中蒙边界地区晚中生代伸展盆地的结构、演化和成因

Structure,evolution and origin of Late Mesozoic extensional basins in the China-Mongolia border region

中蒙边界地区在晚侏罗世晚期—早白垩世发育一个广阔的伸展盆地体系,内部由许多不同规模的次级盆地所组成。盆地体系大致经历了两个发展阶段,早期阶段普遍发育相互独立的次级盆地,而晚期阶段则发生以次级盆地侧向相互连接为特征。相互连通的次级盆地进一步演化为大型次级盆地,形成盆地体系内的沉积和沉降中心,并在平面上呈条带状。与此同时,由于应力逐渐集中在大型次级盆地边界断层之上,处于应力影中的次级盆地停止发育。中蒙边界地区晚中生代的伸展盆地体系的形成与地壳浅部的伸展作用相关,动力学成因机制很可能与增厚岩石圈的重力垮塌有关。

A broad extensional basin system developed in the China-Mongolia border region in Late Juras-sic-Early Cretaceous times,and was internally built up by a number of subbasins of various scales.The basin system experienced two stages of structural development.The first stage was characterized by wide occurrence of isolated small subbasins ,while the second stage was a period when the subbasins began to coalesce laterally.The linked subbasins gradually evolved into relatively large subbasins ,serving as main de-positional and subsidence centers of the basin system and exhibiting a ribbon-like shape in map view.In contrast,the subbasins in the stress shadow became inactive and dead as a result strain localization on the linked through-going basin-bounding faults.It is considered that the formation of the Late Mesozoic basin system bore upon extension in the shallow level of the crust,which arose dynamically from gravitational collapse of the crust beneath the China-Mongolia border region that had been overthickened by the pre-ceding compression.Some problems are accordingly raised that need further investigations in the future rele-vant studies.