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Underthrusting of the Tarim Lithosphere Beneath the Western Kunlun Range, Insights From Seismic Profiling Evidence
Tectonics ( IF 3.3 ) Pub Date : 2021-02-02 , DOI: 10.1029/2019tc005932
Shengli Wang 1 , Yan Chen 2 , Julien Charreau 3 , Yongxiang Li 1 , Zhuxin Chen 4 , Guangyou Zhu 4 , Huaizhi Xu 1 , Chao Li 1 , Liangshu Wang 1
Affiliation  

Uplift of the western Kunlun range results from the Indian indentation into Eurasia and induced underthrusting of the Tarim lithosphere. This underthrusting keeps pace with migration of the western Kunlun foreland basin. The basin‐scale sequences provide a decipherable record of the migration. To quantify the underthrusting, we analyzed a ∼323.2‐km‐long seismic profile crossing the middle segment of the western Kunlun foreland. We traced seismic reflectors to investigate the architecture of the foreland sequences and assigned ages of reflectors by correlating them with the dated outcropping sections. The foreland sequences consist of four layers. The lowermost Layer 1 starts to lap on the preforeland unit at ∼40 Ma, indicating that the Cenozoic western Kunlun initiated slightly prior to ∼40 Ma. Layer 2 shows a large sharp step northward to exceed the forebulge at ∼25 Ma, suggesting that the modern geomorphology of the Tarim Basin took shape. The southwestern boundary of Layer 4 migrates northeastwards by a fold row relative to that of Layer 3. The gradual retreat of reflector terminations from ∼40 to ∼30 Ma suggests that the Tarim lithosphere is viscoelastic. The linear fitting of the forelandward envelop of reflector termination sites since ∼30 Ma indicates that the Tarim lithosphere underthrusted at an average rate of ∼8.18 mm/yr. This rate comprises the shortening rate of ∼3.8–5.7 mm/yr and the western Kunlun latitudinal propagation rate of ∼4.4–2.5 mm/yr. The abrupt increase in sedimentation rate since ∼11 Ma suggests that western Kunlun had reached its current elevation.

中文翻译:

昆仑山脉西部塔里木岩石圈的逆冲作用,地震剖面证据的启示

昆仑山脉西部的隆起起因于印度向欧亚大陆的凹陷,并引起了塔里木岩石圈的逆冲作用。这种逆冲作用与西部昆仑前陆盆地的迁移保持同步。流域尺度的序列提供了可解释的迁移记录。为了量化逆冲推力,我们分析了跨越昆仑前陆中段的约323.2公里长的地震剖面。我们追踪了地震反射器,以通过与过时的露头剖面相关联来研究前陆序列的结构和反射器的年龄。前陆序列由四层组成。最下层的第1层在〜40 Ma时开始重叠在前陆单元上,这表明新生代西昆仑在〜40 Ma之前就开始了。第2层在向北超过25 Ma时出现了一个较大的陡峭台阶,超过了前隆,表明塔里木盆地的现代地貌已初具规模。第4层的西南边界相对于第3层向东北移动了几倍。反射器终端的逐渐退缩(从40 Ma到30 Ma)表明塔里木岩石圈是粘弹性的。自约30 Ma以来,反射器终止点前向包络的线性拟合表明,塔里木岩石圈的平均推力约为8.18 mm / yr。该速率包括〜3.8-5.7 mm / yr的缩短率和〜4.4-2.5 mm / yr的西昆仑纬度扩展率。自〜11 Ma以来沉积速率的突然增加表明昆仑西部地区已经达到了目前的高度。这表明塔里木盆地的现代地貌已初具规模。第4层的西南边界相对于第3层向东北移动了几倍。反射器终端的逐渐退缩(从40 Ma到30 Ma)表明塔里木岩石圈是粘弹性的。自约30 Ma以来,反射器终止点前向包络的线性拟合表明,塔里木岩石圈的平均推力约为8.18 mm / yr。该速率包括〜3.8-5.7 mm / yr的缩短率和〜4.4-2.5 mm / yr的西昆仑纬度扩展率。自〜11 Ma以来沉积速率的突然增加表明昆仑西部地区已经达到了目前的高度。这表明塔里木盆地的现代地貌已初具规模。第4层的西南边界相对于第3层向东北移动了几倍。反射器终端的逐渐退缩(从40 Ma到30 Ma)表明塔里木岩石圈是粘弹性的。自约30 Ma以来,反射器终止点前向包络的线性拟合表明,塔里木岩石圈的平均推力约为8.18 mm / yr。该速率包括〜3.8-5.7 mm / yr的缩短率和〜4.4-2.5 mm / yr的西昆仑纬度扩展率。自〜11 Ma以来沉积速率的突然增加表明昆仑西部地区已经达到了目前的高度。反射器终端从约40 Ma到约30 Ma逐渐退缩,表明塔里木岩石圈是粘弹性的。自约30 Ma以来,反射器终止点前向包络的线性拟合表明,塔里木岩石圈的平均推力约为8.18 mm / yr。该速率包括〜3.8-5.7 mm / yr的缩短率和〜4.4-2.5 mm / yr的西昆仑纬度扩展率。自〜11 Ma以来沉积速率的突然增加表明昆仑西部地区已经达到了目前的高度。反射器终端从约40 Ma到约30 Ma逐渐退缩,表明塔里木岩石圈是粘弹性的。自约30 Ma以来,反射器终止点前向包络的线性拟合表明,塔里木岩石圈的平均推力约为8.18 mm / yr。该速率包括〜3.8-5.7 mm / yr的缩短率和〜4.4-2.5 mm / yr的西昆仑纬度扩展率。自约11 Ma以来沉积速度的突然增加表明昆仑西部地区已经达到了目前的海拔高度。该速率包括〜3.8-5.7 mm / yr的缩短率和〜4.4-2.5 mm / yr的西昆仑纬度扩展率。自〜11 Ma以来沉积速率的突然增加表明昆仑西部地区已经达到了目前的高度。该速率包括〜3.8-5.7 mm / yr的缩短率和〜4.4-2.5 mm / yr的西昆仑纬度扩展率。自〜11 Ma以来沉积速率的突然增加表明昆仑西部地区已经达到了目前的高度。
更新日期:2021-02-24
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