| In this paper, the as well as their influence on hydrocarbon accumulating are discussed after research of plate structure, structural dynamics/geometric, palaeogeothermal, tectonic subsidence history and basin evolution history here by multidisciplinary analysis.The main achievements and innovations in this paper are as follows: 1. After analyzing plate structure background in which Bohai bay basin formed and inner structure features of Tanlu fault, it is put forward that Bohai bay basin is an active-type rift basin. Meanwhile, the structural evolution of Jiyang-Changwei depression since Mesozoic-Cenozoic is divided into five stages as residual basin, NW rift basin, EW rift basin, right-lateral slip tensional-fault basin and post-rift thermal subsidence.2. Through analogy analysis between Jiyang depression and the basin group in southwest Shandong Province, it is concluded that the prototype basins of the latter can be classified into two types: NW basins which are formed earlier as the result of left-lateral slip of Tanlu fault and EW basins which are formed relatively later as the result of right-lateral slipof Tanlu fault. Structure transformation and the sedimentation of Zhujiagou formation in southwest Shandong are well-matched in age (50Ma). This achievement also can confirm the evolution history and dynamic background of Jiyang-Changwei prototype basin.3. Through analyzing the distribution characteristics and geochemical behaviors (such as macroelement, rare earth element and microelement) of volcanic rock here, structural transformation characteristics of Jiyang-Changwei depression in Cenozoic are studied using new geochemical theories and principles. Several transformation stages can be identified as follows: between Mesozoic and Cenozoic;between EK and ES;between third member and second member of ES;between ED and NG.4. Prototype basins in this area can be classified into two kinds: Yingxiongtan and Guxi sag controlled by Guxi fault, Yong'an sag controlled by Minfeng-Guangli fault and Boxing sag controlled by Shicun fault belong to the earlier NW basins;Huimin sag, Linfanjia sag, Dongying sag, Chexi sag, Weibei sag and Houzhen sag belong to the later EW basins. The structural transformation age from NW basins to EW basins is determined to be between the upper part and lower part of EK2 (50Ma).5. The evolution history of prototype basins in Dongying sag and Huimin sag is simulated through forward modeling of balancedcross-section of extensional fault propagation folds using correlated theories. And a new method is developed to describe and interpret the geometric characteristics and structural history of asymmetric semi-graben in rift basins.6. The subsidence rates of different evolution stages are determined through analyzing subsidence history of four sags (Dongying sag, Zhanhua sag, Huimin sag and Linfanjia sag) in Jiyang depression using log and seismic data.7. Palaeogeothermal and its gradient in this basin are studied through analyzing systematically the characteristics of clay minerals in Jiyang-Changwei depression. From crystallinity of authigenic illite in Es4-Ek strata here, palaeogeothermal gradient in Jiyang depression is determined to be 3.82 ~ 3.92°C/100m and that in Changwei depression is 3.69°C/100m. From chemical compositions of chlorite here, the palaeogeothermal gradient should be 3.80 ~ 3.91°C/100m also. After palaeogeothermal studies, it is concluded that the oil threshold in Jiyang depression is 1700 ~ 4000m and that in Changwei depression is 1700 ~ 4000m (maybe below 3800m in local area).
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