湖南祁东清水塘铅锌矿床成矿物质来源同位素示踪  

Isotopic Tracer of Ore-FormingMaterial Source from the Qingshuitang Lead-Zinc Deposit,Qidong County,Hunan Province

作　　者：路睿[1,2] 缪柏虎 徐兆文[2] 陆建军[2] 王汝成[2] 左昌虎[2,4] 屈金宝 赵增霞[2] 

机构地区：[1]青海省地质调查局,西宁810001 [2]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学与工程学院,南京210093 [3]江苏省地质调查研究院,南京210018 [4]湖南水口山有色金属有限责任公司,湖南衡阳421513

出　　处：《地质学报》2017年第6期1285-1298,共14页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号:41173050);中国地质调查局调查项目(编号:1212011085407)联合资助的成果

摘　　要：清水塘铅锌矿床位于湖南省祁东县北东部,是一个中型矿床。在详细的野外地质调查基础上,本文通过矿石硫、铅同位素,含矿石英氢、氧同位素和含矿方解石碳、氧同位素等综合研究,探讨清水塘铅锌矿床成矿物质来源和成因。硫同位素研究结果表明,清水塘铅锌矿床中黄铁矿、方铅矿和闪锌矿的硫同位素δ^(34)S介于-7.41‰~2.91‰之间,重晶石的硫同位素δ^(34)S介于11.49‰~12.34‰之间,表明矿石中的硫主要来源于深源岩浆,并受到上部地壳物质的混染。黄铁矿、方铅矿和闪锌矿的Pb同位素^(206)Pb/^(204)Pb介于17.810~18.710之间,^(207)Pb/^(204)Pb介于15.497~15.726之间,^(208)Pb/^(204)Pb介于37.858~38.834之间;其中闪锌矿变化范围略偏大,表明矿石中的铅主要来源于地壳,可能混有少量地幔物质。含矿石英的氢、氧同位素δD_(SMOW)介于-87.4‰^-79.3‰之间,δ^(18)O_(H_2O)介于-8.10‰~0.63‰之间,表明成矿流体以岩浆水为主,晚期有大气降水的混入。含矿方解石的碳、氧同位素δ^(13)C_(VPDB)介于-5.3‰^-4.6‰之间,δ^(18)O_(SMOW)介于12.30‰~13.48‰之间;与地层灰岩的δ^(13)C_(VPDB)(0.9‰~2.6‰),δ^(18)O_(SMOW)(21.86‰~23.39‰)不一致;说明成矿流体中的碳主要来自深源岩浆。以上研究表明,清水塘铅锌矿床的成矿物质主要来自地壳熔融形成的岩浆,混合作用是成矿的主要机制。Qingshuitang Pb-Zn deposit, a medium-size deposit, is located in the northeast of Qidong County, Hunan Province. Based on field geological investigation, we carried out the sulfur and lead isotopic compositions of the ores, hydrogen and oxygen isotopic compositions of the ore-bearing quartz, as well as carbon and oxygen isotopic compositions of the ore-bearing calcites and limestone, to discuss the ore-forming material source and genesis of the Qingshuitang Pb-Zn deposit. The δ^34S values of pyrite, galenite and sphalerite range from -7.41 to 2.91 ‰, and the δ^34 S values of barite range from 11.49 to 12.34 ‰, indicating a deep source for magma and may be partly contaminated by the crustal substance. The 206Pb/204Pb, 207Pb/204 Pb and 208 Pb/ 204Pb ratios for ores range from of 17.810 to 18.710, 15.497 to 15.726, 37.858 to 38.834, respectively, indicating Pb was mainly derived from crust and may be mixed some mantle source. The δDSMOW and δ^18O H2O values of ore-bearing quartz range from -87.4 to -79.3‰ and from 8.10 to 0.63‰, respectively, indicating that the ore forming fluid came mainly from a magmatic hydrothermal source, with meteoric water added in the late mineralization stage. The δ^13CVPDB values for limestone in strata range from 0.9 to 2.6‰, the δ^18OSMOW values range from 21.86 to 23.39 ‰; The δ^13CVPDB and the δ^18O SMOW values of ore bearing calcites range from -5.3 to -4.6 ‰ and from 12.30 to 13.48‰, respectively, which are not consistent with δ^13C PDB（0.9 ‰ ～ 2.6 ‰） and δ^18O SMOW（21.86 ‰ ～ 23.39 ‰）of the limestone, indicating that carbon in the ore forming fluid mainly originated from deep magma. The research above shows that the ore-forming materials of the Qingshuitang deposit mainly came from the partial melting of the crust and the mixing effect was the main ore-forming mechanism.

关 键 词：同位素示踪 成矿物质来源 矿床成因 清水塘铅锌矿床 湖南省祁东县 

分 类 号：P618.4[天文地球—矿床学] P629[天文地球—地质学]