Simulation of gravity anomaly of the velocity profile from wide-angle reflection seismic profiling and the granite belt in the Dabie Mountains

Abstract： Simulation of gravity anomaly at the Liu’an-Daye wide-angle reflection profile transecting the Dabie orogenic belt shows that the gravity anomaly produced by the density profile obtained by conversion of the seismic velocity from wide-angle reflections is a gravity high, which reflects that the Dabie Mountains area is a dome. This result is quite different from a gravity low determined by the field gravity measurements. The gravity anomaly can be well simulated only by placing a huge low-density body from the surface to the Moho at the boundary between the North and the South Dabie Mountains, at the root of the Dabie Mountains. This low-density should be a nearly NW-trending granite belt. Its location is in good agreement with that of the Shizhen transparent seismic reflection belt but it is far wider than the latter. The fitting of the gravity curve further suggests that after collision between the North China block and Yangtze block an extensional period occurred in the Dabie area during the Cretaceous, and meanwhile, the Dabie dome formed, accompanied by extensive intrusion of granite, and ultrahigh-pressure metamorphic rocks were exhumed to the surface. This study shows that it is necessary to combine seismic reflection profiling, wide-angle seismic reflection profiling and gravity survey to make an integrated interpretation.