The genetic link between subduction- and collision-related porphyry Cu deposits (PCD) is still not well understood. The Gangdese porphyry Cu belt (GPCB) in southern Tibet hosts two parallel E–W-oriented metallogenic subbelts, including a southern Jurassic subduction-related and a northern Miocene post-collision PCD subbelt. In this study, we combine new and published whole-rock major and trace element data, Cu isotopic compositions and zircon trace element data of Jurassic magmatic rocks from the GPCB. Combined Sr/Y and La/Yb crustal thickness proxies confirm the south to north geometry of the Jurassic arc-back-arc system across the GPCB. The southern Jurassic magmatic arc rocks have systematically higher whole-rock V/Yb ratios, δ⁶⁵Cu values and zircon Eu/Eu* ratios compared to those of the northern back-arc region. This suggests that Jurassic southern arc magmas had higher oxygen fugacity and H₂O concentration than the contemporaneous northern back-arc magmas, which was controlled by a steep subduction geometry of the Neo-Tethyan oceanic slab. Hydrous and oxidized magmas resulted in Cu enrichment during magma evolution and generation of Jurassic PCD in the southern magmatic arc by inhibiting early sulfide saturation at deep crustal levels. In contrast, the northern back-arc magmas were less oxidized and less hydrous, which triggered early sulfide saturation, resulting in segregation of Cu-bearing sulfides in lower crustal cumulates that provided a favorable metal source for later Miocene PCD in the northern subbelt. Our study indicates that the Jurassic subduction geometry controlled the formation and distribution of Jurassic subduction-related and Miocene post-collision-related PCD in the GPCB.

俯冲和碰撞相关的斑岩铜矿床 (PCD) 之间的成因联系仍不清楚。藏南冈底斯斑岩铜矿带（GPCB）发育两条平行的东西向成矿亚带，包括南部侏罗纪俯冲相关亚带和北部中新世碰撞后PCD亚带。在这项研究中，我们结合了新发表的全岩主量元素和微量元素数据、来自 GPCB 的侏罗纪岩浆岩的铜同位素组成和锆石微量元素数据。综合 Sr/Y 和 La/Yb 地壳厚度代理证实了整个 GPCB 侏罗纪弧-弧后系统的从南到北的几何形状。南部侏罗纪岩浆弧岩石具有系统较高的全岩 V/Yb 比值，δ ⁶⁵与北部弧后区域相比的 Cu 值和锆石 Eu/Eu* 比值。这表明侏罗纪南弧岩浆具有较高的氧逸度和H ₂O 浓度高于同期北部弧后岩浆，这是由新特提斯洋板的陡峭俯冲几何形状控制的。含水和氧化岩浆通过抑制深部地壳早期硫化物饱和，导致岩浆演化过程中铜富集，并在南部岩浆弧形成侏罗纪PCD。相比之下，北部弧后岩浆氧化程度较低，含水量较低，引发了早期硫化物饱和，导致含铜硫化物在下地壳堆积物中偏析，为北部亚带后期中新世PCD提供了有利的金属来源。我们的研究表明，侏罗纪俯冲几何形状控制了GPCB中侏罗纪俯冲相关和中新世碰撞后相关PCD的形成和分布。