Early Precambrian tectonic evolution of continental craton: A case study from North China

The early tectonic evolution of craton has been the target topic for continental geology. Based on a preliminary analysis on the tectonic map (1:2000000) of North China craton (NCC) basement, we try to investigate its tectonic boundaries, structural pattern, and late stage reworking. Guided by the framework of modern plate tectonics, the NCC basement is divided into different tectonic units. It is suggested here that some key geological units (KGU), with distinct tectonic setting and geological origin, may well preserve information of its early tectonic history. With the high-precision isotopic age dating of KGU, a new timetable of geological and geochrological events has been defined for the Early Precambrian geology of NCC. In addition, several major tectonothermal episodes can be revealed by the synthesis of available age data with TTG-granite gneiss and mafic volcanics. Therefore, the Early Precambrian tectonic evolution of NCC is documented by a consideration of both regional geological research and age dating. As indicated by widespread geological research and high-precision geochronology, NCC's basement was mainly consisted of Neoarchean TTG complex and supracrustal sequences, associated with rapid crustal accretion within the setting of active continental margins and collisions between different blocks. As a result, it became stabilized at the end of the Archean. In the Early Paleoproterozoic, the NCC began to be dominated by an extensional tectonic regime, characterized by the development of early cover. In the Late Paleoproterozoic, the NCC collided with another block in the north, with formation of a supercraton, which caused a strong tectonothermal reworking to its passive margin in the northwestern part of NCC. At about 1.84 Ga, the NCC underwent extension, recorded its dispersal from a supercraton. After that, it began its tectonic evolution independently, its basement was intensely uplifted and eroded, with development of sedimentary cover. The Early Precambrian tectonic framework and geological events documented will provide an important constraint for reconstruction of the NCC within the early supercontinents.EI03285-2933