关键词: 原型盆地, 张扭断陷, 裂谷盆地, 盆地反转, 盆地叠加, 生烃洼陷叠置

Abstract: Two periods of rifting basins had developed in the Ejinaqi region since the Jurassic. The study area was in a tectonic setting of transtension during Early and Middle Jurassic, and the basins were reversed and uplifted in Late Jurassic. The basin evolution from the Cretaceous to the Palaeogene shows a complete process of rifting development, in which the Lower Cretaceous is the product of early rifting and the Upper Cretaceous and the Eogene represent the sediments of thermal subsidence in late rifting stage. The Jurassic and Cretaceous basins belong to two different types of basin. The superimposition styles of the two types of basins controlled the source rock development and have an impact on the hydrocarbon potential in this region. The source rocks in the Lower and Middle Jurassic are good and better than those in the Lower Cretaceous. The hydrocarbon-generation potential of depressions was determined by the scale and superimposition of two hydrocarbon-generation sags. Tiancao depression is the most perspective area where the sag developed successively and the Lower-Middle Jurassic and the Lower Cretaceous source rocks have a good superimposition.

Key words: Proto-basin, transtensional faulting, rifting basin, basin inversion, basin superimposition, hydrocarbon-generation sag superimposition