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首页> 外文期刊>Journal of Asian earth sciences >Numerical modeling of failed rifts in the northern South China Sea margin: Implications for continental rifting and breakup
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Numerical modeling of failed rifts in the northern South China Sea margin: Implications for continental rifting and breakup

机译：南海边缘失败裂谷的数值模型：对大陆河流和分手的影响

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Failed rifts record important information of continental extension and breakup process in the northern South China Sea (SCS) margin. The Tainan Southern Depression and the Baiyun Sag to the east are characterized with lower-crust high-velocity anomalies (LCHVA), and intracrust detachment faults, whereas the Xisha Trough to the west develops on a larger scale with crust-cutting normal faults and absence of LCHVA. These contrasts indicate different rifting processes between the northeastern and northwestern SCS. 2D numerical modeling is performed to understand the formation mechanism of these failed rifts. Two types of mechanisms are proposed: I) syn-rift competitive type and II) rift migration type with a half extension rate of 2 cm/yr and 1.5 cm/yr, respectively. In type I, two rifts develop initially on the shoulders of the weak zone, but they compete with each other during extension. One rift becomes dominant to furnish the final breakup, whereas the other one is abandoned. The crust structure of this type fits the observations in the Baiyun Sag and the Tainan Southern Depression. However, in type II, only one rift develops at the beginning. The initial rifting center will migrate and the final continental breakup will occur at a place far from the initial rifting location. In this type, normal faults cut through whole crust and wide extensional margins will form, such as observed in the Xisha Trough. Our results suggest that the depth-dependent extension of the SCS is strongly heterogeneous, resulting primarily from varying extensional rates.
机译：Rifts失败记录了南海北部大陆延期和分手过程的重要信息。东南坳陷和东部的白云凹陷具有较低地壳的高速异常（LCHVA）和肠内脱离断层的特征，而西沙槽向西部的巨型槽开发出大规模的地壳 - 切割正常断层和缺席Lchva。这些对比表示东北和西北部SCS之间的不同河流过程。执行2D数值建模以了解这些失败的裂缝的形成机制。提出了两种类型的机制：i）同步竞争型型和II）分别为2cm / Yr和1.5cm / yr的半延伸速率的裂缝迁移型。在I型中，两个裂缝最初在弱区的肩上发育，但它们在延伸期间彼此竞争。一个裂谷使得提供最终分手的占主导地位，而另一个被遗弃。这种类型的地壳结构适合白云凹陷和台南南部萧条的观察。但是，在II型中，只有一个裂谷在开始时发展。初始渔平中心将迁移，最终的大陆分手将发生在远离初始渔平位置的地方。在这种类型中，通过整个地壳和宽延伸边距切割的正常故障，如在西沙槽中观察到。我们的结果表明，SC的深度依赖性延伸强烈异质，主要来自不同的延伸率。

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