新疆准噶尔北缘乔夏哈拉铁铜金矿床成岩成矿时代

乔夏哈拉铁铜金矿位于新疆准噶尔北缘,矿体赋存于中泥盆统北塔山组第三岩性段凝灰质砂岩、粉砂岩、大理岩、凝灰岩、玄武岩及安山岩中。铁矿体呈似层状、扁豆状或透镜状,铜金矿体产于铁矿体内及铁矿体下盘的绿帘石蚀变岩中,空间上与矿区广泛出露的闪长玢岩密切相关。对矿区闪长玢岩中锆石LA-ICP-MS U-Pb年龄及绿帘石磁铁矿矿石、黄铜矿磁铁矿矿石中辉钼矿Re-Os年龄进行了研究,闪长玢岩的206Pb/238U加权平均年龄为（377.6±1.4）Ma（MSDW=0.20）,4件样品的Re-Os同位素模式年龄为（377.7±5.9）^383.1±5.4Ma,加权平均值为（380.1±2.7）Ma（MSDW=0.66）,等时线年龄为（377.4±4.3）Ma（MSDW=0.36）,表明乔夏哈拉铁铜金矿成矿时代与闪长玢岩侵入时代一致,均为中泥盆世晚期,矿床的形成与闪长玢岩有成因关系。辉钼矿样品的w（Re）为383.1¹ 928μg/g,指示成矿物质主要来源于地幔,可能有地壳物质的加入。

Rock-forming and ore-forming ages of Qiaoxiahala Fe-Cu-Au deposit on northern margin of Junggar Basin, Xinjiang

The Qiaoxiahala Fe-Cu-Au deposit is located in the northern margin of Junggar Basin,and the ore bodies are hosted in tuffaceous sandstone,aleurolite,marble,tuff,basalt and andesite,belonging to the 3rd lithologic section of the Beitashan Formation.Iron ore bodies occur in stratoid,phacoidal or lenticular forms,while copper-gold ore bodies are hosted in iron ore bodies and epidote alterated rocks.Ore bodies are closely related to the diorite porphyrite widely exposed in the study area.Precise zircon LA-ICP-MS U-Pb dating of diorite porphyrite and Re-Os dating of molybdenite from the epidote-magnetite ore and chalcopyrite-magnetite ore were carried out in this study.The results show that the 206Pb/238U weighted average age of diorite porphyrite is(377.6±1.4) Ma(MSDW=0.20),the Re-Os model ages of four samples range from(377.7±5.9) Ma to(383.1±5.4) Ma,the weighted mean age is(380.1±2.7) Ma(MSDW=0.66),with a Re-Os isochron age of(377.4±4.3) Ma(MSDW=0.36).These data suggest that the mineralization age of the Qiaoxiahala Fe-Cu-Au deposit is similar to the intrusion age of diorite porphyrite,which took place at the end of the Middele Devonian,and that the mineralization was closely related to the intrusion of the diorite porphyrite.The rhenium content of molybdenite samples is in the range of(383.1~1 928) μg/g,which indicates that the metallogenic material was mainly derived from the mantle,probably mixed with crustal materials.