Origin of intraplate volcanism in northeast China from Love wave constraints

The tectonic source for widespread volcanism in northeast China has not been completely understood. We develop a 3-D SH velocity model in NE China that provides new constraints to the origin of the volcanism. The 3-D model is constructed from fundamental mode Love waves at the periods of 20-125 s recorded at 269 broadband seismic stations. The Changbai Mountain is characterized by a significant low velocity in the lower crust and uppermost mantle, which probably results from mantle upwelling due to the subduction of the Pacific plate. A fast and thin mantle lid of similar to 75 km is present beneath the Songliao Basin, indicating lithosphere extension from back-arc rifting. The slow velocity in the middle and fast velocities in the south and north at 75-115 km depths in the Songliao Basin suggest complex mantle flow with upwelling and downwelling. Unlike the other volcanic fields (Changbaishan volcano, Jingpohu volcano, and Abaga volcano), the Halaha volcano has high velocity in the lower crust and upper mantle, implying a limited melt supply from mantle source recently. The subduction-induced upwelling leads to complicated small-scale mantle convection, which is responsible for the intraplate magmatism in northeast China.