Understanding how the Miocene N–S-trending rifts on the southern Tibetan Plateau formed is crucial for understanding the evolution of the plateau. Most competing models suggest that all the rifts developed uniformly, but there are differences in magmatism among them. We conducted ambient noise tomography based on a broadband seismic array deployed across the rifts. A mid-crustal low-Vs layer extends laterally beneath the Tangra Yum Co Rift and the Pumqu-Xianza Rift, implying that E‒W stretching of the ductile middle crust segmented the brittle upper crust, causing rifting and subsequent magmatism. In contrast, the Yadong-Gulu Rift, which experienced prerifting magmatism, is characterized by an isolated low-Vs anomaly extending subvertically from the surface to the middle crust, indicating that the crust experienced magmatic intrusion and local disruption, which promoted the later formation of a large rift. The results suggest that the various rifts might have distinct formation modes.

中文翻译：

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藏南南北走向裂谷的不同形成模式：环境噪声层析成像的启示

了解青藏高原南部中新世南北走向的裂谷是如何形成的对于了解青藏高原的演化至关重要。大多数竞争模型表明所有裂谷的发育都是一致的，但它们之间的岩浆作用存在差异。我们基于部署在裂谷上的宽带地震阵列进行了环境噪声断层扫描。中地壳低Vs层在Tangra Yum Co裂谷和Pumqu-Xianza裂谷下方横向延伸，这意味着韧性中地壳的东西向拉伸分割了脆性上地壳，导致裂谷和随后的岩浆活动。相比之下，经历了裂前岩浆作用的亚东—古鲁裂谷，其特征是孤立的低Vs异常从地表向中地壳垂直延伸，表明地壳经历了岩浆侵入和局部破碎，促进了后期地壳的形成。一个大裂痕。结果表明，各种裂谷可能具有不同的形成模式。