Discussion and analysis of superimposed sedi-mentary basins

Abstract

The Chinese Continent is situated in the transitional tectonic domain between the Siberian and Gondwana Continent. It had been controlled sequentially by the Paleo-Asian Ocean dynamic system, the Tethys and Paleo-Pacific dynamic system, and the India Ocean and the Pacific Ocean dynamic system since the Sinian Period. Its mainland is composed of small continental blocks such as the North China, the Yangtze, the South China, and Tarim blocks etc. as well as so many micro-continental blocks, which are located in several large-scale orogenic belts. The sedimentary basins developed on the base of or at the margin of the mentioned above continental blocks is mostly of superimposed basins. The superimposed basin has been resulted either from the composition of proto-type basin during the same stage and the superimposition of proto-type basin of different stages. It has undergone drastic periods of tectonic trans-formation during the different dynamic system stages. The two mega cycles, one of which began with the break-up of Rodinia Continent since the Late Proterozoic and ended with the formation of the Pangea in the Triassic, and the other began with the break-up of the Pangea in the Jurassic Period and ended with the convergence of discrete plates, has accordingly resulted in different types of superimposed basin before or after the Triassic in China. Because of the sub-cycles of extension and compression during each mega cycle, the extension and the compression system or the strike-slip system transformed each other frequently, which induced the multiple periods of drastic tectonic transformation, leading to the multiple superimposition of the proto-type basins. The Chinese sedimentary basins are characterized by the poly-history superimposed basins with a character of distinctive oil and gas accumulation and distribution.