雅布赖盆地萨尔台凹陷中—新生代构造热事件的磷灰石裂变径迹分析

Apatite fission track analysis of Meso-cenozoic tectonic-thermal history in Sartai depression, Yabrai Basin

运用磷灰石裂变径迹（AFT）分析方法,探讨分析雅布赖盆地萨尔台凹陷中—新生代构造热事件发生的径迹年龄（AFTA）和长度（AFTL）分布特征,并通过反演法建立热史模型,恢复构造热演化过程。研究结果表明：研究区可能至少经历了3期隆升过程,分别发生在晚侏罗世末期（（138.0±10）-135.8 Ma）、早白垩世晚期（（116.0±8）-109.3Ma）和古近纪中晚期（52.0-29.4 Ma）。在时间演化上,新河组下段（J2x1）地层在盐场次凹和小湖子次凹具有相似性,但后者地层温度普遍高于前者,尤其在早白垩世,拥有更利于油气生成的地温环境。发生在180.0-146.7 Ma和130.5-100.0 Ma期间的2次增温过程与烃源岩热演化关系密切,地层温度可加热至72.0-135.0℃,是影响油气生成的关键阶段。构造热演化过程的研究为雅布赖盆地萨尔台凹陷的石油、天然气等矿产资源的勘探提供了新的约束条件。

The characteristics of apatite fission track age（AFTA） and length（AFTL） data of the Meso-cenozoic tectonic-thermal history of Sartai depression of Yabrai basin were revealed by apatite fission track analysis. And the thermal history model was established by inversion method to recover the tectonic-thermal evolution. The results show that the study area may have experienced three times of uplift process at least which occurred in the end of Jurassic（（138.0±10）-135.8 Ma）, late stage of Early Cretaceous（（116.0±8）-109.3 Ma） and middle-late Paleogene（52.0-29.4 Ma）. The J2x1 strata in Yanchang sub-sag and Xiaohuzi sub-sag have the similar thermal evolution process in time, but the temperature of J2x1 in Xiaohuzi sub-sag is generally higher than that in Xiaohuzi sub-sag, especially in the Early Cretaceous when Xiaohuzi sub-sag had a much better geothermal field environment for hydrocarbon generation. The temperature of J2x1 heats up to 72.0-135.0 ℃ during 180.0-146.7 Ma and 130.5-100.0 Ma, and the two warming processes are the crucial stages of the source rock＇s maturity evolution and hydrocarbon generation in study area. The study of tectonic-thermal history can provide some new constraints on oil-gas and other mineral exploration in Yabrai Basin.