鄂东南地区金井咀金矿早白垩世闪长岩Sr-Nd及锆石Hf同位素研究

李岩; 程春; 苏绍明; 高剑峰; 黄费新; 熊映志; 张岩; 黄华

doi:10.12029/gc20200611002

鄂东南地区金井咀金矿早白垩世闪长岩Sr-Nd及锆石Hf同位素研究

Sr-Nd and zircon Hf isotopic constraints on petrogenesis of the Early Cretaceous diorite in the Jinjingzui gold deposit, southeast Hubei Province

摘要

摘要:
研究目的 金井咀金矿床早白垩世闪长岩的岩石成因及岩浆起源对于讨论成岩成矿关系、完善区域成矿规律等问题具有重要意义。
研究方法 本文对矿区赋矿闪长岩开展了全岩Sr-Nd和锆石Hf同位素分析。
研究结果 金井咀闪长岩具有相对较高的⁸⁷Sr/⁸⁶Sr初始比值（0.7059~0.7062），负的ε_Nd（t）值（-7.93~-7.58）和锆石ε_Hf（t）值（-12.2~-6.5），表明岩浆形成于富集地幔的部分熔融，后经历了演化分异，在岩浆演化过程中可能存在一定程度的陆壳混染。
结论通过与区域上已经发现的矿床对比发现，金井咀矽卡岩型金矿床与鄂东南矿集区矽卡岩型金矿床具有相同的成岩成矿时代和类似的岩石成因及岩浆源区，但是金井咀矿床金矿体主要赋存在闪长岩体内部，这与其他矿床主要赋存在碳酸盐岩地层或岩体内外接触带明显不同。金井咀矿床的发现，对于完善区域成矿规律，指导金矿找矿勘查具有重要的意义。

Abstract:
This paper is the result of geological survey engineering.
Objective The petrogenesis and magmatic origin of the early Cretaceous diorite in Jinjingzui gold deposit are of great significance for the diagenetic and metallogenic relations and perfecting the regional metallogenic regularity.
Methods In this study we report the Sr-Nd and zircon Hf isotopic compositions of diorite in Jinjingzui deposit.
Results The results show that the diorite has relative high initial ⁸⁷Sr/⁸⁶Sr ratio (0.7059-0.7062), negative ε_Nd(t) values (-7.93--7.58) and ε_Hf(t) values (-12.2--6.5), suggesting the magma was derived from partial melting of an enrichment mantle, followed by magma differentiation. There may be continental crust contamination during magmatic evolution.
Conclusions By comparison with reported deposit in cluster, Jinjingzui Au deposit is similar to these Au deposit at Edong cluster in rock- and ore-forming ages, petrogenesis and magma source. However, the gold orebody of Jinjingzui Au deposit mainly lay within the diorite body, which is obviously different from other deposits that lay internal or external contact zone of rocks. The discovery of Jinjingzui deposit is of great significance for perfecting regional metallogenic regularity and gold prospecting and exploration.

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