Abstract:

NorthSouth Tectonic Belt is an important boundary of Chinese Mainland geological structure, of deep geologic processes and of surface system, which is also an earthquakeprone zone. Yet there is little or even less research about its existence before the Mesozoic and about its tectonic feature and connection between different regions in different period. By studying the Northern NorthSouth Tectonic Belt and focusing on its central and south part, this article discusses the Carboniferous geological structure and its connection to the formation and evolution of NorthSouth Tectonic Belt which has regionalization effect. During the Carboniferous, the Northern NorthSouth Tectonic Belt was in an extensional rifting environment with intense fault activities, and it controlled the east boundary, structural pattern and thickness of Hexi CorridorNorth Qilian sedimentary domain. Its fault activities and sedimentary evolution underwent four stages: Qianheishan initial rifting period, Chouniugou further expanding period (northward), Tupo flourishing period and Taiyuan attenuating period. In the late Tupo period (Benxi) and Taiyuan period, the east (North China) and west sedimentary domain both expanded to the north part of the NorthSouth Tectonic Belt where the boundary was partly connected in its north part and later totally connected. The faults in the Carboniferous have obvious relevance to the MesoCenozoic ones in location and direction, which means that their formation and evolution was related closely. In the Carboniferous, the Northern NorthSouth Tectonic Belt and its neighborhood divided the sedimentary ranges of North China and Hexi CorridorNorth Qilian. The separationtounion evolution of sedimentary boundary, structural feature and main controlling factors showed that this zone was an important geological tectonic unit with obvious partition function in the Carboniferous, and it would have laid the foundation of further evolution of NorthSouth Tectonic Belt and of its important tectonic status.

Key words: Northern NorthSouth Tectonic Belt, South Ningxia, Carboniferous period, sedimentarytectonic evolution, geological significance