辽河盆地东部凹陷热历史及构造—热演化特征

THERMAL HISTORY AND TECTONO THERMAL EVOLUTION OF EASTERN DEPRESSION,THE LIAOHE BASIN

根据辽河盆地东部凹陷大地热流测量和镜质体反射率数据 ,恢复了该区的热历史 ,结果表明 :东部凹陷热流呈现古热流高现今热流低的变化特征 ,沙河街组三段沉积期到东营组沉积期 (距今 43～ 2 5Ma)盆地热流为 66～ 82mW m2 ,现今热流值为 47～ 70mW m2 。构造沉降史分析显示 ,盆地经历了早期的裂谷阶段 (距今 43～ 2 5Ma)和后期的热沉降阶段 ,裂谷阶段包含了两个裂谷亚旋回。盆地现今较低的大地热流和较高的古热流及典型的裂谷型构造沉降样式为东部凹陷的构造—热演化提供了重要认识。

Based on heat flow measurements and vitrinite reflectance ( R o) data, the geothermal history of Eastern Depression of the Liaohe Basin was reconstructed, which indicated that the Eastern Depression was characterized by lower present day heat flow varying between 47～70 mW/m 2, and that the depression experienced a much higher heat flow (66～82 mW/m 2) period from 43 Ma to about 25 Ma ago. The structural subsidence analysis showed that the subsidence of Eastern Depression could be divided into two phases: the earlier (25～43 Ma ago) initial (rift) subsidence and late (since 25 Ma ago) thermal subsidence. The earlier rift phase was composed of two sub rift episodes with rapid subsidence. The lower present day heat flow and the higher palaeo heat flow corresponding to structural subsidence stage as well as the typical rift subsidence style in the Eastern Depression provided with some insight to the tectono thermal evolution of the basin.