Early Cretaceous arc-related volcanic rocks in the northern Great Xing'an Range, NE China: records of Paleo-Pacific ocean subduction

There are widespread Late Mesozoic volcanic rocks in the Great Xing'an Range, Northeast China. However, the precise age data and tectonic evolution are still controversial. In this paper, a suite of intermediate-felsic volcanic rocks and mafic volcanic rocks have been recognized in the Daheishan of the northern Great Xing'an Range. Zircon U-Pb dating constrains two groups of the crystallization ages at 129 Ma (dacite) and 124-127 Ma (rhyolite, rhyodacite and andesite), respectively. They all have magmatic zircon geochemical characteristics, including systematic positive Ce anomalies, weak negative Eu anomalies, and high Th/U ratios (average 0.84). The intermediate-felsic volcanic rocks show crustal signatures with high K2O (1.91-7.57 wt% and low MgO (0.19-2.78 wt%) contents. The zircon epsilon(Hf)(t) values mostly range from + 4.7 to + 10.2, with dominant two-stage model ages (T-DM2) of 530-878 Ma. Therefore, combined with previous data, the mantle-derived mafic melts may have triggered partial melting of the juvenile lower crust to produce intermediate-felsic magmas, and the source rock is considered to be an amphibolite. In addition, the trace element data of the volcanic rocks display arc-like signatures. The published and our geochronological data indicate that these Late Mesozoic volcanic rocks in the Great Xing'an Range were mainly formed in the Early Cretaceous with a peak range of 124-133 Ma. The large-scale Early Cretaceous volcanic rocks in the Great Xing'an Range were formed in an active continental margin setting related to the subduction of the Paleo-Pacific Ocean.

Automated summary

This study investigates the volcanic rocks in the northern Great Xing'an Range, identifying a suite of late Mesozoic volcanic rocks. Zircon U-Pb dating reveals that these rocks were primarily formed in the Early Cretaceous, potentially triggered by mantle-derived mafic melts inducing partial melting of the lower crust to produce intermediate-felsic magmas.