Extensional rift systems provide important pathways for the release of large amounts of deeply-sourced CO₂ into the atmosphere. Continental rifting zones (e.g., East African rift) are thus invoked to be important for understanding the links between CO₂ outgassing and global climate change associated with continental breakup. However, deeply-sourced CO₂ emissions from extensional rift systems in continental collision zones remain poorly understood. Here, we focus on hydrothermal CO₂ emissions from the southern segment of the Yadong-Gulu rift (YGR), the largest extensional rift in southern Tibetan Plateau, aiming at delineating rift-related CO₂ emissions from the India-Asia continental collision zone. In-situ measurements of diffuse soil CO₂ emissions indicate that average soil CO₂ fluxes from the Kangbu, Mengzha, and Chaduo hydrothermal fields are 40, 700, and 255 g m⁻² d⁻¹, respectively. Combined with average soil CO₂ fluxes (20–437 g m⁻² d⁻¹) from central and northern YGR, we speculate a relatively steady-state CO₂ degassing pattern for the entire rift. The magnitude of soil CO₂ fluxes of the YGR is higher than that of representative areas of the East African rift system. Evidence from ³He/⁴He reveals a pure crustal origin for CO₂-bearing fluids in southern YGR, while the involvement of mantle CO₂ is recognized in the central and northern rift segments. We suggest that metamorphic decarbonation of crustal rocks at variable depths is the primary cause for CO₂ origin in southern YGR, which differs from the magma‑carbonate interaction model of central and northern YGR. Ternary mixing calculation based on He-CO₂ systematics of hydrothermal gases indicates dominant contributions from carbonate rocks to total carbon inventory, with mantle CO₂ contributions absent in southern YGR but discernible in northern YGR. The characteristic high proportions of crustal CO₂ (>90%) distinguish the YGR from extensional rifts fed primarily by mantle CO₂ in continental rifting zones. Our results reveal a crustal-scale carbon cycle in accretionary wedge of the India-Asia continental collision zone, together with magmatic front setting of the central and northern YGR, outlining a transect of the rift-related CO₂ emissions across continental collision zones. This would contribute to better understanding the role of continental assembly in deeply-sourced CO₂ emissions and global carbon budget.

张性裂谷系统为大量深源CO ₂释放到大气中提供了重要途径。因此，大陆裂谷带（例如，东非裂谷）被认为对于理解 CO ₂释气与与大陆分裂相关的全球气候变化之间的联系很重要。然而，大陆碰撞区伸展裂谷系统的深层CO ₂排放仍然知之甚少。在这里，我们重点关注青藏高原南部最大的张性裂谷亚东-古鲁裂谷（YGR）南段的热液 CO ₂排放，旨在描绘与裂谷相关的 CO ₂来自印度-亚洲大陆碰撞区的排放。扩散土壤CO ₂排放的原位测量表明，来自康布、蒙扎和乍多热液田的平均土壤CO ₂通量分别为40、700和255 g m ^-2 d ^-1。结合来自 YGR 中部和北部的平均土壤 CO ₂通量（20-437 g m ^-2 d ^-1），我们推测整个裂谷的CO ₂脱气模式相对稳定。YGR的土壤CO ₂通量的大小高于东非裂谷系统的代表性区域。来自³ He/ ^{4 的}证据他揭示了YGR南部含CO ₂流体的纯地壳起源，而在中部和北部裂谷段发现地幔CO ₂的参与。我们认为不同深度地壳岩石的变质脱碳作用是南黄河带CO ₂成因的主要原因，这与黄河带中北部岩浆-碳酸盐相互作用模型不同。基于热液气体的He-CO ₂系统学的三元混合计算表明碳酸盐岩对总碳库的贡献占主导地位，在 YGR 南部没有地幔 CO ₂贡献，但在 YGR 北部可辨别。地壳CO ₂的特征性高比例(>90%) 将 YGR 与大陆裂谷带中主要由地幔 CO ₂供给的张性裂谷区分开来。我们的研究结果揭示了印度-亚洲大陆碰撞区增生楔中的地壳尺度碳循环，以及 YGR 中部和北部的岩浆锋设置，勾勒出大陆碰撞区与裂谷相关的 CO ₂排放的横断面。这将有助于更好地了解大陆组装在深源 CO ₂排放和全球碳预算中的作用。