nitrogen in the core and intermediate growth zones is compatible with a long, ca. 3 Ga mantle residence time at normal lithospheric temperatures. The similarity of the sulfide inclusion Re-Os model ages to the

  18. Re-Os isotopic age dating of molybdenite separates from Hashitu Mo deposit in Linxi County of Inner Mongolia and its geological significance%内蒙古林西县哈什吐钼矿床辉钼矿铼-锇年龄及其地质意义

    Institute of Scientific and Technical Information of China (English)

    张可; 聂凤军; 侯万荣; 李超; 刘勇

    2012-01-01

    Located in the eastern part of the southern Da Hinggan Ling Late Paleozoic orogenic belt between the Silas Wood Aaron River and the Erlian-Hegenshan structure zone, the newly discovered Hashitu ore deposit is a medium-size porphyry molybdeoum deposit occurring in east-central Inner Mongolian. The Hashitu granite porphyry and biotite granite were emplaced in the widespread Quaternary sedimentary sequence in the Hashitu mineralized area. The granite porphyry intruded into the biotite granite in a slightly later period, and the two granite intrusions made up a Yanshanian complex. The Mo mineralization occurred entirely in the two types of Mesozoic granitic intrusive rocks in stratiform, lenticular and chambered forms at large steep angles. The metallic minerals of the ores from Hashitu are mainly molybdenite and subordinate, pyrite, chalcopyrite, pyrrhotite, arsenopyrite and galena, whereas the gangue mineral assemblage consists of mainly quartz, sericite and subordinately chlorite, epidote, fluorite and feldspar. Re-Os isotopic age dating of ten molybdenite separates from No. 1 Mo ore body yielded an isochron age of (148.8 ± 1.6) Ma and model ages ranging from (147.0 ± 2.2) Ma to (149.5 ± 2.3) Ma with an average of (148.22 ± 0.67) Ma. As the age is in agreement with field geological evidence, the authors hold that the molybdenum was concentrated from the Mo-bearing hydrothermal fluid after the intrusion of the granite porphyry and biotite granite during the Late Jurassic period. The Re content of molybdenite is (652~2 055) × 10-9, averaging 1 284 × 10-9. The content of Re in the Hashitu Mo deposit in comparison with the Re values of other molybdenum-bearing deposits indicates that the ore-forming materials of the Hashitu Mo deposit might have been derived mainly from the crustal source.%内蒙古哈什吐矿床是新发现的钼矿床.为进一步查明哈什吐钼矿床的形成时间,首次对主要钼矿体的10件辉钼矿样品进行铼-锇同位素分

  19. New Re-Os Isotopic Constrains on the Formation of the Metalliferous Deposits of the Lower Cambrian Niutitang Formation

    Institute of Scientific and Technical Information of China (English)

    Yong Fu; Lin Dong; Chao Li; Wenjun Qu; Haoxiang Pei; Wenlang Qiao; Bing Shen

    2016-01-01

    ABSTRACT:The Terreneuvian Epoch (541–521 Ma)is also an important period for metallogenesis in South China, as was represented by the widespread occurrences of Ni-Mo polymetallic layers on the antecedent shallow platform margin and the V-enriched black shales in deeper slope-basin settings. In this study, we have measured Re-Os isochron ages of Ni-Mo polymetallic layers (Songlin, Niuchang, Sancha, Chuanpengwan), V-rich black shales (Bahuang), and non-metalliferous black shales (Shuidong) in the basal Niutitang Formation in Guizhou and Hunan province, South China. The Ni-Mo polymetal-lic layers and V-enriched black shales have similar Re-Os isochron ages, suggesting concurrent deposi-tion of these two types of metalliferous ores. This suggestion is consistent with the traditional strati-graphic correlation by using the nodular phosphorite bed directly underlying these metalliferous layers as a stratigraphic marker. Furthermore, the metalliferous ores and non-metalliferous black shales have similar initial 187Os/188Os ratios of 0.8–0.9, arguing for a dominant seawater origin with minor contri-bution of hydrothermal activity. Furthermore, Re-Os isotopic data also imply that Ni-Mo and V ore might have derived from the same source. We suggest that the spatial distribution of metalliferous ores can be explained by the development of non-sulfidic anoxic-suboxic wedge (NSASW) in the slope-basin and sulfidic wedge in the previous platform margin. Upwelling of deep water first transects the mildly reduced, organic rich NSASW, in which V (V) is reduced to V (IV), and is preferentially removed from seawater by organometallic complex formation. As a result, V-rich black shale deposits in the slope-basin of Yangtze Platform. Further movement of deep water into the sulfidic platform margin results in Ni-Mo polymetallic layer formation.

  20. Re-Os Dating of the Pulang Porphyry Copper Deposit in Zhongdian, NW Yunnan, and Its Geological Significance

    Institute of Scientific and Technical Information of China (English)

    ZENG Pusheng; HOU Zengqian; WANG Haiping; QU Wenjun; MENG Yifeng; YANG Zhusen; LI Wenchang

    2004-01-01

    The Pulang porphyry copper deposit is located in the Zhongdian island arc belt, NW Yunnan, in the central part of the Sanjiang area, SW China, belonging to the southern segment of the Yidun island arc belt on the western margin of the Yangtze Platform. In the Yidun island arc, there occur well-known "Gacun-style" massive sulfide deposits in the northern segment and plenty of porphyry copper deposits in the southern segment, of which the Pulang porphyry copper deposit is one of the representatives. Like the Yulong porphyry copper deposit, this porphyry copper deposit is also one of the most important porphyry copper deposits in the eastern Qinghai-Tibet Plateau. But it is different from other porphyry copper deposits in the eastern Qinghai-Tibet Plateau (e.g. those in the Gangdise porphyry copper belt and Yulong porphyry copper belt) in that it formed in the Indosinian period, while others in the Himalayan period. Because of its particularity among the porphyry copper deposits of China, this porphyry copper deposit is of great significance for the study of the basic geology and the evaluation and prediction of mineral resources in the Zhongdian island arc belt.However, no accurate chronological data are available for determining the timing of mineralization of the porphyry copper deposit. By field observation in the study area and Re-Os dating of molybdenite and K-Ar dating of hydrothermal minerals and whole rock from the typical geological bodies, the timing of mineralization of the porphyry copper deposit has systematically been determined for the first time. The K-Ar age for the hydrothermal mineralization of biotite-quartz monzonitic porphyry that has undergone patassic silicate (biotite and K-feldspar) alteration ranges from 235.4±2.4 to 221.5±2.0 Ma and the Re-Os age for molybdenite in the quartz-molybdenite stage is ~213±3.8 Ma. These data are very close to each other, suggesting that the ore-forming processes of the Pulang porphyry copper deposit was

  1. Re-Os Isotopic Dating of Molybdenite of Pingdi Molybdenum Deposits in Wuyishan,Fujian Province and Its Geological Significance%福建武夷山坪地钼矿辉钼矿铼-锇同位素定年及其地质意义

    Institute of Scientific and Technical Information of China (English)

    王翠芝; 李超

    2012-01-01

    this molybdenum deposit. We collected molybdenites with different occurrences and elevations from different ore bodies of Pingdi molybnum deposits for Re-Os isotopic dating. The isochron age of (102.9 ±1.8) Ma(MSWD =2.1) , and the model age of (107.4 ±3. 3) Ma ( MSWD = 16) were obtained. This results indicated the multi-stages mineralization with three types of molybdenite such as fine veins in rock of K-feldspar granite, thick veins in "bedding joint" of K-feldspar granite and in breccia silicified rocks controlled by fractures, which were formed in different metallogenic phases ,(111.20 ±1.7) Ma-(111. 60 ±1.6) Ma, (105.60 ±1.6) Ma - (107.40 ± 1. 6) Ma and (103.70±1.7) Ma, the mineralization periods during late stage of early cretaceous. This isotopic data provided the new geochemical evidences for Mesozoic tectonic magma evolution and guided regional ore-exploration of Pucheng-Ningde NW tectonic belt of Southeast coast of Fujian Province.

  2. Re-Os isotopic systematics of primitive lavas from the Lassen region of the Cascade arc, California

    Science.gov (United States)

    Borg, L.E.; Brandon, A.D.; Clynne, M.A.; Walker, R.J.

    2000-01-01

    Rhenium-osmium isotopic systematics of primitive calc-alkaline lavas from the Lassen region appear to be controlled by mantle wedge processes. Lavas with a large proportion of slab component have relatively low Re and Os abundances, and have radiogenic Os and mid ocean ridge basalt-like Sr and Pb isotopic compositions. Lavas with a small proportion of slab component have higher Re and Os elemental abundances and display mantle-like Os, Sr, Nd, and Pb isotopic compositions. Assimilation with fractional crystallization can only generate the Re-Os systematics of the Lassen lavas from a common parent if the distribution coefficient for Re in sulfide is ~40-1100 times higher than most published estimates and if most incompatible element abundances decrease during differentiation. High Re/Os ratios in mid ocean ridge basalts makes subducted oceanic crust a potential source of radiogenic Os in volcanic arcs. The slab beneath the southernmost Cascades is estimated to have 187Os/188Os ratios as high as 1.4. Mixing between a slab component and mantle wedge peridotite can generate the Os isotopic systematics of the Lassen lavas provided the slab component has a Sr/Os ratio of ~7.5X105 and Os abundances that are 100-600 times higher than mid ocean ridge basalts. For this model to be correct, Os must be readily mobilized and concentrated in the slab component, perhaps as a result of high water and HCl fugacities in this subduction environment. Another possible mechanism to account for the correlation between the magnitude of the subduction geochemical signature and Os isotopic composition involves increasing the stability of an Os-bearing phase in mantle wedge peridotites as a result of fluxing with the slab component. Melting of such a source could yield low Os magmas that are more susceptible to crustal contamination, and hence have more radiogenic Os isotopic compositions, than magmas derived from sources with a smaller contribution from the slab. Thus, the addition of the

  3. The Re-Os Isotopic System: Geochemistry and Methodology at the Geochronological Research Center (CPGeo of the University of São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Ciro Teixeira Correia

    2007-04-01

    Full Text Available The Re-Os isotopic system is an important tool for the study of mantle-crust processes, geochronology and the tracingof source reservoirs for metal deposition. Rhenium and osmium differ fundamentally from other lithophile isotopic systemswith regards to their behavior during partial melting processes, coupled with the chalcophile/siderophile nature of bothelements. These differences make the system extremely useful for a number of novel applications not traditionally addressedby lithophile isotopic systems. A low-blank technique for the analysis of Re-Os isotopes in geological materials has beenestablished at the Geochronological Research Center (CPGeo of the Geosciences Institute of the University of São Paulo,Brazil, with the aim of furthering knowledge of regional geology, tectonic evolution, petrology and ore deposition in SouthAmerica. The techniques described here use isotope dilution to simultaneously determine the concentration of Os and Re aswell the Os isotopic composition of geologic materials. Sample digestion and sample-isotopic spike equilibration are achievedin sealed borosilicate glass tubes at high temperature. Osmium is separated and purified by carbon tetrachloride solventextraction and micro-distillation techniques. Rhenium is separated and purified by anion exchange chromatography. Accuracyof the concentration and isotopic determinations is monitored by the analysis of a certified reference material (WPR-1 andthe use of the Department of Terrestrial Magnetism (DTM Os isotopic standard. Measured values and precision of thesestandards is within error and comparable to established Re-Os laboratories.

  4. In situ Re-Os isotope ages of sulfides in Hannuoba peridotitic xenoliths: Significance for the frequently-occurring mantle events beneath the North China Block

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In situ Re-Os isotopes of sulfides in peridotitic xenoliths from Cenozoic Hannuoba basalts were analyzed by LAM-MC-ICPMS. The suifides developed two types of occurrences including silicate-enclosed and interstitial. In the enclosed sulfides, 187Os/188Os vary from 0.1124 to 0.1362 and 187Re/188Os from 0.0026 to 1.8027. In the interstitial ones, 187Os/188Os have a range from 0.1174 to 0.1354 and 187Re/188Os from 0.0365 to 1.4469. The oldest age, calculated by TRD for the enclosed sulfides, is 2.1 Ga. An isochron age of 2.3±1.2 Ga is obtained by five grains of enclosed sulfides and primitive mantle. The sulfides used have lower Re-Os isotopic ratio than primitive mantle. Meanwhile, an isochron age of 645±225 Ma is given by all interstitial sulfides and the enclosed sulfides with higher Re-Os isotopic ratio due to Re addition after mantle formation. In addition, the model age of 1.3 Ga recorded by one interstitial sulfide, having similar TDM and TRD, should be meaningful to deep thermal event. The coexistence of different ages, revealed by in situ Re-Os isotope, indicates frequently-occurring mantle events beneath Hannuoba area.

  5. Re - Os isotopic constraints on the origin of volcanic rocks, Gorgona Island, Colombia: Os isotopic evidence for ancient heterogeneities in the mantle

    Science.gov (United States)

    Walker, R.J.; Echeverria, L.M.; Shirey, S.B.; Horan, M.F.

    1991-01-01

    The Re - Os isotopic systematics of komatiites and spatially associated basalts from Gorgona Island, Colombia, indicate that they were produced at 155??43 Ma. Subsequent episodes of volcanism produced basalts at 88.1??3.8 Ma and picritic and basaltic lavas at ca. 58 Ma. The age for the ultramafic rocks is important because it coincides with the late-Jurassic, early-Cretaceous disassembly of Pangea, when the North- and South-American plates began to pull apart. Deep-seated mantle upwelling possibly precipitated the break-up of these continental plates and caused a tear in the subducting slab west of Gorgona, providing a rare, late-Phanerozoic conduit for the komatiitic melts. Mantle sources for the komatiites were heterogeneous with respect to Os and Pb isotopic compositions, but had homogeneous Nd isotopic compositions (??Nd+9??1). Initial 187Os/186Os normalized to carbonaceous chondrites at 155 Ma (??Os) ranged from 0 to +22, and model-initial ?? values ranged from 8.17 to 8.39. The excess radiogenic Os, compared with an assumed bulk-mantle evolution similar to carbonaceous chondrites, was likely produced in portions of the mantle with long-term elevated Re concentrations. The Os, Pb and Nd isotopic compositions, together with major-element constraints, suggest that the sources of the komatiites were enriched more than 1 Ga ago by low (<20%) and variable amounts of a basalt or komatiite component. This component was added as either subducted oceanic crust or melt derived from greater depths in the mantle. These results suggest that the Re - Os isotope system may be a highly sensitive indicator of the presence of ancient subducted oceanic crust in mantle-source regions. ?? 1991 Springer-Verlag.

  6. Re-Os isotope evidence from Mesozoic and Cenozoic basalts for secular evolution of the mantle beneath the North China Craton

    Science.gov (United States)

    Huang, Feng; Xu, Ji-Feng; Liu, Yong-Sheng; Li, Jie; Chen, Jian-Lin; Li, Xi-Yao

    2017-05-01

    The mechanism and process of lithospheric thinning beneath the North China Craton (NCC) are still debated. A key criterion in distinguishing among the proposed mechanisms is whether associated continental basalts were derived from the thinning lithospheric mantle or upwelling asthenosphere. Herein, we investigate the possible mechanisms of lithospheric thinning based on a systematic Re-Os isotopic study of Mesozoic to Cenozoic basalts from the NCC. Our whole-rock Re-Os isotopic results indicate that the Mesozoic basalts generally have high Re and Os concentrations that vary widely from 97.2 to 839.4 ppt and 74.4 to 519.6 ppt, respectively. They have high initial 187Os/188Os ratios ranging from 0.1513 to 0.3805, with corresponding variable γOs(t) values (+20 to +202). In contrast, the Re-Os concentrations and radiogenic Os isotope compositions of the Cenozoic basalts are typically lower than those of the Mesozoic basalts. The lowest initial 187Os/188Os ratios of the Cenozoic basalts are 0.1465 and 0.1479, with corresponding γOs(t) values of +15 and +16, which are within the range of ocean island basalts. These new Re-Os isotopic results, combined with the findings of previous studies, indicate that the Mesozoic basalts were a hybrid product of the melting of pyroxenite and peridotite in ancient lithospheric mantle beneath the NCC. The Cenozoic basalts were derived mainly from upwelling asthenosphere mixed with small amounts of lithospheric materials. The marked differences in geochemistry between the Mesozoic and Cenozoic basalts suggest a greatly reduced involvement of lithospheric mantle as the magma source from the Mesozoic to the Cenozoic. The subsequent lithospheric thinning of the NCC and replacement by upwelling asthenospheric mantle resulted in a change to asthenosphere-derived Cenozoic basalts.

  7. APPLICATIONS OF THE Re-Os ISOTOPE SYSTEM TO METEORITES%Re-Os同位素体系在陨石研究中的应用

    Institute of Scientific and Technical Information of China (English)

    杨刚; 谢智; 陈江峰

    2001-01-01

    铁陨石中的Re,Os含量反映其结晶分异历史。通过铁陨石定年修正187Re的衰变常数为:λ(187Re)=1.666×10-11a-1。Re Os同位素测年法可以直接用于对铁陨石的定年,结果表明天然铁陨石大体同时形成,但Re Os定年技术已有可能揭示不同化学群铁陨石形成年代的序列,但研究尚需深入。这些方法也可以用来探讨铁陨石和石铁陨石的形成源区、冷却历史和后期变化。虽然在石陨石中Re,Os同位素的浓度很低,但也有了探索性研究成果。随着技术的不断发展,Re Os同位素体系在天体化学中的作用将愈加明显和重要。%The concentrations of Re and Os in iron meteorites could indicate the history of differentiation and crystallization of irons. The decay constant of 187Re has been corrected by studying iron meteorites and the new decay constant λ(187Re)=1.666×10-11a-1. Re-Os chronology could be directly used to date iron meteorites. The results from the method show that all iron meteorites were formed at about the same time. However, further study suggests that different groups of irons were crystallized at slightly different times. This method also helps in studying the source, cooling history and secondary alterations of the chondrites and iron meteorites. Although the Re and Os concentrations are very low in the ordinary chondrites, some results have been obtained in this field. As a powerful cosmochemical tracer, the Re-Os isotopic system will help much in a better understanding of origin and evolution of meteorites.

  8. Re-Os isotope systematics in black shales from the Lesser Himalaya: their chronology and role in the 187Os/ 188Os evolution of seawater

    Science.gov (United States)

    Singh, Sunil K.; Trivedi, J. R.; Krishnaswami, S.

    1999-08-01

    Re and Os abundances and Os isotope systematics have been measured in a number of black shales sampled from outcrops and two underground phosphorite mines, Maldeota and Durmala, in the Lesser Himalaya. The Re and Os concentrations in these samples exhibit wide range, 0.2 to 264 ng/g and 0.02 to 13.5 ng/g, respectively, with a mean Re/Os of ˜25. The 187Os/ 188Os of these samples also show a broad range 1.02 to 11.6, with many of them far more radiogenic than the currently eroding continental crust. The black shales from the Maldeota and Durmala mines, collected a few meters above the Krol-Tal (Pc-C) boundary and occurring in the same stratigraphic horizon, yield 187Re- 187Os isochron ages of 554 ± 16 and 552 ± 22 Ma, respectively, consistent with fossil evidences and those assigned for the Pc-C boundary at various other locations. These results indicate closed system behaviour of Re and Os in these mine samples and reaffirm the validity of 187Re- 187Os pair to date organic-rich sediments. The age of these mine samples from the outer belt seems to be a few hundred millions of years younger than the preliminary Re-Os age of 839 ± 138 Ma for black shales from Theog, collected from the inner belt. These initial results lean toward the hypothesis that the inner belt sediments were deposited earlier than the outer belt; however, more analyses of black shales are needed to confirm this. The role of weathering black shales from the Himalaya in contributing to the Os isotope evolution of seawater over the past ˜25 Ma was assessed using a simple budget model for seawater Os and assuming values for Os fluxes and 187Os/ 188Os based on the available limited data on Os concentration and its 187Os/ 188Os in rivers and oceans. These calculations indicate that the required contributions from black shale weathering to account for the entire increase in oceanic 187Os/ 188Os over the past ˜16 Ma is difficult to satisfy by varying only the Os flux from HTP rivers ( 187Os/ 188Os

  9. U-Pb, Re-Os and Ar-Ar dating of the Linghou polymetallic deposit, Southeastern China: Implications for metallogenesis of the Qingzhou-Hangzhou metallogenic belt

    Science.gov (United States)

    Tang, Yanwen; Xie, Yuling; Liu, Liang; Lan, Tingguan; Yang, Jianling; Sebastien, Meffre; Yin, Rongchao; Liang, Songsong; Zhou, Limin

    2017-04-01

    The Qingzhou-Hangzhou metallogenic belt (QHMB) in Southeastern China has gained increasingly attention in recent years. However, due to the lack of reliable ages on intrusions and associated deposits in this belt, the tectonic setting and metallogenesis of the QHMB have not been well understood. The Linghou polymetallic deposit in northwestern Zhejiang Province is one of the typical deposits of the QHMB. According to the field relationships, this deposit consists of the early Cu-Au-Ag and the late Pb-Zn-Cu mineralization stages. Molybdenite samples with a mineral assemblage of molybdenite-chalcopyrite-pyrite ± quartz are collected from the copper mining tunnel near the Cu-Au-Ag ore bodies. Six molybdenite samples give the Re-Os model ages varying from 160.3 to 164.1 Ma and yield a mean age of 162.2 ± 1.4 Ma for the Cu-Au-Ag mineralization. Hydrothermal muscovite gives a well-defined Ar-Ar isochron age of 160.2 ± 1.1 Ma for the Pb-Zn-Cu mineralization. Three phases of granodioritic porphyry have been distinguished in this deposit, and LA-ICP-MS zircon U-Pb dating shows that they have formed at 158.8 ± 2.4 Ma, 158.3 ± 1.9 Ma and 160.6 ± 2.1 Ma, comparable to the obtained ages of the Cu-Au-Ag and Pb-Zn-Cu mineralization. Therefore, these intrusive rocks have a close temporal and spatial relationship with the Cu-Au-Ag and Pb-Zn-Cu ore bodies. The presences of skarn minerals (e.g., garnet) and vein-type ores, together with the previous fluid inclusion and H-O-C-S-Pb isotopic data, clearly indicate that the Cu-Au-Ag and Pb-Zn-Cu mineralization are genetically related to these granodiorite porphyries. This conclusion excludes the possibility that this deposit is of ;SEDEX; type and formed in a sag basin of continental rifts setting as previously proposed. Instead, it is proposed that the Linghou polymetallic and other similar deposits in the QHMB, such as the 150-160 Ma Yongping porphyry-skarn Cu-Mo, Dongxiang porphyry? Cu, Shuikoushan/Kangjiawang skarn Pb

  10. PGE geochemistry and Re Os dating of massive sulfide ores from the Baimazhai Cu Ni deposit, Yunnan province, China

    Science.gov (United States)

    Sun, Xiaoming; Wang, Shengwei; Sun, Weidong; Shi, Guiyong; Sun, Yali; Xiong, Dexin; Qu, Wenjun; Du, Andao

    2008-09-01

    The Baimazhai deposit in Yunnan Province is one of the largest Cu-Ni sulfide deposits hosted in mafic-ultramafic intrusions in China. Concentrations of platinum-group elements (PGE) in massive sulfide ores and host rocks from Baimazhai were determined by using inductively coupled plasma mass spectrometry (ICP-MS) following nickel sulfide fire assay pre-concentration. The results show that the total PGE (ΣPGE) are quite low, decreasing gradually from central massive ores (78.2-556 ppb) to olivine pyroxenite (0.472-67.0 ppb), gabbro (0.847 ppb) and, websterite (0.76-0.809). The intruded lamprophyre dykes also show low ΣPGE (2.98-4.07 ppb). The ΣPGE exhibit obvious positive correlations with Au, Ni and Cu contents. Primitive mantle normalized PGE patterns of the massive Cu-Ni ores are of the Pt-Pd type with relatively steep and trough-like patterns, which are similar to those of the host rocks. In addition, the Pt/Pd and Cu/Pd ratios of the massive sulfide ores are similar to those of olivine pyroxenite, gabbro and websterite. These characteristics suggest that sulfides in the massive ores are of magmatic origin, co-genetic with their host rocks. The relatively high Pt/Pd ratios of the Baimazhai massive sulfide ores (averaging 0.83) and their host rocks imply that the Baimazhai sulfides formed in a single sulfide saturation event, but not through multiple sulfide injections. High Ir contents (0.77-5.52 ppb, averaging 2.35 ppb) and dramatically variable Pd/Ir ratios (4.76-296, averaging 138) of the massive sulfide ores suggest that the Baimazhai sulfide ores might have suffered significant late stage hydrothermal alteration. The Baimazhai massive sulfide ores yield a Re-Os isochron age of 259 ± 20 Ma (MSWD = 0.025), which is the same as the major eruption stage of the Emeishan large igneous province and the Baimazhai intrusion, further supporting their magmatic origin. The initial 187Os/ 188Os value of 0.456 ± 0.026 indicates that crustal contamination has played

  11. PGE, Re-Os, and Mo isotope systematics in Archean and early Proterozoic sedimentary systems as proxies for redox conditions of the early Earth

    Science.gov (United States)

    Siebert, C.; Kramers, J. D.; Meisel, Th.; Morel, Ph.; Nägler, Th. F.

    2005-04-01

    Re-Os data and PGE concentrations as well as Mo concentrations and isotope data are reported for suites of fine clastic sediments and black shales from the Barberton Greenstone Belt, South Africa (Fig Tree and Moodies Groups, 3.25-3.15 Ga), the Belingwe Greenstone Belt, Zimbabwe (Manjeri Formation, ca. 2.7 Ga) and shales from the Witwatersrand, Ventersdorp and Transvaal Supergroups, South Africa ranging from 2.95 to 2.2 Ga. Moderately oxidizing conditions are required to mobilize Re and Mo in the environment, Mo fractionation only occurs in solution, and these parameters thus have potential use as paleoredox proxies for the early Earth. PGE + Re abundance patterns of Barberton Greenstone Belt sediments are uniform and very similar in shape to those of komatiites. This indicates (1) that the PGE came from a source of predominantly ultramafic composition and, (2) that PGE were transported and deposited essentially in particulate form. Sediments from the younger Belingwe Greenstone Belt show more fractionated PGE + Re patterns and have Re/Os ratios 10 to 100× higher than those of Barberton sediments. Their PGE abundance patterns and Re/Os ratios are intermediate between those of the mid-Archean shales and Neoproterozoic to Recent black shales. They reflect scavenging of Re from solution in the sedimentary environment. δ 98/95Mo values of black shales of all ages correlate with their concentrations. The Barberton Greenstone Belt samples have ˜1-3 ppm Mo, similar to a granitoid-basaltic source. This Mo has δ 98/95Mo between -1.9 and -2.4‰ relative to present day mean ocean water molybdenum, MOMO and is thus not isotopically fractionated relative to such a source. Similar to the PGE this indicates transport in solid form. Sediments from the Belingwe Greenstone Belt show in part enhanced Mo concentrations (up to 6 ppm) and Mo isotope fractionation (δ 98/95Mo up to -1.4‰ relative to MOMO). The combined PGE + Re and Mo data show mainly reducing conditions in the

  12. Re-Os isotopic data for molybdenum from Hejiangkou tungsten and tin polymetallic deposit in Chenzhou and its geological significance

    Institute of Scientific and Technical Information of China (English)

    刘德波; 杨柳; 邓湘伟; 戴雪玲; 王雄军; CHONGkhaiyuen; 杜高峰; 魏和平

    2016-01-01

    Hejiangkou W−Sn-polymetallic deposit is a newly found deposit in Xitian ore field, one of the important and large scale W−Sn-polymetallic ore fields in the middle segment of Nanling metallogenic zone. Re−Os isotope dating was used on three molybdenite samples from Hejiangkou deposit to determine the ore forming period. The result is (224.9±2.6)Ma−(225±3.1)Ma and isochron age is (225.5±3.6)Ma. The field geological observations, geochronological data and optical petrography indicated that Hejiangkou deposit underwent multi-period of superimposed mineralization. It can be differentiated into three periods composed of six mineralization stages. The first period is the initial period for hydrothermal metasomatism and metal element enrichment during Indosinian Epoch. Further enrichment, strong brittle fracturing and hydrothermal metasomatism, remobilization and superimposition happened in the second period, during early Yanshanian. It is the major mineralization period of Hejiangkou deposit and can be subdivided into four mineralization stages, namely the skarn stage, oxide stage, high-temperature sulfide stage and low-temperature sulfide stage. And the third period is the mineralization period of a porphyry-skarn system related to the emplacement of the granite porphyry dyke. As minerogenic epoch of Hejiangkou deposit is similar with Hehuaping deposit, they show the possibility of Indosinian mineralization event in Nanling metallogenic zone. It can be an important perspective in any future mineral exploration in the same metallogenic zone.

  13. ReOs isotope systematics of NiCu sulfide ores, Sudbury Igneous Complex, Ontario: evidence for a major crustal component

    Science.gov (United States)

    Walker, R.J.; Morgan, J.W.; Naldrett, A.J.; Li, C.; Fassett, J.D.

    1991-01-01

    Sudbury Igneous Complex sublayer ores from the Levack West, Falconbridge and Strathcona mines were analyzed for their Re and Os concentrations and Os isotopic compositions. The ReOs isotope systematics of three ores from the different mines give isochron ages of 1840 ?? 60 Ma, 1770 ?? 60 Ma and 1780 ?? 110 Ma, suggesting that the ReOs system became closed at the time of, or soon after the 1850 ?? 1 Ma crystallization age of the complex. The Os isotopic compositions of different portions of the complex at the time of crystallization varied considerably, with initial 187Os 186Os1850 ranging from 4.64 at Levack West to 7.55 at Strathcona. These heterogeneities require that the Os, and probably also the other platinum-group elements contained in the ores, were derived from at least two sources. In addition, the high initial 187Os 186Os ratios indicate that the Os was derived predominantly from ancient crust. Previous studies have suggested that the complex either crystallized from a mixture of mantle-derived basaltic melt and ancient continental crust, or was derived exclusively from the fusion of ancient continental crust resulting from a meteorite impact. Results of modelling suggest that if a contemporaneous mantle-derived basaltic melt was involved in the origin of the SIC, it likely contributed < 50% of the Os to all three ores. The large percentage of ancient crust involved in the production of the ores is most consistent with an interpretation of substantial crustal fusion resulting from meteorite impact. ?? 1991.

  14. Re-Os and Lu-Hf isotopic constraints on the formation and age of mantle pyroxenites from the Bohemian Massif

    Science.gov (United States)

    Ackerman, Lukáš; Bizimis, Michael; Haluzová, Eva; Sláma, Jiří; Svojtka, Martin; Hirajima, Takao; Erban, Vojtěch

    2016-07-01

    We report on the Lu-Hf and Re-Os isotope systematics of a well-characterized suite of spinel and garnet pyroxenites from the Gföhl Unit of the Bohemian Massif (Czech Republic, Austria). Lu-Hf mineral isochrons of three pyroxenites yield undistinguishable values in the range of 336-338 Ma. Similarly, the slope of Re-Os regression for most samples yields an age of 327 ± 31 Ma. These values overlap previously reported Sm-Nd ages on pyroxenites, eclogites and associated peridotites from the Gföhl Unit, suggesting contemporaneous evolution of all these HT-HP rocks. The whole-rock Hf isotopic compositions are highly variable with initial εHf values ranging from - 6.4 to + 66. Most samples show a negative correlation between bulk rock Sm/Hf and εHf and, when taking into account other characteristics (e.g., high 87Sr/86Sr), this may be explained by the presence of recycled oceanic sediments in the source of the pyroxenite parental melts. A pyroxenite from Horní Kounice has decoupled Hf-Nd systematics with highly radiogenic initial εHf of + 66 for a given εNd of + 7.8. This decoupling is consistent with the presence of a melt derived from a depleted mantle component with high Lu/Hf. Finally, one sample from Bečváry plots close to the MORB field in Hf-Nd isotope space consistent with its previously proposed origin as metamorphosed oceanic gabbro. Some of the websterites and thin-layered pyroxenites have variable, but high Os concentrations paralleled by low initial γOs. This reflects the interaction of the parental pyroxenitic melts with a depleted peridotite wall rock. In turn, the radiogenic Os isotope compositions observed in most pyroxenite samples is best explained by mixing between unradiogenic Os derived from peridotites and a low-Os sedimentary precursor with highly radiogenic 187Os/188Os. Steep increase of 187Os/188Os at nearly uniform 187Re/188Os found in a few pyroxenites may be connected with the absence of primary sulfides, but the presence of minor

  15. Re-Os isotopes and PGE geochemistry of black shales and intercalated Ni-Mo polymetallic sulfide bed from the Lower Cambrian Niutitang Formation, South China

    Institute of Scientific and Technical Information of China (English)

    JIANG Shaoyong; YANG Jinghong; LING Hongfei; FENG Hongzhen; CHEN Yongquan; CHEN Jianhua

    2003-01-01

    The Lower Cambrian Niutitang Formation consists of a thick black shale sequence with a regionally distributed conformable Ni-Mo polymetallic sulfide horizon and a chert bed at its basal strata on theYangtze Platform, South China. In this paper, we discuss all available data on Re-Os isotopes and Platinum Group Element (PGE) distribution pattern of the Ni-Mo polymetallic sulfide ore and its host rocks (black shales, cherts, and phosphorites) from Guizhou and Hunan provinces. Our results show that the black shales and the Ni-Mo sulfide ore have a high initial 187Os/188Os ratio of 0.78~0.86, indicating that the Early Cambrian ocean across the Yangtze Platform had a highly radiogenic Os value. This ratio is slightly lower than but still similar to present-day seawater, possibly as a result of high continental weathering at that time. The Ni-Mo sulfide ore yields a Re-Os isochron of 537±10 Ma (MSWD=11.9), possibly representing the depositional age of the Niutitang Formation. The chondrite-normalized PGE pattern, Pt anomaly (Pt/Pt*), Pt/Pd, Ir/Pd, Au/Ir and Re/Mo ratios of the Ni-Mo sulfide ore and its host rocks from South China indicate a varying source contribution of the PGE and other metals for different rocks. It is suggested that the cherts and Ni-Mo sulfide ore may have a significant proportion of PGE and probably other metals deriving from submarine-hydrothermal fluids with a mantle signature.

  16. Re-Os isotopic and trace element compositions of pyrite and origin of the Cretaceous Jinchang porphyry Cu-Au deposit, Heilongjiang Province, NE China

    Science.gov (United States)

    Zhang, Peng; Huang, Xiao-Wen; Cui, Bin; Wang, Bo-Chao; Yin, Yi-Fan; Wang, Jing-Rui

    2016-11-01

    The Jinchang Cu-Au deposit in Northeast China contains more than 76 tons of Au and 4683 tons of Cu with average ore grades of 11.34 g/t Au and 1.44% Cu. The deposit is typical of porphyry types and consists of gold orebodies mainly hosted in a ∼113 Ma granitic porphyry and breccia pipes within the porphyry intrusion. Mineralization is closely associated with early potassic alteration and late phyllic alteration. Pyrite is the main Au-bearing mineral and contains 1.48-18.9 ppb Re and 11.4-38 ppt common Os. Extremely low common Os concentrations and high Re/Os ratios are indicative of derivation of ore-forming materials from the crust. Low Re in pyrite from the Jinchang deposit may indicate a mixing source of mantle and crust or a crustal source. Five Re-Os isotopic analyses yield a model 1 isochron age of 114 ± 22 Ma (2σ, MSWD = 0.15), similar to the age of the host porphyry. Pyrite contains detectable Co, Ni, Cu, Zn, As, Ag, Au, Sb, Pb and Bi. Pyrite has Co/Ni ratios similar to that of volcanogenic and hydrothermal sulfide deposits, indicating a magmatic-hydrothermal origin, and has Au and As contents similar to that of porphyry-epithermal systems. Pyrite grains from potassic and phyllic alteration stages have different trace element contents, reflecting the evolution of ore-forming fluids from magmatic dominated to magmatic mixed with meteoric water. In combination with regional geology, our new results are suggestive of origin of the Jinchang Cu-Au deposit from contemporary intrusions of granitic porphyries related to the Early Cretaceous subduction of the Paleo-Pacific plate.

  17. Age and evolution of the lithospheric mantle beneath the Khanka Massif: Geochemical and Re-Os isotopic evidence from Sviyagino mantle xenoliths

    Science.gov (United States)

    Guo, Peng; Xu, Wen-Liang; Wang, Chun-Guang; Wang, Feng; Ge, Wen-Chun; Sorokin, A. A.; Wang, Zhi-Wei

    2017-06-01

    New geochemical and Re-Os isotopic data of mantle xenoliths entrained in Cenozoic Sviyagino alkali basalts from the Russian Far East provide insights into the age and evolution of the sub-continental lithospheric mantle (SCLM) beneath the Khanka Massif, within the Central Asian Orogenic Belt (CAOB). These mantle xenoliths are predominantly spinel lherzolites with minor spinel harzburgite. The lherzolites contain high whole-rock concentrations of Al2O3 and CaO, with low forsterite content in olivine (Fo = 89.5-90.3%) and low Cr# in spinel (0.09-0.11). By contrast, the harzburgite is more refractory, containing lower whole rock Al2O3 and CaO contents, with higher Fo (91.3%) and spinel Cr# (0.28). Their whole rock and mineral compositions suggest that the lherzolites experienced low-degree (1-4%) batch melting and negligible metasomatism, whereas the harzburgite underwent a higher degree (10%) of fractional melting, and experienced minor post-melting silicate metasomatism. Two-pyroxene rare earth element (REE)-based thermometry (TREE) yields predominant equilibrium temperatures of 884-1043 °C, similar to values obtained from two-pyroxene major element-based thermometry (TBKN = 942-1054 °C). Two lherzolite samples yield high TREE relative to TBKN (TREE - TBKN ≥ 71 °C), suggesting that they cooled rapidly as a result of the upwelling of hot asthenospheric mantle material that underplated a cold ancient lithosphere. The harzburgite with a low Re/Os value has an 187Os/188Os ratio of 0.11458, yielding an Os model age (TMA) relative to the primitive upper mantle (PUM) of 2.09 Ga, and a Re depletion ages (TRD) of 1.91 Ga; both of which record ancient melt depletion during the Paleoproterozoic ( 2.0 Ga). The 187Os/188Os values of lherzolites (0.12411-0.12924) correlate well with bulk Al2O3 concentrations and record the physical mixing of ancient mantle domains and PUM-like ambient mantle material within the asthenosphere. This indicates that the SCLM beneath the Khanka

  18. Geochemical, mineralogical and Re-Os isotopic constraints on the origin of Tethyan oceanic mantle and crustal rocks from the Central Pontides, northern Turkey

    Science.gov (United States)

    Çelik, Ömer Faruk; Marzoli, Andrea; Marschik, Robert; Chiaradia, Massimo; Mathur, Ryan

    2017-06-01

    Chromite, ultramafic and mafic rocks from Eldivan, Yapraklı, Ayli Dağ, Küre, Elekdağ and Kızılırmak in northern Turkey have been studied to determine their mineral and whole-rock geochemical, and Re-Os isotope geochemical characteristics. Most of the studied peridotites display depleted but commonly V-shaped chondrite-normalized rare-earth element (REE) patterns while some peridotites as well as pyroxenites from all areas exhibit light REE depleted patterns. Olivine (forsterite 82 to 92 mol%) and spinel (chromium number 13 to 63) in the studied peridotites exhibit a wide range of compositions. Compositions of spinels suggest that peridotites from Eldivan, Ayli Dağ and Küre experienced relatively large degrees of partial melting ( 15 and 19 wt%), whereas those of the Kızılırmak area most likely reflect lower melting degrees ( 4-6 wt%). Whole-rock and mineral chemical data indicate that the ultramafic rocks are similar to abyssal and supra-subduction zone peridotites. The ultramafic rocks of the investigated areas exhibit a wide range of 187Re/188Os (0.12 to 6.6) and measured 187Os/188Os (0.122-1.14), while the basaltic rocks from Küre, Eldivan and Kızılırmak areas have high 187Re/188Os (128-562) and measured 187Os/188Os (0.724-1.943). On the other hand, chromite from Eldivan, Elekdağ and Kızılırmak show high Os contents (21.81-44.04 ppb) and low 187Re/188Os (0.015-0.818) and 187Os/188Os (0.122-0.133). Re-Os model ages (TChur) for all analyzed samples yielded scattered ages ranging from Jurassic to Proterozoic. Overall, geochemical data are interpreted to reflect different degrees of partial melting, melt - rock interactions and metasomatic effects that produced a heterogeneous mantle in a supra-subduction setting.

  19. Optimisation of sample preparation protocols for measurement of PGE and Re-Os in organic-rich shales by isotope dilution ICP-MS

    Science.gov (United States)

    Rammensee, Philipp; Aulbach, Sonja; Gudelius, Dominik; Brey, Gerhard

    2013-04-01

    Platinum-group elements (PGE) and Re-Os isotopes, which are variably redox-sensitive and fluid-soluble, have potential as proxies for the oxygenation of the atmosphere and oceans (e.g. [1]). However, analysis of these elements in organic rich shales (ORS) is challenging due to abundances of chromatography is necessary to minimise the effects of interfering elements, but presents its own challenges. We are in the process of conducting variations of acid digestion and column chromatographic protocols on reference sample SDO-1 (Devonian Ohio Shale, USGS). We aim to identify the optimum protocol to investigate PGE-Re-Os systematics of ORS that were sampled as part of the Barberton Drilling Project BARB5 drill core, in order to constrain the changes in detrital and hydrogenous contributions to the sediment with time, to assess the extent of euxinity in the sedimentary basin and to look for evidence of transient "whiffs of oxygen" [1]. The following digestion methods were tested: (1) 4h acid digestion in High Pressure Asher (HPA) apparatus with reverse aqua regia at 300°C and 130 bar (only this digestion allows extraction of volatilised Os in CHCl3 followed by HBr); (2) 3h reverse aqua regia digestion in centrifuge vials on hotplate at 80°C; (3) 48h reverse aqua regia digestion in closed Teflon beakers on hotplate at 140°C followed by a HF/HNO3 digestion step; (4) 48h HF/HNO3 digestion of ashed sample powder in closed Teflon beaker at 140°C on hotplate followed by an aqua regia digestion step. Column chromatographic approaches to decrease the concentrations of interfering elements (Y, Zr, Mo, Cd, Hf, Hg) include the use of cation- and anion resins, and variations of the molarity and composition of the eluent. Preliminary results show that digestion method (1) leaves behind small amounts of presumably PGE-free silica gel; (2) yields consistently higher Re concentrations with an expectedly large amount of solid residue; (3) produces an insoluble sludge; (4) allows

  20. 内蒙古红岭铅锌多金属矿床辉钼矿Re-Os 同位素年龄及其意义%Re-Os Radiometric Dating of Molybdenite in Hongling Lead-Zinc Polymetallic Deposit,Inner Mongolia,and Its Significance

    Institute of Scientific and Technical Information of China (English)

    万多; 李剑锋; 王一存; 王可勇; 王志高; 魏良民

    2014-01-01

    Hongling lead-zinc polymetallic deposit share many similarities with others from the southern Daxinganling poly-metallic metallogenic belt.There are two types of molybdenum mineralization in the mining area,including porphyry and skarn.The former,displaying spot-disseminated feature,occurs in granite porphyry,whereas the latter,displaying film like feature,occurs in quartz.The metallogenic age of Hongling deposit can be constrained from Re-Os isotopic dating of the two kinds of molybdenite.Five samples of spot-disseminated molybdenite yield model ages varying from 139.9±2.3 Ma to 141.5± 3.2 Ma,with an isochron age of 140.3±3.4 Ma (MSWD=0.082),and a weighted average of 140.10±1.80 Ma.The isochron age and weighted average model age are consistent with one another,implying that molybdenum mineralization in Hongling de-posit occurred in Late Jurassic.A film-like molybdenite sample yielded a model age of 143.7±3.6 Ma,representing the initial stage of lead-zinc mineralization.The Re-1 87 Os contents of the film-like molybdenite are higher than that of spot-disseminated molybdeniteby one order of magnitude,which hints that they have different origins and there are two phases of molybdenum mineralization.The characteristics of Re content of the 6 molybdenite samples suggest that the ore-forming elements had a shal-low source,and was mainly derived from the crust.The extremely low content of Re might be du to the low Re content within its parent magma as well as its paragenetic mineral assemblage.Combined with the results of previous study,it is concluded that (a)both rock-and ore-forming materials of Hongling deposit came from hyperplasia crust;and (b)the deposit formed in a dynamical environment of continental crust extension post Mongolia-Okhotsk collisional orogeny.%红岭铅锌多金属矿床为大兴安岭南段多金属成矿带的代表性矿床之一.区内发育斑岩型和矽卡岩型2种钼矿化,前者为产于花岗斑岩内呈斑点-浸染状产出的

  1. An integrated petrological, geochemical and Re-Os isotope study of peridotite xenoliths from the Argyle lamproite, Western Australia and implications for cratonic diamond occurrences

    Science.gov (United States)

    Luguet, A.; Jaques, A. L.; Pearson, D. G.; Smith, C. B.; Bulanova, G. P.; Roffey, S. L.; Rayner, M. J.; Lorand, J.-P.

    2009-11-01

    An integrated study of the petrology and Re-Os geochemistry of a suite of peridotite xenoliths, some carrying abundant diamonds, from the richly diamondiferous Argyle AK1 lamproite pipe provides definitive evidence for a depleted lithospheric root of Neoarchean age (T RD eruption ˜ 2.2-3.1 Ga) beneath the Proterozoic Halls Creek Orogen at the margin of the Kimberley Craton, Western Australia. The microdiamonds from the peridotitic xenoliths are similar in their properties to the minor population of small, commercial sized, peridotitic diamonds from Argyle, both formed in the Archean from isotopically mantle-like carbon. The major element bulk chemistry and mineral chemistry of the Argyle peridotites are slightly less depleted than Archean cratonic peridotites as a whole but similar to those reported from Neoarchean-Paleoproterozoic cratonic provinces. The Argyle peridotite xenoliths were derived from within the diamond stability field (1050-1300 °C and 4.9-5.9 GPa) near the base of the lithosphere (typically 160-200 km depth) with a geothermal gradient of 41.5 mW/m 2. This thick diamondiferous lithosphere, estimated at up to 225 km thick from present day seismic S-wave tomography, appears to have persisted since the time of eruption of the Argyle lamproite (˜ 1180 Ma). The existence of late Archean age lithosphere beneath the Argyle diamond pipe, in a region where no crustal rocks of Archean age are known, suggests a decoupling of the crust and mantle in the region of the Halls Creek Orogen, perhaps as a consequence of Paleoproterozoic (˜ 1.85 Ga) reworking and/or subduction at the margin of the Kimberley Craton. The confirmation of an Archean lithospheric root beneath the Argyle pipe at the margin of the Kimberley Craton seemingly conforms with "Clifford's Rule", regarding the restriction of economic diamond deposits to those underlain by Archean cratons. However, Argyle owes its rich diamond grades not to its Neoarchean mantle roots but to the presence of

  2. Genesis of the Datuanshan stratabound skarn Cu(-Mo) deposit, Middle-Lower Yangtze Valley, Eastern China: constraints from geology, Re-Os geochronology, mineralogy, and sulfur isotopes

    Science.gov (United States)

    Cao, Yi; Gao, Fuping; Du, Yangsong; Du, Yilun; Pang, Zhenshan

    2016-07-01

    Stratabound deposits are the most abundant and economically significant ore type in the Middle-Lower Yangtze River Valley, one of the most important metallogenic belts in China. The Datuanshan deposit is one of the largest and most representative stratabound Cu(-Mo) deposits in the Tongling district of the Middle-Lower Yangtze River metallogenic belt. All the orebodies of the Datuanshan deposit occur around Mesozoic quartz monzodiorite and are tabular or semi-tabular bodies along bedding-parallel faults within upper Permian to Lower Triassic strata. However, discordant and crosscutting relationships (e.g., the host rocks crosscut by skarn- and quartz-sulfide veins, with alteration halos around the veins) have also been found, especially along the skarn-host contact and orebody-host contact, indicating that skarnitization and mineralization postdated the deposition of the host sediments. The skarn consists mainly of prograde garnet and pyroxene and retrograde alteration assemblages of amphibole, epidote, and chlorite, as well as quartz and sulfides. Electron microprobe analyses show that the garnets and pyroxenes are grossular-andradite and hedenbergite-diopside series, respectively, and all samples plot in the field of typical skarn copper deposits worldwide. Molybdenite samples from stratiform copper ores yield Re-Os model ages of 138.2-139.9 Ma with a weighted mean age of 139.2 ± 0.9 Ma. This is reasonably consistent with the ages of the stratiform Mo ores (138.0-140.8 Ma) and genetically related quartz monzodiorite (135.2-139.3 Ma) in the Datuanshan deposit, indicating that the stratiform Cu and Mo mineralization was contemporaneous with emplacement of the quartz monzodiorite magmas in the Early Cretaceous. Fifteen δ34S values for sulfides range from -1.8 to +4.7 ‰, with a mean of 0.5 ‰, indicating that the sulfur was derived mainly from a magmatic source. Moreover, the sulfur isotope values of the ores are consistent with those of Mesozoic intermediate

  3. Zircon U-Pb and molybdenite Re-Os geochronology and Sr-Nd-Pb-Hf isotopic constraints on the genesis of the Xuejiping porphyry copper deposit in Zhongdian, Northwest Yunnan, China

    Science.gov (United States)

    Leng, Cheng-Biao; Zhang, Xing-Chun; Hu, Rui-Zhong; Wang, Shou-Xu; Zhong, Hong; Wang, Wai-Quan; Bi, Xian-Wu

    2012-10-01

    The Xuejiping porphyry copper deposit is located in northwestern Yunnan Province, China. Tectonically, it lies in the southern part of the Triassic Yidun island arc. The copper mineralization is mainly hosted in quartz-dioritic and quartz-monzonitic porphyries which intruded into clastic-volcanic rocks of the Late Triassic Tumugou Formation. There are several alteration zones including potassic, strong silicific and phyllic, argillic, and propylitic alteration zones from inner to outer of the mineralized porphyry bodies. The ages of ore-bearing quartz-monzonitic porphyry and its host andesite are obtained by using the zircon SIMS U-Pb dating method, with results of 218.3 ± 1.6 Ma (MSWD = 0.31, N = 15) and 218.5 ± 1.6 Ma (MSWD = 0.91, N = 16), respectively. Meanwhile, the molybdenite Re-Os dating yields a Re-Os isochronal age of 221.4 ± 2.3 Ma (MSWD = 0.54, N = 5) and a weighted mean age of 219.9 ± 0.7 Ma (MSWD = 0.88). They are quite in accordance with the zircon U-Pb ages within errors. Furthermore, all of them are contemporary with the timing of the Garzê-Litang oceanic crust subduction in the Yidun arc. Therefore, the Xuejiping deposit could be formed in a continental margin setting. There are negative ɛNd(t) values ranging from -3.8 to -2.1 and relatively high initial 87Sr/86Sr ratios from 0.7051 to 0.7059 for the Xuejiping porphyries and host andesites. The (206Pb/204Pb)t, (207Pb/204Pb)t and (208Pb/204Pb)t values of the Xuejiping porphyries and host andesites vary from 17.899 to 18.654, from 15.529 to 15.626, and from 37.864 to 38.52, respectively, indicative of high radiogenic Pb isotopic features. In situ Hf isotopic analyses on zircons by using LA-MC-ICP-MS exhibit that there are quite uniform and slightly positive ɛHf(t) values ranging from -0.2 to +3.2 (mostly between 0 and +2), corresponding to relatively young single-stage Hf model ages from 735 Ma to 871 Ma. These isotopic features suggest that the primary magmas of the Xuejiping porphyries and

  4. New constraints on the Paleoarchean meteorite bombardment of the Earth - Geochemistry and Re-Os isotope signatures of spherule layers in the BARB5 ICDP drill core from the Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Schulz, Toni; Koeberl, Christian; Luguet, Ambre; van Acken, David; Mohr-Westheide, Tanja; Ozdemir, Seda; Reimold, Wolf Uwe

    2017-08-01

    Archean spherule layers, resulting from impacts by large extraterrestrial objects, to date represent the only remnants of the early meteorite, asteroid, and comet bombardment of the Earth. Only few Archean impact debris layers have been documented, all of them embedded in the 3.23-3.47 billion year old successions of the Barberton Greenstone Belt (BGB) in South Africa and the Pilbara Craton in Western Australia. Some of them might be correlated with each other. Given the scarcity of Archean spherule deposits, four spherule layer intersections from the recently recovered BARB5 drill core from the central Barberton Greenstone Belt, analyzed in this study, provide an opportunity to gain new insight into the early terrestrial impact bombardment. Despite being hydrothermally overprinted, siderophile element abundance signatures of spherule-rich samples from the BARB5 drill core, at least in part, retained a meteoritic fingerprint. The impact hypothesis for the generation of the BARB5 spherule layers is supported by correlations between the abundances of moderately (Cr, Co, Ni) and highly siderophile (Re, Os, Ir, Pt, Ru and Pd) elements, whose peak concentrations and interelement ratios are within the range of those for chondrites. Rhenium-Osmium isotope evidence further support the impact hypothesis. Collectively, this study provides evidence for extraterrestrial admixtures ranging between ∼40 and up to 100% to three of the four analyzed BARB5 spherule layers, and a scenario for their genesis involving (i) impact of a chondritic bolide into a sedimentary target, (ii) varying admixtures of meteoritic components to target materials, (iii) spherule formation via condensation in an impact vapor plume, (iv) transportation of the spherules and sedimentation under submarine conditions, followed by (v) moderate post-impact remobilization of transition metals and highly siderophile elements.

  5. 沥青样品铼-锇同位素分析溶解实验研究%Dissolving Experimental Research of Re-Os Isotope System for Bitumen Samples

    Institute of Scientific and Technical Information of China (English)

    李超; 屈文俊; 王登红; 陈郑辉; 杜安道; 张长青

    2011-01-01

    The content of Re-Os in asphalt samples is relatively low, and CO2 are released in digestion because of large amounts of organic matter. It is important to control the amount of asphalt in the sample and the proportion of oxidant to ensure the Os recovery and stability of the measured signal. The method for the Re-Os isotope was improved because of large amounts of organic matter contained in bitumen samples. The Oxidants was changed to 3 mL HC1, 4 mL HNO3 and 3mL H2 O2 from the original 3 mL HC1 and 6 mL HNO3, the improved method making the Os measured signal approximately 2 times larger than before. Changes in oxidants composition increase the amount of the bitumen sample weight greatly from th eoriginal 0.2 g to 0. 4 g. Influence of H2 O2 added with routine reverse aqua regia and direct distillation from a Carius tube on the signal intensity of osmium measured by Inductively Coupled Plasma-MassSpectrometry( ICP-MS ). Was studied. Bitumen samples were dissolved and equilibrated with a known amount of 185Re and 190Os tracers in 2 mL HC1, 5 mL HNO3 and 2 mL H2O2 by a Carius tube at 200℃ for 12 h and 240℃ for 12 h, with the Os and Re separated using direct distillation or routine distillation and solvent extraction techniques, respectively. 187Re/185 Re, 187Os/190Os and 192Os/190Os were determined by ICP-MS. Bitumen samples in lead-zinc deposits from Yunnan Province were analyzed. The isochron ages was (60 ± 2 ) Ma ( MSWD = 2. 5, n = 7 ), and the initial 187Os/188Os values was 4. 36 ±0. 14. The results show that Re-Os isotope is an effective tool to date bitumen samples and the Os in the bitumen originated from the crust. The established method can be used to date and trace the source of bitumen samples.%沥青样品中Re、Os含量较低,且组成复杂,因含有大量有机质,在溶样过程中会释放大量CO2,需要大量氧化剂.控制样品称样量和氧化剂比例、用量对保证Os的回收率以及测量信号的稳定性非常重要.本文根

  6. In-situ U-Pb, Hf and Re-Os isotopic analyses of the Xiangshan Ni-Cu-Co deposit in Eastern Tianshan (Xinjiang), Central Asia Orogenic Belt: Constraints on the timing and genesis of the mineralization

    Science.gov (United States)

    Han, Chunming; Xiao, Wenjiao; Zhao, Guochun; Ao, Songjian; Zhang, Jien; Qu, Wenjun; Du, Andao

    2010-12-01

    The timing and genesis of the major Ni-Cu-Co sulfide deposit in the Xiangshan intrusion have been studied based on newly obtained in-situ U-Pb, Hf and Re-Os isotopic analyses. The SIMS U-Pb zircon ages of the gabbro hosting the Ni-Cu-Co sulfide deposit indicate that the Xiangshan intrusion was emplaced at 279.6 ± 1.1 Ma (95% confidence level, MSWD = 1.30, n = 15). On the basis of combined geological and geochronological evidence, we suggest that the Xiangshan and other adjacent Ni-Cu deposits were formed in the same period. Sulphides have low common Os concentrations and high Re/Os ratios, similar to sulphide ores from the Duluth, Sally Malay and Voisey Bay complexes. The Re-Os isotopic data from the disseminated and massive ores from the Xiangshan intrusion do not form a single isochron, as they have different initial Os ratios. The Hf and Os isotopic data suggest that the Xiangshan intrusion and associated Ni-Cu-Co mineralization were derived from crustally contaminated mantle melts. The geochemical data show a tholeiitic affinity and a strong suprasubduction zone signature with negative Nb, Sr, and Ti anomalies similar to N-MORB and E-MORB. We suggest that the mafic-ultramafic rocks and associated Ni-Cu mineralization of the Eastern Tianshan orogen formed in an Alaska-type subduction zone-arc setting. Some diagnostic features of ridge-trench interaction are present in the Chinese East Tianshan orogen (e.g. granites, adakites, high-Mg andesites, near-trench magmatism, Alaskan-type mafic-ultramafic complexes, high-temperature metamorphic belts that prograde rapidly from low-grade belts, and orogenic gold deposits). The above distinctive rock groups are probably related to the same thermal event, ridge subduction, as in the Cenozoic orogen of Alaska. We suggest that ridge subduction is the most plausible mechanism to provide the necessary heat. Ridge subduction provides an important promising model for understanding many aspects of the evolution of the Chinese

  7. Tungsten isotopic compositions in stardust SiC grains from the Murchison meteorite: Constraints on the s-process in the Hf-Ta-W-Re-Os region

    CERN Document Server

    Ávila, J N; Ireland, T R; Gyngard, F; Zinner, E; Cristallo, S; Holden, P; Buntain, J; Amari, S; Karakas, A

    2011-01-01

    We report the first tungsten isotopic measurements in stardust silicon carbide (SiC) grains recovered from the Murchison carbonaceous chondrite. The isotopes 182W, 183W, 184W, 186W and 179Hf, 180Hf were measured on both an aggregate (KJB fraction) and single stardust SiC grains (LS+LU fraction) believed to have condensed in the outflows of low-mass carbon-rich asymptotic giant branch (AGB) stars with close-to-solar metallicity. The SiC aggregate shows small deviations from terrestrial (=solar) composition in the 182W/184W and 183W/184W ratios, with deficits in 182W and 183W with respect to 184W. The 186W/184W ratio, however, shows no apparent deviation from the solar value. Tungsten isotopic measurements in single mainstream stardust SiC grains revealed lower than solar 182W/184W, 183W/184W, and 186W/184W ratios. We have compared the SiC data with theoretical predictions of the evolution of W isotopic ratios in the envelopes of AGB stars. These ratios are affected by the slow neutron-capture process and match...

  8. TUNGSTEN ISOTOPIC COMPOSITIONS IN STARDUST SiC GRAINS FROM THE MURCHISON METEORITE: CONSTRAINTS ON THE s-PROCESS IN THE Hf-Ta-W-Re-Os REGION

    Energy Technology Data Exchange (ETDEWEB)

    Avila, Janaina N.; Ireland, Trevor R.; Holden, Peter [Research School of Earth Sciences, Australian National University, Canberra, ACT 0200 (Australia); Lugaro, Maria; Buntain, Joelene [Centre for Stellar and Planetary Astrophysics, Monash University, Clayton, VIC 3800 (Australia); Gyngard, Frank; Zinner, Ernst; Amari, Sachiko [Laboratory for Space Sciences and the Department of Physics, Washington University, One Brookings Drive, St. Louis, MO 63130 (United States); Cristallo, Sergio [Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, Granada 18071 (Spain); Karakas, Amanda, E-mail: janaina.avila@anu.edu.au [Mount Stromlo Observatory, Australian National University, Weston Creek, ACT 2611 (Australia)

    2012-01-01

    We report the first tungsten isotopic measurements in stardust silicon carbide (SiC) grains recovered from the Murchison carbonaceous chondrite. The isotopes {sup 182,183,184,186}W and {sup 179,180}Hf were measured on both an aggregate (KJB fraction) and single stardust SiC grains (LS+LU fraction) believed to have condensed in the outflows of low-mass carbon-rich asymptotic giant branch (AGB) stars with close-to-solar metallicity. The SiC aggregate shows small deviations from terrestrial (= solar) composition in the {sup 182}W/{sup 184}W and {sup 183}W/{sup 184}W ratios, with deficits in {sup 182}W and {sup 183}W with respect to {sup 184}W. The {sup 186}W/{sup 184}W ratio, however, shows no apparent deviation from the solar value. Tungsten isotopic measurements in single mainstream stardust SiC grains revealed lower than solar {sup 182}W/{sup 184}W, {sup 183}W/{sup 184}W, and {sup 186}W/{sup 184}W ratios. We have compared the SiC data with theoretical predictions of the evolution of W isotopic ratios in the envelopes of AGB stars. These ratios are affected by the slow neutron-capture process and match the SiC data regarding their {sup 182}W/{sup 184}W, {sup 183}W/{sup 184}W, and {sup 179}Hf/{sup 180}Hf isotopic compositions, although a small adjustment in the s-process production of {sup 183}W is needed in order to have a better agreement between the SiC data and model predictions. The models cannot explain the {sup 186}W/{sup 184}W ratios observed in the SiC grains, even when the current {sup 185}W neutron-capture cross section is increased by a factor of two. Further study is required to better assess how model uncertainties (e.g., the formation of the {sup 13}C neutron source, the mass-loss law, the modeling of the third dredge-up, and the efficiency of the {sup 22}Ne neutron source) may affect current s-process predictions.

  9. Combined Whole-Rock to Nano-Scale Investigations Reveal Contrasting Response of Pt-Os and Re-Os Isotope Systematics During Magmatic and Post-Magmatic Processes

    Science.gov (United States)

    Coggon, J. A.; Luguet, A.; Lorand, J. P.; Fonseca, R.; Wainwright, A.; Appel, P.; Hoffmann, J. E.; Nowell, G. M.

    2015-12-01

    Advances in single-grain and micro- and nano-analytical techniques in recent years have been particularly important to the study of highly siderophile elements (HSE) and have contributed significantly to our knowledge and understanding of their host phases and behaviour. Furthermore, whole-rock- to nano-scale studies provide new perspectives for investigation of HSE isotope systematics. Recent multi-scale 187Re-187Os and 190Pt-186Os studies facilitate comparison, to a previously unattainable degree, of the differing responses of these two decay systems to magmatic and post-magmatic processes. It is well established that mafic-ultramafic melts are sensitive to disturbance of their Re-Os isotope systematics by crustal assimilation, due to the incompatibility and resulting enrichment of Re in crustal lithologies. In contrast the very long half-life and extremely low atomic abundance of 190Pt, combined with relatively low Pt concentrations in crustal rocks, generally render the Pt-Os isotope system insensitive to modification during assimilation. However, using new single chromite grain data (Coggon et al., 2015) from the >3.811 Ga Ujaragssuit nunât layered ultramafic body, Greenland, we show that it is possible to distinguish two distinct episodes of 187Os/188Os modification; Country rock contamination of the parent melt was followed by later metamorphic disturbance of the isotope system. The Pt-Os data (Coggon et al., 2013) from the same samples show no evidence of crustal assimilation, but preserve signatures of mantle melting at ~4.1 Ga as well as disturbance during metamorphism. Macro- to micro-petrographic study clearly demonstrates that Pt, Re and Os are hosted by different mineral phases, of different origins, in these samples. This, together with the physical parameters of the decay systems reported above, leads to the dissimilar behaviour and response of the 187Re-187Os and 190Pt-186Os isotope systems during both magmatic and post-magmatic processes and

  10. SHRIMP zircon U-Pb and Re-Os dating of No. 10 intrusive body and associated ores in Pobei mafic-ultramafic belt of Xinjiang and its significance%新疆坡北基性-超基性岩带10号岩体SHRIMPU-Pb和矿石Re-Os同位素定年及其意义

    Institute of Scientific and Technical Information of China (English)

    李华芹; 梅玉萍; 屈文俊; 蔡红; 杜国民

    2009-01-01

    Located in Beishan rift in the northeastern part of Tarim plate, the Pobei No. 10 mafic-ultramafic body in-truded into Early Carboniferous Hongliuyuan Formation. It is large in size and well differentiated, thus serving as one of the most important intrusive bodies in search for copper-nickel sulfides. According to its emplacement strata, it was previously thought that this intrusive body was formed in Late Carboniferous-Early Permian. The uthors performed dating by using such techniques as zircon U-Pb, disseminated ores Re-Os and Sr-Nd isotopic tracer with the purpose of systematic determination of the magmatie and mineralization ages, on such a basis, discussed the metallogenic significance of systematic differences between the ages dated by different isotopic sys-tems. Radiometric dating of the gabbro from the Pobei No. 10 mafic-ultramafie body yielded rather scattered zir-con age information, but obtained a main body zircon SHRIMP U-Pb age of (289± 13)Ma(95 % confidence, MSWD=4.9, n = 8), which is interpreted as the formation age of the host intrusive. The disseminated ores give an apparent Re-Os isochron age of (413 ± 20) Ma with an initial 187Os/188Os ratio of (0.226 ± 0.032). However, it is found that the apparent Re-Os isochron ages of disseminated ores are older than both the forma-tion age of the host intrusions and the ages of Pobei No. 10 mafic-ultramafic emplacement strata, which indicates that the apparent Re-Os isochron ages of disseminated ores are not reliable. It is suggested that the Pobei No. 10 mafic-ultramafic body and the deposit were formed at about 280 Ma ago. Because of heterogeneity in initial ~(187)Os/~(188)Os ratios of disseminated ores caused by crust contamination, the apparent dates older than the true age were obtained. Cu-Ni mineraliztion shows a close time-space relationship with the mafic-ultramafic intrusive body, implying a product of magmatic liquation. It is therefore concluded that the intrusion of Pobei No. 10 mafic

  11. Re-Os dating of mineralization in Siah Kamar porphyry Mo deposit (NW Iran) and investigating on its temporal relationship with porphyry Cu-Mo deposits in the southern Lesser Caucasus, NW and central Iran

    Science.gov (United States)

    Simmonds, Vartan; Moazzen, Mohssen; Selby, David

    2017-04-01

    The Neo-Tethyan basin closure in Iran is characterized by the Urumieh-Dokhtar magmatic arc (UDMA), formed by north-eastward subduction of the Neo-Tethyan oceanic crust during the Alpine orogeny. This belt also coincides with the porphyry copper metallogenic belt of Iran, which hosts many porphyry Cu-Mo deposits (PCDs) and prospects, such as Sungun (NW Iran) and Sarcheshmeh (central Iran). The Siah Kamar porphyry Mo deposit (PMD) is the first discovered porphyry molybdenum deposit on this belt, which is located 10 km west of Mianeh (NW Iran), with 39.2 Mt proved reserves @ 539 ppm Mo and 66.4 Mt probable reserves @ 266 ppm Mo. The host porphyry stock has quartz-monzonitic composition, which intruded the volcanic and pyroclastic rocks of Eocene age. Re content of molybdenites is about 10.44-41.05 ppm which, considering the several tens of ppm concentration, is comparable with porphyry Mo deposits (e.g., Climax in USA), being clearly distinguished from porphyry Cu-Mo deposits. Re-Os dating of molybdenites from this PMD has given model ages between 28.1±0.15 to 29.06±0.2 Ma, and isochron age of 28.0±2.1 Ma, corresponding to the middle Oligocene (upper part of Rupelian). Comparing the ages determined for Siah Kamar PMD with porphyry Cu-Mo mineralizations in the Lesser Caucasus indicates that it is younger than most of the dated PCDs and prospects there, especially those of upper Eocene, while it is a little older than Paragachay and first-stage Kadjaran PCDs [1]. In a regional scale of NW Iran, it shows a narrow overlap with vein-type Cu-Mo-Au mineralizations in Qarachilar (Qaradagh batholith) and is nearly coeval with Haftcheshmeh PCD, indicating that mineralization in the Siah Kamar PMD corresponds to the second porphyry mineralization epoch in NW Iran, proposed by [2]. Meanwhile, mineralization in Siah Kamar is older than all the porphyry Cu-Mo mineralizations along the central and SE parts of the UDMA, except the Bondar Hanza PCD in Kerman zone, which nearly

  12. 菲莫铜钼多金属矿床Re-Os同位素年龄及其成矿环境%Re-Os ISOTOPIC AGES OF FEIMO Cu-Mo POLYMETALLIC DEPOSITS AND THE IRGEODYNAMIC SETTINGS

    Institute of Scientific and Technical Information of China (English)

    吴自成; 刘继顺; 张彩华; 舒国文; 王伟

    2011-01-01

    菲莫铜钼多金属矿床是哀牢山造山带内较典型的铜钼多金属矿床,研究采用电感耦合等离子体质谱仪法对菲莫铜钼多金属矿床辉钼矿的Re-Os同位素精确测年,获得辉钼矿Re-Os同位素模式年龄为47.81 Ma±0.71 Ma;而哀牢山铜多金属成矿带镇沅、墨江、大坪大型金矿的成矿时间均与之相当,约50 Ma±.这暗示了喜马拉雅期由于印度板块向北碰撞,造成古特提斯洋消失,碰撞造山过程导致上地幔及下地壳等深部物质部分熔融,红河、哀牢山走滑挤压引起的热流值上升造成了深熔作用导致地壳深部物质进一步熔融,造成了哀牢山带大规模的构造-岩浆热事件,从而为形成诸多铜、金及多金属矿床提供了大量的成矿物质和动力、热流条件.%ICP-MS method is used to study the Re-Os isotopes for molybdenite samples of Feimo Cu-Mo polymetallic deposit. It is revealed that the ore-forming age is 47. 81 + 0. 71Ma on average, similar to the gold deposit mineralization time (50 Mai) of Zhenyuan, Mojiang and Daping in Ailaoshan area. It indicates that northward subduction of Indian Plate under the Euro-Asia Plate in Himalayan resulted in the closet of Paleo-Tethys ocean,and during the collision orogeny,the deep material in upper mantle and lower crust are partly melting. Large-scale tectonic and mag-matic activities occurred in Ailaoshan belt duo to the strike-slip and compression and brought a-bout the melting of material of deep crust and the uplift of thermal flow, which provided driving force,hydrothermal fluid and a lot of ore-forming materials,forming plenty of polymetallic ore deposits.

  13. GEOCHRONOMETRY &ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131727 Huang Xiaowen(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550002,China);Qi Liang Preliminary Study on Sample-Preparation for Re-Os Isotopic Dating of Pyrite(Geochimica,ISSN0379-1726,CN44-1398/P,41(4),2012,p.380-386,3illus.,2tables,25refs)Key words:pyrite,Re-Os dating

  14. Direct radiometric dating of hydrocarbon deposits using rhenium-osmium isotopes.

    Science.gov (United States)

    Selby, David; Creaser, Robert A

    2005-05-27

    Rhenium-osmium (Re-Os) data from migrated hydrocarbons establish the timing of petroleum emplacement for the giant oil sand deposits of Alberta, Canada, at 112 +/- 5.3 million years ago. This date does not support models that invoke oil generation and migration for these deposits in the Late Cretaceous. Most Re-Os data from a variety of deposits within the giant hydrocarbon system show similar characteristics, supporting the notion of a single source for these hydrocarbons. The Re-Os data disqualify Cretaceous rocks as the primary hydrocarbon source but suggest an origin from older source rocks. This approach should be applicable to dating oil deposits worldwide.

  15. Re-Os geochronology and Os isotope fingerprinting of petroleum sourced from a Type I lacustrine kerogen: insights from the natural Green River petroleum system in the Uinta Basin and hydrous pyrolysis experiments

    Science.gov (United States)

    Cumming, Vivien M.; Selby, David; Lillis, Paul G.; Lewan, Michael D.

    2014-01-01

    Rhenium–osmium (Re–Os) geochronology of marine petroleum systems has allowed the determination of the depositional age of source rocks as well as the timing of petroleum generation. In addition, Os isotopes have been applied as a fingerprinting tool to correlate oil to its source unit. To date, only classic marine petroleum systems have been studied. Here we present Re–Os geochronology and Os isotope fingerprinting of different petroleum phases (oils, tar sands and gilsonite) derived from the lacustrine Green River petroleum system in the Uinta Basin, USA. In addition we use an experimental approach, hydrous pyrolysis experiments, to compare to the Re–Os data of naturally generated petroleum in order to further understand the mechanisms of Re and Os transfer to petroleum. The Re–Os geochronology of petroleum from the lacustrine Green River petroleum system (19 ± 14 Ma – all petroleum phases) broadly agrees with previous petroleum generation basin models (∼25 Ma) suggesting that Re–Os geochronology of variable petroleum phases derived from lacustrine Type I kerogen has similar systematics to Type II kerogen (e.g., Selby and Creaser, 2005a, Selby and Creaser, 2005b and Finlay et al., 2010). However, the large uncertainties (over 100% in some cases) produced for the petroleum Re–Os geochronology are a result of multiple generation events occurring through a ∼3000-m thick source unit that creates a mixture of initial Os isotope compositions in the produced petroleum phases. The 187Os/188Os values for the petroleum and source rocks at the time of oil generation vary from 1.4 to 1.9, with the mode at ∼1.6. Oil-to-source correlation using Os isotopes is consistent with previous correlation studies in the Green River petroleum system, and illustrates the potential utility of Os isotopes to characterize the spatial variations within a petroleum system. Hydrous pyrolysis experiments on the Green River Formation source rocks show that Re and Os transfer

  16. The Re-Os isotope system of the Xiongcun porphyry copper-gold deposit, Tibet%西藏雄村斑岩铜矿床辉钼矿Re-Os同位素体系

    Institute of Scientific and Technical Information of China (English)

    黄勇; 唐菊兴; 丁俊; 张丽; 郎兴海

    2013-01-01

    辉钼矿Re-Os同位素测年是现今研究斑岩铜矿成矿时限最有效的手段.本文通过开展冈底斯成矿带雄村斑岩铜金矿辉钼矿Re-Os同位素年代学研究,并结合前人已发表的数据,认为雄村斑岩铜金矿床成矿时限为171~175Ma.Ⅰ号矿体可能受到始新世大规模的岩浆活动扰动,辉钼矿在经历过后期热事件影响,在辉钼矿中形成有极微量富Re的K-硅酸盐矿物,Ⅰ号矿体辉钼矿Re含量比Ⅱ号矿体以及Ⅲ号矿体中辉钼矿Re含量高出1~4倍,其Re-Os同位素年龄比真实年龄偏低,不能完全代表成矿年龄.同时通过与冈底斯成矿带斑岩-矽卡岩铜钼矿床,钼/钼铜矿床的对比研究后发现,雄村斑岩铜金矿中辉钼矿Re含量比同一成矿带上中新世斑岩铜钼矿床中辉钼矿Re含量高出一个数量级,比古新世—始新世斑岩钼矿/钼铜矿床中辉钼矿Re含量高出两个数量级.辉钼矿Re含量变化特征与成矿物质的来源、钼的浓度、成矿母岩组分以及成矿期间的物理/化学条件有关.%Re-Os dating of molybdenite is an efficient means to restrict the time of mineralization. The age of mineralization of the Xiongcun porphyry copper-gold deposit is confined between 171 Ma and 175 Ma based on this study and other data available. No. Ⅰ ore body of the Xiongcun deposit was affected by later magmtic thermal event. Molybdenite contains trace K-Si silicate enriched in Re. As a result of this event, the Re content of molybdenite is one to four times higher than that of molybdenite in No.Ⅱ ore body and No. Ⅲ ore body, and the age of molybdenite in No. Ⅰ ore body is younger than the real age. The authors also compared the Re content of molybdenite between this deposit and other porphyry-skarn deposits within this belt and found that the content of Re shows systematic variation. The Re content of the Xiongcun porphyry copper-gold deposit is one order of magnitude high than that of Miocene

  17. Re/Os cosmochronometer: measurement of neutron cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Mosconi, M.

    2007-12-21

    This experimental work is devoted to the improved assessment of the Re/Os cosmochronometer. The dating technique is based on the decay of {sup 187}Re (t{sub 1/2}=41.2 Gyr) into {sup 187}Os and determines the age of the universe by the time of onset of nucleosynthesis. The nucleosynthesis mechanisms, which are responsible for the {sup 187}Re/{sup 187}Os pair, provide the possibility to identify the radiogenic fraction of {sup 187}Os exclusively by nuclear physics considerations. Apart from its radiogenic component, {sup 187}Os can be synthesized otherwise only by the s process, which means that this missing fraction can be reliably determined and subtracted by proper s-process modeling. On the other hand, {sup 187}Re is almost completely produced by the r process. The only information needed for the interpretation as a cosmic clock is the production rate of {sup 187}Re as a function of time. The accuracy of the s-process calculations that are needed to determine the nucleosynthetic abundance of {sup 187}Os depends on the quality of the neutron capture cross sections averaged over the thermal neutron spectrum at the s-process sites. Laboratory measurements of these cross sections have to be corrected for the effect of nuclear levels, which can be significantly populated at the high stellar temperatures during the s process. The neutron capture cross sections of {sup 186}Os, {sup 187}Os and {sup 188}Os have been measured at the CERN n TOF facility in the range between 0.7 eV and 1 MeV. From these data, Maxwellian averaged cross sections have been determined for thermal energies from 5 to 100 keV with an accuracy around 4%, 3%, and 5% for {sup 186}Os, {sup 187}Os, and {sup 188}Os, respectively. Since, the first excited state in {sup 187}Os occurs at 9.75 keV, the cross section of this isotope requires a substantial correction for thermal population of low lying nuclear levels. This effect has been evaluated on the basis of resonance data derived in the (n, {gamma

  18. Re/Os cosmochronometer: measurement of neutron cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Mosconi, M.

    2007-12-21

    This experimental work is devoted to the improved assessment of the Re/Os cosmochronometer. The dating technique is based on the decay of {sup 187}Re (t{sub 1/2}=41.2 Gyr) into {sup 187}Os and determines the age of the universe by the time of onset of nucleosynthesis. The nucleosynthesis mechanisms, which are responsible for the {sup 187}Re/{sup 187}Os pair, provide the possibility to identify the radiogenic fraction of {sup 187}Os exclusively by nuclear physics considerations. Apart from its radiogenic component, {sup 187}Os can be synthesized otherwise only by the s process, which means that this missing fraction can be reliably determined and subtracted by proper s-process modeling. On the other hand, {sup 187}Re is almost completely produced by the r process. The only information needed for the interpretation as a cosmic clock is the production rate of {sup 187}Re as a function of time. The accuracy of the s-process calculations that are needed to determine the nucleosynthetic abundance of {sup 187}Os depends on the quality of the neutron capture cross sections averaged over the thermal neutron spectrum at the s-process sites. Laboratory measurements of these cross sections have to be corrected for the effect of nuclear levels, which can be significantly populated at the high stellar temperatures during the s process. The neutron capture cross sections of {sup 186}Os, {sup 187}Os and {sup 188}Os have been measured at the CERN n TOF facility in the range between 0.7 eV and 1 MeV. From these data, Maxwellian averaged cross sections have been determined for thermal energies from 5 to 100 keV with an accuracy around 4%, 3%, and 5% for {sup 186}Os, {sup 187}Os, and {sup 188}Os, respectively. Since, the first excited state in {sup 187}Os occurs at 9.75 keV, the cross section of this isotope requires a substantial correction for thermal population of low lying nuclear levels. This effect has been evaluated on the basis of resonance data derived in the (n, {gamma

  19. A gallery of oil components, their metals and Re-Os signatures

    Science.gov (United States)

    Stein, Holly J.; Hannah, Judith L.

    2016-04-01

    H are part of the equation controlling composition of metal-bearing aqueous fluids siphoned from residual hydrocarbons. The Re-Os isotopic behavior of oil components is generally specific to location and may differ within a single oil field, or even within discrete fractions of a single sample of oil [1]. Different fractions in a crude oil, for example maltenes and asphaltenes, can preserve signatures of unique sources. This should not be surprising, since economic geologists have long called upon meeting and mixing of metal-bearing with sulfur-bearing fluids from different sources. A time-integrated geologic history can also be derived from bitumen veins, with the Re-Os age of the metal source cached in these veins. Preservation of early metal and hydrocarbon history, and intact Re-Os systematics preserved in younger-formed systems have enormous potential for the resource industry. Several examples will be presented. [1] Georgiev, S.V., Stein, H.J., Hannah, J.L., Galimberti, R., Nali, M., Yang, G., and Zimmerman, A. (returned post revision, 11 Jan 2016) Re-Os dating of maltenes and asphaltenes within single samples of crude oils: Geochimica et Comochimica Acta. Supported by a consortium of petroleum companies under the CHRONOS project.

  20. The Re/Os Clock Revisited

    CERN Multimedia

    Leal, L C; Kitis, G; Guber, K H; Quaranta, A; Koehler, P E

    2002-01-01

    The purpose of the proposed project of an accurate measurement of the relevant neutron cross sections of $^{186}$Os and $^{187}$Os is to remove the principal nuclear physics uncertainties in the analysis of the Re/Os cosmochronometer. The necessary cross section information will be obtained in complementary experiments at the nTOF facility at CERN and at the Karlsruhe Van de Graaff accelerator. Transformation of these results into significantly improved stellar reaction rates will allow to evaluate the age of the elements in the framework of galactic chemical evolution models.

  1. Molybdenite Re/Os dating, zircon U-Pb age and geochemistry of granitoids in the Yangchuling porphyry W-Mo deposit (Jiangnan tungsten ore belt), China: Implications for petrogenesis, mineralization and geodynamic setting

    Science.gov (United States)

    Mao, Jingwen; Xiong, Bikang; Liu, Jun; Pirajno, Franco; Cheng, Yanbo; Ye, Huishou; Song, Shiwei; Dai, Pan

    2017-08-01

    The Yangchuling W-Mo deposit, located in the Jiangnan porphyry-skarn (JNB) tungsten ore belt, is the first recognized typical porphyry W-Mo deposit in China in the 1980's. Stockworks and disseminated W-Mo mineralization occur in the roof pendant of a 0.3 km2 monzogranitic porphyry stock that intruded into a granodiorite stock, hosted by Neoproterozoic phyllite and slate. LA-ICPMS zircon U-Pb analyses suggest that of the monzogranitic porphyry and granodiorite were formed at 143.8 ± 0.5 Ma and 149.8 ± 0.6 Ma, respectively. Six molybdenite samples yielded a Re-Os weighted mean age of 146.4 ± 1.0 Ma. Geochemical data show that both granodiorite and monzogranitic porphyry are characterized by enrichment of large ion lithophile elements (LILE) relative to high field strength elements (HFSE), indicating a peraluminous nature (A/CNK = 1.01-1.08). Two granitoids are characterized by a negative slope with significant light REE/heavy REE fractionation [(La/Yb)N = 8.38-23.20] and negative Eu anomalies (Eu/Eu* = 0.69-0.76). The P2O5 contents of the Yangchuling granitoids range from 0.12% to 0.17% and exhibit a negative correlation with SiO2, reflecting that they are highly fractionated I-type. They have high initial 87Sr/86Sr ratios (0.7104-0.7116), low negative εNd(t) (- 5.05 to - 5.67), and homogeneous εHf(t) between - 1.39 and - 2.17, indicating similar sources. Additionally, two-stage Nd model ages (TDM2) of 1.3-1.4 Ga and two-stage Hf model ages (TDM2) of 1.2-1.3 Ga are consistent, indicating that Neoproterozoic crustal rocks of the Shuangqiaoshan Group could have contributed to form the Yangchuling magmas. Considering the two groups of parallel Late Mesozoic ore belts, namely the Jiangnan porphyry-skarn tungsten belt (JNB) in the south and the Middle-Lower Yangtze River porphyry-skarn Cu-Au-Mo-Fe ore belt (YRB) in the north, the Nanling granite-related W-Sn ore belt (NLB) in the south, the neighboring Qin-Hang porphyry-skarn Cu-Mo-hydrothermal Pb-Zn-Ag ore belt (QHB

  2. Paleoproterozoic pyrobitumen: Re-Os goechemistry reveals the fate of giant carbon accumulations in Russian Karelia

    Science.gov (United States)

    Hannah, J. L.; Stein, H. J.; Yang, G.; Zimmerman, A.

    2010-12-01

    Carbon-rich pyrobitumen is exposed in abundance in the Onega Basin of Karelia, northwestern Russia - the fossil remains of a giant oil field [1]. The pyrobitumen, locally termed “shungite”, occurs as veins, lenses, and droplets within the Zaonezhskaya and Kondopozhskaya Formations, part of a Paleoproterozoic platform sequence developed on a rifted continental margin. In its purest form, this material approaches 100% C. Less pure pyrobitumen occurs in Corg-rich siltstones, which are intercalated with basaltic flows and sills, including peperites. Locally, the pyrobitumen forms a massive organo-siliceous diapir, cross-cutting the sedimentary section. A Re-Os isochron for six samples of Corg-rich siltstone taken from a mine adit in Shunga village yields a precise age of 2.05 Ga [2], fitting existing constraints for the depositional age. The initial 187Os/188Os ratio given by the isochron for the Shunga adit samples is within uncertainty of chondritic (0.113 at 2.05 Ga), as expected in a restricted rift basin dominated by hydrothermal Os. Re-Os data for samples from ICDP FAR-DEEP drillhole 13A near Shunga village, tell the rest of the story. Eleven ~500 mg samples, drilled from two 3-cm intervals 0.5 m apart in a single core, yield an isochron age of ~1.73 Ga with initial 187Os/188Os = 5. This age is consistent with the latest phase of the Svecofennian orogeny [3], known to have impacted the Onega Basin. Assuming isotopic homogenization (maturation) of the pyrobitumen took place during a relatively brief thermal maximum, the largest control on the present-day 187Os/188Os is the 187Re/188Os. The 187Re/188Os for the 17 siltstone samples analyzed to date range from 280 to 1250. An average 187Re/188Os of 900 will raise the 187Os/188Os from 0.113 to about 5 during the 320 m.y. between deposition (2.05 Ga) and maturation (1.73 Ga) - precisely the value determined by our isochron. Similarly, the lower 187Re/188Os of 280 for three samples of lustrous pyrobitumen from the

  3. Re-Os dating of molybdenite from Tongchanggou Mo-polymetallic deposit in northwest Yunnan and its metallogenic environment%滇西北铜厂沟钼多金属矿床辉钼矿Re-Os同位素年龄及其成矿环境

    Institute of Scientific and Technical Information of China (English)

    李文昌; 余海军; 尹光侯; 曹晓民; 黄定柱; 董涛

    2012-01-01

    铜厂沟钼多金属矿床位于扬子陆块西缘坳陷带与义敦岛弧和甘孜-理塘结合带3个构造单元交汇部位,它是近年来对该区燕山期成矿作用研究并取得找矿突破的重要成果.该矿床包含了岩枝全岩矿化、顶部矽卡岩型及围岩热液脉型等热液交代矿化,构成了斑岩成矿系列.矿床已达大型,并显示出超大型的远景.运用辉钼矿Re-Os同位素定年技术,获得了6件样品的模式年龄,为(82.34±1.28)~(88.27±1.23) Ma,其加权平均年龄为(85±2) Ma,等时线年龄为(85±10) Ma,两者在误差范围内一致,表明成矿作用发生于燕山期,此时,该区处于中咱地块与扬子陆块强烈碰撞至后碰撞阶段,由于地壳加厚,壳熔或壳幔混熔形成了S型花岗(斑)岩和强烈的钼多金属矿化.铜厂沟矿床内辉钼矿样晶的w(Re)为16 440~43 530 ng/g,指示其成矿物质来源为壳幔混源,以壳源物质为主.据野外调查和室内研究推测,在该矿区的深部存在燕山期的隐伏花岗(斑)岩体,成矿作用与岩浆上侵有关.该区的燕山期酸性岩带穿过了义敦岛弧进入扬子陆块西缘,呈近NS向展布,滇西北地区,北部从休瓦促向南至热林、红山、铜厂沟,形成了一系列大-中型钼多金属矿床.成矿背景和成矿预测研究对该带的找矿勘查具有十分重要的指导意义.%The Tongchanggou Mo-polymetallic deposit lies in the western margin depression belt of the Yangtze land-mass and is adjacent to Yidun island arc and Garze-Litang suture zone. It is a representative ore deposit in studying Yanshanian mineralization and shows bright future for further prospecting. Some intrusions (or apophyses) have been wholly mineralized, and hydrothermal metasomatism in the upper part mainly displays skarn type and hydrothermal vein type mineralization in wall rocks, forming a porphyry minerogenetic series. The ore deposit is a large-size or even a superlarge deposit. Re-Os isotopic dating

  4. Genesis of the Au-Bi-Cu-As, Cu-Mo ± W, and base-metal Au-Ag mineralization at the Mountain Freegold (Yukon, Canada): constraints from Ar-Ar and Re-Os geochronology and Pb and stable isotope compositions

    Science.gov (United States)

    Bineli Betsi, Thierry; Lentz, David; Chiaradia, Massimo; Kyser, Kurt; Creaser, Robert A.

    2013-12-01

    The genesis of mineralized systems across the Mountain Freegold area, in the Dawson Range Cu-Au ± Mo Belt of the Tintina Au province was constrained using Pb and stable isotope compositions and Ar-Ar and Re-Os geochronology. Pb isotope compositions of sulfides span a wide compositional range (206Pb/204Pb, 18.669-19.861; 208Pb/204Pb, 38.400-39.238) that overlaps the compositions of the spatially associated igneous rocks, thus indicating a magmatic origin for Pb and probably the other metals. Sulfur isotopic compositions of sulfide minerals are broadly similar and their δ34S (Vienna-Canyon Diablo Troilite (V-CDT)) values range from -1.4 to 3.6 ‰ consistent with the magmatic range, with the exception of stibnite from a Au-Sb-quartz vein, which has δ34S values between -8.1 and -3.1 ‰. The δ34S values of sulfates coexisting with sulfide are between 11.2 and 14.2 ‰; whereas, those from the weathering zone range from 3.7 to 4.3 ‰, indicating supergene sulfates derived from oxidation of hypogene sulfides. The δ13C (Vienna Peedee Belemnite (VPDB)) values of carbonate range from -4.9 to 1.1 ‰ and are higher than magmatic values. The δ18O (V-SMOW) values of magmatic quartz phenocrysts and magmatic least-altered rocks vary between 6.2 and 10.1 ‰ and between 5.0 and 10.1 ‰, respectively, whereas altered magmatic rocks and hydrothermal minerals (quartz and magnetite) are relatively 18O-depleted (4.2 to 7.9 ‰ and -6.3 to 1.5 ‰, respectively). Hydrogen isotope compositions of both least-altered and altered igneous rock samples are D-depleted (from -133 to -161 ‰ Vienna-Standard Mean Ocean Water (V-SMOW)), consistent with differential magma degassing and/or post-crystallization exchange between the rocks and meteoric ground water. Zircon from a chlorite-altered dike has a U-Pb crystallization age of 108.7 ± 0.4 Ma; whereas, the same sample yielded a whole-rock Ar-Ar plateau age of 76.25 ± 0.53 Ma. Likewise, molybdenite Re-Os model ages range from 75.8 to

  5. Definition of petroleum generating time for Lower Cambrian bitumen of the Kuangshanliang in the west Sichuan Basin,China:Evidence from Re-Os isotopic isochron age%川西矿山梁下寒武统沥青脉油气生成时间的厘定--来自于固体沥青Re-Os同位素等时线年龄的证据

    Institute of Scientific and Technical Information of China (English)

    王杰; 腾格尔; 刘文汇; 马亮帮; 陶成; 周圆圆; 王萍; 李超

    2016-01-01

    Bitumen veins an d oil seepages,especially Lower Cambrian bitumen veins,were widely distributed in the north part of Longmenshan Mountain in western Sichuan Basin,which indicates that the prospect for Sinian and Cambrian oil reservoir is fine in the area.Although some progress has been made in the origin of bitumen veins in Lower Cambrian,there are still big differences in the source rocks.At the same time,pe-troleum producing time of bitumen vein is lack of systematically researches.Rhenium(Re)-Osmium(Os)i-sotopic chronology is a new method to apply for geochronology of hydrocarbon accumulation,and can di-rectly date the age of source rock,oil,oil sand and bitumen.The pre-treatment means and experimental in-strument on extraction and dissolution of asphaltenes,purification,enrichment and separation of Re and Os were established by a series conditional tests.Re-Os isotopic chronology consists of sample preparation,dis-solution,Re and Os purification and chemical separation,Re and Os isotope mass spectrometry measure-ments,and data treatment of by Isoplot software.The research for Re-Os isotopic isochron age and source rock of bitumen indicates that the asphalt maturity is low,the generating time of predecessor hydrocarbon is between 572Ma and 559Ma of Late Sinian in Neoproterozoic era,and it came from the very old source rocks in the Lower Cambrian in the Kuangshanliang structure.By means of Re-Os isochron ages,initial 187 Os/188 Os ratios,carbon isotope compositions and biomarkers,the Lower Cambrian bitumen in Guan-gyuan area is originated from the fine source rocks of the Doushantuo Formation in Sinian,and the hydro-carbon source rocks were of low maturity and generated a certain amount of thick oil from 572Ma to 559Ma.Subsequently,thick oil entered the Dengying layer and formed paleo-oil reservoir.Because of the late.%川西龙门山北段沥青脉与油苗广泛分布,尤其是下寒武统沥青脉,说明在龙门山褶皱带北段东缘具有寻找震旦

  6. Neoproterozic Re-Os age of a sulfide inclusion in a superdeep diamond: Implications for mantle convection beneath Juina, Brazil

    Science.gov (United States)

    Shirey, S. B.; Smit, K.; Nestola, F.; Steele, A.; Bulanova, G.; Smith, C. B.

    2015-12-01

    Diamonds from the Juina area Brazil have long been known for their sublithospheric or superdeep (e.g. from depths of 300-800 km) origins. These diamonds have yielded new information about high pressure mantle mineralogy, deep crustal recycling, diamond source fluids, and mantle transition zone water content. A type II (low N) diamond (sample J1) from the 93.1±1.5 myr old (Heaman 7IKC 1998 ) Collier 4 kimberlite was studied previously (Walter et al. Nature 2008; Bulanova et al. CMP 2010) as part of a larger suite of eclogitic-composition, inclusion-bearing type II Collier 4 diamonds with complex internal growth structure. Major and trace element analyses of mineral inclusions in these diamonds include Ca-Ti-Si perovskite, Ca-rich majoritic-garnet, clinopyroxene, olivine, jeffbenite, minerals with stoichiometries of CAS and K-hollandite phases, SiO2, FeO, native iron, low-Ni sulfides, and Ca-Mg-carbonate. The C isotopic compositions of the diamond hosts range from a δ13C of -25 to -5‰ ( J1 being -15‰). Collier 4 diamonds have been interpreted to crystallize from carbonatitic melts derived from the recycling of oceanic lithosphere at TransitionZone depths (Walter et al. Nature 2008; Bulanova et al. CMP 2010). A rare Fe-sulfide inclusion in the core of diamond J1 has been dated with the Re-Os system in order to provide age and compositional constraints on the proposed oceanic slab recycling. The rim of J1 contained inclusions of Ca-Ti-Si perovskite that yielded U-Pb age of 101±7 Ma and eclogitic (low Cr, high Ca) majorite that yielded formation pressures (Si - Al+Cr geobarometry) >8 GPa (Bulanova et al. CMP 2010). The Fe-sulfide analyzed was low Ni pyrrhotite determined to be Fe10S11 of a rare 11T polytype by single-crystal X-ray diffraction. The 27 ug interior pyrrhotite had a high Re/Os (187Re/188Os = 854) typical of MORB (Re/Os ~100) and radiogenic Os isotopic composition (187Os/188Os = 8.50±1.38) that yields a 602±16 Ma model age relative to normal mantle

  7. Palynology, geochemistry and Re-Os age of the Lower-Middle Pennsylvanian stage boundary, central Appalachian basin, USA

    Science.gov (United States)

    Geboy, N.; Tripathy, G. R.; Ruppert, L. F.; Eble, C. F.; Blake, B. M.; Hannah, J. L.; Stein, H. J.

    2014-12-01

    The central Appalachian basin (CAB) in the eastern United States contains complicated sedimentary sequences often with thin and discontinuous strata. As an economically important coal-producing region, the basin's architectural framework and depositional history are important to understand. Typically, eustatic marine incursions, marked with black shale deposits, are used for basin-wide correlation. The Betsie Shale Member of the Kanawha Formation represents one of these relatively thick and laterally extensive marine zones. This study examines the palynoflora of the Matewan coalbed, which conformably underlies the Betsie, in the context of a new Re-Os date for the Betsie Shale Member and additional geochemical measures. At its base, the Matewan contains abundant lycopsid tree spores, indicative of a submerged, flooded paleomire. Upsection, biodiversity increases to include small fern and calamite spores as well as cordaite pollen. Combined with an observed increase of inertinite, the diversification of palynoflora suggests surficial peat exposure and drying out of the paleomire. A S-rich (28 wt. %) shaley parting separates these lower and upper benches of the Matewan and may represent an initial marine pulse prior to the glacioeustatic incursion that ultimately flooded the Matewan and deposited the overlying Betsie Shale. The Betsie is organic-rich (3.05 - 4.89 wt. % TOC) with Re and Os content ranging from 320 - 1,200 ppb and 1.5 - 5.3 ppb, respectively. The highly enriched Re values result in notably high parent:daughter ratios (187Re/188Os = 3,644 - 5,737). The Re-Os isotopic data yield a Model 1 age of 323 ± 7.8 Ma (n = 7; MSWD = 0.63) with evidence that the true age lies closer to the younger end of the uncertainty. This age is consistent with previous paleontologic-based interpretations but represents the first directly measured radiometric date for the Betsie. An absolute age for the Betsie is a critical result, as the member is correlated with units in

  8. 内蒙古苏尼特右旗毕力赫大型斑岩型金矿床辉钼矿Re-Os同位素年龄及其地质意义%Molybdnite Re-Os isotope age of Bilihe large-size porphyry gold deposit in Sunid Right Banner of Inner Mongolia and its geological significance

    Institute of Scientific and Technical Information of China (English)

    卿敏; 葛良胜; 唐明国; 屈文俊; 袁士松; 赵玉锁

    2011-01-01

    between hypo-volcanic complex body and overlying volcanic rocks as well as volcanic clastic rocks, especially in the inner-contact zone. It is the first time that a large-sized porphyry gold deposit was found in the northern margin of North China plate, i.e., the Bilihe large-size porphyry gold deposit in Sunid Right Banner of Inner Mongolia. In order to identify the porphyry gold (copper) metallogenic age, the authors used Re-Os isotope to test 6 molybdnite samples collected from the porphyry, which yielded the isochron age of (272.7 ± 1.6) Ma (MSWD = 0.57). Redefinition of the late Paleozoic ore-forming geological event of the Bilihe gold deposit has provided new evidence for the convergent plate structural system in the northern part of North China in late Paleozoic, recognized some basic geological problems of the northern part of North China, and given enlightenments in search for low temperature shallow-seated porphyry gold-polymetallic deposits in the magmatic arc environment of the middle-east segments of the Central Asian Orogenic Belt in late Paleozoic.

  9. Geochemistry: how well can Pb isotopes date core formation?

    Science.gov (United States)

    Kamber, Balz S; Kramers, Jan D

    2006-11-02

    Timescale and the physics of planetary core formation are essential constraints for models of Earth's accretion and early differentiation. Wood and Halliday use the apparent mismatch in core-formation dates determined from tungsten (W) and lead (Pb) chrono-meters to argue for a two-stage core formation, involving an early phase of metal segregation followed by a protracted episode of sulphide melt addition. However, we show here that crust-;mantle Pb isotope systematics do not require diachronous core formation. Our observations indicate that very early (< or = 35 Myr) core formation and planet accretion remain the most plausible scenario.

  10. SHRIMP Zircon U-Pb and Molybdenite Re-Os Dating of the Skarn-type Tungsten Deposits in Southern Jiangxi Province, China, and Geological Implications: Examplified by the Jiaoli and Baoshan Tungsten Polymetallic Deposits%赣南矽卡岩型钨矿成岩成矿年代学及地质意义——以焦里和宝山矿床为例

    Institute of Scientific and Technical Information of China (English)

    丰成友; 曾载淋; 王松; 梁景时; 丁明

    2012-01-01

    Skarn-type tungsten deposit is a very important type of tungsten mineral resources in southern Jiangxi province.Based on detailed field investigation and analysis on major elements,trace elements,rare earth elements and radiometric dating,the ages of tungsten mineralization and petrogenesis of ore-bearing granitoids,and tectonic environment of the skarn-type tungsten deposits in southern Jiangxi province were studied.SHRIMP zircon U-Pb age for the medium to fine-gained porphyritic granodiorite from the Jiaoli ore district is 164.4 ±1.1 Ma.Molybdenite Re-Os isochron age for the related Jiaoli skarn tungsten deposit is 170.6 ±4.6 Ma.The SHRIMP zircon U-Pb age of the Baoshan medium to fine-grained granite is 156.6 ±3.9 Ma,whereas the molybdenite Re-Os mean model age for the related Baoshan skarn-type tungsten deposit is 161.0 ±1.9 Ma.Thus,W-Sn mineralization and granite crystallization taking place in Middle to Late Jurassic were contemporaneous.These new ages,combined with those available in the literature,indicate that the ages of the granites and related W-Sn ores are Middle to Late Jurassic with a peak at 150 to 160 Ma.It can be concluded that tungsten mineralization occurred under Jurassic intraplate extensional environment which was a phase of lithospheric thinning in southern China.%矽卡岩型钨矿是赣南地区的一种重要钨矿床类型.本文以焦里和宝山两个典型的矽卡岩型钨多金属矿床为例,开展了系统的成岩成矿年代学和岩石地球化学研究,结合区域钨锡矿床最新年代学研究成果,探讨了赣南地区钨矿的成岩成矿时代及形成构造环境.结果表明,焦里矽卡岩型钨多金属矿区斑状花岗闪长岩SHRIMP锆石U-Pb年龄为164.4±1.1 Ma,辉钼矿Re-Os等时线年龄为170.6 ±4.6 Ma;宝山矽卡岩型钨矿区花岗岩SHRIMP锆石U-Pb年龄为156.6±3.9 Ma,辉钼矿Re-Os模式年龄加权平均值为161.0±1.9 Ma,厘定了它们的成岩成矿年龄为中-晚侏罗世,同一矿

  11. Os isotopes in SNC meteorites and their implications to the early evolution of Mars and Earth

    Science.gov (United States)

    Jagoutz, E.; Luck, J. M.; Othman, D. Ben; Wanke, H.

    1993-01-01

    A new development on the measurement of the Os isotopic composition by mass spectrometry using negative ions opened a new field of applications. The Re-Os systematic provides time information on the differentiation of the nobel metals. The nobel metals are strongly partitioned into metal and sulphide phases, but also the generation of silicate melts might fractionate the Re-Os system. Compared to the other isotopic systems which are mainly dating the fractionation of the alkalis and alkali-earth elements, the Re-Os system is expected to disclose entirely new information about the geochemistry. Especially the differentiation and early evolution of the planets such as the formation of the core will be elucidated with this method.

  12. The 982 Ma Re-Os age of copper-nickel sulfide ores in the Baotan area, Guangxi and its geological significance

    Institute of Scientific and Technical Information of China (English)

    毛景文; 杜安道

    2002-01-01

    Re-Os dating on copper-nickel sulfide ores from the Baotan area, Guangxi, yielded an ore-forming age of 982±21 Ma(2σ), which demonstrates that copper-nickel sulfide deposits and their related mafic-ultramafic rocks occurred in the same period of time with the ophiolites in northeastern Jiangxi. Both of them are the products of collision-convergence between the Cathaysian plate and Yangtze plate and the subsequent extensional environment. Calculation of the γOs of the 982 Ma copper-nickel sulfide ores and its correlation with Re/Os indicate that injection-type massive ores display lower γOs values(-15.6 to -8.2) and lower Re/Os ratios(0.32 to 0.43), while basal liquation-type ores have γOs= -27.9 to -7.3 and Re/Os=5.36 to 11.24. This suggests that these copper-nickel sulfide ores and their related mafic-ultramafic rocks were derived from a Re-depleted mantle source and that contamination with some crustal material occurred during their intrusion.

  13. Evaluating Re-Os systematics in organic-rich sedimentary rocks in response to petroleum generation using hydrous pyrolysis experiments

    Science.gov (United States)

    Rooney, Alan D.; Selby, David; Lewan, Michael D.; Lillis, Paul G.; Houzay, Jean-Pierre

    2012-01-01

    Successful application of the 187Re-187Os geochronometer has enabled the determination of accurate and precise depositional ages for organic-rich sedimentary rocks (ORS) as well as establishing timing constraints of petroleum generation. However, we do not fully understand the systematics and transfer behaviour of Re and Os between ORS and petroleum products (e.g., bitumen and oil). To more fully understand the behaviour of Re-Os systematics in both source rocks and petroleum products we apply hydrous pyrolysis to two immature hydrocarbon source rocks: the Permian Phosphoria Formation (TOC = 17.4%; Type II-S kerogen) and the Jurassic Staffin Formation (TOC = 2.5%; Type III kerogen). The laboratory-based hydrous pyrolysis experiments were carried out for 72 h at 250, 300, 325 and 350 °C. These experiments provided us with whole rock, extracted rock and bitumen and in some cases expelled oil and asphaltene for evaluation of Re-Os isotopic and elemental abundance. The data from these experiments demonstrate that the majority (>95%) of Re and Os are housed within extracted rock and that thermal maturation does not result in significant transfer of Re or Os from the extracted rock into organic phases. Based on existing thermodynamic data our findings suggest that organic chelating sites have a greater affinity for the quadravalent states of Re and Os than sulphides. Across the temperature range of the hydrous pyrolysis experiments both whole rock and extracted rock 187Re/188Os ratios show small variations (3.3% and 4.7%, for Staffin, respectively and 6.3% and 4.9% for Phosphoria, respectively). Similarly, the 187Os/188Os ratios show only minor variations for the Staffin and Phosphoria whole rock and extracted rock samples (0.6% and 1.4% and 1.3% and 2.2%). These isotopic data strongly suggest that crude oil generation through hydrous pyrolysis experiments does not disturb the Re-Os systematics in ORS as supported by various studies on natural systems. The elemental

  14. Isotopic analyses of food crusts on pottery: Implications for dating and palaeocuisine reconstructions

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2015-01-01

    The concentrations of the stable carbon and nitrogen isotopes, δ13C and δ15N, can be used to roughly reconstruct the former content of Stone Age cooking vessels. This was supported by measurements on experimental food crusts. The reconstruction of the ingredients used in the vessels is not only...... relevant for reconstructing the diet, but also important for 14C-dating. Resources from sea- or freshwater can cause substantial radiocarbon reservoir effects. For a reliable 14C-dating, they therefore have to be identified. This study presents 14C-datings of the earliest pottery of Schleswig...

  15. Geochemical characteristics of platinum group elements and Re-Os isotopes of the Hongshishan Cu-Ni sulfide-bearing mafic-ultramafic intrusion in Beishan block of Xinjiang and their metallogenic significance%新疆北山红石山含铜镍镁铁-超镁铁质岩体PGE和Re-Os同位素地球化学特征及成矿意义

    Institute of Scientific and Technical Information of China (English)

    夏芳; 柴凤梅; 陈斌; 卢鸿飞; 严玉圃

    2012-01-01

    The Pobei mafic-ultramafic belt is an impotant Ni-Cu sulfide metallogenic prospective province in Beis-han area, eastern Xinjiang. About 20 intrusions (e.g. , Bijiashan, Hongshishan, Cihai, Poyi, Poshi and Lu-odong) were recognized along the fault in this area and almost all the intrusions are associated with Ni-Cu sulf ide deposits. The Hongshishan mafic-ultramafic complexs are located in the eastern part of the Pobei mafic-ultramafic belt and the southern part of the Baidiwa-Yunihe fault in this area. They intruded into quartz schist of the Lower Carboniferous Hongliuhe Formation. They are mainly composed of dunite, peridotite, troctolite, pyrox-enite, olivine gabbro, gabbro and diorite. These rocks were emplaced in two stages. The first stage consists ofperidotite and olivine gabbro, and the second stage comprises gabbro and diorite. The dunite, pyroxene peri-dotite and troctolite are the host rocks for Ni-Cu sulfide ores. The platinum-group elements and Re-Os isotopic compositions of ore and rocks from the Hongshishan Ni-Cu sulfide-bearing mafic-ultramafic intrusions were analyzed, and the result shows that the total PGE content is quite low, ranging from 0.54×l0~9to 15.84×1CT9 and increasing with the increase of sulfide content. The PGE primitive mantle-normalized patterns display a positive slope and low fractionation between IPGE and PPGE. PGE, Cu and Ni are depleted relative to the primitive mantle with low and a narrow Pd/Ir range (3.19 - 10.5), indicating a weak influence of later hydrothermal alteration. Furthermore, the Ir displays positive correlations with Pt, Pd, Os, Ru and Rh, indicating a weak contribution of the fractionation and the partial melt to PGE depletion. The Cu/Pd ratios(73 × 103 ~ 1 670 × 103)and Ti/Pd ratios (87 × 103~2 857 × 103)of these rocks suggest that sulfur in the primary magmas had reached saturation, and immiscible sulfides droplets were segregated from silicate magmas before their emplacement The relationship between Ni

  16. Hf isotopic compositions of the standard zircons for U-Pb dating

    Institute of Scientific and Technical Information of China (English)

    XU Ping; WU Fuyuan; XIE Liewen; YANG Yueheng

    2004-01-01

    Using the newly published Yb isotopic abundances and the mass bias relationship between Yb and Hf, we carried out an analysis of Hf isotopes in the standard zircon 91500 by means of 193 nm laser attached to Neptune multi-collector ICP-MS (LA-MC-ICPMS). The obtained Hf isotopic data, in either in situ or line scan modes, are not only identical for different spot sizes, but also are consistent with previously published results obtained on TIMS or other MC-ICPMS machines within errors. This indicates that it is possible to obtain reliable 176Hf/177Hf isotopic ratios for zircon in either in situ or line scan conditions on LA-MC-ICPMS machine, and the applied procedures in our study for elemental interfering correction are appropriate for the purpose of acquiring satisfactory accuracy for Hf isotope analyses. The Hf isotopic compositions of four zircon standards in high spatial resolution U-Pb dating, 91500, CZ3,CN92-1 and TEMORA, are measured, respectively. The obtained 176Hf/177Hf ratios are 0.282316+4 (n = 34, 2σ) for 91500, 0.281704±6 (n = 16, 2σ) for CZ3, 0.282200±6 (n = 20,2σ-) for CN92-1 and 0.282684±14 (n = 24, 2σ) for TEMORA,respectively, with 176Lu/177Hf ratios of ~0.00031, 0.000036,0.00083 and 0.00127. Zircons 91500 and CZ3 show narrower variations in 176Hf/177Hf and 176Lu/177Hf ratios than those of zircons CN92-1 and TEMORA, and thus are appropriate standards for the Hf isotope analysis.

  17. Radium isotopes in groundwater around Fuji Volcano, Japan -application for groundwater dating on volcanic area-

    Science.gov (United States)

    Ohta, T.; Mahara, Y.

    2010-12-01

    Young groundwater dating less than 100 years is possible to be obtained from environmental radioactivity with short half life, 3H+3He, 85Kr, or chemical material, CFC-12. The 3H+3He dating method is excellent method to estimate the residence time of shallow groundwater. The one of advantage of the method is small sample volume. The 3He in groundwater is originated by 3 sources, tritiogenic He, mantle He, radiogenic He produced in rock. Especially, as the contribution of the mantle He is greater than the radiogenic and triogenic, when 3H+3He dating apply for groundwater dating on volcanic area, we have to determine ratio of 3 sources. On the other hand, as 85Kr is only originated from atmosphere, it is excellent groundwater dating tracer on volcanic area. However, as 85Kr is ultra low concentration in groundwater, 85Kr is needed to separate from large amount of ground water about 10^5 L. Young groundwater dating by these methods has both advantages and disadvantages, but the disadvantages of the individual methods can be offset by using multiple tracers. Development of a lot of groundwater dating techniques is desired. Therefore, an application of radium isotopes which is simple origin to groundwater dating on volcanic area was tried. Ra-228 and Ra-226 are progenies of Th and U, respectively. The 228Ra/226Ra in ground waters depends on the Th/U in the relevant rocks. As the 228Ra and 226Ra in shallow groundwater on volcanic area are originated from only rock, and the collection of radium isotopes from groundwater is easier than that of 85Kr, implying that it is possible to be good tracer for volcanic area. We aim that groundwater age obtain from 228Ra/226Ra in groundwater and relevant rock on volcanic area. We determined that 228Ra/226Ra observed with river waters and the relevant rocks. The method applied for Kakitagawa around Fuji Volcano, Japan. The relevant rock of Kakitagawa is Mishima lava flow. Our method compared with 3H+3He dating. The residence time of

  18. Re-Os geochronology of the El Salvador porphyry Cu-Mo deposit, Chile: Tracking analytical improvements in accuracy and precision over the past decade

    Science.gov (United States)

    Zimmerman, Aaron; Stein, Holly J.; Morgan, John W.; Markey, Richard J.; Watanabe, Yasushi

    2014-04-01

    Sulfide minerals from the El Salvador porphyry Cu-Mo deposit, Chile, were dated by Re-Os geochronology to clarify the timing and duration of mineralization. As these data are collected over the past 10 years, they chronicle the evolution of Re-Os analytical procedures and improvements in spike-sample equilibration, mass spectrometry and data reduction. Included in the data is the first tennantite-pyrite Re-Os isochron along with tennantite-enargite-pyrite Os tracing of ore metals based on initial osmium systematics (187Os/188Osi). Porphyry-associated mineralization follows the traditional early (A), transitional (B), and late (D) stage classification of relative timing of vein formation. Most Cu- and Mo-bearing sulfides were deposited during stages A and B. Field relationships clearly show the B-stage veins are older than the D-stage veins. Samples analyzed with Carius tube digestion and mixed-double spike indicate B-stage molybdenite mineralization between 41.8 and 41.2 Ma. These ages best represent the timing of main-stage mineralization at El Salvador. A five-point 187Re-187Os isochron for pyrite-tennantite from the latest D-stage veins yields an age of 42.37 ± 0.45 Ma. The isochron age, while older, is within error of early analyses of molybdenite by alkaline fusion digestion using single Re and Os spikes (42.4-42.0 Ma). A separate pyrite and tennantite-enargite pair containing significant common Os yields an initial 187Os/188Os ratio of 0.134 ± 0.042, compatible with a predominantly mantle origin. We appreciate the early analyses for their historical significance while emphasize the geological implications of the 41.8-41.2 Ma molybdenite ages. Temperature estimates by sulfur thermometry and fluid inclusions are 390-510 °C for the B-stage molybdenites and 230-240 °C for the latest D-stage pyrite and tennantite. Analyses based on Carius tube digestion and updated spike calibrations suggest a ∼0.6 m.y. duration (∼41.8 to 41.2 Ma) in-line with published

  19. Isotopic Characteristics and Age Dating of the Pumice in Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    陈丽蓉; 翟世奎; 申顺喜

    1994-01-01

    The data on the isotope compositions of rubidium,strontium and oxygen in the pumice ofOkinawa Trough are reported for the first time.The ages of the pumice were successfully dated with themethod of U-series disequilibrium.Then,the material source,crystallization evolution of magma and activi-ty cycles of volcanos are explored.Isotopic data show that pumice magma was originally from the mantle,but had undergone a full crystal-lization differentiation and had been contaminated to a fair extent by crust-derived materials before the mag-ma was erupted out of the sea floor.According to the dating results available so far,the earliest volcaniceruption in Okinawa Trough occurred about 70,000 a ago and the latest eruption was about 10,000 a B.P.During this period,there were three volcanic eruption cycles which were respectively corresponding to themiddle Late Pleistocene,the late Late Pleistocene and the Early Holocene.

  20. Re-Os sulfide geochronology of the Red Dog sediment-hosted Zn-Pb-Ag deposit, Brooks Range, Alaska

    Science.gov (United States)

    Morelli, R.M.; Creaser, R.A.; Selby, D.; Kelley, K.D.; Leach, D.L.; King, A.R.

    2004-01-01

    The Red Dog sediment-hosted deposit in the De Long Mountains of northern Alaska is the largest Zn producer in the world. Main stage mineralization is characterized by massive sulfide ore and crosscutting subvertical veins. Although the vein mineralization is clearly younger than the massive ore, the exact temporal relationship between the two is unclear. Re-Os geochronology of pyrite is used to determine the absolute age of main stage ore at Red Dog. A 10-point isochron on both massive and vein pyrite yields an age of 338.3 ?? 5.8 Ma and is interpreted to represent the age of main stage ore. The Re-Os data indicate that both massive and vein ore types are coeval within the resolution of the technique. Formation of the Red Dog deposit was associated with extension along a passive continental margin, and therefore the Re-Os age of main stage ore constrains the timing of rifting as well as the age of the host sedimentary rocks. Sphalerite from both massive and vein ore yields imprecise ages and shows a high degree of scatter compared to pyrite. We suggest that the Re-Os systematics of sphalerite can be disturbed and that this mineral is not reliable for Re-Os geochronology. ?? 2004 by Economic Geology.

  1. Significance of the whole rock Re-Os ages in cryptically and modally metasomatised cratonic peridotites: Constraints from HSE-Se-Te systematics

    Science.gov (United States)

    Luguet, Ambre; Behrens, Melanie; Pearson, D. Graham; König, Stephan; Herwartz, Daniel

    2015-09-01

    The Re-Os isotopic system is the geochronometer of choice to constrain the timing of lithospheric mantle root formation and reconstruct the evolution of Earth's dynamics from the "mantle" perspective. In order to constrain the effects of metasomatic processes on the Re-Os isotopic system, eleven peridotites from the Letlhakane kimberlite pipe were investigated for whole rock major and trace elements, highly siderophile elements (HSE), Se, Te and 187Os/188Os signatures. These spinel peridotites (SP), garnet peridotites (GP), garnet-phlogopite peridotites (GPP) and phlogopite peridotites (PP) experienced cryptic metasomatism and the GP-GPP-PP additionally constitute a sequence of increasing modal metasomatism. The cryptically metasomatised SP appear devoid of base metal sulphides (BMS) and show suprachondritic Se/Te ratios (15-40) and extremely Pd- and Pt-depleted HSE patterns. These features are characteristic of high-degree partial melting residues. Their 187Os/188Os signatures are thus considered to be inherited from the partial melting event. This implies a Neoarchean (2.5-2.8 Ga, TRD eruption) stabilisation of the Letlhakane mantle root and supports the Letlhakane mantle root being a westerly extension of the Zimbabwe cratonic root. The modally metasomatised peridotites contain BMS whose abundance significantly increases from the GPP to the GP and PP. The BMS-poor GPP are only slightly richer in Pt and Pd than the BMS-free SP but have similarly high Se/Te ratios. The BMS-rich GP and PP exhibit significant enrichments in Pt, Pd, Se, Te resulting in HSE-Se-Te signatures similar to that of the Primitive Upper Mantle (PUM). Addition of 0.001-0.05 wt.% metasomatic BMS ± PGM (platinum group minerals, i.e., Pt-tellurides) to highly refractory residues, such as the Letlhakane SP, reproduce well the HSE-Se-Te systematics observed in the BMS-poor and BMS-rich modally metasomatised peridotites. In the GPP, the negligible addition of metasomatic BMS ± PGM did not disturb

  2. Dating prograde fluid pulses during subduction by in situ U-Pb and oxygen isotope analysis

    Science.gov (United States)

    Gauthiez-Putallaz, Laure; Rubatto, Daniela; Hermann, Jörg

    2016-02-01

    -system equilibrium fractionation during prograde to peak temperatures. The resulting equilibrium ∆18Ozircon-monazite at 700 ± 20 °C is 0.1 ± 0.7 ‰. The in situ oxygen isotope data argue against an externally derived input of fluids into the whiteschists. Instead, fluid-assisted zircon and monazite recrystallisation can be linked to internal dehydration reactions during prograde subduction. We propose that the major metasomatic event affecting the granite protolith was related to hydrothermal seafloor alteration post-dating Jurassic rifting, well before the onset of Alpine subduction.

  3. Re-Os systematics and age of pyrite associated with stratiform Zn-Pb mineralization in the Howards Pass district, Yukon and Northwest Territories, Canada

    Science.gov (United States)

    Kelley, Karen D.; Selby, David; Falck, Hendrik; Slack, John F.

    2016-05-01

    Stratiform Zn-Pb deposits hosted in unmetamorphosed carbonaceous and siliceous mudstones of the Ordovician to Silurian Duo Lake Formation define the Howards Pass district in Yukon Territory and Northwest Territories, western Canada. Collectively, the deposits are amongst the largest in the world, containing drill-indicated and inferred resources of 423 Mt at 4.84 % Zn and 1.59 % Pb. Sulphide textures include (a) fine-scale laminations of sphalerite, galena, and pyrite from rock; (b) layers of coarse sulphide that are structurally controlled by microfolds; and (c) veins that cut bedding and sulphide laminations. The finely interlaminated nature of sulphides with mudstone has been used as evidence for syngenetic mineralizing processes, whereas paleomagnetic data determined on coarse layered sulphides suggest a Middle Jurassic age of mineralization. Here, we present new rhenium-osmium (Re-Os) isotopic data for 12 pyrite separates obtained from 4 laminated sulphide-rich samples from the XY Central (XYC) and Don (DON) deposits and for 1 unmineralized organic-rich mudstone ˜20 m stratigraphically below the sulphide-bearing zone. Pyrite separates that lack mudstone inclusions ("pure") from the XYC deposit contain 2.2 to 4.0 ppb Re and 93.4 to 123.4 ppt Os; pure pyrite from the DON deposit is significantly more enriched in Re and Os (34-37 ppb Re; 636.8-694.9 ppt Os). The 187Re/188Os values of pure pyrite separates from the XYC and DON deposits range from 137.6 to 197 and 182.1 to 201.4, respectively. Regression of all pure pyrite Re-Os data from both deposits yields an isochron age of 442 ± 14 Ma (MSWD = 7.4) and an initial 187Os/188Os (Osi) value of 0.71 ± 0.07. The Re-Os age indicates that the early phase of pyrite precipitation (and by inference, sphalerite and galena) occurred during the early Silurian, consistent with biostratigraphic ages of the host rocks. The Osi value of ˜0.8 for earliest Silurian seawater recorded from organic-rich shale in the basal

  4. Geochemistry and Re-Os geochronology of the organic-rich sedimentary rocks in the Jingtieshan Fe-Cu deposit, North Qilian Mountains, NW China

    Science.gov (United States)

    Yang, Xiuqing; Zhang, Zuoheng; Li, Chao; Duan, Shigang; Jiang, Zongsheng

    2016-04-01

    The Jingtieshan Group in the North Qilian Mountains, NW China, is dominantly composed of banded iron formations (BIFs), copper deposits and organic-rich sedimentary rocks (ORS, carbonaceous phyllite). X-ray diffraction analysis of the ORS shows the mineral assemblage to be quartz + clay minerals. The total organic carbon contents show a range of 0.44-1.72%. Here we present the results of the geochemistry and Re-Os geochronology of the ORS from the Jingtieshan Group. The high values of Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), Plagioclase Index of Alteration (PIA), and Th/U ratio, indicate intense weathering. The Al2O3/TiO2, Zr/Sc, Th/Sc, La/Th ratios, high rare earth elements abundances, light rare earth elements enrichment (normalized to chondrite), and distinctly negative Eu anomalies, suggest that the Jingtieshan Group ORS were derived mainly from felsic volcanic units. The new Re-Os isochron age of 1308 ± 100 Ma (2σ, n = 6, MSWD = 23) broadly overlap with the previous published ages determined using Sm-Nd and U-Pb isotope systems. The new age represents the depositional age of the Jingtieshan Group, as well that of BIF in the Jingtieshan area. Furthermore, the initial 187Os/188Os ratios (0.44 ± 0.07) indicate that the Os in the seawater was dominantly derived from hydrothermal fluids (∼75%). The Ce anomaly (Ce/Ce∗ = 0.95-1.00) and V/(V + Ni) ratios (0.71-0.86), as well as the lack of enrichment in redox-sensitive trace elements such as U, V, Zn, Pb, Cu, Ni, Cr, Co and Mn, together with the presence of overlying BIF, suggest that the Jingtieshan area represents a ferruginous deep-water succession. This, and intense submarine hydrothermal activities contributed to the deposition of the Jingtieshan BIF.

  5. Ab initio study of interstitial cluster interaction with Re, Os, and Ta in W

    Science.gov (United States)

    Setyawan, Wahyu; Nandipati, Giridhar; Kurtz, Richard J.

    2017-02-01

    The stability of tungsten self-interstitial atom (SIA) clusters is studied using first-principles methods. Clusters from one to seven SIAs are systematically explored from 1264 unique configurations. Finite-size effect of the simulation cell is corrected based on the scaling of formation energy versus inverse volume cell. Furthermore, the accuracy of the calculations is improved by treating the 5p semicore states as valence states. Configurations of the three most stable clusters in each cluster size n are presented, which consist of parallel [111] dumbbells. The evolution of these clusters leading to small dislocation loops is discussed. The binding energy of size-n clusters is analyzed relative to an n → (n-1) + 1 dissociation and is shown to increase with size. Extrapolation for n > 7 is presented using a dislocation loop model. In addition, the interaction of these clusters with a substitutional Re, Os, or Ta solute is explored by replacing one of the dumbbells with the solute. Re and Os strongly attract these clusters, but Ta strongly repels. The strongest interaction is found when the solute is located on the periphery of the cluster rather than in the middle. The magnitude of this interaction decreases with cluster size. Empirical fits to describe the trend of the solute binding energy are presented.

  6. Initial and Diagenetic Behaviour of U Isotopes in Corals: Implications for U-series Dating

    Science.gov (United States)

    Robinson, L. F.; Adkins, J. F.; Fernandez, D.; Burnett, D.; Gagnon, A.; Krakauer, N.; Wang, S.

    2005-12-01

    U-series isotopes in corals are one of the most powerful tools for chronometry in Quaternary Paleoceanography. Modern mass spectrometric techniques routinely reach 1 permil precision for the isotopic ratios of uranium and thorium. However, the corals themselves are often found to be open systems for U-series dating. The most widely used metric for diagenetic alteration of the age is the deviation of the δ234U ratio from the seawater value of 146‰. In this study we use deep-sea corals that live and are preserved in a constant seawater environment to investigate the causes of this diagenetic alteration. Coral thin-sections display complex visible banding patterns based on the crystal morphology. Fission track maps and MC-ICP-MS measurements performed on micro-milled sub-samples reveal a primary [U]-variability that has a spatial distribution closely related to the visible banding. Sub-samples from fossil corals, ranging in age from 11 ka to 218 ka, have variable δ234Uinitial with the highest δ234Uinitial values in areas of low [U]. A model shows that most of the variability can be explained by two simple processes, direct transfer of alpha recoil 230Th and 234Th and, more importantly, preferential movement of alpha-decay mobilised 234U. Coupling this preferential movement with a high [U] coating such as an organic film provides a source of 234U to the coral lattice that can account for large δ234Uinitial elevations, with little change to the final age. As surface corals also have large initial [U] gradients, our results demonstrate that many elevated δ234Uinitial values are a natural consequence of the coral's initial [U] gradient. These gradients are biologically induced at the time of calcification and are an example of how better understanding the effects of biomineralization can improve our interpretation of paleotracers.

  7. 内蒙古额勒根斑岩型钼(铜)矿化区辉钼矿铼-锇同位素年龄及地质意义%Re-Os isotopic age dating of molybdenite separates from Elegen porphyry Mo (Cu)mineralized area, northwestern Alxa, western Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    聂凤军; 屈文俊; 刘妍; 杜安道; 江思宏

    2005-01-01

    为了查明额勒根矿化区斑岩型钼(铜)矿化发生的时间,对主要矿化体内5件辉钼矿样品进行了铼-锇同位素分析,所获同位素等时线年龄为(332.0±9.0)Ma(2σ),其MSWD值为0.29.鉴于辉钼矿呈浸染状分布于似斑状花岗闪长岩和花岗闪长斑岩体中,并且与黄铜矿和黄铁矿呈共生结构关系,推测额勒根地区斑岩型钼(铜)矿化体、似斑状花岗闪长岩和花岗闪长斑岩体的形成时间为早石炭世中期,均是海西中期构造-岩浆活动的产物.

  8. Guided ion beam and theoretical studies of the reactions of Re+, Os+, and Ir+ with CO

    Science.gov (United States)

    Kim, JungSoo; Cox, Richard M.; Armentrout, P. B.

    2016-11-01

    The kinetic-energy dependences of the reactions M+ + CO where M+ = Re+, Os+, and Ir+ are studied using guided ion-beam tandem mass spectrometry. Formation of both MO+ and MC+ was observed in endothermic processes for all three metals. Modeling of the data provides thresholds that yield 0 K bond dissociation energies (BDEs, in eV) of 4.67 ± 0.09 (Re+-O), 4.82 ± 0.14 (Os+-O), 4.25 ± 0.11 (Ir+-O), 5.13 ± 0.12 (Re+-C), 6.14 ± 0.14 (Os+-C), and 6.58 ± 0.12 (Ir+-C). These BDEs agree well with literature values within experimental uncertainties demonstrating that ground state products are formed for all cases even though some of the reactions are formally spin forbidden. Quantum mechanical calculations at several levels of theory and using several basis sets were performed for MC+ and MO+ (with comparable results taken from the literature in some cases). B3LYP and CCSD(T) calculated ground state BDEs agree reasonably well with experimental values. The ground states in B3LYP and CCSD(T)/CBS calculations are -3Σ (ReC+), 2Δ (OsC+), and +1Σ or 3Δ (IrC+) after including spin-orbit considerations. Relaxed potential energy surfaces (PESs) for the M+ + CO reactions show crossings between surfaces of different spin states such that products can be formed with no barriers in excess of the substantial endothermicities. Unlike results for these metal cations reacting with O2, the kinetic energy dependent cross sections for the formation of MO+ in the M+ + CO reactions exhibit only one feature. Reasons for this differential behavior are discussed in detail.

  9. New evaluation of alpha decay half-life of {sup 190}Pt isotope for the Pt-Os dating system

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, O.A.P.; Medeiros, E.L. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Terranova, M.L. [Universita degli Studi di Roma Tor Vergata (Italy). Dipt. di Scienze e Tecnologie Chimiche; Istituto Nazionale di Fisica Nucleare (INFN), Rome (Italy)

    2005-08-15

    A semiempirical model based on the quantum mechanical tunnelling mechanism of alpha emission from nuclei has been used to evaluate the half-life of the Pt isotopes. For the important naturally occurring {sup 190}Pt isotope, the radiogenic parent in the {sup 190} Pt {yields} {sup 186}Os dating system, the model yielded a half-life value of (3.7{+-} 0.3) versus 10{sup 11} y. This is comparable to (3.2{+-}0.1) versus 10{sup 11} y which was obtained in the last direct counting experiment to measure the alpha activity of {sup 190}Pt (Tavares and Terranova, Rad. Measurem. 27 (1997) 19). A literature survey of available alpha decay half-life values for {sup 190}Pt isotope is also reported. The significant discrepancies found between data obtained by direct counting, indirect geological methods and different calculation models are analysed and discussed. (author)

  10. Re-Os pyrite geochronology of Zn-Pb mineralization in the giant Caixiashan deposit, NW China

    Science.gov (United States)

    Li, Dengfeng; Chen, Huayong; Hollings, Pete; Zhang, Li; Mi, Mei; Li, Jie; Fang, Jing; Wang, Chengming; Lu, Wanjian

    2016-03-01

    The newly discovered Caixiashan Irish-type Zn-Pb deposit (˜131 Mt at 3.95 % Zn + Pb), located in the Eastern Tianshan of Xinjiang, is one of the largest Zn-Pb deposits in NW China. Massive colloform/framboidal textured syn-sedimentary pyrite yielded a Re-Os isochron age of 1019 ± 70 Ma (MSWD = 3.5), which is interpreted to be the depositional age of the Kawabulake group that hosts the ore. The age of the main mineralization stage is constrained by two types of pyrite: the layered pyrite coexists with recrystallized calcite and dolomite and is locally replaced by sphalerite, whereas the euhedral pyrite occurs with galena that crosscuts the massive sphalerite. The layered pyrite yielded a Re-Os age of 859 ± 79 Ma (MSWD = 6.7; initial 187Os/188Os ratio [IOs] = 0.19 ± 0.25) and the euhedral pyrite 837 ± 39 Ma (MSWD = 6.5; [IOs] = 0.16 ± 0.09), which are interpreted to be the Zn and Pb mineralization ages, respectively. The low radiogenic initial Os values of the Zn-Pb mineralization suggest interaction between a hydrothermal fluid and a mafic or ultramafic source rock with a mantle Os signature with some contamination with Mesoproterozoic Kawabulake group. Based on our new Re-Os ages, we conclude that the giant Caixiashan Zn-Pb deposit formed in the early Neoproterozoic and it represents a newly identified mineralization epoch in the Eastern Tianshan of the Central Asia Orogenic Belt.

  11. Rhenium-osmium isotope constraints on the age and source of the platinum mineralization in the Lower Cambrian black rock series of Hunan-Guizhou provinces, China

    Institute of Scientific and Technical Information of China (English)

    李胜荣; 肖启云; 申俊峰; 孙丽; 刘波; 阎柏琨; 江永宏

    2003-01-01

    The shale at the bottom of the Lower Cambrian black series in South China is rich in nonferrous metals, noble metals, rare and dispersed elements and radioactive elements, known as "polyelement-rich bed". In order to date and trace the source of the platinum group elements, 6 samples were collected from the Zhongnan region of Guizhou Province, and the Ganzi- ping-Sancha region of Hunan Province. The contents and isotopes of Re and Os were measured. Re and Os are positively correlated with each other and the correlation coefficient between 187Os/188Os and 187Re/188Os is 0.99856. On the 187Os/188Os-187Re/188Os diagram, 6 sample points are well-distributed along the (542±11) Ma fitting isochron in high coincidence and with 0.84±0.12 as the initial 187Os/188Os value. The result displays that the age value of the major mineralization of Re, Os and other platinum group elements is (542±11) Ma, which is identical with the stratigraphical age of the wall rocks; the 'polyelement beds' in Hunan and Guizhou provinces bear high isochroneity; the differences of the forming times of different materials in the 'polyelement bed' of the same area do not surpass the error limit permissible for Re-Os date fitting; there exists no distinct time interval between the formation of the diagenetic veinlets and that of the 'polyelement bed', or the Re-Os isotope composition has not been distinctly changed by the former process; basaltic crust might be the major source of Re, Os, other platinum group and trace elements in the Lower Cambrian 'polyelement bed' of Hunan and Guizhou provinces.

  12. Isotopic composition analysis and age dating of uranium samples by high resolution gamma ray spectrometry

    Science.gov (United States)

    Apostol, A. I.; Pantelica, A.; Sima, O.; Fugaru, V.

    2016-09-01

    Non-destructive methods were applied to determine the isotopic composition and the time elapsed since last chemical purification of nine uranium samples. The applied methods are based on measuring gamma and X radiations of uranium samples by high resolution low energy gamma spectrometric system with planar high purity germanium detector and low background gamma spectrometric system with coaxial high purity germanium detector. The "Multigroup γ-ray Analysis Method for Uranium" (MGAU) code was used for the precise determination of samples' isotopic composition. The age of the samples was determined from the isotopic ratio 214Bi/234U. This ratio was calculated from the analyzed spectra of each uranium sample, using relative detection efficiency. Special attention is paid to the coincidence summing corrections that have to be taken into account when performing this type of analysis. In addition, an alternative approach for the age determination using full energy peak efficiencies obtained by Monte Carlo simulations with the GESPECOR code is described.

  13. Re/Os Constraint on the Time Variability of the Fine-Structure Constant

    Science.gov (United States)

    Fujii, Yasunori; Iwamoto, Akira

    2003-12-01

    We argue that the accuracy by which the isochron parameters of the decay 187Re→187Os are determined by dating iron meteorites may constrain the possible time dependence of the decay rate and hence of the fine-structure constant α, not directly but only in a model-dependent manner. From this point of view, some of the attempts to analyze the Oklo constraint and the results of the quasistellar-object absorption lines are reexamined.

  14. Re/Os constraint on the time-variability of the fine-structure constant

    CERN Document Server

    Fujii, Y; Fujii, Yasunori; Iwamoto, Akira

    2003-01-01

    We argue that the accuracy by which the isochron parameters of the decay $^{187}{\\rm Re}\\to ^{187}{\\rm Os}$ are determined by dating iron meteorites may not directly constrain the possible time-dependence of the decay rate and hence of the fine-structure constant $\\alpha$. From this point of view, some of the attempts to analyze the Oklo constraint and the results of the QSO absorption lines are re-examined.

  15. Reply to the comment by Wu et al. (2016) on "Behavior of Re and Os during contact between an aqueous solution and oil: Consequences for the application of the Re-Os geochronometer to petroleum" [Geochim. Cosmochim. Acta 158 (2015) 1-21

    Science.gov (United States)

    Reisberg, Laurie; Michels, Raymond; Mahdaoui, Fatima

    2016-08-01

    We reply here to the questions raised by Wu et al. concerning the results published by Mahdaoui et al. (2015). This paper describes experiments in which aqueous solutions containing ReO4- and OsCl62- were brought in contact with natural oils at various ranges of concentration, time and temperature. The main observation is that the transfer of Re and Os to oils is very efficient under all experimental conditions. Wu et al. argue that thermodynamic equilibrium was not achieved in these experiments as apparent partition coefficients are inconsistent. They conclude that the experiments were flawed by possible leaking of reactors and that the conclusions by Mahdaoui et al. (2015) were not justified. In the following reply we explain that Mahdaoui et al. (2015) never claimed that thermodynamic equilibrium was achieved. Any calculations or considerations in this context are therefore meaningless. We recall the objectives of our publication, which were to experimentally test the behavior of ReO4- and OsCl6- (two plausible chemical forms of Re and Os in deep aquifers of petroleum systems) in aqueous solution-oil systems. To our knowledge these are the first experiments of their kind. The parameters that could influence the precision and reproducibility of our results were discussed in detail in Mahdaoui et al. (2015). The essential point is that all 60 of the experiments provide evidence of substantial transfer of Re and Os from water to oil. In contrast to what was mistakenly understood by Wu et al., the paper does not challenge the use of Re-Os to date geological events affecting petroleum. Instead, by providing a mechanism that might allow Os isotopic homogenization on a basin-wide scale, a critical step missing from most current models, it offers a possible explanation of how Re-Os geochronology in oils could potentially work. More generally, our study suggests that transfer of Re and Os from waters to oil may be an important phenomenon that should not be overlooked.

  16. Isotopic dating of the Chengjiang Fauna-bearing horizon in Central Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Twenty black shale samples, which are free from the influence of weathering, were collected from the Chengjiang Fauna-bearing horizon, central Yunnan Province, yielding a Pb-Pb isochron age of 534±60 Ma. Although this age is younger than both the Rb-Sr isochron age and 40Ar-39Ar age, it should represent the lower isotopic age limit of the Chengjiang Fauna.

  17. Global correlation for strontium isotope curve in the Late Cretaceous of Tibet and dating marine sediments

    Institute of Scientific and Technical Information of China (English)

    HUANG; Sijing; SHI; He; SHEN; Licheng; ZHANG; Meng; WU; Wen

    2005-01-01

    87Sr/86Sr ratios of marine carbonate samples collected from a sedimentary section of the Late Cretaceous in the south of Tibet were measured. Based on the absence of cathodoluminescence and a very low Mn/Sr ratio (average 0.06) of the samples, it is thought that they contain information on the original seawater strontium isotope composition. The strontium isotope evolution curve of the Late Cretaceous in Tibet we established here, is consistent with other coeval curves from Europe, North America and Antarctica, supports the notion that the strontium isotope composition of seawater is governed by global events, which provides a new approach for the inter-continental and inter-basinal correlations of Late Cretaceous in the area and is a complementarity for biostratigraphy. In addition, we attempt to determine the age of the boundaries for Campanian/Santonian and Maastrichtian/Campanian by 87Sr/86Sr ratios for Gamba section in southern Tibet. The two boundaries are located in the thickness of 217 m (83.5 Ma) and 291 m (71.3 Ma), respectively.

  18. U-Pb, Re-Os, and 40Ar/39Ar geochronology of the Nambija Au-skarn and Pangui porphyry Cu deposits, Ecuador: implications for the Jurassic metallogenic belt of the Northern Andes

    Science.gov (United States)

    Chiaradia, Massimo; Vallance, Jean; Fontboté, Lluis; Stein, Holly; Schaltegger, Urs; Coder, Joshua; Richards, Jeremy; Villeneuve, Mike; Gendall, Ian

    2009-05-01

    New U-Pb, Re-Os, and 40Ar/39Ar dates are presented for magmatic and hydrothermal mineral phases in skarn- and porphyry-related ores from the Nambija and Pangui districts of the Subandean zone, southeastern Ecuador. Nambija has been one of the main gold-producing centers of Ecuador since the 1980s due to exceptionally high-grade ores (average 15 g/t, but frequently up to 300 g/t Au). Pangui is a recently discovered porphyry Cu-Mo district. The geology of the Subandean zone in southeastern Ecuador is dominated by the I-type, subduction-related, Jurassic Zamora batholith, which intrudes Triassic volcanosedimentary rocks. The Zamora batholith is in turn cut by porphyritic stocks, which are commonly associated with skarn formation and/or porphyry-style mineralization. High precision U-Pb and Re-Os ages for porphyritic stocks (U-Pb, zircon), associated prograde skarn (U-Pb, hydrothermal titanite), and retrograde stage skarn (Re-Os, molybdenite from veins postdating gold deposition) of the Nambija district are all indistinguishable from each other within error (145 Ma) and indicate a Late Jurassic age for the gold mineralization. Previously, gold mineralization at Nambija was considered to be Early Tertiary based on K-Ar ages obtained on various hydrothermal minerals. The new Jurassic age for the Nambija district is slightly younger than the 40Ar/39Ar and Re-Os ages for magmatic-hydrothermal minerals from the Pangui district, which range between 157 and 152 Ma. Mineralization at Nambija and Pangui is associated with porphyritic stocks that represent the last known episodes of a long-lived Jurassic arc magmatism (˜190 to 145 Ma). A Jurassic age for mineralization at Nambija and Pangui suggests that the Northern Andean Jurassic metallogenic belt, which starts in Colombia at 3° N, extends down to 5° S in Ecuador. It also adds a new mineralization style (Au-skarn) to the metal endowment of this belt.

  19. Sm-Nd isotope dating of hydrothermal calcites from the Xikuangshan antimony deposit, Central Hunan

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The research on Samarium-Neodymium isotope systematics of hydrothermal calcites from the Xikuangshan antimony deposit, Central Hunan, places precise timing constraints on the Sb mineralization in this area. It is revealed that the Xikuangshan deposit formed during the late Jurassic-early Cretaceous Period, the early- and late- stage mineralization took place at (155.5 ± 1.1) Ma and (124.1 ± 3.7) Ma, respectively. The accurate age determination of mineralization is very crucial for revealing the super-enrichment mechanism of the element Sb at the Xikuangshan mine, and lays some foundations for the further understandings of its ore genesis and mineralization mechanism.

  20. Temporal evolution of mineralization events in the Bohemian Massif inferred from the Re-Os geochronology of molybdenite

    Science.gov (United States)

    Ackerman, Lukáš; Haluzová, Eva; Creaser, Robert A.; Pašava, Jan; Veselovský, František; Breiter, Karel; Erban, Vojtěch; Drábek, Milan

    2016-10-01

    Molybdenite is a common mineral accompanying Sn-W, Au, and base metal mineralizations located in different geotectonic units of the Bohemian Massif, but it is also widespread in granitoids and/or related quartz veins/pegmatites forming disseminated Mo mineralization. Thirty Re-Os ages were obtained for molybdenite samples from the Bohemian Massif to provide constraints on the timing and duration of mineralization event(s) within the framework of previously published geochronological data for the host and/or associated rocks. The obtained data for Sn-W-(Li) deposits in the Erzgebirge metallogenetic province indicate the predominance of one and/or multiple short-time mineralization events taking place between ˜319 and 323 Ma, with the exception of the Krupka deposit associated with the Altenberg-Teplice caldera where the data may suggest prolonged activity until ˜315 Ma. The ages of the Pb-Zn-(Au-Mo) Hůrky u Rakovníka and Fe-Cu-As Obří důl mineralizations from the exocontacts of the Čistá pluton and Krkonoše-Jizera Plutonic Complex, respectively, provide evidence for synchronous emplacement of the ore and the associated granitic rocks. In contrast, the Padrť Fe-As-Mo mineralization postdates the age of the associated Padrť granite. Disseminated Mo mineralization in Cadomian and Variscan granitoids and/or related to quartz veins/pegmatites provides Re-Os ages that overlap with the previously published geochronological data for the host rocks, suggesting coeval evolution. Molybdenite samples from the Sázava suite granites of the Central Bohemian Plutonic Complex (CBPC) have resolvable younger ages than their host granites, but similar to the age of spatially related Au mineralization which is associated with the latest evolution of the CBPC.

  1. Molecular Radiocarbon Dating of Tropical Lake Sediments: Insights into the Chronology of Leaf Wax Stable Isotope Records

    Science.gov (United States)

    Douglas, P. M.; Pagani, M.; Eglinton, T. I.; Brenner, M.; Curtis, J. H.; Hodell, D. A.

    2010-12-01

    Leaf wax δD and δ13C measurements in marine and lacustrine sediment cores are promising proxies for past climatic and environmental change. However, a number of studies of marine sediments indicate centennial to millennial scale offsets between the radiocarbon ages of leaf waxes and the age of surrounding sediments due to long-term storage of these lipids in soils. These offsets present a complication for the interpretation of leaf wax stable isotope records that has not been thoroughly addressed. We present leaf wax δD, δ13C and Δ14C values for a sediment core from Lake Chichancanab in southeastern Mexico. This lake was previously studied using mineralogical (gypsum) and carbonate isotopic (δ18O) climate proxies, which indicated a sequence of severe droughts from 750 to 1000 AD, coincident with the collapse of the Classic Maya civilization. A suite of leaf wax δD values was plotted against the original sediment core chronology, which was developed using radiocarbon dates on terrestrial macrofossils. The leaf wax results also indicated major hydrological variability over the past 3000 years, but were not temporally coherent with the other climate proxy records. Leaf wax radiocarbon ages are 400 to 1200 years older than terrestrial macrofossil radiocarbon ages from the same depths, suggesting that leaf waxes are retained in the watershed for extended periods prior to deposition in the lake. We fit a 2nd-order polynomial equation to the depth profile of leaf wax radiocarbon ages (r2 =0.99) and refit the leaf wax δD profile to this “leaf wax age model”. This approach yielded much greater coherence with mineralogical and carbonate isotopic proxy records, including evidence for a period of severe drought (35‰ D-enrichment) from 750 to 1000 A.D. Our results indicate that long-term storage of leaf waxes in drainage basin soils can lead to temporal inaccuracies in leaf wax stable isotope records. These inaccuracies, however, can be corrected using a

  2. Growth Rate Estimates of Supergene Manganese Nodule by 40Ar/39Ar Isotopic Dating

    Institute of Scientific and Technical Information of China (English)

    Li Jianwei; Vasconcelos P M

    2004-01-01

    Increasing world-class, high-grade, and metals-enriched supergene manganese ore deposits have been discovered in the last two decades, making them more and more economically important. However, data on the timing and duration of their formation are sparse, mainly due to the difficulties extracting datable minerals suited to traditional radiometric dating methods. Hollandite, cryptomelane, coronadite, todorokite, and manjiroite are common manganese oxide minerals in supergene environments. These minerals host potassium of variable amounts from 0.1 wt% to 5.0 wt% in their structural sites. This geochemical property provides possibility to date supergene manganese ores by using K-Ar and 40Ar/39Ar methods. In this study, we perform 40Ar/39Ar dating on a 7.1-cm-thick botryoidal manganese nodule from an ancient weathering profile at Mount Tabor, central Queensland, Australia. Laser microprobe incremental analyses of distinct growth bands, from the inner core through the intermediate bands to the outermost crusts of the nodule, have yielded high quality 40Ar/39Ar ages at 27.3 Ma, 20.9 Ma, 19.2 Ma, and 16.1 Ma, respectively. The age results permit preliminary estimates on the average growth rates of the nodule varying from 4.7×10-3 mm/ka to 7.6×10-3 mm/ka to 9.0×10-3 mm/ka, from the core to the rim. Results of this study are of significance in our understanding of the mode, mechanism, process, and climatic conditions in the formation of supergene manganese ore deposits.

  3. Os isotope dating and growth hiatuses of Co-rich crust from central Pacific

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Up to now, accurate determination of the growth age and hiatuses of the Co-rich crust is still a difficult work, which constrains the researches on the genesis, growth process, controlling factors, regional tectonics, paleo-oceanographic background, etc. of the Co-rich crust. This paper describes our work in determining the initial growth age of the Co-rich crust to be of the late Cretaceous Campanian Stage (about 75-80 Ma), by selecting the Co-rich crust with clear multi-layer structures in a central Pacific seamount for layer-by-layer sample analysis and using a number of chronological methods, such as Co flux dating, dating by correlation with 187Os/188Os evolution curves of seawater, and stratigraphic divi- sion by calcareous nannofossils. We have also discovered growth hiatuses with different time intervals in the early Paleocene, middle Eocene, late Eocene and early-middle Miocene, respectively. These re- sults have provided an important age background for further researches on the Co-rich crust growth process and the paleo-oceanographic environment evolution thereby revealed in the said region.

  4. Evolution of Migmatitic Granulite Complexes: implications from Lapland Granulite Belt, Part II: isotopic dating

    Directory of Open Access Journals (Sweden)

    Pekka Tuisku

    2006-01-01

    Full Text Available The migmatitic metapelites of the Lapland granulite belt (LGB in the NE part of the Fennoscandian Shield represent an arc-related greywacke basin metamorphosed in the granulite facies. Detrital zircons from migmatitic metapelites are derived from 1.94 - 2.9 Ga old acid source rocks (U-Pb SIMS ages. The clustering of detrital zircon ages between 1.97 and 2.2 Ga is problematic, because abundant felsic crust of this age is absent in the shield. The metasediments are characterized by Sm-Nd model ages of ca. 2.3 Ga. A younger, 1905-1880 Ma population of homogeneous zircons was formed during regional metamorphism. The peak high-grade metamorphism took place at ~1900 Ma and the latest chronological record from subsequent decompression and cooling phase is from ca. 1870 Ma. The norite-enderbite series of the LGB represents arc-magmas, which were intruded into the metasediments at ~1920-1905 Ma ago according to zircon U-Pb ages and were probably an important heat source for metamorphism. Older, zoned zircon grains in a quartz norite vein, initial εNd values of 0 to +1 and the continuous spectrum of LILE enrichment in the enderbite-series probably reflect assimilation of metasediments by magmas. Monazite U-Pb ages of migmatitic metasediments in the range 1906-1910±3 Ma overlap the late stage of enderbite intrusion and growth of early metamorphic zircons. Garnet-whole rock Sm-Nd ages from leucosomes in the range 1880-1886±7 Ma are concurrent with the growth of the youngest metamorphic zircons and probably indicate the crystallization of leucosomes of the influence of a fluid liberated from them. Isotopic and petrologic data reveal that the evolution of Lapland Granulite belt from the erosion of source rocks to the generation of a sedimentary basin, its burial, metamorphism and exhumation took place within ca. 60 Ma.

  5. Ab initio calculations of mechanical properties of bcc W-Re-Os random alloys: effects of transmutation of W

    Science.gov (United States)

    Li, Xiaojie; Schönecker, Stephan; Li, Ruihuan; Li, Xiaoqing; Wang, Yuanyuan; Zhao, Jijun; Johansson, Börje; Vitos, Levente

    2016-07-01

    To examine the effect of neutron transmutation on tungsten as the first wall material of fusion reactors, the elastic properties of W1-x-y  Re x  Os y (0  ⩽  x, y  ⩽  6%) random alloys in body centered cubic (bcc) structure are investigated systematically using the all-electron exact muffin-tin orbitals (EMTO) method in combination with the coherent-potential approximation (CPA). The calculated lattice constant and elastic properties of pure W are consistent with available experiments. Both Os and Re additions reduce the lattice constant and increase the bulk modulus of W, with Os having the stronger effect. The polycrystalline shear modulus, Young’s modulus and the Debye temperature increase (decrease) with the addition of Re (Os). Except for C 11, the other elastic parameters including C 12, C 44, Cauchy pressure, Poisson ratio, B/G, increase as a function of Re and Os concentration. The variations of the latter three parameters and the trend in the ratio of cleavage energy to shear modulus for the most dominant slip system indicate that the ductility of the alloy enhances with increasing Re and Os content. The calculated elastic anisotropy of bcc W slightly increases with the concentration of both alloying elements. The estimated melting temperatures of the W-Re-Os alloy suggest that Re or Os addition will reduce the melting temperature of pure W solid. The classical Labusch-Nabarro model for solid-solution hardening predicts larger strengthening effects in W1-y  Os y than in W1-x  Re x . A strong correlation between C‧ and the fcc-bcc structural energy difference for W1-x-y  Re x  Os y is revealed demonstrating that canonical band structure dictates the alloying effect on C‧. The structural energy difference is exploited to estimate the alloying effect on the ideal tensile strength in the [0 0 1] direction.

  6. Ab initio calculations of mechanical properties of bcc W-Re-Os random alloys: effects of transmutation of W.

    Science.gov (United States)

    Li, Xiaojie; Schönecker, Stephan; Li, Ruihuan; Li, Xiaoqing; Wang, Yuanyuan; Zhao, Jijun; Johansson, Börje; Vitos, Levente

    2016-06-03

    To examine the effect of neutron transmutation on tungsten as the first wall material of fusion reactors, the elastic properties of W1-x-y  Re x  Os y (0  ⩽  x, y  ⩽  6%) random alloys in body centered cubic (bcc) structure are investigated systematically using the all-electron exact muffin-tin orbitals (EMTO) method in combination with the coherent-potential approximation (CPA). The calculated lattice constant and elastic properties of pure W are consistent with available experiments. Both Os and Re additions reduce the lattice constant and increase the bulk modulus of W, with Os having the stronger effect. The polycrystalline shear modulus, Young's modulus and the Debye temperature increase (decrease) with the addition of Re (Os). Except for C 11, the other elastic parameters including C 12, C 44, Cauchy pressure, Poisson ratio, B/G, increase as a function of Re and Os concentration. The variations of the latter three parameters and the trend in the ratio of cleavage energy to shear modulus for the most dominant slip system indicate that the ductility of the alloy enhances with increasing Re and Os content. The calculated elastic anisotropy of bcc W slightly increases with the concentration of both alloying elements. The estimated melting temperatures of the W-Re-Os alloy suggest that Re or Os addition will reduce the melting temperature of pure W solid. The classical Labusch-Nabarro model for solid-solution hardening predicts larger strengthening effects in W1-y  Os y than in W1-x  Re x . A strong correlation between C' and the fcc-bcc structural energy difference for W1-x-y  Re x  Os y is revealed demonstrating that canonical band structure dictates the alloying effect on C'. The structural energy difference is exploited to estimate the alloying effect on the ideal tensile strength in the [0 0 1] direction.

  7. Ab initio study of interstitial cluster interaction with Re, Os, and Ta in W

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Wahyu; Nandipati, Giridhar; Kurtz, Richard J.

    2017-02-01

    The stability of tungsten self-interstitial atom (SIA) clusters is studied using first-principles methods. Clusters from one to seven SIAs are systematically explored from 1264 unique configurations. Finite-size effect of the simulation cell is corrected based on the scaling of formation energy versus inverse volume cell. Furthermore, the accuracy of the calculations is improved by treating the 5p semicore states as valence states. Configurations of the three most stable clusters in each cluster size n are presented, which consist of parallel [111] dumbbells. The evolution of these clusters leading to small dislocation loops is discussed. The binding energy of size-n clusters is analyzed relative to an n → (n-1) + 1 dissociation and is shown to increase with size. Extrapolation for n > 7 is presented using a dislocation loop model. In addition, the interaction of these clusters with a substitutional Re, Os, or Ta solute is explored by replacing one of the dumbbells with the solute. Re and Os strongly attract these clusters, but Ta strongly repels. The strongest interaction is found when the solute is located on the periphery of the cluster rather than in the middle. The magnitude of this interaction decreases with cluster size. Empirical fits to describe the trend of the solute binding energy are presented.

  8. The neutron capture cross sections of 186;187;188 Os and their application to Re/Os cosmochronometer

    CERN Document Server

    Fujii, Kaori; Mastinu, P; Milazzo, P M

    2009-01-01

    The aim of this thesis is a fine determination of 186;187;188Os neutron capture cross sections, in order to remove principal nuclear physics uncertainties on the age of the universe determined using the Re/Os cosmochronometer. A general introduction including stellar nucleosynthesis, nuclear cosmochronometry,available neutron facilities and neutron reaction features is given. Dedicated measurements of the 186;187;188Os capture cross sections have been performed at the CERN neutron time-of- ight facility, n TOF, in the neutron energy range from 1 eV up to 1 MeV. The details of the measurement and the data treatment are reported. Using obtained capture yields, resolved resonance region analysis is completed. Resonance parameters have been extracted from a full R-matrix fit. A statistical analysis has been performed and the related averaged resonance parameters are derived. This information is crucial for a complete understanding and modelling in terms of the Hauser-Feshbach statistical model of the capture and ...

  9. Using Dissolved Organic Carbon Isotopes for Groundwater Age Dating in Southern Nevada, USA

    Science.gov (United States)

    Thomas, James; Hershey, Ronald; Fereday, Wyatt

    2016-04-01

    Dissolved organic carbon (DOC) 14C offers a method to calculate groundwater ages that is more straightforward than dissolved inorganic carbon (DIC) 14C. To obtain corrected DIC 14C groundwater ages requires models that account for chemical and physical processes that affect both 13C and 14C. This is especially true in carbonate-rock aquifers where a fair amount of dissolution and precipitation of carbonate minerals can occur. A first important step in calculating 14C DOC groundwater ages is to determine the initial 14C DOC (A0) values of the groundwater recharge. For this study, recharge area groundwater samples of DOC 14C, collected from 14 different sites, were used to determine the recharge DOC 14C values. These values ranged from 96 to 120 percent modern carbon (pmc), with an average value of 106.2 pmc. These 14C A0 values support the use of a 100 pmc 14C A0 pre-bomb value to calculate DOC 14C groundwater ages for southern Nevada. Several conditions to successfully use DOC 14C to date groundwater need to be met. First, soluble organic carbon content of aquifers needs to be low, so that little DOC is added to the groundwater as it flows from recharge areas down gradient in an aquifer. For this study, volcanic and carbonate aquifer outcrop rocks showed that these rocks contained low soluble organic carbon. Second, it is important that the DOC does not change character down a flow path, which could indicate transformation of DOC along a flow path and/or addition of DOC to the groundwater. Although specific DOC compounds could not be identified for samples collected at four sites, all four groundwater sample spectra show the same general shape over the duration of the HPLC run indicating that the DOC compound composition of groundwater does not significantly change from up-gradient to down-gradient. Third, another factor that could greatly affect DOC 14C groundwater age calculations is matrix diffusion/adsorption of DOC 14C. Laboratory experiments showed that

  10. Weathering processes and dating of soil profiles from São Paulo State, Brazil, by U-isotopes disequilibria.

    Science.gov (United States)

    Bonotto, Daniel Marcos; Jiménez-Rueda, Jairo Roberto; Fagundes, Isabella Cruz; Filho, Carlos Roberto Alves Fonseca

    2017-01-01

    This study reports the use of the U-series radionuclides (238)U and (234)U for dating two soil profiles. The soil horizons developed over sandstones from Tatuí and Pirambóia formations at the Paraná sedimentary basin, São Paulo State, Brazil. Chemical data in conjunction with the (234)U/(238)U activity ratios (AR's) of the soil horizons allowed investigating the U-isotopes mobility in the shallow oxidizing environment. Kaolinization and laterization processes are taking place in the profiles sampled, as they are especially common in regions characterized by a wet and dry tropical climate and a water table that is close to the surface. These processes are implied by inverse significant correlations between silica and iron in both soil profiles. Iron oxides were also very important to retain uranium in the two sites investigated, helping on the understanding of the weathering processes acting there. (238)U and its progeny (234)U permitted evaluating the processes of physical and chemical alteration, allowing the suggestion of a possible timescale corresponding to the Middle Pleistocene for the development of the more superficial soil horizons.

  11. Magnetostratigraphic dating of an intensification of glacial activity in the southern Italian Alps during Marine Isotope Stage 22

    Science.gov (United States)

    Muttoni, Giovanni; Ravazzi, Cesare; Breda, Marzia; Pini, Roberta; Laj, Carlo; Kissel, Catherine; Mazaud, Alain; Garzanti, Eduardo

    2007-01-01

    We applied magnetostratigraphy and mammal biostratigraphy to date climate-sensitive pollen cycles and lithostratigraphic units of the Pliocene-Pleistocene Leffe sedimentary succession from the Southern Alps, Italy. The Leffe section was correlated to additional sections (Casnigo, Fornaci di Ranica, and Pianengo) to construct a stratigraphic network along a common fluviatile system (the Serio River) sourced in the Southern Alps and flowing southward into the Po River Basin. We obtained a coherent scenario of climate variability for the last ˜ 2 Myr. At Leffe, lacustrine deposition commenced during the Olduvai Normal Subchron (1.94-1.78 Ma) and lasted up to a chronologic level compatible with Marine Isotope Stage (MIS) 22 (0.87 Ma). Pollen analysis revealed that climate varied cyclically from warm-temperate to cool during this time interval, but never as cold as during glacial intervals. At around MIS 22, climate cooled globally. Gravels, attributed to high-energy braided river systems fed locally by alluvial fans, prograded from the Serio River catchment area over the Leffe Basin and toward the Po Plain in response to a generalized event of vegetation withdrawal and enhanced physical erosion. At this time, Alpine valley glaciers reached their first maximum southward expansion with glacier fronts located at only ˜ 5 km upstream from Leffe.

  12. Fluid inclusion characteristics and molybdenite Re-Os geochronology of the Qulong porphyry copper-molybdenum deposit, Tibet

    Science.gov (United States)

    Li, Yang; Selby, David; Feely, Martin; Costanzo, Alessandra; Li, Xian-Hua

    2017-02-01

    The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China's largest porphyry copper system, with ˜2200 million tonnes of ore comprising 0.5 % Cu and 0.03 % Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite units, which intruded into Jurassic volcanic units in a post-collisional (Indian-Asian) tectonic setting. Field observations and core logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and core logging and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ˜425 °C under lithostatic pressure, while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 °C. The fluid inclusion data presented here suggests that there has been ˜2.3 km of erosion at Qulong after its formation, and this erosion may be related to regional uplift of the Lhasa Terrane.

  13. Assessing the transformation of chlorinated ethenes in aquifers with limited potential for natural attenuation: added values of compound-specific carbon isotope analysis and groundwater dating.

    Science.gov (United States)

    Amaral, Helena I F; Aeppli, Christoph; Kipfer, Rolf; Berg, Michael

    2011-10-01

    The evaluation of biotransformation of chlorinated ethenes (CEs) in contaminated aquifers is challenging when variable redox conditions and groundwater flow regime are limiting factors. By using compound-specific stable carbon isotope analysis (C-CSIA) and ³H-³He based groundwater dating, we assessed three CE-contaminated field sites that differed in groundwater flow velocities, redox conditions, and level of contamination. CE isotopic signatures and carbon isotopic mass balances were applied to quantify CE transformation, whereas groundwater dating allowed determining degradation timescales and assessing hydrodynamic regimes. The combination of these techniques enabled at all field sites to indicate zones within the aquifers where CE dechlorination preferably occurred, sometimes even to metabolites of no toxic concern. However, the natural transformation processes were insufficient to mitigate the entire CE contamination at the studied sites. Such situations of limited transformation are worldwide far more common than sites where optimal natural (mainly redox) conditions are enabling complete CEs degradation. Despite such constraints for natural transformation, this study showed that even under non-favorable biogeochemical CEs degradation, the combination of CSIA and groundwater dating provide valuable information to the understanding of the fate of the CEs, thus, being an important contribution in the definition of efficient remediation measures at any given biogeochemical conditions.

  14. Combined in-situ Trace Element, Pb, Sr Isotope Analysis and U-Th Dating of Speleothems and Ostracods

    Science.gov (United States)

    Jochum, K. P.; Scholz, D.; Mertz-Kraus, R.; Gleixner, G.; Guenther, F.; Schwalb, A.; Kuzmin, D.; Stoll, B.; Weis, U.; Izmer, A. V.; Andreae, M. O.

    2010-12-01

    Terrestrial and marine calcium carbonate deposits, such as speleothems and corals, can be used as high-resolution paleoclimate archives. A promising new application is the investigation of ostracod shells. We have developed a LA-ICP-MS technique for combined in-situ trace element, isotope (208Pb/206Pb, 207Pb/206Pb, 87Sr/86Sr) and 230Th-232Th-234U-238U analysis in carbonates. High spatial resolution is obtained by using small spot sizes of 12 - 100 µm. The technique has been applied to a stalagmite from Hüttenbläserschachthöhle, western Germany, and ostracod shells found in lake sediments from Lake Nam Co, Tibet. We focused on a 4 mm long section of the stalagmite that grew continuously for 400 years at 106,000 years B.P. The section includes a transition from aragonite to calcite. Spatial resolution of the trace element analyses is 12 µm corresponding to a temporal resolution of about 1 year. The speleothem calcite is characterized by high Mg (~ 2,000 µg g-1), low Sr (~ 30 µg g-1), Ba (~ 4 µg g-1) and U (~0.04 µg g-1), whereas aragonite has low Mg (~10 µg g-1), high Sr (~ 700 µg g-1), Ba (~ 50 µg g-1) and U (~ 8 µg g-1). Thorium and REE abundances are very low in the ng g-1 range. Calcitic sections probably reflect periods of high recharge, whereas aragonitic sections correspond to dry climate. Remarkable in this context is the steady increase of U, Ba, Sr, Y, Pb, Cd and 208Pb/206Pb in aragonite towards the transition. This may reflect progressively more humid conditions, finally leading to precipitation of calcite. In the U-rich section of the stalagmite, in-situ U-Th-dating by LA-ICP-MS was performed, however, with significantly larger uncertainties of the activity ratios (ca. 3 %) compared to high-precision MC-ICP-MS data (ca. 0.2 %). We also analyzed very small (ca. 0.5 - 1 mm) and thin (about 0.05 mm) ostracod shells from eight levels of a Holocene lake sediment core. 34 major and trace element concentrations could be determined by EPMA and LA

  15. Palaeoecological caracterisation of the mammoth steppe at Final Pleistocene in Central Ukraine from zooarchaeology, stable isotope analyses and direct radiocarbon dating

    Science.gov (United States)

    Péan, Stéphane; Drucker, Dorothée.; Bocherens, Hervé; Haesaerts, Paul; Valladas, Hélène; Stupak, Dmytro; Nuzhnyi, Dmytro

    2010-05-01

    In the Central Ukraine area of the Middle Dnipro Basin, including the Desna river valley, there are exceptional Upper Palaeolithic open air sites with mammoth bone dwelling structures. Mezhyrich is one of these settlements, which are attributed to the Epigravettian cultural facies and occurred in a periglacial environment, during Oxygen Isotope Stage (OIS) 2. Mammoth bone buildings are surrounded by pits, which are filled with archaeological material (tools, hunting weapons, ivory and bone ornaments) and bones of mammoth and other large mammals such as hare, fox, wolf, horse. A new site Buzhanka 2 has yielded a pit which could be related to an expected dwelling structure. These Final Pleistocene sites are particularly appropriate to shed new light upon the relation between man and environment at the time of the mammoth steppe disappearance. Multidisciplinar studies have been carried on, to cross results from zooarchaeology of the pit contents, carbon and nitrogen stable isotope (13C and 15N) analyses of bone collagen, direct 14C dates on mammal bones and microstratigraphic analyses of the loessic sediment. With almost twenty 14C dates available, from mammoth and wolf bones and from charcoals, Mezhyrich is the best dated Epigravettian mammoth bone dwelling site: around 14 500 years BP. Mammoth treatment is zooarchaeologically evidenced in Buzhanka 2, but limited excavated areas do not allow to interpret their procurement yet. In Mezhyrich, consumption of mammoth meat is evidenced from the pit contents, coming from a few juveniles and young adults, probably hunted. The bones used in the dwelling structure no. 4, which are attributed to at least 37 individuals, have two different origins: mostly isolated elements gathered from other deposits, natural accumulations or previous kill sites; a few skeletal portions in anatomical position taken from at least one quite freshly dead mammoth body, for instance a hunted individual. From the stable isotope analyses, it appears

  16. Evaluating Re-Os systematics in organic-rich sedimentary rocks in response to petroleum generation using hydrous pyrolysis experiments

    Science.gov (United States)

    Rooney, A.D.; Selby, D.; Lewan, M.D.; Lillis, P.G.; Houzay, J.-P.

    2012-01-01

    Successful application of the 187Re–187Os geochronometer has enabled the determination of accurate and precise depositional ages for organic-rich sedimentary rocks (ORS) as well as establishing timing constraints of petroleum generation. However, we do not fully understand the systematics and transfer behaviour of Re and Os between ORS and petroleum products (e.g., bitumen and oil). To more fully understand the behaviour of Re–Os systematics in both source rocks and petroleum products we apply hydrous pyrolysis to two immature hydrocarbon source rocks: the Permian Phosphoria Formation (TOC = 17.4%; Type II-S kerogen) and the Jurassic Staffin Formation (TOC = 2.5%; Type III kerogen). The laboratory-based hydrous pyrolysis experiments were carried out for 72 h at 250, 300, 325 and 350 °C. These experiments provided us with whole rock, extracted rock and bitumen and in some cases expelled oil and asphaltene for evaluation of Re–Os isotopic and elemental abundance. The data from these experiments demonstrate that the majority (>95%) of Re and Os are housed within extracted rock and that thermal maturation does not result in significant transfer of Re or Os from the extracted rock into organic phases. Based on existing thermodynamic data our findings suggest that organic chelating sites have a greater affinity for the quadravalent states of Re and Os than sulphides. Across the temperature range of the hydrous pyrolysis experiments both whole rock and extracted rock 187Re/188Os ratios show small variations (3.3% and 4.7%, for Staffin, respectively and 6.3% and 4.9% for Phosphoria, respectively). Similarly, the 187Os/188Os ratios show only minor variations for the Staffin and Phosphoria whole rock and extracted rock samples (0.6% and 1.4% and 1.3% and 2.2%). These isotopic data strongly suggest that crude oil generation through hydrous pyrolysis experiments does not disturb the Re–Os systematics in ORS as supported by various studies on natural systems. The

  17. Assessing TNT and DNT groundwater contamination by compound-specific isotope analysis and 3H-3He groundwater dating: a case study in Portugal.

    Science.gov (United States)

    Amaral, Helena I F; Fernandes, Judite; Berg, Michael; Schwarzenbach, René P; Kipfer, Rolf

    2009-10-01

    Trinitrotoluene (TNT) and dinitrotoluene (DNT) originating from 50 years of explosives production have heavily contaminated two stacked aquifers in the vicinity of Lisboa, Portugal. To assess if these poly-nitroaromatic compounds (P-NACs) are being degraded in the subsurface, tracer-based groundwater dating techniques combined with compound-specific isotope analyses (CSIA) were applied. The groundwater residence times were distinctly different in the two aerobic aquifers, as determined by the tritium ((3)H)-(3)He method. In the contaminated zones, the upper aquifer exhibited groundwater ages of 25 years, whereas the lower (presumably confined) aquifer contained hardly any tritium which indicates water ages >55 years. P-NACs-containing waste waters are known to have leaked into the upper, unconfined aquifer. However, P-NACs were present in both aquifers in high concentrations (up to 33000 microg L(-1) TNT), which implies a hydraulic connection, although tritium concentrations and chemical data suggest two separated aquifers. Based on the (3)H-(3)He groundwater dating and the presence of very high P-NAC concentrations, the contamination of the lower aquifer must have happened during the early stage of the explosive production, i.e. >50 years ago. Despite this 'old' contamination, TNT and DNT have not been transformed until to date as is demonstrated by the negligible changes in their carbon isotopic signatures (delta(13)C). Thus, P-NACs are very recalcitrant to degradation at the investigated site. If the aquifers remain aerobic, TNT and DNT are expected to persist in the subsurface for many decades to centuries. The presented approach of assessing time scales of natural attenuation at the field scale by the combination of CSIA and (3)H-(3)He water dating has the potential to be applied to any other groundwater contaminants, such as chlorinated hydrocarbons, gasoline components, heterocyclic carbenes, or polyaromatic hydrocarbons.

  18. Geology, mineralization, U-Pb dating and Sr-Nd isotope geochemistry of intrusive bodies in northeast of Kashmar

    Directory of Open Access Journals (Sweden)

    Alireza Almasi

    2015-04-01

    Full Text Available Alireza Almasi1, Mohammad Hassan Karimpour1*, Khosrow Ebrahimi Nasrabadi1, Behnam Rahimi1, Urs KlÖtzli2 and Jose Francisco Santos3 Introduction The study area is located in central part of the Khaf- Kashmar-Bardeskan belt which is volcano-plutonic belt at the north of the Dorouneh fault in the north of Lut block. The north of the Lut block is affected by tectonic rotation and subduction processes which occur in the east of Iran (Tirrul et al., 1983. The magmatism of Lut block begins in Jurassic and continues in Tertiary (Aghanabati, 1995. Karimpour (Karimpour, 2006 pointed out the Khaf-Kashmar-Bardeskan belt has significant potential for IOCG type mineralization such as Kuh-e-Zar, Tannurjeh, and Sangan (Karimpour, 2006; Mazloumi, 2009. The data gathered on the I-type intrusive rocks include their field geology, petrography, U–Pb zircon dating and Sr–Nd isotope and also alteration and mineralization in the study area. Materials and methods - Preparation of 150 thin sections of rock samples for study of petrography and alteration of the intrusive rocks. - Magnetic susceptibility measuring of intrusive rocks. - U-Pb dating in zircon of I-type intrusive rocks by Laser-Ablation Multi Collector ICP-MS method. - Sr-Nd analysis on 5 samples of I-type intrusive rocks by Multi-Collector Thermal Ionization Mass Spectrometer (TIMS VG Sector 54 instrument. - Mineralography and paragenetic studies of ore-bearing quartz veins and geochemical analysis for 28 samples. - Production of the geology, alteration and mineralization maps by scale: 1:20000 in GIS. Results Oblique subduction in southern America initiated an arc-parallel fault and shear zones in the back of continental magmatic arc (Sillitoe, 2003. Because of this event, pull-apart basins were formed and high-K to shoshonitic calc-alkalineI- and A-type magmatism occur (Sillitoe, 2003. Most important deposits accompany with this magmatism are Au-Cu deposits types and Fe-Skarns (Sillitoe, 2003. We have

  19. Beta-decay half-lives of new neutron-rich isotopes of Re, Os and Ir approaching the r-process path near N = 126

    Energy Technology Data Exchange (ETDEWEB)

    Kurtukian-Nieto, T.; Benlliure, J.; Casarejos, E.; Fernandez-Ordonez, M.; Pereira, J. [Universidade de Santiago de Compostela, Departamento de Fisica de Particulas, Santiago de Compostela (Spain); Schmidt, K.H.; Becker, F.; Borzov, I.N.; Henzlova, D.; Yordanov, O. [GSI-Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Audouin, L. [Institut de Physique Nucleaire, Orsay (France); Blank, B.; Giovinazzo, J.; Jurado, B. [CNRS/IN2P3-Universite de Bordeaux, Centre d' Etudes Nucleaires de Bordeaux-Gradignan, Gradignan (France); Farget, F. [GANIL, CAEN Cedex 5 (France); Langanke, K.; Martinez-Pinedo, G. [GSI-Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); TU Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany)

    2014-09-15

    Heavy neutron-rich nuclei close to N = 126 were produced by fragmentation of a 1A GeV {sup 208}Pb beam at the FRS at GSI. The β-decay half-lives of 7 nuclides have been determined using a novel numerical analysis method. The half-lives of {sup 202,199}Ir, {sup 200,199}Os and {sup 196}Re are reported for the first time. The comparison of the data with model calculations provides indications on the importance of first-forbidden transitions on the β-decay of nuclei around N = 126 and Z < 82. (orig.)

  20. A comparison of selected Precambrian Brazilian chromitites: Chromite, PGE-PGM, and Re/Os as parental source indicators

    Science.gov (United States)

    Girardi, V. A. V.; Ferrario, A.; Correia, C. T.; Diella, V.

    2006-03-01

    Mineralogical and geochemical studies were carried out in chromitites belonging to the mafic-ultramafic bodies of Niquelândia, Luanga, and Campo Formoso, which are, respectively, included in the Goiás Massif and the Amazon and São Francisco cratons. The main platinum-group minerals (PGM) included or associated with chromite grains are laurite in Niquelândia and Campo Formoso and sperrylite and braggite in Luanga. The most common primary base metal sulfides (BMS) are pentlandite, chalcopyrite, and minor pyrrhotite. Also present are base metal alloys (BMA), such as awaruite, and the BMS millerite, pyrite, and copper as secondary mineral phases linked to later alteration process. The Luanga chromites display the lowest Cr 2O 3/Al 2O 3 and Cr 2O 3/FeO t ratios. The chondrite-normalized profiles are strongly enriched in the platinum PGE subgroup (PPGE, Pt, Pd, Rh). The average Pd/Ir ratio (24.2) and 187Os/ 188Os values (0.17869-0.18584) are very high. Niquelândia chromites have higher Cr 2O 3/Al 2O 3 and Cr 2O 3/FeO t ratios than Luanga. Its PGE contents are low and chondrite-normalized profiles depleted, mainly in the PPGE subgroup. The average Pd/Ir ratio (0.45) and 187Os/ 188Os values (0.12598-0.12777) are low. Campo Formoso chromites have the highest Cr 2O 3/Al 2O 3 and Cr 2O 3/FeO t ratios; its average Pd/Ir ratio (0.72) and chondrite-normalized profiles (except the pronounced Ru spike) are closer to those of Niquelândia. The remarkable differences in terms of chromite bulk-composition, PGE contents and patterns, Pd/Ir ratios, and 187Os/ 188Os values associated with probable distinctions in the inferred geochemical compositions of the respective parental magmas indicate that the Luanga and Niquelândia complexes originated from distinct parental sources. Geochemical and isotopic features indicate that Luanga chromitites and associated rocks are consistent with a parental magma, either originated from an enriched mantle reservoir or strongly contaminated

  1. Evolution of chemical and isotopic composition of inorganic carbon in a complex semi-arid zone environment: Consequences for groundwater dating using radiocarbon

    Science.gov (United States)

    Meredith, K. T.; Han, L. F.; Hollins, S. E.; Cendón, D. I.; Jacobsen, G. E.; Baker, A.

    2016-09-01

    Estimating groundwater age is important for any groundwater resource assessment and radiocarbon (14C) dating of dissolved inorganic carbon (DIC) can provide this information. In semi-arid zone (i.e. water-limited environments), there are a multitude of reasons why 14C dating of groundwater and traditional correction models may not be directly transferable. Some include; (1) the complex hydrological responses of these systems that lead to a mixture of different ages in the aquifer(s), (2) the varied sources, origins and ages of organic matter in the unsaturated zone and (3) high evaporation rates. These all influence the evolution of DIC and are not easily accounted for in traditional correction models. In this study, we determined carbon isotope data for; DIC in water, carbonate minerals in the sediments, sediment organic matter, soil gas CO2 from the unsaturated zone, and vegetation samples. The samples were collected after an extended drought, and again after a flood event, to capture the evolution of DIC after varying hydrological regimes. A graphical method (Han et al., 2012) was applied for interpretation of the carbon geochemical and isotopic data. Simple forward mass-balance modelling was carried out on key geochemical processes involving carbon and agreed well with observed data. High values of DIC and δ13CDIC, and low 14CDIC could not be explained by a simple carbonate mineral-CO2 gas dissolution process. Instead it is suggested that during extended drought, water-sediment interaction leads to ion exchange processes within the top ∼10-20 m of the aquifer which promotes greater calcite dissolution in saline groundwater. This process was found to contribute more than half of the DIC, which is from a mostly 'dead' carbon source. DIC is also influenced by carbon exchange between DIC in water and carbonate minerals found in the top 2 m of the unsaturated zone. This process occurs because of repeated dissolution/precipitation of carbonate that is dependent on

  2. Uranium-lead dating method at the Pará-Iso isotope geology laboratory, UFPA, Belém - Brazil

    Directory of Open Access Journals (Sweden)

    Robert S. Krymsky

    2007-03-01

    Full Text Available Analytical procedures for U-Pb isotope dilution analyses at the Pará-Iso isotope geology laboratory of the Federal University of Pará (UFPA are described in detail. The procedures are applied to zircon, titanite, rutile, apatite, columbite-tantalite and whole rock. Reagent preparation and chemical processing are done in clean-room conditions. Samples are dissolved using TeflonTM microcapsules in steel jacket TeflonTM Parr InstrumentTM bomb or TeflonTM screw cap containers. U and Pb are separated using anion exchange AG 1x8 resin columns. Typical blanks for mineral sample amounts of 0.01 to 1.0 mg are less than 1 pg U and 20-30 pg Pb. Isotope analysis of the U and Pb from the same filament are carried out using a Finnigan MAT 262 mass-spectrometer in static and dynamic modes. The current analytical level is demonstrated on analyses of international standard zircon 91500 with three different 235U-205Pb and 235U-208Pb isotope tracers and whole rock standards. Results of analyses of two zircon samples are also presented.Os procedimentos analíticos para análises U-Pb por diluição isotópica no Laboratório de Geologia Isotópica (Pará-Iso da Universidade Federal do Pará (UFPA são descritos detalhadamente. Esses procedimentos são aplicados para análises de zircão, titanita, rutilo, apatita, columbita-tantalita e rocha total. A purificação dos reagentes e os procedimentos químicos são feitos em salas limpas. As amostras são dissolvidas em microcápsulas de Teflon em bombas do tipo Parr InstrumentTM. U e Pb são separados em colunas com resina de troca iônica AG 1x8. Os brancos de procedimento para amostra típica(0,01-1 mg são menores que 1 pg de U e 20-30 pg de Pb. As análises isotópicas de Pb e de U são feitas em um único filamento de Re em um espectrômetro de massa Finnigan MAT 262 nos modos estático e dinâmico. O nível analítico atual é comprovado pelas análises do padrão internacional de zircão 91500, usando tr

  3. Sm-Nd dating and Nd-Sr isotopic characteristics of the Shimian ophiolite suite, Sichuan Province

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By measuring the Sm-Nd and Rb-Sr isotopic compositions of harzburgite and gabbro from Shimian ophiolite suite, we got the whole rock Sm-Nd isochron age of (938±30) Ma (2?), and the ??Nd of 7.6±0.8 (2?), which shows that the ophiolite was formed at the Early Neoproterozoic. The obvious change (0.70209-0.70708) of ISr values of the ophiolite is caused by the meteoric hydrothermal alteration. The high ? Nd values indicate that the primitive magma was derived from the intense depleted mantle reservoir. It is suggested that this area was in a back-arc basin environment during the Early Neoproterozic.

  4. U-Pb zircon and Re-Os molybdenite geochronology from La Caridad porphyry copper deposit: insights for the duration of magmatism and mineralization in the Nacozari District, Sonora, Mexico

    Science.gov (United States)

    Valencia, V. A.; Ruiz, J.; Barra, F.; Geherls, G.; Ducea, M.; Titley, S. R.; Ochoa-Landin, L.

    2005-03-01

    Uranium-lead zircon (laser ablation multi-collector ICP-MS spot analysis) ages from La Caridad porphyry copper deposit in the Nacozari District, Northeastern Sonora, Mexico, suggest a short period of magmatism, between 55.5 and 52.6 Ma. Two U-Pb ages from the mineralized quartz monzonite unit, showing different textural characteristics, yielded indistinguishable crystallization ages (~54 Ma), and indicate that the intrusion responsible for the mineralization occurred as a single large complex unit, instead of multiple pulses of magmatism. Some zircons analyzed also show inherited ages in cores recording dates of 112-124 Ma, 141-166 Ma and 1.4 Ga. The Re-Os molybdenite ages from the potassic and phyllic hydrothermal alteration veins yielded identical ages within error, 53.6±0.3 Ma and 53.8±0.3 Ma, respectively (weighted average of 53.7±0.21 Ma), supporting a restricted period for the mineralization. The geochronological data thus indicate a short-lived magmatic and hydrothermal system. The inherited zircons of Precambrian and Late Jurassic-Mid Cretaceous age found in the intrusive rocks of La Caridad deposit, can be explained considering two possible scenarios within the tectonic/magmatic evolution of the area. The first scenario considers the presence of a Precambrian anorogenic granitic basement that is intruded by Mesozoic (Jurassic-Cretaceous) units present beneath the La Caridad deposit. The second scenario suggests that the Mesozoic Glance Conglomerate Formation of Arizona underlies the Paleocene volcanic-igneous pile in the La Caridad area.

  5. Reassessment of the 13C/12C and 14C/12C isotopic fractionation ratio and its impact on high-precision radiocarbon dating

    Science.gov (United States)

    Fahrni, Simon M.; Southon, John R.; Santos, Guaciara M.; Palstra, Sanne W. L.; Meijer, Harro A. J.; Xu, Xiaomei

    2017-09-01

    The vast majority of radiocarbon measurement results (14C/12C isotopic ratios or sample activities) are corrected for isotopic fractionation processes (measured as 13C/12C isotopic ratios) that occur in nature, in sample preparation and measurement. In 1954 Harmon Craig suggested a value of 2.0 for the fractionation ratio b that is used to correct 14C/12C ratios for shifts in the 13C/12C ratios and this value has been applied by the radiocarbon community ever since. While theoretical considerations suggest moderate deviations of b from 2.0, some measurements have suggested larger differences (e.g. b = 2.3, measured by Saliège and Fontes in 1984). With the high precision attained in radiocarbon measurements today (±2‰), even a relatively small deviation of b from 2.0 can impact the accuracy of radiocarbon data, and it is, therefore, of interest to re-evaluate the fractionation corrections. In the present study, the fractionation ratio b was determined by independent experiments on the chemical reduction of carbon dioxide (CO2) to elemental carbon (graphitization reaction) and on the photosynthetic uptake of CO2 by C3 and C4 plants. The results yielded b = 1.882 ± 0.019 for the reduction of CO2 to solid graphite and b = 1.953 ± 0.025 for the weighted mean of measurements involving C3 and C4 photosynthesis pathways. In addition, the analysis of over 9600 full-sized OX-I and OX-II normalizing standards measured between 2002 and 2012 confirms b values lower than 2.0. The obtained values are in good agreement with quantum mechanical estimates of the equilibrium fractionation and classic kinetic fractionation as well as with results from other light three-isotope systems (oxygen, magnesium, silicon and sulfur). While the value of the fractionation ratio varies with the relative importance of kinetic and equilibrium fractionation, the values obtained in the present study cluster around b = 1.9. Our findings suggest that a significant fraction of all samples

  6. Dating and source determination of volcanic rocks from Khunik area (South of Birjand, South Khorasan using Rb-Sr and Sm-Nd isotopes

    Directory of Open Access Journals (Sweden)

    Somayeh Samiee

    2016-12-01

    Full Text Available The Khunik area is located in the south of Birjand, Khorasan province, in the eastern margin of Lut block. Tertiary volcanic rocks have andesite to trachy-andesite composition. Dating analyzing by Rb-Sr method on plagioclase and hornblende as well as whole-rock isochron method was performed on pyroxene-hornblende andesite rock unit. On this basis the emplacement age is Upper Paleocene (58±11 Ma. These rocks have initial 87Sr/86Sr and εNd 0.7046-0.7049 and 2.16-3.12, respectively. According to isotopic data, volcanic rocks originated from depleted mantle and have the least crust contamination while it was fractionated. Geochemically, Khunik volcanic rocks have features typical of calk-alkaline to shoshonite and are metaluminous. Enrichment in LILEs and typical negative anomalies of Nb and Ti are evidences that the volcanic rocks formed in a subduction zone and active continental margin. Modeling suggests that these rocks were derived dominantly from 1–5% partial melting of a mainly spinel garnet lherzolite mantle source that is metasomatized by slab-derived fluid.

  7. Combined U-decay Series and Oxygen Isotope Dating of a Mid-Pleistocene Lacustrine Sequence: The Amora Formation, Dead Sea Basin, Israel

    Science.gov (United States)

    Torfstein, A.; Haase-Schramm, A.; Waldmann, N.; Kolodny, Y.; Stein, M.

    2007-12-01

    Dating of mid-Pleistocene carbonate sediments is challenged by the lack of suitable absolute radiometric methods. Here, we present a combined approach that utilized the U and Th isotopes with floating δ18O stratigraphy and paleomagnetic constraints, and established a high-resolution chronology of the mid to upper Pleistocene Lake Amora in the Dead Sea basin. The application of the δ18O record as a floating chronometer is based on the correlation found between δ18O values of synchronously deposited upper-Pleistocene and Holocene lake sediments, East Mediterranean foraminifers and Judean Mountains speleothems (Kolodny et al., 2005). The lacustrine Amora Formation consists of laminated aragonite and detritus, Ca-sulfate minerals, halite and clastic units. The sediments were depsoited in the lacustrine environment of the paleo-Dead Sea basin and were later uplifted and tilted by the rising Sedom diapir, exposing ~330 m of the formation on the eastern flanks of Mt. Sedom. δ18O values range between 6.0 and -1.0‰, shifting periodically between glacial and interglacial sequences throughout the sedimentary section, marking corresponding shifts in the global marine records. Paleomagnetic data indicate the entire section was deposited after the 780 ka Matuyama-Brunhes magnetic transition. Data compilation renders the age of the base of the exposed Amora Fm. to be ~750 to 700 ka BP (MIS 18 to 17), and the age of its capping sediments to be between ~200 and 130 ka BP (MIS 6 and the transition to MIS 5). Climatic-limnologic shifts throughout the sedimentation period are recorded by the lithological, chemical and isotopical properties of the sediments, and are correlated to global and regional events. A prominent ~6 meter thick salt layer precipitated during MIS 11 (~400 ka BP) and marks a significant lake level decline. The only other time a similar salt unit precipitated from the Dead Sea basin lakes during last ~750 ka, was before ~10 ka (Pleistocene-Holocene transition

  8. Second Quaternary dating workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The second Quaternary dating methods workshop was held at Lucas Heights and sponsored by ANSTO and AINSE. Topics covered include, isotope and thermoluminescence dating, usage of accelerator and thermal ionisation mass spectrometry in environmental studies emphasizing on the methodologies used and sample preparation

  9. Zircon LA-ICP-MS U-Pb dating and Sr-Nd isotope study of the Guposhan granite complex, Guangxi, China

    Institute of Scientific and Technical Information of China (English)

    GU Shengyan; HUA Renmin; QI Huawen

    2007-01-01

    Zircon U-Pb dating by the LA-ICP-MS method was applied to determining the ages of different units of the Guposhan granite complex, among which the East Guposhan unit is 160.8±1.6 Ma, the West Guposhan unit is 165.0±1.9 Ma, and the Lisong unit is 163.0±1.3 Ma in age. Much similarity in ages of the three units has thus proved that the whole Guposhan granite complex was formed in the same period of time. They were the products of large-scale granitic magmatism through crust-remelting in the first stage of the Middle Yanshanian in South China. However, the three units have differences both in petrology and in geochemistry. Besides the differences in major, trace and rare-earth elements, they are distinct in their Rb-Sr and Sm-Nd isotopic compositions. The East Guposhan unit and Lisong unit and its enclaves have a similar (87Sr/86Sr)i value of 0.7064 with an average of εNd(t)=-3.03, indicating that more mantle material was evolved in the magma derivation; whereas the West Guposhan unit has a higher (87Sr/86Sr)i value of 0.7173 but a lower εNd(t) value of -5.00, and is characterized by strong negative Eu anomalies and higher Rb/Sr ratios, suggesting that its source materials were composed of relatively old crust components and new mantle-derived components. In addition, an inherited zircon grain in the East Guposhan unit (GP-1) yielded a 206Pb/238U age of 806.4 Ma, which is similar to the ages of the Jiulin cordierite granite in northern Jiangxi and of the Yinqiao migmatic granite in Guangxi in the HZH granite zone. All this may provide new evidence for Late Proterozoic magmatism in the HZH granite zone.

  10. 油气成藏时间的确定方法%Methods for Dating of Hydrocarbon Accumulation

    Institute of Scientific and Technical Information of China (English)

    陈玲; 张微; 佘振兵

    2012-01-01

    综述了国内外油气藏定年技术的主要原理和方法,并对各种方法的优缺点进行评述。认为油气成藏年代学的研究已由过去的定性、半定量发展到今天的定量同位素测年的新阶段,其中,在负热电离质谱仪以及多接收器电感耦合等离子质谱仪上,开展原油以及与油气成藏相关的沥青、干酪根等的Re—Os同位素测试工作,可以对油气藏直接定年,并给出精确的油气成藏时间。此项技术具有广泛的应用前景。%The basic principles and methods for dating of hydrocarbon accumulation at home and abroad as well as their advantages and disadvantages are reviewed in this paper. It is suggested that the qualitative, semi-quantitative dating of hydrocarbon accumulation in the past has been developed into quantitative radiometric dating of it nowadays. By using negative thermal ionization mass spectrometry (N- TIMS) and the multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS), the Re-Os isotopic dating on materials such as crude oil, bitumen and kerogen that are related to hydrocarbon accumulation can be conducted, directly making dating and giving accurate time of hydrocarbon accumulation. It is of widely prospect for application.

  11. Zircon U-Pb dating, geochemical and Sr-Nd-Hf isotopic characteristics of the Jintonghu monzonitic rocks in western Fujian Province, South China: Implication for Cretaceous crust-mantle interactions and lithospheric extension

    Science.gov (United States)

    Li, Bin; Jiang, Shao-Yong; Lu, An-Huai; Zhao, Hai-Xiang; Yang, Tang-Li; Hou, Ming-Lan

    2016-09-01

    Comprehensive petrological, in situ zircon U-Pb dating, Ti-in-zircon temperature and Hf isotopic compositions, whole rock geochemical and Sr-Nd isotopic data are reported for the Jintonghu monzonitic intrusions in the western Fujian Province (Interior Cathaysia Block), South China. The Jintonghu monzonitic intrusions were intruded at 95-96 Ma. Their Sr-Nd-Hf isotopic compositions are similar to the coeval and nearby enriched lithospheric mantle-derived mafic and syenitic rocks, indicating that the Jintonghu monzonitic rocks were likely derived from partial melting of the enriched mantle sources. Their high Nb/Ta ratios (average 21.6) suggest that the metasomatically enriched mantle components were involved, which was attributed to the modification of slab-derived fluid and melt by the subduction of the paleo-Pacific Plate. The presence of mafic xenoliths, together with geochemical and isotopic features indicates a mafic-felsic magma mixing. Furthermore, the Jintonghu intrusions may have experienced orthopyroxene-, biotite- and plagioclase-dominated crystallization. Crust-mantle interaction can be identified as two stages, including that the Early Cretaceous mantle metasomatism and lithospheric extension resulted from the paleo-Pacific slab subduction coupled with slab rollback, and the Late Cretaceous crustal activation and enhanced extension induced by dip-angle subduction and the underplating of mantle-derived mafic magma.

  12. Reconstructing fluid-flow events in Lower-Triassic sandstones of the eastern Paris Basin by elemental tracing and isotopic dating of nanometric illite crystals

    Science.gov (United States)

    Blaise, Thomas; Clauer, Norbert; Cathelineau, Michel; Boiron, Marie-Christine; Techer, Isabelle; Boulvais, Philippe

    2016-03-01

    Lower- to Middle-Triassic sandstones from eastern Paris Basin were buried to a maximum depth of 2500 m at a paleo-temperature of about 100 °C. They contain extensive amounts of authigenic platy and filamentous illite particles similar to those reported in reservoirs generally buried at 3000 to -5000 m and subjected to temperatures of 120 to -150 °C. To evaluate this unexpected occurrence, such sandstones were collected from drill cores between 1825 and 2000 m depth, and nanometric-sized sub-fractions were separated. The illite crystals were identified by XRD, observed by SEM and TEM, analyzed for their major, trace, rare-earth elements and oxygen isotope compositions, and dated by K-Ar and Rb-Sr. Illite particles display varied growth features in the rock pore-space and on authigenic quartz and adularia that they postdate. TEM-EDS crystal-chemical in situ data show that the illite lath/fiber and platelet morphologies correspond at least to two populations with varied interlayer charges: between 0.7 and 0.9 for the former and between 0.8 and 1.0 for the latter, the Fe/Fe + Mg ratio being higher in the platelets. Except for the deeper conglomerate, the PAAS-normalized REE patterns of the illite crystals are bell-shaped, enriched in middle REEs. Ca-carbonates and Ca-phosphates were detected together with illite in the separates. These soluble components yield 87Sr/86Sr ratios that are not strictly in chemical equilibrium with the illite crystals, suggesting successive fluids flows with different chemical compositions. The K-Ar data of finer <0.05 μm illite separates confirm two crystallization events at 179.4 ± 4.5 and 149.4 ± 2.5 Ma during the Early and Late Jurassic. The slightly coarser fractions contain also earlier crystallized or detrital K-bearing minerals characterized by lower δ18O values. The δ18O of the finest authigenic illite separates tends to decrease slightly with depth, from 18.2 (±0.2) to 16.3 (±0.2)‰, suggesting different but

  13. Uranium/thorium dating of Late Pleistocene peat deposits in NW Europe, uranium/thorium isotope systematics and open-system behaviour of peat layers

    NARCIS (Netherlands)

    Heijnis, H.; Plicht, J. van der

    1992-01-01

    The possibility of dating peat by the uranium-series disequilibrium method is discussed. In principle, this method can be used to date peat to approximately 350 ka. The application of the U/Th disequilibrium method (UTD) on peat provides us with the probability of constructing a new chronology for t

  14. U/Th dating and pollen analysis of a stalagmitic sequence of the isotopic stage 5 (''Galerie des Vervietois, Grotte de Han'' Belgium). Datation uranium/thorium et analyse pollinique d'une sequence stalagmitique du stade isotopique 5 (Galerie des Vervietois, Grotte de Han-sur-Lesse, Belgique)

    Energy Technology Data Exchange (ETDEWEB)

    Quinif, Y. (Faculte Polytechnique de Mons (Belgium)); Bastin, B. (Louvain Univ., Louvain-la-Neuve (Belgium). Unite de Physique Nucleaire)

    1994-01-01

    The stalagmitic body of the 'Galerie des Vervietois' ('Grotte de Han', Belgium) has been sampled by numerous drillings. We present here two series studied by lithostratigraphy, palynology and absolute dating by the uranium series disequilibrium. These series allow one to date and reconstitute the palaeoclimatic sequence from isotopic substage 5.5 to isotopic substage 5.3, emphasizing the climatic deterioration of the isotopic substage 5.4 (Melisey I in the 'Grande Pile' sequence). (authors).

  15. Life history of the individuals buried in the St. Benedict Cemetery (Prague, 15th-18th centuries): insights from (14)C dating and stable isotope (δ(13)C, δ(15)N, δ(18)O) analysis.

    Science.gov (United States)

    Salesse, Kevin; Dufour, Élise; Castex, Dominique; Velemínský, Petr; Santos, Frédéric; Kuchařová, Hedvika; Jun, Libor; Brůžek, Jaroslav

    2013-06-01

    Funerary practices and bioarchaeological (sex and age) data suggest that a mortality crisis linked to an epidemic episode occurred during the fifth phase of the St. Benedict cemetery in Prague (Czech Republic). To identify this mass mortality episode, we reconstructed individual life histories (dietary and mobility factors), assessed the population's biological homogeneity, and proposed a new chronology through stable isotope analysis (δ(13)C, δ(18)O and δ(15)N) and direct radiocarbon dating. Stable isotope analysis was conducted on the bone and tooth enamel (collagen and carbonate) of 19 individuals from three multiple graves (MG) and 12 individuals from individual graves (IG). The δ(15)N values of collagen and the difference between the δ(13)C values of collagen and bone carbonate could indicate that the IG individuals had a richer protein diet than the MG individuals or different food resources. The human bone and enamel carbonate and δ(18)O values suggest that the majority of individuals from MG and all individuals from IG spent most of their lives outside of the Bohemian region. Variations in δ(18)O values also indicate that all individuals experienced residential mobility during their lives. The stable isotope results, biological (age and sex) data and eight (14)C dates clearly differentiate the MG and IG groups. The present work provides evidence for the reuse of the St. Benedict cemetery to bury soldiers despite the funeral protest ban (1635 AD). The Siege of Prague (1742 AD) by French-Bavarian-Saxon armies is identified as the cause of the St. Benedict mass mortality event.

  16. Direct radiometric dating of Limestone from Changxing Permian-Triassic boundary using the Re-Os geochronometer%Re-Os同位素精确厘定长兴“金钉子”灰岩沉积年龄

    Institute of Scientific and Technical Information of China (English)

    赵鸿; 李超; 江小均; 周利敏; 李欣尉; 屈文俊; 杜安道

    2015-01-01

    Re-Os同位素作为一种强有力的技术工具,在黑色页岩沉积时代的精确定年中得到了广泛应用,但是将Re-Os应用于灰岩沉积时代厘定的研究并不多见.本文采用Re-Os同位素分析技术,对我国浙江长兴二叠-三叠纪界线“金钉子”剖面中灰岩样品进行分析,获得了1~6层Re-Os等时线年龄为257.3±4.0 Ma,与7层锆石U-Pb年龄误差范围内相互一致、18~22层Re-Os等时线年龄为253.3±6.0 Ma,与17层锆石U-Pb年龄相互印证、23~24层Re-Os等时线年龄为251.8±4.7 Ma,与25层锆石U-Pb年龄相互吻合.结果表明Re-Os同位素能够实现对灰岩地层沉积时代进行直接厘定,有利于生物地层学与同位素地质年代学的直接比对研究.根据前人对长兴“金钉子”地层沉积环境的研究,本文还对适合进行Re-Os同位素定年的灰岩样品规律性进行了讨论,结果显示还原环境沉积的灰岩更适合进行Re-Os同位素定年,氧化环境沉积的灰岩,不利于其中Re-Os同位素体系封闭,无法得到准确的Re-Os同位素等时线年龄.

  17. Magnetostratigraphy and radio-isotope dating of upper Miocene-lower Pliocene sedimentary successions of the Black Sea Basin (Taman Peninsula, Russia)

    NARCIS (Netherlands)

    Vasiliev, I.; Iosifidi, A.G.; Khramov, A.N.; Krijgsman, W.; Kuiper, K.; Langereis, C.G.; Popov, V.V.; Stoica, M.; Tomsha, V.A.; Yudin, S.V.

    2011-01-01

    We present a new chronology for the upper Miocene to Pliocene deposits of the Black Sea basin based on highresolution magnetostratigraphic data coupled with 40Ar/39Ar dating from the 475 m long Zheleznyi Rog section on the Taman Peninsula (Russia). This section comprises the stratigraphic interval o

  18. Re-Os and U-Pb geochronology of the Laochang Pb-Zn-Ag and concealed porphyry Mo mineralization along the Changning-Menglian suture, SW China: implications for ore genesis and porphyry Cu-Mo exploration

    Science.gov (United States)

    Deng, Xiao-Dong; Li, Jian-Wei; Zhao, Xin-Fu; Wang, Hong-Qiang; Qi, Liang

    2016-02-01

    Numerous polymetallic volcanogenic massive sulfide (VMS), vein, and replacement deposits are distributed along the Changning-Menglian suture zone in Sanjiang Tethyan metallogenic province, SW China. Laochang is the largest Pb-Zn-Ag vein and replacement deposit in this area, with a proven reserve of 0.51 Mt Pb, 0.34 Mt Zn, and 1,737 t Ag. Its age and relationship to magmatic events and VMS deposits in the region, however, have long been debated. In this paper, we present pyrite Re-Os and titanite U-Pb ages aiming to provide significant insights into the timing and genesis of the Pb-Zn-Ag mineralization. Pyrite grains in textural equilibrium with galena, sphalerite, and chalcopyrite from stratabound Pb-Zn-Ag and Cu-bearing Pb-Zn-Ag orebodies have a Re-Os isochron age of 45.7 ± 3.1 Ma (2 σ, mean square weighted deviation (MSWD) = 0.45), whereas titanite grains intergrown with sulfide minerals yield a weighted mean 206Pb/238U age of 43.4 ± 1.2 Ma (2 σ, n = 8). A Mo-mineralized granitic porphyry intersected by recent drilling below the Laochang Pb-Zn-Ag ores yields a zircon U-Pb age of 44.4 ± 0.4 Ma (2 σ, n = 12). Within analytical uncertainties, the ages of the Pb-Zn-Ag deposit and the concealed Mo-mineralized porphyry are indistinguishable, indicating that they are products of a single magmatic hydrothermal system. The results show that Laochang Pb-Zn-Ag deposit is significantly younger than the host mafic volcanic rock (zircon U-Pb age of 320.8 ± 2.7 Ma; 2 σ, n = 12) and Silurian VMS deposits along the Changning-Menglian suture zone, arguing against its origin as a Carboniferous VMS deposit as many researchers claimed. The initial 187Os/188Os ratio (0.540 ± 0.012) obtained from the pyrite Re-Os isochron suggests that metals were likely derived from the granitic porphyry that formed from a hybrid magma due to mixing of crustal- and mantle-derived melts, rather than from the mafic volcanic host rocks as previously thought. Our results favor that the Laochang

  19. Radiocarbon Dating

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A

    2007-12-20

    Radiocarbon dating can be used to determine the age of objects that contain components that were once alive. In the case of human remains, a radiocarbon date can distinguish between a crime scene and an archeological site. Documents, museum artifacts and art objects can be dated to determine if their age is correct for the historical context. A radiocarbon date does not confirm authenticity, but it can help identify a forgery.

  20. Dating Violence

    Science.gov (United States)

    Stader, David L.

    2011-01-01

    Dating violence is a form of student-on-student victimization and is a serious school safety issue. Research indicates that at a minimum, 10 percent of high school students are victims of dating violence in one form or another. Among female high school students that date, some data indicate that as many as 30 percent may be victims of dating…

  1. Dating the Indo-Asia collision in NW Himalaya: constraints from Sr-Nd isotopes and detrital zircon (U-Pb) and Hf isotopes of Paleogene-Neogene rocks in the Katawaz basin, NW Pakistan

    Science.gov (United States)

    Zhuang, Guangsheng; Najman, Yani; Millar, Ian; Chauvel, Catherine; Guillot, Stephane; Carter, Andrew

    2015-04-01

    The time of collision between the Indian and Asian plates is key for understanding the convergence history and the impact on climatic systems and marine geochemistry. Despite much active research, the fundamental questions still remain elusive regarding when and where the Indian plate collided with the Asian plate. Especially in the west Himalaya, the questions become more complex due to disputes on the amalgamation history of interoceanic Kohistan-Ladakh arcs (KLA) with Karakoram of the Asian plate and the Indian plate. Here, we present a result of multiple-isotopic geochemistry and geochronology study in the Katawaz Basin in NW Pakistan, a remnant oceanic basin on the western Indian plate which was the repository for the sediments eroded from the west Himalaya ( Qayyum et al., 1996, 1997a, 1997b, 2001; Carter et al., 2010), to evaluate the time and character of collision in this region. In this study, we analyzed 22 bulk mudstone samples for Sr-Nd isotopes and 11 medium-grained sandstones for detrital zircon (U-Pb) geochronology and Hf isotopes. We constructed the Cenozoic chronology in the Katawaz Basin based on our newly collected detrital zircon U-Pb ages and fission track ages. We present the first record of Katawaz chronology that constrained the Khojak Formation to be current study revealed that the Katawaz sedimentary sequence ranges in age from Eocene to the earliest Miocene. The samples from the Nisai Formation show the 87Sr/86Sr - ɛNd values overlapping those of the end member of the Karakoram of Asian origin, revealing the arrival of Asian detritus on the Indian plate prior to 50 Ma. There are two parallel lines of evidence supporting this conclusion: (1) young zircon grains (Journal of the Geological Society 154, 753-756. Qayyum, M., Lawrence, R.D., Niem, A.R., 1997b. Molasse-Delta-flysch continuum of the Himalayan orogeny and closure of the Paleogene Katawaz Remnant Ocean, Pakistan. International geology review 39, 861-875. Qayyum, M., Niem, A

  2. Refinement of the time-space evolution of the giant Mio-Pliocene Río Blanco-Los Bronces porphyry Cu-Mo cluster, Central Chile: new U-Pb (SHRIMP II) and Re-Os geochronology and 40Ar/39Ar thermochronology data

    Science.gov (United States)

    Deckart, Katja; Clark, Alan H.; Cuadra, Patricio; Fanning, Mark

    2013-01-01

    Representing one of the largest known (estimated >5 Gt at 1 % Cu and 0.02 % Mo) porphyry system, the Río Blanco-Los Bronces deposit incorporates at least five hypabyssal intrusive and hydrothermal centres, extending for about 5 km from the Río Blanco and Los Bronces mines in the north, through the Don Luis mine, to the Sur Sur mine, La Americana and Los Sulfatos in the south. The new geochronology data, which now include data on different molybdenite vein types, confirm the U-Pb ages of the pre-mineralisation intrusions but slightly increase their age range from 8.8 to 8.2 Ma. The distinct magmatic pulses of the mineralisation-associated porphyritic intrusives (Late Porphyries) indicate an age interval instead of the previously suggested individual ages: the quartz monzonite porphyry ranges from 7.7 to 6.1 Ma (Sur Sur 5.74 ± 0.13 Ma), the feldspar porphyry shows an interval from 5.8 to 5.2 Ma and the Don Luis porphyry from 5.2 to 5.0 Ma. The new Re-Os data on distinct molybdenite vein types confirm the protracted history of Cu(-Mo) mineralisation, inferred previously. The vein development occurred at least from 5.94 to 4.50 Ma, indicating a time-span of 1.5 Ma for the hydrothermal activity. Hydrothermal minerals dated by the 40Ar/39Ar method are generally too young to record the age of early, high-temperature mineralisation. The majority of the 40Ar/39Ar data in the Río Blanco porphyry cluster record reheating by either the youngest member of the Late Porphyry suite or the post-mineralisation dacite or rhyolite plug formations at around 4.9-4.7 Ma.

  3. Improvements in 230Th dating, 230Th and 234U half-life values, and U-Th isotopic measurements by multi-collector inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Cheng, Hai; Lawrence Edwards, R.; Shen, Chuan-Chou; Polyak, Victor J.; Asmerom, Yemane; Woodhead, Jon; Hellstrom, John; Wang, Yongjin; Kong, Xinggong; Spötl, Christoph; Wang, Xianfeng; Calvin Alexander, E.

    2013-06-01

    We have developed techniques for measuring 234U and 230Th on Faraday cups with precisions of 1-3 epsilon units (1 ɛ-unit=1 part in 104) using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Using a Thermo-Scientific Neptune with desolvation nebulization, we obtained ionization/transmission efficiencies of 1-2% for both U and Th. We set up protocols to correct for tailing, prepared U and Th gravimetric standards, tested a Th mass fractionation correction procedure based on U isotopes, and identified natural calcite samples likely to be in U-Th isotopic secular equilibrium. The measured atomic ratios, 234U/238U=54.970 (±0.019)×10-6 and 230Th/238U=16.916 (±0.018)×10-6, for these calcite samples were identical within errors (quoted 2σ uncertainties calculated combining all sources of error). Half-life values calculated from these ratios are consistent with previous values, but have much smaller errors: 245,620±260 a for 234U and 75,584±110 a for 230Th (quoted 2σ uncertainties calculated using all sources of error). In calculating a 230Th age, some of the systematic errors included in estimating the full error in the half-lives effectively cancel. Removing these uncertainties (uncertainty in the 238U half-life value, uncertainty in our gravimetric uranium and thorium standards, and uncertainty in the absolute isotopic composition of the uranium standard), yields effective uncertainties for the purposes of 230Th dating of ±70 a for the 234U half-life value and ±30 a for the 230Th half-life value. Under ideal circumstances, with our methods, the 2σ uncertainty in age, including uncertainty in half-life values is ±10 a at 10 ka, ±100 a at 130 ka, ±300 a at 200 ka, ±1 ka at 300 ka, ±2 ka at 400 ka, ±6 ka at 500 ka, and ±12 ka at 600 ka. The isotopic composition of a sample with an age determined independent of the Sanbao Cave ages, the observed co-variation between stalagmite δ18O and Northern Hemisphere summer insolation is

  4. SHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon SHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 467±4 Ma, which is the oldest and most reliable magmatic age in this area. Zircon 176Hf/177Hf ratios range from 0.282615 to 0.282657, with εHf(t) values of 5.02±0.28, indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the "Central Uplift" of the Qiangtang, northern Tibetan Plateau.

  5. 40Ar/39Ar dating, geochemistry, and isotopic analyses of the quaternary Chichinautzin volcanic field, south of Mexico City: implications for timing, eruption rate, and distribution of volcanism

    Science.gov (United States)

    Arce, J. L.; Layer, P. W.; Lassiter, J. C.; Benowitz, J. A.; Macías, J. L.; Ramírez-Espinosa, J.

    2013-12-01

    Monogenetic structures located at the southern and western ends of the Chichinautzin volcanic field (Trans-Mexican Volcanic Belt, Central Mexico) yield 40Ar/39Ar ages ranging from 1.2 Ma in the western portion of the field to 1.0-0.09 Ma in the southern portion, all of which are older than the volcanic field. These new ages indicate: (1) an eruption rate of 0.47 km3/kyr, which is much lower than the 11.7 km3/kyr previously estimated; (2) that the Chichinautzin magmatism coexisted with the Zempoala (0.7 Ma) and La Corona (1.0 Ma) polygenetic volcanoes on the southern edge of Las Cruces Volcanic Range (Trans-Mexican Volcanic Belt); and confirm (3) that the drainage system between the Mexico and Cuernavaca basins was closed during early Pleistocene forming the Texcoco Lake. Whole-rock chemistry and Sr, Nd, and Pb isotopic data indicate heterogeneous magmatism throughout the history of Chichinautzin activity that likely reflects variable degrees of slab and sediment contributions to the mantle wedge, fractional crystallization, and crustal assimilation. Even with the revised duration of volcanism within the Chichinautzin Volcanic Field, its eruption rate is higher than most other volcanic fields of the Trans-Mexican Volcanic Belt and is comparable only to the Tacámbaro-Puruaran area in the Michoacán-Guanajuato Volcanic Field to the west. These variations in eruption rates among different volcanic fields may reflect a combination of variable subduction rates of the Rivera and Cocos plates along the Middle America Trench, as well as different distances from the trench, variations in the depth with respect to the subducted slab, or the upper plate characteristics.

  6. Methods of isotopic geochronology

    Science.gov (United States)

    Gorokhov, I. M.; Levchenkov, O. A.

    Papers are presented on such topics as the age of the chemical elements; the age of meteorites, the moon, and the earth; isotopic ages of the most ancient terrestrial formations; and the Archean evolution of Enderby Land in the Antarctic as evidenced by isotopic dating. Consideration is also given to a uranium-lead geochronology technique for investigating Precambrian ore deposits, a Pb-Pb technique of zircon dating, and the potentials and limitations of Sm-Nd geochronology.

  7. U-Pb zircon dating, geochemical and Sr-Nd-Hf isotopic compositions of mafic intrusive rocks in the Motuo, SE Tibet constrain on their petrogenesis and tectonic implication

    Science.gov (United States)

    Pan, Fa-Bin; Zhang, Hong-Fei; Xu, Wang-Chun; Guo, Liang; Luo, Bi-Ji; Wang, Shuai

    2016-02-01

    Mafic intrusive rocks are widely exposed in the Motuo tectono-magmatic belt, southeast Lhasa terrane. LA-ICP-MS U-Pb zircon dating shows that they have magma crystallization ages of 69 and ca. 50 Ma. These mafic intrusive rocks are characterized by variable SiO2 (44.60-57.60 wt.%), high Al2O3 (17.19-20.86 wt.%), and low MgO (1.85-5.38 wt.%) with Mg# of 31-55. Their chemical composition is comparable with low-MgO high-Al basalts to basaltic andesites. They are enriched in LILEs (Rb, Ba, K) and LREE and depleted in HFSEs (Nb, Ta, Zr, Hf, Ti), with weakly evolved Sr-Nd-Hf compositions (whole-rock (87Sr/86Sr)0 = 0.7064 to 0.7086, εNd(t) = - 3.41 to + 1.22, and zircon εHf(t) = - 3.8 to + 6.4). The mafic rocks were derived from partial melting of metasomatized lithospheric mantle. Geochemical and Sr-Nd-Hf isotopic data show that they were insignificantly modified during magma emplacement. We provide a different secular evolution of the lithospheric mantle beneath the eastern part relative to the central part of the southern Lhasa terrane. Sr-Nd isotopic composition of the Motuo Late Cretaceous-Eocene mafic rocks argues that they were derived from partial melting of a relatively homogeneous and depleted lithospheric mantle. We propose that the Late Cretaceous delamination resulted in the replacement of ancient lithospheric mantle by the juvenile homogeneous lithospheric mantle in the eastern Lhasa terrane. The foundered ancient materials may subsequently re-fertilize the lithospheric mantle not only in the eastern Lhasa terrane but also in the surrounding areas.

  8. The chronostratigraphy of the Haua Fteah cave (Cyrenaica, northeast Libya) - Optical dating of early human occupation during Marine Isotope Stages 4, 5 and 6.

    Science.gov (United States)

    Jacobs, Zenobia; Li, Bo; Farr, Lucy; Hill, Evan; Hunt, Chris; Jones, Sacha; Rabett, Ryan; Reynolds, Tim; Roberts, Richard G; Simpson, David; Barker, Graeme

    2017-04-01

    The paper presents the results of optical dating of potassium-rich feldspar grains obtained from the Haua Fteah cave in Cyrenaica, northeast Libya, focussing on the chronology of the Deep Sounding excavated by Charles McBurney in the 1950s and re-excavated recently. Samples were also collected from a 1.25 m-deep trench (Trench S) excavated during the present project below the basal level of the Deep Sounding. Optically stimulated luminescence (OSL) data sets for multi-grain, single aliquots of quartz for samples from the Middle Trench were previously published. Re-analyses of these OSL data confirm significant variation in the dose saturation levels of the quartz signal, but allow the most robust OSL ages to be determined for comparison with previous age estimates and with those obtained in this study for potassium-rich feldspars from the Deep Sounding. The latter indicate that humans may have started to visit the cave as early as ∼150 ka ago, but that major use of the cave occurred during MIS 5, with the accumulation of the Deep Sounding sediments. Correlations between optical ages and episodes of "Pre-Aurignacian" artefact discard indicate that human use of the cave during MIS 5 was highly intermittent. The earliest phases of human activity appear to have occurred during interstadial conditions (5e and 5c), with a later phase of lithic discard associated with more stadial conditions, possibly MIS 5b. We argue that the "Pre-Aurignacian" assemblage can probably be linked with modern humans, like the succeeding "Levalloiso-Mousterian" assemblage; two modern human mandibles associated with the latter are associated with a modelled age of 73-65 ka. If this attribution is correct, then the new chronology implies that modern humans using "Pre-Aurignacian" technologies were in Cyrenaica as early as modern humans equipped with "Aterian" technologies were in the Maghreb, raising new questions about variability among lithic technologies during the initial phases of

  9. Timing and sources of granite magmatism in the Ribeira Belt, SE Brazil: Insights from zircon in situ U-Pb dating and Hf isotope geochemistry in granites from the São Roque Domain

    Science.gov (United States)

    Janasi, Valdecir de Assis; Andrade, Sandra; Vasconcellos, Antonio Carlos B. C.; Henrique-Pinto, Renato; Ulbrich, Horstpeter H. G. J.

    2016-07-01

    Eight new in situ U-Pb zircon age determinations by SHRIMP and LA-MC-ICPMS reveal that the main granitic magmatism in the São Roque Domain, which is largely dominated by metaluminous high-K calc-alkaline monzogranites with subordinate peraluminous leucogranites, occurred between 604 ± 3 and 590 ± 4 Ma. This small temporal range is ca. 20-30 Ma younger than previously admitted based on U-Pb TIMS dates from literature, some of which obtained in the same occurrences now dated. The observed discrepancy seems related to the presence of small Paleoproterozoic inherited cores in part of the zircon populations used for TIMS multigrain dating, which could also respond for the unusually high (up to 10 Ma) uncertainty associated with most of these dates. The younger age range now identified for the São Roque granite magmatism has important implications for the evolution of the Ribeira Fold Belt. Whilst previously admitted ages ca. 620-630 Ma substantiated correlations with the widespread and intensely foliated high-K calc-alkaline granitoid rocks of the neighbor Socorro-Guaxupé Nappe (potentially associated with an accretionary continental margin), the ˜600-590 Ma interval seems more consistent with a late deformation tectonic setting. Strongly negative ɛHf(t) characterize the magmatic zircons from the São Roque Domain granites. An eastward increase from -22 in the São Roque Granite to -11 in the Cantareira Granite and neighboring stocks suggests an across-domain shift in granite sources. Such eastward younging of sources, also indicated by Sm-Nd isotope data from granites and supracrustal sequences in neighboring domains, is suggestive that some of the first-order limits and discontinuities in this belt are not defined by the strike-slip fault systems traditionally taken to separate distinct domains. Although the negative ɛHf(t) and ɛNd(t) indicate sources with long crustal residence for all studied granite plutons, the observed range is more radiogenic than the

  10. Geochronology and isotope geochemistry of the Baogutu porphyry copper deposit in the West Junggar region, Xinjiang, China

    Science.gov (United States)

    Shen, Ping; Shen, Yuanchao; Pan, Hongdi; Li, Xian-hua; Dong, Lianhui; Wang, Jingbin; Zhu, Heping; Dai, Huawu; Guan, Weina

    2012-04-01

    The Baogutu copper deposit, a newly-discovered middle-sized porphyry copper deposit, is located in the West Junggar region of Xinjiang, NW China. Baogutu is associated with a Late Carboniferous intrusive complex that was emplaced into Lower Carboniferous volcano-sedimentary strata. The intrusive complex comprises main-stage diorites and minor late-stage diorite porphyries. Their intrusive activity occurred in 313.0 ± 2.2 Ma to 312.3 ± 2.2 Ma based on U-Pb zircon SIMS analyses. Molybdenite separated from ore-bearing quartz veins yields Re-Os model ages from 309.4 ± 4.4 Ma to 314.1 ± 4.5 Ma with a weighted mean age of 312.4 ± 1.8 Ma. Biotites, separated from fresh diorite and hydrothermal breccias in main-stage diorites, yield 40Ar/39Ar plateau ages of 308.26 ± 1.88 and 305.69 ± 1.76 Ma, respectively. These dates obtained from three independent dating techniques constrain the ore-forming age of the Baogutu deposit. Stable isotopes (H, O, S) and radiogenic isotope (Pb) have been used to discriminate the sources of the ore-forming fluid at Baogutu. The δ18O (1.14-1.74‰) and δD (-74‰ to -98‰) data indicate that the water of the ore-forming fluids was derived from magmatic water. The δ34S values (-0.24‰ to +0.4‰) show that the sulfur isotope composition of the ore fluids is characterized by magma sulfur. Lead isotope compositions (206Pb/204Pb = 17.92-18.89, 207Pb/204Pb = 15.45-15.62, 208Pb/204Pb = 37.68-38.36) indicate that the lead of the ore fluids is derived from the mantle. These data confirm the occurrence of a Cu-Au-Mo mineralizing event at Late Carboniferous in the Baogutu region and the ore-forming fluids are mainly derived from the mantle. The event is inferred to be associated with Late Carboniferous Junggar oceanic crust subduction.

  11. Timing and characteristics of Late Pleistocene and Holocene wetter periods in the Eastern Desert and Sinai of Egypt, based on 14C dating and stable isotope analysis of spring tufa deposits

    Science.gov (United States)

    Hamdan, Mohamed A.; Brook, George A.

    2015-12-01

    There is very little dated evidence on wet periods in the Eastern Desert and Sinai Peninsula of Egypt during the Late Pleistocene and Holocene. To obtain such information, we have studied the petrography, isotope geochemistry and AMS radiocarbon ages of mostly relict tufas deposited by springs draining perched ground water bodies in metamorphic and volcanic rocks. The tufas unconformably overly Precambrian basic igneous rocks (basalt, diabase and gabbro). As the ages of tufa carbonate are frequently older than the true ages of the deposits because of the incorporation of old, 14C-dead carbon, we have dated both the carbonate matrix and insoluble organic material of the tufas. These ages show that the tufas were largely formed during two broad time periods, the most recent from 12,058 to 6678 cal yr BP (African Humid Period), and the other from ˜31,200-22,500 cal yr BP, with preferential growth during the coldest times of this period namely during Heinrich Events 2 and 3 (H2 and H3) and the Last Glacial Maximum (LGM). The time span between 19,000-9000 cal yr BP, including the YD and H1, appears to have been relatively more arid than the earlier LGM or H2 periods or the later Holocene. The Late Pleistocene tufas are depleted in 18O relative to the Holocene tufas and were deposited at a lower temperature (˜14.0°-20.8 °C vs. 18.4°-23.4 °C). We believe that the Holocene tufas in the Sinai were formed by rainfall from the Mediterranean and those in the southern part of the Eastern Desert by African monsoon rainfall derived from the Red Sea-Gulf of Aden and Indian Ocean. In contrast, the moisture that fed the Late Pleistocene tufas, which are depleted in 18O relative to Holocene deposits, and progressively depleted from north to south, was probably brought by the Westerlies from the Atlantic-Mediterranean Sea when the Westerly circulation was pushed southwards during the coldest periods of the Late Pleistocene. Periods of tufa deposition correlate with major

  12. K-Ar dating, whole-rock and Sr-Nd isotope geochemistry of calc-alkaline volcanic rocks around the Gümüşhane area: implications for post-collisional volcanism in the Eastern Pontides, Northeast Turkey

    Science.gov (United States)

    Aslan, Zafer; Arslan, Mehmet; Temizel, İrfan; Kaygusuz, Abdullah

    2014-04-01

    Volcanic rocks from the Gümüşhane area in the southern part of the Eastern Pontides (NE Turkey) consist mainly of andesitic lava flows associated with tuffs, and rare basaltic dykes. The K-Ar whole-rock dating of these rocks range from 37.62 ± 3.33 Ma (Middle Eocene) to 30.02 ± 2.84 Ma (Early Oligocene) for the andesitic lava flows, but are 15.80 ± 1.71 Ma (Middle Miocene) for the basaltic dykes. Petrochemically, the volcanic rocks are dominantly medium-K calc-alkaline in composition and show enrichment of large ion lithophile elements, as well as depletion of high field strength elements, thus revealing that volcanic rocks evolved from a parental magmas derived from an enriched mantle source. Chondrite-normalized rare-earth element patterns of the volcanic rocks are concave upwards with low- to-medium enrichment (LaCN/LuCN = 3.39 to 12.56), thereby revealing clinopyroxene- and hornblende-dominated fractionations for andesitic-basaltic rocks and tuffs, respectively. The volcanic rocks have low initial 87Sr/86Sr ratios (0.70464 to 0.70494) and ɛNd(i) values (+1.11 to +3.08), with Nd-model ages (TDM) of 0.68 to 1.02 Ga, suggesting an enriched lithospheric mantle source of Proterozoic age. Trace element and isotopic data, as well as the modelling results, show that fractional crystallization and minor assimilation played an important role in the evolution of the volcanic rocks studied. The Eocene to Miocene volcanism in the region has resulted from lithospheric delamination and the associated convective thinning of the mantle, which led to the partial melting of the subduction-metasomatized lithospheric mantle.

  13. Atom and pre-history: the geological framework of fossil man in the light of dating and isotopic data; L`atome au service de la prehistoire: le cadre geologique de l`homme fossile a la lumiere des datations et des donnees isotopiques

    Energy Technology Data Exchange (ETDEWEB)

    Miskovsky, J.C. [Universite de Perpignan, 66 - Tautavel (France); Gibert, E. [Paris-11 Univ., 91 - Orsay (France)

    1994-12-31

    The discovery of natural radioactivity and the applications of nuclear physics to the study of sediments and sediment content, allow for the delimitation of the chrono-stratigraphic and paleoclimatic framework of fossil Man. This chronology is based on the development of continental glacial phenomena and is specified through comparison with various methods: paleomagnetic inversion, the variation of oxygen isotopic composition of marine biogenic carbonates and the dating methods. Pleistocene and Holocene era are reviewed. (authors). 9 figs., 90 refs.

  14. Zircon U-Pb ages and Sr-Nd-Hf isotopes of the highly fractionated granite with tetrad REE patterns in the Shamai tungsten deposit in eastern Inner Mongolia, China: Implications for the timing of mineralization and ore genesis

    Science.gov (United States)

    Jiang, Si-Hong; Bagas, Leon; Hu, Peng; Han, Ning; Chen, Chun-Liang; Liu, Yuan; Kang, Huan

    2016-09-01

    The Shamai tungsten deposit is located in the eastern part of the Central Asian Orogenic Belt (CAOB). Tungsten mineralization is closely related to the emplacement of fine- to medium-grained biotite monzogranite (G1) and porphyritic biotite monzogranite (G2) in the Shamai Granite. NW-trending joints and faults host orebodies in the Shamai Granite and Devonian hornfels. The mineralization is characterized by a basal veinlet zone progressing upwards to a thick vein zone followed by a mixed zone, a veinlet zone, and a thread vein zone at the top. The ore-related alteration typically consists of muscovite, greisen, and hornfels. In order to constrain the timing of the Shamai mineralization and discuss the ore genesis, muscovite Ar-Ar, molybdenite Re-Os, and zircon U-Pb geochronological, geochemical, and Sr-Nd-Hf isotopic studies were completed on the deposit. The U-Pb zircon dating yielded weighted mean ages of 153 ± 1 Ma for G1 and 146 ± 1 Ma for G2. Muscovite from a wolframite-bearing quartz vein yielded an Ar-Ar plateau age of 140 ± 1 Ma, whereas two molybdenite samples yielded identical Re-Os model ages of 137 ± 2 Ma. These two ages are younger than the two monzogranites, suggesting a prolonged magmatic-hydrothermal interaction during tungsten mineralization. Major and trace element geochemistry shows that both G1 and G2 are characterized by high SiO2 and K2O contents, high A/CNK values (1.08-1.40), a spectacular tetrad effect in their REE distribution patterns, and non-CHARAC (charge-and-radius-controlled) trace element behavior. This suggests that both G1 and G2 are highly differentiated peraluminous rocks with strong hydrothermal interaction. The Nd-Hf isotope data for the Shamai Granite (εNd(t) between - 1.9 and + 7.4, ɛHf(t) from 5.2 to 12.8) are largely compatible with the general scenario for much of the Phanerozoic granite emplaced in the CAOB. It is here suggested that the Shamai Granite originated from partial melting of a juvenile lower crust with

  15. 锡林浩特杂岩中斜长角闪岩锆石U-Pb年代学及Hf同位素研究%U-Pb Dating and Hf Isotopic Composition of Zircons in Amphibolite from the Xilinhot Complex

    Institute of Scientific and Technical Information of China (English)

    王善辉; 陈岳龙; 李大鹏

    2012-01-01

    锡林浩特杂岩是一套经历强变形变质作用的变质岩,主要由黑云斜长片麻岩、角闪斜长片麻岩、斜长角闪片麻岩及变粒岩夹透镜状或脉状斜长角闪岩组成.查明其形成年龄、变质年龄对深入认识中亚造山带的形成演化具有重要意义.本次研究对锡林浩特杂岩中斜长角闪岩进行了SHRIMP锆石U-Pb测年和LA-MC-ICP-MS锆石Hf同位素组成分析,给出了锆石SHRIMP U-Pb的加权平均年龄为(316 ±4) Ma,该年龄代表斜长角闪岩的原岩形成年龄,表明锡林浩特杂岩不是前寒武纪地质体.通过锆石Hf同位素分析,εHf(t)值主要为正值(+4.1~+17.0),揭示其物源可能来自亏损地幔或壳幔混合.根据亏损地幔和古老地壳的锆石Hf同位素进行两端元的混合计算,得到斜长角闪岩原岩岩浆的源区以幔源增生组分为主体(经过计算壳幔混合比例大约1∶2).部分锆石的模式年龄在1.8 ~2.5 Ga之间,表明斜长角闪岩的原岩在形成过程中有古元古代地壳物质的加入,通过兴蒙造山带和锡林浩特杂岩中斜长角闪岩的Hf模式年龄对比可知,物源可能来自兴蒙造山带内部.基于Hf同位素的两端元混合计算表明该区在晚古生代存在地壳增生.根据野外观察和室内岩石特征分析,该套杂岩可能是一套经历强变形与变质作用的晚古生代火山-沉积建造.%The Xilinhot complex is mainly composed of biotite-plagioclase gneiss, hornblende-plagioclase gneiss, amphibolitic gneiss and granulite with lenticular or vein amphibolite rocks, whose formation and metamorphosed age and petrogenesis have been debating. Accurate determination of its formation and metamorphosed age is of great significance to understanding the formation and evolution of the Hinggan-Mongolia Orogenic Belt. Through zircon SHRIMP U-Pb dating and LA-MC-ICP-MS Hf isotopic analysis on zircons in plagioclase amphibolite from the Xilinhot complex, weighted average value of

  16. Sr, Nd, Pb and Li isotope geochemistry and Ar-Ar dating of alkaline lavas from northern James Ross Island (Antarctic Peninsula) - implications for back-arc magma formation

    Science.gov (United States)

    Kosler, J.; Magna, T.; Mlcoch, B.; Mixa, P.; Hendriks, B. W. H.; Holub, F. V.; Nyvlt, D.

    2009-04-01

    The elemental and isotopic (Sr, Nd, Pb and Li) composition of Cenozoic back-arc alkaline basalts emplaced east of the Antarctic Peninsula in James Ross Island Volcanic Group (JRIVG) is different from the compositions of the fore-arc alkaline volcanic rocks in Southern Shetlands and nearby Bransfield Strait. The variability in elemental and isotopic composition is not consistent with the JRIVG derivation from a single mantle source but rather it suggests that the magma was mainly derived from a depleted mantle with subordinate OIB-like enriched mantle component (EM II). The isotopic data are consistent with mantle melting during extension and possible roll-back of the subducted lithosphere of the Antarctic plate in Miocene to Pliocene times, as indicated by the existing geochronological data and the new Ar-Ar age determinations. Magma contamination by Triassic - Early Tertiary clastic sediments deposited in the back-arc basin was only localized and affected Li isotopic composition in two of the samples, while most of the basalts show very little variation in delta 7Li values, as anticipated for "mantle-driven" Li isotopic composition. These variations are difficult to resolve with radiogenic isotope systematics but Li isotopes may prove sensitive in tracking complex geochemical processes acting through the oceanic crust pile, including hydrothermal leaching and seawater equilibration.

  17. Trace- and rare-earth element geochemistry and Pb-Pb dating of black shales and intercalated Ni-Mo-PGE-Au sulfide ores in Lower Cambrian strata, Yangtze Platform, South China

    Science.gov (United States)

    Jiang, Shao-Yong; Chen, Yong-Quan; Ling, Hong-Fei; Yang, Jing-Hong; Feng, Hong-Zhen; Ni, Pei

    2006-08-01

    The Lower Cambrian black shale sequence of the Niutitang Formation in the Yangtze Platform, South China, hosts an extreme metal-enriched sulfide ore bed that shows >10,000 times enrichment in Mo, Ni, Se, Re, Os, As, Hg, and Sb and >1,000 times enrichment in Ag, Au, Pt, and Pd, when compared to average upper continental crust. We report in this paper trace- and rare-earth-element concentrations and Pb-Pb isotope dating for the Ni-Mo-PGE-Au sulfide ores and their host black shales. Both the sulfide ores and their host black shales show similar trace-element distribution patterns with pronounced depletion in Th, Nb, Hf, Zr, and Ti, and extreme enrichment in U, Ni, Mo, and V compared to average upper crust. The high-field-strength elements, such as Zr, Hf, Nb, Ta, Sc, Th, rare-earth elements, Rb, and Ga, show significant inter-element correlations and may have been derived mainly from terrigenous sources. The redox sensitive elements, such as V, Ni, Mo, U, and Mn; base metals, such as Cu, Zn, and Pb; and Sr and Ba may have been derived from mixing of seawater and venting hydrothermal sources. The chondrite-normalized REE patterns, positive Eu and Y anomalies, and high Y/Ho ratios for the Ni-Mo-PGE-Au sulfide ores are also suggestive for their submarine hydrothermal-exhalative origin. A stepwise acid-leaching Pb-Pb isotope analytical technique has been employed for the Niutitang black shales and the Ni-Mo-PGE-Au sulfide ores, and two Pb-Pb isochron ages have been obtained for the black shales (531±24 Ma) and for the Ni-Mo-PGE-Au sulfide ores (521±54 Ma), respectively, which are identical and overlap within uncertainty, and are in good agreement with previously obtained ages for presumed age-equivalent strata.

  18. Isotopic age dating of the alkaline intrusive complex and its related molybdenum polymetallic deposit at Hekanzi, western Liaoning Province%辽西河坎子碱性侵入杂岩体及钼多金属矿床同位素年代学研究

    Institute of Scientific and Technical Information of China (English)

    刘勇; 聂凤军; 方俊钦

    2012-01-01

    The newly discovered Hekanzi deposit is a medium-size porphyry molybdenum deposit in western Liaoning Province. Intrusive complexes are widely distributed in the study area, with the Mesozoic alkaline and calc-alka-line rocks being the most developed alkaline rocks. They intruded into the Precambrian and Paleozoic volcanic-sedimentary rocks in the forms of batholiths, stocks, and dykes. Alkaline intrusive rocks are mainly miascite, alkaline syenite and alkaline diabase. The calc-alkaline rocks are mainly granite porphyry, granodiorite, biotite granite and K-feldspar granite. Isotopic ages of the Hekanzi alkaline granite and its related Mo polymetallic deposit have been determined. The rock-forming age of the biotite-orthoclase granite is (235.3 ± 1.0) Ma with MSWD value of 0.68. Re-Os isotopic data of six molybdenite separates define a correlation line corresponding to an age of (224.0 ?1.3) Ma with MSWD value of 0.72. The metallic minerals in the ore are pyrite, chalcopy-rite, molybdenite, pyrrhotite, marcasite and a little scheetine. Gangue minerals are mainly calcite, fluorite, garnet, serpentine, peridotite, dolomite, feldspar, plagioclase and quartz. The NE-trending, NS-trending and NW-trending fault zones are widely distributed in the alkaline intrusive complex and its related molybdenum polymetallic deposit at Hekanzi.%对辽西河坎子地区与碱性杂岩体相关的钼多金属矿床进行了同位素年代学研究.所获黑云母正长花岗岩锆石LA-ICP-MS U-Pb同位素加权平均年龄为(235.3±1.0) Ma,MSWD值为0.68;河坎子钼多金属矿床内辉钼矿的Re-Os同位素等时线年龄为(224.0±1.3) Ma,MSWD值为0.72.碱性杂岩体与相关的钼多金属矿床具有密切的空间关系,两者的形成时间亦比较接近,据此可推测,河坎子碱性杂岩体与相关的钼多金属矿床均为印支期构造-岩浆作用及流体活动的产物.印支期内频繁的岩浆-热液活动为该地区内钼、铜、金多金属元素的活

  19. Osmium isotopes and the Upper Devonian "Kellwasser" event

    Science.gov (United States)

    Brauns, M.

    2001-12-01

    The Upper Devonian "Kellwasser" horizon at the Frasnian/Famennian boundary (~367 Ma) records one of the most severe world-wide catastrophic bio-events in Earth's history. Current theories for the causes of mass extinction include (e.g. Schindler 1990) (i) meteoritic impact, (ii) sea-level changes, shifts of the sedimentary realm and generation of anoxic milieus, (iii) enhanced clastic input and modification of sea water chemistry, and, possibly, (iv) a combination of (ii) and (iii). The time-integrated Os isotopic composition of Kellwasser limestones appears to be a suitable tool to shed light on these options and possibly place constraints on the Os isotopic evolution of Upper Devonian sea water. We present complete Re-Os analyses of limestone and shale whole rock samples, and some biogenic/diagenetic constituents (conodonts, Fe oxides). The results indicate extreme Re and Os compositional variations between different limestone and shale sublayers (Re = 0.1 - 40 ppb, Os 26 - 830 ppt, Re/Os = 4 - 240). The present Os isotopic ratios of the rocks were found to be very radiogenic (187Os/186Os = 9,865 - 388,35). For the first time, conodont samples extracted from the Kellwasser sequence were tested as potential tracers for the Os isotopic composition of Upper Devonian sea water. Their Os contents are in the range of 210 - 112 ppt, which required analysis of about 15.000 specimens per sample to obtain sufficient Os for mass spectrometry. The Os of the conodonts (187Os/186Os = 14,35 - 67,89) is significantly less radiogenic compared to their complementary host rocks. Their 187Re/186Os, however, exceed the 187Re/186Os ratios of the host limestones by at least 1-2 orders of magnitude. Recalculation of the 187Re/186Os ratios of all rock and conodont samples for an age of 367 Ma yielded in all cases unrealistic and very contrasting values with respect to any hypothetical Os isotopic composition of Upper Devonian sea water. Our Re-Os isotopic data do establish several points

  20. Formation of Precambrian Strata in Shandong Province——Isotopic Dating Evidences%山东省前寒武纪地层形成时代——同位素地质测年的证据

    Institute of Scientific and Technical Information of China (English)

    王世进; 万渝生; 宋志勇; 杨恩秀; 董春艳; 王伟

    2011-01-01

    As showed by precise isotopic dating results,Yishui group was formed in the 2760~2700Ma,while Yanlingguan formation in Taishan group,Xiayazu formation and Mengjiatun formation in Liuhang group were formed in 2750~2700Ma.They all belong to early period of Neoarchean.Shangya formation and Shancaoyu formation of Liuhang formation in Taishan group were formed in 2600~2540Ma(intruded by quartz diorite rock units in Yishan rock group and monzogranite in Aolaishan rock group),while zircons ages of Jining group was(2561±24)Ma.They all belong to the late Archean.The formation period of Jingshan group and Fenzishan group is late Paleoproterozoic.Detrital zircon U-Pb age of Zhifu group was(1658±32) Ma and(1792±43)Ma.They were formed in the Mesoproterozoic.Detrital zircon U-Pb age of Huaguoshan group is 800~740Ma,and was formed in the Neoproterozoic.%精确同位素地质测年结果表明,沂水岩群形成时代为2 760~2 700Ma,泰山岩群雁翎关岩组、柳杭岩组下亚组和孟家屯岩组形成时代为2 750~2 700Ma,均属新太古代早期;泰山岩群柳杭岩组上亚组、山草峪岩组形成时代为2 600~2 540Ma(被峄山岩套石英闪长岩和傲徕山岩套二长花岗岩侵入),济宁岩群岩浆锆石年龄(2 561±24)Ma,均属新太古代晚期。荆山群和粉子山群的形成时代为古元古代晚期。芝罘群碎屑锆石U-Pb年龄(1 658±32)Ma、(1 792±43)Ma,形成时代为中元古代。云台岩群花果山组碎屑锆石U-Pb年龄800~740Ma,形成时代为新元古代。

  1. Radiocarbon dating of terrestrial carbonates

    Science.gov (United States)

    Pigati, Jeffrey S.; Rink, W. Jack; Thompson, Jeroen

    2014-01-01

    Terrestrial carbonates encompass a wide range of materials that potentially could be used for radiocarbon (14C) dating. Biogenic carbonates, including shells and tests of terrestrial and aquatic gastropods, bivalves, ostracodes, and foraminifera, are preserved in a variety of late Quaternary deposits and may be suitable for 14C dating. Primary calcareous deposits (marls, tufa, speleothems) and secondary carbonates (rhizoliths, fracture fill, soil carbonate) may also be targeted for dating when conditions are favorable. This chapter discusses issues that are commonly encountered in 14C dating of terrestrial carbonates, including isotopic disequilibrium and open-system behavior, as well as methods used to determine the reliability of ages derived from these materials. Recent methodological advancements that may improve the accuracy and precision of 14C ages of terrestrial carbonates are also highlighted.

  2. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20132601 Cui Yurong(Tianjin Institute of Geology and Mineral Resources,China Geological Survey,Tianjin 300170,China);Zhou Hongying In Situ LA-MC-ICP-MS U-Pb Isotopic Dating of Monazite(Acta Geoscientica Sinica,ISSN0375-5444,CN11-1856/P,33(6),2012,p.865-876,6illus.,4tables,41refs.)Key words:monazite,U-Pb dating

  3. Laboratory for Radiokrypton Dating

    Science.gov (United States)

    Lu, Z.; Bailey, K.; Jiang, W.; Müller, P.; O'Connor, T. P.; Zappala, J. C.

    2013-12-01

    Due to its simple production and transport processes in the terrestrial environment, the long-lived noble-gas isotope 81Kr (half-life = 230 kyr) is the ideal tracer for studying old water and ice in the age range of 10^5-10^6 years, a range beyond the reach of 14C. 81Kr dating, a concept pursued in the past four decades by numerous laboratories employing a variety of techniques, is now available for the first time to the earth science community at large. This is made possible by the development of ATTA-3 (Jiang et al., GCA 91, 1-6; 2012), an efficient and selective atom counter based on the Atom Trap Trace Analysis method (Chen et al., Science 286, 1139-1141; 1999). The instrument is capable of measuring both 81Kr/Kr and 85Kr/Kr ratios of environmental samples in the range of 10^-14-10^-10. For 81Kr-dating in the age range of 150 - 1,500 kyr, the required sample size is 5 - 10 micro-L STP of krypton gas, which can be extracted from approximately 100 - 200 kg of water or 40 - 80 kg of ice. For 85Kr/Kr analysis, the required sample size is generally smaller by an order of magnitude because of the isotope's higher initial abundance in the atmosphere. The Laboratory for Radiokrypton Dating is currently equipped to analyze up to 120 samples per year. With future equipment upgrades, this limit can be increased as demand grows. In the period since November 2011, the Laboratory has measured both 81Kr/Kr and 85Kr/Kr ratios in over 50 samples that had been extracted by collaborators from six different continents. The samples were from groundwater wells in the Great Artesian Basin (Australia), Guarani Aquifer (Brazil), and Locust Grove (Maryland); from brine wells of the Waste Isolation Pilot Plant (New Mexico); from geothermal steam vents in Yellowstone National Park; from near-surface ice at Taylor Glacier, Antarctica; and from deep mines in South Africa. Sample collection and purification was performed by groups including the University of Illinois at Chicago, University

  4. Water isotopes in desiccating lichens

    Science.gov (United States)

    Cuntz, Matthias; Máguas, Cristina; Lakatos, Michael

    2009-01-01

    The stable isotopic composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in non-vascular, poikilohydric organisms such as lichens and bryophytes. To understand basic isotope exchange processes of non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrate with the isotopic composition of surrounding water vapour. A model was developed as a proof of concept that accounts for the specific water relations of these poikilohydric organisms. The approach incorporates first their variable thallus water potential and second a compartmentation of the thallus water into two isotopically distinct but connected water pools. Moreover, the results represent first steps towards the development of poikilohydric organisms as a recorder of ambient vapour isotopic composition. PMID:19888598

  5. Study on the Change Law of Stable Nitrogen Isotope in Tissue of Chinese-date%大枣不同组织氮稳定同位素变化规律研究

    Institute of Scientific and Technical Information of China (English)

    王红云; 高占锋; 付才; 黄志国; 常志强; 刘悦

    2015-01-01

    For the reason that:some agricultural products which have higher economic value were often simula-ted by the counterfeiters.It was in urgent need of building theirs source database to insure the safety of agricultural products in order to clear the change laws of stable nitrogen isotope in tissue of Chinese-date,and the effect of such factors as breed,region,and sampling time on δ15 N values of in tissue of Chinese-date,as well as to screen the sam-pling location of Chinese-date in origin traceability,it was measured in this paper δ15 N values in tissue of fructus corni,jujube meat,jujube pit as the research object to Zanhuang jujube and jujube in Tai-hang Mountain main pro-ducing areas such as Zanhuang Country,Xingtang Country,Fuping Country.The results showed that:Under the com-prehensive influence of such factors as breed,region,sampling time and year,the difference of δ15 N value sexsited between breeds of Zanhuang jujube and jujube,Zanhuang jujube was higher than that of jujube;And the change law of the two breeds was different:For Zanhuang jujube,jujube pit >jujube meat(P >0.05) >frctus corni( P >0.05),For jujube:jujube meat >frctus corni(P >0.05) >jujube pit(P <0.05).For the reason that the value ofδ15 N had no significant difference in jujube meat between two breeds,it was suggested that we should take jujube meat as sampling location in origin traceability of Chinese-date.The effects of breed,region,and sampling time onδ15 N of jujub meat was co-operational.%为了打击农产品造假,提高农产品质量安全,急需建立特色农产品的溯源数据库。数据库的建立,首先要建立溯源指标体系。以河北省太行山区大枣主产区赞皇县、行唐县、阜平县的赞皇大枣和婆枣为研究对象,测定其皮、肉、核3个组织中的δ15 N 值,以期明确大枣各组织中 N 同位素的变化规律,以及品种、地域、采摘时期等因素对大枣δ15 N 值的作用,筛选出大枣与产地溯源相

  6. Detection of a meteoritic component in Ivory Coast tektites with rhenium-osmium isotopes

    Science.gov (United States)

    Koeberl, Christian; Shirey, Steven B.

    1993-07-01

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost.

  7. Detection of a meteoritic component in ivory coast tektites with rhenium-osmium isotopes.

    Science.gov (United States)

    Koeberl, C; Shirey, S B

    1993-07-30

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. (i) The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. (ii) Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. (iii) Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost.

  8. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20141014Wang Hairan(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an710069,China);Zhao Hongge Theory and Application of Zircon U-Pb Isotope Dating Technique(Geology and Resources,ISSN1671-1947,CN21-1458/P,22(3),2013,p.229

  9. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20070454 Bao Zengkuan (Institute of High Energy Physics, CAS, Beijing 100049, China); Yuan Wanming Apatite (U-Th)/He Dating and Its Application (Acta Petrologica et Mineralogica, ISSN1000-6524, CN11-1966/P, 24(2), 2005, p.126-132, 2 illus., 25 refs.) Key words: isotopic geochronology

  10. Osmium isotopes and highly siderophile elements in lunar glasses

    Science.gov (United States)

    Horan, M.; Walker, R.; Shearer, C.; Papike, J.

    2003-04-01

    The absolute and relative abundances of the highly siderophile elements (HSE) present in planetary mantles are primarily controlled by silicate-metal partitioning during core-mantle differentiation and by later planetary accretion. Constraints on HSE distributions in the lunar mantle will provide insights to the formation and late accretionary history of not only the Moon, but also Earth. Because no samples of the lunar mantle have been collected, the only materials presently available for constraining mantle abundances are lunar volcanic rocks. The Apollo 15 green and Apollo 17 orange glasses are spherules derived from fire-fountain eruptions of mare basalts. These glasses are more primitive than the mare basalts, and probably were derived by the melting of cumulate assemblages from the lunar magma ocean in the deep interior (> 400 km). Despite our limited understanding of mantle-melt partitioning of the HSE, even for terrestrial systems, these glasses provide the best hope for constraining the HSE composition of the lunar interior. We report Os isotopic composition data and Re, Os, Ir, Ru, Pt and Pd isotope dilution concentration data for green glass (15426,164) and orange glass (74001,1217). Absolute and relative abundances of HSE are variable. The green glass has elemental ratios of the HSE and an Os isotopic composition within the range defined by chondritic meteorites, suggesting that the HSE were dominated by a meteoritic contaminant. This sample probably provides little information about the lunar interior, but may help constrain the types of meteorites impacting the lunar surface. Two size fractions (180-325 mesh and 75-180 mesh) of the orange glass were analyzed. HSE patterns for both size fractions are fractionated, having higher chondrite-normalized abundances of Pt and Pd, compared with Os and Ir. The supra-chondritic 187Os/188Os ratio (0.1339) of the finer fraction indicates modestly fractionated Re/Os relative to chondritic. The coarser size fraction

  11. Osmium isotope evidence for a large Late Triassic impact event

    Science.gov (United States)

    Sato, Honami; Onoue, Tetsuji; Nozaki, Tatsuo; Suzuki, Katsuhiko

    2013-01-01

    Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial Os isotope ratio (187Os/188Osi) of ∼0.477 to unradiogenic values of ∼0.126 in a platinum group element-enriched claystone layer, indicating the input of meteorite-derived Os into the sediments. The timing of the Os isotope excursion coincides with both elevated Os concentrations and low Re/Os ratios. The magnitude of this negative Os isotope excursion is comparable to those found at Cretaceous–Paleogene boundary sites. These geochemical lines of evidence demonstrate that a large impactor (3.3–7.8 km in diameter) produced a global decrease in seawater 187Os/188Os ratios in the Late Triassic. PMID:24036603

  12. Palaeoproterozoic continental arc magmatism, and Neoproterozoic metamorphism in the Aravalli-Delhi orogenic belt, NW India: New constraints from in situ zircon U-Pb-Hf isotope systematics, monazite dating and whole-rock geochemistry

    Science.gov (United States)

    Kaur, Parampreet; Zeh, Armin; Chaudhri, Naveen

    2017-04-01

    Presently, the extent, origin and petrogenesis of late Palaeoproterozoic (ca. 1.85 Ga) magmatism in the north-central Aravalli-Delhi orogenic belt, NW India and subsequent metamorphic overprints are poorly constrained. Results of new in situ zircon U-Pb-Hf isotope analyses in combination with whole-rock elemental and isotopic data provide the first hard evidence that granitoid magmatism occurred in a continental magmatic arc setting between 1.86 and 1.81 Ga. The Hf-Nd model ages of 3.0-2.6 Ga and inherited zircon grains of 3.3-2.5 Ga indicate abundant reworking of Archaean crust. Flat HREE patterns with negative Eu anomalies furthermore reveal that the granitoids were generated from garnet-free and plagioclase-rich sources at shallow depths. Significant isotope variation among granitoid samples (εHft = -3.7 to -9.0; εNdt = -4.8 to -7.9) indicate that the reworked Archaean crust was not completely homogenised during the Palaeoproterozoic. This is best reflected by zircon Hf-isotope variation of ca. 9.5 epsilon units within the oldest granitoid sample. Zircon grains from this sample define three discrete Hf-isotope groups at εHf1.86Ga = -8.9, -4.8 and -1.6. These are interpreted to result from mixing of zircon-saturated magmas derived from three distinct sources within the crust prior to solidification. A monazite U-Pb isochron age of 868 ± 4 Ma from one of the granitoid samples furthermore indicates that the Aravalli fold belt was affected by an important post-magmatic overprint, perhaps related to the widespread metasomatic, granulite metamorphic and/or magmatic events during the same time span.

  13. Abundances and isotopic compositions of rhenium and osmium in pyrite samples from the Huaibei coalfield, Anhui, China

    Science.gov (United States)

    Liu, Gaisheng; Chou, C.-L.; Peng, Z.; Yang, G.

    2008-01-01

    Two pyrite samples from the Shihezi Formation (Lower Permian), Huaibei coalfield, Anhui, China, have been analyzed for abundances and isotopic compositions of rhenium and osmium using negative thermal ion mass spectrometry. The Re-Os ages of the pyrites are 64.4 and 226 Ma, which are younger than the formation age of the coal seam. The pyrite samples may consist of pyrite formed at various stages during the history of coal formation. The ??Osvalues of the two pyrite samples are +17 and +18, respectively. Such high ??Osvalues are reported for the first time for recycles crustal materials from a sedimentary basin. ?? Springer-Verlag 2007.

  14. Suggested terminology for Quaternary dating methods

    Science.gov (United States)

    Colman, Steven M.; Pierce, K.L.; Birkeland, P.W.

    1987-01-01

    Classification of Quaternary dating methods should be based on the level of quantitative information and the degree of confidence contained in the age estimates produced by the dating methods. We recommend the use of the terms numerical-age, calibrated-age, relative-age, and correlated-age to describe these levels. We also classify dating methods by type into sideral, isotopic, radiogenic, chemical and biological, geomorphic, and correlation methods. The use of "absolute" is inappropriate for most dating methods, and should be replaced by "numerical." The use of "date" should be minimized in favor of "age" or "age estimate." We recommend use of the abbreviations ka and Ma for most ages; calender dates can be used where appropriate and yr B.P. can be used for radiocarbon ages. ?? 1987.

  15. Geology and isotopic composition of helium, neon, xenon and metallogenic age of the Jinding and Baiyangping ore deposits, northwest Yunnan, China

    Institute of Scientific and Technical Information of China (English)

    XUE; Chunji(薛春纪); CHEN; Yuchuan(陈毓川); WANG; Denghong(王登红); YANG; Jianmin(杨建民); YANG; Weiguang(杨伟光); ZENG; Rong(曾; 荣)

    2003-01-01

    Both the Jinding and Baiyangping ore deposits developed in the Lanping basin, which is a Mesozoic-Cenozoic terrestrial clastic sedimentary basin. Their occurrences can easily lead many people to compare them with the Pb-Zn deposit hosted in sedimentary rocks, such as Mississippian Valley-, Sedex- and sandstone-type Pb-Zn deposits. However, the Lanping basin developed in the settings of strong tectonic activity of the continental crust, which could cause an effective material exchange between the lower crust and the upper mantle. The orebodies are clearly tectonically controlled without syngenetic features, which probably represents a new type of the sedimentary rock-hosted Pb-Zn deposit. The isotopic compositions of noble gases in ore-forming fluids indicate that 2%-32% of helium (3He/4He = 0.19 Ra-1.97 Ra) is derived from the mantle, 50.1% of neon (20Ne/22Ne = 10.45-10.83; 21Ne/22Ne = 0.03) from the mantle, and considerable amount of xenon (129Xe/130Xe = 5.84-6.86; 134Xe/130Xe = 2.26-2.71) from the mantle, which show that mantle fluids played an important role in the ore formation. The ore-forming age of 67-60 Ma obtained by Re-Os and 40Ar-39Ar dating methods is later than the host rock, which is coeval with the Himalayan alkali magmatism of the mantle source and mantle-crust source. In this paper, the mineralization of the Jinding and Baiyangping ore deposits is considered to be related to the mantle fluids which move upward with the magma or along the deep faults, and mix with the meteoritic brine in the crust to result in large-scale deposition.

  16. Date Rape (For Teens)

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Date Rape KidsHealth > For Teens > Date Rape A A ... Rape en español Violaciones durante citas What Is Date Rape? When people think of rape , they might ...

  17. A Multi-Isotope (B, Sr, O, H, C) and Age Dating (3H-3He, 14C) Study of Ground Water From Salinas Valley, California: Hydrochemistry, Dynamics, and Contamination Processes

    Energy Technology Data Exchange (ETDEWEB)

    Vengosh, A; Gill, J; Davisson, M L; Hudson, B G

    2001-08-01

    The chemical and isotopic ({sup 11}B/{sup 10}B, {sup 87}Sr/{sup 86}Sr, {sup 18}O/{sup 16}O, {sup 2}H/H, {sup 13}C/{sup 12}C, {sup 14}C, {sup 3}He/{sup 3}H) compositions of groundwater from the upper aquifer system of the Salinas Valley in coastal central California were investigated in order to delineate the origin and processes of groundwater contamination in this complex system. The Salinas Valley has a relatively deep, confined ''400-foot'' aquifer, overlain by a ''180-foot'' aquifer, and a shallower perched aquifer, all made up of alluvial sand, gravel, and clay deposits. Groundwater from the aquifers have different {sup 14}C ages; fossil ({sup 14}C = 21.3 pmc) for the 400-foot, and modern ({sup 14}C = 72.2 to 98.2 pmc) for the 180-foot. Fresh groundwater in all aquifers is recharged naturally and artificially and through the Salinas River. The two modes of recharge can be distinguished chemically. We identified several different saline components with distinguishable chemical and isotopic fingerprints. (1) Salt-water intrusion in the northern basin has Cl concentrations up to 1700 mg/l, a Na/Cl ratio seawater, {delta}{sup 11}B between +17 and +38 per mil, and {sup 87}Sr/{sup 86}Sr between 0.7088 and 0.7096. Excess dissolved Ca, relative to the expected concentration for simple dilution of seawater, correlates with {sup 87}Sr/{sup 86}Sr ratios, suggesting base exchange reaction with clay minerals. (2) Agriculture return flow is high in NO{sub 3} and SO{sub 4}, with a {sup 87}Sr/{sup 86}Sr = 0.7082, {delta}{sup 11}B = 19 per mil; and {delta}{sup 13}C between -23 and -17 per mil. The {sup 3}H-{sup 3}He ages (5-17 years) and {sup 14}C data suggest vertical infiltration rates of irrigation water of 3 to 10 m/yr. (3) Non-marine saline water in the southern part of the valley has high TDS up to 3800 mg/l, high SO{sub 4}, Na/Cl ratio >1, {delta}{sup 11}B between +24 and +30 per

  18. Geochemical constraints on the relationship between the Miocene-Pliocene volcanism and tectonics in the Palaoco and Fortunoso volcanic fields, Mendoza Region, Argentina: New insights from 40Ar/39Ar dating, Sr-Nd-Pb isotopes and trace elements

    Science.gov (United States)

    Dyhr, Charlotte T.; Holm, Paul M.; Llambías, Eduardo J.

    2013-10-01

    New 40Ar/39Ar analyses constrain the formation of the volcanic succession of Sierra de Palaoco in the present back-arc of the Andean Southern Volcanic Zone (SVZ), near 36°S, to the Late Miocene and assigns them to the Huincán II Formation. The composition of major and trace elements, Sr, Nd and Pb isotopes of the Palaoco and nearby Río Grande rocks require a strong arc-like component in the mantle that is absent or weak in both Early Miocene (Fortunoso Group) and Pleistocene alkaline lavas (Llancanelo Group) erupted in the same area. We evaluate the relative roles of varying mantle source compositions and crustal contamination in the generation of geochemically very different lavas from the Palaoco, Fortunoso and Río Grande volcanic fields, north of the Payún Matrú Volcano. The source for the Early Miocene Fortunoso(I) basalts was a OIB-type mantle devoid of subduction zone input. This type of OIB-like volcanic activity terminated due to a change from an extensional to a compressional tectonic regime. Towards the end of the Miocene renewed alkaline volcanism at Fortunoso (II) display a transition to arc-type incompatible element enrichment. Shortly after the calc-alkaline Palaoco volcanism started with a very strong geochemical arc-signature including Ba/La ≈ 60 and La/Nb = 2-3. After a quiesence of 1 Ma the major part of the voluminous Late Palaoco basalts were erupted around 7.5 Ma over a few hundred ka. These are less enriched in Ba and Sr and have compositions like many Holocene rocks of the Southern Volcanic Zone. Isotopically the Fortunoso I and Palaoco rocks are distinct. Regional volcanism of the Charilehue, Huincán I and II mostly has a moderate arc-type enrichment indicating incipient arc developments. However, Palaoco and La Brea at (c. 35°S) show full geochemical arc-signature, and we infer that a frontal arc was established. The subsequent development in the Palaoco-Río Grande area encompasses renewed late Pliocene calc-alkaline low volume

  19. High continental weathering rate during Early Cambrian: Evidence from Os isotopic composition of Early Cambrian Ocean

    Science.gov (United States)

    Jiang, S.-Y.; Yang, J.-H.; Ling, H.-F.; Feng, H.-Z.; Chen, Y.-Q.; Chen, J.-H.

    2003-04-01

    The paleo-ocean environmental change during the Precambrian-Cambrian transition is a key issue related to the causes for an explosive radiation of different metazoan phyla during Early Cambrian. The chemical and isotopic compositions of marine sediments and chemical precipitates such as carbonates, phosphorites, siliceous rocks, and black shales record the changing composition and physical conditions of the seawater in which these rocks accumulated. Organic carbon-rich black shales from marine environments are commonly enriched in a number of trace elements such as Ni, Mo, V, Co, Cr, Au, U, As, Pb, Zn, Cu, Re, and platinum-group-elements (PGE). Recent researches have demonstrated that Re-Os isotopes and PGE contents in black shales are useful proxies for seawater chemistry. It is believed that Re and Os in orgainc-carbon rich black shales are mostly hydrogeneous in origin which were largely sequestered from seawater at the time of deposition. In South China, the Lower Cambrian black shale sequence of the Niutitang Formation (and lateral equivalents) exists broadly several thousands kilometers. The lowermost sequence of this formation contain a thin sulfide ore horizon with an apparently unique and extreme case of metal enrichments such as Mo, Ni, Se, Re, Os, As, Hg, Sb, Ag, Au, Pt, and Pd. In this study, we conducted a preliminary investigation of Re-Os isotopes and Plantium Group Element (PGE) distribution patterns of the balck shales and intercalated Ni-Mo polymetallic sulfide bed from Guizhou and Hunan Provinces. The high rOs(t) values of the black shales indicate that the Early Cambrian ocean in Yangtze Platform had a highly radiogenic Os, possibly as a result of high continental weathering rate at that time. The Ni-Mo polymetallic sulfide ores within the black shales have lower rOs(t) values than the black shales, and they show similar REE and PGE patterns as the hydrothermal siliceous rocks within the Lower Cambrian strata, which suggest that the Ni

  20. Leatherback Isotopes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC is currently working on a project identifying global marine isotopes using leatherback turtles (Dermochelys coriacea) as the indicator species. We currently...

  1. Food Product Dating

    Science.gov (United States)

    ... prior to its consumption to determine if the product shows signs of spoilage. [ Top of Page ] What Types of Food are Dated? Open dating is found on most foods including meat, poultry, egg and dairy products. "Closed or coded ...

  2. Retrospective Birth Dating of Cells

    Energy Technology Data Exchange (ETDEWEB)

    L.Spalding, K; Bhardwaj, R D; Buchholz, B A; Druid, H; Frisen, J

    2005-04-19

    The generation of cells in the human body has been difficult to study and our understanding of cell turnover is limited. Extensive testing of nuclear weapons resulted in a dramatic global increase in the levels of the isotope {sup 14}C in the atmosphere, followed by an exponential decrease after the test ban treaty in 1963. We show that the level of {sup 14}C in genomic DNA closely parallels atmospheric levels, and can be used to establish the time point when the DNA was synthesized and cells were born. We use this strategy to determine the age of cells in the cortex of the adult human brain, and show that whereas non-neuronal cells are exchanged, occipital neurons are as old as the individual, supporting the view that postnatal neurogenesis does not take place in this region. Retrospective birth dating is a generally applicable strategy that can be used to measure cell turnover in man under physiological and pathological conditions.

  3. Isotopic chirality

    Energy Technology Data Exchange (ETDEWEB)

    Floss, H.G. [Univ. of Washington, Seattle, WA (United States)

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  4. Isotopic Paleoclimatology

    Science.gov (United States)

    Bowen, R.

    Paleotemperature scales were calculated by H. C. Urey and others in the 1950s to assess past temperatures, and later work using the stable isotopes of oxygen, hydrogen, and carbon employed standards such as Peedee belemnite (PDB) and Standard Mean Ocean Water (SMOW). Subsequently, subjects as diverse as ice volume and paleotemperatures, oceanic ice and sediment cores, Pleistocene/Holocene climatic changes, and isotope chronostratigraphy extending back to the Precambrian were investigated.

  5. Radiometric Dating Does Work!

    Science.gov (United States)

    Dalrymple, G. Brent

    2000-01-01

    Discusses the accuracy of dating methods and creationist arguments that radiometric dating does not work. Explains the Manson meteorite impact and the Pierre shale, the ages of meteorites, the K-T tektites, and dating the Mount Vesuvius eruption. (Author/YDS)

  6. Geological, geochronological, geochemical, and Sr-Nd-O-Hf isotopic constraints on origins of intrusions associated with the Baishan porphyry Mo deposit in eastern Tianshan, NW China

    Science.gov (United States)

    Wang, Yinhong; Xue, Chunji; Liu, Jiajun; Zhang, Fangfang

    2016-10-01

    The Baishan porphyry Mo deposit (0.72 Mt; 0.06 % Mo) is located in the interior of the eastern Tianshan orogenic belt in Xinjiang, NW China. The deposit comprises 15 orebodies that are associated with monzogranite and granite porphyry stocks and are structurally controlled by roughly EW-trending faults. Secondary ion mass spectrometry (SIMS) zircon U-Pb dating of the monzogranite and granite porphyry yielded the Middle Triassic age (228 ± 2 to 227 ± 2 Ma), which coincide with the molybdenite Re-Os model ages ranging from 226 ± 3 to 228 ± 3 Ma. The Triassic monzogranite and granite porphyry belong to high-K calc-alkaline series and are characterized by high SiO2 and Al2O3 and low MgO, TiO2, and P2O5 concentrations, with negative Eu anomalies (δEu = 0.55-0.91). The least-altered monzogranite and granite porphyry yield uniform ɛ Nd( t) values from +1.6 to +3.6, and wide (87Sr/86Sr) i ratios ranging between 0.7035 and 0.7071, indicating that they were derived from the lower crust. In situ O-Hf isotopic analyses on zircon using SIMS and laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) indicate that the δ18O and ɛ Hf( t) values of zircon from a monzogranite sample vary from 6.1 to 7.3 ‰ and +8.0 to +11.7, respectively, whereas zircon from a granite porphyry sample vary from 6.2 to 6.9 ‰ and +7.3 to +11.2, respectively. The geochemical and isotopic data imply that the primary magmas of the Baishan granite were likely derived from partial melts from the lower crust involving some mantle components. The Baishan Mo deposit and granitic emplacement were proposed to be most likely related to post-orogenic lithospheric extension and magmatic underplating. An extensional event coupled with the rising of hot mantle-derived melts triggered partial melting of the lower crust, as well as provided metals (Mo).

  7. Copper isotope signatures in modern marine sediments

    Science.gov (United States)

    Little, Susan H.; Vance, Derek; McManus, James; Severmann, Silke; Lyons, Timothy W.

    2017-09-01

    The development of metal stable isotopes as tools in paleoceanography requires a thorough understanding of their modern marine cycling. To date, no Cu isotope data has been published for modern sediments deposited under low oxygen conditions. We present data encompassing a broad spectrum of hydrographic and redox regimes, including continental margin and euxinic (sulphide-containing) settings. Taken together with previously published data from oxic settings, these data indicate that the modern oceanic sink for Cu has a surprisingly homogeneous isotopic composition of about +0.3‰ (δ65Cu, relative to NIST SRM976). We suggest that this signature reflects one of two specific water-column processes: (1) an equilibrium isotope fractionation between soluble, isotopically heavy, Cu complexed to strong organic ligands and an isotopically light pool sorbed to particles that deliver Cu to the sediment, or (2) an equilibrium isotope fractionation between the same isotopically heavy ligand-bound pool and the particle reactive free Cu2+ species, with the latter being scavenged by particulates and thereby delivered to the sediment. An output flux of about +0.3‰ into sediments is isotopically light relative to the known inputs to the ocean (at around +0.6‰) and the seawater value of +0.6 to +0.9‰, suggesting the presence of an as yet unidentified isotopically light source of Cu to the oceans. We hypothesize that this source may be hydrothermal, or may result from the partial dissolution of continentally derived particles.

  8. Nanoscale variations in 187Os isotopic composition and HSE systematics in a Bultfontein peridotite

    Science.gov (United States)

    Wainwright, A. N.; Luguet, A.; Schreiber, A.; Fonseca, R. O. C.; Nowell, G. M.; Lorand, J.-P.; Wirth, R.; Janney, P. E.

    2016-08-01

    Understanding the mineralogical controls on radiogenic chronometers is a fundamental aspect of all geochronological tools. As with other common dating tools, it has become increasingly clear that the Re-Os system can be impacted by multiple mineral formation events. The accessory and micrometric nature of the Re-Os-bearing minerals has made assessing this influence complex. This is especially evident in cratonic peridotites, where long residence times and multiple metasomatic events have created a complex melting and re-enrichment history. Here we investigate a harzburgitic peridotite from the Bultfontein kimberlite (South Africa) which contains sub-micron Pt-Fe-alloy inclusions within base metal sulphides (BMS). Through the combination of the focused ion beam lift-out technique and low blank mass spectrometry we were able to remove and analyse the Pt-Fe-alloy inclusions for their Re-Os composition and highly siderophile element (HSE) systematics. Six repeats of the whole-rock yield 187Os/188Os compositions of 0.10893-0.10965, which correspond to Re depletion model ages (TRD) of 2.69-2.79 Ga. The Os, Ir and Pt concentrations are slightly variable across the different digestions, whilst Pd and Re remain constant. The resulting HSE pattern is typical of cratonic peridotites displaying depleted Pt and Pd. The Pt-Fe-alloys have PUM-like 187Os/188Os compositions of 0.1294 ± 24 (2-s.d.) and 0.1342 ± 38, and exhibit a saw-tooth HSE pattern with enriched Re and Pt. In contrast, their BMS hosts have unradiogenic 187Os/188Os of 0.1084 ± 6 and 0.1066 ± 3, with TRD ages of 2.86 and 3.09 Ga, similar to the whole-rock systematics. The metasomatic origin of the BMS is supported by (i) the highly depleted nature of the mantle peridotite and (ii) their Ni-rich sulphide assemblage. Occurrence of Pt-Fe-alloys as inclusions within BMS grains demonstrates the genetic link between the BMS and Pt-Fe-alloys and argues for formation during a single but continuous event of silicate melt

  9. 'Wiggle matching' radiocarbon dates

    NARCIS (Netherlands)

    Ramsey, CB; van der Plicht, J; Weninger, B

    2001-01-01

    This paper covers three different methods of matching radiocarbon dates to the 'wiggles' of the calibration curve in those situations where the age difference between the C-14 dates is known. These methods are most often applied to tree-ring sequences. The simplest approach is to use a classical Chi

  10. Date with Death

    Institute of Scientific and Technical Information of China (English)

    郑慧敏

    2016-01-01

    Have you ever heard about a popular movie called date with an angel? It must be sweet and lovely. But have you ever imagine about dating with death? What is your feeling when you have a chance to talk with death? Excited or afraid? I believe that many people definitely do not think about this question and neither do I.

  11. Radiometric Dating in Geology.

    Science.gov (United States)

    Pankhurst, R. J.

    1980-01-01

    Described are several aspects and methods of quantitatively measuring geologic time using a constant-rate natural process of radioactive decay. Topics include half lives and decay constants, radiogenic growth, potassium-argon dating, rubidium-strontium dating, and the role of geochronology in support of geological exploration. (DS)

  12. Dating of cremated bones

    NARCIS (Netherlands)

    Lanting, JN; Aerts-Bijma, AT; van der Plicht, J; Boaretto, E.; Carmi, I.

    2001-01-01

    When dating unburnt bone, bone collagen, the organic fraction of the bone, is used. Collagen does not survive the heat of the cremation pyre, so dating of cremated bone has been considered impossible. Structural carbonate in the mineral fraction of the bone, however, survives the cremation process.

  13. Pests of stored dates

    Science.gov (United States)

    Dates are a major food crop across a large band of Africa and Eurasia, and to a lesser extent elsewhere. In most of its growing range, dates are threatened with infestation in the field by a complex of pests including nitidulid beetles and pyralid moths of the Subfamily Phycitinae. They are further ...

  14. 10Be dating of Neogene halite

    Science.gov (United States)

    Belmaker, Reuven; Lazar, Boaz; Beer, Jürg; Christl, Marcus; Tepelyakov, Natalya; Stein, Mordechai

    2013-12-01

    Direct radioactive dating of ancient halite formations is difficult because this mineral typically lacks conventionally datable material. We describe an attempt to date Neogene halite using the cosmogenic isotope 10Be (T1/2 = 1.39 Ma). We dated marine-derived salt deposits from the Sedom and Amora (The Hebrew forms of Sodom and Gomorrah) Formations, Dead Sea basin, Israel. To verify whether Be is incorporated into marine halite we measured the stable isotope 9Be, 7Be (the short lived “cosmogenic brother” of 10Be having T1/2 = 53.3 d), and 10Be in evaporation pans of sea-salt production plants. The data suggest that seawater beryllium is incorporated into the halite with a halite-brine distribution coefficient, (KD) of about unity. A 10Be/9Be decay curve constructed for Sedom Formation halite yielded an age that lies in the range of ∼2-6 Ma. The 10Be decay curve constructed for Sedom Formation halite yielded an age that lies in the range of 3-5 Ma. This age is consistent with previous estimates of the Sedom Formation age. Furthermore, this age lies in the same range of 10Be in situ ages obtained on the lacustrine Erq El Ahmer Formation located in the northern Jordan Valley. This may imply that during the Mid Pliocene the Sedom Lagoon, the water-body that deposited the Sedom Formation, might have been already disconnected from the open sea.

  15. Osmium isotope evidence for a crustal origin of platinum group elements in the Sudbury nickel ore, Ontario, Canada

    Science.gov (United States)

    Dickin, A. P.; Richardson, J. M.; Crocket, J. H.; McNutt, R. H.; Peredery, W. V.

    1992-09-01

    Sulphide ores from the International Nickel Company's (INCO) Creighton Mine, Sudbury, were analysed for osmium isotope ratios by ICP-MS. Rhenium and osmium abundances were determined by isotope dilution using a mixed spike in solid solution in a nickel sulphide matrix. Calculated initial 187Os /188Os ratios at 1.85 Ga (the emplacement age of the Sudbury complex) cluster around 0.60. The occurrence of less radiogenic compositions is attributed to post-emplacement, open-system behaviour of the Re/Os system. The Creighton results strongly overlap the initial ratios of published osmium data from two other Sudbury mines, suggesting a narrow range of isotope ratio in the original ore, within the range of estimated osmium isotope compositions in the country rock at 1.85 Ga, using published and new data. Therefore, the sulphide ores of the Sudbury complex can have an entirely crustal source without a mantle-derived contribution. This conclusion is consistent with published neodymium isotope data for the complex and supports the meteorite impact hypothesis, since this is the most effective means of fusing the large quantity of crustal rocks necessary to generate the complex. The extraction of platinum group elements (PGE) from this silicate melt by a nickel sulphide liquid was probably analogous to the laboratory fire assay procedure.

  16. NAIP 2014 Image Dates

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — This map is produced by the Aerial Phtography Field Office (APFO) to show the image acquisition dates for the 2014 National Agriculture Imagery Program (NAIP)...

  17. NAIP 2012 Image Dates

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — This map is produced by the Aerial Phtography Field Office (APFO) to show the image acquisition dates for the 2012 National Agriculture Imagery Program (NAIP)...

  18. Expiration Dates Matter

    Medline Plus

    Full Text Available ... Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products For Consumers Home For Consumers Consumer Updates Expiration Dates Matter ... Should Know CDER FOIA Electronic Reading Room Related Consumer Updates How to Dispose of Unused Medicines Identifying ...

  19. Expiration Dates Matter

    Medline Plus

    Full Text Available ... video, FDA Pharmacist Ilisa Bernstein explains how expiration dates help determine if medicine is safe to use and will work as intended. ... Lock it Up: Medicine Safety in Your Home Giving Medicine to ...

  20. Constraints on mantle evolution from 187Os/ 188Os isotopic compositions of Archean ultramafic rocks from southern West Greenland (3.8 Ga) and Western Australia (3.46 Ga)

    Science.gov (United States)

    Bennett, Victoria C.; Nutman, Allen P.; Esat, Tezer M.

    2002-07-01

    Initial 187Os/ 188Os isotopic compositions for geochronologically and geologically well -constrained 3.8-Ga spinel peridotites from the Itsaq Gneiss Complex of southern West Greenland and chromite separates from 3.46-Ga komatiites from the Pilbara region of Western Australia have been determined to investigate the osmium isotopic evolution of the early terrestrial mantle. The measured compositions of 187Os/ 188Os(0) = 0.10262 ± 2, from an olivine separate, and 0.10329 ± 3, for a spinel separate from ˜3.8-Ga peridotite G93/42, are the lowest yet reported from any terrestrial sample. The corrections for in situ decay over 3.8 Ga for these low Re/Os phases are minimal and change the isotopic compositions by only 0.5 and 2.2% for the spinel and the olivine, respectively, resulting in 187Os/ 188Os (3.8 Ga) = 0.1021 ± 0.0002 and 0.1009 ± 0.0002, respectively. These data extend direct measurement of Os isotopic compositions to much earlier periods of Earth history than previously documented and provide the best constraints on the Os isotopic composition of the early Archean terrestrial mantle. Analyses of Pilbara chromites yield 3.46-Ga mantle compositions of 0.1042 ± 0.0002 and 0.1051 ± 0.0002. These new data, combined with published initial Os isotopic compositions from late Archean and early Proterozoic samples, are compatible with the mantle, or at least portions of it, evolving from a solar system initially defined by meteorites to a modern composition of 187Os/ 188Os(0) = 0.1296 ± 0.0008 as previously suggested from peridotite xenolith data ( Meisel et al., 2001); the associated 187Re/ 188Os(0) = 0.435 ± 0.005. Thus, chondritic 187Os/ 188Os compositions were a feature of the upper mantle for at least 3.8 billion years, requiring chondritic Re/Os ratios to have been a characteristic of the very early terrestrial mantle. In contrast, nonchondritic initial compositions of some Archean komatiites demonstrate that Os isotopic heterogeneity is an ancient feature

  1. Beneficial uses and production of isotopes

    CERN Document Server

    2001-01-01

    Isotopes, radioactive and stable, are used worldwide in various applications related to medical diagnosis or care, industry and scientific research. More than fifty countries have isotope production or separation facilities operated for domestic supply, and sometimes for international markets. This publication provides up-to-date information on the current status of, and trends in, isotope uses and production. It also presents key issues, conclusions and recommendations, which will be of interest to policy makers in governmental bodies, scientists and industrial actors in the field.

  2. A Blind Date

    Institute of Scientific and Technical Information of China (English)

    周立

    2003-01-01

    英语对话:A: Talking about girls, I still remember my first time to meet my girlfriend. Iwas so clumsy and very nervous.B: That’s the same case with me. I had the jitters at my blind date, too.A: Did you also meet your girlfriend at a blind date?B: Yeah. I was actually very shy of speaking to girls, you know?

  3. Isotopes a very short introduction

    CERN Document Server

    Ellam, Rob

    2016-01-01

    An isotope is a variant form of a chemical element, containing a different number of neutrons in its nucleus. Most elements exist as several isotopes. Many are stable while others are radioactive, and some may only exist fleetingly before decaying into other elements. In this Very Short Introduction, Rob Ellam explains how isotopes have proved enormously important across all the sciences and in archaeology. Radioactive isotopes may be familiar from their use in nuclear weapons, nuclear power, and in medicine, as well as in carbon dating. They have been central to establishing the age of the Earth and the origins of the solar system. Combining previous and new research, Ellam provides an overview of the nature of stable and radioactive isotopes, and considers their wide range of modern applications. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subjec...

  4. Dating fossil opal phytoliths

    Energy Technology Data Exchange (ETDEWEB)

    Lentfer, C.; Boyd, B. [Southern Cross University, Lismore, NSW (Australia). School of Resource Science and Management; Torrence, R. [Australian Museum, Sydney, NSW (Australia). Division of Anthropology

    1999-11-01

    Full text: Opal phytoliths are microscopic silica bodies formed by the precipitation of hydrated silica dioxide (SiO{sub 2}nH{sub 2}0) in, around and between cell walls. They are relatively resistant to degradation in most environments and thus, can occur in large quantities in palaeosediments. Consequently, they are valuable tools for environmental reconstruction. Furthermore, phytoliths are often the only recoverable organic material in well oxidised sediments, the occluded carbon provides the opportunity for dating sediment whose ages have previously been difficult to determine, and thus, increase the potential for fine resolution determination of environmental change. This poster describes the results of an investigation assessing the viability of AMS radiocarbon dating of fossil phytolith inclusions using samples from Garua Island, West New Britain, PNG. Thirteen phytolith samples, isolated from sediments previously dated using tephrastratigraphy and C14 dating of macroremains of nutshells and wood charcoal, were used in the analysis. As a control measure, thirteen parallel samples of microscopic charcoal were also dated using AMS. The results show that the AMS dates for the microscopic charcoal samples are consistent with ages anticipated from the other dating methods, for all but one sample. However, the dates for eight of the thirteen phytolith samples are considerably younger than expected. This bias could be explained by several factors, including downwashing of phytolith through soils, bioturbation, carbon exchange through the siliceous matrix of the phytolith bodies, and contamination from extraneous sources of modern carbon retained in the samples. Research is currently focusing on the investigation of these issues and selected samples are in the process of being retreated with strong oxidising agents to clear contaminants prior to re-dating. Further to this, a full investigation of one profile with a long sequence is underway. High concentrations of

  5. 76 FR 77831 - 2012 Presidential Candidate Matching Fund Submission Dates and Post Date of Ineligibility Dates...

    Science.gov (United States)

    2011-12-14

    ... 2012 Presidential Candidate Matching Fund Submission Dates and Post Date of Ineligibility Dates To...: Notice of matching fund submission dates and submission dates for statements of net outstanding campaign... fund submission dates for publicly funded 2012 presidential primary candidates. Eligible candidates...

  6. Isotope Geochronology: Technique and Application%同位素地质年龄测定技术及应用

    Institute of Scientific and Technical Information of China (English)

    陈文; 万渝生; 李华芹; 张宗清; 戴檀谟; 施泽恩; 孙敬博

    2011-01-01

    了困扰,有时不能给出正确可信的年龄.⑤Re-Os法:是目前能够直接测定金属矿床矿化年龄的唯一成熟方法.但在实验技术和应用方面还存在不少问题:a.近年来发现有些金属矿床辉钼矿的Re-Os年龄高于其赋矿围岩的年龄,原因不明;b.黄铁矿等多数硫化物矿物含Re量很低,并含有一定程度的普通Os,对样品化学制备过程中低本底的要求很高,一般实验室难以达到,普通Os也难以准确扣除;c.后期的热液活动有时可以使Os同位素发生重置,因此,金属硫化物Re-Os同位素体系封闭温度及其影响因素是一个亟待解决的问题.⑥(U-Th)/He法:(U-Th)/He同位素系统的优势是其封闭温度是已有同位素体系中最低的,能够记录地质体经历较低温度范围的时代与温度信息.该方法在矿床年代学研究中也具有可观应用前景.其不足之处是因为封闭温度很低,在用于地质体定年时要特别关注冷却速率和再加热作用的影响.%Isotope geochronology is a newly developed interdisciplinary science which combines geoscience, physics, chemistry and technical sciences, and is a young and energetic branch of earth science. The decay of radioactive isotopes is used to determine the formation age of geological body and the age of geological events, with aiming to study the formation history and evolution of earth and planetary materials. This paper presents brief introduction and summary of relative high-precise isotope dating methods in terms of theory, experiment techniques, application scope, precautions for use, in hope of providing a useful reference to geologist. Main isotope dating methods involved s are U-Pb, Ar-Ar, Rb-Sr, Sm-Nd, Re-Os and (U-Th)/He methods. (l)U-Pb method: It is one of the earliest radioactive methods for determination of geological age as well as the most important isotope dating method in China so far. In the past 10 years, the introduction of zircon U-Pb dating technique

  7. Understanding Teen Dating Violence

    Science.gov (United States)

    ... problem by gathering and studying data. Step 2: Identify risk and protective factors It is not enough to ... DM, Breiding M. Beyond correlates: A review of risk and protective factors for adolescent dating violence perpetration. Journal of Youth and Adolescence 2013; 42:633-649. ...

  8. Expiration Dates Matter

    Medline Plus

    Full Text Available ... Updates Expiration Dates Matter Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Get Consumer Updates by E-mail | ... Updates RSS Feed If your medicine has expired, it may not provide the treatment you need. In ...

  9. Earth Processes: Reading the Isotopic Code

    Science.gov (United States)

    Basu, Asish; Hart, Stan

    Publication of this monograph will coincide, to a precision of a few per mil, with the centenary of Henri Becquerel's discovery of "radiations actives" (C. R. Acad. Sci., Feb. 24, 1896). In 1896 the Earth was only 40 million years old according to Lord Kelvin. Eleven years later, Boltwood had pushed the Earth's age past 2000 million years, based on the first U/Pb chemical dating results. In exciting progression came discovery of isotopes by J. J. Thomson in 1912, invention of the mass spectrometer by Dempster (1918) and Aston (1919), the first measurement of the isotopic composition of Pb (Aston, 1927) and the final approach, using Pb-Pb isotopic dating, to the correct age of the Earth: close—2.9 Ga (Gerling, 1942), closer—3.0 Ga (Holmes, 1949) and closest—4.50 Ga (Patterson, Tilton and Inghram, 1953).

  10. Conversion of K-Ar dates with modern constants : implications for recalculation of dates reported in Kawano and Ueda using constants reported by Steiger and Jager

    OpenAIRE

    Iwata, Naoyoshi

    2013-01-01

    This report describes details of a procedure used to convert from K-Ar dates with old constants reported in the relevant literature to K-Ar dates with modern decay constants and the isotopic ratio of potassium reported by Steiger and Jager. Nearly 300 K-Ar dates published by Kawano and Ueda in the 1960s have been recalculated using this procedure. These data are useful for comparing dates reported by Kawano and Ueda to recently obtained K-Ar dates reported by others.

  11. Amino acid racemisation dating

    Energy Technology Data Exchange (ETDEWEB)

    Murray-Wallace, C.V. [University of Wollongong, Wollongong, NSW (Australia). School of Geosciences

    1999-11-01

    The potential of the time-dependent amino acid racemisation reaction as a method of age assessment was first reported by Hare and Abelson (1968). They noted that in specimens of the bivalve mollusc Mercenaria sp., greater concentrations of amino acids in the D-configuration with increasing fossil age. Hare and Abelson (1968) also reported negligible racemisation in a modern specimen of Mecanaria sp. On this basis they suggested that the extent of amino acid racemisation (epimerisation in the case of isoleucine) may be used to assess the age of materials within and beyond the range of radiocarbon dating. For the past thirty years amino acid racemisation has been extensively applied in Quaternary research as a method of relative and numeric dating, and a particularly large literature has emerged on the subject 12 refs.

  12. Dating fractures in infants

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, K.E., E-mail: kath.halliday@nuh.nhs.uk [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Broderick, N.J.; Somers, J.M. [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Hawkes, R. [Department of Radiology, Paul O' Gorman Building, Bristol (United Kingdom)

    2011-11-15

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  13. Truly Blind Dating

    Institute of Scientific and Technical Information of China (English)

    LI LI

    2010-01-01

    @@ Compared to parties,bars and nightclubs,in many countries parks are a site for family leisure and recreation and not a spot to find a date.It is not the case in China.Spouse-hunting fairs in big city parks organized by parents eager to see their children tie the knot have made parks in China a haven for relationshiphunters and their parents.

  14. What's the date of

    Institute of Scientific and Technical Information of China (English)

    刘京西

    2009-01-01

    @@ A:What's the date of our final examination? B:I'm not sure.I'll have to look it up.I'll let youknow tomorrow. A:Thank you. A:我们期末考试是哪一天? B:我也说不清.我给你查查,明天告诉你. A:谢谢你.

  15. Sediment dating in review

    Energy Technology Data Exchange (ETDEWEB)

    Prescott, J.R.; Robertson, G.B. [Adelaide Univ., SA (Australia). Dept. of Mathematical Physics

    1997-12-31

    The paper will comment on a few issues of particular relevance to Australasia. Thermoluminescent (TL) methods applied to open sites have been demonstrated to be effective. A particularly good example of this is to be found in the South East of South Australia, where a sequence of low ranges runs roughly parallel with the coast. They represent relict sand dunes left behind, on a slowly rising land surface by successive interglacial incursions of the sea at roughly 120 ka intervals. Comparison with ages established on independent geological grounds allows a test of quartz TL and IRSL ages that is believable back to 500 ka. Older than this, we do not yet understand the physics of the quartz well enough to go unequivocally forward (backward?). Similar results are emerging elsewhere. With dating limits being pushed ever further back, the time variation of the environmental radiation giving rise to the stored luminescent energy needs to be addressed. Particularly at wet sites, radioactive disequilibrium must be considered. In any case, a time profile of the radiation dose rate needs to be determined.In dating a given site or sites the value of ages obtained by any dating method,including C-14, is enhanced by parallel measurements with an different method. Paper no. 10; extended abstract. 6 refs.

  16. Date and Time

    Institute of Scientific and Technical Information of China (English)

    ZhangJingxian

    1996-01-01

    Nowadays the pace of social life is very fast.TO make clear date and time is very important to everyone,especially those who are away fromhome.You need to learn ways to express date and time in Chinese.Otherwise how can you make arrangements with your Chinese friends?41.请问,今天(是)几号?Qǐngwèn,jīntiān(shǐ)jǐ hào?(May I ask,what is the date today?)In Chinese,jǐntiān.míngtiān,hòutiān and dàhòutiān are used to express today,tomorrow,the day after tomorrow,and the fourth day fromnow.jǐ(how many)is a character used in questioning the number from two to nine.If one asks the number above nine,then shí(ten),bǎi

  17. Stable isotope studies

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  18. Dating Violence among College Students

    Science.gov (United States)

    Iconis, Rosemary

    2013-01-01

    Dating violence is a significant problem on college campuses. More than one-fifth of the undergraduate dating population are physically abused by their dating partners and an even greater percentage are psychologically abused. Researchers have identified risk factors for college student dating violence. Preventive interventions are strongly…

  19. 210Pb dating

    Science.gov (United States)

    Swarzenski, Peter W.

    2014-01-01

    Roughly fifty years ago, a small group of scientists from Belgium and the United States, trying to better constrain ice sheet accumulation rates, attempted to apply what was then know about environmental lead as a potential geochronometer. Thus Goldberg (1963) developed the first principles of the 210Pb dating method, which was soon followed by a paper by Crozaz et al. (1964), who examined accumulation history of Antarctic snow using 210Pb. Shortly thereafter, Koide et al. (1972, 1973) adapted this technique to unravel sediment deposition and accumulation records in deep-sea environments. Serendipitously, they chose to work in a deep basin off California, where an independent and robust age model had already been developed. Krishanswami et al. (1971) extended the use of this technique to lacustrine deposits to reconstruct depositional histories of lake sediment, and maybe more importantly, contaminant inputs and burial. Thus, the powerful tool for dating recent (up to about one century old) sediment deposits was established and soon widely adopted. Today almost all oceanographic or limnologic studies that address recent depositional reconstructions employ 210Pb as one of several possible geochronometers (Andrews et al., 2009; Gale, 2009; Baskaran, 2011; Persson and Helms, 2011). This paper presents a short overview of the principles of 210Pb dating and provides a few examples that illustrate the utility of this tracer in contrasting depositional systems. Potential caveats and uncertainties (Appleby et al., 1986; Binford, 1990; Binford et al., 1993; Smith, 2001; Hancock et al., 2002) inherent to the use and interpretation of 210Pb-derived age-models are also introduced. Recommendations as to best practices for most reliable uses and reporting are presented in the summary.

  20. Vulcanism and Radiocarbon Dates

    Science.gov (United States)

    Libby, L. M.; Libby, W. F.

    1972-10-01

    We consider whether the long term perturbation of radiocarbon dates, which is known to be approximately a sin function of period about 8000 years and amplitude of about 8% peak-to-peak, could have been caused in any major part by vulcanism. We conclude that this is not the case. On the contrary, present day volcanoes are a far less important source of inert CO{sub 2} (about 100 fold less) than is man's burning of fossil fuels which has caused the Suess dilution of about 2%. (auth)

  1. Flirting in Online Dating

    DEFF Research Database (Denmark)

    Mortensen, Kristine Køhler

    2017-01-01

    Various fields have examined the activity of flirting, predominantly based on experimental and reported data; the interactional workings are therefore often overlooked. Based on emails and chats from two Danish online dating sites, this article investigates how users negotiate romantic connections...... through the flirting strategy of ‘imagined togetherness’, linguistically constructing imagery of a shared future. Using the notion of the chronotope (Bakhtin 1981), turn-by-turn analysis demonstrates how users, embedded in the activity of getting to know each other, tenuously communicate romantic interest...... by alluding to future points at which they might be together. Central to the strategy is a sequential pattern of avoiding closure and thereby preserving the imagery’s implicitness. The article concludes by arguing that while imagined togetherness functions a way of probing interests and thus protecting...

  2. Osmium isotope constraints on the proportion of bolide component in Chicxulub impact melt rocks

    Science.gov (United States)

    Gelinas, A.; Kring, D. A.; Zurcher, L.; Urrutia-Fucugauchi, J.; Morton, O.; Walker, R. J.

    2004-06-01

    The spatial distribution and amount of material transferred from the bolide involved in the Cretaceous/Tertiary (K/T) event to the target rocks at Chicxulub is still poorly constrained. In this study, Re-Os isotopic analyses of impact melt breccias and lithic clasts from the Yaxcopoil-1 (Yax-1) borehole were used to determine the distribution and proportion of the bolide component in the target rocks. Because of the much greater concentration of Os in chondritic meteorites compared to the target rocks, little addition of the bolide component would be necessary to greatly perturb the Os concentration and isotopic composition of target rocks. Hence, this is a very sensitive means of examining bolide contributions to the target rocks. For the examined suite of samples, the initial 187Os/188Os ratios vary from 0.19 to 2.3. Conservative mixing calculations suggest that the bolide component comprised as much as approximately 0.1%, by mass, of some samples. Most samples, however, have negligible contributions from the bolide. No samples have Os that is dominated by the bolide component, so for this suite of samples, it is impossible to fingerprint the chemical nature of the bolide using relative abundances of siderophile elements. These results suggest that the bolide did not contribute a significant amount of material to the target rocks. This may, in turn, indicate that most of the bolide was vaporized upon impact or otherwise ejected without mixing with the melt from the target.

  3. Radiocarbon dating of Mesolithic pottery from Northern Germany

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    The earliest pottery in Schleswig-Holstein, Northern Germany, was produced by the Final Mesolithic Ertebølle culture. Radiocarbon dating of food crusts on Ertebølle pottery indicated that ceramics from inland sites were substantially older than those from the coast. Therefore, a freshwater...... of magnitude and the degree of variability of the freshwater reservoir effect in Schleswig-Holstein. Experiments with copies of Ertebølle vessels yielded reference material for radiocarbon dating and stable isotope analysis. Food crusts, terrestrial samples and fishbones from two Ertebølle inland sites were...... analysed as well. It could be shown that the inland pottery most probably has the same age as the coastal pottery. Furthermore, I will present some methodological considerations about pottery dating and a pilot study where food crusts as well as total lipid extracts were dated....

  4. The discovery of isotopes a complete compilation

    CERN Document Server

    Thoennessen, Michael

    2016-01-01

    This book describes the exciting discovery of every isotope observed on earth to date, which currently numbers some 3000. For each isotope a short essay highlights the authors of the first publication for the isotope, the laboratory and year where and when the isotope was discovered, as well as details about the production and detection methods used. In controversial cases previously claims are also discussed. At the end a comprehensive table lists all isotopes sorted by elements and a complete list of references. Preliminary versions of these paragraphs have been published over the last few years as separate articles in the journal "Atomic Data and Nuclear Data Tables". The work re-evaluates all assignments judging them with a uniform set of criteria. In addition, the author includes over 100 new isotopes which have been discovered since the articles published. This book is a source of information for researchers as well as enthusiastic laymen alike. From the prepublication review: “The explanations focus ...

  5. Violence in Adolescent Dating Relationships

    Science.gov (United States)

    Jouriles, Ernest N.; Platt, Cora; McDonald, Renee

    2009-01-01

    Beginning with a definition of dating and dating violence among adolescents, this article explores the factors which impact such violence. It concludes with a review of two school-based prevention/intervention programs (Safe Dates and The Youth Relationships Project). (Contains 1 table.)

  6. METHOD OF ISOTOPE CONCENTRATION

    Science.gov (United States)

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  7. Os and U-Th isotope signatures of arc magmatism near Mount Mazama, Crater Lake, Oregon

    Science.gov (United States)

    Ankney, Meagan E.; Shirey, Steven B.; Hart, Garret L.; Bacon, Charles R.; Johnson, Clark M.

    2016-03-01

    Interaction of mantle melts with the continental crust can have significant effects on the composition of the resulting melts as well as on the crust itself, and tracing this interaction is key to our understanding of arc magmatism. Lava flows and pyroclastic deposits erupted from ∼50 to 7.7 ka at Mt. Mazama (Crater Lake, Oregon) were analyzed for their Re/Os and U-Th isotopic compositions. Mafic lavas from monogenetic vents around Mt. Mazama that erupted during the buildup to its climactic eruption have lower 187Os/188Os ratios (0.1394 to 0.1956) and high 230Th excess ((230Th/238U)0 of 1.180 to 1.302), whereas dacites and rhyodacites tend to have higher 187Os/188Os ratios (0.2292 to 0.2788) and significant 238U excess ((230Th/238U)0 of 0.975 to 0.989). The less radiogenic Os isotope compositions of the mafic lavas can be modeled by assimilation of young (∼2.5 to 7 Ma), mafic lower crust that was modified during regional extension, whereas the more radiogenic Os isotope compositions of the dacites and rhyodacites can be attributed to assimilation of older (∼10 to 16 Ma), mid to upper crust that acquired its composition during an earlier period of Cascade magmatism. Production of Th excesses in the lower crust requires very young garnet formation accompanying dehydration melting in the lower crust at less than a few 100 ka by heat from recent basaltic magma injection. The results from this study suggest that the combination of Os and Th isotopes may be used to provide insights into the timescales of evolution of the continental crust in arc settings, as well as the influence of the crust on erupted magmas, and suggest a link between the age and composition of the lower and upper crust to regional tectonic extension and/or earlier Cascade magmatism.

  8. Chromium isotope fractionation during oxidative weathering of the Antrim Basalts: An insight into the global Cr geochemical cycle

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary; Døssing, Lasse Nørbye; Frei, Robert

    Cr isotopes fractionate during oxidative weathering of the continents; the oxidation of Cr (III) bearing minerals produces soluble Cr (VI) which is enriched in the heavy isotope, Cr (VI) is lost to local rivers resulting in a Cr depleted, isotopically light residual soil [1] [2]. To date, researc...

  9. Thermoluminescence dating of flint

    Science.gov (United States)

    Valladas, H.

    Our ancestors have been making flint tools for over a million years. The tools or the flakes left by the flint-knappers have become important markers of prehistoric habitats. The imperishable and ubiquitous nature of flint explains why generations of prehistorians have used it to build a stone age chronology. To be dateable by TL flint must be heated to at least 450°C. While human use of fire may be as old as half a million years, the first true hearths appear late during the Lower Paleolithic period. At Terra-Amata, one of the oldest hearths discovered in France was dated to 230 ± 40 ka BP by Wintle and Aitken (1977). By the dawn of the Middle Paleolithic fire must have become fully domesticated, judging by the accumulations of charred debris that henceforth litter human habitats. For example, at the Middle Paleolithic site of Kebara the profusion of hearths is vividly illustrated by numerous superposed white ash and black charcoal layers extending to a depth of 4 m (Meignen et al., 1989).

  10. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a m

  11. Identification of isotopically primitive interplanetary dust particles: A NanoSIMS isotopic imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Floss, C; Stadermann, F J; Bradley, J P; Dai, Z R; Bajt, S; Graham, G; Lea, A S

    2005-09-02

    We have carried out a comprehensive survey of the isotopic compositions (H, B, C, N, O, S) of a suite of interplanetary dust particles (IDPs), including both cluster and individual particles. Isotopic imaging with the NanoSIMS shows the presence of numerous discrete hotspots that are strongly enriched in {sup 15}N, including the largest {sup 15}N enrichments ({approx}1300 {per_thousand}) observed in IDPs to date. A number of the IDPs also contain larger regions with more modest enrichments in {sup 15}N, leading to average bulk N isotopic compositions that are {sup 15}N-enriched in these IDPs. Although C isotopic compositions are normal in most of the IDPs, two {sup 15}N-rich N-hotspots have correlated {sup 13}C anomalies. CN{sup -}/C{sup -} ratios suggest that most of the {sup 15}N-rich hotspots are associated with relatively N-poor carbonaceous matter, although specific carriers have not been determined. H isotopic distributions are similar to those of N: D anomalies are present both as distinct very D-rich hotspots and as larger regions with more modest enrichments. Nevertheless, H and N isotopic anomalies are not directly correlated, consistent with results from previous studies. Oxygen isotopic imaging shows the presence of abundant presolar silicate grains in the IDPs. The O isotopic compositions of the grains are similar to those found in presolar oxide and silicate grains from primitive meteorites. Most of the silicate grains in the IDPs have isotopic ratios consistent with meteoritic Group 1 oxide grains, indicating origins in oxygen-rich red giant and asymptotic giant branch stars, but several presolar silicates exhibit the {sup 17}O and {sup 18}O enrichments of Group 4 oxide grains, whose origin is less well understood. Based on their N isotopic compositions, the IDPs studied here can be divided into two groups. One group is characterized as being ''isotopically primitive'' and consists of those IDPs that have anomalous bulk N isotopic

  12. Zinc isotope fractionation during magmatic differentiation and the isotopic composition of the bulk Earth

    Science.gov (United States)

    Chen, Heng; Savage, Paul S.; Teng, Fang-Zehn; Helz, Rosalind T.; Moynier, Frédéric

    2013-01-01

    he zinc stable isotope system has been successfully applied to many and varied fields in geochemistry, but to date it is still not completely clear how this isotope system is affected by igneous processes. In order to evaluate the potential application of Zn isotopes as a proxy for planetary differentiation and volatile history, it is important to constrain the magnitude of Zn isotopic fractionation induced by magmatic differentiation. In this study we present high-precision Zn isotope analyses of two sets of chemically diverse, cogenetic samples from Kilauea Iki lava lake, Hawaii, and Hekla volcano, Iceland, which both show clear evidence of having undergone variable and significant degrees of magmatic differentiation. The Kilauea Iki samples display small but resolvable variations in Zn isotope composition (0.26‰66Zn66Zn defined as the per mille deviation of a sample's 66Zn/64Zn compositional ratio from the JMC-Lyon standard), with the most differentiated lithologies exhibiting more positive δ66Zn values. This fractionation is likely a result of the crystallization of olivine and/or Fe–Ti oxides, which can both host Zn in their crystal structures. Samples from Hekla have a similar range of isotopic variation (0.22‰66Zn66Zn=0.28±0.05‰ (2s.d.).

  13. Target rocks, impact glasses, and melt rocks from the Lonar crater, India: Highly siderophile element systematics and Sr-Nd-Os isotopic signatures

    Science.gov (United States)

    Schulz, Toni; Luguet, Ambre; Wegner, Wencke; Acken, David; Koeberl, Christian

    2016-07-01

    The Lonar crater is a ~0.57-Myr-old impact structure located in the Deccan Traps of the Indian peninsula. It probably represents the best-preserved impact structure hosted in continental flood basalts, providing unique opportunities to study processes of impact cratering in basaltic targets. Here we present highly siderophile element (HSE) abundances and Sr-Nd and Os isotope data for target basalts and impactites (impact glasses and impact melt rocks) from the Lonar area. These tools may enable us to better constrain the interplay of a variety of impact-related processes such as mixing, volatilization, and contamination. Strontium and Nd isotopic compositions of impactites confirm and extend earlier suggestions about the incorporation of ancient basement rocks in Lonar impactites. In the Re-Os isochron plot, target basalts exhibit considerable scatter around a 65.6 Myr Re-Os reference isochron, most likely reflecting weathering and/or magma replenishment processes. Most impactites plot at distinctly lower 187Re/188Os and 187Os/188Os ratios compared to the target rocks and exhibit up to two orders of magnitude higher abundances of Ir, Os, and Ru. Moreover, the impactites show near-chondritic interelement ratios of HSE. We interpret our results in terms of an addition of up to 0.03% of a chondritc component to most impact glasses and impact melt rocks. The magnitude of the admixture is significantly lower than the earlier reported 12-20 wt% of extraterrestrial component for Lonar impact spherules, reflecting the typical difference in the distribution of projectile component between impact glass spherules and bulk impactites.

  14. Generation of Radixenon Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    McIntyre, Justin I.; Bowyer, Ted W.; Hayes, James C.; Heimbigner, Tom R.; Morris, Scott J.; Panisko, Mark E.; Pitts, W. K.; Pratt, Sharon L.; Reeder, Paul L.; Thomas, Charles W.

    2003-06-30

    Pacific Northwest National Laboratory has developed an automated system for separating Xe from air and can detect the following radioxenon isotopes, 131mXe, 133mXe, 133Xe, and 135Xe. This report details the techniques used to generate the various radioxenon isotopes that are used for the calibration of the detector as well as other isotopes that have the potential to interfere with the fission produced radioxenon isotopes. Fission production is covered first using highly enriched uranium followed by a description and results from an experiment to produce radioxenon isotopes from neutron activation of ambient xenon.

  15. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  16. Dating mortars: three medieval Spanish architectures

    Directory of Open Access Journals (Sweden)

    Quirós Castillo, Juan Antonio

    2011-12-01

    Full Text Available One of the major issues in building archaeology is finding the age of elements and structures discovered. Mortars represent a class of material basically constituted by a mixture of different phases (i.e. binder, aggregates, water and are widely used for constructive uses and artworks. Current scientific literature regarding the possibility of accurate radiocarbon dating for mortars reports different and still contradictory results. In this study, a new protocol for radiocarbon dating of mortar developed at the Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE is used to perform 14C measurements on archaeological mortars coming from three medieval architectures of northern Spain (two churches and the walls of a castle. Results observed will be discussed and compared with independent age estimations (i.e. radiocarbon dating performed on organic materials found in the same study site, archaeological analyses in order to frame experimental observations in the actual site knowledge by means of a multidisciplinary approach.Una de las principales problemáticas a las que se enfrenta la arqueología de la arquitectura es datar los elementos y las estructuras. Las argamasas son un tipo de material constituido por una mezcla de diferentes elementos (agregados, agua y empleadas en muchos tipos de construcciones. Los estudios realizados hasta la actualidad en torno a la posibilidad de realizar dataciones radiocarbónicas precisas han proporcionado resultados contradictorios. El objetivo de este artículo es el de presentar un nuevo protocolo para datar la arquitectura histórica desarrollado por el Centre for Isotopic Research on Cultural and Enviromental Heritage (CIRCE, basado en la realización de dataciones radiocarbónicas de argamasas a partir del análisis de tres arquitecturas medievales del norte del España, dos iglesias y la muralla de un castillo. Los resultados obtenidos han sido confrontados y comparados con otros

  17. Iron isotope biogeochemistry of Neoproterozoic marine shales

    Science.gov (United States)

    Kunzmann, Marcus; Gibson, Timothy M.; Halverson, Galen P.; Hodgskiss, Malcolm S. W.; Bui, Thi Hao; Carozza, David A.; Sperling, Erik A.; Poirier, André; Cox, Grant M.; Wing, Boswell A.

    2017-07-01

    Iron isotopes have been widely applied to investigate the redox evolution of Earth's surface environments. However, it is still unclear whether iron cycling in the water column or during diagenesis represents the major control on the iron isotope composition of sediments and sedimentary rocks. Interpretation of isotopic data in terms of oceanic redox conditions is only possible if water column processes dominate the isotopic composition, whereas redox interpretations are less straightforward if diagenetic iron cycling controls the isotopic composition. In the latter scenario, iron isotope data is more directly related to microbial processes such as dissimilatory iron reduction. Here we present bulk rock iron isotope data from late Proterozoic marine shales from Svalbard, northwestern Canada, and Siberia, to better understand the controls on iron isotope fractionation in late Proterozoic marine environments. Bulk shales span a δ 56Fe range from -0.45 ‰ to +1.04 ‰ . Although δ 56Fe values show significant variation within individual stratigraphic units, their mean value is closer to that of bulk crust and hydrothermal iron in samples post-dating the ca. 717-660 Ma Sturtian glaciation compared to older samples. After correcting for the highly reactive iron content in our samples based on iron speciation data, more than 90% of the calculated δ 56Fe compositions of highly reactive iron falls in the range from ca. -0.8 ‰ to +3 ‰ . An isotope mass-balance model indicates that diagenetic iron cycling can only change the isotopic composition of highly reactive iron by oxygen levels. Alternatively, increasing oxygen levels would have led to a higher proportion of Fe(II) being oxidized, without decreasing the initial size of the ferrous seawater iron pool. We consider the latter explanation as the most likely. According to this hypothesis, the δ 56Fe record reflects the redox evolution of Earth's surface environments. δ 56Fe values in pre-Sturtian samples

  18. Os-isotopic Compositions of Peridotite Xenoliths from the Oceanic Mantle: Implications for the Age of Isotopic Domains in the Oceanic Mantle.

    Science.gov (United States)

    Jackson, M. G.; Shirey, S. B.; Hauri, E. H.; Kurz, M. D.

    2015-12-01

    Os-isotopic compositions of abyssal peridotites and peridotite xenoliths from oceanic hotpots that sample the convecting mantle extend to relatively unradiogenic compositions. However, they do not preserve a record of early-formed (Hadean and Archean) depleted mantle domains, either by earlier cycles of ridge-related depletion, continent extraction, or subcontinental lithospheric mantle erosion. The lack of preservation of early-formed (Hadean and Archean) depleted Os-isotopic compositions is consistent with the lack of preservation of Hadean 142Nd/144Nd variability in the modern convecting mantle, but is in stark contrast to the existence of early-formed (early-Hadean), heterogeneous 129Xe/130Xe isotopic anomalies in the modern mantle. Mukhopadhay (Nature, 2012) suggested that the erasure of 142Nd/144Nd, but not 129Xe/130Xe, anomalies from the convecting mantle may be due to the small magnitude of the 142Nd/144Nd anomalies (10% variability observed) because the smaller 142Nd/144Nd anomalies would have been more easily erased than the larger magnitude 129Xe/130Xe anomalies. This model does not work for the Re-Os system because the magnitude of Os-isotopic heterogeneities in the mantle are large, yet early-formed Os-isotopic signatures have been erased. For example, the 187Os/188Os of early-formed depleted mantle at 4.55 Ga was ~0.095, which is >25% lower than the modern mantle. Given that there were substantial amounts of mantle partial melting throughout the Hadean and Archean, it is hard to understand how some refractory residues retaining some vestige of these low, early-formed Os isotopic compositions have not have been preserved in the modern mantle. Therefore, the lack of preservation of early-formed, large magnitude 187Os/188Os excursions in the modern convecting mantle suggests that the preservation of early geochemical heterogeneities was not necessarily a function of the original geochemical anomaly. We explore alternative solutions to the paradox of

  19. Luminescence dating of Netherlands’ sediments

    OpenAIRE

    Wallinga, J.; Davids, F.; Dijkmans, J.W.A.

    2007-01-01

    Over the last decades luminescence dating techniques have been developed that allow earth scientists to determine the time of deposition of sediments. In this contribution we review: 1) the development of the methodology; 2) tests of the reliability of luminescence dating on Netherlands’ sediments; and 3) geological applications of the method in the Netherlands. Our review shows that optically stimulated luminescence dating of quartz grains using the single aliquot regenerative dose method yi...

  20. AMS of the Minor Plutonium Isotopes.

    Science.gov (United States)

    Steier, P; Hrnecek, E; Priller, A; Quinto, F; Srncik, M; Wallner, A; Wallner, G; Winkler, S

    2013-01-01

    VERA, the Vienna Environmental Research Accelerator, is especially equipped for the measurement of actinides, and performs a growing number of measurements on environmental samples. While AMS is not the optimum method for each particular plutonium isotope, the possibility to measure (239)Pu, (240)Pu, (241)Pu, (242)Pu and (244)Pu on the same AMS sputter target is a great simplification. We have obtained a first result on the global fallout value of (244)Pu/(239)Pu = (5.7 ± 1.0) × 10(-5) based on soil samples from Salzburg prefecture, Austria. Furthermore, we suggest using the (242)Pu/(240)Pu ratio as an estimate of the initial (241)Pu/(239)Pu ratio, which allows dating of the time of irradiation based solely on Pu isotopes. We have checked the validity of this estimate using literature data, simulations, and environmental samples from soil from the Salzburg prefecture (Austria), from the shut down Garigliano Nuclear Power Plant (Sessa Aurunca, Italy) and from the Irish Sea near the Sellafield nuclear facility. The maximum deviation of the estimated dates from the expected ages is 6 years, while relative dating of material from the same source seems to be possible with a precision of less than 2 years. Additional information carried by the minor plutonium isotopes may allow further improvements of the precision of the method.

  1. Zircon Dating,Hf Isotope Composition,Geochemistry and Their Prospecting Signification of the Langqiao Intrusion in Jingxian County,South Anhui Province%皖南泾县榔桥岩体锆石U-Pb定年、Hf同位素和地球化学特征及其找矿指示意义

    Institute of Scientific and Technical Information of China (English)

    李双; 杨晓勇; 孙卫东; 戴圣潜

    2014-01-01

    The Langqiao granodiorite intrusion is a complex pluton with melted crust-mantle materials,located in the northern margin of the fold belt in Jingxian county of South Anhui province.The U-Pb dating results for zircons from two granodiorite samples formed in main forming stage of the Langqiao intrusion and one porphyry granite samples from the vein rock formed at the later forming stage yielded weight average ages of 135. 6±1. 8Ma,137. 6 ±2. 0Ma,136. 4 ±1. 9Ma,respectively,indicating the intrusion formed in the Early Cretaceous.The zircon Hf isotopic analysis suggested that this intrusion was formed by partial melting of Mesoproterozoic crustal materials,contaminated by a small amount of Paleo-proterozoic crutal materials.The “zircon saturation temperature”calculated by whole-rock Zr contents show the magmatic crystallization temperature of Langqiao granodiorite intrusion and porphyry granite from vein rock is 749~781℃,722~745℃,respectively,indicating rapid cooling history of magma;the element geochemical studies show that the intrusion formed accompanied with fractional crystallization of plagioclase, K-feldspar and the accessory minerals,such as apatite,ilmenite.Zircon Ce(Ⅳ)/Ce(Ⅲ)ratios suggest the high oxygen fugacity in the magmatic process is conducive the Cu-Au mineralization,while the fractional crystallization of plagioclase reduced EuN/EuN* to 0. 2~0. 4 .The Langqiao intrusion is enriched in large-ion lithophile elements,Pb,depleted in high field strength elements (Nb,Ta,Zr,Ti),also has obvious differentiation between LREE and HREE,with more enriched LREE than HREE,similar to the arc magmatic rock;tectonic setting discrimination diagrams suggested the formation of Langqiao intrusion was closely related to the subduction and collision of the Paleo-pacific plate towards the Euroasian continent.%安徽泾县榔桥花岗闪长岩体为分布于皖南台褶带北缘壳幔同熔型复式岩体。该岩体主侵入期两个花岗闪长岩样品和

  2. Carbon 14 dating method; Methode de datation par le carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Fortin, Ph

    2000-07-01

    This document gives a first introduction to {sup 14}C dating as it is put into practice at the radiocarbon dating centre of Claude-Bernard university (Lyon-1 univ., Villeurbanne, France): general considerations and recalls of nuclear physics; the {sup 14}C dating method; the initial standard activity; the isotopic fractioning; the measurement of samples activity; the liquid-scintillation counters; the calibration and correction of {sup 14}C dates; the preparation of samples; the benzene synthesis; the current applications of the method. (J.S.)

  3. Luminescence dating of Netherland's sediments

    NARCIS (Netherlands)

    Wallinga, J.; Davids, F.; Dijkmans, J.W.A.

    2007-01-01

    Over the last decades luminescence dating techniques have been developed that allow earth scientists to determine the time of deposition of sediments. In this contribution we revity: 1) the development of the methodology, 2) tests of the reliability of luminescence dating on Netherlands' sediments;

  4. 75 FR 16516 - Dates Correction

    Science.gov (United States)

    2010-04-01

    ... From the Federal Register Online via the Government Publishing Office ] NATIONAL ARCHIVES AND RECORDS ADMINISTRATION Office of the Federal Register Dates Correction Correction In the Notices section... through 15499, the date at the top of each page is corrected to read ``Monday, March 29, 2010''....

  5. Isotopic evolution of Mauna Loa volcano

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, M.D.; Kammer, D.P. (Chemistry Dept., Woods Hole Oceanographic Institution, MA (USA))

    1991-04-01

    In an effort to understand the temporal helium isotopic variations in Mauna Loa volcano, we have measured helium, strontium and lead isotopes in a suite of Mauna Loa lavas that span most of the subaerial eruptive history of the volcano. The lavas range in age from historical flows to Ninole basalt which are thought to be several hundred thousand years old. Most of the samples younger than 30 ka in age (Kau Basalt) are radiocarbon-dated flows, while the samples older than 30 ka are stratigraphically controlled (Kahuku and Ninole Basalt). The data reveal a striking change in the geochemistry of the lavas approximately 10 ka before present. The lavas older than 10 ka are characterized by high {sup 3}He/{sup 4}He ({approx equal} 16-20 times atmospheric), higher {sup 206}Pb/{sup 204}Pb ({approx equal} 18.2), and lower {sup 87}Sr/{sup 86}Sr({approx equal} 0.70365) ratios than the younger Kau samples (having He, Pb and Sr ratios of approximately 8.5 x atmospheric, 18.1 and 0.70390, respectively). The historical lavas are distinct in having intermediate Sr and Pb isotopic compositions with {sup 3}He/{sup 4}He ratios similar to the other young Kau basalt ({approx equal} 8.5 x atmospheric). The isotopic variations are on a shorter time scale (100 to 10,000 years) than has previously been observed for Hawaiian volcanoes, and demonstrate the importance of geochronology and stratigraphy to geochemical studies. The data show consistency between all three isotope systems, which suggests that the variations are not related to magma chamber degassing processes, and that helium is not decoupled from the other isotopes. However, the complex temporal evolution suggests that three distinct mantle sources are required to explain the isotopic data. Most of the Mauna Loa isotopic variations could be explained by mixing between a plume type source, similar to Loihi, and an asthenospheric source with helium isotopic composition close to MORB and elevated Sr isotopic values. (orig./WL).

  6. Magnesium isotope systematics in Martian meteorites

    Science.gov (United States)

    Magna, Tomáš; Hu, Yan; Teng, Fang-Zhen; Mezger, Klaus

    2017-09-01

    Magnesium isotope compositions are reported for a suite of Martian meteorites that span the range of petrological and geochemical types recognized to date for Mars, including crustal breccia Northwest Africa (NWA) 7034. The δ26Mg values (per mil units relative to DSM-3 reference material) range from -0.32 to -0.11‰; basaltic shergottites and nakhlites lie to the heavier end of the Mg isotope range whereas olivine-phyric, olivine-orthopyroxene-phyric and lherzolitic shergottites, and chassignites have slightly lighter Mg isotope compositions, attesting to modest correlation of Mg isotopes and petrology of the samples. Slightly heavier Mg isotope compositions found for surface-related materials (NWA 7034, black glass fraction of the Tissint shergottite fall; δ26Mg > -0.17‰) indicate measurable Mg isotope difference between the Martian mantle and crust but the true extent of Mg isotope fractionation for Martian surface materials remains unconstrained. The range of δ26Mg values from -0.19 to -0.11‰ in nakhlites is most likely due to accumulation of clinopyroxene during petrogenesis rather than garnet fractionation in the source or assimilation of surface material modified at low temperatures. The rather restricted range in Mg isotope compositions between spatially and temporally distinct mantle-derived samples supports the idea of inefficient/absent major tectonic cycles on Mars, which would include plate tectonics and large-scale recycling of isotopically fractionated surface materials back into the Martian mantle. The cumulative δ26Mg value of Martian samples, which are not influenced by late-stage alteration processes and/or crust-mantle interactions, is - 0.271 ± 0.040 ‰ (2SD) and is considered to reflect δ26Mg value of the Bulk Silicate Mars. This value is robust taking into account the range of lithologies involved in this estimate. It also attests to the lack of the Mg isotope variability reported for the inner Solar System bodies at current

  7. Agricultural Origins and the Isotopic Identity of Domestication in Northern China

    National Research Council Canada - National Science Library

    Loukas Barton; Seth D. Newsome; Fa-Hu Chen; Hui Wang; Thomas P. Guilderson; Robert L. Bettinger; Frank Hole

    2009-01-01

    Stable isotope biochemistry (δ¹⁳C and δ¹⁵N) and radiocarbon dating of ancient human and animal bone document 2 distinct phases of plant and animal domestication at the Dadiwan site in northwest China...

  8. 78 FR 28652 - Advisory Committee on the Medical Uses of Isotopes: Call for Nominations

    Science.gov (United States)

    2013-05-15

    ... COMMISSION Advisory Committee on the Medical Uses of Isotopes: Call for Nominations AGENCY: U.S. Nuclear... the Medical Uses of Isotopes (ACMUI). DATES: Nominations are due on or before July 15, 2013...) nuclear cardiologist; (c) medical physicist in nuclear medicine unsealed byproduct material; (d) therapy...

  9. Environmental isotope investigation of groundwater flow in the Honey Lake Basin, California and Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Rose, T.P.; Davisson, M.L.; Hudson, G.B.; Varian, A.R.

    1997-07-01

    The hydrology of Honey Lake Basin was studied using environmental isotope measurements of approximately 130 water samples collected during 1995 and 1996. The principal analytical methods included hydrogen, oxygen and carbon stable isotope ratio measurements, radiocarbon and tritium dating, and measurements of dissolved noble gas abundances.

  10. 77 FR 64143 - Manufacturer of Controlled Substances; Notice of Registration; Cambridge Isotope Lab

    Science.gov (United States)

    2012-10-18

    ... Enforcement Administration Manufacturer of Controlled Substances; Notice of Registration; Cambridge Isotope Lab By Notice dated June 18, 2012, and published in the Federal Register on June 26, 2012, 77 FR 38086, Cambridge Isotope Lab, 50 Frontage Road, Andover, Massachusetts 01810, made application by renewal to...

  11. U-Th Burial Dates on Ostrich Eggshell

    Science.gov (United States)

    Sharp, W. D.; Fylstra, N. D.; Tryon, C. A.; Faith, J. T.; Peppe, D. J.

    2015-12-01

    Obtaining precise and accurate dates at archaeological sites beyond the range of radiocarbon dating is challenging but essential for understanding human origins. Eggshells of ratites (large flightless birds including ostrich, emu and others) are common in many archaeological sequences in Africa, Australia and elsewhere. Ancient eggshells are geochemically suitable for the U-Th technique (1), which has about ten times the range of radiocarbon dating (>500 rather than 50 ka), making eggshells attractive dating targets. Moreover, C and N isotopic studies of eggshell provide insights into paleovegetation and paleoprecipitation central to assessing past human-environment interactions (2,3). But until now, U-Th dates on ratite eggshell have not accounted for the secondary origin of essentially all of their U. We report a novel approach to U-Th dating of eggshell that explicitly accounts for secondary U uptake that begins with burial. Using ostrich eggshell (OES) from Pleistocene-Holocene east African sites, we have measured U and 232Th concentration profiles across OES by laser ablation ICP-MS. U commonly peaks at 10s to 100s of ppb and varies 10-fold or more across the ~2 mm thickness of OES, with gradients modulated by the layered structure of the eggshell. Common Th is high near the shell surfaces, but low in the middle "pallisade" layer of OES, making it optimal for U-Th dating. We determine U-Th ages along the U concentration gradient by solution ICP-MS analyses of two or more fractions of the pallisade layer. We then estimate OES burial dates using a simple model for diffusive uptake of uranium. Comparing such "U-Th burial dates" with radiocarbon dates for OES calcite from the same shells, we find good agreement in 7 out of 9 cases, consistent with rapid burial and confirming the accuracy of the approach. The remaining 2 eggshells have anomalous patterns of apparent ages that reveal they are unsuitable for U-Th dating, thereby providing reliability criteria innate

  12. Discovery of the Cobalt Isotopes

    OpenAIRE

    Szymanski, T.; Thoennessen, M.

    2009-01-01

    Twenty-six cobalt isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  13. Discovery of the Arsenic Isotopes

    CERN Document Server

    Shore, A; Heim, M; Schuh, A; Thoennessen, M

    2009-01-01

    Twenty-nine arsenic isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  14. Intracellular Cadmium Isotope Fractionation

    Science.gov (United States)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  15. Microbially Mediated Kinetic Sulfur Isotope Fractionation: Reactive Transport Modeling Benchmark

    Science.gov (United States)

    Wanner, C.; Druhan, J. L.; Cheng, Y.; Amos, R. T.; Steefel, C. I.; Ajo Franklin, J. B.

    2014-12-01

    Microbially mediated sulfate reduction is a ubiquitous process in many subsurface systems. Isotopic fractionation is characteristic of this anaerobic process, since sulfate reducing bacteria (SRB) favor the reduction of the lighter sulfate isotopologue (S32O42-) over the heavier isotopologue (S34O42-). Detection of isotopic shifts have been utilized as a proxy for the onset of sulfate reduction in subsurface systems such as oil reservoirs and aquifers undergoing uranium bioremediation. Reactive transport modeling (RTM) of kinetic sulfur isotope fractionation has been applied to field and laboratory studies. These RTM approaches employ different mathematical formulations in the representation of kinetic sulfur isotope fractionation. In order to test the various formulations, we propose a benchmark problem set for the simulation of kinetic sulfur isotope fractionation during microbially mediated sulfate reduction. The benchmark problem set is comprised of four problem levels and is based on a recent laboratory column experimental study of sulfur isotope fractionation. Pertinent processes impacting sulfur isotopic composition such as microbial sulfate reduction and dispersion are included in the problem set. To date, participating RTM codes are: CRUNCHTOPE, TOUGHREACT, MIN3P and THE GEOCHEMIST'S WORKBENCH. Preliminary results from various codes show reasonable agreement for the problem levels simulating sulfur isotope fractionation in 1D.

  16. Hydrology and isotope geochemistry; Hydrologie et geochimie isotopique

    Energy Technology Data Exchange (ETDEWEB)

    Causse, Ch.; Gasse, F

    1998-12-31

    This book gathers recent works in hydrology and isotopic geochemistry. Part I exposes the general water cycle, from precipitations to deep aquifers, through the analysis of hydrogen, oxygen and carbon isotopic composition. Regional types are laid out from high latitudes (Spitzberg), through temperate regions (Parisian Basin), to the tropics (the Soudanian-Sahelian Niger Basin). The significance of isotopic techniques for Global Change analysis in shown in part II. Several case studies, mainly in Africa, reconstruct the hydro-climatic history through the pluri-proxy analysis of sediment profiles, where isotopic geochemistry is key. The last glacial maximum cooling is shown to have been homogeneous throughout middle and low latitudes, based upon noble gases isotopic analysis in groundwaters. The interpretation of some isotopic analysis could sometimes be questionable due to the organic origin of carbon in some sedimented carbonates. Part III refers to isotopes of cosmic origin and to in situ production of radionuclides. {sup 14}C dating is reminded to have contributed to our understanding of climate change mechanisms during the last glacial and post-glacial periods. Both the limitations and the recent improvements in this methodology are highlighted in a well documented synthesis. Isotopic data enable geochemistry to be the base for modelling stability conditions in the Oklo natural fossil nuclear fission reactor. (author)

  17. Surface-Cycling of Rhenium and its Isotopes

    Science.gov (United States)

    2009-06-01

    average Mo concentration. B: Cumulative Yenisei H2O and Mo fluxes for 2004. 63 Jan 1 0.5 0 1.5 2.0 W a te r flu x, k m 3 d -1 Calendar date, 2004 2.5...and Applied Chemistry, 70: 217–235. [27, 126, 135] Russ, G. P., Bazan , J. M., and Date, A. R. (1987), Osmium isotopic ratio measure- ments by

  18. Osmium Isotopic Composition of the Sumbar Cretaceous- Tertiary Boundary, Turkmenia

    Science.gov (United States)

    Meisel, T.; Krahenbuhl, U.; Nazarov, M. A.

    1992-07-01

    Turekian (1982) propagated the use of the osmium isotopic composition as a cosmic indicator for the origin of the high osmium (and iridium) layers at the K/T boundaries. He did not consider the osmium isotopic signature of the terrestrial mantle, which also has a chondritic evolution of the Re-Os system. Osmium cannot serve alone as an infallible indicator of the impact theory, but interesting results can be obtained from their investigation. Different K/T boundary section have been analyzed so far for ^187Os/^186Os. An overview of the values is presented in the table. Boundary Clay layer Os ratio Reference Stevns Klint fish clay 1.66 Luck and Turekian, 1983 Woodside Creek 1.12 Lichte et al., 1986 Raton Basin 1.23 Kraehenbuehl et al., 1988 Raton Basin (several) 1.15-1.23 Esser and Turekian, 1989 Sumbar (0-1 cm) 1.16 This work We obtained a complete marine section of the K/T boundary in southern Turkmenia (decribed by Alekseyev, 1988). It shows a very high Ir concentration (66 ppb) at the boundary layer and a remarkable Ir enrichment over crustal rocks continuing up to 30 cm above the boundary. Our aim of this investigation is to analyze several samples from above and below the boundary for the ^187Os/^186Os ratio to obtain a complete picture of the isotopic evolution of the section. We want to evaluate mixing of Os with chondritic ratios with Os from upper crustal rocks. Another goal is to investigate a mobilization of Os. So far only one sample has been analyzed with NTI-MS after fire assay digestion of the sample. The sample 0 to 1 cm has an ^187Os/^186Os ratio of 1.162 +- 13, which is quite low. We expect an even lower value for the boundary clay (0 cm) itself not taking into account a contribution of radiogenic osmium from the decay of terrestrial rhenium. This might put this K/T boundary section closest of all to the present day chondritic value (approx. 1.05). Further analysis will be presented at the meeting. References Alekseyev A. S., Nazarov M. A

  19. Systematic Osmium Isotope Binary Mixing Arrays in Arc Volcanism

    Science.gov (United States)

    Alves, S.; Alves, S.; Schiano, P.; Capmas, F.; Allegre, C. J.

    2001-12-01

    Isotopic and geochemical studies on subduction-related lavas aim at constraining the nature of their mantle sources and the respective roles of source heterogeneity and petrogenetic processes in their compositions. Many components are potentially involved in producing the geochemical signatures of arc lavas: depleted mantle, subducted oceanic crust and sediments, and the overlying continental or oceanic crust. A further complication in characterizing mantle sources of arc lavas is complex mixing of some component parts via derivative fluids or melts released from the slab. Os isotope ratios are potential tracers of slab contribution in arc lavas because 1) subducted sediments are very radiogenic in Os compared to the upper mantle, and 2) Re behaves as a moderately incompatible element during mantle partial melting, whereas Os is highly compatible. Therefore, MORB have much higher Re/Os ratios than peridotites. Consequently, old oceanic crust is likely to be extremely more radiogenic than the depleted upper mantle so that recycled basaltic components should be identified by their elevated 187Os/188Os ratios. Os isotope ratios and Os and Re concentrations have been measured in 55 lavas coming from 10 different subduction zones. Samples span a large range of major element concentrations (from basalts to dacites) and Mg# (from 0.32 to 0.81). The 10 subduction zones, namely the Lesser Antilles, Java, Papua-New Guinea, the Philippines, Izu-Bonin, Kamchatka, the Aleutians, Mexico, Colombia and Peru-Chile, have a range of basement nature and thickness, as well as a range of age and sediment cover of the subducting plate. Measured 187Os/188Os ratios range from 0.130 to 1.524 and Os concentrations range from 0.048 to 46 ppt. Re concentrations range from 37 to 915 ppt. Os initial isotope ratios are systematically positively and linearly correlated with the inverse of Os concentrations in arc lavas from a given volcano, indicating that the Os isotopic compositions always

  20. Linguistic Dating of Biblical Texts

    DEFF Research Database (Denmark)

    Ehrensvärd, Martin Gustaf

    2003-01-01

    For two centuries, scholars have pointed to consistent differences in the Hebrew of certain biblical texts and interpreted these differences as reflecting the date of composition of the texts. Until the 1980s, this was quite uncontroversial as the linguistic findings largely confirmed...... the chronology of the texts established by other means: the Hebrew of Genesis-2 Kings was judged to be early and that of Esther, Daniel, Ezra, Nehemiah, and Chronicles to be late. In the current debate where revisionists have questioned the traditional dating, linguistic arguments in the dating of texts have...... come more into focus. The study critically examines some linguistic arguments adduced to support the traditional position, and reviewing the arguments it points to weaknesses in the linguistic dating of EBH texts to pre-exilic times. When viewing the linguistic evidence in isolation it will be clear...

  1. Date stones in broiler's feeding

    Directory of Open Access Journals (Sweden)

    Gualtieri, M.

    1990-01-01

    Full Text Available To evaluate date stones as dietary component for broilers, two trials were carried out. In the first trial, Tunisian Deglet date stones were used and in the second one, stones were the waste product of an Italian distillery. One-day-old Arbor Acres chickens were cage reared and fed for 6 weeks on 4 experimental diets, which were formulated to be isonitrogenous and isocaloric and differed in cereal component (maize or low tannin sorghum and in inclusion level (0 or 10 % of ground date stones. Birds ' performances were slightly different in the two trials, but overall results indicate that date stones are suitable for use in broiler's feeding under such conditions.

  2. 31 CFR 536.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 536.302 Section 536... Definitions § 536.302 Effective date. The term effective date refers to the effective date of the applicable... of specially designated narcotics traffickers designated after that date, the earlier of the date...

  3. 31 CFR 595.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 595.302 Section 595... § 595.302 Effective date. The term effective date refers to the effective date of the applicable... of specially designated terrorists designated after that date, the earlier of the date on which...

  4. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface...... deposited during the Early Ordovician — a time of known redox instability in ancient oceans – exhibit a significant positive Cr isotope excursion of +0.5‰. This excursion is interpreted as the reductive drawn down of dissolved Cr in seawater in response to the development of a proximal anoxic sink......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river water and to quantify...

  5. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    Greenland ice cores offer a unique opportunity to investigate the climate system behaviour. The objective of this PhD project is to investigate isotope modelling of present- day conditions and conduct model-data comparison using Greenland ice cores. Thus this thesis investigates how the integration...... of model and data can be used to improve the understanding of climate changes. This is done through analysis of isotope modelling, observations and ice core measurements. This dissertation comprises three projects: (1) Modelling the isotopic response to changes in Arctic sea surface conditions, (2......) Constructing a new Greenland database of observations and present-day ice core measurements, and (3) Performance test of isotope-enabled CAM5 for Greenland. The recent decades of rapid Arctic sea ice decline are used as a basis for an observational-based model experiment using the isotope-enabled CAM model 3...

  6. Microscale radiocarbon dating of paintings

    Science.gov (United States)

    Hendriks, Laura; Hajdas, Irka; McIntyre, Cameron; Küffner, Markus; Scherrer, Nadim C.; Ferreira, Ester S. B.

    2016-03-01

    In this paper, radiocarbon dating of paintings using minimal sample sizes has been investigated, in an effort to address the problem of limited access to sample material in paintings. 14C analyses were conducted on signed and dated paintings from two Swiss artists of the twentieth century. The selected paintings dated from the 1930s and 1960s, provided the opportunity to evaluate the dating accuracy on paintings realized before and after 1950 AD when the 14C bomb peak was created, as a result of the nuclear tests conducted in the 1950/1960s. The work focused on the one hand on minimizing the size of the canvas sample required for accelerator mass spectrometer radiocarbon measurement on the gas ion source of the MICADAS and, on the other hand, on testing the possibility of dating the organic binder of the paint. Following careful characterization of the paint composition by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy, paints containing no other carbon source than the natural organic binder were identified and dated.

  7. Microscale radiocarbon dating of paintings

    Energy Technology Data Exchange (ETDEWEB)

    Hendriks, Laura; Hajdas, Irka; McIntyre, Cameron [ETH Zurich, Ion Beam Physics, Zurich (Switzerland); Kueffner, Markus; Ferreira, Ester S.B. [SIK-ISEA, Zurich, Zurich (Switzerland); Scherrer, Nadim C. [Bern University of Applied Sciences, HKB, Bern (Switzerland)

    2016-03-15

    In this paper, radiocarbon dating of paintings using minimal sample sizes has been investigated, in an effort to address the problem of limited access to sample material in paintings. {sup 14}C analyses were conducted on signed and dated paintings from two Swiss artists of the twentieth century. The selected paintings dated from the 1930s and 1960s, provided the opportunity to evaluate the dating accuracy on paintings realized before and after 1950 AD when the {sup 14}C bomb peak was created, as a result of the nuclear tests conducted in the 1950/1960s. The work focused on the one hand on minimizing the size of the canvas sample required for accelerator mass spectrometer radiocarbon measurement on the gas ion source of the MICADAS and, on the other hand, on testing the possibility of dating the organic binder of the paint. Following careful characterization of the paint composition by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy, paints containing no other carbon source than the natural organic binder were identified and dated. (orig.)

  8. Titan's Isotopic Menagerie: The Cassini CIRS Perspective

    Science.gov (United States)

    Nixon, Conor A.; Achterberg, R. K.; Bezard, B.; Bjoraker, G. L.; Coustenis, A.; de Kok, R.; Flasar, F. M.; Hewagama, T.; Irwin, P. G. J.; Jennings, D. E.; Jolly, A.; Romani, P. N.; Teanby, N. A.; Vinatier, S.; CIRS Team

    2008-09-01

    Saturn's long-mysterious moon Titan is gradually yielding up its secrets under the intense scrutiny of the Cassini spacecraft, which has just completed a 4-year prime mission including 45 close flybys of the giant satellite. We here focus on the isotopic composition of the stratosphere, which since Voyager 1 in 1980 has been known to comprise a surprisingly rich mixture of hydrocarbons, nitriles and several oxygen species. These molecules are now understood to originate in the upper atmosphere by chemical processes initiated by the dissociation of the most abundant native species - methane and nitrogen - with some oxygen added from externally-supplied water. Measurements of isotopic ratios in these compounds are important and can provide valuable information on the formation and evolution of Titan's atmosphere. E.g. Chemical processes can cause isotopic fractionation via the 'kinetic isotope effect' (KIE). Cassini's Composite Infrared Spectrometer (CIRS), which is sensitive to thermal infrared radiation from 10-1500 cm-1 (7-1000 micron), is an ideal tool for measuring molecular concentrations and can distinguish between isotopologues due to the shifts in the molecular bands. CIRS has now identified at least eleven isotopologue species in our spectra, with multiple new detections in the past year (13CO2, CO18O, HC13CCCN). CIRS has measured the ratios 12C/13C in a total of seven species, D/H in two species, and 14N/15N and 16O/18O each in one species - the best measurement so far of the important ratio 16O/18O on Titan (346±110). In this presentation we will summarize all our results to date on isotopic ratios, including comparison with Huygens GCMS and other determinations, a discussion of possible isotopic separation in hydrocarbon chains, and formation/evolution implications of these measurements for Titan.

  9. Pyrolysis-combustion 14C dating of soil organic matter

    Science.gov (United States)

    Wang, Hong; Hackley, Keith C.; Panno, Samuel V.; Coleman, Dennis D.; Liu, Jack Chao-li; Brown, Johnie

    2003-11-01

    Radiocarbon ( 14C) dating of total soil organic matter (SOM) often yields results inconsistent with the stratigraphic sequence. The onerous chemical extractions for SOM fractions do not always produce satisfactory 14C dates. In an effort to develop an alternative method, the pyrolysis-combustion technique was investigated to partition SOM into pyrolysis volatile (Py-V) and pyrolysis residue (Py-R) fractions. The Py-V fractions obtained from a thick glacigenic loess succession in Illinois yielded 14C dates much younger but more reasonable than the counterpart Py-R fractions for the soil residence time. Carbon isotopic composition (δ 13C) was heavier in the Py-V fractions, suggesting a greater abundance of carbohydrate- and protein-related constituents, and δ 13C was lighter in the Py-R fractions, suggesting more lignin- and lipid-related constituents. The combination of 14C dates and δ 13C values indicates that the Py-V fractions are less biodegradation resistant and the Py-R fractions are more biodegradation resistant. The pyrolysis-combustion method provides a less cumbersome approach for 14C dating of SOM fractions. With further study, this method may become a useful tool for analyzing unlithified terrestrial sediments when macrofossils are absent.

  10. Radiocarbon dating of fluvial organic matter reveals land-use impacts in boreal peatlands

    DEFF Research Database (Denmark)

    Hulatt, Chris J.; Kaartokallio, Hermanni; Oinonen, Markku

    2014-01-01

    This study measured the effects of land use on organic matter released to surface waters in a boreal peat catchment using radiocarbon dating of particulate and dissolved organic carbon (POC and DOC), DOC concentration, stable carbon and nitrogen isotope composition, and optical measurements. Undi...

  11. Direct radiocarbon dating and genetic analyses on the purported Neanderthal mandible from the Monti Lessini (Italy)

    DEFF Research Database (Denmark)

    Talamo, Sahra; Hajdinjak, Mateja; Mannino, Marcello

    2016-01-01

    of Riparo Mezzena in Northern Italy. In order to improve our understanding of prehistoric occupation at Mezzena, we analysed the human mandible and several cranial fragments from the site using radiocarbon dating, ancient DNA, ZooMS and isotope analyses. We also performed a more detailed investigation...

  12. New Radiocarbon Dates on Upper Mid-West Proboscideans: Determining Date Robustness

    Science.gov (United States)

    Hodgins, G.; Widga, C.; Lengyel, S. N.; Saunders, J.; Walker, J. D.

    2013-12-01

    With the objective of refining the picture of Megafaunal extinction patterns in the upper Midwest in the terminal Pleistocene, we have assembled for radiocarbon dating specimens from more than 80 distinct Mammut and Mammuthus remains from potentially late sites. So far, we have measurements for 65 bones, tusks and teeth, nearly double the extant number of published dates . These new specimens were all from museums rather than excavation sites, and 60% were known to be coated with a consolidant. The predominant consolidant was Butvar B-76, however shellac, Elmer's Glue, Glyptol were also noted in the conservation records, or deduced from knowledge of a particular museum's practices. Given the objective of the project is to identify extinction patterns, coupled with the wide prevalence of consolidants amongst the specimen set, it was imperative that testing be carried out to confirm that radiocarbon laboratory protocols removed the consolidants, so that ultimately the dates can be considered robust. To this end, key specimens were dated three times using different sample preparation protocols. These were 1) a solvent extraction followed by a modified Longin-plus -Base continuous flow collagen extraction method used in the NSF-Arizona AMS facility, 2) the solvent/modified Longin method plus ultrafiltration, and 3) solvent/modified Longin method plus hydroxyproline single amino acid dating. Among the specimens subjected to triplicate testing were some of the youngest late Wisconsin proboscidean specimens from the Upper Midwest Region. The data reveal general agreement between the different protocols, and suggested either limited penetration of consolidants into the specimens, or that the standard laboratory cleaning protocols were sufficient to remove traces from deep within bone, tooth or tusk tissue. The preservation of each specimen, recorded in terms of collagen content, C/N ratio and stable isotope values, indicated that most were actually well preserved, implying

  13. 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.

  14. Kimberley rock art dating project

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, G.L. [Takarakka Rock Art Research Centre, NT, (Australia); Morwood, M. [New England University, Armidale, NSW, (Australia). Dept of Archaeology and Palaeoanthropology

    1997-12-31

    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.

  15. The complexity behind the date

    CERN Document Server

    2009-01-01

    For the waiting world, and indeed for most of us here at CERN, ‘the LHC schedule’ simply means the date that the LHC will restart - and we only take notice when that end-date changes. But in fact the schedule is a constantly evolving intricate document coordinating all the repairs, consolidation and commissioning in every part of the machine. So, what actually goes on behind the scenes in timing and planning all the work on one of the most complex scientific instruments ever built?

  16. Methodological aspects about the use of the radicarbon dating in historical time sites

    Directory of Open Access Journals (Sweden)

    Lubritto, Carmine

    2009-01-01

    Full Text Available In this paper basic concepts concerning radiocarbon dating and Accelerator Mass Spectrometry (AMS technique, and specifically the Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE Laboratory AMS facility, will be given. Problem of contaminations in radiocarbon AMS measurements will be introduced, and the sample preparation laboratory and the graphitisation lines that are used at the CIRCE Laboratory will be presented. Moreover problems of sampling and interpretation of the archaeological radiocarbon dates will be treated in consideration of the nature of interdisciplinary research and of the impact of radiocarbon dating on archaeology.

  17. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    the Arctic Ocean. A comprehensive database is created based on ice core and weather station data from Greenland within the period 1890-2014. Present day annual and seasonal mean values are computed for 326 locations in Greenland. Parameterization of the spatial distribution of temperature and δ18O are used...... of model and data can be used to improve the understanding of climate changes. This is done through analysis of isotope modelling, observations and ice core measurements. This dissertation comprises three projects: (1) Modelling the isotopic response to changes in Arctic sea surface conditions, (2......) Constructing a new Greenland database of observations and present-day ice core measurements, and (3) Performance test of isotope-enabled CAM5 for Greenland. The recent decades of rapid Arctic sea ice decline are used as a basis for an observational-based model experiment using the isotope-enabled CAM model 3...

  18. Perchlorate isotope forensics

    Science.gov (United States)

    Böhlke, J.K.; Sturchio, N.C.; Gu, B.; Horita, J.; Brown, G.M.; Jackson, W.A.; Batista, J.; Hatzinger, P.B.

    2005-01-01

    Perchlorate has been detected recently in a variety of soils, waters, plants, and food products at levels that may be detrimental to human health. These discoveries have generated considerable interest in perchlorate source identification. In this study, comprehensive stable isotope analyses ( 37Cl/35Cl and 18O/17O/ 16O) of perchlorate from known synthetic and natural sources reveal systematic differences in isotopic characteristics that are related to the formation mechanisms. In addition, isotopic analyses of perchlorate extracted from groundwater and surface water demonstrate the feasibility of identifying perchlorate sources in contaminated environments on the basis of this technique. Both natural and synthetic sources of perchlorate have been identified in water samples from some perchlorate occurrences in the United States by the isotopic method. ?? 2005 American Chemical Society.

  19. Isotope Production Facility (IPF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Los Alamos National Laboratory has produced radioactive isotopes for medicine and research since the mid 1970s, when targets were first irradiated using the 800...

  20. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  1. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, E.E.

    2004-11-15

    A review of recent research involving isotopically controlled semiconductors is presented. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, can be considered the most important one for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples. Manuel Cardona, the longtime editor-in-chief of Solid State Communications has been and continues to be one of the major contributors to this field of solid state physics and it is a great pleasure to dedicate this review to him.

  2. Isotopes through the looking glass

    Science.gov (United States)

    Mårtensson Pendrill, Ann Marie

    2000-08-01

    Nuclear distributions affect many aspects of atomic spectra. As an example, recent experimental results for the hyperfine anomaly in Fr isotopes are considered. These depend on nuclear charge and magnetization distributions. The variations in charge radii for these isotopes were studied earlier by measuring optical isotope shifts. The hyperfine anomalies for the odd-odd isotopes involve the neutron distributions, of interest for studies of parity nonconserving effects along a chain of isotopes.

  3. 31 CFR 593.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 593.302 Section 593... REGULATIONS General Definitions § 593.302 Effective date. The term effective date refers to the effective date...)(2), the earlier of the date of actual or constructive notice of such person's designation....

  4. 31 CFR 548.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 548.302 Section 548....302 Effective date. The term effective date refers to the effective date of the applicable... pursuant to § 548.201(a), the earlier of the date of actual or constructive notice that such...

  5. 21 CFR 1312.25 - Expiration date.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Expiration date. 1312.25 Section 1312.25 Food and... SUBSTANCES Exportation of Controlled Substances § 1312.25 Expiration date. An export permit shall not be valid after the date specified therein, which date shall conform to the expiration date specified in...

  6. 31 CFR 541.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 541.302 Section 541... § 541.302 Effective date. The term effective date refers to the effective date of the applicable....201(a)(2), the earlier of the date on which either actual notice or constructive notice is received...

  7. 31 CFR 544.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 544.302 Section 544... REGULATIONS General Definitions § 544.302 Effective date. The term effective date refers to the effective date... property are blocked pursuant to § 544.201(a)(2), (a)(3), or (a)(4), the earlier of the date of actual...

  8. 31 CFR 547.303 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 547.303 Section 547... General Definitions § 547.303 Effective date. The term effective date refers to the effective date of the... blocked pursuant to § 547.201(a)(2), the earlier of the date of actual or constructive notice of...

  9. 31 CFR 551.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 551.302 Section 551....302 Effective date. The term effective date refers to the effective date of the applicable... the date of actual or constructive notice that such person's property and interests in property...

  10. 31 CFR 546.303 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 546.303 Section 546....303 Effective date. The term effective date refers to the effective date of the applicable... § 546.201(a)(2), the earlier of the date of actual or constructive notice of such person's designation....

  11. 31 CFR 543.303 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 543.303 Section 543... Definitions § 543.303 Effective date. The term effective date refers to the effective date of the applicable... § 543.201(a)(2), the earlier of the date of actual or constructive notice of such person's designation....

  12. 31 CFR 537.303 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 537.303 Section 537....303 Effective date. The term effective date refers to the effective date of the applicable... property of persons designated pursuant to § 537.201(a)(2), the earlier of the date on which either...

  13. 31 CFR 594.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 594.302 Section 594... Definitions § 594.302 Effective date. The term effective date refers to the effective date of the applicable... to § 594.201(a)(2), (a)(3), or (a)(4), the earlier of the date on which is received actual...

  14. 31 CFR 588.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 588.302 Section 588... Definitions § 588.302 Effective date. The term effective date refers to the effective date of the applicable... § 588.201(a)(2), the earlier of the date on which is received actual or constructive notice of...

  15. In situ SIMS U-Pb dating of hydrothermal rutile: reliable age for the Zhesang Carlin-type gold deposit in the golden triangle region, SW China

    Science.gov (United States)

    Pi, Qiaohui; Hu, Ruizhong; Xiong, Bin; Li, Qiuli; Zhong, Richen

    2017-02-01

    The contiguous region between Guangxi, Guizhou, and Yunnan, commonly referred to as the Golden Triangle region in SW China, hosts many Carlin-type gold deposits. Previously, the ages of the gold mineralization in this region have not been well constrained due to the lack of suitable minerals for radiometric dating. This paper reports the first SIMS U-Pb age of hydrothermal rutile crystals for the Zhesang Carlin-type gold deposit in the region. The hydrothermal U-bearing rutile associated with gold-bearing sulfides in the deposit yields an U-Pb age of 213.6 ± 5.4 Ma, which is within the range of the previously reported arsenopyrite Re-Os isochron ages (204 ± 19 to 235 ± 33 Ma) for three other Carlin-type gold deposits in the region. Our new and more precise rutile U-Pb age confirms that the gold mineralization was contemporaneous with the Triassic W-Sn mineralization and associated granitic magmatism in the surrounding regions. Based on the temporal correlation, we postulate that coeval granitic plutons may be present at greater depths in the Golden Triangle region and that the formation of the Carlin-type gold deposits is probably linked to the coeval granitic magmatism in the region. This study clearly demonstrates that in situ rutile U-Pb dating is a robust tool for the geochronogical study of hydrothermal deposits that contain hydrothermal rutile.

  16. Oxygen Isotopes in Meteorites

    Science.gov (United States)

    Clayton, R. N.

    2003-12-01

    Oxygen isotope abundance variations in meteorites are very useful in elucidating chemical and physical processes that occurred during the formation of the solar system (Clayton, 1993). On Earth, the mean abundances of the three stable isotopes are 16O: 99.76%, 17O: 0.039%, and 18O: 0.202%. It is conventional to express variations in abundances of the isotopes in terms of isotopic ratios, relative to an arbitrary standard, called SMOW (for standard mean ocean water), as follows:The isotopic composition of any sample can then be represented by one point on a "three-isotope plot," a graph of δ17O versus δ18O. It will be seen that such plots are invaluable in interpreting meteoritic data. Figure 1 shows schematically the effect of various processes on an initial composition at the center of the diagram. Almost all terrestrial materials lie along a "fractionation" trend; most meteoritic materials lie near a line of "16O addition" (or subtraction). (4K)Figure 1. Schematic representation of various isotopic processes shown on an oxygen three-isotope plot. Almost all terrestrial materials plot along a line of "fractionation"; most primitive meteoritic materials plot near a line of "16O addition." The three isotopes of oxygen are produced by nucleosynthesis in stars, but by different nuclear processes in different stellar environments. The principal isotope, 16O, is a primary isotope (capable of being produced from hydrogen and helium alone), formed in massive stars (>10 solar masses), and ejected by supernova explosions. The two rare isotopes are secondary nuclei (produced in stars from nuclei formed in an earlier generation of stars), with 17O coming primarily from low- and intermediate-mass stars (shielding in the UV photodissociation of CO (van Dishoeck and Black, 1988). This process results from the large differences in abundance between C16O, on the one hand, and C17O and C18O on the other. Photolysis of CO occurs by absorption of stellar UV radiation in the

  17. Online Dating and Conjugal Bereavement

    Science.gov (United States)

    Young, Dannagal Goldthwaite; Caplan, Scott E.

    2010-01-01

    This study examined self-presentation in the online dating profiles of 241 widowed and 280 divorced individuals between 18 and 40 years old. A content analysis of open-ended user-generated profiles assessed the presence or absence of various themes, including the user's marital status, the backstory of their lost relationship, and whether they…

  18. Heterodynes dominate precipitation isotopes in the East Asian monsoon region, reflecting interaction of multiple climate factors

    Science.gov (United States)

    Thomas, Elizabeth K.; Clemens, Steven C.; Sun, Youbin; Prell, Warren L.; Huang, Yongsong; Gao, Li; Loomis, Shannon; Chen, Guangshan; Liu, Zhengyu

    2016-12-01

    For the past decade, East Asian monsoon history has been interpreted in the context of an exceptionally well-dated, high-resolution composite record of speleothem oxygen isotopes (δ18Ocave) from the Yangtze River Valley. This record is characterized by a unique spectral response, with variance concentrated predominantly within the precession band and an enigmatic lack of variance at the eccentricity and obliquity bands. Here we examine the spectral characteristics of all existing >250-kyr-long terrestrial water isotope records in Asia, including a new water isotope record using leaf wax hydrogen isotope ratios from the Chinese Loess Plateau. There exist profound differences in spectral characteristics among all orbital-scale Asian water isotope records. We demonstrate that these differences result from latitudinal gradients in the influence of the winter and summer monsoons, both of which impact climate and water isotopes throughout East Asia. Water isotope records therefore do not reflect precipitation during a single season or from a single circulation system. Rather, water isotope records in East Asia reflect the complex interplay of oceanic and continental moisture sources, operating at multiple Earth-orbital periods. These non-linear interactions are reflected in water isotope spectra by the presence of heterodynes. Although complex, we submit that water isotope records, when paired with rapidly developing isotope-enabled model simulations, will have the potential to elucidate mechanisms causing seasonal precipitation variability and moisture source variability in East Asia.

  19. Radiocarbon dating in archaeology: Interdisciplinary aspects and consequences (an overview)

    Science.gov (United States)

    Palincaş, Nona

    2017-06-01

    This paper is an overview of recent developments in the radiocarbon dating of the most frequently analyzed archaeological materials - wood, short-lived plants, and human and animal bones - and draws attention to two sets of consequences. Firstly, while radiocarbon dating has become more accessible to archaeologists thanks to an increase in the number of laboratories, a lowering of prices, and a reduction in sample sizes, it has also grown far more dependent on fields of research, other than the traditional chemical pretreatment of samples and the physics involved in their measurement, such as wood anatomy and other fields of botany, stable isotope-based diet studies, geochemistry, micromorphology, statistics, etc., most of which are not easily accessible by the vast majority of users of radiocarbon dating (and sometimes not familiar to practicing archaeologists). Secondly, given that, on the one hand, there is still much scope for research in radiocarbon dating and, on the other, archaeological sites are a limited resource, there is need to create archives containing the detailed documentation of samples and, whenever possible, sample residues.

  20. 40Ar/39Ar dating of Daqingshan thrust

    Institute of Scientific and Technical Information of China (English)

    LIU Zhenghong; XU Zhongyuan; YANG Zhensheng

    2003-01-01

    The Daqingshan thrust system, to the south of the Shiguai Mesozoic basin, is a complex system of top-to- the-north thrusting tectonic sheets. The thrust system has a complicated evolution due to multi-stage thrusting. In order to date the thrusting events, syntectonic muscovite and biotite grains are respectively analyzed with normal 40Ar/39Ar dating and laser 40Ar/39Ar dating, which yield 2 isochron ages, i.e. 193.74 ± 3.88 Ma and 121.6 ± 1.6 Ma. These ages suggest that faults within the Daqingshan thrust system formed during 2 stages of thrusting, one the early Indosinian and the other the late Yanshanian. The isotopic dating is consistent with field geological relations. Indosinan deformation is evidenced by top-to-the-north thrusting, with the occurrence of a series of large-scale east-west trending thrust faults and folds, while the Yanshanian thrusting is characterized by top-to-the-NNW thrusting. It is superposed on and modifies early Indosinian thrust faults.

  1. What to Expect After Your Due Date

    Science.gov (United States)

    ... Management Education & Events Advocacy For Patients About ACOG What to Expect After Your Due Date Home For ... Your Due Date FAQ069, August 2011 PDF Format What to Expect After Your Due Date Pregnancy What ...

  2. U-Pb Dating of Calcite by LA-ICPMS

    Science.gov (United States)

    Hacker, B. R.; Kylander-Clark, A. R.; Holder, R. M.; Nuriel, P.

    2016-12-01

    An emerging frontier area in geochronology is U-Pb dating of carbonate minerals by laser-ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The spate of papers over the last few years applying LA-ICPMS to carbonate dating stems from the capability of LA-ICPMS to deal with the variable, and often low, U/Pb ratios of carbonate. LA-ICPMS is an excellent tool for efficiently screening out samples with low U/Pb ratios and provides the ability to measure many spots with different U/Pb ratios and obtain dates free of assumptions about the composition of common Pb. Because this technique is in its infancy, important questions remain. What percentage of carbonate samples have high enough U/Pbc ratios that they can be dated? What percentage of samples yield isochronous datasets? What are the limits on precision and accuracy of carbonate U/Pb dates? What is the best analytical method in the absence of isotopically homogeneous reference materials? Through the generosity of our colleagues we have acquired 8 reference materials ranging in age from 3 to 250 Ma. We have analyzed 125 unknowns from a variety of locations using a 193 nm ns laser with an 80-100 μm spot and a Nu Plasma HR-ES. We measure 207Pb/206Pb using NIST 614 glass and then calculate a 206Pb/238U correction factor based on the measured vs. known ages of the reference materials. Sixty of these samples ( 50%) have high enough U/Pb ratios that they can be dated. There is great heterogeneity among the sample suites: some have no datable samples, whereas one suite of 68 samples yielded 53 datable rocks. Of the samples with high U/Pbc ratios, a majority yielded isochronous U-Pb data, indicating that the U-Pb system closed at a given time and was not subsequently disturbed.

  3. Linguistic dating of biblical texts

    DEFF Research Database (Denmark)

    Young, Ian; Rezetko, Robert; Ehrensvärd, Martin Gustaf

    Since the beginning of critical scholarship biblical texts have been dated using linguistic evidence. In recent years this has become a controversial topic, especially with the publication of Ian Young (ed.), Biblical Hebrew: Studies in Chronology and Typology (2003). However, until now there has...... in the history of biblical Hebrew, but instead represent co-existing styles of literary Hebrew throughout the biblical period....... and diglossia and textual criticism (Chapters 7, 13), and the significance of extra-biblical sources, including Amarna Canaanite, Ugaritic, Aramaic, Hebrew inscriptions of the monarchic period, Qumran and Mishnaic Hebrew, the Hebrew language of Ben Sira and Bar Kochba, and also Egyptian, Akkadian, Persian....... This is followed by an detailed synthesis of the topics introduced in the first volume, a series of detailed case studies on various linguistic issues, extensive tables of grammatical and lexical features, and a comprehensive bibliography. The authors argue that the scholarly use of language in dating biblical...

  4. In situ isotopic analyses of U and Pb in zircon by remotely operated SHRIMP II, and Hf by LA-ICP-MS: an example of dating and genetic evolution of zircon by {sup 176}Hf/{sup 177}Hf from the Ita Quarry in the Atuba Complex, SE, Brazil; Analises in situ de U e Pb em zircao por SRIMP II por controle remoto e de Hf por LA-ICP-MS: um exemplo de datacao e da evolucao genetica de zircao atraves da razao {sup 176}Hf/{sup 177} em amostra da Pedreira Ita no Complexo Atuba, SE, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Siga Junior, Oswaldo; McReath, Ian; Sproesser, Walter; Basei, Miguel Angelo Stipp [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Centro de Pesquisas Geocronologicas], e-mail: keisato@usp.br, e-mail: osigajr@usp.br, e-mail: ianmcr@usp.br, e-mail: wmspres@usp.br, e-mail: baseimas@usp.br; Silva, Josiane Aline da [Universidade de Sao Paulo (USP), SP (Brazil). Programa de Pos-graduacao em Geoquimica e Geotectonica; Dunyi, Liu [Institute of Geology, Beijing (China); Iizuka, Takafumi; Rino, Shuji; Hirata, Takafumi [Tokyo Institute of Technology, Tokyo (Japan)

    2009-10-15

    Remotely-operated SHRIMP dating of zircon is an interesting alternative for dating of zircon crystals. Although it does not represent any technical progress of the geochronological method using the U-Pb system in zircon it is a very useful and cheap facility. The procedure was first used for mass spectrometric analyses involving two international laboratories in Sao Paulo, Brazil and Beijing, China. It was applied to samples of three gneiss-migmatitic rocks from the Ita quarry in the Atuba Complex (located between the Luis Alves and the Apiai Domain) to test previous controversial hypotheses about its evolution. The presence of important archaean and paleo proterozoic components in the complex is confirmed by analyses of zircon found in probably neo proterozoic leucosomes. Diorite intrusion also occurred during the neo proterozoic, associated with the 0.6Ga continental collisions involved in the assembly of Gondwana. The determination of Hf isotope ratios by LA-ICP/MS represents a new option for checking the relative importance of mantle ({epsilon}{sub Hf} > 0) and crustal contributions (({epsilon}{sub Hf} < 0) during the growth of the zircon crystals. While the archaean component in the complex was derived from the mantle ({epsilon}{sub Hf} + 1.5 to + 8.7) the paleo proterozoic component had a crustal contribution ({epsilon}{sub Hf} - 9.1 to -10.1). (author)

  5. Current topics in ESR dating

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Anne R., E-mail: Anne.R.Skinner@williams.edu [Williams College, Williamstown, MA (United States)

    2011-09-15

    After over 25 years, the use of electron spin resonance (ESR) is well-established in dating sites of geological, paleontological and archaeological interest. Like any scientific technique, there have been changes in understanding and in methodology. Improvements have not, however, changed the observation that external dose calculations are still a significant source of uncertainty in ages. Examples from Europe, Africa and the Americans illustrate this point. For Pradayrol Cave (France), the occupation age, 330 ka, is unchallenged, making this the oldest known Neanderthal site in France. For Roc de Marsal, also in France, on the other hand, discrepancies between TL and sedimentary dose rates imply substantial differences in interpretation. In the Western Egyptian Desert, where artifacts and datable material are not well-correlated, the dating results show consistency with expectations based on global climate change, even in deflated sites. Climate change is also the question in geological studies in the Bahamas where, despite concerns about cosmic dose history, ESR dates confirm other evidence for sea level changes. We show that an uncertain age is not the same as an impossible one.

  6. 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.

  7. 西藏冈底斯厅宫铜矿侵入岩成因:LA-ICP-MS 锆石U-Pb 年龄、地球化学及 Sr-Nd-Pb 同位素证据%Petrogenesis of Intrusions in Tinggong Copper Deposit,Gangdese, Xizang(Tibet):Evidence from LA-ICP-MS Zircon U-Pb Dating, Petrogeochemical,and Sr-Nd-Pb Isotopic Composition

    Institute of Scientific and Technical Information of China (English)

    黄勇; 丁俊; 李光明; 董随亮; 黄瀚霄; 崔晓亮; 戴婕; 闫国强

    2015-01-01

    studies of above major granites are benefited for future exploration.LA-ICP-MS zircon U-Pb dating,major and trace elements,Rb-Sr,Sm-Nd,Pb isotope composition were test by this study.The results show that the age of above granites are 50.32 Ma,48.34 Ma,and 49.41 Ma,respectively,which are apparently older than that of mineralization.Above stocks belong to high-K calc-alkaline,weakly peraluminous,I-type granites.The REE patterns indicate a LREE rich,with weak /no HREE fractionation V-type model and strong depleted δEu,which are reverse with SiO2 content.All granites are rich in Th,U,K,Cs,and Rb,depleted in Ba,Nb,Sr,Ti.Whole rock Pb isotopic compositions show that calculated n(206 Pb)/n(204 Pb)n(207 Pb)/n(204 Pb),n(208 Pb)/n(204 Pb) are 18.414 ~18.5137,15.616 ~15.7039,38.6394 ~39.0029,respectively,indicating a high radio-Pb isotope composition.Calculated n(87 Sr)/n(86 Sr)and n(143 Nd)/n(144 Nd)restrict in narrow range:0.70320 ~0.70477, 0.51260 ~0.51265,respectively,with calculated positive εNd (t)(0.51 ~1.44).The above results indicate that spread magna are not related to the mineralization and derived from new lower crust/depleted mantle during the roll-back and break-off of northward subducted ocean crust,undergoing AFC process during emplace.

  8. Argon isotope fractionation induced by stepwise heating

    Science.gov (United States)

    Trieloff, Mario; Falter, Martina; Buikin, Alexei I.; Korochantseva, Ekaterina V.; Jessberger, Elmar K.; Altherr, Rainer

    2005-03-01

    Noble gas isotopes are widely used to elucidate the history of the rocks in which they have been trapped, either from distinct reservoirs or by accumulation following radioactive decay. To extract noble gases from their host rocks, stepwise heating is the most commonly used technique to deconvolve isotopically different components, e.g., atmospheric, in situ radiogenic, or excess radiogenic from mantle or crustal reservoirs. The accurate determination of the isotopic composition of these different components is of crucial importance, e.g., for ages obtained by 40Ar- 39Ar stepheating plateaus. However, diffusion theory-based model calculations predict that the stepwise thermal extraction process from mineral phases induces isotope fractionation and, hence, adulterates the original composition. Such effects are largely unconsidered, as they are small and a compelling experimental observation is lacking. We report the first unequivocal evidence for significant mass fractionation of argon isotopes during thermal extraction, observed on shungite, a carbon-rich Precambrian sedimentary rock. The degree of fractionation, as monitored by 38Ar/ 36Ar and 40Ar/ 36Ar ratios, very well agrees with theoretical predictions assuming an inverse square root dependence of diffusion coefficient and atomic mass, resulting in easier extraction of lighter isotopes. Hence, subatmospheric 40Ar/ 36Ar ratios obtained for argon extracted at low temperatures may not represent paleoatmospheric argon. Shungite argon resembles modern atmospheric composition, but constraints on the timing of trapping appear difficult to obtain, as shungites are multicomponent systems. In 40Ar- 39Ar stepwise heating, the isotope fractionation effect could cause systematic underestimations of plateau ages, between 0.15 and 0.4% depending on age, or considerably higher if samples contain appreciable atmospheric Ar. The magnitude of this effect is similar to the presently achieved uncertainties of this increasingly

  9. Isotope geochemistry. Biological signatures in clumped isotopes of O₂.

    Science.gov (United States)

    Yeung, Laurence Y; Ash, Jeanine L; Young, Edward D

    2015-04-24

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in (18)O(18)O and (17)O(18)O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling.

  10. 9 CFR 381.126 - Date of packing and date of processing; contents of cans.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Date of packing and date of processing... Containers § 381.126 Date of packing and date of processing; contents of cans. (a) Either the immediate... code or otherwise with the date of packing. If calendar dating is used, it must be accompanied by...

  11. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110429 Chang Yuan(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China);Xu Changhai(U-Th)/He Dating Method:α-Ejection Influence and Correction(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,25(4),2010,p.418-427,6 illus.,2 tables,53 refs.)Key words:He-He dating,Th-U datingAccording to the development of this technique,the factors which influence the helium dating results a

  12. Stable isotopes. Applications and production; Les isotopes stables. Applications - production

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, S.; Louvet, P.; Soulie, E. [eds.

    1994-12-31

    This conference presents 46 communications concerning stable isotope production, utilization and application, grouped in 6 sessions and posters. The various themes are: biological applications (pharmacology, medical diagnosis, metabolism and protein studies, toxicity and response studies, labelled compounds), analysis procedures (NMR analysis for macromolecules, tracer studies), nuclear applications (utilization of stable isotopes in nuclear reactors), biological, physical and chemical applications (mass transfer, mobility, crystallography, isotopic exchange), stable isotope production (ion chromatography, ion cyclotron resonance, cryogenic distillation).

  13. Deformation of C isotopes

    CERN Document Server

    Kanada-Enyo, Y

    2004-01-01

    Systematic analysis of the deformations of proton and neutron densities in even-even C isotopes was done based on the method of antisymmetrized molecular dynamics. The $E2$ transition strength was discussed in relation to the deformation. We analyze the $B(E2;2^+_1\\to 0^+_1)$ in $^{16}$C, which has been recently measured to be abnormally small. The results suggest the difference of the deformations between proton and neutron densities in the neutron-rich C isotopes. It was found that stable proton structure in C isotopes plays an important role in the enhancement the neutron skin structure as well as in the systematics of $B(E2)$ in the neutron-rich C.

  14. 31 CFR 575.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 575.302 Section 575.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF....302 Effective date. The term effective date refers to the effective date of the applicable...

  15. 31 CFR 538.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 538.302 Section 538.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... § 538.302 Effective date. The term effective date refers to the effective date of the...

  16. 31 CFR 592.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 592.302 Section 592.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... § 592.302 Effective date. The term effective date refers to the effective date of the...

  17. 31 CFR 587.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 587.302 Section 587...) MILOSEVIC SANCTIONS REGULATIONS General Definitions § 587.302 Effective date. The term effective date refers to the effective date of the applicable prohibitions and directives contained in this part, which...

  18. 10 CFR 2.807 - Effective date.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Effective date. 2.807 Section 2.807 Energy NUCLEAR... § 2.807 Effective date. The notice of adoption of a regulation will specify the effective date... relieving from restrictions, will be made not less than thirty (30) days prior to the effective date...

  19. 18 CFR 11.7 - Effective date.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Effective date. 11.7... Dams § 11.7 Effective date. All annual charges imposed under this subpart will be computed beginning on the effective date of the license unless some other date is fixed in the license....

  20. 31 CFR 542.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 542.302 Section 542....302 Effective date. With respect to a person whose property or interests in property are blocked pursuant to a designation under § 542.201(a), the effective date is the earlier of the date on which...

  1. 7 CFR 987.5 - Dates.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Dates. 987.5 Section 987.5 Agriculture Regulations of... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE DOMESTIC DATES PRODUCED OR PACKED IN RIVERSIDE COUNTY, CALIFORNIA Order Regulating Handling Definitions § 987.5 Dates. Dates means the...

  2. 31 CFR 597.305 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 597.305 Section 597... General Definitions § 597.305 Effective date. Except as that term is used in § 597.201(d), the term effective date refers to the effective date of the applicable prohibitions and directives contained in...

  3. 19 CFR 351.701 - Applicability dates.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Applicability dates. 351.701 Section 351.701... DUTIES Applicability Dates § 351.701 Applicability dates. The regulations contained in this part 351... governed by the regulations in effect on the date the petitions were filed or requests were made for...

  4. 11 CFR 7.28 - Hearing date.

    Science.gov (United States)

    2010-01-01

    ... 11 Federal Elections 1 2010-01-01 2010-01-01 false Hearing date. 7.28 Section 7.28 Federal... for Administrative Enforcement Proceedings § 7.28 Hearing date. (a) Setting of date by examiner. The examiner shall set the hearing at a reasonable time, date, and place. (b) Considerations....

  5. 40 CFR 141.60 - Effective dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Effective dates. 141.60 Section 141.60... and Maximum Residual Disinfectant Levels § 141.60 Effective dates. (a) The effective dates for § 141.61 are as follows: (1) The effective date for paragraphs (a)(1) through (a)(8) of § 141.61 is...

  6. 31 CFR 560.301 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 560.301 Section 560... § 560.301 Effective date. The effective date of the prohibitions and directives contained in subpart B of this part is 12:01 a.m., Eastern Daylight Time, August 20, 1997. For the effective date of...

  7. 31 CFR 596.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 596.302 Section 596.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... General Definitions § 596.302 Effective date. The term effective date refers to the effective date of...

  8. 40 CFR 469.21 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Compliance dates. 469.21 Section 469....21 Compliance dates. The compliance date for the BAT fluoride limitation is as soon as possible as determined by the permit writer but in no event later than November 8, 1985. The compliance date for PSES...

  9. 31 CFR 545.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 545.302 Section 545.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... Definitions § 545.302 Effective date. The term effective date refers to the effective date of the...

  10. 31 CFR 586.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 586.302 Section 586...) KOSOVO SANCTIONS REGULATIONS General Definitions § 586.302 Effective date. The term effective date refers to the effective date of the applicable prohibitions and directives contained in this part which...

  11. 31 CFR 585.301 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 585.301 Section 585.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... General Definitions § 585.301 Effective date. The term effective date refers to the effective date of...

  12. School Counselors' Role in Dating Violence Intervention

    Science.gov (United States)

    Craigen, Laurie M.; Sikes, April; Healey, Amanda; Hays, Danica

    2009-01-01

    Dating violence among adolescents is a major public health concern. The purpose of this paper is to examine five factors of which school counselors must be aware in order to recognize, intervene, and report incidence of dating violence. These factors are (a) understanding the diverse definitions of dating violence, (b) recognizing dating violence…

  13. Isotopes in Condensed Matter

    CERN Document Server

    G Plekhanov, Vladimir

    2013-01-01

    This book provides a concise introduction to the newly created sub-discipline of solid state physics isotopetronics. The role of isotopes in materials and their properties are describe  in this book. The problem of the enigma of the atomic mass in microphysics is briefly discussed.  The range of the applications of isotopes is wide: from biochemical process in living organisms to modern technical applications in quantum information. Isotopetronics promises to improve nanoelectronic and optoelectronic devices. With numerous illustrations this book is useful to researchers, engineers and graduate students.

  14. Atomic Weights and Isotopic Compositions

    Science.gov (United States)

    SRD 144 Atomic Weights and Isotopic Compositions (Web, free access)   The atomic weights are available for elements 1 through 111, and isotopic compositions or abundances are given when appropriate.

  15. Mass transfer and carbon isotope evolution in natural water systems

    Science.gov (United States)

    Wigley, T.M.L.; Plummer, L.N.; Pearson, F.J.

    1978-01-01

    This paper presents a theoretical treatment of the evolution of the carbon isotopes C13 and C14 in natural waters and in precipitates which derive from such waters. The effects of an arbitrary number of sources (such as dissolution of carbonate minerals and oxidation of organic material) and sinks (such as mineral precipitation, CO2 degassing and production of methane), and of equilibrium fractionation between solid, gas and aqueous phases are considered. The results are expressed as equations relating changes in isotopic composition to changes in conventional carbonate chemistry. One implication of the equations is that the isotopic composition of an aqueous phase may approach a limiting value whenever there are simultaneous inputs and outputs of carbonate. In order to unambiguously interpret isotopic data from carbonate precipitates and identify reactants and products in reacting natural waters, it is essential that isotopic changes are determined chiefly by reactant and product stoichiometry, independent of reaction path. We demonstrate that this is so by means of quantitative examples. The evolution equations are applied to: 1. (1) carbon-14 dating of groundwaters; 2. (2) interpretation of the isotopic composition of carbonate precipitates, carbonate cements and diagenetically altered carbonates; and 3. (3) the identification of chemical reaction stoichiometry. These applications are illustrated by examples which show the variation of ??C13 in solutions and in precipitates formed under a variety of conditions involving incongruent dissolution, CO2 degassing, methane production and mineral precipitation. ?? 1978.

  16. Uranium Isotope Ratios in Modern and Precambrian Soils

    Science.gov (United States)

    DeCorte, B.; Planavsky, N.; Wang, X.; Auerbach, D. J.; Knudsen, A. C.

    2015-12-01

    Uranium isotopes (δ238U values) are an emerging paleoredox proxy that can help to better understand the redox evolution of Earth's surface environment. Recently, uranium isotopes have been used to reconstruct ocean and atmospheric redox conditions (Montoya-Pino et al., 2010; Brennecka et al., 2011; Kendall et al., 2013; Dahl et al., 2014). However, to date, there have not been studies on paleosols, despite that paleosols are, arguably better suited to directly tracking the redox conditions of the atmosphere. Sedimentary δ238U variability requires the formation of the soluble, oxidized form of U, U(VI). The formation of U(VI) is generally thought to require oxygen levels orders of magnitude higher than prebiotic levels. Without significant U mobility, it would have been impossible to develop isotopically distinct pools of uranium in ancient Earth environments. Conversely, an active U redox cycle leads to significant variability in δ238U values. Here we present a temporally and geographically expansive uranium isotope record from paleosols and modern soils to better constrain atmospheric oxygen levels during the Precambrian. Preliminary U isotope measurements of paleosols are unfractionated (relative to igneous rocks), possibly because of limited fractionation during oxidation (e.g., {Wang, 2015 #478}) or insufficient atmospheric oxygen levels to oxidize U(IV)-bearing minerals in the bedrock. Further U isotope measurements of paleosols with comparison to modern soils will resolve this issue.

  17. Measuring Isotope Ratios Across the Solar System

    Science.gov (United States)

    Webster, Chris R.; Mahaffy, Paul R.

    2012-01-01

    Stable isotope ratios in C, H, N, O and S are powerful indicators of a wide variety of planetary geophysical processes that can identify origin, transport, temperature history, radiation exposure, atmospheric escape, environmental habitability and biology [1]. For the Allan Hills 84001 meteorite, for example, the (sup 1)(sup 3)C/(sup 1)(sup 2)C ratio identifies it as a Mars (SNC) meteorite; the ??K/??Ar ratio tells us the last time the rock cooled to solid, namely 4 Gya; isotope ratios in (sup 3)He, (sup 2)(sup 1)Ne and (sup 3)?Ar show it was in space (cosmic ray exposure) for 10-20 million years; (sup 1)?C dating that it sat in Antarctica for 13,000 years before discovery; and clumped isotope analysis of (sup 1)?O(sup 1)(sup 3)C(sup 1)?O in its carbonate that it was formed at 18+/-4 ?C in a near-surface aqueous environment [2]. Solar System Formation

  18. Measuring Isotope Ratios Across the Solar System

    Science.gov (United States)

    Webster, Chris R.; Mahaffy, Paul R.

    2012-01-01

    Stable isotope ratios in C, H, N, O and S are powerful indicators of a wide variety of planetary geophysical processes that can identify origin, transport, temperature history, radiation exposure, atmospheric escape, environmental habitability and biology [1]. For the Allan Hills 84001 meteorite, for example, the (sup 1)(sup 3)C/(sup 1)(sup 2)C ratio identifies it as a Mars (SNC) meteorite; the ??K/??Ar ratio tells us the last time the rock cooled to solid, namely 4 Gya; isotope ratios in (sup 3)He, (sup 2)(sup 1)Ne and (sup 3)?Ar show it was in space (cosmic ray exposure) for 10-20 million years; (sup 1)?C dating that it sat in Antarctica for 13,000 years before discovery; and clumped isotope analysis of (sup 1)?O(sup 1)(sup 3)C(sup 1)?O in its carbonate that it was formed at 18+/-4 ?C in a near-surface aqueous environment [2]. Solar System Formation

  19. Dilemma posed by uranium-series dates on archaeologically significant bones from Valsequillo, Puebla, Mexico

    Science.gov (United States)

    Szabo, B. J.; Malde, H.E.; Irwin-Williams, C.

    1969-01-01

    In an attempt to date stone artifacts of Early Man excavated from several sites at the Valsequillo Reservoir, a few kilometers south of Puebla, Mexico, Szabo applied the uranium-series method on bone samples known to be either from the same geologic formation as the sites or in direct association with the artifacts. The geologic context of the bones was studied by Malde, and the archaeological sites were excavated by Irwin-Williams. A date determined for bone associated with an artifact (Caulapan sample M-B-6, see below) agrees with a radiocarbon date for fossil mollusks in the same bed and indicates man's presence more than 20 000 years ago. However, some of these bone dates exceed 200 000 years. Because such dates for man in North America conflict with all prior archaeological evidence here and abroad, we are confronted by a dilemna - either to defend the dates against an onslaught of archaeological thought, or to abandon the uranium method in this application as being so much wasted effort. Faced with these equally undesirable alternatives, and unable to decide where the onus fairly lies (if a choice must be made), we give the uranium-series dates as a possible stimulus for further mutual work in isotopic dating of archaeological material. A sample from the Lindenmeier archaeological site north of Fort Collins and another from a Pleistocene terrace along the Arkansas River, both in Colorado, were also dated. ?? 1969.

  20. Abstracts of Papers Presented at the International Symposium on Time, Frequency and Dating in Geomorphology Held in Bratislava (Czechoslovakia) on 16- 21 June 1992

    Science.gov (United States)

    1992-06-21

    J., JULIAN, A.: Archaeological dating, geomorphological reconstructions and palaeoclimatic correlations in northern Spain...material, under Mediterranean climatic conditions, in Tarragona, Spain, were dated. The analyses also included micromorphology and stable isotopes. Age...correlation of archaeological findings with biostratigraphically treated sequences. Our data demonstrate a reasonable relationship between the relief changes

  1. Accounting the Events after the Balance Date

    OpenAIRE

    Ilincuţă Lucian-Dorel; Mareş Marius-Daniel; Mareş Valerica

    2014-01-01

    The events after the balance date are those events, favorable and unfavorable, that occur between the balance date (the end of the reporting period) and the date at which the annual financial statements are authorized for issue by the executive management of the entity (e.g. Board of Directors). We identify two types of events: events after the balance date, which lead to financial statements adjusting and events after the balance date, which do not lead to financ...

  2. Astronomical dating in the 19th century

    Science.gov (United States)

    Hilgen, Frederik J.

    2010-01-01

    Today astronomical tuning is widely accepted as numerical dating method after having revolutionised the age calibration of the geological archive and time scale over the last decades. However, its origin is not well known and tracing its roots is important especially from a science historic perspective. Astronomical tuning developed in consequence of the astronomical theory of the ice ages and was repeatedly used in the second half of the 19th century before the invention of radio-isotopic dating. Building upon earlier ideas of Joseph Adhémar, James Croll started to formulate his astronomical theory of the ice ages in 1864 according to which precession controlled ice ages occur alternatingly on both hemispheres at times of maximum eccentricity of the Earth's orbit. The publication of these ideas compelled Charles Lyell to revise his Principles of Geology and add Croll's theory, thus providing an alternative to his own geographical cause of the ice ages. Both Croll and Lyell initially tuned the last glacial epoch to the prominent eccentricity maximum 850,000 yr ago. This age was used as starting point by Lyell to calculate an age of 240 million years for the beginning of the Cambrium. But Croll soon revised the tuning to a much younger less prominent eccentricity maximum between 240,000 and 80,000 yr ago. In addition he tuned older glacial deposits of late Miocene and Eocene ages to eccentricity maxima around 800,000 and 2,800,000 yr ago. Archibald and James Geikie were the first to recognize interglacials during the last glacial epoch, as predicted by Croll's theory, and attempted to tune them to precession. Soon after Frank Taylor linked a series of 15 end-moraines left behind by the retreating ice sheet to precession to arrive at a possible age of 300,000 yr for the maximum glaciation. In a classic paper, Axel Blytt (1876) explained the scattered distribution of plant groups in Norway to precession induced alternating rainy and dry periods as recorded by the

  3. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    M Thoennessen

    2015-09-01

    Of the about 3000 isotopes presently known, about 20% have been discovered in fission. The history of fission as it relates to the discovery of isotopes as well as the various reaction mechanisms leading to isotope discoveries involving fission are presented.

  4. Tectonic calibrations in molecular dating

    Institute of Scientific and Technical Information of China (English)

    Ullasa KODANDARAMAIAH

    2011-01-01

    Molecular dating techniques require the use of calibrations, which are usually fossil or geological vicariance-based.Fossil calibrations have been criticised because they result only in minimum age estimates. Based on a historical biogeographic perspective, Ⅰ suggest that vicariance-based calibrations are more dangerous. Almost all analytical methods in historical biogeography are strongly biased towards inferring vicariance, hence vicariance identified through such methods is unreliable. Other studies, especially of groups found on Gondwanan fragments, have simply assumed vicariance. Although it was previously believed that vicariance was the predominant mode of speciation, mounting evidence now indicates that speciation by dispersal is common, dominating vicariance in several groups. Moreover, the possibility of speciation having occurred before the said geological event cannot be precluded. Thus, geological calibrations can under- or overestimate times, whereas fossil calibrations always result in minimum estimates. Another major drawback of vicariant calibrations is the problem of circular reasoning when the resulting estimates are used to infer ages of biogeographic events. Ⅰ argue that fossil-based dating is a superior alternative to vicariance, primarily because the strongest assumption in the latter, that speciation was caused by the said geological process, is more often than not the most tenuous. When authors prefer to use a combination of fossil and vicariant calibrations, one suggestion is to report results both with and without inclusion of the geological constraints. Relying solely on vicariant calibrations should be strictly avoided.

  5. GEOCHRONOMETRY ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正>20040631 Chen Jiangfeng (School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui) ; Xie Zhi Relationships Between Rb-Sr, Ar - Ar Geochronometers and Oxygen Isotopic Equilibrium of Intrusions from Eastern Anhui Province, China (Geological Journal of China Universities, ISSN 1006 - 7493, CN 32 -

  6. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20090432 Zhou Shuqing (School of Energy Resources, China University of Geosciences Beijing 100083, China); Huang Haiping Stable Isotopic Records vs. Important Events in Life Evolution and the Concurrent Environment (Geological Review, ISSN0371-5736, CN11-1952, 54(2), 2008, p.225-231, 3 illus., 1 table, 77 refs.)

  7. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20072750 Huang Sijing(State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China);Pei Changrong Age Calibration for the Boundary between Lower and Middle Triassic by Strontium Isotope Stratigraphy in Eastern Sichuan Province

  8. Isotopic Implicit Surface Meshing

    NARCIS (Netherlands)

    Boissonnat, Jean-Daniel; Cohen-Steiner, David; Vegter, Gert

    2004-01-01

    This paper addresses the problem of piecewise linear approximation of implicit surfaces. We first give a criterion ensuring that the zero-set of a smooth function and the one of a piecewise linear approximation of it are isotopic. Then, we deduce from this criterion an implicit surface meshing algor

  9. Isotope hydrograph separation

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, P. [UFZ-Umweltforschungszentrum, Centre of Environmental Research Leipzig-Halle, Leipzig (Germany)

    2000-07-01

    Storm-runoff thus reflects the complex hydraulic behaviour of drainage basins and water-links of such systems. Water of different origin may participate in the events and in this lecture, the application of isotope techniques to separate storm hydrographs into different components will be presented.

  10. Forensic Stable Isotope Biogeochemistry

    Science.gov (United States)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  11. 东准噶尔晚古生代次火山侵入岩锆石SHRIMP U-Pb年龄及Sr-Nd同位素地球化学%Zircon SHRIMP U-Pb Dating and Sr-Nd Isotopic Geochemistry of Late Paleozoic Subvolcanic-Intrusive Rocks in Eastern Junggar

    Institute of Scientific and Technical Information of China (English)

    张峰; 徐涛; 郭晓东; 范俊杰; 张栋; 潘爱军; 朝银银

    2014-01-01

    Late Paleozoicvolcanic-subvolcanic-intrusive rocks in Eastern Junggar are developed.Songkaersu granodiorite porphyry,as a part of them,formed in the southeast Kalamali tectonic belt.Petrography,SHRIMP zircon U-Pb and Sr-Nd isotope indicate that all zircons selected are magmatic, and the zircons U-Pb concordant ages of two samples may be sub-divided into many groups,of which the youngest concordant age is 305.5~316.3Ma which can be interpreted as the for-mation age of Songkaersu granodiorite porphyry.On the other hand,others ages such as early Cambrian to early Carbonif-erou are consistent with the ages of oceanic-crust and island-arc magmatic rocks around the Junggar Basin.Moreover,the positiveεNd(t)(3.0 to 15.1), medium 87Sr/86Sr initial ratios (0.703 861 to 0.713 151), and smaller T2DM (412 to 839) may imply that the eastern basement of the Junggar Basin was tectonically amalgamated by underplating of mantle-derived substances and different Paleozoic remnant oceanic crust and arc complexes upon the minor Precambrian continental crust . Songkaersu granodiorite porphyry may result from the interaction of a amount of new-born lower crust and minor asthenospheric mantle or depleted lithospheric mantle,and the formation mechanism of them perhaps might be related to the subduction of the Paleo-Asian oceanic plate under the Kazakhstan-Junggar plate and result in back-arc spreading.%东准噶尔地区石炭纪巴塔玛依内山组火山岩-次火山侵入岩发育。本文以卡拉麦里构造带东南部松喀尔苏地区次火山侵入岩--花岗闪长斑岩为研究对象,通过岩石学、SHRIMP锆石U-Pb和Sr-Nd同位素方面的研究发现,所有锆石都具岩浆成因,锆石U-Pb年龄可分为多组,其中最小的一组年龄为305.5~316.3 Ma,代表岩体的形成时间,其他年龄多与准噶尔地区产出的具洋壳和岛弧性质的岩浆岩时代一致。岩石具正的εNd(t)(3.0~15.1),中等的87Sr/86Sr初始值(0

  12. The isotope hydrology of Quaternary climate change.

    Science.gov (United States)

    Darling, W G

    2011-04-01

    Understanding the links between climate change and human migration and culture is an important theme in Quaternary archaeology. While oxygen and hydrogen stable isotopes in high-latitude ice cores provide the ultimate detailed record of palaeoclimate extending back to the Middle Pleistocene, groundwater can act as a climate archive for areas at lower latitudes, permitting a degree of calibration for proxy records such as lake sediments, bones, and organic matter. Not only can oxygen and hydrogen stable isotopes be measured on waters, but the temperature of recharge can be calculated from the amount of the atmospheric noble gases neon, argon, krypton, and xenon in solution, while residence time can be estimated from the decay of the radioisotopes carbon-14, chlorine-36, and krypton-81 over timescales comparable to the ice core record. The Pleistocene-Holocene transition is well characterised in aquifers worldwide, and it is apparent that isotope-temperature relationships of the present day are not necessarily transferable to past climatic regimes, with important implications for the interpretation of proxy isotope data. Groundwaters dating back to one million years, i.e., to beyond the Middle Pleistocene, are only found in major aquifer basins and information is relatively sparse and of low resolution. Speleothem fluid inclusions offer a way of considerably increasing this resolution, but both speleothem formation and large-scale groundwater recharge requires humid conditions, which may be relatively infrequent for areas currently experiencing arid climates. Both types of record therefore require caution in their interpretation when considering a particular archaeological context.

  13. Origin of uranium isotope variations in early solar nebula condensates.

    Science.gov (United States)

    Tissot, François L H; Dauphas, Nicolas; Grossman, Lawrence

    2016-03-01

    High-temperature condensates found in meteorites display uranium isotopic variations ((235)U/(238)U), which complicate dating the solar system's formation and whose origin remains mysterious. It is possible that these variations are due to the decay of the short-lived radionuclide (247)Cm (t 1/2 = 15.6 My) into (235)U, but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of (235)U reaching ~+6% relative to average solar system composition, which can only be due to the decay of (247)Cm. This allows us to constrain the (247)Cm/(235)U ratio at solar system formation to (1.1 ± 0.3) × 10(-4). This value provides new clues on the universality of the nucleosynthetic r-process of rapid neutron capture.

  14. Origin of uranium isotope variations in early solar nebula condensates

    CERN Document Server

    Tissot, Francois L H; Grossman, Lawrence

    2016-01-01

    High temperature condensates found in meteorites display uranium isotopic variations (235U/238U) that complicate dating of the formation of the Solar System and whose origin remains mysterious. It is possible that these variations are due to decay of the short-lived radionuclide 247Cm (t1/2=15.6 Myr) into 235U but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of 235U reaching ~+6 % relative to average solar system composition, which can only be due to decay of 247Cm. This allows us to constrain the 247Cm/235U ratio at Solar System formation to (1.1 +- 0.3) x 10-4. This value provides new clues on the universality of nucleosynthetic r-process of rapid neutron capture.

  15. Linguistic dating of biblical texts

    DEFF Research Database (Denmark)

    Young, Ian; Rezetko, Robert; Ehrensvärd, Martin Gustaf

    and diglossia and textual criticism (Chapters 7, 13), and the significance of extra-biblical sources, including Amarna Canaanite, Ugaritic, Aramaic, Hebrew inscriptions of the monarchic period, Qumran and Mishnaic Hebrew, the Hebrew language of Ben Sira and Bar Kochba, and also Egyptian, Akkadian, Persian....... This is followed by an detailed synthesis of the topics introduced in the first volume, a series of detailed case studies on various linguistic issues, extensive tables of grammatical and lexical features, and a comprehensive bibliography. The authors argue that the scholarly use of language in dating biblical...... texts, and even the traditional standpoint on the chronological development of biblical Hebrew, require a thorough re-evaluation, and propose a new perspective on linguistic variety in biblical Hebrew. Early Biblical Hebrew and Late Biblical Hebrew do not represent different chronological periods...

  16. Blind-date Conversation Joining

    Directory of Open Access Journals (Sweden)

    Luca Cesari

    2013-07-01

    Full Text Available We focus on a form of joining conversations among multiple parties in service-oriented applications where a client may asynchronously join an existing conversation without need to know in advance any information about it. More specifically, we show how the correlation mechanism provided by orchestration languages enables a form of conversation joining that is completely transparent to clients and that we call 'blind-date joining'. We provide an implementation of this strategy by using the standard orchestration language WS-BPEL. We then present its formal semantics by resorting to COWS, a process calculus specifically designed for modelling service-oriented applications. We illustrate our approach by means of a simple, but realistic, case study from the online games domain.

  17. The geochemistry characteristic and dating of cold seepage carbonates of the Pearl River Mouth Basin, eastern of South China Sea

    Science.gov (United States)

    Fang, Yunxin; Fu, Shaoying

    2015-04-01

    Cold seepage carbonates are usually formed by the interaction of methane oxidizing archaea, sulfate reducing bacteria and cold seepage which contain abundant venting hydrocarbon gases. The presence of cold seepage carbonates on the seabed is one of the evidences that the area exist venting hydrocarbon gases, which are usually result by the dissociation of gas hydrate. The cold seepage property and fluid flow rate can influence the oxidation-deoxidation environment of the bottom water and sediment. Many previous studies focused on the mineral composition, microstructure, elemental composition, isotope composition of the cold seepage carbonates and isotopic dating for the cold seepage carbonates. The isotopic dating for the cold seepage carbonates can provide the information of the gas hydrate formation and dissociation in some area of the South China Sea. High precision TIMS-U dating and 14C dating are used as routine method for the dating of the Quaternary carbonates and fossils. The cold seepage carbonates in the study include the samples collected by ROV on the seabed and the drilling for gas hydrate in the Pearl River Mouth Basin, eastern of the South China Sea. The authigenic carbonate occurred in different depth in the A, B and C drilling site. They may be represent different events of gas hydrate formation and dissociation in the Quaternary. The dating study for all the cold seepage carbonates can provide the relative accurate eras of the gas hydrate dissociation events in certain area of the South China Sea.

  18. 甘肃拾金坡金矿床成因:来自40Ar/39Ar定年、成矿流体及H-O-S同位素证据%Ore Genesis of the Shijinpo Gold Deposit in Gansu Province, NW China:40Ar/39Ar Dating, Ore-Forming Fluid and H-O-S Isotopes Constrains

    Institute of Scientific and Technical Information of China (English)

    朱江; 吕新彪; 莫亚龙; 曹晓峰; 陈超

    2013-01-01

    , variably coexisting with minor amounts of galena, sphalerite and chalcopyrite. Laser incremental heating 40Ar/39Ar analysis of hydrothermal sericite yields a plateau age of (364. 6 ± 3) Ma (2σ) , which suggests that the gold mineralization took place in the late Devonian period. The comprehensive fluid inclusion study shows that there are three major types of fluid inclusions in the early stage: liquid-rich, gas-rich aqueous and CO2-bearing fluid inclusions, with intermediate homogenization temperature (280 - 325℃) , and low salinity (7. 86%- 9. 21% NaCl eqv). The fluid boiling is evidenced by the co-existence of three types of fluid inclusions with similar homogenization temperatures. There is only liquid-rich aqueous fluid inclusions in the late stage, with hqmogenization temperatures and salinities varying from 160℃ to 230℃ , 9. 47% to 11. 10%Nacl equivalent. Fluid pressures declined from ca. 113 MPa to ca. 11 MPa through the early stage to the late stage, and the ore-forming fluids are assumed to undergo boiling in a transitional setting (from compression to extension). Oxygen and hydrogen isotopic contents in the ore-forming fluid range from 1. 39%o to 3. 39%o and - 71%o to -99%o, respectively, suggesting that the ore-forming fluid was mainly derived from the metamorphic water, and mixed by the meteoric water in the late stage. The measured δ34 S values in sulfide minerals range from 4. 44%o to 11. 33%o. Both the Precambrian metamorphic rock and granitic wall-rock might be the sulfur sources. Based on the paper and the regional geologic data, we conclude that the Shijinpo gold deposit belongs to the orogenic-type gold deposit.

  19. Radiometric dating of quaternary deposits and the hominid mandible of lake banyolas, Spain

    Science.gov (United States)

    Julia, R.; Bischoff, J.L.

    1991-01-01

    We report results of U-series analyses of the travertine matrix surrounding the Banyolas mandible that indicate an age of 45??4 ka bp. The mandible, an archaic hominid fossil generally deemed of mid-Pleistocene age, was recovered from a travertine matrix in 1887. Similar analyses on 21 travertine samples from quarries near the discovery site yield coherent U-series dates in correct stratigraphic order, ranging from 44 ka bp to 117 ka bp. Isotopic composition of these samples and the mandible matrix show no evidence of open system behaviour. Coherent isotopic results from adjacent quarries support the validity of the date on the mandible travertine, and we conclude the mandible is much younger than previously believed. ?? 1991.

  20. Dating samples of lunar soil from the Mare Crisium by the Ar/39/-Ar/40/ technique

    Science.gov (United States)

    Shanin, L. L.; Arakeliants, M. M.; Bogatikov, O. A.; Ivanenko, V. V.; Pupyrev, Iu. G.; Tarasov, L. S.; Frikh-Khar, D. I.

    1981-07-01

    Two samples (dolerite and gabbro fragments) from a depth of 184 cm in the Luna 24 core are dated using the Ar(39)-Ar(40) technique. The values obtained are found to be lower than all published isotopic ages for the Luna 24 samples. An analysis of possible dating errors of the lunar samples, together with the good agreement of the results from the Ar(39)-Ar(40) technique of geochronologic standards and anorthosite from the Korosten pluton with the results from Rb-Sr, U-Pb, and Sm-Nd methods, attests the reliability of the values.

  1. 40 CFR 62.6612 - Effective date.

    Science.gov (United States)

    2010-07-01

    .../medical/infectious Waste Incinerators § 62.6612 Effective date. The effective date for the portion of the plan applicable to existing hospital/medical/infectious waste incinerators is August 21, 2000. Fluoride Emissions From Existing Phosphate Fertilizer Plants...

  2. When you pass your due date

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000515.htm When you pass your due date To use the sharing features ... link between you and your baby. As you pass your due date, the placenta may not work ...

  3. 40 CFR 62.1352 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Existing Municipal Solid Waste Landfills § 62.1352 Effective date. The effective date of the plan for municipal solid waste landfills is September 28, 1998. Air Emissions From Hospital/Medical/Infectious...

  4. 40 CFR 62.11122 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Hospital/medical/infectious Waste Incinerators § 62.11122 Effective date. The effective date for the portion of the plan applicable to existing hospital/medical/infectious waste incinerators is August 21... Tons Per Day of Municipal Solid Waste...

  5. 40 CFR 62.3342 - Effective Date.

    Science.gov (United States)

    2010-07-01

    ... Compounds and Nitrogen Oxide Emissions from Existing Hospital / Medical Infectious Waste Incinerators § 62.3342 Effective Date. The effective date of the Illinois State Plan for existing Hospital/Medical... Day of Municipal Solid Waste...

  6. 40 CFR 62.8602 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Existing Municipal Solid Waste Landfills § 62.8602 Effective date. The effective date of the plan for municipal solid waste landfills is February 13, 1998. Air Emissions From Hospital/Medical/Infectious...

  7. 40 CFR 62.8872 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Municipal Solid Waste Landfills § 62.8872 Effective date. The effective date of the plan for municipal solid waste landfills is October 6, 1998. Emissions From Hospital, Medical, and Infectious Waste...

  8. 40 CFR 62.6602 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Existing Municipal Solid Waste Landfills § 62.6602 Effective date. The effective date of the plan for municipal solid waste landfills is September 8, 1998. Air Emissions From Hospital/Medical/Infectious...

  9. 40 CFR 62.9662 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Hospital/medical/infectious Waste Incinerators (hmiwis) (section 111(d)/129 Plan) § 62.9662 Effective date. The effective date of the plan is June 6, 2000. Emissions From Existing Commercial/Industrial Solid Waste Incineration Units...

  10. GEOCHRONOMETRY&ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20071262 Gong Gelian(Guangzhou Institute of Geochemistry,CAS,Guangzhou 510064, China)Luminescence Dating for Environ- mental Evolution Study in Terrestrial Land, Deep Sea and Coastal Belts:A Review(Ma- rine Geology & Quaternary Geology,ISSN 0256-1492,CN37-1117/P,26(2),2006, p.133-138,2 illus.,34 refs.,with English abstract) Key words:thermoluminescent dating

  11. Stable isotope analysis of precipitation samples obtained via crowdsourcing reveals the spatiotemporal evolution of Superstorm Sandy.

    Directory of Open Access Journals (Sweden)

    Stephen P Good

    Full Text Available Extra-tropical cyclones, such as 2012 Superstorm Sandy, pose a significant climatic threat to the northeastern United Sates, yet prediction of hydrologic and thermodynamic processes within such systems is complicated by their interaction with mid-latitude water patterns as they move poleward. Fortunately, the evolution of these systems is also recorded in the stable isotope ratios of storm-associated precipitation and water vapor, and isotopic analysis provides constraints on difficult-to-observe cyclone dynamics. During Superstorm Sandy, a unique crowdsourced approach enabled 685 precipitation samples to be obtained for oxygen and hydrogen isotopic analysis, constituting the largest isotopic sampling of a synoptic-scale system to date. Isotopically, these waters span an enormous range of values (> 21‰ for δ(18O, > 160‰ for δ(2H and exhibit strong spatiotemporal structure. Low isotope ratios occurred predominantly in the west and south quadrants of the storm, indicating robust isotopic distillation that tracked the intensity of the storm's warm core. Elevated values of deuterium-excess (> 25‰ were found primarily in the New England region after Sandy made landfall. Isotope mass balance calculations and Lagrangian back-trajectory analysis suggest that these samples reflect the moistening of dry continental air entrained from a mid-latitude trough. These results demonstrate the power of rapid-response isotope monitoring to elucidate the structure and dynamics of water cycling within synoptic-scale systems and improve our understanding of storm evolution, hydroclimatological impacts, and paleo-storm proxies.

  12. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface...... deposited during the Early Ordovician — a time of known redox instability in ancient oceans – exhibit a significant positive Cr isotope excursion of +0.5‰. This excursion is interpreted as the reductive drawn down of dissolved Cr in seawater in response to the development of a proximal anoxic sink...... of ancient marine sediments can be a useful tool for understanding the cycling of redox sensitive elements on a local scale....

  13. Isotopic ratios at z=0.68 from molecular absorption lines toward B 0218+357

    CERN Document Server

    Wallstrom, S H J; Guelin, M

    2016-01-01

    Isotopic ratios of heavy elements are a key signature of the nucleosynthesis processes in stellar interiors. The contribution of successive generations of stars to the metal enrichment of the Universe is imprinted on the evolution of isotopic ratios over time. We investigate the isotopic ratios of carbon, nitrogen, oxygen, and sulfur through millimeter molecular absorption lines arising in the z=0.68 absorber toward the blazar B 0218+357. We find that these ratios differ from those observed in the Galactic interstellar medium, but are remarkably close to those in the only other source at intermediate redshift for which isotopic ratios have been measured to date, the z=0.89 absorber in front of PKS1830-211. The isotopic ratios in these two absorbers should reflect enrichment mostly from massive stars, and they are indeed close to the values observed toward local starburst galaxies. Our measurements set constraints on nucleosynthesis and chemical evolution models.

  14. Memory for time: How people date events

    NARCIS (Netherlands)

    S.M.J. Janssen; A.G. Chessa; J.M.J. Murre

    2006-01-01

    The effect of different formats on the accuracy of dating news and the distribution of personal events was examined in four conditions. In the first, participants had to date events in the absolute time format (e.g., "July 2004"), and in the second, they had to date events in the relative time forma

  15. 7 CFR 953.120 - Nomination date.

    Science.gov (United States)

    2010-01-01

    ... STATES Rules and Regulations Change in Date for Completing Nominations, Term of Office, and Fiscal Period § 953.120 Nomination date. The names of committee nominees shall be supplied to the Secretary in such... 7 Agriculture 8 2010-01-01 2010-01-01 false Nomination date. 953.120 Section 953.120...

  16. Dates and Times Made Easy with lubridate

    Directory of Open Access Journals (Sweden)

    Garrett Grolemund

    2011-04-01

    Full Text Available This paper presents the lubridate package for R, which facilitates working with dates and times. Date-times create various technical problems for the data analyst. The paper highlights these problems and oers practical advice on how to solve them using lubridate. The paper also introduces a conceptual framework for arithmetic with date-times in R.

  17. 42 CFR 423.40 - Effective dates.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Effective dates. 423.40 Section 423.40 Public... Effective dates. (a) Initial enrollment period. (1) An enrollment made prior to the month of entitlement to... period specified in § 423.38(c), the effective date is determined by CMS, which, to the...

  18. 40 CFR 469.11 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Compliance dates. 469.11 Section 469... Compliance dates. The compliance deadline for the BAT fluoride limitation shall be as soon as possible as... determined by the permit writer, but in no event later than July 1, 1984. The compliance date for PSES...

  19. 40 CFR 1506.12 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Effective date. 1506.12 Section 1506... Effective date. The effective date of these regulations is July 30, 1979, except that for agencies that... extent practicable to ongoing activities and environmental documents begun before the effective...

  20. 33 CFR 106.110 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Compliance dates. 106.110 Section... MARINE SECURITY: OUTER CONTINENTAL SHELF (OCS) FACILITIES General § 106.110 Compliance dates. (a) On or... TWIC under this part may enroll beginning after the date set by the Coast Guard in a Notice to...

  1. 40 CFR 141.152 - Effective dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Effective dates. 141.152 Section 141...) NATIONAL PRIMARY DRINKING WATER REGULATIONS Consumer Confidence Reports § 141.152 Effective dates. (a) The... 1, 2000, and by April 1 annually thereafter or (2) On a date mutually agreed upon by the seller...

  2. 40 CFR 425.05 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Compliance dates. 425.05 Section 425... STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE CATEGORY General Provisions § 425.05 Compliance dates. The compliance date for new source performance standards (NSPS) and pretreatment standards for...

  3. 75 FR 57252 - Designated Transfer Date

    Science.gov (United States)

    2010-09-20

    ... PROTECTION Designated Transfer Date AGENCY: Bureau of Consumer Financial Protection. ACTION: Notice. SUMMARY... designates July 21, 2011, as the date for the transfer of functions to the Bureau of Consumer Financial Protection (``CFPB''). On this ``designated transfer date,'' certain authorities will transfer from...

  4. 49 CFR 214.305 - Compliance dates.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Compliance dates. 214.305 Section 214.305..., DEPARTMENT OF TRANSPORTATION RAILROAD WORKPLACE SAFETY Roadway Worker Protection § 214.305 Compliance dates. Each program adopted by a railroad shall comply not later than the date specified in the...

  5. 46 CFR 272.44 - Dates.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Dates. 272.44 Section 272.44 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION REGULATIONS AFFECTING SUBSIDIZED VESSELS AND OPERATORS REQUIREMENTS... Examination, Audit, Review and Appeal Procedures § 272.44 Dates. The dates noted on the letters...

  6. 18 CFR 1308.7 - Effective date.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Effective date. 1308.7... General Matters § 1308.7 Effective date. Subject to § 1308.3(a), this part applies to any TVA contract having an effective date on or after March 1, 1979....

  7. 29 CFR 452.137 - Effective dates.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 2 2010-07-01 2010-07-01 false Effective dates. 452.137 Section 452.137 Labor Regulations Relating to Labor OFFICE OF LABOR-MANAGEMENT STANDARDS, DEPARTMENT OF LABOR LABOR-MANAGEMENT STANDARDS... OF 1959 Dates and Scope of Application § 452.137 Effective dates. (a) Section 404 states when...

  8. 36 CFR 1258.16 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Effective date. 1258.16... AVAILABILITY AND USE FEES § 1258.16 Effective date. The fees in this part are effective on October 1, 2007. If your order was received by NARA before this effective date, we will charge the fees in effect at...

  9. 40 CFR 141.6 - Effective dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Effective dates. 141.6 Section 141.6... PRIMARY DRINKING WATER REGULATIONS General § 141.6 Effective dates. (a) Except as provided in paragraphs...) shall take effect 2 years after the date of promulgation of these regulations for community...

  10. 31 CFR 575.212 - Effective dates.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective dates. 575.212 Section 575.212 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... Effective dates. The effective dates of the prohibitions and directives contained in this subpart B are...

  11. 31 CFR 540.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 540.302 Section 540.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... REGULATIONS General Definitions § 540.302 Effective date. The term effective date refers to the effective...

  12. 38 CFR 8a.3 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Effective date. 8a.3... INSURANCE § 8a.3 Effective date. (a) Where the grant was approved prior to August 11, 1971, VMLI shall be effective August 11, 1971, if on that date, the eligible veteran was obligated under a mortgage loan,...

  13. 33 CFR 105.115 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Compliance dates. 105.115 Section... MARITIME SECURITY: FACILITIES General § 105.115 Compliance dates. (a) On or before December 31, 2003... required to obtain a TWIC under this part may enroll beginning after the date set by the Coast Guard in...

  14. 34 CFR 105.42 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Effective date. 105.42 Section 105.42 Education Regulations of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION... DEPARTMENT OF EDUCATION § 105.42 Effective date. The effective date of this part is October 9, 1990....

  15. 7 CFR 1000.90 - Dates.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 9 2010-01-01 2009-01-01 true Dates. 1000.90 Section 1000.90 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and... Miscellaneous Provisions § 1000.90 Dates. If a date required for a payment contained in a Federal milk...

  16. 7 CFR 1421.101 - Maturity dates.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Maturity dates. 1421.101 Section 1421.101 Agriculture... Maturity dates. (a)(1) All marketing assistance loans shall mature on demand by CCC and no later than the... filed and disbursed except, for transferred marketing assistance loan collateral. The maturity date...

  17. 49 CFR 1150.13 - Relevant dates.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 8 2010-10-01 2010-10-01 false Relevant dates. 1150.13 Section 1150.13 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION BOARD, DEPARTMENT... Designated Operators § 1150.13 Relevant dates. The exact dates of the period of operation which have...

  18. 40 CFR 57.106 - Expiration date.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Expiration date. 57.106 Section 57.106 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PRIMARY NONFERROUS SMELTER ORDERS General § 57.106 Expiration date. Each NSO shall state its expiration date. No...

  19. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    <正>20050934 Chen Zhihong (Chinese Academy of Geological Sciences, Beijing 100037, China); Lu Songnian Age of the Fushui Intermediate-Mafic Intrusive Complex in the Qinling Orogen, New Zircon U - Pb and Whole -Rock Sm and Nd Isotope Chronological Evidence (Geological Bulletin of China, ISSN 1671-2552, CN11-4648/P, 23(4), 2004, p. 322-328, 3 illus. , 3 tables, 10 refs. )

  20. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  1. Nuclear physics and stable isotopes; Physique nucleaire et isotopes stables

    Energy Technology Data Exchange (ETDEWEB)

    Goutte, D. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee

    1994-12-31

    The aim of this paper is to show that fundamental research in nuclear physics requires utilization of stable isotopes; stable isotopes are essential as target material since a large quantity of nucleus have to be studied in order to appreciate all the complexity of the nuclear structure, but also as a tool, such as beams, for the same purpose. Examples are given with samarium, tin and germanium isotopes. 7 figs.

  2. Two 1999 Dates Worth Noting

    Science.gov (United States)

    Stern, David P.

    1999-01-01

    Two dates in 1999 can serve as pivots for space-related educational outreach. On August 11 a total solar eclipse will sweep across Europe and also across the Near East, where it will come remarkably close to matching the ancient eclipse (probably in 129 BC) used by Hipparchus to estimate the distance of the Moon. Using published eclipse data, students may conduct a similar calculation for 1999 and in the process obtain insights about astronomy, history and the way scientists work. October 19, 1999 will be the 100th anniversary of the day when a teen-age Robert Goddard climbed a cherry tree near the Worcester home where his family was staying, intending to prune it. Sitting in that tree, Goddard began daydreaming about space flight, and by the time he came down he had resolved to dedicate his life to implementing that dream. He later marked that day as "Anniversary day," a personal holiday. Material on both subjects can be reached from http://www-spof.gsfc.nasa.gov/stargaze/Sintro.htm, sections 8a and 26. The section on Goddard includes his experiments with a ballistic pendulum and the DeLaval nozzle, which laid the essential scientific foundation of spaceflight and which is also suitable for classroom presentation.

  3. Hvad Luther kan lære os i en tid med konkurrencestat

    DEFF Research Database (Denmark)

    Østergaard, Uffe

    2016-01-01

    Anmeldelse af: Fra Luther til konkurrencestaten / af Jørn Henrik Petersen. Syddansk Universitetsforlag, 2016. 315 sider......Anmeldelse af: Fra Luther til konkurrencestaten / af Jørn Henrik Petersen. Syddansk Universitetsforlag, 2016. 315 sider...

  4. Calcium isotope ratios in animal and human bone

    Science.gov (United States)

    Reynard, L. M.; Henderson, G. M.; Hedges, R. E. M.

    2010-07-01

    Calcium isotopes in tissues are thought to be influenced by an individual's diet, reflecting parameters such as trophic level and dairy consumption, but this has not been carefully assessed. We report the calcium isotope ratios (δ 44/42Ca) of modern and archaeological animal and human bone ( n = 216). Modern sheep raised at the same location show 0.14 ± 0.08‰ higher δ 44/42Ca in females than in males, which we attribute to lactation by the ewes. In the archaeological bone samples the calcium isotope ratios of the herbivorous fauna vary by location. At a single site, the archaeological fauna do not show a trophic level effect. Humans have lower δ 44/42Ca than the mean site fauna by 0.22 ± 0.22‰, and the humans have a greater δ 44/42Ca range than the animals. No effect of sex or age on the calcium isotope ratios was found, and intra-individual skeletal δ 44/42Ca variability is negligible. We rule out dairy consumption as the main cause of the lower human δ 44/42Ca, based on results from sites pre-dating animal domestication and dairy availability, and suggest instead that individual physiology and calcium intake may be important in determining bone calcium isotope ratios.

  5. A proposed standard on medical isotope production in fission reactors

    Energy Technology Data Exchange (ETDEWEB)

    Schenter, R. E. [Smart Bullets Inc., 2521 SW Luradel Street, Portland, OR 97219 (United States); Brown, G. J. [Ozarks Medical Center, Cancer Treatment Center, Shaw Medical Building, 1111 Kentucky Avenue, West Plains, MO 65775 (United States); Holden, C. S. [Thorenco LLC, 369 Pine Street, San Francisco, CA 94104 (United States)

    2006-07-01

    Authors Robert E. Sehenter, Garry Brown and Charles S. Holden argue that a Standard for 'Medical Isotope Production' is needed. Medical isotopes are becoming major components of application for the diagnosis and treatment of all the major diseases including all forms of cancer, heart disease, arthritis, Alzheimer's, among others. Current nuclear data to perform calculations is incomplete, dated or imprecise or otherwise flawed for many isotopes that could have significant applications in medicine. Improved data files will assist computational analyses to design means and methods for improved isotope production techniques in the fission reactor systems. Initial focus of the Standard is expected to be on neutron cross section and branching data for both fast and thermal reactor systems. Evaluated and reviewed tables giving thermal capture cross sections and resonance integrals for the major target and product medical isotopes would be the expected 'first start' for the 'Standard Working Group'. (authors)

  6. Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records

    Science.gov (United States)

    Klemm, Veronika; Frank, Martin; Levasseur, Sylvain; Halliday, Alex N.; Hein, James R.

    2008-08-01

    Three ferromanganese crusts from the northeast, northwest and central Atlantic were re-dated using osmium (Os) isotope stratigraphy and yield ages from middle Miocene to the present. The three Os isotope records do not show evidence for growth hiatuses. The reconstructed Os isotope-based growth rates for the sections older than 10 Ma are higher than those determined previously by the combined beryllium isotope (10Be/9Be) and cobalt (Co) constant-flux methods, which results in a decrease in the maximum age of each crust. This re-dating does not lead to significant changes to the interpretation of previously determined radiogenic isotope neodymium, lead (Nd, Pb) time series because the variability of these isotopes was very small in the records of the three crusts prior to 10 Ma. The Os isotope record of the central Atlantic crust shows a pronounced minimum during the middle Miocene between 15 and 12 Ma, similar to a minimum previously observed in two ferromanganese crusts from the central Pacific. For the other two Atlantic crusts, the Os isotope records and their calibration to the global seawater curve for the middle Miocene are either more uncertain or too short and thus do not allow for a reliable identification of an isotopic minimum. Similar to pronounced minima reported previously for the Cretaceous/Tertiary and Eocene/Oligocene boundaries, possible interpretations for the newly identified middle Miocene Os isotope minimum include changes in weathering intensity and/or a meteorite impact coinciding with the formation of the Nördlinger Ries Crater. It is suggested that the eruption and weathering of the Columbia River flood basalts provided a significant amount of the unradiogenic Os required to produce the middle Miocene minimum.

  7. Nickel isotopes and methanogens

    Science.gov (United States)

    Neubeck, A.; Ivarsson, M.

    2013-12-01

    Methanogens require Ni for their growth and as a consequence the microbial fractionation of Ni isotopes can be used as a biomarker for activity of methanogenic communities1. Anaerobic laboratory experiments was performed using methanogens to investigate methanogenic growth in a modified nutrient media2 with olivine Fo91 (5g/l) added as an additional mineral nutrient source and as the only H2 provider. One of the investigated methanogens showed an increased growth in the experiments with added olivine. There were also a close relationship between the mobilized Ni and the growth of the methanogen. Ni is an element that previously has been neglected in the study of fossilized microorganisms and their interaction with mineral substrates and, thus, there are no records or published data of Ni in association with microfossils. However, we have detected enrichments of Ni in fossilized microorganisms and ichno-fossils, respectively, from three separate locations. Ni is not present in the host rock in any of the samples. Thus, Ni is present in association with fossilized microorganisms from environments and more extensive analysis is required to understand the magnitude, uptake, preservation and fractionation of Ni in microfossils. In order to analyze Ni isotope fractionation from microbe-mineral interaction, we plan to use a high-resolution Laser-Ablation Time-of-Flight Mass Spectrometer (LMS)3. In situ profile ablation will provide detailed and localized data on fractionation patterns between microfossils and their host rock. Also, this technique will allow us to identify the change in Ni isotopic fractionation in rock samples caused by abiotic and biogenic processes in a faster and easier way and with less risk for contamination compared to the wet chemistry analyses of Ni isotopes. 1. Cameron, V., Vance, D., Archer, C. & House, C. H. A biomarker based on the stable isotopes of nickel. Proceedings of the National Academy of Sciences 106, 10944-10948 (2009). 2. Schn

  8. Therapeutic use of radioactive isotopes

    CERN Multimedia

    Caroline Duc

    2013-01-01

    In December, researchers from ISOLDE-CERN, the Paul Scherrer Institute (PSI) and the Institut Laue-Langevin (ILL) published the results of an in vivo study which successfully proved the effectiveness of four terbium isotopes for diagnosing and treating cancerous tumours.   Four terbium isotopes suitable for clinical purposes. “ISOLDE is the only installation capable of supplying terbium isotopes of such purity and intensity in the case of three out of the four types used in this study,” explains Karl Johnson, a physicist at ISOLDE.  “Producing over a thousand different isotopes, our equipment offers the widest choice of isotopes in the world!” Initially intended for fundamental physics research, ISOLDE has diversified its activities over time to invest in various projects in the materials science, biochemistry and nuclear medicine fields. The proof-of-concept study has confirmed that the four terbium isotopes 149Tb, 152Tb, 155Tb produ...

  9. IRSL dating of Middle Pleistocene interglacial sediments from southern Quebec (Canada) using multiple and single grain aliquots

    Science.gov (United States)

    Balescu, S.; Lamothe, M.; Auclair, M.; Shilts, W.W.

    2001-01-01

    The IRSL dating of Middle Pleistocene interglacial fluvial sediments from Southern Quebec, correlated with oxygen isotopic stage 7, yields optical dates much younger than the expected geological age. Single grain IRSL measurements on alkali-feldspars, following the fadia protocol developed by Lamothe and Auclair (Earth and Planetary Science Letters, 171, 319-323, 1999), suggest that anomalous fading is the most probable cause for this severe age underestimation. The IRSL dates corrected for this anomalous fading are in better agreement with the expected ages. ?? 2000 Elsevier Science Ltd.

  10. Carbon Isotope Measurements of Experimentally-Derived Hydrothermal Mineral-Catalyzed Organic Products by Pyrolysis-Isotope Ratio Mass Spectrometry

    Science.gov (United States)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.

    2011-01-01

    We report results of experiments to measure the C isotope composition of mineral catalyzed organic compounds derived from high temperature and high pressure synthesis. These experiments make use of an innovative pyrolysis technique designed to extract and measure C isotopes. To date, our experiments have focused on the pyrolysis and C isotope ratio measurements of low-molecular weight intermediary hydrocarbons (organic acids and alcohols) and serve as a proof of concept for making C and H isotope measurements on more complicated mixtures of solid-phase hydrocarbons and intermediary products produced during high temperature and high pressure synthesis on mineral-catalyzed surfaces. The impetus for this work stems from recently reported observations of methane detected within the Martian atmosphere [1-4], coupled with evidence showing extensive water-rock interaction during Martian history [5-7]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization reactions [8,9]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [10-12]. Further, recent experiments by Fu et al. [13] focus on examining detailed C isotope measurements of hydrocarbons produced by surface-catalyzed mineral reactions. Work described in this paper details the experimental techniques used to measure intermediary organic reaction products (alcohols and organic acids).

  11. Lithium isotope separation by laser

    Energy Technology Data Exchange (ETDEWEB)

    Arisawa, T.; Maruyama, Y.; Suzuki, Y.; Shiba, K.

    1982-01-01

    A lithium isotope separation was performed using a laser isotope separation method. It was found that the lithium atoms with a natural isotopic abundance enhanced its /sup 6/Li concentration up to over 90% by tuning the laser wavelength to the /sup 2/Psub(1/2) of /sup 6/Li. Too high power, however, leads to a loss of enrichment due to the power broadening effect which was analysed by the equation of motion of density matrices.

  12. Enhanced recycling of organic matter and Os-isotopic evidence for multiple magmatic or meteoritic inputs to the Late Permian Panthalassic Ocean, Opal Creek, Canada

    Science.gov (United States)

    Georgiev, Svetoslav V.; Stein, Holly J.; Hannah, Judith L.; Henderson, Charles M.; Algeo, Thomas J.

    2015-02-01

    The geochemical record for the Permian-Triassic boundary in northern latitudes is essential to evaluation of global changes associated with the most profound extinction of life on Earth. We present inorganic and organic geochemical data, and Re-Os isotope systematics in a critical stratigraphic interval of pre- and post-extinction Upper Permian-Lower Triassic sediments from Opal Creek, western Canada (paleolatitude of ∼30°N). We document significant and long-lived changes in Panthalassa seawater chemistry that were initiated during the first of four magmatic or meteoritic inputs to Late Permian seawater, evidenced by notable decreases of Os isotopic ratios upsection. Geochemical signals indicate establishment of anoxic bottom waters shortly after regional transgression reinitiated sedimentation in the Late Permian. Euxinic signals are most prominent in the Upper Permian sediments with low organic carbon and high sulfur contents, and gradually wane in the Lower Triassic. The observed features may have been generated in a strongly euxinic ocean in which high bacterioplankton productivity sustained prolific microbial sulfate reduction in the sediment and/or water column, providing hydrogen sulfide to form pyrite. This scenario requires nearly complete anaerobic decomposition of predominantly labile marine organic matter (OM) without the necessity for a complete collapse of primary marine productivity. Similar geochemical variations could have been achieved by widespread oxidation of methane by sulfate reducers after a methanogenic burst in the Late Permian. Both scenarios could have provided similar kill mechanisms for the latest Permian mass extinction. Despite the moderate thermal maturity of the section, OM in all studied samples is dominantly terrestrial and/or continentally derived, recycled and refractory ancient OM. We argue that, as such, the quantity of the OM in the section mainly reflects changes in terrestrial vegetation and/or weathering, and not in

  13. Nitrogen isotopes in Tree-Rings - An approach combining soil biogeochemistry and isotopic long series with statistical modeling

    Science.gov (United States)

    Savard, Martine M.; Bégin, Christian; Paré, David; Marion, Joëlle; Laganière, Jérôme; Séguin, Armand; Stefani, Franck; Smirnoff, Anna

    2016-04-01

    Monitoring atmospheric emissions from industrial centers in North America generally started less than 25 years ago. To compensate for the lack of monitoring, previous investigations have interpreted tree-ring N changes using the known chronology of human activities, without facing the challenge of separating climatic effects from potential anthropogenic impacts. Here we document such an attempt conducted in the oil sands (OS) mining region of Northeastern Alberta, Canada. The reactive nitrogen (Nr)-emitting oil extraction operations began in 1967, but air quality measurements were only initiated in 1997. To investigate if the beginning and intensification of OS operations induced changes in the forest N-cycle, we sampled white spruce (Picea glauca (Moench) Voss) stands located at various distances from the main mining area, and receiving low, but different N deposition. Our approach combines soil biogeochemical and metagenomic characterization with long, well dated, tree-ring isotopic series. To objectively delineate the natural N isotopic behaviour in trees, we have characterized tree-ring N isotope (15N/14N) ratios between 1880 and 2009, used statistical analyses of the isotopic values and local climatic parameters of the pre-mining period to calibrate response functions and project the isotopic responses to climate during the extraction period. During that period, the measured series depart negatively from the projected natural trends. In addition, these long-term negative isotopic trends are better reproduced by multiple-regression models combining climatic parameters with the proxy for regional mining Nr emissions. These negative isotopic trends point towards changes in the forest soil biogeochemical N cycle. The biogeochemical data and ultimate soil mechanisms responsible for such changes will be discussed during the presentation.

  14. Dating of Pliocene Colorado River sediments: Implications for cosmogenic burial dating and the evolution of the lower Colorado River

    Science.gov (United States)

    Howard, Keith A.; Matmon, Ari; Stock, Greg M.; Granger, Darryl E.

    2017-01-01

    We applied cosmogenic 26Al/10Be burial dating to sedimentary deposits of the ancestral Colorado River. We compared cosmogenic burial ages of sediments to the age of an independently well-dated overlying basalt flow at one site, and also applied cosmogenic burial dating to sediments with less precise independent age constraints. All dated gravels yielded old ages that suggest several episodes of sediment burial over the past ∼5.3 m.y. Comparison of burial ages to the overlying 4.4 Ma basalt yielded good agreement and suggests that under the most favorable conditions, cosmogenic burial dating can extend back 4–5 m.y. In contrast, results from other sites with more broadly independent age constraints highlight the complexities inherent in burial dating; these complexities arise from unknown and complicated burial histories, insufficient shielding, postburial production of cosmogenic isotopes by muons, and unknown initial 26Al/10Be ratios. Nevertheless, and in spite of the large range of burial ages and large uncertainties, we identify samples that provide reasonable burial age constraints on the depositional history of sediment along the lower ancestral Colorado River. These samples suggest possible sediment deposition and burial at ca. 5.3, 4.7, and 3.6 Ma.Our calculated basinwide erosion rate for sediment transported by the modern Colorado River (∼187 mm k.y.−1) is higher than the modern erosion rates inferred from the historic sediment load (80–100 mm k.y.−1). In contrast, basinwide paleo-erosion rates calculated from Pliocene sediments are all under 40 mm k.y.−1 The comparatively lower denudation rates calculated for the Pliocene sediment samples are surprising given that the sampled time intervals include significant Pliocene aggradation and may include much incision of the Grand Canyon and its tributaries. This conflict may arise from extensive storage of sediment along the route of the Colorado River, slower paleobedrock erosion, or the

  15. Dating of Pliocene Colorado River sediments: implications for cosmogenic burial dating and the evolution of the lower Colorado River

    Science.gov (United States)

    Matmon, Ari; Stock, Greg M.; Granger, Darryl E.; Howard, Keith A.

    2011-01-01

    We applied cosmogenic 26Al/10Be burial dating to sedimentary deposits of the ancestral Colorado River. We compared cosmogenic burial ages of sediments to the age of an independently well-dated overlying basalt flow at one site, and also applied cosmogenic burial dating to sediments with less precise independent age constraints. All dated gravels yielded old ages that suggest several episodes of sediment burial over the past ∼5.3 m.y. Comparison of burial ages to the overlying 4.4 Ma basalt yielded good agreement and suggests that under the most favorable conditions, cosmogenic burial dating can extend back 4–5 m.y. In contrast, results from other sites with more broadly independent age constraints highlight the complexities inherent in burial dating; these complexities arise from unknown and complicated burial histories, insufficient shielding, postburial production of cosmogenic isotopes by muons, and unknown initial 26Al/10Be ratios. Nevertheless, and in spite of the large range of burial ages and large uncertainties, we identify samples that provide reasonable burial age constraints on the depositional history of sediment along the lower ancestral Colorado River. These samples suggest possible sediment deposition and burial at ca. 5.3, 4.7, and 3.6 Ma. Our calculated basinwide erosion rate for sediment transported by the modern Colorado River (∼187 mm k.y.−1) is higher than the modern erosion rates inferred from the historic sediment load (80–100 mm k.y.−1). In contrast, basinwide paleo-erosion rates calculated from Pliocene sediments are all under 40 mm k.y.−1 The comparatively lower denudation rates calculated for the Pliocene sediment samples are surprising given that the sampled time intervals include significant Pliocene aggradation and may include much incision of the Grand Canyon and its tributaries. This conflict may arise from extensive storage of sediment along the route of the Colorado River, slower paleobedrock erosion, or the inclusion

  16. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20140393Liu Chunru(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing100029,China);Yin Gongming Research Progress of the Resetting Features of Quartz ESR Signal(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(1),2013,p.24-30,3illus.,59refs.)Key words:ESR dating Electron Spin Resonance(ESR)has been becoming one of the key methods of Quaternary Geochronology with wide range of dating,

  17. Correlates of cyber dating abuse among teens.

    Science.gov (United States)

    Zweig, Janine M; Lachman, Pamela; Yahner, Jennifer; Dank, Meredith

    2014-08-01

    Recent advancements in technology (e.g., social networking, texting) have created new ways for dating youth to relate to one another, including in abusive ways via "cyber dating abuse." Cyber dating abuse is a form of teen dating violence that overlaps with other types of abuse (e.g., psychological) but also has several unique characteristics. Given the phenomenon's limited presence in dating violence literature, we focus on identifying how experiencing cyber dating abuse relates to youths' individual behaviors and experiences (e.g., substance use, sexual activity), psychosocial adjustment, school connection, family relationships, and partner relationships. A total of 3,745 youth (52% female, 74% White) in three northeastern states participated in the survey and reported currently being in a dating relationship or having been in one during the prior year. We found that experiences of cyber dating abuse were most significantly correlated with being female, committing a greater variety of delinquent behaviors, having had sexual activity in one's lifetime, having higher levels of depressive symptoms, and having higher levels of anger/hostility. Further, cyber dating abuse appeared somewhat more strongly related to depressive symptoms and delinquency than did other forms of teen dating violence and abuse.

  18. Fluvial terrace dating using in situ cosmogenic {sup 21}Ne

    Energy Technology Data Exchange (ETDEWEB)

    Sexton, E. [Univ. of Illinois, Chicago, IL (United States); Caffee, M. [Lawrence Livermore National Lab., CA (United States)

    1994-12-01

    Through the analysis of cosmic-ray produced radio-genic and stable nuclide concentrations, specifically {sup 21}Ne, we hope to date certain geomorphic features located along the tributaries of the Colorado River in the Eastern Grand Canyon and the Rainbow Plateau located in Utah. During the Quaternary, the Colorado River system was fed by glacial melting and run-off from the Wind River and Colorado Mountain Ranges. Past periods of aggradation allowed the emplacement of terrace features from debris flow activity. By dating such features we can further constrain the timing of key events such as river down cutting, terrace genesis/exposure age, and rates of surface erosion. Knowing the age and elevation of each terrace we can determine an average rate of down cutting of this river system. This, in turn, will offer information regarding alpine glaciation which is a sensitive indicator of global climate change. Studying the relative concentrations of these isotopic species in surface rocks can be useful in researching glacial periodicity and the relationship between solar activity and climate.

  19. A new regional group of the lower paleolithic in Brittany (France), recently dated by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Monnier, J.L.; Hinguant, S.; Gebhardt, A.; Marguerie, D.; Molines, N.; Morzadec, H. (Rennes-1 Univ., 35 (France)); Hallegouet, B. (Brest Univ., 29 (France)); Laurent, M.; Auguste, P.; Bahain, J.J.; Falgueres, C.; Yokoyama, Y. (Institut de Paleontologie, 75 - Paris (France))

    1994-07-07

    ESR dates obtained at Menez-Dregan 1 (Brittany, France) focus interest on this Lower Paleolithic site and demonstrate that the preserved anthropic combustion structures are among the oldest known in the world. It allows the dating not only of the little known 'Colombanian Group' (it is an 'archaic' original group characterized by many choppers and very few handaxes, different from the Acheulian), but also, for the first time, of the old beaches on the southern coast of Brittany. Preserved bone remains are also very infrequent in Palaeolithic sites of Western France. The dating of the paleolithic layer at the top of the third fossil beach can be connected with isotopic stage 11 or the beginning of isotopic stage 10; it shows that the age of the geological and archaeological layers of Menez-Dregan 1 is probably between 350.000 and 500.000 years.

  20. REIMEP-22 inter-laboratory comparison. ''U Age Dating - determination of the production date of a uranium certified test sample''

    Energy Technology Data Exchange (ETDEWEB)

    Venchiarutti, Celia; Richter, Stephan; Jakopic, Rozle; Aregbe, Yetunde [European Commission, Joint Research Centre (JRC), Geel (Belgium). Institute for Reference Materials and Measurements (IRMM); Varga, Zsolt; Mayer, Klaus [European Commission, Joint Research Centre (JRC), Karlsruhe (Germany). Institute for Transuranium Elements (ITU)

    2015-07-01

    The REIMEP-22 inter-laboratory comparison aimed at determining the production date of a uranium certified test sample (i.e. the last chemical separation date of the material). Participants in REIMEP-22 on ''U Age Dating - Determination of the production date of a uranium certified test sample'' received one low-enriched 20 mg uranium sample for mass spectrometry measurements and/or one 50 mg uranium sample for a-spectrometry measurements, with an undisclosed value for the production date. They were asked to report the isotope amount ratios n({sup 230}Th)/n({sup 234}U) for the 20 mg uranium sample and/or the activity ratios A({sup 230}Th)/A({sup 234}U) for the 50 mg uranium sample in addition to the calculated production date of the certified test samples with its uncertainty. Reporting of the {sup 231}Pa/{sup 235}U ratio and the respective calculated production date was optional. Eleven laboratories reported results in REIMEP-22. Two of them reported results for both the 20 mg and 50 mg uranium certified test samples. The measurement capability of the participants was assessed against the independent REIMEP-22 reference value by means of z- and zeta-scores in compliance with ISO 13528:2005. Furthermore a performance assessment criterion for acceptable uncertainty was applied to evaluate the participants' results. In general, the REIMEP-22 participants' results were satisfactory. This confirms the analytical capabilities of laboratories to determine accurately the age of uranium materials with low amount of ingrown thorium (young certified test sample). The Joint Research Centre of the European Commission (EC-JRC) organised REIMEP-22 in parallel to the preparation and certification of a uranium reference material certified for the production date (IRMM-1000a and IRMM-1000b).

  1. Cold regions isotope applications

    Energy Technology Data Exchange (ETDEWEB)

    Perrigo, L.D.; Divine, T.E.

    1976-04-01

    Pacific Northwest Laboratories (PNL) started the Cold Regions Isotope Applications Program in FY-1975 to identify special conditions in the Arctic and similar geographic areas (Cold Regions) where radioisotope power, heater, or sterilization systems would be desirable and economically viable. Significant progress was made in the first year of this program and all objectives for this initial 12-month period were achieved. The major conclusions and recommendations resulting for this effort are described below. The areas of interest covered include: radiosterilization of sewage; heating of septic tanks; and radioisotope thermoelectric generators as power sources for meteorological instruments and navigational aids. (TFD)

  2. Peridotite xenoliths from the Polynesian Austral and Samoa hotspots: Implications for the destruction of ancient 187Os and 142Nd isotopic domains and the preservation of Hadean 129Xe in the modern convecting mantle

    Science.gov (United States)

    Jackson, M. G.; Shirey, S. B.; Hauri, E. H.; Kurz, M. D.; Rizo, H.

    2016-07-01

    The Re-Os systematics in 13 peridotite xenoliths hosted in young (<0.39 myr) rejuvenated lavas from the Samoan island of Savai'i and 8 peridotite xenoliths from 6 to 10 myr old lavas from the Austral island of Tubuai have been examined to evaluate the history of the oceanic mantle in this region. Modal mineralogy, trace element compositions and 187Os/188Os ratios suggest that these peridotites are not cognate or residual to mantle plumes but rather samples of Pacific oceanic lithosphere created at the ridge. Savai'i and Tubuai islands lie along a flow line in the Pacific plate, and provide two snapshots (separated by over 40 Ma in time) of Pacific mantle that originated in the same region of the East Pacific rise. Tubuai xenoliths exhibit 187Os/188Os from 0.1163 to 0.1304, and Savai'i (Samoa) xenoliths span a smaller range from 0.1173 to 0.1284. The 187Os/188Os ratios measured in Tubuai xenoliths are lower than (and show no overlap with) basalts from Tubuai. The 187Os/188Os of the Savai'i xenoliths overlap the isotopic compositions of lavas from the island of Savai'i, but also extend to lower 187Os/188Os than the lavas. 3He/4He measurements of a subset of the xenoliths range from 2.5 to 6.4 Ra for Tubuai and 10.8 to 12.4 Ra for Savai'i. Like abyssal peridotites and xenoliths from oceanic hotspots that sample the convecting mantle, Os isotopes from the Savai'i and Tubuai xenolith suites are relatively unradiogenic, but do not preserve a record of depleted early-formed (Hadean and Archean) mantle domains expected from earlier cycles of ridge-related depletion, continent extraction, or subcontinental lithospheric mantle erosion. The lack of preservation of early-formed, geochemically-depleted Os-isotopic and 142Nd/144Nd domains in the modern convecting mantle contrasts with the preservation of early-formed (early-Hadean) 129Xe/130Xe isotopic heterogeneities in the convecting mantle. This can be explained if the initial isotopic signatures in Re-Os and Sm-Nd systems

  3. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>20081140 Cheng Peng(State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,CAS,Xi’an 710075,China);Zhou Weijian Advances in Radiocarbon Dating Researches in the Loess-Paleosol Sequences(Marine Geology & Quaternary Geology,ISSN0256-1492,CN37-

  4. 40 CFR 156.159 - Compliance date.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Compliance date. 156.159 Section 156... REQUIREMENTS FOR PESTICIDES AND DEVICES Container Labeling § 156.159 Compliance date. Any pesticide product...(d)(7), 156.10(f), 156.10(i)(2)(ix), 156.140, 156.144, 156.146, and 156.156. Effective Date Note:...

  5. Conventional U-Pb dating versus SHRIMP of the Santa Barbara Granite Massif, Rondonia, Brazil

    Science.gov (United States)

    Sparrenberger, I.; Bettencourt, Jorge S.; Tosdal, R.M.; Wooden, J.L.

    2002-01-01

    The Santa Ba??rbara Granite Massif is part of the Younger Granites of Rondo??nia (998 - 974 Ma) and is included in the Rondo??nia Tin Province (SW Amazonian Craton). It comprises three highly fractionated metaluminous to peraluminous within-plate A-type granite units emplaced in older medium-grade metamorphic rocks. Sn-mineralization is closely associated with the late-stage unit. U-Pb monazite conventional dating of the early-stage Serra do Cicero facies and late-stage Serra Azul facies yielded ages of 993 ?? 5 Ma and 989 ?? 13 Ma, respectively. Conventional multigrain U-Pb isotope analyses of zircon demonstrate isotopic disturbance (discordance) and the preservation of inherited older zircons of several different ages and thus yield little about the ages of Sn-granite magmatism. SHRIMP U-Pb ages for the Santa Ba??rbara facies association yielded a 207Pb/206Pb weighted-mean age of 978 ?? 13 Ma. The textural complexity of the zircon crystals of the Santa Ba??rbara facies association, the variable concentrations of U, Th and Pb, as well as the mixed inheritance of zircon populations are major obstacles to using conventional multigrain U-Pb isotopic analyses. Sm-Nd model ages and ??Nd (T) values reveal anomalous isotopic data, attesting to the complex isotopic behaviour within these highly fractionated granites. Thus, SHRIMP U-Pb zircon and conventional U-Pb monazite dating methods are the most appropriate to constrain the crystallization age of the Sn-bearing granite systems in the Rondo??nia Tin Province.

  6. Biomarker isotope and soil tetraether records of the paleotopographic and paleoenvironmental history of the SE margin of Tibet

    Science.gov (United States)

    Hren, M. T.; Hoke, G. D.; Garzione, C. N.; Liu, J.

    2015-12-01

    Paleotopographic information is critical for evaluating geodynamic models and separating effects of climatic and tectonic change in sedimentary records. Compound-specific hydrogen isotopes of plant waxes and soil tetraethers provide a novel means of constraining changes in elevation through time for a diverse range of paleoenvironments. Recent stable isotopic data from paleosol and lacustrine carbonate from basins along the SE margin of the Tibetan plateau indicate carbonates formed from isotopically depleted waters. These are interpreted to reflect longstanding high topography with regional uplift contemporaneous with Paleogene faulting along the Alio Shan - Red River shear zone. Here, hydrogen isotopes of modern plant waxes and soil tetraether temperatures from modern soils in China's Yunnan province are used to calibrate a multiproxy temperature and isotopic approach to evaluate the paleoelevation and paleoclimatic history of the SE margin of the Tibetan plateau. Modern organic molecular data are paired with plant wax hydrogen isotopes and tetraether temperatures from sediments along the SE plateau margin that date from Eocene to Pliocene to evaluate temperature and isotopic change that may be related to uplift. Organic molecular data show large temperature and isotopic gradients from the late Eocene to Pliocene. These data suggest longstanding high topography and minimal post-Miocene uplift due to lower crustal flow. However, stable isotopic and paleotemperature data must be reconciled with geomorphic evidence for post-Miocene changes in incision rates and model predictions of changing climate and isotopic lapse rates.

  7. Research on genetics of rice heading date

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Heading date is one of the most important traits for rice adaptation to cultivation area and crop seasons, and it is mainly determined by photoperiod, basic vegetative growth, and temperature of cultivars. The diversity of combinations of photo-sensitive varieties and the basic vegetative, makes the heading date varied. On one hand, this supplies abundant resources for different ecotypes breeding; on the other hand, it complicates the inheritance of heading date. In recent years, transgression of late maturity has often been encountered, especially between indica and japonica subspecies, this had inhabited the use of hybrid vigor. Therefore, understanding the inheritance basis of heading date is very important for breeding practices.

  8. Si Isotopes of Brownleeite

    Science.gov (United States)

    Nakamura-Messenger, K.; Messenger, Scott R.; Ito, M.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Tatsuoka, H.; Zolensky, M. E.; Tatsuoka, H.

    2010-01-01

    Brownleeite is a manganese silicide, ideally stoichiometric MnSi, not previously observed in nature until its discovery within an interplanetary dust particle (IDP) that likely originated from a comet [1]. Three discrete brownleeite grains in the IDP L2055 I3 (4 microns in size, hereafter IDP I3) were identified with maximum dimensions of 100, 250 and 600 nm and fully analyzed using scanning-transmission electron microscopy (STEM) [1]. One of the grains (100 nm in size) was poikilitically enclosed by low-Fe, Mn-enriched (LIME) olivine. LIME olivine is epitaxial to the brownleeite with the brownleeite (200) parallel to the olivine c* [1]. LIME olivine is an enigmatic phase first reported from chondritic porous IDPs and some unequilibrated ordinary chondrites [ 2], that is commonly observed in chondritic-porous IDPs. Recently, LIME olivine has been also found in comet Wild-2 (Stardust) samples [3], indicating that LIME olivine is a common mineral component of comets. LIME olivine has been proposed to form as a high temperature condensate in the protosolar nebula [2]. Brownleeite grains also likely formed as high-temperature condensates either in the early Solar System or in the outflow of an evolved star or supernova explosion [1]. The isotopic composition of the brownleeite grains may strongly constrain their ultimate source. To test this hypothesis, we performed isotopic analyses of the brownleeite and the associated LIME olivine, using the NASA/JSC NanoSIMS 50L ion microprobe.

  9. Calcium isotopes in wine

    Science.gov (United States)

    Holmden, C. E.

    2011-12-01

    The δ 44/40Ca values of bottled wine vary between -0.76% to -1.55% on the seawater scale and correlate weakly with inverse Ca concentration and Mg/Ca ratio, such that the lowest δ 44/40Ca values have the highest Ca concentrations and lowest Mg/Ca ratios. The correlation is notable in the sense that the measured wines include both whites and reds sampled from different wine growing regions of the world, and cover a wide range of quality. Trends among the data yield clues regarding the cause of the observed isotopic fractionation. White wines, and wines generally perceived to be of lower quality, have lower δ 44/40Ca values compared to red wines and wines of generally perceived higher quality. Quality was assessed qualitatively through sensory evaluation, price, and scores assigned by critics. The relationship between δ 44/40Ca and wine quality was most apparent when comparing wines of one varietal from one producer from the same growing region. In the vineyard, wine quality is related to factors such as the tonnage of the crop and the ripeness of the grapes at the time of harvesting, the thickness of the skins for reds, the age of the vines, as well as the place where the grapes were grown (terroir). Quality is also influenced by winemaking practices such as fermentation temperature, duration of skin contact, and barrel ageing. Accordingly, the relationship between δ 44/40Ca and wine quality may originate during grape ripening in the vineyard or during winemaking in the cellar. We tested the grape ripening hypothesis using Merlot grapes sampled from a vineyard in the Okanagan, British Columbia, using sugar content (degrees Brix) as an indicator of ripeness. The grapes were separated into pulp, skin, and pip fractions and were analyzed separately. Thus far, there is no clear evidence for a systematic change in δ 44/40Ca values associated with progressive ripening of grapes in the vineyard. On the day of harvesting, the δ 44/40Ca value of juice squeezed from

  10. New dates for the Fontéchevade (Charente, France) Homo remains.

    Science.gov (United States)

    Chase, Philip G; Debénath, André; Dibble, Harold L; McPherron, Shannon P; Schwarcz, Henry P; Stafford, Thomas W; Tournepiche, Jean-François

    2007-02-01

    Homo I from the site of Fontéchevade, France, has long been an anomaly in the European fossil record. The specimen is a fragment of human frontal bone that lacks a supraorbital torus and appears to belong to an anatomically modern Homo sapiens. However, the level from which it was recovered in 1947 was dated on the basis of associated faunal and lithic material to the last interglacial or earlier. As a result, Homo I has been interpreted, among other things, as a representative of a pre-sapiens lineage in Europe. This paper reports on recent ESR and radiocarbon dates that indicate that the specimen almost certainly dates to oxygen isotope stage 3, which brings it in line with other evidence for the entry of modern Homo sapiens into Europe.

  11. Laser technologies for ultrasensitive groundwater dating using long-lived isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Backus, Sterling [KMLabs Inc., Boulder, CO (United States)

    2017-01-31

    In this phase I work, we propose to construct and demonstrate a 103 nm laser based on resonantly enhanced and phase matched fifth harmonic generation in hollow waveguides driven by a high power, low cost and compact ultrafast fiber laser. (Figure 4) This VUV laser source can potentially produce >100 milliwatts of VUV light at 103 nm with pulse repetition-rates of 100 kHz to 100 MHz, ideal for the above-mentioned applications. This technology is state-of-the-art and potentially compact, fieldable, low-cost, and of broad interest for a variety of science and technology applications. Laser-based VUV sources in the past have exhibited low repetition rate, low efficiency, low beam quality, and are based on expensive laser sources. Our approch is to combine ultrafast fiber laser drive technology, ultrafast pulses, and our proven waveguide technology, to create a high repetition rate, high average power VUV source for producing high yield metastable Krypton. At KMLabs we have been offering EUV light sources employing the high harmonic generation (HHG) process driven by high-power femtosecond lasers for >5 years now. Recently, we have developed much smaller scale (briefcase size), but still high average power femtosecond fiber laser sources to supply other markets, and create new ones. By combining these new laser sources with our patented waveguide frequency upconversion technology, we expect to be able to obtain >20mW average power initially, with potentially much higher powers depending on wavelength, in an affordable VUV product. For comparison, our current EUV light sources based on ti:sapphire generate an average power of ~5 µW (albeit at shorter 29 nm wavelength), and we are aware of one other supplier that has developed a VUV (112 nm) light source with ~10-20 µW power.

  12. Application of 210Po isotope dating for chronological assessment of organochlorine pesticides in estuarine sediment

    Directory of Open Access Journals (Sweden)

    G.G. Pandit

    2014-04-01

    The total HCH concentration in the surface sediment samples was in the range of 5.6–13.3 ng/g while total DDT concentration in the surface sediment samples was in the range of 3.2–5.5 ng/g. DDT and γ-HCH were the dominant OCPs in sediments from the creek. The sedimentation rate was determined using 210Po activity measurement in different cores of the sediment and was found to be 0.67 cm/y on average. It was observed that the sediments were highly contaminated during the period of 1970–80 just after the green revolution in India. Total DDT was highest in the 1974–1978 layers of the sediments. Total HCH was highest in the 1972–1976 layers at all the locations.

  13. (AJST) EU/Th AND 14C ISOTOPE DATING OF LAKE SEDIMENTS ...

    African Journals Online (AJOL)

    opiyo

    sampling resolution has been coarse, entailing extrapolations over time periods where there may have been .... is the assumption that atmospheric 14C levels have remained constant ... reservoirs; variations in the amount of carbon dioxide in.

  14. Chromatographic separation of fructose from date syrup.

    Science.gov (United States)

    Al Eid, Salah M

    2006-01-01

    The objective of this study is to provide a process for separating fructose from a mixture of sugars containing essentially fructose and glucose, obtained from date palm fruits. The extraction procedure of date syrup from fresh dates gave a yield of 86.5% solids after vacuum drying. A process for separating fructose from an aqueous solution of date syrup involved adding the date syrup solutions (20, 30 and 40% by weight) to a chromatographic column filled with Dowex polystyrene strong cation exchange gel matrix resin Ca2 + and divinylbenzene, a functional group, sulfonic acid, particle size 320 microm, with a flow rate of 0.025 and 0.05 bed volume/min, under 30 and 70 degrees C column temperature. After the date sugar solution batch, a calculated quantity of water was added to the column. Glucose was retained by the resin more weakly than fructose and proceeded faster into the water batch flowing ahead. Three fractions were collected: a glucose-rich fraction, a return fraction, and a fructose-rich fraction. The return fraction is based on when the peaks of fructose and glucose were reached, which could be determined by means of an analyzer (polarimeter) based on the property of glucose and fructose solutions to turn the polarization level of polarized light. A high yield of fructose is obtained at 70 degrees C column temperature with a flow rate of 0.025 bed volume/min and date syrup solution containing 40% sugar concentration. The low recovery by weight obtained using date syrup solutions having a sugar concentration of 20 and 30%, encourages the use of a concentration of 40%. However, with the 40% date syrup supply the average concentrations of glucose and fructose in the return fractions were more than 40%, which can be used for diluting the thick date syrup solution extracted from dates.

  15. Groundwater surface water interaction study using natural isotopes tracer

    Science.gov (United States)

    Yoon, Yoon Yeol; Kim, Yong Chul; Cho, Soo Young; Lee, Kil Yong

    2015-04-01

    Tritium and stable isotopes are a component of the water molecule, they are the most conservative tracer for groundwater study. And also, radon is natural radioactive nuclide and well dissolved in groundwater. Therefore, these isotopes are used natural tracer for the study of surface water and groundwater interaction of water curtain greenhouse area. The study area used groundwater as a water curtain for warming tool of greenhouse during the winter, and is associated with issues of groundwater shortage while being subject to groundwater-river water interaction. During the winter time, these interactions were studied by using Rn-222, stable isotopes and H-3. These interaction was monitored in multi depth well and linear direction well of groundwater flow. And dam effect was also compared. Samples were collected monthly from October 2013 to April 2014. Radon and tritium were analyzed using Quantulus low background liquid scintillation counter and stable isotopes were analyzed using an IRIS (Isotope Ratio Infrared Spectroscopy ; L2120-i, Picarro). During the winter time, radon concentration was varied from 0.07 Bq/L to 8.9 Bq/L and different interaction was showed between dam. Surface water intrusion was severe at February and restored April when greenhouse warming was ended. The stable isotope results showed different trend with depth and ranged from -9.16 ‰ to -7.24 ‰ for δ 18O value, while the δD value was ranged from -57.86 ‰ to -50.98 ‰. The groundwater age as dated by H-3 was ranged 0.23 Bq/L - 0.59 Bq/L with an average value of 0.37 Bq/L.

  16. AMS radiocarbon dating of mortar: The case study of the medieval UNESCO site of Modena

    Energy Technology Data Exchange (ETDEWEB)

    Carmine, Lubritto [Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche & CIRCE lab, Seconda Università degli Studi di Napoli, I-81100 Caserta (Italy); Caroselli, Marta; Lugli, Stefano [Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, I-41100 Modena (Italy); Marzaioli, Fabio [Dipartimento di Matematica e Fisica & CIRCE lab, Seconda Università degli Studi di Napoli, I-81100 Caserta (Italy); Nonni, Sara [Università degli Studi “Sapienza”, Dipartimento di Scienze della Terra, I-00185 Roma (Italy); Marchetti Dori, S. [Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, I-41100 Modena (Italy); Terrasi, Filippo [Dipartimento di Matematica e Fisica & CIRCE lab, Seconda Università degli Studi di Napoli, I-81100 Caserta (Italy)

    2015-10-15

    The carbon dioxide contributing to binder formation during the set of a lime mortar reflects the atmospheric {sup 14}C content at the time of construction of a building. For this reason, the {sup 14}C dating of mortars is used with increasing frequencies in archaeological and architectural research. Mortars, however, may also contain carbonaceous contaminants potentially affecting radiocarbon dating. The Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) of the Second University of Naples (SUN) has recently obtained some promising results in mortar radiocarbon dating thanks to the development of a procedure (i.e. CryoSoniC/Cryo2SoniC) aiming to eliminate exogenous C contamination that may occur in a mortar. The construction history of the UNESCO World Heritage Site of Modena (Italy) is still controversial and represents a challenging case study for the application of absolute dating methodologies for different reasons. From the point of view of {sup 14}C dating, for example, given the high percentage of carbonate aggregates composing these samples, Modena mortars represent an experimental test particularly indicative of exogenous carbon sources suppression ensuring methodology accuracy. In this paper several AMS Radiocarbon dates were carried out on lime lumps with the aim to: (i) verify procedure accuracy by a comparison of the results obtainable from lime lumps dated after different treatments (i.e. bulk lime lumps vs. CryoSoniC purified lime lumps); (ii) compare different building phases absolute chronology for the medieval UNESCO site of Modena, with that assumed by historical sources in order to assess preliminary the {sup 14}C dating feasibility for of the site. Historical temporal constraints and mortar clustering, based on petrography, have been applied to define a temporal framework of the analyzed structure. Moreover, a detailed petrographic characterization of mortars was used both as a preliminary tool for the choice of samples

  17. 38 CFR 3.54 - Marriage dates.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Marriage dates. 3.54..., Compensation, and Dependency and Indemnity Compensation Relationship § 3.54 Marriage dates. A surviving spouse may qualify for pension, compensation, or dependency and indemnity compensation if the marriage to...

  18. 16 CFR 1209.11 - Effective date.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Effective date. 1209.11 Section 1209.11 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS INTERIM SAFETY STANDARD FOR CELLULOSE INSULATION The Standard § 1209.11 Effective date. All cellulose insulation...

  19. Accounting the Events after the Balance Date

    Directory of Open Access Journals (Sweden)

    Ilincuţă Lucian-Dorel

    2014-10-01

    Full Text Available The events after the balance date are those events, favorable and unfavorable, that occur between the balance date (the end of the reporting period and the date at which the annual financial statements are authorized for issue by the executive management of the entity (e.g. Board of Directors. We identify two types of events: events after the balance date, which lead to financial statements adjusting and events after the balance date, which do not lead to financial statements adjusting. The process of authorizing the publishing of the financial statements depends on the structure of the reporting entity, on normalization and on procedures followed in preparing and finalizing the financial statements. Some entities submit the financial statements for approval to their owners after they have been published. In such cases, the financial statements are authorized for publication on the date of publication, not the date they were approved by the owners. The events after the reporting period include all events up to the date the financial statements are authorized for publication, even if those events occur after the public announcement of profit or of other selected financial information.

  20. 7 CFR 987.13 - Free dates.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... RIVERSIDE COUNTY, CALIFORNIA Order Regulating Handling Definitions § 987.13 Free dates. Free dates means... to acquire them at prices reasonably comparable with prices received domestically) and which are...

  1. 40 CFR 63.403 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Compliance dates. 63.403 Section 63.403 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL... Hazardous Air Pollutants for Industrial Process Cooling Towers § 63.403 Compliance dates. The...

  2. 14 CFR 255.8 - Sunset Date.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Sunset Date. 255.8 Section 255.8 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS AIRLINE COMPUTER RESERVATIONS SYSTEMS § 255.8 Sunset Date. Unless extended by a document published...

  3. Date palm production and pest management challenges

    Science.gov (United States)

    Abstract: Date palm, Phoenix dactylifera, is a monocotyledonous species belong- ing to the palm family (Arecaceae or Palmae) which is perennial and dioecious and cultivated mostly in the arid regions of the world. Date palm is important to the agrarian economy of several countries, with the ability ...

  4. ‘Wiggle Matching’ Radiocarbon Dates

    NARCIS (Netherlands)

    Bronk Ramsey, C.; Plicht, J. van der; Weninger, B.; Boaretto, E.; Carmi, I.

    2001-01-01

    This paper covers three different methods of matching radiocarbon dates to the ‘wiggles’ of the calibration curve in those situations where the age difference between the 14C dates is known. These methods are most often applied to tree-ring sequences. The simplest approach is to use a classical Chi-

  5. Accelerator mass spectrometry dating at Catalhoeyuek

    Energy Technology Data Exchange (ETDEWEB)

    Goektuerk, E.H. [Dept. of Chemistry, Middle East Technical Univ., Ankara (Turkey); Hillegonds, D.J.; Lipschutz, M.E. [Dept. of Chemistry, Purdue Univ., West Lafayette, IN (United States); Hodder, I. [Dept. of Cultural and Social Anthropology, Standford Univ., Standford, CA (United States)

    2002-07-01

    Several charred plant and charcoal samples from various stratigraphic levels of the Neolithic Site, Catalhoeyuek - Turkey, were dated in the AMS facility of Purdue University (PRIME Lab). Radiocarbon dates reveal a complicated chronology, as was foreseen from archeological investigations. Our measurements suggest that this unique Neolithic town may have been initiated at the East mound around 8390 BP. (orig.)

  6. 40 CFR 62.12612 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... from Hospital/medical/infectious Waste Incinerators § 62.12612 Effective date. The effective date for the portion of the plan applicable to existing hospital/medical/infectious waste incinerators is... Than 250 Tons Per Day of Municipal Solid Waste...

  7. 40 CFR 62.10352 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Emissions from Existing Municipal Solid Waste Landfills § 62.10352 Effective date. The effective date of the plan for municipal solid waste landfills is August 2, 1999. Air Emissions From Hospital/Medical/Infectious Waste Incinerators Source: Sections 62.10360 through 62.10362 appear at 65 FR 38740, June 22,...

  8. 40 CFR 62.5152 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Existing Municipal Solid Waste Landfills (section 111(d) Plan) § 62.5152 Effective date. The effective date of the plan for municipal solid waste landfills is November 8, 1999. Emissions From Existing Hospital/Medical/Infectious Waste Incinerators (HMIWIs)(Section 111(d)/129 Plan) Source: Sections 62.5160...

  9. 40 CFR 62.3632 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Existing Municipal Solid Waste Landfills § 62.3632 Effective date. The effective date of the plan for municipal solid waste landfills is May 30, 2000. Metals, Acid Gases, Organic Compounds and Nitrogen Oxide Emissions From Existing Hospital/Medical Infectious Waste Incinerators Source: Sections 62.3640 through...

  10. 40 CFR 62.10362 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Emissions from Hospital/medical/infectious Waste Incinerators § 62.10362 Effective date. The effective date for the portion of the plan applicable to existing hospital/medical/infectious waste incinerators is... Than 250 Tons Per Day of Municipal Solid Waste...

  11. 40 CFR 62.11112 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Emissions from Existing Municipal Solid Waste Landfills § 62.11112 Effective date. The effective date of the plan for municipal solid waste landfills is March 16, 1998. Air Emissions From Hospital/Medical/Infectious Waste Incinerators Source: Sections 62.11120 through 62.11122 appear at 65 FR 38740, June 22,...

  12. 40 CFR 62.12602 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Emissions from Existing Municipal Solid Waste Landfills § 62.12602 Effective date. The effective date of the plan for municipal solid waste landfills is July 31, 1998. Air Emissions From Hospital/Medical/Infectious Waste Incinerators Source: Sections 62.12610 through 62.12612 appear at 65 FR 38740, June 22,...

  13. 40 CFR 62.12127 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... Gas Emissions from Existing Municipal Solid Waste Landfills (section 111(d) Plan) § 62.12127 Effective date. The effective date of the plan for municipal solid waste landfills is July 23, 2001. Emissions From Existing Hospital/Medical/Infectious Waste Incinerators (HMIWIs) (Section 111(d)/129 Plan)...

  14. 44 CFR 206.17 - Effective date.

    Science.gov (United States)

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Effective date. 206.17 Section 206.17 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY DISASTER ASSISTANCE FEDERAL DISASTER ASSISTANCE General § 206.17 Effective date....

  15. 31 CFR 357.1 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Effective date. 357.1 Section 357.1 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE... AND BILLS HELD IN LEGACY TREASURY DIRECT General Information § 357.1 Effective date. Subpart B of...

  16. 40 CFR 63.1501 - Dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Dates. 63.1501 Section 63.1501 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL... Hazardous Air Pollutants for Secondary Aluminum Production General § 63.1501 Dates. (a) The owner...

  17. 32 CFR 242a.8 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 2 2010-07-01 2010-07-01 false Effective date. 242a.8 Section 242a.8 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS... § 242a.8 Effective date. This part shall become effective on March 12, 1977....

  18. 11 CFR 9006.2 - Filing dates.

    Science.gov (United States)

    2010-01-01

    ... 11 Federal Elections 1 2010-01-01 2010-01-01 false Filing dates. 9006.2 Section 9006.2 Federal Elections FEDERAL ELECTION COMMISSION PRESIDENTIAL ELECTION CAMPAIGN FUND: GENERAL ELECTION FINANCING REPORTS AND RECORDKEEPING § 9006.2 Filing dates. The reports required to be filed under 11 CFR...

  19. 7 CFR 1730.65 - Effective dates.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 11 2010-01-01 2010-01-01 false Effective dates. 1730.65 Section 1730.65 Agriculture Regulations of the Department of Agriculture (Continued) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE... dates. (a) All electric program borrowers with an approved electric program loan as of July 8,...

  20. 31 CFR 10.93 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Effective date. 10.93 Section 10.93 Money and Finance: Treasury Office of the Secretary of the Treasury PRACTICE BEFORE THE INTERNAL REVENUE SERVICE General Provisions § 10.93 Effective date. Except as otherwise provided in each section...

  1. 32 CFR 270.3 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 2 2010-07-01 2010-07-01 false Effective date. 270.3 Section 270.3 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS... Effective date. This part is effective on May 15, 1997....

  2. 49 CFR 325.3 - Effective date.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Effective date. 325.3 Section 325.3 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION... STANDARDS General Provisions § 325.3 Effective date. The rules in this part are effective on October...

  3. 32 CFR 191.10 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 2 2010-07-01 2010-07-01 false Effective date. 191.10 Section 191.10 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS THE DOD CIVILIAN EQUAL EMPLOYMENT OPPORTUNITY (EEO) PROGRAM § 191.10 Effective date. This part...

  4. 7 CFR 1485.24 - Applicability date.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Applicability date. 1485.24 Section 1485.24 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT... FOREIGN MARKETS FOR AGRICULTURAL COMMODITIES Market Access Program § 1485.24 Applicability date....

  5. 31 CFR 226.7 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Effective date. 226.7 Section 226.7 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE... LOAN DEPOSITARIES § 226.7 Effective date. The provisions of this part become effective November 2, 1978....

  6. 40 CFR 63.1545 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Compliance dates. 63.1545 Section 63.1545 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... for Hazardous Air Pollutants for Primary Lead Smelting § 63.1545 Compliance dates. (a) Each owner...

  7. Strategies for Family Facilitation of Play Dates

    Science.gov (United States)

    Chambers, Cynthia R.; Horn, Eva M.

    2010-01-01

    Play dates can serve several functions for young children, including children with social difficulties, such as developmental delays, behavioral disorders, autism spectrum disorders, and shyness. Play dates provide children with additional opportunities to be around peers and to practice skills associated with peer play interactions. Play dates…

  8. 18 CFR 808.19 - Effective date.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Effective date. 808.19 Section 808.19 Conservation of Power and Water Resources SUSQUEHANNA RIVER BASIN COMMISSION HEARINGS AND ENFORCEMENT ACTIONS Compliance and Enforcement § 808.19 Effective date. This part shall be effective...

  9. 18 CFR 807.4 - Effective date.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Effective date. 807.4 Section 807.4 Conservation of Power and Water Resources SUSQUEHANNA RIVER BASIN COMMISSION WATER WITHDRAWAL REGISTRATION § 807.4 Effective date. This part shall be effective on January 1, 2007....

  10. Jealousy during Dating among Female College Students

    Science.gov (United States)

    Khanchandani, Laveena; Durham, Thomas W.

    2009-01-01

    This study examined the relationship between several situational and personality variables and jealousy in dating relationships among 100 college women volunteers who completed a series of questionnaires about themselves and their dating situations. Six research questions were examined. Results showed that jealousy was lower for women in a steady…

  11. Peer Involvement in Adolescent Dating Violence

    Science.gov (United States)

    Stephenson, Pam S.; Martsolf, Donna; Draucker, Claire Burke

    2013-01-01

    This study investigated the ways in which peers are involved in adolescent dating violence. Eighty-eight young adults aged 18-21 were interviewed and asked to reflect on aggressive dating relationships they experienced as teens. The researchers used grounded theory to analyze the data. Findings showed that male and female peers were involved in…

  12. Teen Dating Violence Prevention Program Assessment

    Science.gov (United States)

    Lucas, Quincy Arrianna Rose

    2013-01-01

    The American Psychological Association (APA) has identified the prevention of and intervention in relationship violence as a top priority (APA, n.d.). According to the Center for Disease Control and Prevention's 2012 Teen Dating Violence Fact Sheet, dating violence is a serious problem in the United States. In accordance with Foshee et al. (1998):…

  13. Dating violence and suicidal behavior in adolescents.

    Science.gov (United States)

    Holmes, Kristin; Sher, Leo

    2013-01-01

    The aim of this paper is to assess the possible consequences of adolescent physical, emotional and sexual dating violence through a review of the literature on the topic. An electronic search of major biomedical bibliographic databases (Pubmed, ISI, PsycINFO) was used to retrieve articles providing information on the prevalence rates, risk factors, associated consequences and possible preventive measures for adolescent dating violence across different populations. Currently, there have been few longitudinal studies conducted to identify potential risk factors for entering a violent dating relationship in adolescence. Risky behaviors such as early sexual intercourse may predispose someone for victimization. Dating violence itself is also a predictor of future dating violence. Adolescent dating violence was associated with an increase in other violence-related behaviors, substance use, depression, poorer educational outcomes, posttraumatic stress, unhealthy weight control and risky sexual behavior. The association between adolescent dating violence and an increase in suicidal behavior is a major public health concern. Future research should focus on longitudinal studies so that a causal relationship between dating violence and suicidality may be better understood.

  14. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20141655 Gao Linzhi(Institute of Geology,CAGS,Beijing 100037,China);Ding Xiaozhong The Revision of the Chentangwu Formation in Neoproterozoic Stratigraphic Column:Constraints on Zircon U-Pb Dating of Tuff from the Mengshan Section in Pujiang County,Zhejiang Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.988-995,5 illus.,1 plate,2 tables,24 refs.)

  15. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>20080453 Gu Zhaoyan(Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029);Guo Zhengtang 10 Be Concentration Relation to Chemical Compositions of Chinese Loess and Red Clay as a Potential Dating Method(Quaternary Sciences,ISSN1001-7410,CN11-2708/P,26(2),2006,p.244-249,3 illus.,1 table,21 refs.)

  16. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正>20041584 Cheng Hai (Department of Geology & Geophysics, University of Minnesota, Minneapolis, United States); Lawrence, R. U/Th and U/Pa Dating of Nanjing Man, Jiangsu Province (Geological Journal of China Universities, ISSN 1006 - 7493, CN 32 -1440/P, 9(4), 2003, p. 667-677, 2 illus. , 2 tables, 28 refs. , with English abstract) Key words: Homo erectus, Nanjing, Jiangsu Province

  17. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>20082540 Ding Ping(Guangzhou Institute of Geochemistry,Chinese Academy of Sciences, Guangzhou 510640,China);Shen Chengde 14C Chronological Research of Ancient Forest Cosystem in Sihui,Guangdong Province (Quaternary Sciences,ISSN 1001—7410,CN 11—2708/P,27(4),2007,p.492—498,7 illus.,3 tables,23 refs.) Key words:radiocarbon dating,Guang- dong Province

  18. U-Series dates for stalagmitic flowstone E (Riss/Würm interglaciation) at Grotte du Lazaret, Nice, France

    Science.gov (United States)

    Falgueres, Christophe; de Lumley, Henry; Bischoff, James L.

    1992-01-01

    Several samples of stalagmitic flowstone (Ensemble E) at Grotte du Lazaret (Nice, France) were dated by U-series isotopes. The results show that this speleothem began to grow about 130,000 yr B.P. and continued to about 70,000 yr B.P., coinciding almost exactly with the last interglaciation (isotope stage 5). Even though Ensemble E is not in direct stratigraphic relation with the cave deposits, this study shows that the Acheulian artifacts industry and fauna within Lazaret are older than the Riss/Wurm interglaciation.

  19. Silicon isotope study of thermal springs in Jiaodong Region,Shandong Province

    Institute of Scientific and Technical Information of China (English)

    徐跃通; 李红梅; 冯海霞; 周晨; 吴元芳; 张邦花

    2001-01-01

    Based on δ30Si and δ32Si isotope geochemistry, the origin and evolutionary mechanism of thermal springs in Jiaodong region are studied. The mean value of δ30Si of dissolved silica of thermal spring water in Jiaodong is 0.1‰. Thermal spring water ages using δ32Si dating method range from 387a to 965a.

  20. Carbon and Oxygen Isotope Dendrochronology in Sub-Fossil Bog Oak Tree Rings - A Preliminary Study

    NARCIS (Netherlands)

    Sass, U.G.W.; Poole, I.; Wils, T.; Helle, G.; Schleser, G.H.; Bergen, van P.

    2005-01-01

    Isotope dendroclimatology is a relatively new field investigating environmental factors that control the radial growth of trees. Tree-ring series of sub-fossil bog oaks can be dated from sites across northwest Europe indicating that the environmental change(s) were regional rather than local. Bog

  1. Carbon and Oxygen Isotope Dendrochronology in Sub-Fossil Bog Oak Tree Rings - A Preliminary Study

    NARCIS (Netherlands)

    Sass, U.G.W.; Poole, I.; Wils, T.; Helle, G.; Schleser, G.H.; Bergen, van P.

    2005-01-01

    Isotope dendroclimatology is a relatively new field investigating environmental factors that control the radial growth of trees. Tree-ring series of sub-fossil bog oaks can be dated from sites across northwest Europe indicating that the environmental change(s) were regional rather than local. Bog oa

  2. Competition from Isotopic Modelling

    Directory of Open Access Journals (Sweden)

    Virginie Fabre

    2011-01-01

    Full Text Available During later MOIS3, in Europe two populations were present, autochthonous Neanderthals and modern humans. Ecological competition between these two populations has often been evoked but never demonstrated. Our aim is to establish whether resource competition occurred. In this paper, in order to examine the possibility of ecological competition between these two populations, 599 isotopic data were subjected to rigorous statistical treatment and analysis through mixing models. The aim of this paper was to compare dietary strategies of Neanderthals and modern humans over time. Our conclusions suggest that Neanderthals and modern humans shared dietary habits in the particular environmental context of MOIS3 characterised in Europe by climatic deterioration. In this environmental context, the resource competition between Neanderthals and modern humans may have accelerated the disappearance of the Neanderthal population.

  3. Isotope Effects in ESR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Werner Herrmann

    2013-06-01

    Full Text Available In order to present the relationship between ESR spectroscopy and isotope effects three levels are considered: (i ESR spectroscopy is described on a general level up to the models for interpretation of the experimental spectra, which go beyond the usually used time and mass independent spin-Hamilton operator, (ii the main characteristics of the generalized isotope effects are worked out, and finally (iii the basic, mainly quantum mechanical effects are used to describe the coupling of electron spins with the degrees of freedom, which are accessible under the selected conditions, of the respective paramagnetic object under investigation. The ESR parameters and the respective models are formalized so far, that they include the time and mass depending influences and reflect the specific isotope effects. Relations will be established between the effects in ESR spectra to spin relaxation, to spin exchange, to the magnetic isotope effect, to the Jahn-Teller effects, as well as to the influence of zero-point vibrations. Examples will be presented which demonstrate the influence of isotopes as well as the kind of accessible information. It will be differentiated with respect to isotope effects in paramagnetic centres itself and in the respective matrices up to the technique of ESR imaging. It is shown that the use of isotope effects is indispensable in ESR spectroscopy.

  4. The Sima de los Huesos hominids date to beyond U/Th equilibrium (>350 kyr) and perhaps to 400-500 kyr: New radiometric dates

    Science.gov (United States)

    Bischoff, J.L.; Shamp, D.D.; Aramburu, Arantza; Arsuaga, J.L.; Carbonell, E.; Bermudez de Castro, Jose Maria

    2003-01-01

    The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mud breccia underlying an accumulation of the Middle Pleistocene cave bear (U. deningeri). Earlier dating estimates of 200 to 320 kyr were based on U-series and ESR methods applied to bones, made inaccurate by unquantifiable uranium cycling. We report here on a new discovery within the Sima de los Huesos of human bones stratigraphically underlying an in situ speleothem. U-series analyses of the speleothem shows the lower part to be at isotopic U/Th equilibrium, translating to a firm lower limit of 350 kyr for the SH hominids. Finite dates on the upper part suggest a speleothem growth rate of c. 1 cm/32 kyr. This rate, along with paleontological constraints, place the likely age of the hominids in the interval of 400 to 600 kyr. ?? 2002 Elsevier Science Ltd. All rights reserved.

  5. Strontium isotope analysis of archaeological fauna at the Erlitou site

    Institute of Scientific and Technical Information of China (English)

    ZHAO ChunYan; YANG Jie; YUAN Jing; LI ZhiPeng; XU Hong; ZHAO HaiTao; CHEN GuoLiang

    2012-01-01

    The Erlitou site is located at Yanshi City,Henan Province.This site is a large settlement site of Erlitou culture,and it is dated to 3800-3500 a BP.Five kinds of domestic animals,i.e.,dogs,pigs,sheep,goats,and cattle were found from the site.In this paper,two problems have emerged in studies involving the estimation of local isotope levels and the distinction of migrants from locals.Tooth enamel samples fron 17 domestic animals individuals were analyzed for strontium isotope ratio (87Sr/86Sr),by the thermal ionization mass spectrometry,including 10 pigs,5 sheep and 2 cattle.The results show that the mean 87Sr/86Sr ratios of 10 pigs enamel samples were 0.712078,Based on the local strontium isotopes ratio range determined by the mean 87Sr/86Sr ratios ±2σrof 10 pig enamel samples (0.712256-.711900),we found that five sheep and one cattle from the Erlitou site fell well outside the local strontium isotopes ratio range and were considered to be non-local.

  6. Dating low-temperature alteration of the upper oceanic crust

    Science.gov (United States)

    Coogan, L. A.; Hinton, R. W.; Gillis, K. M.; Dosso, S. E.

    2011-12-01

    Off-axis hydrothermal systems lead to extensive chemical exchange between the oceans and upper oceanic crust but it is unclear when this exchange occurs. We address this using a new dating approach and via the re-evaluation of existing data that contain age information. We have developed a method to directly date adularia, a common alkali-rich phase in old oceanic crust, using the 40K to 40Ca radiogenic decay system. In situ analysis, using the Cameca 1270 ion microprobe at the University of Edinburgh, allows small, replacive, secondary mineral grains to be analyzed. In comparison to previous radiogenic dating of low-temperature secondary minerals, using Rb-Sr and K-Ar approaches on mineral separates, this approach has the advantages that: (i) analysis is not limited to large, void filling, grains; (ii) the initial isotopic ratio is well constrained; (iii) contamination and phase heterogeneity are minimized; and (iv) the daughter isotope is relatively immobile. However, the requirement to analyse doubly charged ions, to reduce molecular interferences and suppress the presence of 40K on 40Ca, leads to low count rates [1]; e.g. single spot ages have uncertainties of 10's of millions of years. Combining all analyses for a given sample gives best fitting instantaneous precipitation "ages" of 102 and 70 Myr for DSDP Holes 417A and 543A (versus crustal ages of 120 and 80 Myr). The scatter in the data are consistent with adularia precipitation over >30 Myr. The timing of carbonate precipitation in the upper oceanic crust can be constrained from comparison of their 87Sr/86Sr to the seawater Sr-isotope curve if the proportion of basaltic Sr in the fluid can be constrained. Modeling such data from 12 drill cores shows that they are best fit by a model in which >90% of carbonate precipitation occurs over ≤20 Myr after crustal formation [2]. Evaluation of published Rb-Sr "isochron" data [3,4] shows that these data can be explained in different ways. The "isochron

  7. Isotope-edited infrared spectroscopy.

    Science.gov (United States)

    Buchner, Ginka S; Kubelka, Jan

    2012-01-01

    Isotope-edited infrared (IR) spectroscopy is a powerful tool for studying structural and dynamical properties of peptides and proteins with site-specific resolution. Labeling of selected amide carbonyls with (13)C results in detectable sidebands of amide I' vibrations, which provide information about local conformation and/or solvent exposure without structural perturbation to the protein. Incorporation of isotopically labeled amino acids at specific positions is achieved by the chemical synthesis of the studied proteins. We describe the basic procedures for synthesis of (13)C isotopically edited protein samples, experimental IR spectroscopic measurements, and analysis of the site-specific structural changes from the thermal unfolding IR data.

  8. Compelling Research Opportunities using Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-04-23

    Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1

  9. Carbon isotope geochemistry and geobiology

    Science.gov (United States)

    Desmarais, D.

    1985-01-01

    Carbon isotope fractionation values were used to understand the history of the biosphere. For example, plankton analyses confirmed that marine extinctions at the end of the Cretaceous period were indeed severe (see Hsu's article in Sundquist and Broeker, 1984). Variations in the isotopic compositions of carbonates and evaporitic sulfates during the Paleozoic reflect the relative abundances of euxinic (anoxic) marine environments and organic deposits from terrestrial flora. The carbon isotopic composition of Precambrian sediments suggest that the enzyme ribulose bisphosphate carboxylase has existed for perhaps 3.5 billion years.

  10. Longitudinal relationships between individual and class norms supporting dating violence and perpetration of dating violence.

    Science.gov (United States)

    Taylor, Katherine A; Sullivan, Terri N; Farrell, Albert D

    2015-03-01

    Dating violence is commonly perpetrated in adolescence, making it imperative to understand risk factors in order to inform prevention efforts. Although individual norms supporting dating violence are strongly related to its perpetration, few studies have examined their longitudinal impact. Moreover, the influence of class norms (i.e., norms for students in the same grade, cohort, and school) supporting dating violence on perpetration has rarely been studied. The current study examined longitudinal relationships between individual and class norms supporting dating violence and perpetration of physical and psychological dating violence. Participants were two cohorts of sixth graders from 37 schools who were in dating relationships at Wave 1 and 6 months later at Wave 2 (N = 2,022; 43% female; 52% African American, 21% Latino/a, 20% White, and 7% other). The analyses used a multilevel approach, with students represented at Level 1 and classes (n = 74) at Level 2. The models tested direct effects of Wave 1 individual and class norms supporting dating violence on subsequent changes in perpetration of dating violence at Wave 2 and the extent to which gender moderated these relationships. The findings indicated that greater individual norms supporting male dating violence predicted greater change in perpetration of physical and psychological dating violence and greater individual norms supporting female dating violence predicted greater change in perpetration of psychological dating violence. Greater class norms supporting male dating violence predicted greater change in perpetration of physical dating violence; whereas greater class norms supporting female dating violence predicted less change in perpetration of physical dating violence. These findings highlight the need to address norms in early adolescence.

  11. Apparatus and process for separating hydrogen isotopes

    Science.gov (United States)

    Heung, Leung K; Sessions, Henry T; Xiao, Xin

    2013-06-25

    The apparatus and process for separating hydrogen isotopes is provided using dual columns, each column having an opposite hydrogen isotopic effect such that when a hydrogen isotope mixture feedstock is cycled between the two respective columns, two different hydrogen isotopes are separated from the feedstock.

  12. Parsing and Matching Dates in VIAF

    Directory of Open Access Journals (Sweden)

    Jenny A. Toves

    2014-10-01

    Full Text Available The Virtual International Authority File (OCLC Online Computer Library Center 2013 http://viaf.org is built from dozens of authority files with tens of millions of names in more than 150 million authority and bibliographic records expressed in multiple languages, scripts and formats. One of the main tasks in VIAF is to bring together personal names which may have various dates associated with them, such as birth, death or when they were active. These dates can be quite complicated with ranges, approximations, BCE dates, different scripts, and even different calendars. Analysis of the nearly 400,000 unique date strings in VIAF led us to a parsing technique that relies on only a few basic patterns for them. Our goal is to correctly interpret at least 99% of all the dates we find in each of VIAF’s authority files and to use the dates to facilitate matches between authority records. Python source code for the process described here is available at https://github.com/OCLC-Developer-Network/viaf-dates.

  13. Quantification of in Situ Biodegradation Rate Constants Using a Novel Combined Isotope Approach

    Science.gov (United States)

    Blum, P.; Sültenfuß, J.; Martus, P.

    2014-12-01

    Numerous studies have shown the enormous potential of the compound-specific isotope analysis (CSIA) for studying the biodegradation of organic compounds such as monoaromatic hydrocarbons (BTEX), polyaromatic hydrocarbons (PAH), chlorinated solvents and other organic contaminants and environmental transformation mechanisms in groundwater. In addition, two-dimensional isotope analysis such as carbon and hydrogen have been successfully studied indicating the potential to also investigate site-specific reaction mechanisms. The main objective of the current study however is to quantify real effective in situ biodegradation rate constants in a coal-tar contaminated aquifer by combining compound-specific isotope analysis (CSIA) and tracer-based (3H-3He) ground-water dating (TGD). Hence, groundwater samples are used to determine groundwater residence times, and carbon and hydrogen stable isotopes are analyzed for selected BTEX and PAH. The results of the hydrogen stable isotopes surprisingly indicate no isotope fractionation and therefore no biodegradation. In contrast, for stable carbon isotopes of selected BTEX such as o-xylene and toluene, isotope shifts are detected indicating active biodegradation under sulfate-reducing conditions. These and previous results of stable carbon isotopes show that only for o-xylene a clear evidence for biodegradation is possible for the studied site. Nevertheless, in combining these results with the groundwater residence times, which range between 1 year for the shallow wells (20 m below surface) and 41 years for the deeper wells (40 m below surface), it is feasible to effectively determine in situ biodegradation rate constants for o-xylene. Conversely, the outcome also evidently demonstrate the major limitations of the novel combined isotope approach for a successful implementation of monitored natural attenuation (MNA) at such field sites.

  14. A Phenomenological Investigation of Adolescent Dating Relationships and Dating Violence Counseling Interventions

    Science.gov (United States)

    Hays, Danica G.; Michel, Rebecca E.; Cole, Rebekah F.; Emelianchik, Kelly; Forman, Julia; Lorelle, Sonya; McBride, Rebecca; Sikes, April

    2011-01-01

    Despite the prevalence of dating violence, incidences often go unreported due to a lack of awareness among students as to appropriate dating behaviors. This phenomenology investigated how adolescents conceptualize and experience dating relationships. We explored adolescent females' definitions of healthy and abusive relationships, experiences with…

  15. TL and EPR dating: some applications

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, S. [Institute of Physics, University of Sao Paulo, Sao Paulo (Brazil)

    2006-07-01

    The intensity of thermoluminescence light emitted by a crystal is a function of radiation dose. The number of defects or of radicals in a crystal or organic substances is also a function of radiation dose. Since such defects or radicals present EPR signals, the EPR intensity is also a function of radiation dose. These facts are basis for radiation dosimetry and can be applied in dating of archaeological potteries or other materials, as well as in dating geological substances such as sediments, caves speleothemes, animal teeth and bones. Recent investigation on sensitized quartz based dosimeters and dating calcite covering ancient wall painting to find early settlers in Brazil will be presented. (Author)

  16. Approach to the human diet of the punic population of Can Marines (Ibiza. C an N stable isotope analysis on bone collagen

    Directory of Open Access Journals (Sweden)

    Domingo Carlos Salazar García

    2012-09-01

    Full Text Available We report here on the results of carbon and nitrogen stable isotope analysis on bone collagen of humans from the Punic site of Can Marines (V-IVth BC from the island of Ibiza (Spain. To date, there are few isotopic studies for this period from the Mediterranean. This article reports new isotopic data from a Western Mediterranean Punic rural settlement. The results show a terrestrial based diet with no isotopic evidence of marine or freshwater protein input, and suggest the presence of C4 resources in it.

  17. Osmium isotope and highly siderophile element constraints on ages and nature of meteoritic components in ancient lunar impact rocks

    Science.gov (United States)

    Fischer-Gödde, Mario; Becker, Harry

    2012-01-01

    The concentrations of highly siderophile elements (HSE: Re, Os, Ir, Ru, Pt, Rh, Pd, Au) and 187Os/188Os isotope compositions have been determined for 67 subsamples of six lunar impact rocks from the Apollo 14, 16 and 17 landing sites, and the lunar meteorite Dar al Gani (DaG) 400 using inductively coupled plasma mass spectrometry (ICP-MS) and negative thermal ionization mass spectrometry (N-TIMS). We report the first Re-Os isochron age on a lunar impact melt rock. 187Re-187Os isotope systematics for Apollo 16 sample 67935 define an isochron age of 4.21 ± 0.13 Ga (MSWD = 1.5), which is interpreted to reflect localized partitioning processes between solid metal-liquid metal as this rock melted. The new age adds further constraints on the significance of pre-4.0 Ga basin forming impacts on the Moon and possible mixing of ancient impactor compositions in lunar impact rocks. Linear correlations displayed by subsamples of a given impact rock in plots of HSE versus Ir concentrations are explained by dilution processes through essentially HSE-free anorthositic lunar crustal target rocks or binary mixing between a high HSE meteoritic end-member and a low HSE end-member composition. Slope-derived HSE ratios and 187Os/188Os of the meteoritic component in granulitic impactites 67915, 67955 and 79215 are similar to slightly volatile element depleted carbonaceous chondrites. Suprachondritic ratios of Ru/Ir, Pt/Ir, Rh/Ir, and Pd/Ir for Apollo 14 impact melt rock 14310 are similar to ratios observed for other Apollo 14 samples and Apollo 17 poikilitic impact melt rocks. Apollo 16 poikilitic and subophitic impact melt rocks 60315 and 67935 show slightly subchondritic Os/Ir and suprachondritic ratios of 187Os/188Os, Ru/Ir, Pt/Ir, Rh/Ir, Pd/Ir and Au/Ir. Their strongly fractionated HSE compositions are similar to some members of the IVA iron meteorite group and provide further evidence for an iron meteorite impactor component in Apollo 16 impact melt rocks. The range of chondritic

  18. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20150416Cao Dadi(State Key Laboratory of Marine Geology,Tongji University,Shanghai200092,China);Cheng Hao Recent Advances in Garnet Lu-Hf Geochronology(Geochimica,ISSN0379-1726,CN44-1398/P,43(2),2014,p.180-195,9illus.,92refs.)Key words:Lu-Hf dating,garnet group Garnets with high Lu/Hf ratios can be used to construct high precise isochrones.The garnet Lu-Hf geochronology has been extensively applied in various types of rocks,especially in metamorphic rocks from the orogens.

  19. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111126Ji Honglei(Institute of Hydrogeol-ogy and Environmental Geology,CAGS,Shi-jiazhuang050061,China);Zhao Hua Pre-liminary Study of Re-OSL on Water-De-posited Sediments(Seismology and Geology,ISSN0253-4967,CN11-2192/P,32(2),2010,p.320-326,4illus.,1table,10refs.)Key words:stream sediments,opticalstimulated luminescence dating,HebeiProvinceAccording to measuring the natural TT-OSL signals of the fine-grained quartzfrom both fluvial and lacustrine sediments,the dose recovery experiment and the comparison of the multiple aliquots

  20. Oxygen isotope constraints on the alteration temperatures of CM chondrites

    Science.gov (United States)

    Verdier-Paoletti, Maximilien J.; Marrocchi, Yves; Avice, Guillaume; Roskosz, Mathieu; Gurenko, Andrey; Gounelle, Matthieu

    2017-01-01

    We report a systematic oxygen isotopic survey of Ca-carbonates in nine different CM chondrites characterized by different degrees of alteration, from the least altered known to date (Paris, 2.7-2.8) to the most altered (ALH 88045, CM1). Our data define a continuous trend that crosses the Terrestrial Fractionation Line (TFL), with a general relationship that is indistinguishable within errors from the trend defined by both matrix phyllosilicates and bulk O-isotopic compositions of CM chondrites. This bulk-matrix-carbonate (BMC) trend does not correspond to a mass-dependent fractionation (i.e., slope 0.52) as it would be expected during fluid circulation along a temperature gradient. It is instead a direct proxy of the degree of O-isotopic equilibration between 17,18O-rich fluids and 16O-rich anhydrous minerals. Our O-isotopic survey revealed that, for a given CM, no carbonate is in O-isotopic equilibrium with its respective surrounding matrix. This precludes direct calculation of the temperature of carbonate precipitation. However, the O-isotopic compositions of alteration water in different CMs (inferred from isotopic mass-balance calculation and direct measurements) define another trend (CMW for CM Water), parallel to BMC but with a different intercept. The distance between the BMC and CMW trends is directly related to the temperature of CM alteration and corresponds to average carbonates and serpentine formation temperatures of 110 °C and 75 °C, respectively. However, carbonate O-isotopic variations around the BMC trend indicate that they formed at various temperatures ranging between 50 and 300 °C, with 50% of the carbonates studied here showing precipitation temperature higher than 100 °C. The average Δ17O and the average carbonate precipitation temperature per chondrite are correlated, revealing that all CMs underwent similar maximum temperature peaks, but that altered CMs experienced protracted carbonate precipitation event(s) at lower temperatures than