Mineralogy, Geochemistry, and Age Constraints on the Zn-Pb Skarn Deposit of Maria Cristina, Quebrada Galena, Northern Chile
Mineralogy, Geochemistry, and Age Constraints on the Zn-Pb Skarn Deposit of Maria Cristina, Quebrada Galena, Northern Chile
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DOI：
10.2113/gsecongeo.95.6.1185
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发表时间：
2000-09
期刊：
影响因子：
5.8
通讯作者：
F. Lieben;R. Moritz;L. Fontboté
中科院分区：
文献类型：
--
作者：
F. Lieben;R. Moritz;L. Fontboté
描述了智利北方下白垩统Chanarcillo群碳酸盐岩中的Maria Cristina锌铅夕卡岩存款，以提供与邻近（~2 km）重晶石矿床和具有密西西比河谷型亲和力的区域铅锌和钡矿床进行比较的基础。强烈退变质的石榴石（钙铁榴石至Ad 30 Gr 70）、透辉石、绿帘石矽卡岩和含重晶石块状硫化物（闪锌矿-黄铁矿-方铅矿-白铁矿-磁铁矿）产于白垩纪中期钾蚀变二长斑岩的接触处。矽卡岩矿物组成，类似的铜矽卡岩，可能反映侵位在高f O2的背景下。硫化物和重晶石的硫同位素值分别为-8.8 ‰ ~+7.1‰和14.0 ‰ ~ 26.1‰，表明硫的来源不同，硫的来源也不均衡，其中包括岩浆硫。方铅矿的铅同位素比值和重晶石的锶同位素比值表明，不同存款类型具有相似的金属储集层，由下白垩统火山岩或中白垩统侵入岩的夹层构成。热液钾长石40 Ar/39 Ar定年结果表明，成矿时代为94 ~ 90 Ma。
The Maria Cristina Zn-Pb skarn deposit, hosted by carbonate rocks of the Lower Cretaceous Chanarcillo Group in northern Chile, is described to provide a basis of comparison to adjacent (~2 km) barite deposits and regional Pb-Zn and Ba deposits with Mississippi Valley-type affinities. Strongly retrograded garnet (andradite to Ad30Gr70), diopsidic pyroxene, and epidote skarn, and barite-bearing massive sulfides (sphalerite-pyrite-galena-marcasite-magnetite) occur at the contact of potassically altered diorite porphyry of mid-Cretaceous age. The skarn mineral compositions, similar to those of Cu skarns, may reflect emplacement in a high f O2 context. Sulfur isotope values of sulfides (–8.8 to +7.1‰) and barite (14.0–26.1‰) indicate disequilibrium conditions and different sulfur sources, including magmatic sulfur. Lead isotope ratios of galena and strontium isotope ratios of barite indicate a similar metal reservoir for the different ore deposit types, constituted by the intercalated Lower Cretaceous volcanic rocks or mid-Cretaceous intrusive rocks. 40Ar/39Ar dating of hydrothermal K feldspar suggests an age between 94 and 90 Ma for the mineralization.