Many of the world's rifts and rifted margins have developed within former orogens. The South China Sea (SCS) formed during Cenozoic rifting by utilizing pre-existing orogenic structures, like thrust faults, thickened crust, and corresponding thermal weaknesses. The mechanisms explaining how inherited structures influence the spatiotemporal evolution of a rift remain a topic of on-going research. Here, we explore the impact of orogenic inheritance on rift evolution through a numerical forward model that reproduces geodynamic and landscape evolution processes. By imposing time-dependent phases of shortening and extension, we model rifted margin formation that is consistent with the available geological and geophysical observations of the SCS. Our numerical models allow us to identify thrust faults that are reactivated as normal faults during extensional phases. Not all pre-existing thrust faults, however, undergo full reactivation, as their behavior is influenced by variations in lithospheric strength and the pre-existing structural discontinuities. We further show that inherited orogenic structures compete with each other during extensional reactivation and ultimately govern the location of continental breakup. Our results provide valuable insights into the broader implications of inherited orogenic structures and how they affect subsequent rift system evolution.

中文翻译：

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从造山运动到裂谷：遗传结构在南海形成过程中的作用


世界上许多裂谷和裂谷边缘是在以前的造山带中形成的。南海 （SCS） 是在新生代裂谷期间通过利用预先存在的造山结构（如逆冲断层、增厚的地壳和相应的热弱点）形成的。解释遗传结构如何影响裂隙时空演变的机制仍然是一个正在进行的研究主题。在这里，我们通过再现地球动力学和景观演化过程的数值正向模型来探索造山遗传对裂谷演化的影响。通过施加与时间相关的缩短和延伸阶段，我们模拟了与 SCS 可用的地质和地球物理观测一致的裂谷边缘形成。我们的数值模型使我们能够识别在伸展阶段被重新激活为正常断层的逆冲断层。然而，并非所有预先存在的逆冲断层都会完全重新激活，因为它们的行为会受到岩石圈强度变化和预先存在的结构不连续性的影响。我们进一步表明，遗传的造山结构在伸展再激活过程中相互竞争，并最终控制大陆分裂的位置。我们的结果为遗传造山结构的更广泛影响以及它们如何影响随后的裂谷系统进化提供了有价值的见解。