新疆西天山阔库确科铁铜矿区成矿岩体锆石微量元素地球化学特征及其地质意义  

Zircon trace element geochemical characteristics and geological significance of ore forming rocks in Kuokuqueke iron copper ore district,western Tianshan,Xinjiang

作　　者：顾枫华 章永梅[2] 彭义伟[3] 王佳琳[2] GU FengHua;ZHANG YongMei;PENG YiWei;WANG JiaLin(MNR Key Laboratory of Metallogeny and Mineral Resource Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Chengdu University of Technology,College of Earth Sciences Chengdu 610095,Sichuan,China)

机构地区：[1]中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质大学(北京),地球科学与资源学院,北京100083 [3]成都理工大学,地球科学学院,四川成都610095

出　　处：《矿床地质》2023年第6期1159-1174,共16页Mineral Deposits

基　　金：国家自然科学基金项目(编号:42202094、42130804)资助。

摘　　要：新疆西天山北缘的博罗科努晚古生代岛弧带出露大量中酸性侵入体,并发育一系列斑岩-矽卡岩型铁铜多金属矿床。文章对该岛弧带中部阔库确科矽卡岩型铁铜矿床成矿岩体中的锆石开展了微量元素地球化学研究,查明了锆石成因、形成物理化学条件及其对成矿的启示意义等。数据显示,与成矿密切相关的正长花岗岩和闪长岩中锆石均表现为重稀土元素富集、轻稀土元素亏损,正长花岗岩中锆石的∑REE介于(627~1625)×10^(-6),闪长岩中锆石的∑REE介于(345~1439)×10^(-6)。锆石Ti温度计显示正长花岗岩锆石的结晶温度集中在598~810℃;闪长岩锆石结晶温度为651~932℃,正长花岗岩的氧逸度(ΔFMQ+4.25)高于闪长岩(ΔFMQ-1.01)。成矿岩体锆石均形成于封闭的岩浆体系中,主要为岩浆锆石,少量闪长岩中的锆石可能在岩浆晚期遭受了富集轻稀土元素的热液改造。锆石形成构造背景属于大陆岛弧环境。成矿岩体锆石的Ce^(4+)/Ce^(3+)值明显高于区域内不成矿岩体的Ce^(4+)/Ce^(3+)值,其中正长花岗岩锆石中更高的Ce^(4+)/Ce^(3+)值表明,阔库确科矿区内志留系与正长花岗岩发生接触交代形成的矽卡岩中可能有更大的Cu成矿潜力。The Late Paleozoic Boluokenu island arc belt,located at the northern margin of the West Tianshan Mountain,Xinjiang Autonomous Region,China,hosts abundant mineral resources and intermediate-acid intrusions.In this paper,the trace element geochemistry of zircons from ore related intrusions in the Kuokuqueke skarn type iron-copper deposit in the central part of the island arc belt has been studied,and the genesis,physical and chemical conditions of zircon formation and its implications for mineralization have been identified.The data shows that zircon in syenogranite and diorite closely related to mineralization is enriched in heavy rare earth elements and depleted in light rare earth elements.The∑REE of zircon in syenogranite is(627~1625)×10^(-6),the∑REE of zircon in diorite is(345~1439)×10^(-6).The Ti zircon thermometer shows that the crystallization temperature of zircon in syenogranite is concentrated in range of 598~810℃,and the crystallization temperature of zircon in diorite is concentrated in range of 651~932℃,and the oxygen fugacity of syenogranite(ΔFMQ+4.25)is significantly higher than diorite(ΔFMQ-1.01).The zircons of the ore-forming rocks were formed in a closed magmatic system,mainly magmatic zircons.A small amount of zircons in diorite may have been transformed by LREE enriched hydrothermal in the late magmatic period.The Ce^(4+)/Ce^(3+)values of zircons from ore-forming rocks are significantly higher than those from non ore-forming rocks in the region.Among them,the higher Ce^(4+)/Ce^(3+)values in zircons from syenogranite indicate that there may be greater Cu mineralization potential in the skarns formed by contact metasomatism between the Silurian strata and syenogranite in the Kuokuqueke ore district.

关 键 词：锆石微量元素 氧逸度 成矿岩体 博罗科努成矿带 新疆西天山 

分 类 号：P618.31[天文地球—矿床学]