Zircon U-Pb geochronology and Sr-Nd-Hf isotopic compositions of the Yuanzhuding granitoid porphyry within the Shi-Hang Zone, South China: Petrogenesis and implications for Cu-Mo mineralization
Zircon U-Pb geochronology and Sr-Nd-Hf isotopic compositions of the Yuanzhuding granitoid porphyry within the Shi-Hang Zone, South China: Petrogenesis and implications for Cu-Mo mineralization
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DOI：
10.1016/j.lithos.2013.07.003
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发表时间：
2013-09
期刊：
影响因子：
3.5
通讯作者：
Li-feng Zhong;Jie Li;Touping Peng;B. Xia;Liwen Liu
中科院分区：
文献类型：
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作者：
Li-feng Zhong;Jie Li;Touping Peng;B. Xia;Liwen Liu
石行带是华南重要的ne - sw向中生代岩浆带，以εNd(t)值较高、tdm模式年龄较年轻的花岗岩为主。本文采用激光烧蚀电感耦合等离子体质谱法（LA-ICP-MS）对石行带西南部元柱顶斑状花岗岩进行了锆石U-Pb年龄、主微量元素组成和Sr-Nd-Hf同位素测定，并利用这些数据确定了该花岗岩的成因及其与Cu-Mo矿化的关系。锆石U-Pb测年表明，这些花岗岩体的侵位在157.8±1.1 Ma。初始87sr /86Sr比值为0.70941 ~ 0.71398,εNd(t)值为−3.15 ~−2.02，原位锆石εHf(t)值为+ 1.71 ~ + 6.17。地球化学上，它们大多呈高钾钙碱性，并表现出绿质亲和性。它们更有可能位于古太平洋板块向西俯冲的大陆弧环境中。它们的母岩浆主要来自下行板块的上覆沉积物，并在~ 790℃的温度下与岩石圈地幔楔相互作用。岩浆演化过程中的高氧逸度对元珠顶铜钼矿化发育起了至关重要的作用。元竹顶矿床的发现表明，郴州-怀济断裂带是斑岩型铜钼矿最有可能的找矿远景区。
The Shi-Hang Zone is an important NE–SW-trending Mesozoic magmatic belt in South China, which is dominated by granites with relatively high εNd(t) values and young TDMmodel ages. Here, we present laser ablation inductively coupled plasma mass spectrometry (LA–ICP-MS) zircon U–Pb ages, major and trace element compositions, and Sr–Nd–Hf isotope data for the Yuanzhuding porphyritic granitoids within the southwestern Shi-Hang Zone, and use these data to determine the origin of this granitoid and its relationship with Cu–Mo mineralization. Zircon U–Pb dating indicates that these granitoids were emplaced at 157.8 ± 1.1 Ma. They have initial87Sr/86Sr ratios of 0.70941–0.71398, εNd(t) values of − 3.15 to − 2.02, and in situ zircon εHf(t) values of + 1.71 to + 6.17. Geochemically, most of them are high-K calc-alkaline and show an adakitic affinity. They are more likely emplaced in a continental arc setting related to westward subduction of the paleo-Pacific plate. Their parental magma originated chiefly from the overlying sediments of the downgoing slab, and subsequently interacted with the lithospheric mantle wedge at the temperatures of ~ 790 °C. High oxygen fugacity during magmatic evolution played a crucial role in the development of Cu–Mo mineralization within the Yuanzhuding. The discovery of the Yuanzhuding deposit implies that the Chenzhou–Huaiji fault belt is most likely prospective for mineral exploration for porphyry Cu–Mo deposits.