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西天山吐拉苏盆地安山岩中发现岩石包体及地质找矿意义
引用本文:赵晓波,薛春纪,张招崇,王洪刚,李晓钟,米登江.西天山吐拉苏盆地安山岩中发现岩石包体及地质找矿意义[J].地质学报,2012,86(11):1781-1791.
作者姓名:赵晓波  薛春纪  张招崇  王洪刚  李晓钟  米登江
作者单位:中国地质大学(北京),中国地质大学(北京),中国地质大学(北京),中国地质大学(北京),中国冶金地质总局新疆地质勘查院,中国冶金地质总局新疆地质勘查院
基金项目:受“十二五”国家科技支撑计划课题(2011BAB06B02)和中国地质调查局工作项目(1212011085069)资助
摘    要:新疆西天山斑岩型铜矿找矿前景良好,但面临攻坚;吐拉苏盆地是西天山浅成低温热液型金矿集区,晚古生代吐拉苏盆地是北天山洋向南向伊犁板块之下俯冲形成的“西南太平洋型”岛弧环境,在金矿深边部寻找斑岩型铜金矿值得关注。笔者最近在岛弧安山岩中发现硫化物矿化二长斑岩、细晶闪长岩等岩石包体。岩石包体发现于塔乌尔别克金矿区,多呈浑圆体或次棱角状,随机分布于安山岩中,与围岩界线截然,常见安山岩围绕岩石包体形成冷凝边。二长斑岩包体显示似斑状结构,斑晶由斜长石和钾长石组成;细晶闪长岩主要由斜长石和角闪石组成,细晶结构,块状构造;寄主安山岩为斑状结构,斑晶为斜长石和少量角闪石及单斜辉石,基质由短柱状斜长石及少量单斜辉石组成,玻基交织结构。二长斑岩包体、细晶闪长岩包体和寄主安山岩三者具有极为相似的微量元素和稀土元素组成,均富集大离子亲石元素、相对亏损Nb、Ta等高场强元素。这些岩石学和地球化学特点反映岩石包体是岛弧火山喷发过程中从下覆地质体捕掳成因,指示安山岩层之下存在同源斑岩体并可能已发生硫化物矿化。综合考虑吐拉苏盆地铜矿化点、酸性热液蚀变、高硫型和低硫型浅成低温热液金矿的组合关系,认为盆地内发育斑岩-浅成低温热液金铜成矿系统,塔乌尔别克是斑岩型铜金矿找矿重要靶区。

关 键 词:岩石包体  斑岩铜金矿找矿靶区  塔乌尔别克  吐拉苏盆地  新疆西天山
收稿时间:2012/4/10 0:00:00
修稿时间:7/21/2012 2:27:24 PM

Rock Enclaves Discovered in Andesite and its Geological Prospecting Significance, Tulasu basin, western Tianshan
ZHAO Xiaobo,XUE Chunji,ZHANG Zhaochong,WANG Honggang,LI Xiaozhong,MI Dengjiang.Rock Enclaves Discovered in Andesite and its Geological Prospecting Significance, Tulasu basin, western Tianshan[J].Acta Geologica Sinica,2012,86(11):1781-1791.
Authors:ZHAO Xiaobo  XUE Chunji  ZHANG Zhaochong  WANG Honggang  LI Xiaozhong  MI Dengjiang
Affiliation:China University of Geosciences, Beijing,China University of Geosciences, Beijing,China University of Geosciences, Beijing,China University of Geosciences, Beijing,Xinjiang Institute of Exploration, China Bureau of Metallurgical Geology,Xinjiang Geological Prospecting Institute of China Metallurgical geological
Abstract:The succeed exploration of porphyry copper deposit in the western Tianshan, Xinjiang, faces much hope but a difficulty. The Tulasu basin is a concentration area of the epithermal gold deposits in western Tianshan, was a south-west-Pacific-type of island-arc setting during late Paleozoic period as the southward subduction of northern Tianshan ocean to Yili plate. The porphyry Cu-Au deposit could be found at the depth or the adjacent of those epithermal gold deposits. Some sulfide mineralized rock enclaves of monzonite porphyry and fine-crystalline diorite are discovered in the andesite, Tawurbieke gold district, Tulasu basin. The enclaves occur in random distribution, generally round or subangular ship, commonly clear boundaries with the hosted andesite, and result chilled margins of the andesite around the enclaves. The monzonite porphyry enclave exhibits porphyaceous texture, and th phenocryst consisits of plagioclase and K-feldspar. The fine-crystalline diorite enclave is mainly composed of plagioclase and hornblende with aplitic texture and massive structure. The hosted andesite show porphyry texture, and the phenocryst consisits of plagioclase, miner hornblende and clinopyroxene, and the groundplasm are composed of short column plagioclase and miner clinopyroxene with hyalopilitic texture. The monzonite porphyry enclave, the fine-crystalline diorite enclave and the hosted andesite shows a similarity of the rare- and the rare-earth-element composition, such as a pronounced enrichment of Large Ion Lithophile Elements, deficit of High Field Strength Elements. The petrology and geochemistry suggests that the rock enclaves were captured from the underlying body by the eruption process of island-arc magma, and the cognate porphyry body may exist under the andesite strata and the porphyry had been sulfide mineralized. The porphyry-epithermal Cu-Au mettallogenic system might occur in the Tulasu basin, western Tianshan, and the Tawuerbieke may be an important target for porphyry Cu-Au exploration based on the fact of the copper mineralizations, acid hydrothermal alterations, the high-sulfidation and the low-sulfidation epithermal gold deposits in the basin.
Keywords:the rock enclave  the exploration target of porphyry Cu-Au deposit  Tawurbieke  Tulasu basin  western Tianshan  Xinjiang
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