Using migrating growth strata to confirm a ∼230-km-long detachment thrust in the southern Tarim Basin
Using migrating growth strata to confirm a ∼230-km-long detachment thrust in the southern Tarim Basin
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DOI：
10.1016/j.jsg.2021.104488
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发表时间：
2021-12-11
影响因子：
3.1
通讯作者：
Yang, Shaomei
中科院分区：
文献类型：
--
作者：
Chen, Hanlin;Zhang, Yuqing;Yang, Shaomei
断层滑动量和断层活化时间是构造定量分析的两个基本要素。目前，这两个参数主要取决于断层相关褶皱的几何形状和断层斜坡上的生长地层。在这项研究中，我们提出了一种新的生长地层类型，直接限制断层滑动量和断层活动的时间在断坪地震反射剖面的解释和相关的数值模拟的基础上，沿沿着的马南构造。地震剖面显示，在马南背斜北翼之外存在一个无根的向斜，其枢纽向北倾斜。数值模拟结果表明，该构造是生长层沿着向北迁移的结果，并伴随着下伏拆离逆冲断层的滑动，在断层面上形成隆起。我们将这种类型的生长层定义为“迁移生长层”。向斜构造枢纽的倾伏方向标志着滑动方向，枢纽在断层面上的突出距离衡量着滑动量，MGS的发生时间代表着下伏拆离逆冲断层活动的时间。对塔里木盆地沿着马南MGS的分析表明，马南构造沿新生代基底拆离作用向北滑动了13-22 km，最终被玛扎塔格带吸收，证实了塔里木盆地南部存在一个类似于230 km的拆离逆冲断层，为和田带与玛扎塔格带的运动学联系提供了重要证据。向斜枢纽的两段式构造样式表明，马南构造经历了与下寒武统和新生代基底构造有关的两期演化。这些结果表明，青藏高原不同深度的地壳运动及其连续活动是青藏高原向欧亚大陆内部传递应变的关键。
The amount of fault slip and timing of fault activation are two fundamental elements of quantitatively structural analysis. Currently, these two parameters are mainly determined by the geometry of fault-related folds and the growth strata over the fault ramp. In this study, we propose a new type of growth strata that directly constrain both the amount of fault slip and the timing of fault activity at the fault flat based on interpretations of seismic reflection profiles and related numerical modeling of the Manan Structure along the southern Tarim Basin. The seismic sections show a rootless synform beyond the north limb of the Manan Anticline with the hinge dipping toward north. Numerical modeling suggests that this synform is a result of northward migration of the growth strata along with the slip of the underlying detachment thrust with a bulge at the fault surface. We define this type of growth strata 'migrating growth strata (MGS)'. The dipping direction of the hinge of the synform marks the slip direction, the projecting distance of the hinge on the fault surface measures the slip amount, and the timing of the MGS represent the timing of the activity of the underlying detachment thrust. Analyses of the Manan MGS along the southern Tarim Basin suggest similar to 13-22 km of northward fault slip passed by the Manan Structure along the basal Cenozoic detachment and was finally absorbed by the Mazatagh Belt, which confirms a similar to 230-km-long detachment thrust along the southern Tarim Basin and provide key evidence to establish a kinematic linkage between the Hotan and Mazatagh Belts. Two-segment style of the hinge of the synform indicates that the Manan Structure has undergone two-stage evolution related to the lower Cambrian and the basal Cenozoic detachments, respectively. These results imply that detachments in difference depths and their sequential activities are key in transmitting strain from the Tibetan Plateau into the Eurasian continental interiors.