摘要
金川铜镍硫化物矿床及其与附近的镁铁-超镁铁质岩体的成因关系对成岩成矿理论研究及找矿具有重要意义。通过对镁铁-超镁铁质岩体的岩石学、年代学、岩石地球化学、同位素地球化学研究,获得金川附近的茅草泉镁铁-超镁铁质岩体中单颗粒锆石U-Pb年龄为(832.5±1.5)Ma,与金川超镁铁质岩体中锆石U-Pb年龄(831.8±0.6)Ma在误差范围内一致。岩石地球化学数据显示,金川岩体与茅草泉岩体都属于亚碱性拉斑玄武岩系列,微量及稀土元素配分曲线平行,变化趋势相似,属于右倾型,具有Nb、Ta负异常;Cu/Zr比值显示过渡变化特征,Cu/Ni比值都小于1,原始地幔标准化的铂族元素配分曲线平行过渡。同位素地球化学数据显示,样品具有高正εSr(t)值,低的εNd(t)值,较低的206Pb/204Pb值,指示岩浆源区为EMⅠ型富集岩石圈地幔。多种方法证明了金川、茅草泉岩体具有同期同源岩浆演化特征,茅草泉小岩体群可能是金川母岩浆先期侵入岩相,为金川矿床的形成贡献了亲铁元素与橄榄石成分。
The genetic relationship between the Jinchuan Cu-Ni sulfide deposit and the near-by mafic-ultramafic intrusions is important for further exploration. The zircon U-Pb age （832.5 ± 1.5） Ma of the Maocaoqun mafic intrusion is consistent with the zircon U-Pb age （831.8 ± 0.6） Ma of the Jinchuan ultramafic intrusion. Petrogeochemical compositions indicate that both intrusions belong to sub-alkaline tholeiitic basalts, and chondrite-norrealized REE and primitive-mantle normalized micro-elements diagrams show parallel patterns, displaying LREE enrichment and Nb, Ta negative anomalies. Primitive-mantle normalized PGE patterns show parallel distribution between Maocaoqun and Jinchuan ultramafic intrusions. Isotopic geochemical data display high esr（t）, low end（ t ） and fairly low ^206pb/^204pb values for both intrusions, which implies that the magma forming the intrusions came from the enrichment mantle source like EM I -type mantle. The above features suggest that the
出处
《矿床地质》
CAS
CSCD
北大核心
2012年第6期1135-1148,共14页
Mineral Deposits
基金
国家自然科学基金项目"甘肃龙首山地区与铜镍成矿有关的幔源岩浆事件重建"(编号:41072058)
公益性行业科研专项(编号:200911007
201011058)
长安大学科技创新研究项目(编号:CHD2010ZD005
CHD2011TD007)的联合资助
