Abstract

Temperature (T in °C) and mean vitrinite reflectance (Rm in %) of sedimentary organic matter samples from six liquid-dominated geothermal systems plot about a line approximated by a regression equation of the form Rm = 0.435 exp 0.00683T. The reflectance data from these systems are strongly temperature-dependent, with a coefficient of determination (r2) of 0.8. Geologic evidence indicates that reaction duration ranges from 103 or 104 to 106 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 Rm indicates that after about 104 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.

First Page Preview

First page PDF preview
You do not currently have access to this article.