3D crustal structure of the Danxia Basin and its adjacent area in the central Nanling region revealed by receiver function imaging using a dense seismic array
The South China Block consists of the Yangtze and the Cathaysia Block that assembled in the Neoproterozoic and underwent multiple phases of intra-continental orogeny in the Phanerozoic.Detailed tectonic evolution and the controlling factors,however,are still missing largely due to the lack of a high-resolution crustal model.Over the past few decades,many geophysical surveys have imaged the deep structure in the South China Block,but with coarse resolution because of the sparse data coverage.In this study,we derive a high-resolution crustal image in the Danxia Basin and its neighboring area in northern Guangdong Province using receiver function analysis of a short-period dense seismic array.We find that the area has a relatively shallow Moho of about 28～31 km,with an average crustal thickness of 29 km.Synthetic tests show that complex 3D crustal structure,especially those associated with the low-velocity sedimentary layers,has a non-negligible effect on the study of Moho undulations.Moreover,by fitting the synthetic data to the observed high-frequency receiver functions in the Danxia Basin,we find that a low-velocity sedimentary layer of 3 km could explain the data best.The thickness is consistent with the ambient noise tomography and other geological investigations.Our experiment shows great potential for probing small-scale sedimentary basin structures using short-period dense nodal arrays.
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