新疆图拉尔根镁铁-超镁铁质杂岩体镍铜钴成矿岩浆作用过程:流体化学与碳同位素组成制约  

The magmatic process of Cu-Ni-Co sulfide ore-forming in the Tulaergen mafic-ultramafic complex,Xinjiang,northwestern China:Constrains from chemical and carbon isotopic compositions of volatiles

作　　者：张铭杰 班舒悦 李思奥 宋哲 仇哲 李立武 惠卫东 李中平 ZHANG MingJie;BAN ShuYue;LI SiAo;SONG Zhe;QIU Zhe;LI LiWu;HUI WeiDong;LI ZhongPing(Gansu Key Laboratory of Mineral Resources in Western China,School of Earth Sciences,Lanzhou University,Lanzhou 730000,China;Key Laboratory of Petroleum Resources(Gansu Province),Northwest Institute of Eco-Environment and Resources,CAS,Lanzhou 730000,China;Hexing Mining Corporation,Hami 839000,China)

机构地区：[1]兰州大学地质科学与矿产资源学院甘肃省西部矿产资源重点实验室,兰州730000 [2]中国科学院西北生态环境资源研究院甘肃省油气资源研究重点实验室,兰州730000 [3]新疆哈密和鑫矿业有限公司,哈密839000

出　　处：《岩石学报》2020年第12期3673-3682,共10页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(91962212、41872075、41372095)资助。

摘　　要：东天山造山带的图拉尔根镁铁-超镁铁杂岩体为一个早古生代长期活动的幔源岩浆通道,大型铜镍钴硫化物矿体赋存于Ⅰ号超镁铁质岩体的顶部,不同类型岩石中辉石矿物的流体挥发份化学组成以H2O为主(平均91%,5400.4mm3/g),其次为H2(2.0%)、H2S(2.3%)和CO2(2.1%);赋矿角闪橄榄岩中CO2和H2S含量最高,辉长岩中流体挥发份含量低于辉石橄榄岩和橄榄辉石岩等岩浆早期结晶的岩石。CO2和CH4的δ13C值位于地壳与甲烷氧化的范围内,甲烷同系物的碳同位素组成具有正序分布模式,部分样品(TLG512)释出的CH4和C2H6具有较重的δ13C值和反序分布特征。表明I号岩体不同类型岩石可能是不同期次岩浆活动的产物,成矿岩浆具有富H2O和H2S的特征,可能起源于被流体交代的亏损地幔源区,混染壳源组分可能为俯冲板片来源蚀变沉积有机质组分。The Tulargen mafia-ultramafic complex(ca.357~300 Ma)at the eastern end of the Paleozoic mafia-ultramafic belt in the Eastern Tianshan Orogen Belt,northwestern China is an Early Paleozoic long-lived mantle-derived magma conduit.A large Cu-NiCo sulfide deposit occurred at the top of No.Ⅰultramafic intrusion.The chemical composition and carbon isotope composition of volatiles in pyroxene mineral of different types of rocks in No.Ⅰultramafic intrusion have been studied,the results indicate that the chemical composition of volatiles is predominated by H2 O(average 91%,5400.4 mm3/g),followed by H2(2.0%),H2 S(2.3%)and CO2(2.1%).The ore-hosted amphibole peridotite shows the highest contents of CO2 and H2 S.The volatile contents of gabbro are lower than those of pyroxene peridotite and olivine websterite etc.rocks crystallized at early magma stage.Theδ13 C values of CO2 and CH4 ranged into crust and methane oxidation.The carbon isotopic composition of methane homologue display normal distribution pattern with carbon number;the CH4 and C2H6 released at 900~1200℃from Sample TLG512 have heavyδ13 C values and a reversal distribution pattern.All above indicate that different types of rocks of No.Ⅰultramafic intrusion may be the products of different periods of magma.The magma could be rich in H2 O and H2 S,and originated from the depleted mantle source metasomatized by slabderived fluids during the closure of the ancient Tianshan Ocean.The large proportion of contaminated crustal components could be the fluid component from alterated sedimentary by subducted slab in magma source.

关 键 词：岩浆过程 碳同位素组成 流体挥发份 图拉尔根镁铁-超镁铁质杂岩体 东天山造山带 

分 类 号：P611[天文地球—矿床学]