矿床地质2023，Vol.42Issue(6)：1229-1246,18.DOI:10.16111/j.0258-7106.2023.06.009
海南岛抱伦金矿床双峰式侵入杂岩地球化学特征及对金成矿作用的启示
Geochemical characteristics of bimodal intrusive complex in Baolun gold deposit,Hainan island and its implications for regional gold mineralization
摘要
Abstract
The Baolun gold deposit in SW Hainan formed in the outer contact zone of the Jianfeng intrusive complex and is closely associated with diabase dyke in space,which contains important information about the magmatic-tectonic-metallogenic evolution system of the gold deposit.An integrated study of Petrology,zircon U-Pb geo-chronology,elemental and Sm-Nd isotope geochemistry was carried on the Jianfeng granite and diabase.The Jian-feng granite and diabase intrusions comprise a bimodal intrusive complex,and the granite intrusion was dated at(234.9±2.8)Ma by LA-ICP-MS method of zircon U-Pb.The diabase is sub-alkaline basaltic in composition,its REE pattern is generally right-inclined with weakly LREE enrichment.It is relatively enriched in highly incom-patible elements of Th,Nb and Ta,and shows no depletion in HFSE of Nb,Ta and Ti.Along with its εNd(t)value of 4.11,it is suggestive of geochemical characteristics of enriched mid-ocean ridge basalt(E-MORB)for the dia-base.The Jianfeng granite is high-K calc-alkaline with an affinity of aluminous A-type granite.Its REE pattern is highly right-inclined and its multi-elements spider pattern displays enrichment in K,Rb,Th,Ce,Y and Yb and de-pletion in Sr,Ba,Nb,Ta,P and Ti.Its εNd(t)values varied between-7.61～-7.80,indicative of recycled crust deri-vation.It is revealed that the Baolun diabase was derived from decompression melting of metasomatic mantle,whereas the Jianfeng granite was originated from the partial melting of the Middle Proterozoic argillaceous and greywacke crust under low pressure and high temperature.The bimodal intrusive magmatism and gold mineraliza-tion were formed in a tectonic setting of post-orogenic extensional-thinning.The bimodal magmatism provided both the crust-and mantle-derived ore-forming materials and migration carriers.The crust-and mantle-derived ore-bearing magmatic hydrothermal fluids are thought to have ascended along the Baisha fault.During this migra-tion process,the ore-forming materials were continuously extracted from the country rocks,resulting in the ore-forming fluid developed into a metamorphic affinity,and finally precipitated in the extensional zone of NNW-trending fault fractures.The key factors dominating the gold mineralization is depressurization,which is attribut-ed to the post-orogenic extensional-thinning tectonic environment.It is suggested the regional traction structures were the ore-bearing hydrothermal transport channels and the main metallogenic locations,which are indicative of main prospecting direction of the deep mineralization in the region.关键词
双峰式侵入杂岩/E-MORB/铝质A型花岗岩/造山后伸展-减薄/抱伦金矿Key words
bimodal intrusive complex/E-MORB/aluminum A-type granite/post orogenic extension-thin-ning/Baolun gold deposit分类
天文与地球科学引用本文复制引用
林弟,宛胜,胡在龙,吕常艳,单强,梁晓,魏昌欣,袁勤敏,高鹏..海南岛抱伦金矿床双峰式侵入杂岩地球化学特征及对金成矿作用的启示[J].矿床地质,2023,42(6):1229-1246,18.基金项目
本文得到海南省海洋地质资源与环境重点实验室开放课题(编号:HNHYDZZYHJKF014)、海南省自然科学基金(编号:421RC1109)和中国地质调查局项目(编号:1212011220710)联合资助 （编号:HNHYDZZYHJKF014）
