叠合盆地概念辨析

Discussion and analysis of superimposed sedi-mentary basins

中国大陆地处西伯利亚与冈瓦纳大陆之间的转换构造域,在地质历史上依次受古亚洲洋、特提斯—古太平洋与印度洋—太平洋三大动力体系的控制,其主体由包容在几个巨型造山带之间的华北、扬子、华南、塔里木等小陆块及众多的微陆块拼合而成。发育在这些陆块之上及其边缘的沉积盆地多为叠合盆地,即由同一阶段的原型盆地发生复合、不同阶段的原型盆地相叠加的盆地类型,经历了多个阶段运动体制(包括构造体制与热体制)的变革。新元古代Rodinia古陆解体至三叠纪Pangaea泛大陆形成过程以及侏罗纪以来Pangaea大陆裂解与聚敛过程构成全球的两个构造巨旋回,在中国境内形成了以三叠纪为界的不同叠合盆地类型。在每一巨旋回内部还发育次一级的开 合旋回,多个伸展体制与挤压体制或走滑体制的相互转换期成为盆地的多个关键构造变革时期,从而导致原型盆地多次叠合。多旋回叠合盆地是我国沉积盆地的主要特色,具有独特的油气聚集与分布规律。

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.