塔里木盆地夏河南玄武岩露头以水平层状分布为最大特征,其玄武岩层和沉积夹层保持了较原始的产状,是研究塔里木盆地二叠纪多期次玄武质岩浆活动的理想场所,是对比盆地内其他玄武质岩浆活动的最佳剖面.本文通过详细的野外和遥感解译工作,报道了夏河南玄武岩的野外产状、岩相学特征和各层玄武岩的地球化学特征,探讨了夏河南玄武岩的岩浆源区和岩浆演化过程.研究认为夏河南玄武岩质岩浆来源于富集的岩石圈地幔,为尖晶石-石榴石二辉橄榄岩经历低程度部分熔融的产物,各层玄武岩的成分差异与部分熔融程度有关,单一层内玄武岩的岩浆演化以分离结晶为主,地壳混染程度较小.夏河南各层玄武岩来源于同一岩浆源区,其特征与柯坪玄武岩相似,可对应于柯坪地区开派兹雷克组的6层玄武岩.研究进一步明确了塔里木盆地早二叠世玄武岩的空间分布特征,证实塔里木早二叠世大火成岩省的玄武质岩浆作用可从柯坪地区延伸到夏河南、塔中、塔西南等地.%The flood basalts from Xiahenan,Tarim Basin is mostly well-known for its horizontally layered exposure,which retains the relatively primary petrogenetic and diagenetic forms of the lavas and the intercalated sediments.It is the ideal outcrop for studying the Permian magmatism in Tarim Basin,also the best reference for other basaltic eruption events from other regions within the basin.This work introduces the field occurrence as well as lithologic and petrographic features of Xiahenan basalts based on detailed field observation and remote sensing interpretation.The geochemical characteristics of each basalt layer have been illustrated.The results show that the basaltic magma of Xiahenan were derived from an enriched lithospheric mantle,by low degree partial melting of spinelgarnet lherzolite,followed with medium degree of fractional crystallization and lesser extent of crustal contamination.The geochemical diversity among basalts within a layer is attributed to fractional crystallization,while the geochemical variations between different layers are controlled by the degree of partial melting.All the layers of basalts from Xiahenan were originated from the same mantle source,which is also similar to Keping basahs,with a good correlation to six layers of Kaipaizileike basalts from Keping region.This study further clarified the spatial distribution of the Permian flood basalts in Tarim Basin,and confirmed that the basaltic magmatism of Tarim LIP extends from Keping region to Xiahenan,as well as to central and southwest Tarim Basin.
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