Genesis and Tectonic Environment of Basalts in Balikuntage, Xinjiang:Implications from Geochemistry and Sr-Nd-Pb Isotopes

The volcanic rocks from the Liushugou formation are widely distributed in Balikuntage area, Xinjiang. Study on the basalt, their petrology, geochemistry and isotope geochemistry indicate that, the basalts in this area belong to tholeiite series and are characterized by LREE, LILE(Sr, K, Rb, Ba, Th) enrichments and HFSE(Nb, Ta, Ti), HREE depletion, low Sr-Nd-Pb isotope(⁸⁷Sr/⁸⁶Sr)t=0.70382-0.70667;(²⁰⁶Pb/²⁰⁴Pb)t=17.857-18.054; (²⁰⁷Pb/²⁰⁴Pb)t=15.494-15.545; (²⁰⁸Pb/²⁰⁴Pb)t=37.746-37.798 and high _εNd(_εNd_(t)=+4-+8.3), which show its depleted mantle origin and contamination of crust materials. Through comparing with the basalts of the eastern Bogda in the same period, the results show that Balikuntage has the similar structure attributes with the Bogda area, which is the continental rifting in the late Carboniferous. But they belong to different stages of rifting evolution, thus, their geochemistry exhibits some disparities.