Analysis of tectonic subsidence and heat flow in the Malay Basin (offshore Peninsular Malaysia)

Abstract

The Malay Basin has a very high present-day surface heat flow, with an estimated heat flow anomaly of about 33-42 m W m-2 • The heat flow anomaly is interpreted as the result of thinning of the lithosphere during basin formation. The basin is relatively young age (about 35 Ma), which implies that the thermal anomaly due to lithospheric thinning has not dissipated completely; the Basin is still undergoing thermal subsidence. Data from over 60 wells were used in the analysis of subsidence and thermal histories to gain a better understanding of its tectonic evolution. A model of lithospheric stretching was used, whereby rifting occurred over a 10 Ma year period starting 35 Ma ago. The subsidence histories from well data gave stretching factor (13) estimates ranging from about 1.2 on the basin flanks to about 4 in the centre. The basin flanks were uplifted during the initial rifting, causing subsidence to be delayed for about 10 Ma. Flank uplift was probably the result of non-uniform stretching of the lithosphere and horizontal heat loss through the sides of the basin as the lithosphere was being stretched. Heat flows calculated using the 13 estimates agree with those derived from well test data and, therefore, supports the stretching model. These results are comparable with those derived from maturity mode~g using available vitrinite maturity data.