Characteristics and tectonic setting of Late Cretaceous volcanic magmatism in the coastal Southeast China
东南沿海晚白垩世火山岩浆活动特征及其构造背景

Late Cretaceous volcanic magmatisms in the coastal Southeast China are weak and lack enough studies, but have significant tectonic implications. This paper reports studies on Late Cretaceous Xiaoxiong Formation and Shiniushan Formation volcanic rocks and associated plutonic rocks in Zhejiang and Fujian provinces. Zircon ages of both central intrusion facies syenite-porphyry at Xiaoxiong caldera and syenogranite-porphyry at Shiniushan caldera are 87.9±1.2Ma and 93.8±1.3Ma respectively. Based on their petrological and geochemistric features, these rocks are proved to be post-orogenic A-type granitoids. They were generated during intenser extension of lithosphere after formation of the huge Cretaceous A-type granite belt in the coastal Southeast China, and belong to the latest felsic magmatism in Mesozoic. It is inferred that the Yanshanian orogeny ended at ca. 90Ma.