西秦岭北缘漳县新生代伸展断陷盆地确定及其地质意义

发布时间：2018-08-01 10:11

【摘要】：西秦岭北缘断裂带新生代以来挤压逆冲变形起始于何时?挤压逆冲变形之前是否经历过伸展拉张过程?北缘断裂带北侧的新生代红层盆地到底是类前陆压陷挠曲盆地还是拉张断陷盆地?上述问题对西秦岭新生代盆-山构造格局重建和印度-欧亚板块碰撞汇聚的远程构造响应的时间与方式等科学问题的认识具有重要的地质约束。本文通过对西秦岭北缘构造带内漳县渐新世—中新世含盐红层盆地沉积序列和沉积旋回特征以及盆地边界断裂之间的几何学-运动学关系分析,认为西秦岭北缘构造带内漳县含盐红层盆地具有拉张伸展动力学背景下形成的断陷盆地的地质特征。西秦岭北缘构造带内渐新世—中新世断陷盆地的确定,指示了印度板块与欧亚板块碰撞汇聚而导致的青藏高原构造挤压缩短作用至少在盆地沉积充填阶段尚未扩展到西秦岭北缘及以北地区。而漳县含盐红层盆地沉积地层褶皱缩短变形以及之后角度不整合在漳县含盐红层盆地之的上新统韩家沟粗砾岩,可能记录了西秦岭北缘由伸展边界向挤压缩短逆冲边界的转换过程。因此,青藏高原东北缘真正成为青藏高原体系组成部分是在上新世的漳县含盐红层盆地封闭-构造反转之后。这一认识对地学界长期以来认为印度板块与欧亚板块碰撞汇聚而导致的高原隆升和构造挤压早在渐新世就已经波及西秦岭北缘的观点提出了挑战。
[Abstract]:When did the compressional thrust deformation begin in the northern margin of the West Qinling fault zone since the Cenozoic? Has the process of stretching and stretching been experienced before the extrusion thrusting? Is the Cenozoic red bed basin on the north side of the northern margin fault zone a Foreland depression flexural basin or a extensional fault basin? These problems have important geological constraints on the reconstruction of Cenozoic basin-mountain tectonic pattern in the West Qinling Mountains and the time and mode of the remote tectonic response of the India-Eurasian plate collision convergence. In this paper, the sedimentary sequence and sedimentary cycle characteristics of Oligocene to Miocene salt-bearing red bed basins in the northern margin of West Qinling are analyzed, as well as the geometer-kinematic relationship between the boundary faults of the basins. It is considered that the Zhangxian salt-bearing red bed basin in the northern margin of the western Qinling Mountains has the geological characteristics of the faulted basin formed under the background of extensional dynamics. The determination of Oligocene and Miocene faulted basins in the northern margin of the West Qinling Mountains, It indicates that the tectonic compression and shortening of the Qinghai-Tibet Plateau caused by the collision and convergence of the Indian plate and the Eurasian plate has not extended to the northern margin of the western Qinling Mountains and the northern part of the western Qinling Mountains at least during the sedimentary filling stage of the basin. However, the sedimentary strata folds and deformations in the salt red bed basin of Zhangxian County are shortened and deformed, and the angle is unconformity in the upper Pleistocene Hanjiagou coarse conglomerate in the salt red bed basin of Zhangzhou County. It is possible to record the transition from extensional boundary to compression-shortened thrust boundary in the northern part of the western Qinling Mountains. Therefore, the northeast margin of the Qinghai-Xizang Plateau became a part of the Qinghai-Tibet Plateau system after the sealing and tectonic inversion of the salt red bed basin in Zhangxian in the Pliocene. This understanding challenges the view of geoscientists that the uplift and tectonic compression of the plateau caused by the collision and convergence of the Indian plate and the Eurasian plate have spread to the northern margin of the western Qinling Mountains as early as the Oligocene epoch.
【作者单位】：天津城建大学地质与测绘学院;甘肃省地质矿产勘查开发局第一地质矿产勘查院;
【基金】：国家自然科学基金项目(41340002,41072149)
【分类号】：P542

【相似文献】