超级克拉通盆地发育的构造背景及其形成模式探讨

克拉通盆地是所有盆地类型中最稳定、最长寿的盆地,也是地壳和地幔长期垂向变形最重要的地质记录。地史上面积最大的克拉通盆地(超级克拉通盆地)原型面积常超过200×10^4 km^2,对探讨克拉通盆地成因演化具有重要的代表性意义。目前世界各地的研究可以识别出10余个不同时期的超级克拉通盆地。本文根据超级克拉通盆地基底性质、盆地发育的超大陆构造演化背景及其构造特征,将超级克拉通盆地划分为A型盆地和B型盆地两种类型,它们分别以西西伯利亚盆地和刚果盆地为代表。A型盆地形成于超大陆裂解之前至初始裂解的背景下,基底为前期造山带,为短波长盆地。盆地形态不规则性强,内部均一性相对较低,克拉通盆地边缘可能渐变为弧后盆地或前陆盆地。B型盆地形成于超大陆裂解末期(即下一个超大陆汇聚之初),基底为古克拉通陆块,为长波长盆地,盆地多呈对称的宽缓碟型。A型盆地处于短期活动的热地幔柱之上,伴随早期裂谷作用及其随后的热衰减成盆;B型盆地常处于热点和地貌高地之间的部位,盆地沉降长期受地幔持续缓慢下沉控制。

The tectonic setting of the super cratonic basin development and discussion on its forming model

Cratonic basins are the most stable and the most long-lived basins, and also the most important geological record of long-term vertical deformation in the crust and mantle. The prototype area of the largest super cratonic basin in geological history usually exceeds 200×104 km². Therefore, they are regarded as the most significant representatives when studying the origin and evolution of cratonic basins. Research around the world can identify more than 10 super cratonic basins during geologic time. According to the property of basinal basement and the super-continent tectonic evolution of the basin development, the super-cratonic basins can be divided into the A-type and the B-type basins, which would be represented by the West Siberian Basin and the Congo Basin respectively. The A-type basins are formed when the supercontinent exists stably until initial factures begin, overlying on earlier orogenic belt. This kind of basins are of short wavelength, whose shapes are highly irregular and the internal homogeneity are relatively low. The craton basin margin may gradually change with the interaction with back-arc basin or foreland basin. The B-type basins are formed at the end of break-up of supercontinent （at the beginning of the convergence of the next supercontinent）, with the basement being the paleocentonian continent block. This kind of basins are long-wavelength and in the shape of symmetrical wide plate. The A-type basins, located on top of short lived hot mantle plume, experienced the early rifting and subsequent thermal attenuation. And the long-term subsidence of the B-type basins, often sited between the hot spot and topography high, have been under the control of mantle subsidence.