河南省西峡县高庄金矿Rb-Sr等时线年龄和H、O、S、Pb同位素特征:北秦岭板内造山成矿作用的识别  

Rb-Sr isochron age and isotopic compositions of H, O, S and Pb of the Gaozhuang gold deposit, Xixia County, Henan Province: Identification of intraplate orogenic metallogenesis in northern Qinling Mountain

作　　者：梁涛 卢仁 杨楠 王莉 温静静 LIANG Tao;LU Ren;YANG Nan;WANG Li;WEN Jingjing(General Institute of Non-ferrous Metals Geologic Exploration,Zhengzhou 450052,Henan,China;Key Laboratory of Deep Ore-prospecting Technology Research for Non-ferrous Metals of Henan Province,Zhengzhou 450052,Henan,China)

机构地区：[1]河南省有色金属地质勘查总院,河南郑州450052 [2]河南省有色金属深部找矿勘查技术研究重点实验室,河南郑州450052

出　　处：《中国地质》2020年第2期406-425,共20页Geology in China

基　　金：国家自然科学基金项目(U1504405);河南省国土资源厅科技攻关项目(2016-08、2014-06)联合资助。

摘　　要：高庄金矿是河南省北秦岭金矿床集中区内的典型矿床之一,为限定它的形成时代,探讨深部成矿动力学过程,揭示深源成矿物质的释放机制和分析深部及区域Au成矿潜力,对高庄金矿开展了矿石Rb-Sr同位素定年和H、O、S、Pb同位素测试。7件矿石样品中黄铁矿和石英的87Rb/86Sr和87Sr/86Sr比值范围分别为0.0709~5.963和0.711139~0.721982,初始87Sr/86Sr比值为0.711025±0.000052,等时线年龄为(129.8±1.4)Ma(MSWD=1.3),与烟镇岩体和高庄花岗细晶岩的年龄几乎一致,说明它们近同时形成于早白垩世约130 Ma。高庄金矿3件石英样品的δ18OV-SMOW值和δDV-SMOW值分别介于11.6‰~12.1‰和-60.9‰^-42.5‰,它们的δ18OH2O值介于2.16‰~2.66‰,表明高庄金矿成矿流体具有混合来源的特征。6件黄铁矿样品的δ34S值介于-2.8‰^-1.6‰,具有塔式分布特征,显示幔源硫特征。7件样品的206Pb/204Pb比值、207Pb/204Pb比值和208Pb/204Pb比值范围分别为17.549~18.278、15.461~15.619和37.593~38.428,它们的μ值、△α值、Δβ值和Δγ值范围依次为9.30~9.51、59.52~75.10、11.44~19.80和30.38~37.99。在206Pb/204Pb-207Pb/204Pb和206Pb/204Pb-208Pb/204Pb图解中,高庄金矿样品点主要位于造山带Pb演化线两侧。在Δβ-Δγ图解中,它们落入上地壳与地幔混合的俯冲带Pb和造山带Pb两个源区域内。高庄金矿的成矿物质来源于上地幔-下地壳,成矿过程中有上地壳物质加入,具有多源区混合的特征。高庄金矿床的形成与北秦岭燕山期板内(陆内)造山过程密切相关,它与埃达克质烟镇岩体及高庄花岗细晶岩同为区域岩石圈拆沉作用的产物。深部含矿流体也因此获得大规模快速释放,在上升过程中联通了浅部不同深度范围的多层成矿源区,在汇聚混合之后上侵到地壳浅部构造有利部位形成高庄金矿,表明高庄金矿深部及烟镇岩体周缘具有大的内生金属成矿潜力。The Gaozhuang gold deposit is one of the important Au deposits in Au polymetallic ore concentration area of northern Qinling Mountain, Henan Province. The Rb-Sr isochron age and H, O, S and Pb isotopes of ores from the Gaozhuang gold deposit were analyzed so as to constrain Au mineralization formation age and discuss the source of ore metals and the controlling factor of deep ore fluids discharge as well as the Au mineralization potential. The87 Rb/86 Sr and87 Sr/86 Sr ratios of pyrite and quartz from 7 ore samples are in the range of 0.0709-5.963 and 0.711139-0.721982, respectively. The initial 87 Sr/86 Sr ratios are in the range of0.711025 ± 0.000052 and the Rb-Sr isochron age is(129.8 ± 1.4)Ma(MSWD=1.3), almost consistent with the age of the Yanzhen granitic intrusive and the Gaozhuang granitic aplite. It is suggested that they were nearly formed at the same time of-130 Ma in early Cretaceous. The δ18 OV-SMOWand δDV-SMOWvalues of 3 quartz samples are 11.6‰-12.1‰ and-60.9‰--42.5‰, respectively. Theirδ18 OH2 Ovalues range from 2.16‰ to 2.66‰, suggesting that ore-forming fluids of the Gaozhuang gold deposit were a mixed source.The δ34 SV-CTDvalues of 6 pyrite samples are from-2.8‰ to-1.6‰ with a tower shape in the δ34 S histogram, which indicates a mantle source. The ratios of206 Pb/204 Pb,207 Pb/204 Pb and208 Pb/204 Pb of 7 samples are 17.549-18.278, 15.461-15.619 and 37.593-38.428,respectively. Their μ, △ α, Δβ and Δγ are 9.30-9.51, 59.52-75.10, 11.44-19.80 and 30.38-37.99. In 206 Pb/204 Pb-207 Pb/204 Pb and206 Pb/204 Pb-208 Pb/204 Pb diagrams, sample points of the Gaozhuang gold deposit are close to the orogenic line. They fall into the crust-mantle subduction zone mixed lead source and the orogenic belt lead source in Δβ-Δγ of Pb isotopic diagram. It is suggested that metallogenic materials of the Gaozhuang gold deposit were derived from the lower crust and the upper mantle, with the addition of the upper crust materials in the ore-forming process. The formation of the Gaozh

关 键 词：高庄金矿 RB-SR年龄 成矿物质 岩石圈拆沉 板内造山 成矿潜力 矿产勘查工程 北秦岭 河南 

分 类 号：P597.3[天文地球—地球化学] P612[天文地球—地质学]