Petrogenesis and tectonic implications of Late Mesozoic volcanic rocks in the northern and central Great Xing'an Range, NE China: Constraints from geochronology and geochemistry

Abstract

In the northern and central Great Xing'an Range, there exist widespread Late Mesozoic volcanic rocks, of which the petrogenesis and geodynamic setting remain controversial. These rocks are composed of andesite, trachyandesite, basaltic andesite, and rhyolite. This study presents new data of zircon U–Pb dating, Hf isotopic composition, and whole‐rock geochemistry of the Late Jurassic intermediate‐mafic volcanic rocks within the northern Great Xing'an Range. In addition, the geochronological and geochemical data for the Late Mesozoic intermediate‐mafic rocks within the northern and central Great Xing'an Range are summarized for constraining the geochronological framework, petrogenesis, and geodynamic setting of the large‐scale Late Mesozoic volcanism in this region. The intermediate‐mafic volcanic rocks are enriched in large‐ion lithophiles and light rare earth elements and are depleted in high‐field‐strength elements such as Nb, Ta, and Ti, with positive εHf(t) values (+0.7 to +15.4). The data indicate that the volcanic rocks were derived from the partial melting of a mantle wedge that was modified by previously subducted slab‐derived fluids. These Late Mesozoic intermediate‐mafic volcanic rocks record a post‐collisional lithospheric extensional setting resulting from the closure of the Mongol‐Okhotsk Ocean.