Hot lithosphere beneath the northeastern North China Craton detected by ambient noise tomography

Abstract

In this study, we present a high-resolution, 3-D S wave velocity (Vs) model of the crust and uppermost mantle beneath the Liaodong area at the northeast margin of the North China Craton (NCC). We build the model based on ambient noise tomography. Ambient noise data were obtained from both permanent stations and two new broad-band station profiles covering the Dandong-Tongliao (NCISP-10) and Baishan-Kuandian (NCISP-11) areas of the Liaodong-jilin region from October 2016 to December 2019. Our model reveals that different sides of the Tanlu Fault exhibited different Vs anomalies in both the upper crust and lithospheric upper mantle. Low Vs anomalies are observed in the west of the Tanlu Fault, which are interpreted to represent compositional variations at the crustal level. On the eastern side, low Vs anomalies are imaged which appear to represent “heat” or “hot material” derived from the deep mantle. A high Vs anomaly imaged in the southwest of the Songliao basin spatially coincides with a geologic feature referred to as the southwest uplift, which divides the basin into two secondary depressions. The Vs anomaly is inferred to represent cold mafic magma produced by the subduction of the Pacific Plate during the Late Cretaceous. Upwelling of mantle materials provide the best explanation for a mass of hot lithosphere. They underplated at the base of the crust, which formed crustal reservoirs and was eventually emplaced as plutons or erupted as volcanic rocks observed around the study area.