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Xuejing XIE Mingcai YAN Chunshu WANG Lianzhong LI Huijun SHEN 《Geostandards and Geoanalytical Research》1989,13(1):83-179
The 18 Chinese geochemical standard reference samples GSD 9-12 (stream sediments), GSS 1-8 (soils) and GSR 1-6 (rocks) were prepared after GSD 1-8 (stream sediments) for even wider and increasing needs of geology, exploration geochemistry and geochemical analysis. Usable values of 41 trace, minor and major elements of the 18 samples were published in 1984. In the following two years, efforts were concentrated on the determination of other elements, most of which are more difficult to determine accurately and hence not many data were available in the literature. At the same time, additional data on the 41 elements already evaluated were also submitted. In all, 155 234 results were available along with the 35 284 analytical data submitted. The processing of samples, the examination of sample homogeneity, the plan of collaborative analysis of the samples, and the criteria for defining the recommended values are described. The recommended or reference values of the 72 constituents, to-gether with the 35 284 analytical data of the 18 samples are published in this paper. 相似文献
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Trevor D. Ford 《Geology Today》2002,18(3):100-107
Among the late 18th-century pioneers of geological science was John Whitehurst. He set the scene for the early Derbyshire geologists, White Watson and John Farey, whose books were not published until 1811, long after Whitehurst's death. But Whitehurst's ideas went beyond Derbyshire; he looked at the global situation in his book An Inquiry into the Original State & Formation of the Earth (1778, 1786). Whitehurst was a founder member of the influential Lunar Society and a close friend of many philosophers of the period. 相似文献
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Richard A. Reyment 《地学学报》1991,3(2):221-223
A new series presenting vignettes of the life and times of early notables, confirming the fact that all is not milk and honey in the pursuit of knowledge, 相似文献
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Christopher J. Duffin 《Geology Today》2006,22(3):104-108
This year marks the 150th anniversary of William Buckland's death. One of the liveliest characters in the early history of our science, Buckland was a keen observer, indefatigable scholar, enthusiastic field geologist, inspirational communicator and possessed of an innovative mind which could quickly embrace, process and apply new ideas. His influence on an emerging discipline during its arguably most formative years in the early nineteenth century, and upon subsequent generations of Earth science scholars, should not be underestimated. 相似文献
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John T. Andrews R. Kihl Greta B. Kristjansdottir L. M. Smith Gudrun Helgadottir† Aslaug Geirsdottir‡ & Anne E. Jennings 《Sedimentology》2002,49(1):5-24
The oceanographic Polar Front separates the East Greenland and Iceland margins. Surface water temperatures across Denmark Strait vary by 8–12 °C and represent one of the steepest oceanographic gradients on earth. The East Greenland margin is a polar environment, with extensive sea‐ice cover and calving glacier margins; in contrast, the Iceland shelf is much more temperate, and freshwater run‐off is a key component in land–ocean sediment transfers. Average sediment properties from these two contrasting climate and oceanographic continental shelf environments are compared in the spatial domain at 13 sites; the data represent the last 10 000 radiocarbon years of `normal' marine sedimentation for the two regions. The two regions have similar average rates of sediment accumulation (around 43·5 cm kyr?1), so that this key variable is factored out in explaining any differences in sediment properties. Dry sediment density, moisture content, hygroscopic moisture, total organic carbon and carbonate contents, mass magnetic susceptibility and the percentages of sand and silt are compared focusing on: (1) median values for sediment properties; and (2) downcore variability, measured by the coefficient of variation (CV). There are significant differences in all but one (hygroscopic moisture) of the sediment properties between Iceland and East Greenland; in four cases, the sense of the differences was not as predicted. In terms of downcore variation (CV), no difference was found between the two regions, nor between the 13 sites, whereas there are some significant differences between the variables. Carbonate and mass magnetic susceptibility have the largest spreads, and moisture content and dry sediment density are the least variable. Protocols are developed to identify the `type core' in a regional series of sites. The results indicate a need to develop a regional perspective on sediment properties, both as inputs to models of sedimentary processes in different polar/arctic environments, and as an indication of which sediment properties might be best suited for palaeoenvironmental downcore time series. 相似文献
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《Quaternary Research》1982,18(2):127-143
Decreases in surface temperatures after the eruptions of Tambora (1815), Krakatau (1883), and Agung (1963) were of similar magnitude, even though the amount of material (dust and volatiles) injected into the stratosphere by these three events differed greatly. Large amounts of fine ash and volatiles were dispersed into the upper atmosphere by Krakatau and Tambora; the Agung eruption in 1963 was a much smaller, vulcanian-type eruption which injected dust and volatiles into the stratospheric aerosol layer more directly. Analyses of magmatic volatiles indicate that the Agung eruption was proportionately richer in SO2 and Cl than either Tambora or Krakatau. Relative amounts of fine ash produced by the Tambora, Krakatau, and Agung eruptions are estimated at about 150:20:1, whereas the masses of atmospheric sulfate aerosols produced were on the order of 7.5:3:1.Decreases in surface temperature of a few tenths of a degree C for several years following volcanic eruptions are primarily a result of the sulfate aerosols, rather than of the silicate dust. The similarity in the atmospheric response after these three eruptions supports the idea of limiting mechanisms on volcanic stratospheric-aerosol loading, which is suggested by microphysical processes of aerosol particles. Fluctuations in stratospheric aerosol optical depth seem to be controlled to a large degree by high-intensity sulfur-rich eruptions (e.g., Agung, 1963), which may however be relatively small in total ejecta volume. Such eruptions leave little geologic record, but appear as acidity peaks in polar ice cores. 相似文献
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William Dubbin 《Geology Today》2001,17(6):225-228
'Lying at the interface of the geosphere, biosphere and hydrosphere, soils occupy a central place in ecosystems, and because of this they are sensitive and detailed indicators of past and present environments.' 相似文献
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Sequence architecture and carbonate platform configuration (Late Cenomanian–Santonian), Sinai, Egypt
Abstract Relative sea‐level changes on the mixed carbonate–siliciclastic platform of Sinai are manifested in shifts of distinct facies belts (deep‐water facies, high‐energy subtidal, shallow subtidal, lagoon, shallow shoreface siliciclastics, supratidal) and are interpreted in terms of sequence stratigraphy. Eight sedimentary sequences are recognized for the Upper Cenomanian to Santonian. Their correlation along a north–south transect reveals distinct changes in lithofacies and progradation/retrogradation patterns within the individual systems tracts. The number and stratigraphy of the sequence boundaries of Sinai correlate well with those from adjacent areas. Patterns of increased subsidence are documented for the Central Sinai Basin since the Late Cenomanian by increased thickness of the stratal packages (post‐CeSin 7 HST, post‐TuSin 1 LST and HST, post‐TuSin 2 LST) and are balanced by varying accumulation rates. Based on new sedimentological and biostratigraphic data, large‐scale palaeogeographic maps and cross‐sections show the: (1) temporal and spatial evolution of the Central Sinai Basin, e.g. its latest Cenomanian initial formation, Lower Turonian deep‐water facies, Middle Turonian to Coniacian synsedimentary subsidence; (2) drowning of the Cenomanian platform coinciding with the latest Cenomanian to Early Turonian relative sea‐level rise; (3) re‐establishment of the platform in Middle–Late Turonian times; and (4) a Coniacian basin and swell morphology. 相似文献
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Alan C. Kendall 《Sedimentology》2000,47(1):151-171
Halite-impregnated carbonates in the Dawson Bay Formation of Saskatchewan lie between beds of halite and are buried to a depth of 1 km. They exhibit two different diagenetic styles – some resisted compaction and had high pre-salt porosities; others contain compaction-broken fossils and pressure-solution seams. The uncompacted rocks, together with the difficulty of explaining how halite cement could enter the Dawson Bay after overlying bedded halites were deposited, suggest that halite cementation occurred early with only a few tens of metres of overburden. Early diagenetic compaction is suggested by the presence of unbroken, displacive skeletal halite crystals, which cross-cut compaction structures, and by the difficulty of explaining how (1) later compaction could occur in halite-cemented rocks and (2) how pore-fluids could be expelled after surrounding rocks lost their permeability. The organic-rich nature of many carbonates may explain why compaction was both early and extensive, but this explanation fails to explain how similar compaction developed in horizons with lower organic contents. Chemical compaction may also have been enhanced by aragonite dissolution during seawater evaporation or brine dilution. Early chemical compaction in Dawson Bay carbonates indicates that compaction in other carbonates need not signify deep burial diagenesis; neither can compaction be used indiscriminately to identify other diagenetic events as being of deep burial origin. Early halite cementation, as in the Dawson Bay Formation, preserves carbonates at early diagenetic stages and may thus preserve geochemical information unmodified by later diagenesis. 相似文献