Present-Day Heat Flow, Thermal History, and Tectonic Subsidenceof the Jianghan Basin

Abstract

Thermal gradient distribution of the Jianghan Basin is obtained based on systematic steady-state and oil-test temperature data. The present geothermal gradient and terrestrial heat flow of 18 wells are calculated in the Jianghan Basin. A total of 9 measured terrestrial heat flow values are reported based on detailed thermal conductivity data and systematic steady-state temperature data. These values vary from 41.9 to 60.9 mW/m2, with a mean value of 52.3 ± 6.3 mW/m2. However, thermal history analyses, derived from vitrinite reflectance (RO) and apatite fission track (AFT) data, indicate that the Jianghan Basin was at a stable stage before the Indosinian movement. The heat flow increased and reached its maximum value of ∼68 mW/m2 during the Late Indosinian to Early Yanshan period. Since the Late Himalayan period, rapidly decreasing basement heat flow made the Jianghan Basin cool down. Furthermore, geohistory analysis reveals that the tectonic subsidence of the Jianghan Basin from the Cretaceous to Early Miocene was characterized by initial synrift subsidence followed by thermal subsidence. The thermal and tectonic subsidence history have directly effects on petroleum source rock maturation, so their analyses are of great significance forpetroleum exploration and hydrocarbon source assessment in the Jianghan Basin.