Isostatic Anomaly and Vertical Tectonic Stress Analysis by Gravity Observations in Qinling Area

  Objectives  It is important to determine the isostasy anomaly and the vertical tectonic stress for understanding the deep tectonic features and dynamics in Qinling area. At present, high-precision observation gravity data is one of the important means to obtain the isostasy anomaly and the vertical tectonic stress.

  Methods  The free-air gravity anomaly and the Bouguer gravity anomaly are computed by using gravity and GPS data, and the isostasy anomaly and the vertical tectonic stress are further inferred.

  Results  The results show that the isostasy depth is 40-49 km, the Moho depth is 39-48 km and the vertical tectonic stress carried by the crust is -28-24 MPa.

  Conclusions  The Weihe Basin on the northern of Qinling area is in a non-isostatic state. The isostasy anomaly and the vertical tectonic stress are approximately zero in the Northern Sichuan Basin, which indicates the basin is in an isostatic state. The local negative isostasy anomaly in Qinling indicates that there is existence crustal movement.