The Cenozoic volcanic fields in northern Hainan Island and the Leizhou Peninsula, south China: eruption history, magma source and dynamic background

Abstract

AbstractNorthern Hainan Island and the Leizhou Peninsula volcanic fields (Leiqiong), the southernmost continental Cenozoic volcanism in China, cover an area of c. 8000 km2 with 177 volcanoes recognized. Far from the subduction areas, volcanoes in this area provide an ideal opportunity to study the geodynamics of intraplate volcanoes. Here, we review the geochronological and geochemical data of the volcanic rocks in Leiqiong volcanic fields, and discuss their magma sources and geodynamics on the basis of the geological and geophysical observations. Chronological data (34.78–0.01 Ma) show that the volcanic activities started approximately in the Miocene and continued to the Quaternary. These basalts show typical geochemical characteristics of oceanic island basalts, and tomographic images reveal that a mantle plume is situated beneath Hainan Island and extends down to the core–mantle boundary. Thus, we suggest that the Hainan mantle plume is responsible for the Cenozoic volcanism in Leiqiong volcanic fields and this plume is sourced from the lower mantle with additions of dehydrated slab fragments. These mixed plume materials were brought to the upper mantle and produce solid pyroxenites, which are the major source of Leiqiong magmas. Although there is no documental record of volcanic eruptions in Leiqiong volcanic fields, the volcanic danger cannot be neglected.