Late Cenozoic tectonics of the Kepingtage thrust zone: Interactions of the Tien Shan and Tarim Basin, northwest China
Late Cenozoic tectonics of the Kepingtage thrust zone: Interactions of the Tien Shan and Tarim Basin, northwest China
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DOI：
10.1029/1999tc900019
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发表时间：
1999-08
期刊：
影响因子：
4.2
通讯作者：
M. Allen;S. Vincent;Paul J. Wheeler
中科院分区：
文献类型：
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作者：
M. Allen;S. Vincent;Paul J. Wheeler
柯坪塔格冲断带是印度-亚洲碰撞体系中变形活跃的一部分。它位于天山以南，面积为16,000平方公里，由弧形、出露的叠瓦岩组成。总体上向南朝向塔里木盆地内部。逆冲岩席通常使上寒武统至二叠纪台地地层暴露。逆冲断层主要是薄皮的;薄的上寒武统碎屑岩可能是主要的滑脱层位。柯坪塔格冲断带是塔里木盆地新生代唯一的一条以这种方式变形的构造带。它的东、西方向被逆冲带所取代，逆冲带向塔里木盆地内部延伸的距离较短。厚（达10公里）的中生代和新生代碎屑岩序列的存在和变形在这些地区。在塔里木盆地内的柯坪塔格冲断带或邻近的巴楚隆起中不存在这种连续性，因为在确定巴楚隆起边缘的西北-东南向陡峭冲断带上存在幕式活动。这些中新生代地层可能抑制了柯坪塔格逆冲带走向沿着区域利用上寒武统滑脱作用进行薄皮逆冲变形的能力。天山南缘逆冲构造活动的沿着向变化是同构造沉积作用控制逆冲构造带变形样式的一个实例。一个横跨逆冲带的平衡剖面表明缩短了1.28%，相当于1.35公里。这相当于平均滑动速率为1.8 mm yr−1，应变速率为1.4 × 10−16 s−1，假设变形开始于大约20 Ma。活动变形集中在正面逆冲断层（柯坪塔格断层）上，沿着。柯坪塔格冲断带的北方边界由南天山断裂带构成。这个主要的北倾逆冲断层是地震活跃的，已公布的地震震源深度在中地壳水平（14和18公里）。它将不同相和不同古生代变形历史的上石炭统沉积岩并置。推测，它代表了晚古生代逆冲断层的复活，该逆冲断层起源于塔里木地块的台地内部与其北部的深水前陆盆地之间的边界。
The Kepingtage (Kalpin) thrust zone, northwest China, is an actively deforming part of the India‐Asia collision system. It lies south of the Tien Shan, has an area of ∼16,000 km2, and consists of arcuate, emergent imbricates. Overall vergence is toward the interior of the Tarim Basin to the south. Thrust sheets typically expose Upper Cambrian to Permian platformal strata. Thrusting is largely thin‐skinned; thin Upper Cambrian evaporites are likely to be the main decollement horizon. The Kepingtage thrust zone is the only margin of the Tarim Basin to deform in this style in the Cenozoic. It is replaced to the east and west by thrust zones which have propagated shorter distances into the interior of the Tarim Basin. Thick (up to 10 km) Mesozoic and Cenozoic clastic successions are present and deformed in these regions. Such successions are not present in the Kepingtage thrust zone or the adjacent Bachu Uplift within the Tarim Basin, because of episodic activity on steep, northwest‐southeast trending thrusts which define the margins of the Bachu Uplift. These Mesozoic‐Cenozoic strata may have suppressed the ability of regions along strike from the Kepingtage thrust zone to deform by thin‐skinned thrusting utilizing the Upper Cambrian decollement. The along strike variation in active thrusting at the southern margin of the Tien Shan is an example of syntectonic sedimentation controlling thrust belt deformation style. A balanced section across the thrust zone indicates ∼28% shortening, equivalent to ∼35 km. This is equivalent to an average slip rate of ∼1.8 mm yr−1 and a strain rate of ∼4.4 × 10−16 s−1, assuming deformation began at circa 20 Ma. Active deformation is focused along the frontal thrust, the Kepingtage Fault. The northern boundary of the Kepingtage thrust zone is formed by the South Tien Shan Fault. This major, north dipping thrust is seismically active, with published earthquake focal depths at midcrustal levels (14 and 18 km). It juxtaposes upper Carboniferous sedimentary rocks of different facies and different Paleozoic deformation histories. Speculatively, it represents a reactivation of a late Paleozoic thrust, which originated at the boundary between the platformal interior of the Tarim Block and a deeper‐water foreland basin to its north.