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Influence of time on metamorphism of sedimentary organic matter in liquid-dominated geothermal systems, western North America

C.E. Barker
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Abstract

Temperature ( T in °C) and mean vitrinite reflectance ( R m in %) of sedimentary organic matter samples from six liquid-dominated geothermal systems plot about a line approximated by a regression equation of the form R m = 0.435 exp 0.00683 T . The reflectance data from these systems are strongly temperature-dependent, with a coefficient of determination ( r 2 ) of 0.8. Geologic evidence indicates that reaction duration ranges from 10 3 or 10 4 to 10 6 yr in these systems that appear to have near-maximum temperatures. The uncertainty in vitrinite reflectance and temperature determinations must account for a large part of the remaining variability not explained by the regression equation; therefore, the strong temperature dependence of R m indicates that after about 10 4 yr, reaction duration has little or no influence on metamorphism of organic matter in liquid-dominated geothermal systems. These data indicate that vitrinite reflectance can be used to determine the maximum temperature reached in hot sedimentary basins of moderate longevity.

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C.E. Barker. 1983. Influence of time on metamorphism of sedimentary organic matter in liquid-dominated geothermal systems, western North America. https://doi.org/10.1130/0091-7613(1983)11%3C384%3Aiotomo%3E2.0.co%3B2

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