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George E. Claypool

Publications and source records attributed to George E. Claypool.

26 records · Page 2Linked to original sources
USGS1980

The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation

Three hundred new samples of marine evaporite sulfate, of world-wide distribution, were analyzed for δ 34 S, and 60 of these also for δ 18 O in the sulfate ion. Detailed δ 34 S age curves for Tertiary—Cretaceous, Permian—Pennsylvanian, Devonian, Cambrian and Proterozoic times document large variations in δ 34 S. A summary curve forδ 18 O also shows definite variations, some at different times than δ 34 S, and always smaller. The measured δ 34 S and δ 18 O correspond to variations in these isotopes in sulfate of the world ocean surface. The variations of δ 18 O are controlled by input and output fluxes of sulfur in the ocean, three of which are the same that control δ 34 S: deposition and erosion of sulfate, and deposition of sulfide. Erosion of sulfide differs in its effect on the S and O systems. δ 18 O in the sulfate does not seem to be measurably affected by equilibration with either seawater or with subsurface waters after crystallization. In principle, the simultaneous application of both δ 34 S and δ 18 O age curves should help reduce the number of assumptions in calculations of the cycles of sulfur and oxygen through geological time, and a new model involving symmetrical fluxes is introduced here to take advantage of the oxygen data. However, all previously published models as well as this one lead to anomalies, such as unreasonable calcium or oxygen depletions in the ocean—atmosphere system. In addition, most models are incapable of reproducing the sharp rises of the δ 34 S curve in the late Proterozoic, the Devonian and the Triassic which would be the result of unreasonably fast net sulfide deposition. This fast depletion could result from an ocean that has not always been mixed (as previously assumed in all model calculations).

Chemical Geology↗
USGS1980

Organic composition of some Upper Cretaceous shale, Powder River Basin, Wyoming

The lower Upper Cretaceous strata in northeastern Wyoming, which have yielded major quantities of oil and gas, were sampled at boreholes in Converse, Johnson, and Weston Counties. Cores of noncalcareous shale of largely nearshore-marine origin were obtained from the Frontier Formation and the overlying Cody Shale at depths of 3,780.6 to 3,879.9 m in Converse County, near the axis of the Powder River basin, and at depths of less than 320 m in Johnson County, on the western flank of the basin. Cores of calcareous and noncalcareous shale representing offshore-marine and nearshore-marine environments were acquired from the Belle Fourche Shale, Greenhorn Formation, and Carlile Shale at depths of less than 270 m in Weston County, on the eastern flank of the Powder River basin. Analyses of the shale for organic carbon content, total pyrolytic hydrocarbon yield, volatile hydrocarbon content, temperature of maximum pyrolytic yield, and vitrinite reflectance indicate that the amount and character of the organic matter in the sampled rocks is related to the content of calcium carbonate, the depositional environment, and the burial depth of the strata. On the east flank of the Powder River basin, calcareous shale of offshore-marine origin contains abundant hydrogen-rich organic matter derived mainly from aquatic plants. Noncalcareous shale of largely nearshore-marine origin, on the west flank of the basin, locally contains significant hydrogen-poor organic matter derived mostly from land plants. The noncalcareous, nearshore-marine shale in the middle of the basin probably contained similar amounts of hydrogendeficient organic matter prior to deep burial and thermal alteration. The calcareous shale in Weston County is a potentially rich source of oil and gas, but it is thermally immature and is in a very early stage of the hydrocarbon-generation process. The noncalcareous shale in Johnson County is a potential source rock for gas, but also is in an early stage of thermal alteration. In Converse County, the sampled beds are thermally mature and have generated hydrocarbons. The extent of this contribution of hydrocarbons to the commercial petroleum occurrences of the area can be inferred from the composition of the original organic matter in the beds. Furthermore, the degree of thermal alteration of the organic matter at these localities indicates that the depth of the sampled strata was never as great on the flanks of the Powder River basin as in the basin center.

Wyoming↗
USGS1980

Origin of gasoline-range hydrocarbons and their migration by solution in carbon dioxide in Norton basin, Alaska.

Carbon dioxide from a submarine seep in Norton Sound, Alaska, carries a minor component of gas- and gasoline-range hydrocarbons. The molecular and isotopic compositions of the hydrocarbon gases and the presence of gasoline-range hydrocarbons indicate that these molecules are derived from thermal alteration of marine and/or nonmarine organic matter buried within Norton basin. In the gasoline-range hydrocarbons, individual cyclic and branched-chain molecules are much more abundant than straight-chain hydrocarbons. This distribution suggests that the hydrocarbon mixture is an immature, petroleumlike condensate of lower temperature origin than normal crude oil. The submarine seep provides a natural example in support of a carbon dioxide solution transport mechanism thought to be operative in the migration of hydrocarbons in certain reservoirs.

Alaska↗