Thermal-gravity equilibrium adjustment mechanism of Zhenbei-Huangyan seamount chain

During the processing of isostatic gravity anomaly analysis, it was pointed that the isostatic correction of the South China Sea was not completely, especially in Zhenbei-Huangyan seamount chain. No reasonable explanation for this phenomenon has been proposed until now, and seamounts compensation mechanism remains unresolved. It is feasible and necessary to conduct the dynamic equilibrium research in this region. We combine the thermal and gravimetric method to evaluate crustal density structure so as to establish the litho-spheric thermal structure of Zhenbei-Huangyan seamount chain based on the observed free-air gravity anomaly data. And then we analyze the thermal equilibrium and the gravity equilibrium effects based on the submarine topography data by adopting the standardized equilibrium technology. The results show that in the high heat flow region of Zhenbei-Huangyan seamount chain, the deformation induced by the thermal equilibrium is up to 0.55 km and the deformation due to the gravity is from 0.77 to 1.89 km. As a long-term adjustment factor, the thermal equilibrium constantly affects the gravity equilibrium by changing submarine topography and crustal material density， and gravity acts on geothermal equilibrium in turn at the same time， so the dynamic adjustment mechanism generates.