Early Jurassic A-Type Granites in Southeast China: Shallow Dehydration Melting of Early Paleozoic Granitoids by Basaltic Magma Intraplating
AbstractA-type granites are widespread in most orogenic belts, and their petrogenesis has played an important role in reconstructing orogenic events. However, their sources, even today, are a subject of considerable controversy. At least four models have been proposed for their formation, namely, melting of a previously melted source, fractionation of basaltic magma, anatexis of crustal igneous sources, and magma mixing. Here we present Early Jurassic A-type granites in southeast (SE) China as an example of a shallow (ca. 15–20-km depth), igneous, crust-derived A-type granite. We present detailed laser ablation ICP-MS zircon U-Pb dating and major- and trace-element and Sr-Nd isotopic data for these granites and assess their origin and relationship to the geodynamics of the late Mesozoic extensive magmatism in SE China. The associated granites include the Zhaibei, Keshubei, Zhulanbu, and Guangze plutons, which were emplaced during the interval 191–188 Ma and occur in a northeast-trending belt, parallel to ...