Cenozoic thermal history of the Bohai Bay Basin: constraints from heat flow and coupled basin-mountain modeling

摘要

Heat flow measurement show a moderate thermal background (～16 mW/m~2) in the Bohai Bay Basin, which although experienced multi-phase rifting in the Cenozoic era. In contrast, its surrounding mountain areas are characterized by low heat flow. Constraint by heat flow measurements, the thermal evolution of the Bohai Bay Basin during the Cenozoic era was performed by a numerical basin-mountain model. The model incorporates differential lithosphere stretching and shortening by finite-element method in the Lagrangian frame. The predicted heat flow in the center of the three depressions of the Bohai Bay Basis is calculated to have varied between 51 and 63 mW/M~2 through the Cenozoic evolution, indicating a rather smooth variation of basin thermal state, and a cooling trend from the Oligocene to present-day. Model results also suggest that the Taihang mountains probably uplifted in the Quaternary, which resulted in low heat flow in the mountain area. Both heat flow constraints and modeling imply that a new phase of rifting in the Pliocene existed in the Huanghua and Bozhong Depressions, witch was suggested by tectonic subsidence analysis.