投稿时间：2015-06-09
修订日期：2016-12-24
网络发布日期：2017-03-11
中文摘要:中国与早前寒武纪条带状铁建造有关的磁铁富矿集中分布在辽宁鞍本地区，主要由条带状铁建造经过后期热液改造而成，有去硅富铁和铁质活化再富集2种成因，前者以弓长岭铁矿床二矿区的富铁矿为代表，富铁矿的成矿时代为1.84 Ga左右；后者以齐大山铁矿床樱桃园矿区的富铁矿（樱桃园富铁矿）为代表，但是该富铁矿的成矿时代还不清楚。为了探讨铁质活化再富集型富铁矿的成矿时代，笔者对齐大山铁矿区的辉钼矿进行Re-Os同位素测年。该矿区的辉钼矿有3种产出方式：第一种产于花岗伟晶岩中，呈巨晶辉钼矿集合体；第二种为蚀变岩中石英透镜体边部薄膜状辉钼矿；第三种产于混合花岗岩中的石英脉中，呈浸染状产出。第一种辉钼矿的年龄（2503±33）Ma~（2538±36）Ma，代表了条带状铁建造铁质活化再富集形成富铁矿的主要时期，形成于2.5 Ga左右的华北克拉通发生岩浆、变质作用与克拉通化时期，钼来自地壳，佐证了新太古代末华北克拉通的第一次克拉通化主要是壳内物质的重组；第二种辉钼矿的年龄为（2088±28）Ma，其成矿物质来自地壳，佐证了华北克拉通2.3~1.95 Ga的裂谷-俯冲-增生-碰撞的陆内造山事件也主要是壳内物质的重组；第三种辉钼矿的年龄为（1834±28）Ma~（1853±29）Ma，与弓长岭二矿区"去硅富铁"型富铁矿的成矿时代一致，其成矿物质来自地壳，但混有地幔组分，佐证了1.85~1.65 Ga的华北克拉通基底抬升、镁铁质岩墙群侵入、裂陷槽和裂谷形成有地幔物质的参与。
Abstract:The high-grade iron ore deposits associated with early Precambrian banded iron formation are mainly distributed in Anshan-Benxi area of Liaoning Province. The ore is mainly composed of banded iron formation by the late hydrothermal reformation. There are two geneses:the loss of the silicon-rich iron and iron activation and enrichment, the former iron ore is represented by high-grade iron ore of No.2 digging of the Gongchangling iron deposit, with the metallogenic epoch of the high-grade iron ore being about 1.84 Ga; the latter iron ore is represented by high-grade iron ore of the Qidashan iron deposit, but its metallogenic epoch is unclear. In order to investigate the metallogenic epoch of high-grade iron ore of iron activation and enrichment genesis, the authors studied the molybdenites from the Qidashan iron ore district and Re-Os isotopic dating. There are three types of molybdenum in the Qidashan iron deposit:the first type is the huge molybdenite assemblage in the granite pegmatite, the second type is the molybdenite of thin layers in the quartz lens of chlorite quartz schist, and the third type is the quartz molybdenite vein in the mixed granite. The Re-Os model ages of the first type molybdenite is (2503±33) Ma~(2538±36) Ma, representing the metallogenic epoch of high-grade iron ore of iron activation and enrichment genesis, indicating that the North China Craton experienced magmatic metamorphism and cratonization geological events at 2.5 Ga, the molybdenite was derived from crust, and supporting the argument that the first cratonization of the North China Craton was mainly the reconstruction of the shell material in the late Neo-Archaean. The Re-Os model age of the second type molybdenite is (2088±28) Ma, indicating that the North China Craton experienced the rift valley-intracontinental subduction-hyperplasia-collision orogenic event, and the molybdenite was derived from the crust. The Re-Os age of the third type molybdenite is (1834±28) Ma~(1853±29) Ma, corresponding to the metallogenic epoch of high-grade iron ore of 'silicon-lost rich iron ore' from No.2 digging of the Gongchangling iron deposit formed during early Proterozoic. This suggests that the molybdenite was derived from the crust but was mixed with a little mantle components, which supports the argument that North China Craton basement was uplifted, the mafic dyke intruded, and the formation of the chasmic trough and rift valley had the participation of mantle materials.
keywords:geochemistry Re-Os isotopic dating molybdenite high-grade iron ore banded iron formations Qidashan in Liaoning
文章编号：
中图分类号：P618.31
文献标志码：
基金项目:本文得到国家"973"项目（编号：2012CB416801）和国土资源部公益性行业科研专项（编号：200911007-15、201111002）联合资助
引用文本：
刘明军,曾庆栋,李厚民,李立兴,文屹,姚良德,高业舜.2017.辽宁鞍本地区铁质活化再富集成因富铁矿的成矿时代——齐大山铁矿床辉钼矿Re-Os年龄证据[J].矿床地质,36(1):237~249LIU MingJun,ZENG QingDong,LI HouMin,LI LiXing,WEN Yi,YAO LiangDe,GAO YeShun.2017.Metallogenic epoch of high-grade iron ore deposits of iron activation and enrichment genesis in Anshan-Benxi area of Liaoning: Re-Os isotopic dating evidence of molybdenite from Qidashan iron deposit[J].Mineral Deposits36(1):237~249
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