Thermal and maturation history of Jurassic source rocks in the Kuqa foreland depression of Tarim Basin, NW China

Abstract

Kuqa foreland depression of the Tarim Basin is one of the largest gas production provinces in China. Thermal history reconstruction using vitrinite reflectance data indicates that the palaeo-heat flow in Kuqa depression was relatively high (50–55mW/m2) during the Mesozoic, but gradually decreased during the Cenozoic to reach the present value of 40–50mW/m2. The cooling of the Kuqa depression is probably attributed to the crust thickening and the rapid sedimentary rate. The Jurassic source rocks entered conventional oil window at 100Ma, and began to generate gas at approximately 75Ma in the Kelasu area. Thermal maturation of the Jurassic source rocks accelerated significantly since 23.3Ma, especially in the recent 5.2Ma. In this foreland depression, source rock maturation, which is likely controlled mainly by burial history, also influenced by the presence of fault thrusting and salt-bearing formations.