Formation and exhumation of ultra-high pressure rocks through
delamination and mantle upwelling: Evidence from seismic tomographic
data beneath the Qinling-Dabie Orogen, Central China
Abstract
The Qinling-Dabie Orogenic Belt (QDOB) in Central China was built
through prolonged subduction-accretion collision events and incorporates
many exposures of exhumed ultrahigh-pressure (UHP) metamorphic rocks. We
collected a large number of teleseismic and local earthquake data and
performed a P-wave tomography and CCP stacking of receiver functions
from this region. Our results reveal high-velocity horizontal anomalies
at depths of 100-300 km beneath the QDOB, which may be related to the
deep subduction or the delamination of the lower crust and lithosphere.
We also imaged a low-velocity anomaly at depths of 200-400 km, which may
be associated with mantle upwelling in this region. Based on a detailed
analysis, we consider that the delamination of the lower crust and
lithosphere might have contributed to the formation of the UHP rocks.