Geochronology, geochemistry, and Sr-Nd isotopes of Early Carboniferous magmatism in southern West Junggar, northwestern China: Implications for Junggar oceanic plate subduction

West Junggar is a key area for understanding intra-oceanic plate subduction and the final closure of Ocean. Knowledge Carboniferous tectonic evolution Ocean region required framework accretionary processes in Junggar, Central Asian Orogenic Belt. A series Early volcanic intrusive rocks, namely, basaltic andesite, dacite, diorite, occur Mayile southern northwestern China. Our new LA-ICPMS zircon U-Pb geochronological data reveal that diorite intruded at 334 (±1) Ma, andesite was erupted (±4) Ma. These rocks are calc-alkaline, display moderate MgO (1.62%–4.18%) contents Mg# values (40–59), low Cr (14.5×10−6–47.2×10−6) Ni (7.5×10−6–34.6×10−6) contents, characterized by enrichment light rare-earth elements large-ion lithophile depletion heavy high-field-strength elements, meaning they belong to typical subduction-zone island-arc magma. The samples show initial 87Sr/86Sr ratios (range 0.703649–0.705008), positive εNd(t) 4.8–6.2 mean 5.4), young TDM Nd model ages ranging from 1016 616 indicating magmatic origin depleted mantle involving partial melting 10%–25% garnet spinel lherzolite. Combining our results with those previous studies, we suggest these were formed as result northwestward oceanic plate, which caused sub-arc mantle. We conclude arc magmatism extensive during Carboniferous.