Stratigraphic and sedimentary records of the rift to drift evolution of the northern North China craton at the Paleo- to Mesoproterozoic transition

【摘要】：正This paper presents a stratigraphic and sedimentary study of late Paleoproterozoic to early Mesoproterozoic successions of the northern margin of the North China craton,including the Changcheng and Nankou Groups. A reconstruction of the tectono-sedimentary history of these two groups demonstrates that the northern North China craton experienced a two-stage evolution.As recorded by the Changcheng Croup,early synrift subsidence and sedimentation were controlled by normal faults and accompanied by volcanism.In contrast,a late postrift stage was characterized by broad subsidence and widespread occurrence of shallow-marine clastic and carbonate rocks.A transgressive unconformity is identified,and together with its time-equivalent conformable contact,clearly separates the synrift and postrift sequences.The diachronous unconformity can be related to continental rifting and the separation of the North China craton from the adjacent India craton at roughly 1600 Ma,and is thus interpreted as a breakup unconformity.This age of ca.1600 Mais constrained by newly reported precise SHRIMP U-Pb zircon ages of transgressive deposits in the overlying Mesoproterozoic Dahongyu and Gaoyuzhuang Formations,just coincident with the Paleoproterozoic to Mesoproterozoic transition.The 1600 Ma time estimate for the tectonic departure of the North China craton from the India craton is comparable with the timing for the breakup of Columbia,a pre-Rodinia supercontinent containing almost all of the earth's continental blocks.