喀喇昆仑火烧云深成菱锌矿矿床地质特征及成因
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本文为中国地质调查局地质调查项目(编号:DD20190606,12120115065601,1212011121040)的成果。


Geological characteristics and genesis of the Huoshaoyun hypogene smithsonite deposit, Karakoram Mountains, northwest China
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    摘要:

    新疆和田火烧云矿床是青藏高原西部新发现的重要超大型矿床之一,是迄今我国规模最大的锌(铅)矿床,同时也是全球罕见的巨型菱锌矿矿床,累计探明铅锌资源储量超过1800万吨,因其经济价值巨大,矿床成因引人注目。详实的野外地质剖面和钻孔岩芯观察证实,容矿围岩龙山组由泥晶灰岩、砂屑灰岩、鲕粒灰岩和生物碎屑灰岩等组成,广泛发育鸟眼构造、窗格构造和平底晶洞构造,指示沉积环境为中侏罗世碳酸盐岩台地滨海—潮坪的滩坝(介壳滩、鲕粒滩)高能环境。矿区已发现上、下两个含矿层,20余个矿体。下含矿层菱锌矿主矿体储量占比超过95%。矿体呈透镜状、似层状产出,小角度穿切围岩地层。矿石矿物以菱锌矿为主,少量白铅矿和方铅矿;脉石矿物以方解石为主,少量石膏。菱锌矿矿石发育交代、自形—半自形结晶结构,块状、晶洞、条带状和斑马状构造。 火烧云超大型矿床形成经历了阶段Ⅰ菱锌矿(Sm1)、阶段Ⅱ菱锌矿(Sm2)—(方铅矿)和阶段菱锌矿(Sm3)—Ⅲ方铅矿(铅矾)三个连续成矿阶段,其中主成矿阶段菱锌矿(Sm1)占比80%以上。矿区灰岩及碳酸盐矿物碳—氧同位素分析结果表明,菱锌矿基本继承了主岩灰岩的碳—氧同位素,结合菱锌矿矿石交代结构特征,证实火烧云矿床属于后生热液交代成因。基于菱锌矿矿石矿相学和碳—氧同位素特征,本文首次提出并详细讨论了火烧云矿床的菱锌矿化成矿作用,即富锌少铅贫硫(S2-)热液通过微米级方解石溶解—菱锌矿沉淀藕合作用交代龙山组灰岩。因此,火烧云矿床既不是发生氧化的MVT锌矿床,也不是SEDEX锌碳酸盐矿床,而是一类原生深成(hypogene)热液交代锌碳酸盐矿床。

    Abstract:

    The Huoshaoyun deposit in Hotan County, Xinjiang, is one of the important superlarge(giant) deposits which have been found in the western part of the Qinghai—Xizang(Tibet) Plateau in recent years. It is the largest zinc—lead deposit in China and the rare giant smithsonite deposit in the world. The proved lead and zinc resource reserves of the Huoshaoyun deposit are more than 18 million tons, it is thus especially notable for the deposit origin due to its great economic value. Based on the detailed observation of the outcrop of orebody and a number of drilling cores, the host Longshan Formation consists of micrite, calcarenite, oolitic limestone and bioclastic limestone, with well developed bird’s eye structure, fenestral cavities and geopetal stromatactis structure, indicated that the Longshan Formation was formed in a beach environment (shell, oolitic) of the Middle Jurassic carbonate platform. There are over twenty orebodies within two ore- bearing layers have been found in the ore district, and the main orebody reserves account for more than 95 percent of the total. The zinc orebodies appear to be stratiform and lenticular with a very small angle to the host carbonate bedding. The smithsonite is the main ore mineral, a few galena and cerussite; calcite is the main gangue mineral, a few gypsum. The smithsonite ores are massive, vuggy, banded, with the idiomorphic—semi- idiomorphic microcrystalline, metasomatic and zebra texture. The formation of the large, high- grade Huoshaoyun Zn deposit occurred during three successive metallogenic stages with smithsonite(Sm1), smithsonite(Sm2)—(galena) and smithsonite(Sm3)—galena (anglesite), main stage of smithsonite ore (Sm 1) is composed of smithsonite 80% of the total. The carbon and oxygen isotopes of the simthsonite and the host limestone are similar, confirming the simthsonite dependence on the host limestone. The carbon—oxygen isotopic characteristics together with the metasomatic texture of the smithsonite ore, support the hypogene hydrothermal metasomatic origin of Huoshaoyun Zn deposit. Based on the detailed petrographic and carbon—oxygen isotopic study, a new type of hypogene smithsonite mineralization for the Huoshaoyu deposit is proposed in this paper. Through the coupling process with calcite (limestone) dissolve—smithsonite precipited, the hydrothermal fluid with Zn- rich,Pb- low and S2- - poor metasomatic replace the host limestone of the Longshan Formation in the Huoshaoyun ore district. Thus, the Huoshaoyun deposit is not formed by supergene oxidation of a MVT zinc sulfide deposit, nor a SEDEX zinc carbonate deposit, it is a hypogene zinc carbonate deposit.

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高兰,杜勇,宋林山,任晓栋,丁建华,隗含涛,崔宁,张琪.2020.喀喇昆仑火烧云深成菱锌矿矿床地质特征及成因[J].地质论评,66(2):365-379,[DOI].
GAO Lan, DU Yong, SONG Linshan, REN Xiaodong, DING Jianhua, WEI Hantao, CUI Ning, ZHANG Qi.2020. Geological characteristics and genesis of the Huoshaoyun hypogene smithsonite deposit, Karakoram Mountains, northwest China[J]. Geological Review,66(2):365-379.

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  • 收稿日期:2019-01-07
  • 最后修改日期:2019-12-03
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  • 在线发布日期: 2020-03-16
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