东天山天宇铜镍硫化物矿床磁黄铁矿Re-Os同位素物质来源示踪

发布时间：2019-03-27 13:21

【摘要】：天宇岩浆铜镍硫化物矿床的矿体由浸染状矿体和块状矿体组成。采用同位素稀释Triton-plus测定了浸染状矿石和块状矿石的磁黄铁矿Re-Os同位素比值。结果表明:浸染状矿石w(Re)为11.82×10~(-9)~45.28×10~(-9),w(Os)为0.944×10~(-9)~8.528×10~(-9),187Os/188Os初始比值为0.885~2.332,γOs为607~1763;块状矿石w(Re)为49.38×10~(-9)~315.10×10~(-9),w(Os)为0.191×10~(-9)~42.420×10~(-9),187Os/188Os初始比值为0.654~3.322,γOs为423~2555。Re、Os含量、同位素组成和特征值表明,该矿床物质为壳-幔混合来源,块状矿石可能比浸染状矿石经历了更强的地壳物质混染。浸染状矿体发育透闪石化、蛇纹石化、绿泥石化蚀变,表明存在岩浆期后热液活动,但块状矿体热液蚀变不明显,块状矿石的Re-Os同位素特征可能是与地壳岩石直接作用的结果。地壳混染作用发生在深部岩浆房,同时也发生在岩浆侵位及再次迁移过程中,这些过程造成块状矿体与浸染状矿体不同的同位素特征。
[Abstract]:The ore body of Tianyu magmatic Cu-Ni sulfide deposit is composed of disseminated orebody and massive orebody. Isotope dilution Triton-plus was used to determine the Re-Os isotope ratio of pyrrhotite in disseminated ores and massive ores. The results show that the w (Re) of leached ore is 11.82 脳 10 ~ (- 9) ~ 45.28 脳 10 ~ (- 9), w (Os) is 0.944 脳 10 ~ (- 9) ~ 8.528 脳 10 ~ (- 9), the initial ratio of 187Os/188Os is 0.885 脳 2.332, the 纬 Os is 607 脳 10 ~ (- 9); The w (Re) of massive ore is 49.38 脳 10 ~ (- 9) ~ 315.10 脳 10 ~ (- 9), w (Os) is 0.191 脳 10 ~ (- 9) ~ 42.420 脳 10 ~ (- 9), the initial ratio of 187Os/188Os is 0.654 ~ 3.322, the 纬 Os is 423 ~ 2555.ReOs. The isotopic composition and characteristic values indicate that the ore material is a crust-mantle mixing source, and the massive ore may have experienced stronger crustal material contamination than the disseminated ore. Diaphanization, serpentinization and chlorite alteration are developed in the disseminated orebodies, indicating that there is post-magmatic hydrothermal activity, but the hydrothermal alteration of massive orebodies is not obvious. The Re-Os isotope characteristics of massive ores may be the result of direct interaction with crustal rocks. Crustal contamination occurs in the deep magmatic chamber as well as in the process of magmatic emplacement and re-migration. These processes lead to different isotopic characteristics between massive orebodies and disseminated orebodies.
【作者单位】：中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室;长安大学地球科学与资源学院;中国地质科学院;新疆维吾尔自治区地质矿产勘查开发局;
【基金】：中央科研院所基本科研业务费项目(编号:K1202) 国家自然科学基金项目(编号:41203035) 地质矿产调查评价项目(编号:1212011220894-2、1212011090300)资助成果
【分类号】：P597;P618.41;P618.63

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