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

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 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

The Tulargen mafia-ultramafic complex (ca. 357~300Ma) 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-Ni-Co sulfide deposit occurred at the top of No.Ⅰ ultramafic intrusion. The chemical composition and carbon isotope composition of volatiles in pyroxene mineral of different types of rocks in No.Ⅰ ultramafic intrusion have been studied, the results indicate that the chemical composition of volatiles is predominated by H2O (average 91%, 5400.4mm3/g), followed by H2 (2.0%), H2S (2.3%) and CO2 (2.1%). The ore-hosted amphibole peridotite shows the highest contents of CO2 and H2S. The volatile contents of gabbro are lower than those of pyroxene peridotite and olivine websterite etc. rocks crystallized at early magma stage. The δ13C 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 heavy δ13C values and a reversal distribution pattern. All above indicate that different types of rocks of No.Ⅰ ultramafic intrusion may be the products of different periods of magma. The magma could be rich in H2O and H2S, and originated from the depleted mantle source metasomatized by slab-derived 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.