Jurassic-Neogene conglomerate characteristics in Kuqa Depression and their response to tectonic uplifting of Tianshan Mountains

Gao Zhiyong; Zhu Rukai; Feng Jiarui; Li Xiaopei; Zhao Xuesong; Guo Meili

doi:10.11743/ogg20150402

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Jurassic-Neogene conglomerate characteristics in Kuqa Depression and their response to tectonic uplifting of Tianshan Mountains
Vol. 36, Issue 4, Pages: 534-544(2015)
Online First：08 August 2015，

Published：2015
DOI： 10.11743/ogg20150402
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DOI：

Gao Zhiyong, Zhu Rukai, Feng Jiarui, et al. Jurassic-Neogene conglomerate characteristics in Kuqa Depression and their response to tectonic uplifting of Tianshan Mountains[J]. 2015, 36(4): 534-544. DOI： 10.11743/ogg20150402.

摘要

通过对库车坳陷北部野外露头侏罗系-新近系多套砾岩中砾石成分、砾石扁度、球度、砾径及沉积相类型等的分析，半定量评价了南天山山前砾石的沉积搬运距离。研究认为，侏罗系-新近系砾石搬运距离表现为由远及近的规律。剖面点处下侏罗统阿合组-阳霞组砾石搬运距离最远，计算出其搬运距离可达110～130 km；上侏罗统喀拉扎组砾石的搬运距离约为40 km；下白垩统亚格列木组-巴什基奇克组砾石搬运距离较近，约为20～45 km。古近系砾石沉积搬运距离约为20～50 km，新近系吉迪克组砾石的搬运距离最短，在20 km左右。结合前人磷灰石裂变径迹测年数据及研究成果，认为中、新生代天山存在晚三叠世—早侏罗世、晚侏罗世—早白垩世、晚白垩世—始新世及中新世以来4个隆升阶段，隆升范围两小两大。由砾石成分、砾态特征、砾径及砾石搬运距离反映的沉积物源区迁移等变化规律表明，砾岩沉积演化对天山4个阶段隆升的构造运动强烈程度具明显的响应。

Abstract

Samples from multiple sets of the Jurassic-Neogene conglomerate outcrops in Kuqa depression were collected and analyzed for the composition

flatness

sphericity

and size of gravel

and the sedimentary facies that had made everything happened

and for a semi-quantitative study of transportation distance of gravel in front of southern Tianshan Mountain.The results show a far-to-near pattern of gravel transport distance for the Jurassic-Neogene conglomerate.Gravels in the Lower Jurassic Ahe-Yangxia Formations migrated the farthest to 110-130 km

and those from the Neogene Jidike Formation moved the shortest at only 20 km.Between them

the gravels of the Upper Jurassic Kelaza Formation moved about 40 km

that of the Lower Cretaceous Yageliebu-Bashijiqike Formations ran at a distance range between 20 and 45 km and that in the Palaeogene conglomerate transported from 20 to 50 km.Combined with the previous apatite fission track data

the new results indicate that the uplift of the Tianshan Mountains can be divided into 4 stages(two of them were major unplifting and two of them were minor ones):the Triassic-Early Jurassic

Late Jurassic-Early Cretaceous

Late Cretaceous-Eocene

and Miocene-present.The composition

shape and size of the gravels as well as migration of provenance reflected by the gravel transport distance show that the sedimentary evolution of the conglomerate responded strongly to the 4 stages of uplifting process.