Identification of the volcanic edifice in continental volcanic areas: A case study of the Dongming resurgent caldera in Xinchang, Zhejiang Province

The identification and anatomy of volcanic edifice is the key of continental volcanic mapping.Taking the Dongming resurgent caldera in Cretaceous Xinchang basin of Zhejiang Province as an example, the investigation method of volcanic edifice in continental volcanic area is discussed.The caldera is centered on the Zhushan-Guozhan-Dajiangang volcanic channel, and the inward-dipping volcano-sedimentary strata are cut by annular and radial faults, with developed dikes.Based on the comprehensive applications of remote sensing interpretation, geophysics, geochemistry and regional geological survey, the types, forms and ranges of volcanic edifice, characteristics of eruptive products and their spatial and temporal distribution patterns have been identified, which can be used as an important means to recover the history of volcanic eruptions and determine the evolution of volcanic edifice.The evolutional history of Dongming resurgent caldera can be divided into four stages: normal sedimentation accompanied with small eruption, major eruption, crater collapse and resurgence.The results show that the determination of volcanic vent, volcanic lithofacies and lithology, the distribution and spatial-temporal variations of eruptive products and ring faults are the key factors to identify the volcanic edifice and recover the volcanic history.