Thermal history and tectonic-thermal evolution of Bohai Basin, East China

Heat flow measurements and thermal history reconstruction, from inversion o f apatite and vitrinite reflectance data, indicate that Bohai Basin is char acterized by lower present-day heat flow varying between 50 and 75mW / m(2) with a background heat flow value of 63.6mW / m(2), and that the basin exp erienced a much higher heat flow (70-90mW / m(2)) period prior to about 25M a. Structural subsidence analysis shows that the subsidence of Bohai Basin, consisted of East Liao Bay and Bohai areas, can be divided into two phases : earlier(25-50Ma) initial (rift) and later (since 25Ma) thermal subsidence . The earlier rift phase is composed of two sub-rift episodes with quick su bsidence, and the later thermal subsidence was superimposed with rapid subs idence related to crustal isostasy induced by higher density mantle and coo ling of the lithosphere. The lower present-day heat flow and the higher pal aeo-heat flow corresponding to structural subsidence stage as well as the t ypical rift subsidence style in Bohai Basin support its feature of intrapla te, rift basin, and provided with some insight to the tectonic-thermal evol ution of the basin.