| 西秦岭北缘构造带的新生代构造活动——兼论对青藏高原东北缘形成过程的指示意义 |
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| 引用本文： | 王志才,张培震,张广良,李传友,郑德文,袁道阳.西秦岭北缘构造带的新生代构造活动——兼论对青藏高原东北缘形成过程的指示意义[J].地学前缘,2006,13(4):119-135. |
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| 作者姓名： | 王志才 张培震 张广良 李传友 郑德文 袁道阳 |
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| 作者单位： | 中国地震局地质研究所,地震动力学国家重点实验室,北京,100029 |
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| 摘 要： | 西秦岭北缘构造带是青藏高原东北部一条重要的北西西向构造带,它由一组近于平行的断裂组成,中部发育活动的左旋走滑断裂,两侧发育向外扩展的多条逆冲断裂,剖面上呈向北偏心的花状构造。自古近纪中晚期以来西秦岭北缘构造带成为青藏高原早期的北东边界,其新生代构造活动控制了两侧的新生代盆地沉积演化和构造变形。在构造带南侧滩歌盆地自古近纪中晚期堆积了一套厚度较大的砾岩和砂岩地层,但未见新近纪地层;沿西秦岭北缘构造带中部在中新世形成具有剪切拉张性质的武山—漳县盆地,沉积了厚度超过千米的砾岩、砂岩和泥岩序列;在构造带北侧陇西盆地从古近纪中晚期至中新世晚期一直处于前陆盆地发育阶段,沉积了连续的新生代地层序列。在中新世晚期以后,整个构造带遭受挤压变形,逆冲活动强烈,中部的武山—漳县盆地和北侧的陇西盆地相继消亡,新生代地层发生强烈构造变形,位于构造带南侧的滩歌盆地也同时发生轻微缩短变形。第四纪晚期以来西秦岭北缘构造带断裂活动主要表现为左旋走滑运动方式,而逆冲断裂活动则迁移到了北东方向的海原断裂和香山—天景山断裂(又称中卫—同心断裂)等构造带之上,实现了大区域范围内的应变分配。
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| 关 键 词： | 新生代 西秦岭北缘构造带 青藏高原东北部 |
| 文章编号： | 1005-2321（2006）04-0119-17 |
| 收稿时间： | 2005-12-30 |
| 修稿时间： | 2006-04-17 |
Tertiary tectonic activities of the north frontal fault zone of the west Qinling mountains: implications for the growth of the northeastern margin of the Qinghai-Tibetan plateau |
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| WANG Zhi-cai,ZHANG Pei-zhen,ZHANG Guang-liang,LI Chuan-you,ZHENG De-wen,YUAN Dao-yang.Tertiary tectonic activities of the north frontal fault zone of the west Qinling mountains: implications for the growth of the northeastern margin of the Qinghai-Tibetan plateau[J].Earth Science Frontiers,2006,13(4):119-135. |
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| Authors: | WANG Zhi-cai ZHANG Pei-zhen ZHANG Guang-liang LI Chuan-you ZHENG De-wen YUAN Dao-yang |
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| Institution: | Institute of Geology, China Earthquake Administration, National Laboratory of Earthquake Dynamics, Beijing 100029, China |
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| Abstract: | The north frontal fault zone of the west Qinling (NFFWQ) is one of the important NWW-trending fault zones in the northeastern margin of the Tibetan plateau (NEMTP); it consists of a series of nearly parallel faults. Among them is a currently active left lateral strike-slip fault in the middle of a flower-type assemblage of outward-directed thrust faults. Based on fieldwork in Longxi and Wushan regions of east Gansu province, thrust faulting predominated the history of the fault belt in the Cenozoic time, whereas strike-slip movement in the middle of the fault belt probably did not appear until the Miocene. Since the middle-late Paleogene the NFFWQ became the northeastern boundary fault of the early Tibetan plateau, and subsequently it has played a very important role in the process of the tectonic deformation and basin evolution in this region. To the south of the NFFWQ thick layers of violet - brick red conglomerate and sandstone beds were deposited in the Tange basin in the middle-late Paleogene; Neogene strata are not present. Along the middle of the NFFWQ the transtensional Wushan-Zhangxian basin developed in the Miocene, and received more than one thousand meters of conglomerate, sandstone and clay. The Longxi basin developed on the north side of the NFFWQ as a foreland basin from the middle-late Paleogene to the late Miocene.Thick layers of the Cenozoic sequence were deposited nearly continuously. The entire NFFWQ belt has undergone strong compression since the late Miocene. Thrusting has been widespread and deposition in the Wushan and Longxi basins ended successively with the advent of strong deformation. At the same time, the Tange basin on the south side of the NFFWQ suffered minor shortening. Since the late Quaternary strain partitioning across large areas is obvious; left-lateral movement dominates the NFFWQ belt, whereas thrust faulting has shifted to faults far to the northeast, such as the Haiyuan fault and the Xiangshan-Tianjingshan fault. |
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| Keywords: | Tibetan plateau northeastern margin Cenozoic tectonic deformation north frontal fault zone of the west Qinling |
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