帕米尔弧形构造带东北缘晚新生代构造活动的沉积与重矿物变化响应

Late Cenozoic tectonic process in the NE Pamir Salient:Evidences from the sedimentary record and heavy mineral changes

帕米尔弧形构造带东北缘晚新生代沉积特征的研究对于理解帕米尔构造带弧形扩展机制具有重要意义。本文通过对帕米尔弧形构造带东北缘的晚新生代沉积地层的沉积特征对比研究和重矿物采样与组份分析,建立了帕米尔弧形构造带东北缘地区的晚新生代沉积联合柱状对比图和重矿物组份变化曲线。研究结果表明,晚新生代沉积与重矿物变化主要记录了帕米尔弧形构造带东北缘的两期构造活动。第一期构造活动发生在安居安组沉积时期,帕米尔弧形构造带东北缘的和什拉甫剖面、英科1井表现为粗碎屑沉积和对应的不稳定重矿物爆发,而南部的甫沙2井中则并未观察到,这一事件可能反映了喀什-叶城走滑系统在和什拉甫剖面附近的中新世构造启动。第二期构造活动发生在阿图什组沉积期间,帕米尔弧形构造带东北缘全区域出现了一套粗碎屑沉积和对应的不稳定重矿物爆发,反映了帕米尔弧形构造带东北缘在上新世以来大规模向北楔入塔里木盆地内部的构造过程。

The Late Cenozoic sedimentary record in the NE Pamir Salient is significant for understanding the Cenozoic tectonic processes of the Pamir Salient.In this study,we performed the sedimentary and heavy mineral analyses of the Late Cenozoic strata in the NE Pamir Salient.The results mainly indicate two stages of tectonic process in the NE Pamir Salient.The first stage occurred during the deposition of the Anjuan Formation.During this period,coarse-grained sediments were well-developed in the Heshilafu section and Yingke-1 borehole with the corresponding massive emergence of the relatively unstable heavy minerals.While,this event can be only observed in this limited area,and may suggest the Miocene initial onset of the Kashgar-Yecheng Transfer System nearby the Heshilafu section and Yingke-1 borehole.The second stage occurred during the deposition of the Atushi Formation.There were widelyexposed coarse-grained sediments in the NE Pamir Salient with the corresponding massive emergence of the relatively unstable heavy minerals during this period.This event may suggest the large-scale wedging of the NE Pamir Salient into the Tarim Basin since the Pliocene.