Origin and evolution of the Steamboat Springs siliceous sinter deposit, Nevada, U.S.A.     

Bridget Y. Lynne  Kathleen A. Campbell  Joseph Moore  P.R.L. Browne   《Sedimentary Geology》2008,210(3-4):111-131

Siliceous hot spring deposits from Steamboat Springs, Nevada, U.S.A., record a complex interplay of multiple, changing, primary environmental conditions, fluid overprinting and diagenesis. Consequently these deposits reflect dynamic geologic and geothermal processes. Two surface sinters were examined—the high terrace, and the distal apron-slope, as well as 13.11 m (43 ft) of core material from drill hole SNLG 87-29. The high terrace sinter consists of vitreous and massive-mottled silica horizons, while the distal deposit and core comprise dominantly porous, indurated fragmental sinters. Collectively, the three sinter deposits archive a complete sequence of silica phase diagenetic minerals from opal-A to quartz. X-ray powder diffraction analyses and infrared spectroscopy of the sinters indicate that the distal apron-slope consists of opal-A and opal-A/CT mineralogy; the core yielded opal-A/CT and opal-CT with minor opal-A; and the high terrace constitutes opal-C, moganite, and quartz. Mineralogical maturation of the deposit produced alternating nano–micro–nano-sized silica particle changes. Based on filament diameters of microbial fossils preserved within the sinter, discharging thermal outflows fluctuated between low-temperatures (< 35 °C, coarse filaments) and mid-temperatures ( 35–60 °C, fine filaments). Despite transformation to quartz, primary coarse and fine filaments were preserved in the high terrace sinter. AMS ¹⁴C dating of pollen from three horizons within core SNLG 87-29, from depths of 8.13 to 8.21 m (26′8″ to 26′11″), 10.13 to 10.21 m (33′3″ to 33′6″), and 14.81 to 14.88 m (48′7″ to 48′10″), yielded dates of 8684 ± 64 years, 11,493 ± 70 years and 6283 ±60 years, respectively. In the upper section of the core, the stratigraphically out-of-sequence age likely reflects physical mixing of younger sinter with quartzose sinter fragments derived from the high terrace. Within single horizons, mineralogical and morphological components of the sinter matrix were spatially patchy. Overall, the deposit was modified by sub-surface flow of alkali-chloride thermal fluids depositing a second generation of silica, and periodically, by acidic steam condensate formed during periods when the water table was low. Local faulting produced considerable fracturing of the sinter. Hence, the Steamboat Springs sinter experienced a complex history of primary and secondary hydrothermal, geologic and diagenetic events, and their inter-relationships and effects are locked within the physical, chemical and biological signatures of the deposit.  相似文献   

Viability theory for an ecosystem approach to fisheries   总被引：1，自引：1，他引：1  

Cury  Philippe M.; Mullon  Christian; Garcia  Serge M.; Shannon  Lynne J. 《ICES Journal of Marine Science》2005,62(3):577-584

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Atlas of Japan (East) Sea hydrographic properties in summer, 1999     

Lynne D. Talley  Pavel Tishchenko  Vladimir Luchin  Alexander Nedashkovskiy  Sergey Sagalaev  Dong-Jin Kang  Mark Warner  Dong-Ha Min 《Progress in Oceanography》2004,61(2-4):277

Hydrographic properties from CTD and discrete bottle sample profiles covering the Japan (East) Sea in summer, 1999, are presented in vertical sections, maps at standard depths, maps on isopycnal surfaces, and as property–property distributions. This data set covers most of the Sea with the exception of the western boundary region and northern Tatar Strait, and includes nutrients, pH, alkalinity, and chlorofluorocarbons, as well as the usual temperature, salinity, and oxygen observations.  相似文献   

Comparing the Benguela and Humboldt marine upwelling ecosystems with indicators derived from inter-calibrated models   总被引：10，自引：0，他引：10  

Moloney  Coleen L.; Jarre  Astrid; Arancibia  Hugo; Bozec  Yves-Marie; Neira  Sergio; Roux  Jean-Paul; Shannon  Lynne J. 《ICES Journal of Marine Science》2005,62(3):493-502

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Modelling effects of fishing in the Southern Benguela ecosystem   总被引：2，自引：0，他引：2  

Shannon  Lynne J.; Cury  Philippe M.; Jarre  Astrid 《ICES Journal of Marine Science》2000,57(3):720-722

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Sedimentology of the continental end‐Permian extinction event in the Sydney Basin,eastern Australia     

Christopher R. Fielding  Tracy D. Frank  Allen P. Tevyaw  Katarina Savatic  Vivi Vajda  Stephen McLoughlin  Chris Mays  Robert S. Nicoll  Malcolm Bocking  James L. Crowley 《Sedimentology》2021,68(1):30-62

Upper Permian to Lower Triassic coastal plain successions of the Sydney Basin in eastern Australia have been investigated in outcrop and continuous drillcores. The purpose of the investigation is to provide an assessment of palaeoenvironmental change at high southern palaeolatitudes in a continental margin context for the late Permian (Lopingian), across the end‐Permian Extinction interval, and into the Early Triassic. These basins were affected by explosive volcanic eruptions during the late Permian and, to a much lesser extent, during the Early Triassic, allowing high‐resolution age determination on the numerous tuff horizons. Palaeobotanical and radiogenic isotope data indicate that the end‐Permian Extinction occurs at the top of the uppermost coal bed, and the Permo‐Triassic boundary either within an immediately overlying mudrock succession or within a succeeding channel sandstone body, depending on locality due to lateral variation. Late Permian depositional environments were initially (during the Wuchiapingian) shallow marine and deltaic, but coastal plain fluvial environments with extensive coal‐forming mires became progressively established during the early late Permian, reflected in numerous preserved coal seams. The fluvial style of coastal plain channel deposits varies geographically. However, apart from the loss of peat‐forming mires, no significant long‐term change in depositional style (grain size, sediment‐body architecture, or sediment dispersal direction) was noted across the end‐Permian Extinction (pinpointed by turnover of the palaeoflora). There is no evidence for immediate aridification across the boundary despite a loss of coal from these successions. Rather, the end‐Permian Extinction marks the base of a long‐term, progressive trend towards better‐drained alluvial conditions into the Early Triassic. Indeed, the floral turnover was immediately followed by a flooding event in basinal depocentres, following which fluvial systems similar to those active prior to the end‐Permian Extinction were re‐established. The age of the floral extinction is constrained to 252.54 ± 0.08 to 252.10 ± 0.06 Ma by a suite of new Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry U‐Pb ages on zircon grains. Another new age indicates that the return to fluvial sedimentation similar to that before the end‐Permian Extinction occurred in the basal Triassic (prior to 251.51 ± 0.14 Ma). The character of the surface separating coal‐bearing pre‐end‐Permian Extinction from coal‐barren post‐end‐Permian Extinction strata varies across the basins. In basin‐central locations, the contact varies from disconformable, where a fluvial channel body has cut down to the level of the top coal, to conformable where the top coal is overlain by mudrocks and interbedded sandstone–siltstone facies. In basin‐marginal locations, however, the contact is a pronounced erosional disconformity with coarse‐grained alluvial facies overlying older Permian rocks. There is no evidence that the contact is everywhere a disconformity or unconformity.  相似文献   

Iron metal production in silicate melts through the direct reduction of Fe(II) by Ti(III), Cr(II), and Eu(II)     

Henry D. Schreiber  G.Bryan Balazs  Andrew P. Shaffer  P.Lynne Jamison 《Geochimica et cosmochimica acta》1982,46(10):1891-1901

The production of metallic iron in silicate melts by the chemical reactions, 2Ti³⁺_(melt) + Fe²⁺_(melt) → 2Ti⁴⁺_(melt) + Fe⁰_(crystal)2Cr²⁺_(melt) + Fe²⁺_(melt) → 2Cr³⁺_(melt) + Fe⁰_(crystal)2Eu²⁺_(melt)+ Fe²⁺_(melt) → 2Eu³⁺_(melt) + Fe⁰_(crystal) has been demonstrated under experimental conditions in a simplified basaltic liquid, Such reactions may occur in lunar basalts and other reduced systems, and, thus, may aid in the understanding of the reduced nature of lunar basalts. The reactions were studied in a glass-forming Na-Ca-Mg-Al-silicate composition at a melt temperature of 1250°C and an imposed oxygen fugacity at the C/CO buffer (1 atm total pressure). Microtitrations of individually-doped samples were used in the quantitative assessment of their redox ratios and for the calibration of visible and near-infrared spectral absorptions. These spectral absorptions were then applied to the evaluation of the mutual redox interactions in dual-doped samples.  相似文献   

Morphological and morphometric analysis of variation in the Zhoukoudian Homo erectus brain endocasts     

Xiujie Wu  Lynne A. Schepartz  Christopher J. Norton 《Quaternary International》2010,211(1-2):4-13

The six Zhoukoudian (ZKD) Locality 1 Homo erectus specimens derive from stratigraphic levels 11–3 with a geochronological span of approximately 0.3 Ma. This paper introduces the history of the ZKD endocasts and presents data on their morphological features and linear dimensions in order to evaluate variability in the sample over time and in the broader context of human brain evolution using a comparative sample of African and other Asian H. erectus fossils and modern Chinese males. The ZKD brains are very similar in their morphological characteristics, but there are also significant but subtle changes involving expansion of the frontal and occipital lobe breadths that correlate with the geochronology. The same is not true for general endocranial volume. The ZKD brains, together with other Asian and African H. erectus specimens, have low height dimensions and short parietal chords that distinguish them from the modern Chinese. Furthermore, the lack of geographical patterning in the fossil sample, as determined by Principal Components Analysis, provides no support for arguments advocating the splitting of H. erectus into separate taxa.  相似文献   

How much political compromise can fisheries management stand?: Premiums and politics in closed coastal fisheries     

Lynne Chatterton  Brian Chatterton 《Marine Policy》1981,5(2):114-134

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Hydrocarbons generated by hydropyrolysis of suspended marine particulate organic matter: Relationship to the oceanography of the Black Sea and the Rhodes Gyre     

Yeşim Çoban-Yildiz  Alec F. Gaines  Pat E. Keating  Gordon D. Love  Dennis McLoughlin  Colin E. Snape 《Organic Geochemistry》2009,40(2):270-282

The suspended particulate organic matter, SPOM, in the autumnal Black Sea has been characterised using catalytic hydropyrolysis (HyPy) of the total (bound plus free) lipid material. The technique, which generates maximum yields of volatile products from sediments, kerogens and phytoplankton, was followed using gas chromatography and gas chromatography/mass spectrometry. The generated alkanes were dominated by n-C₁₈, hypothesised to arise predominantly from unsaturated C₁₈ fatty acids. Steranes were generated from reductive conversion of free and bound sterols. The generation of branched alkanes and especially of hopanes provided formal evidence for the participation of bacteria in the mineralisation of the SPOM. Whereas similar distributions of n-alkanes were generated from SPOM sampled from different depths of the comparatively well-stirred Rhodes Gyre (eastern Mediterranean), mineralisation of the SPOM at each depth of the central Black Sea produced characteristic changes in the composition and concentration of the HyPy products. Depth profiles of the n-alkanes generated from SPOM in the region of the Rim Current were affected by the local hydrography. Polynuclear aromatic hydrocarbons (PAHs) of anthropogenic origin were present in the surface waters of the central Black Sea. Some methyl benzenes, thiophenes and pyrroles were also generated.  相似文献