The dynamics of continental breakup at convergent margins have been described as the results of back‐arc opening caused by slab rollback or drag force induced by subduction direction reversal. Although the rollback hypothesis has been intensively studied, our understanding of the consequence of subduction direction reversal remains limited. Using thermo‐mechanical modeling based on constraints from the South China Sea (SCS) region, we investigate how subduction direction reversal controls the breakup of convergent margins. The numerical results show that two distinct breakup modes, namely continental interior and edge breakup (“edge” refer to continent above the plate boundary interface), may develop depending on the “maturity” of the convergent margin and the age of the oceanic lithosphere. For a slab age of ~15‐~45 Ma, increasing the duration of subduction promotes the continental interior breakup mode, where a large block of the continental material is separated from the overriding plate. In contrast, the continental edge breakup mode develops when the subduction is a short‐duration event, and in this mode a wide zone of less continuous continental fragments and tearing of the subducted slab occur. These two modes are consistent with the interior (relic late Mesozoic arc) and edge (relic fore‐arc) rifting characteristics in the western and eastern SCS margin, suggesting that variation in the northwest‐directed subduction duration of the Proto‐SCS might be a reason for the differential breakup locus along the strike of the SCS margin. Besides, a two‐segment trench associated with the northwest‐directed subduction is implied in the present‐day SCS region.

中文翻译：

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俯冲方向反转引起的会聚边缘的大陆内部和边缘破裂：适用于南海边缘的数值模拟研究

会聚边缘的大陆破裂动力学被描述为板片回滚引起的弧后张开或俯冲方向反转引起的拖曳力的结果。尽管已经对回滚假说进行了深入研究，但我们对俯冲方向反转的后果的理解仍然有限。使用基于南海 (SCS) 区域约束的热机械模型，我们研究了俯冲方向反转如何控制收敛边缘的破裂。数值结果表明，根据会聚边缘的“成熟度”和海洋岩石圈的年龄，可能会形成两种不同的破碎模式，即大陆内部和边缘破碎（“边缘”是指板块边界界面上方的大陆）。对于~15-~45 Ma 的板坯年龄，增加俯冲持续时间促进大陆内部破裂模式，其中一大块大陆物质与上覆板块分离。相比之下，当俯冲为短期事件时，大陆边缘破裂模式发展，在这种模式下，会出现较宽的大陆碎片和俯冲板块撕裂的较宽区域。这两种模式与南海西部和东部边缘的内部（中生代晚期遗迹弧）和边缘（遗迹前弧）裂谷特征一致，表明原始南海向西北俯冲持续时间的变化可能是沿着 SCS 边缘走向的不同破裂轨迹的原因。此外，在现今的南海地区隐含着一条与西北向俯冲相关的两段海沟。