Heat flow and thermal history of the South China Sea

Abstract

A total of 589 heat flow values are available from the South China Sea. The values are widely scattered, ranging from 9 to 181 mW/m 2 with a mean of 77 mW/m 2. In the northern margin, the values are less scattered and the average is about 75 mW/m 2. Heat flow increases gradually from the northern margin to the central basin, in which two high heat flow centers appear, one in the east subbasin and the other in the southwest subbasin. The southern margin has an average heat flow of 80 mW/m 2, similar to the northern margin. The western margin where the Manila trench is located has an average heat flow as low as 49 mW/m 2. In order to understand the high heat flow in the basin in the context of its tectonic history, we carried out thermal modeling using a 2D finite-element method along a profile across the northern margin. A theoretical thermal history has been inferred on the basis of a multistage pure-shear extension model. The result shows that, before Miocene, the basement heat flow showed relatively low values, ranging from 48 to 57 mW/m 2. Since Late Miocene, the basement heat flow has increased as a result of greater extension. The present-day high heat flow is primarily the result of Pliocene extension.