Analysis of heat flow along a transect across the South China Sea

Abstract

The western transect across the South China Sea passes from the northern margin, across the slope, and into the central deep-sea basin, extending about 900 km. Substantial but highly scattered heat flow data have been collected along this transect. Systematic analysis of these data can identify the underlying geothermal conditions and their formation mechanism. First, trend analysis is used to determine the regional heat flow. The results show a high background heat flow with an average value of about 65-70 mW/m2 in the northern part and 80 mW/m2 in the central part of the transect. The heat flow increases from the northern margin to the deep-sea region, reaches its highest value in the Central Basin, and then decreases gradually, exhibiting a typical characteristic of rifting area. Secondly, a hydrothermal circulation mechanism may explain local anomalies in the heat flow data. A numerical model study suggests that hydrothermal convection within a highly permeable horizontal layer which is linked to the surface through open faults can explain the heat flow scatter.