柴达木盆地东部古生代以来构造-热演化  

The tectono-thermal evolution in the eastern Qaidam Basin,Northwest China since the Paleozoic

作　　者：李宗星[1,2,3] 邱楠生[1,2] 马寅生[3] 郭迎春[3] 肖勇军[4] 赵为永[5] 

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)盆地与油藏研究中心,北京102249 [3]中国地质科学院地质力学研究所页岩油气调查评价中国地质科学院重点实验室,北京100081 [4]中国石化胜利油田分公司勘探开发研究院西部分院,山东东营257000 [5]中石油青海油田分公司勘探开发研究院,甘肃敦煌736202

出　　处：《地学前缘》2017年第3期157-167,共11页Earth Science Frontiers

基　　金：国家自然科学基金项目(41302202);中国地质科学院地质力学研究所基本科研项目(DZLXJK201305);中国地质调查局地质调查项目(1212011120964)

摘　　要：柴达木盆地是我国西部三大含油气盆地之一,经历了多期叠加与改造。盆地构造-热演化史研究一方面对分析柴达木盆地的构造成因,揭示青藏高原的形成机制和隆升历史有重要的意义,另一方面为盆地进行油气资源评价提供科学依据。采用平衡剖面技术、磷灰石裂变径迹年龄分布特征定性分析与径迹长度分布数据定量模拟相结合的方法,分析了柴达木盆地东部古生代以来的构造演化过程,研究表明:柴达木盆地东部在侏罗纪早期构造活动强烈,导致了石炭系抬升、剥蚀;白垩纪末期构造运动相对较弱,表现为早期的弱伸展与晚期北东-南西向的挤压;喜山运动在该区域多期发育,主要为喜山运动早期(41.1~33.6Ma)、喜山运动晚期(9.6~7.1 Ma,2.9~1.8 Ma),其中晚喜山运动造成了先存断裂的再次活化。在埋藏史重建的基础上,对柴达木盆地东部热历史进行了恢复,结果表明柴达木盆地东部热历史总体变现为缓慢降低的特征,古生代末期柴达木盆地东部古地温梯度为38~41.5℃/km,地温梯度平均值为39℃/km;古近纪早期地温梯度降为29~35.2℃/km,平均值为约33.0℃/km,古近纪末地温梯度有所变大,新近纪末趋于现今的热状态。柴达木盆地东部古生代以来构造-热演化特征主要受控于研究区岩浆热事件发育与构造活动的特征。The Qaidam Basin, one of the three major petroliferous basins in western China, experienced multiphase superimposition and transformation. Tectono-thermal evolution study, therefore, plays an important role in analyzing the tectonic origin of the basin in order to understand the formation mechanism and uplift history of the Tibetan plateau; it also provides scientific evidence for appraising oil ＆ gas resources. Using the equilibrium profile technique, combined with age analysis of apatite fission tracks by track length distribution modeling, it was inferred that the eastern Qaidam Basin experienced significant tectonic movement in the early Jurassic （-200 Ma）, causing the carboniferous uplift and denudation. In contrast, the geological movement was relatively weak in the Late Cretaceous, characterized by the weak stretch and northeast-southwest extrusion in the Early and Late Cretaceous, respectively. The Himalayan movement in the eastern Qaidam Basin was thought to be multi-stage and can be divided mainly into the early （41.1 - 33. 6 Ma） and late （9. 6 - 7. 1 Ma, 2. 9 - 1.8 Ma） Himalayan movements, where large-scale orogeny induced reactivation of the preexisting faults in the late H/malayan movement. Upon burial history reconstruction, thermal history of the eastern Qaidam Basin was restored. It shows that the overall thermal history has the characteristics of slow cooling; the paleo-geothermal gradients in the basin were 38 - 41.5 ℃/km in the Late Paleozoic with an average of 89. 0 ℃/km, and 29 - 35.2 ℃/km in the Early Paleogene with an average of 3a. 0 ℃/km. The geothermal gradient in the basin increased in the Late Paleogene and was similar to the present value in the Late Neogene. The study concludes that the tectono-thermal evolution in the eastern Qaidam Basin since the Paleozoic was mainly controlled by the magmatic thermal events and tectonic activity in the study area.

关 键 词：构造-热演化 平衡剖面 裂变径迹 柴达木盆地东部 

分 类 号：P314[天文地球—固体地球物理学]