Abstract There are many Miocene collision- and subduction-related porphyry Cu deposits in the Eastern Tethyan orogenic belt. However, the petrogenesis of the ore-related magmas and the mechanism of metal enrichment remain controversial. Here, we present a geochemical study and comparison of the major Miocene ore-related porphyries and coeval ore-barren magmatic rocks in the Urumieh-Dokhtar magmatic arc in Iran and the Chagai belt in Pakistan, and the Eastern Gangdese belt of the Himalaya. The results show that ore-related porphyries are characterized by relatively depleted mean Sr isotopic compositions (0.704217–0.706859 in the Urumieh-Dokhtar magmatic arc; 0.705052–0.706588 in the Eastern Gangdese belt; 0.705252–0.706708 in the Chagai belt), but higher maximum Sr/Y ratios (40–149 in Urumieh-Dokhtar; 79–178 in Eastern Gangdese; 52–178 in Chagai). In contrast, the coeval ore-barren magmatic rocks yield relatively enriched, mean Sr isotopic compositions (0.704722–0.707653 in Urumieh-Dokhtar; 0.704701–0.707802 in Eastern Gangdese; 0.705982–0.707856 in Chagai), but lower maximum Sr/Y (2–88 in Urumieh-Dokhtar; 61–136 in Eastern Gangdese; and 19–35 in Chagai). A deep crustal hot zone model provides a robust explanation of these data. Melts derived from a deeper melt source in juvenile mafic lower crust, where mantle-derived materials are common, have a greater potential to yield a higher tonnage of metallic Cu, such as the Sar-Cheshmeh deposit in Iran, which is derived from a deep melt zone, and characterized by a low radioactive mean Sr isotopic value of 0.704851, but a huge tonnage of metallic Cu of 7.2 Mt and a high maximum Sr/Y value of 117 (representative of a deeper depth of the melt zone), whereas the Dalli deposit in Iran derived from a relatively shallow melt zone has a more radioactive mean Sr isotopic value of 0.706859, but a smaller amount of metallic Cu of 0.04 Mt and a lower maximum Sr/Y ratio of 40. Conversely, re-melting the contact between newly-formed and pre-existing crust where mantle-derived materials are absent will produce ore-barren rocks. Additionally, the ore-barren rocks with low Sr/Y ratios (

中文翻译：

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东特提斯造山带中新世斑岩铜矿床：利用 Sr、O 同位素和 Sr/Y 比值预测与矿石相关和贫矿岩浆的来源

摘要 东特提斯造山带中存在着许多与中新世碰撞和俯冲有关的斑岩铜矿床。然而，与矿石有关的岩浆的成因和金属富集机制仍存在争议。在这里，我们对伊朗 Urumieh-Dokhtar 岩浆弧和巴基斯坦 Chagai 带以及喜马拉雅山东部冈底斯带中主要中新世矿石相关斑岩和同期贫矿岩浆岩进行了地球化学研究和比较。结果表明，与矿石有关的斑岩的特征是平均 Sr 同位素组成相对贫化（乌鲁米耶-多赫塔尔岩浆弧为 0.704217-0.706859；东冈底斯带为 0.705052-0.706588；0.705252-0.70 最高值，在察六岩带较高，最高为 0.70） Sr/Y 比率（Urumieh-Dokhtar 为 40-149；Gangdese 东部为 79-178；Chagai 为 52-178）。相比之下，同时期贫矿岩浆岩产生相对富集的平均 Sr 同位素组成（乌鲁米耶-多赫塔尔为 0.704722-0.707653；冈底斯东部为 0.704701-0.707802；0.705982-0.707856），但 Sr 最大值在 2 88 个在乌鲁米耶-多赫塔尔；61-136 个在东冈底斯；19-35 个在察盖）。深部地壳热区模型为这些数据提供了有力的解释。来自年轻基性下地壳中较深熔体源的熔体，其中地幔衍生材料很常见，有更大的潜力产生更高吨位的金属铜，例如伊朗的 Sar-Cheshmeh 矿床，它来自于一个深部熔体区，其特点是放射性平均 Sr 同位素值为 0.704851，但金属铜的吨位巨大，为 7。2 Mt 和 117 的最高 Sr/Y 值（代表更深的熔体区深度），而源自相对较浅熔体区的伊朗 Dalli 矿床具有更高的放射性平均 Sr 同位素值 0.706859，但0.04 Mt 的少量金属 Cu 和 40 的较低最大 Sr/Y 比率。相反，重新熔化新形成的和不存在地幔衍生材料的预先存在的地壳之间的接触将产生贫矿岩石。此外，具有低 Sr/Y 比率的贫矿岩石 ( 重新熔化新形成的地壳和没有地幔衍生材料的现有地壳之间的接触将产生贫矿岩石。此外，具有低 Sr/Y 比率的贫矿岩石 ( 重新熔化新形成的地壳和没有地幔衍生材料的现有地壳之间的接触将产生贫矿岩石。此外，具有低 Sr/Y 比率的贫矿岩石 (