Heterogeneous Tarim Cratonic Crust Induced by a Mantle Plume and Its Effect on Later Tectonic Evolution Based on Multi-Frequency Receiver Functions Imaging

Abstract

It remains controversial whether the interaction between a mantle plume and a craton destabilizes or reinforces the craton. The Tarim basin, with a craton core, a Permian Large Igneous Province, and internal deformation, is an ideal place to investigate this interaction. Here, we construct high-resolution S-wave velocity structures down to 15 km in depth using multi-frequency receiver functions from two temporary seismic arrays that largely cover the Tarim Basin. Our results reveal a strong velocity-increasing discontinuity across the basin and several large-scale high-Vs anomalies. The discontinuity is flat at about 3.5 km depth in the majority of eastern Basin but is uplifted and folded to ∼3 km depth around the Bachu Uplift in the central-western basin and depressed to more than 6 km depth in the northwestern and southwestern basin. The high-Vs anomalies, with an average Vs of ∼3.4 km/s, are concentrated under this discontinuity around the Bachu Uplift. Analysis with drilling data, experimental rock-physics data and previous geophysical observations indicates that the discontinuity corresponds to the top of early Permian strata, and the high-Vs anomalies are the magmatic intrusions from the early Permian mantle plume. There is strong deformation around the Bachu Uplift formed during Cenozoic Indian-Eurasian collision, exhibiting a strong spatial correlation with the Permian magmatic intrusions. This suggests that the western Tarim Craton, compared to the east, may be weakened in strength by the Permian mantle plume and exhibits more localized Cenozoic deformation.