川西呷村黑矿型多金属矿床热液体系稀土元素组成特征  

COMPOSITIONAL CHARACTERISTICS OF RARE EARTH ELEMENTS IN THE PALEOGEOTHERMAL SYSTEM OF THE GACUN "KUROKO" POLYMETALLIC DEPOSIT, WESTERN SICHUAN

作　　者：别风雷[1] 李胜荣[1] 孙岱生[1] 侯增谦[2] 苏文超[3] 英基丰 

机构地区：[1]中国地质大学,北京100083 [2]中国地质科学院,北京100037 [3]中国科学院地球化学研究所,贵阳550002 [4]中国科学院地质研究所,北京100029

出　　处：《矿物学报》2000年第3期233-241,共9页Acta Mineralogica Sinica

基　　金：国家攀登预选项目!(批准号 :95 预 3 9);国家自然科学基金项目!(批准号 :49873 0 13 )

摘　　要：本文首次测定了呷村黑矿矿石中流体包裹体的REE组成 ,计算了与含矿流纹岩系熔体平衡的岩浆热液REE含量。主成矿期流体具有轻稀土富集、Eu明显正异常的特点 ,但岩浆热液却具有明显的Eu负异常特征 ,结合热液体系氧同位素及稀土元素交换反应模拟 ,表明岩浆热液不是直接的成矿热液。蚀变围岩具显著的Eu正异常 ,其它稀土元素出现亏损。蚀变反应水 /岩比值较大 ,蚀变岩中的REE组成反映了成矿热液REE的特点 ,且REE亏损程度与蚀变强度、流体 /岩石比值呈正相关。The REE in fluid inclusions from the Gacun superlarge Ag\|polymetallic deposit have been determined for the first time by ICP\|MS. The chondrite\|normalized REE patterns in fluid inclusions of the main mineralization stage are characterized by light REE enrichment and remarkable positive Eu anomaly. Similar profiles have been found in other submarine hydrothermal solutions from the East Pacific rise and the mid\|Atlantic ridge, indicating the fluids share much in common in geochemical characteristics. Because of CO\-2 enrichment at the silification\|calcite stage, the REE contents at this stage are higher than those of others. It is extremely likely that Eu in the main ore\|forming solution is divalent. Temperature, oxygen fugacity and pH control the positive Eu anomaly in high\|temperature acidic solutions, but independent of rock type. While REE contents are possibly controlled by the pressure in the water\|rock interaction zone. Altered rhyolites show positive Eu anomaly in contrast to negative Eu anomaly in unaltered rocks. In addition, the degree of REE depletion is positively correlated with alteration intensity and fluid/rock ratio. Calculations of REE concentrations in hydrothermal fluids in equilibrium with the magmatic rocks indicate that the coexisting aqueous phase in equilibrium with rhyolitic melts did not form the ore\|forming fluids because its REE patterns show significant differences from the latter. Moreover, the oxygen isotope data, as well as the simulating model of interaction between rhyolites, seawater and magmatic fluid will lead to the same conclusion.

关 键 词：黑矿 成矿流体 稀土元素 多金属矿床 

分 类 号：P618.205[天文地球—矿床学]