鄂西渝东方斗山-石柱褶皱带中新生代隆升剥蚀过程及构造意义  

Exhumation Process of the Fangdoushan-Shizhu Fold Belt in Meso-Neozoic and Its Tectonic Significance in Western Hubei-Eastern Chongqing

作　　者：石红才[1,2] 施小斌[1] 杨小秋[1] 蒋海燕[1,2] 龙幼康[3] 

机构地区：[1]中国科学院边缘海地质重点实验室,南海海洋研究所,广州510301 [2]中国科学院研究生院,北京100049 [3]江汉油田分公司勘探开发研究院,潜江433124

出　　处：《地球物理学进展》2011年第6期1993-2002,共10页Progress in Geophysics

基　　金：中石化前瞻性项目(5220589);中国科学院边缘海地质重点实验室基金项目(MSGL09-08);国家高技术研究发展计划(863计划)项目(2009AA09A201-05)联合资助

摘　　要：利用磷灰石与锆石(U-Th)/He年龄与磷灰石裂变径迹(AFT)、镜质组反射率(Ro)一起模拟了鄂西渝东方斗山-石柱褶皱带侏罗纪以来的构造热演化特征.结果表明:在约130 Ma(晚侏罗世-早白垩世)研究区达到最高古地温,此后为持续抬升冷却过程.磷灰石裂变径迹与Ro表明自晚侏罗世以来不整合面剥蚀厚度可达3500 m.结合(U-Th)/He与Ro数据的反演结果揭示自约130 Ma开始抬升冷却后可分为三个构造演化阶段:快速冷却一缓慢冷却-快速冷却,在晚侏罗世晚白垩世(±130～70 Ma)抬升冷却速率为0.75～1.0℃/Ma;晚白垩世到始新世晚期(70～45 Ma)为较平静期,冷却速率为0.33～0.4℃/Ma;自始新世末(±45 Ma)以来冷却速率为0.9～1.1℃/Ma.它们分别与中上扬子三叠纪以来的三次重要构造变革时期相对应,这为造山带构造演化分析提供有力佐证.The exhumation history of Fangdoushan-Shizhu fold belt in the Western Hubei-Eastern Chongqing since Jurassic was modeled by using combined vitrinite reflectance and apatite and zircon （U-Th）/He and apatite fission track dating methods. The results show that all samples have experienced the highest paleogeotemperature in the study area during the late Jurassic-the early Cretaceous, and from then on, the study area was always to drop in paleogeotemperature. According to the ages of apatite fission track and Ro, the denudation may be reach 3500 m during the surface of unconformity in Mesozoic-Cenozoic period. Besides, combining with the results of （U-Th）/He method and vitrinite reflectance, we can get a further understanding： three tectonic phases have been revealed in the whole： rapid cooling-slow cooling-fast cooling, during the first phase, the cooling speed is about 0.75-1.0℃/Ma from the late Jurassic to the late Cretaceous （about130-70Ma）, following a quiet phase with the cooling speed of 0.33-0.4℃/Ma during the late Cretaceous to the end of Eocene （about 70-45 Ma）, the final phase reach the maximum cooling speed which is about 0. 9-1. 1℃/Ma lasting from Eocene to now（about 45Ma）,the three phases are correspondent with the period of three important structural changes since Middle-Trassic in the Middle-upper Yangtze. The test proves an evidence to the analysis of tectonic evolution of orogenic.

关 键 词：构造-热演化 鄂西渝东 (U-Th)/He 裂变径迹 镜质组反射率 

分 类 号：P541[天文地球—构造地质学] P314[天文地球—地质学]