重庆云阳晚三叠世—侏罗纪古流向反转及其构造意义  

Reversion of paleocurrent directions and its tectonic significance in the Late Triassic and Jurassic period in Yunyang,Chongqing

作　　者：屈红军[1] 董云鹏[1] 马强[1] 查显锋[1] 徐子炎[1] 

机构地区：[1]西北大学大陆动力学国家重点实验室/地质学系,陕西西安710069

出　　处：《西北大学学报（自然科学版）》2009年第3期528-532,共5页Journal of Northwest University（Natural Science Edition）

基　　金：中石化前瞻性基金资助项目

摘　　要：目的探讨大巴山逆冲推覆作用与江南—雪峰逆冲推覆作用在川东地区的复合或联合构造作用的时序,进而分析大巴山前陆盆地的强烈沉降时期。方法以详细的野外剖面测制为基础,通过对重庆云阳南溪上三叠统—侏罗系剖面沉积序列及古流向的详细研究,确定晚三叠世—侏罗纪沉积体系及物源方向的演化规律,进而探讨大巴山逆冲推覆作用与江南—雪峰逆冲推覆作用在川东地区的影响时序的差异性。结果重庆云阳南溪上三叠统发育辫状河沉积体系,古流向向南,而中下侏罗统主要发育湖泊及三角洲沉积体系,古流向向北或西北,两时期古流向发生了反转。结论川东地区大巴山逆冲推覆作用早于江南—雪峰逆冲推覆作用,中侏罗世中晚期为大巴山前陆盆地强烈沉降期。Aim To discuss compound or joint tectonic influence of sequence of thrust napping between Daba Mountain and jiangnan-Xuefeng Mountain in Chuandong area and analysis period of intense subsidence of Daba foreland basin. Methods On the basis of measurement of field section, detailed research of profile depositional sequence and paleocurrent direction of the Upper Triassic and Jurassic system in Nanxi, Yunyang , Chongqing can confirm evolutionary regularity of depositional system and provenance direction in Late Triassic and Jurassic period , and then to discuss the difference of sequence influence between Daba Mountain and jiangnan and Xuefeng Mountain thrust napping in Chuandong area. Results The Upper Triassic in Yunyang, Chongqing develops depositional systems of braided stream with paleocurrent direction points to south;however, the Lower-Middle Jurassic develops mainly depositional systems of lake and deltas, with paleocurrent direction pointing to north or northwest, therefore, paleocurrent direction reverses in the two periods. Conclusion Thrust napping of Daba Mountain is earlier than the thrust napping of Jiangnan-Xuefeng Mountain , and the intense subsidence of foreland basin of Daba Mountain takes place in Middle to Late of the Middle Jurassic.

关 键 词：古流向 沉积体系 大巴山前陆盆地 云阳南溪 晚三叠世-侏罗纪 

分 类 号：P534.51[天文地球—古生物学与地层学] TL364.1[天文地球—地质学]