Thermal history and tectonic subsidence of the Bohai Basin, northern China: a Cenozoic rifted and local pull-apart basin

The Bohai Basin is a part of the larger Bohai Bay Basin, a Cenozoic rifted intraplate basin. Heat flow measurements show that the Bohai Basin is chara cterized by present-day heat flow varying between 53 and 74 mW/m(2) with a mean of 63 mW/m(2). However, thermal history analyses derived from vitrinit e reflectance (VR) and apatite fission track (AFT) data, indicate that tert iary cooling took place following a period of much higher paleo-heat flow ( 70-90 mW/m(2)) prior to similar to 25 million years to the present. Further more, tectonic subsidence analysis reveals that the Bohai Basin experienced episodic sub-rifting processes from the Eocene to the end of the Oligocene . The post-rift thermal subsidence was superimposed by intensified subsiden ce from the late Miocene (12 million years) in the Bozhong Depression and f rom the early Quaternary (2.4 million years) in the East Liao Bay, indicati ng a rejuvenation of sedimentation related likely to transpressional struct ures developed locally on strike-slip faults. The present results indicate that there is good agreement between the reconstructed thermal history and the timing of the tectonic subsidence stages within the Bohai Basin. The Bo hai Basin is an early Cenozoic rifted and local pull-apart sub-basin of the larger Bohai Bay Basin. (C) 2001 Elsevier Science B.V. All rights reserved .