青海沱沱河地区那日尼亚铅锌矿床地质与地球化学研究  

Geological and geochemical studies of the Nariniya lead-zinc deposit in Tuotuohe area,Qinghai Province

作　　者：张羽中 宋玉财[2] 侯增谦[2] 庄天明[3] 李连松 贾宗涌 闫明 陈生彦 

机构地区：[1]东华理工大学地球科学学院,江西南昌344000 [2]中国地质科学院地质研究所,北京100037 [3]中国地质大学地球科学与资源学院,北京100083 [4]青海省第五地质矿产勘查院,青海西宁810028

出　　处：《岩石矿物学杂志》2013年第3期291-304,共14页Acta Petrologica et Mineralogica

基　　金：国家重点基础研究规划项目(2009CB421008,2011CB403104);国家自然科学基金(41273050,U0933605,41102040);IGCP/SIDA600项目;国土资源大调查项目(1212011220908,1212011121065)

摘　　要：那日尼亚铅锌矿床是在青藏高原近来发现的、与钾质火山岩岩浆活动有关的矿床。分析表明，新鲜赋矿火山岩Si02含量62．9％～68．6％，K20含量5．1％-5．8％，属钾玄岩系列，其轻稀土和大离子亲石元素相对富集，Nb、Ta、Ti等元素强烈亏损，Sr／Y—Y图解投影点落人已报道的藏北钾质一超钾质岩分布范围之内，指示岩浆起源于富集地幔或受下地壳物质混染的软流圈地幔。矿床的矿体呈脉状出现在粗面岩中，由一系列细脉状的矿石构成，硫化物主要是方铅矿和黄铁矿，也含少量闪锌矿和黄铜矿，脉石矿物以石英为主，并发育方解石、白云石、绢云母，围岩蚀变以白云母化和黄铁矿化为主。石英中流体包裹体为盐水体系，均一温度为170300℃、盐度为2％～9％NaCleq（质量分数），指示成矿流体可能来自岩浆活动驱动的地表水；方铅矿δ^34S 值介于-0．1～1．7之间，铅同位素组成落人藏北钾质一超钾质岩石的组成范围内，指示硫和铅均来自赋矿的钾质火山岩。那日尼亚铅锌矿床与沱沱河地区碳酸盐岩容矿铅锌矿床的地质和地球化学特征差别明显，两者不是一套成矿系统的产物。The Nariniya lead-zinc deposit, recently discovered in the Tibetan Plateau, is genetically linked to the activities of potassic volcanic magma. Studies show that the SiO2 and K2O content of the fresh host rocks is 62.9 %-68.6 % and 5.1% -5.8 %, respectively, indicative of a shoshonitic series. The host rocks are rela- tively enriched in LREE and large iron lithophile elements and strongly depleted in elements such as Nb, Ta, and Ti. The Sr/Y ratios and Y content fall into the range of the potassium-ultrapotassic rocks, which has already been reported. These data suggest that the magma was sourced from enriched mantle or the astheno- sphere mantle which had been contaminated by lower crustal material. Ore bodies occur as NWW-striking veins in volcanic rocks, consisting of galena, pyrite, quartz, calcite, dolomite, and minor sphalerite, chalcopyrite, and sericite. The alteration is dominated by muscovitization and pyritization. Fluid inclusions in quartz belong to a H2O-NaCl system and have the homogenization temperature of 170- 300℃ and the salinity of 2 % -9 % Na- Cleq, which probably represents meteoric water driven by magmatic activity. The δ^34S values of galena are from - 0.1 to 1.7 and the Pb isotopic compositions fall into the range of the potassium-ultrapotassic rocks of northern Tibet, so the sulfur and lead were probably derived from the potassic volcanic rocks. The Nariniya lead-zinc deposit is significantly different from carbonate-hosted lead-zinc deposits in Tuotuohe region in geological and geochemical characteristics, so they belong to different ore-forming systems.

关 键 词：钾质火山岩 地质和地球化学特征 那日尼亚 沱沱河 

分 类 号：P595[天文地球—地球化学] P618.42[天文地球—地质学]