Effects of Geological Parameters on Temperature Histories of Basins

Arif M. Yukler and Tufan L. Erdogan

Subsidence, depositional environment, type of sediments, sedimentation and erosion rates, duration of non-deposition and tectonic movements are the most important parameters in the quantification of temperature histories. To determine a near-unique temperature history, one knows the present temperature and estimates the initial value based on depositional environment and paleo-climate data. The effects of these parameters are amplified in a rapidly subsiding basin, such as the Kura Basin in Azerbaijan. High sedimentation rates result in formation of abnormal pressures and under-compaction and retard the heat transfer through sediments by lowering their thermal conductivities. As the system tries to reach hydrostatic conditions, sediments lose heat by conduction and advect on. Our studies over the last twenty years have shown that the pressure changes are instantaneous as the result of the sediment loading, whereas temperature responds with a time lag. High erosion rates may cause subnormal pressures and partial decompaction of sediments. In fine sediments, fluids may not flow into the sediments at the rate of formation of subnormal pressures and this results in the collapse of these sediments. The heat content of the fluids may cause heating or cooling of the subnormally pressured sediments.

Non-deposition periods allow the abnormally and subnormally pressured sediments to reach hydrostatic conditions and decrease the time lag for heat response within the sediments.

Thrusting generally results in abnormal pressure formation, but the geothermal gradients are less than the ones in the systems overlain by regular sediments.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California