西藏雄村矿集区侏罗纪斑岩磷灰石矿物化学特征对新特提斯洋俯冲成矿作用的指示
投稿时间:2017-04-26  修订日期:2017-06-26  点此下载全文
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作者单位E-mail
谢富伟 中国地质科学院矿产资源研究所 xiefuwei@hotmail.com 
唐菊兴 中国地质科学院矿产资源研究所  
郎兴海 成都理工大学地球科学学院  
中文摘要:雄村矿集区位于西藏冈底斯成矿带南缘,区内成矿作用与新特提斯洋俯冲作用有关,现已勘查评价了一个大型还原性斑岩铜金矿床(Ⅰ号矿体)和一个大型氧化性斑岩型铜金矿床(Ⅱ号矿体)。为了查明引起Ⅰ、Ⅱ号矿体成矿特征差异的原因和含矿斑岩的区别标志,本文选取Ⅰ、Ⅱ号矿体含矿斑岩和非含矿斑岩中磷灰石为研究对象,通过对三套斑岩磷灰石单矿物的挑选、阴极发光照相(CL)和电子探针分析(EMPA),提出了磷灰石中Cl含量受控于共存硅酸盐熔体组分,Ⅰ、Ⅱ号矿体含矿斑岩比非含矿斑岩具有更高的Cl/F(分别为0.76、0.26、0.07),高的Cl含量对促进Cu、Au的溶解和迁移具有重要作用的新认识;含矿斑岩磷灰石高Cl低S指示金属元素Cu、Au可能以Cl的络合物为主进行迁移([CuCl2]-、[CuCl]0、[AuCl2]-);Ⅰ、Ⅱ号矿体含矿斑岩氧逸度低于非含矿斑岩,含矿斑岩较低的氧逸度可能指示成矿过程可能发生了结晶硫化物相的预富集;雄村矿集区Ⅰ、Ⅱ号矿体含矿斑岩磷灰石与非含矿斑岩相比具有更高的Mn、Ca、Cl含量,更低的Si、S、F含量,可以作为含矿斑岩的判别标志,对指导区域与新特提斯洋俯冲有关的斑岩型铜金矿床找矿突破有重要义。
中文关键词:雄村矿集区、磷灰石、氧化性/还原性斑岩型矿床、侏罗纪斑岩、新特提斯洋、冈底斯成矿带
 
Apatite geochemistry of Jurassic porphyry at Xiongcun district, southern Gangdese porphyry copper belt: Implications for Neo Tethys mineralization
Abstract:The Xiongcun ore district is located in the southern margin of the Gangdese metallogenic belt, Tibet. The mineralization in Xiongcun district where a large reduction porphyry copper gold deposit (No.Ⅰ orebody) and a large oxidized porphyry copper gold deposit(No.Ⅱorebody) have been are explored and evaluated related to the subduction of the Neo Tethys. In order to find out the difference of ore forming characteristics of No.Ⅰand No.Ⅱorebody and the difference between fertile porphyry and barren porphyry, we selected apatite of NO.Ⅰand No.Ⅱfertile porphyries and barren porphyry as the research object. Through the selection of apatite of three porphyries, cathodoluminescence (CL) and electron probe microanalysis (EMPA), we have found that the content of Cl in apatite is controlled by the composition of coexisting silicate melt and No.Ⅰand No.Ⅱ fertile porphyry have higher Cl/F than barren porphyry (0.76, 0.26, 0.07, respectively) which indicate high Cl content plays an important role in promoting the dissolution and migration of Cu and Au. The high Cl and low S in apatite of fertile porphyries indicate that the Cu and Au may migrated mainly in the Cl complex such as [CuCl2]-、[CuCl]0、[AuCl2]-. The oxygen fugacity of fertile porphyries is lower than barren porphyry and the low oxygen fugacity of fertile porphyries may indicate that saturation of the magma with sulphide may occurred in the mineralization process. Compared with barren porphyry, the apatite of fertile porphyries have higher contents of Mn, Ca, Cl, and lower content of Si, S、F, which can been used as an indicator mineral for mineral exploration related the subduction of the Neo Tethys in the southern margin of the Gangdese metallogenic belt.
keywords:The Xiongcun ore district  Apatite  oxidized/reduced porphyry copper gold deposit Jurassic porphyry  Neo-Tethys ocean, the Gangdise metallogenic belt
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