Geochemistry and petrogenesis of the Cretaceous A-type granites in the Laoshan granitic complex, eastern China

摘要: Major element and trace compositions, Sr, Nd Pb isotopic compositions for postcollisional granites from the Laoshan granitic complex, in eastern side of Triassic suture between South China North tectonic blocks were determined. The are alkaline, A-type can be further classified as A1 granites. composition these is transitional those oceanic island basalt enriched mid-oceanic ridge basalt, with depletions Ba, P, Ti that ascribed to mineral fractionation enrichments Cs, Rb, Th U possibly resulted involvement slab fluids. signature represent a mixture an mantle type 1 (EMI)-like end-member lower continental crust (LCC). We propose magmas formed derived EMI-like delaminated eclogitic rocks (subsequently by fluids released Mesozoic Pacific subducted slab) LCC, which consists granulites or metamorphic residues prior generation I-type region. mixed then experienced strongly alkali feldspar-dominated their emplacements complex.