贵州云炉河坝地区铅锌矿床元素地球化学特征、碳氧同位素组成及其地质意义

金翔霖++孟昌忠++冷成彪+齐有强++唐永永张海陈星

文章编号：16726561（2016）06077813

摘要：黔西北是中国川滇黔铅锌成矿域的一个重要组成部分，以该区研究程度较低的云炉河坝地区为研究对象，采用元素地球化学和碳氧同位素地球化学分析方法，对区内典型铅锌矿床（如昊星、顺达、富强和狮子洞等）进行了研究。成矿元素和稀土元素分析结果表明，包括赋矿围岩在内的区域各时代地层中的Pb、Zn、Cu等成矿元素含量普遍低于地壳克拉克值，不可能构成铅锌矿床的主要物质来源，结合前人S、Pb同位素研究，推测该区铅锌矿床的成矿物质可能主要来自于基底岩石。碳氧同位素分析结果表明，铅锌矿石和赋矿围岩的碳氧同位素组成整体上均接近海相碳酸盐岩范围，说明相关流体主要来自于海相碳酸盐的溶解作用。然而，矿石与围岩相比却具有相对更高的δ18O值，表明成矿流体并非直接源自于赋矿地层，而更可能来自于深源流体的长距离迁移。此外，个别方解石显示较低的δ13C值（-10.9‰～-8.1‰，PDB），接近沉积有机物的碳同位素组成范围，表明其受到了有机物脱羟基作用的影响。

关键词：铅锌矿床；元素地球化学；碳氧同位素；碳酸盐岩；成矿元素；深源流体；贵州

中图分类号：P618.4文献标志码：A

Element Geochemical Characteristics and CO Isotopic Compositions

of PbZn Deposit in Yunluheba Area of Guizhou and Their Geological Implications

JIN Xianglin1， MENG Changzhong1， LENG Chengbiao2， QI Youqiang2， TANG Yongyong2， ZHANG Hai1，2， CHEN Xing1

（1. No.113 Geological Team， Guizhou Provincial Bureau of Geology and Mineral Resources， Liupanshui 553001，

Guizhou， China； 2. State Key Laboratory of Ore Deposit Geochemistry， Institute of Geochemistry， Chinese Academy of Sciences，

Guiyang 550081， Guizhou， China）

Abstract： Northwestern Guizhou is an important area in SichuanYunnanGuizhou PbZn metallogenic domain. Yunluheba area in the northwestern Guizhou was taken as the object of the study. The element geochemical characteristics and CO isotopic compositions of typical PbZn deposits in the area including Haoxing， Shunda， Fuqiang and Shizidong were studied. The results of metallogenic and earth rare elements show that the contents of metallogenic elements （Pb， Zn and Cu， etc.） from the strata with different ages including host rocks are generally lower than the Clark value of the continental crust； PAASnormalized REE patterns have a wide range with weak negative Ce anomaly and noinfluencing from hydrothermal fluid. It is suggested that all the strata including host rocks do not supply the material sources for PbZn deposits， but the characteristics are derived from the sedimentary environment. According to the previous result of S and Pb compositions， it is inferred that the main material sources of PbZn deposits may be the basement rocks. The CO Isotopic compositions show that dolomite has relatively high δ13C values （-1.0‰1.1‰， PDB） and δ18O values （20.4‰23.6‰， VSMOW）， whereas the asphalt has relatively low δ13C values （-6.0‰3.9‰） and δ18O value （15.2‰）； most of the calcites have δ13C values of -4.1‰-0.5‰ and δ18O values of 15.2‰21.3‰， which are between those of dolomite and asphalt； CO Isotopic values of PbZn and host rocks are consistent with those of marine carbonate rocks as a whole， suggesting that they are mainly derived from the dissolution of marine carbonate. PbZn rocks have higher δ18O values than those of host rocks， suggesting that metallogenic fluids are not directly derived from host strata， and may be derived from the longdistance migration of deep source fluid. In addition， the individual calcite has lower δ13C values （-10.9‰-8.1‰）， which are consistent with C isotopic value of sedimentary organic material， so that the calcite suffers the dehydroxylation of organic material.

Key words： PbZn deposit； element geochemistry； CO isotope； carbonatite； oreforming element； deep source fluid； Guizhou

0引言

密西西比河谷（MVT）型铅锌矿床是一类后生、层控、以碳酸盐岩为赋矿围岩的矿床，资源量占全球铅锌总量的25%[15]。川滇黔铅锌多金属成矿域位于扬子地块西南缘，是中国重要的铅锌（银镉）等金属的生产基地[611]。……