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引用本文:梁涛,卢仁,杨楠,王莉,温静静. 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[J]. 中国地质, 2020, 47(2): 406-425.
LIANG Tao,LU Ren,YANG Nan,WANG Li,WEN Jingjing. 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[J]. Geology in China, 2020, 47(2): 406-425(in Chinese with English abstract).
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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
梁涛1,2, 卢仁1,2, 杨楠1,2, 王莉1,2, 温静静1,2
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
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Δβγ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。
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
DOI:10.12029/gc20200210
分类号:P597.3;P612
基金项目: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。
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
LIANG Tao1,2, LU Ren1,2, YANG Nan1,2, WANG Li1,2, WEN Jingjing1,2
1.General Institute of Non-ferrous Metals Geologic Exploration, Zhengzhou 450052, Henan, China;2.Key Laboratory of Deep Ore-prospecting Technology Research for Non-ferrous Metals of Henan Province, Zhengzhou 450052, Henan, China
Abstract:
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. The 87Rb/86Sr and 87Sr/86Sr 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 87Sr/86Sr ratios are in the range of 0.711025±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 -130Ma in early Cretaceous. The δ18OV-SMOW and δDV-SMOW values of 3 quartz samples are 11.6‰-12.1‰ and -60.9‰—-42.5‰, respectively. Their δ18OH2O values range from 2.16‰ to 2.66‰, suggesting that ore-forming fluids of the Gaozhuang gold deposit were a mixed source. The δ34SV-CTD values of 6 pyrite samples are from -2.8‰ to -1.6‰ with a tower shape in the δ34S histogram, which indicates a mantle source. The ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb 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 206Pb/204Pb-207Pb/204Pb and 206Pb/204Pb-208Pb/204Pb 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 Δβγ 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 Gaozhuang gold deposit was closely related to Yanshanian intraplate (intracontinental) orogenesis of northern Qinling Mountain. The Gaozhuang gold deposit, the Yanzhen granitic intrusive and the Gaozhuang granitic aplite are all products of regional lithosphere delamination. Deep fluids were rapidly discharged, and diverse sources of metallogenic materials at different depths were connected in the process of regional lithosphere delamination. The Gaozhuang gold deposit was formed when the mixed fluids stopped moving in shallow crust. It is suggested that the deep part beneath the Gaozhuang gold deposit and the Yanzhen area possessed endogenetic metallogenic potential with rapid discharging of deep fluids controlled by regional lithosphere delamination.
Key words:  Gaozhuang gold deposit  Rb-Sr isochron age  intraplate orogenesis  metallogenic material  lithosphere delamination  mineralization potential  mineral exploration engineering  northern Qinling Mountain  Henan Province