柴达木盆地西部新生代的构造-热演化研究

TECTONO-THERMAL EVOLUTION OF WESTERN QAIDAM BASIN, NORTHWEST CHINA

利用磷灰石裂变径迹 (AFTA)参数和镜质体反射率动力学模型对柴达木盆地西部地区的构造—热演化进行系统分析 ,通过对 1 0个构造部位 1 6口井的单井热历史模拟分析了该区新生代的热演化状况。研究表明柴达木盆地西部地区的地温梯度在第三纪以来随着盆地的演化逐渐减小 ,但在第四纪以来变化不大或有增加的趋势 ;热流的变化与地温梯度的变化不同 ,随地史的演化逐渐增加。该区热流的这种变化与构造演化密切相关 ,盆地第三纪末(N32 )以后发生的新构造运动 (有人称喜马拉雅运动第三幕 )是造成现今地温分布状况的根本原因。

Apatite fission track analysis(AFTA) and kinetic model of vitrinite reflectance(Ro) are applied to be the paleogeothermometers to analyse the thermal-tectonic evolution of the Western Qaidam Basin. By the modeling of thermal history from 16 wells, the thermal evolution status since the Tertiary time in this area was obtained. The thermal gradient decreased from the Tertiary time, but changed a little during the Quaternary. However, heat flow evolution during the Cenozoic time is special with that of thermal gradient. Heat flow increased gradually from Tertiary, which is correspond to the structural evolution by the erosion of strata. This study is the first time to analyse, systematically, heat flow evolution of the Qaidam Basin, which will be useful to the hydrocarbon resources assessment in the basin.