| 山东沂南金铜铁矿床中的液态不混溶作用与成矿：流体包裹体和氢氧同位素 证据 |
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| 引用本文：李科,李葆华.2010.Immiscibility during mineralization of Yinan Au-Cu-Fe deposit, Shandong Provin ce: Evidence from fluid inclusions and H-O isotopes[J].Mineral Deposits,29(1):43~57 |
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| 基金项目:国家自然科学基金（40772060，40930423，40873036）、国家重点基础研究发展计 划（2009CB421003-01）、长江学者和创新团队发展计划、高等学校学科创新引智计划（B07 011）、中国地质大学地质过程与矿产资源国家重点实验室基金(GPMR0531) |
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| 中文摘要:沂南矽卡岩型金铜铁矿床产于燕山期中酸性侵入岩与新太古界—寒武 系层接触带附近。氢、氧同位素研究表明，早期干矽卡岩阶段（Ⅰ）和湿矽卡岩-磁铁矿阶段（Ⅱ）的成矿流体主要为岩浆水，晚期石英_硫化物阶段（Ⅲ）和碳酸盐阶段（Ⅳ）的成矿流体则显 示有大气降水混入的岩浆水特点。流体包裹体研究表明，成矿各阶段热液矿物中的包裹体类 型丰富，以气液两相盐水包裹体、含子晶多相包裹体和CO2-H2O包裹体为主，次为纯液相水包裹体和纯气相水包裹体，偶见晶质熔融包裹体。由Ⅰ→Ⅱ→Ⅲ→Ⅳ阶段，气液水包裹 体均一温度（520～430℃→430～340℃→250～190℃→190～130℃）呈现逐渐降低的趋 势。在Ⅰ 、Ⅱ阶段的石榴子石和绿帘石中，晶质熔融包裹体与同期次捕获的具不同气相分数的气液 水包裹体及含子晶的多相包裹体共生，表明它们被捕获时是一种熔体与流体共存的不混溶状态。在Ⅲ阶段的石英（少量Ⅱ阶段的绿帘石）中，常见气相充填度变化很大的气液水包裹体与同期次捕获的纯液相水包裹体、纯气相水包裹体、含子晶的多相包裹体以及CO2-H2O包裹体共生，且共生的不同类型包裹体均一温度相近，表明此阶段成矿流体曾发生过广泛的沸腾（不混溶）。因而认为，在沂南矿床由岩浆结晶分异到热液成矿的整个演化过程中，可能先后经历了两 种液态不混溶作用，早期岩浆熔融体与气液相流体的不混溶导致含矿气水热液的析出，晚期气相与液相组分的不混溶（沸腾）则导致了金、铜、铁的沉淀。 |
| 中文关键词:地球化学 液态不混溶 沸腾 流体包裹体 氢、氧同位素 沂南金铜铁矿床 山东 |
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| Immiscibility during mineralization of Yinan Au-Cu-Fe deposit, Shandong Provin ce: Evidence from fluid inclusions and H-O isotopes |
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| Abstract:The Yinan skarn-type Au-Cu-Fe deposit occurs at the contact zone between the Yanshanian intrusives and the Neo-Archean-Cambrian sedimentary rocks. Hydrogen and oxygen isotopic geochemistry shows that the early ore-forming fluids of the anhydrous skarn stage (Ⅰ) and the hydrous skarn-magnetite stage (Ⅱ) were mainly derived from magmatic water, whereas the late fluids of the quartz-sulfide stage (Ⅲ) and the carbonate stage (Ⅳ) came mainly from magmatic water mixed with small amounts of meteoric water. Various types of fluid inclusions, which include mainly vapor-or liquid-rich two-phase aqueous inclusions, daughter minerals-bearing multiphase inclusions and CO2-H2O inclusions, subordinately liquid inclusions and vapor inclusions, and minor melt inclusions, are present in minerals of different stages. The homogenization temperature of the aqueous fluid inclusi ons decreases from stage Ⅰ(520～430℃), through stage Ⅱ (430～340℃) and Ⅲ(250～190℃), to stage Ⅳ (190～130℃). The coexistence of melt inclusions with simult a neously trapped vapor-or liquid-rich two-phase aqueous inclusions and daughter minerals-bearing multiphase inclusions in garnet and epidote of stages Ⅰ and Ⅱ suggests an immiscibility between silicate melt and hydrothermal fluid. In the quartz of stage Ⅲ, the aqueous fluid inclusions with various vapor/liquid ratios (<10％ or >65％) commonly coexist with simultaneously trapped liquid inclusions,vapor inclusions, daughter minerals-bearing multiphase inclusions and CO2-H2O inclusions, and different kinds of fluid inclusions have similar homogenization temperatures. This indicates that boiling extensively took place at stage Ⅲ. It is thus suggested that two kinds of immiscibility occurred in the process from magmatic crystallization and differentiation to hydrothermal mineralization in the Yinan ore deposit. The earlier immiscibility between silicate melt and hydrothermal fluid caused the escape of ore-bearing fluids from the magma, wher eas the later immiscibility between gaseous and liquid phases (boiling) resulted in Au-Cu-Fe mineralization. |
| keywords:geochemistry, immiscibility, boiling, fluid inclusions, hydrogen and oxygen isotopes, Yinan Au-Cu-Fe deposit, Shandong |
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