Sedimentary-subsidence history and tectonic evolution of the Jiaolai basin, eastern China

Abstract：The prototype basin of the Jiaolai basin at different stages of its Cretaceous evolution and its tectonic origin have been reconstructed and determined based on the field observations of typical outcrop sections, interpretations of seismic profiles and borehole logging data and analysis of sedimentary and subsidence history of the Jiaolai basin and by following the principles and analytic methods for the study of modified and superimposed basins. The results show that the Jiaolai basin experienced three distinctive stages of sedimentation and subsidence during the Cretaceous. During the deposition of the Early Cretaceous Laiyang Group the prototype basin was mainly manifested by two NE-NNE-trending aulacogens: one developed along the Juxian-Zhucheng fault depression, and the other along the Mou-Ji fault zone. Their depocenters were controlled by the northern frontal fault zone of the Sulu orogenic belt and the Mou-Ji fault zone respectively. The deposition-subsidence rates during the stage underwent marked spatial differentiation. The maximum subsidence rates occurred along the axial zones of the aulacogens, reaching 200-350 m/Ma, and they decreased to ~60 m/Ma toward the slope zones on both sides. The Early Cretaceous Qingshan Group corresponds to a suite of intermediate-mafic to intermediate-acid volcanic rocks with a sequence of fluvio-lacustrine deposits of the Dasheng Group accumulated along the Yishu rift basin. This period was a stage of the typical continental rifting. The Jiaolai basin evolved to a volcanic basin, with a mean subsidence rate of 35-70 m/Ma. The prototype of the Late Cretaceous basin consisted of three half-grabens (i.e. the Laiyang, Gaomi and Zhucheng subbasins), whose subsidence was controlled by W-E-trending normal faults. These grabens were tectonically dextral pull-apart basins bounded on the west by the Tanlu fault and on the east by the Mou-Ji fault. During the stage the subsidence rates were relatively constant, being 63-73 m/Ma. Finally, the paper discusses the possible dynamic mechanisms in different stages of extension of this Cretaceous basin.