塔里木大火成岩省瓦吉里塔格层状岩体的钼同位素组成特征及其地质意义  

Molybdenum Isotope Characteristics of the Wajilitag Layered Intrusion in the Tarim Large Igneous Province and Their Geological Significance

作　　者：曹俊 王旋 陶继华[1,2] CAO Jun;WANG Xuan;TAO Ji-hua(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013, China;School of Earth Sciences,East China University of Technology,Nanchang 330013,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]东华理工大学地球科学学院,江西南昌330013

出　　处：《东华理工大学学报（自然科学版）》2020年第2期128-136,共9页Journal of East China University of Technology(Natural Science)

基　　金：国家自然科学基金项目(41703030);国家留学基金委项目(201808360273);江西省青年科学基金项目(20192BAB213024);山东省沉积成矿作用与沉积矿产重点实验室开放基金(DMSM20190029)。

摘　　要：钼同位素地球化学是国际地学研究领域的一个前沿和热点问题。塔里木大火成岩省中的瓦吉里塔格镁铁质超镁铁质层状岩体的Mo同位素研究结果表明,瓦吉里塔格镁铁质超镁铁质岩石具有相近的Mo同位素组成,其平均值为-0.18‰±0.04‰(2 s.d.;n=11)。在瓦吉里塔格岩浆体系中,岩浆分异没有导致明显的Mo同位素分馏。瓦吉里塔格岩石中Mo同位素与其(87Sr/86Sr)i和εNd(t)值呈现一定相关性,指示其地幔源区不均一性。此外,这些岩石δ98Mo值低于洋中脊玄武岩δ98Mo值范围(^-0.15‰),指示它们的源区很可能受到早中古生代南天山洋板片俯冲的熔体交代的影响。结合前人研究成果,塔里木大火成岩省中丰富的岩石系列可归因于不均一的地幔源区以及地幔柱岩石圈俯冲洋壳的相互作用。Molybdenum(Mo)isotope geochemistry is becoming a new frontier and hot issue in earth sciences.Our results show all the mafic ultramafic rocks from the Wajilitag layered intrusion in the Tarim Large Igneous province had nearly identical Mo isotopic compositions with an averageδ98Mo of-0.18‰±0.04‰(2 s.d.;n=11).There is no significant Mo isotope fractionation during magmatic differentiation at Wajilitag.There is a positive correlation between(87Sr/86Sr)i andδ98Mo and negative correlation betweenεNd(t)andδ98Mo in these rocks,reflecting the derivation from the heterogeneous mantle sources.Furthermore,the Wajilitag rocks yieldδ98Mo values are lower than that of MORBs(-0.15‰),which suggests that the mantle may have been affected by the Early-Middle Paleozoic subducted South Tianshan oceanic slab-derived melts.In combination with previous studies,we propose that the abundant lithologies of the Tarim Large Igneous province could be possibly attributed to the mantle source heterogeneity and Tarim mantle plume lithosphere subducted oceanic slab interactions.

关 键 词：瓦吉里塔格 层状岩体 MO同位素 源区不均一性 塔里木大火成岩省 

分 类 号：P619[天文地球—矿床学]