Early Cretaceous high-Mg adakites associated with Cu-Au mineralization in the Cebu Island, Central Philippines: Implication for partial melting of the paleo-Pacific Plate
Early Cretaceous high-Mg adakites associated with Cu-Au mineralization in the Cebu Island, Central Philippines: Implication for partial melting of the paleo-Pacific Plate
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菲律宾中部宿雾岛早白垩世高镁埃达克岩与铜金矿化有关：对古太平洋板块部分熔融的影响
DOI：
10.1016/j.oregeorev.2017.05.006
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发表时间：
2017
影响因子：
3.3
通讯作者：
Sun Weidong
中科院分区：
文献类型：
--
作者：
Deng Jianghong;Yang Xiaoyong;Qi Huasheng;Zhang Zhao-Feng;Mastoi Abdul Shakoor;Sun Weidong
菲律宾中部宿雾岛存在早白垩世弧火山岩、闪长岩侵入体和相关的大型斑岩矿床。本文研究了早白垩世弧火山岩广泛分布的甘西地区与铜金矿化有关的闪长斑岩。锆石 U-Pb 年龄表明，闪长岩形成于大约 1997 年。 110Ma，接近著名的阿特拉斯斑岩铜金矿床中卢托潘闪长岩的形成年龄（109-101Ma），比该地区弧火山岩的形成年龄（126-118Ma）更年轻。坎西闪长岩和卢托潘闪长岩均为钙碱性高镁埃达克岩，具有高 Sr/Y 比。它们的主要元素在哈克图中定义了相似的变化趋势，表明它们可能是由统一来源产生的，但经历了不同程度的部分熔融或分步结晶。坎西闪长岩具有富轻稀土、贫重稀土的特点，无Eu负异常，富Pb、Sr、Zr、Hf，贫Nb、Ta、Ti。它们可能是由于俯冲洋壳部分熔融，随后发生一定程度的地幔相互作用和地壳污染而产生的。关西闪长岩的高度贫化的Sr-Nd-Pb-Hf同位素与奄美高原玄武岩和英云闪长岩接近，表明源区以太平洋型MORB为主。与铜金矿化有关的坎西闪长岩具有大于ΔFMQ+2的高氧逸度，表明该地区具有较好的斑岩铜金矿化潜力。最后，在我们的构造模型中，宿务岛岛弧火山岩和埃达克岩的连续生成是早白垩世古太平洋板块向原菲律宾海板块（PSP）俯冲和回滚的响应。
Early Cretaceous arc volcanic rocks, diorite intrusions and an associated large porphyry deposit occur in the Cebu Island, Central Philippines. In this paper, we studied the diorite porphyries associated with Cu-Au mineralization in the Kansi region, where Early Cretaceous arc volcanic rocks are widely distributed. Zircon U-Pb age reveals that the diorites were formed at ca. 110 Ma, close to the formation age of Lutopan diorites in the famous Atlas porphyry Cu-Au deposit (109–101 Ma), and younger than those of the arc volcanics in this region (126–118 Ma). The Kansi diorites and Lutopan diorites are both calc-alkaline high-Mg adakites with high Sr/Y ratios. Their major elements define similar variation trends in Harker diagrams, suggesting that they were probably generated from a uniform source but experienced different degree of partial melting or fractional crystallization. The Kansi diorites are characterized by LREE enrichment, HREE depletion, no Eu negative anomaly, with enrichment of Pb, Sr, Zr and Hf and depletion of Nb, Ta, and Ti. They are probably generated by the partial melting of subducted oceanic crust, followed by a certain degree of mantle interaction and crustal contamination. The highly depleted Sr-Nd-Pb-Hf isotopes of the Kansi diorites are close to the Amami Plateau basalt and tonalite, indicating the dominance of a Pacific-type MORB in the source. The Cu-Au mineralization-related Kansi diorites are characterized by high oxygen fugacities more than ΔFMQ +2, indicating quite a good potential for porphyry Cu-Au mineralization in the region. Finally, in our tectonic model, the successive generation of arc volcanic rocks and adakites in the Cebu Island are responses to the subduction and rollback of the paleo-Pacific Plate to the proto-Philippine Sea Plate (PSP) in the Early Cretaceous.