环青藏高原大型盆地构造地貌特征与演化比较

A Comparison of the Landscape Characters and Evolution of the Huge Basins Around the Tibetan Plateau

塔里木盆地、柴达木盆地和四川盆地是环青藏高原盆山体系中最为重要的三大盆地,其新生代构造地貌演化引起了研究者的广泛关注。通过对这三大盆地的地貌形态、基底性质、流域属性等特征的对比研究,认为在相似的构造环境下,环青藏高原盆山体系大规模的成山与成盆具有一定的规律:塑性块体显著缩短增厚成山;刚性块体缩短量较小,地壳增厚不明显,因而呈现较为平坦的盆地。刚性地块的形状决定了环青藏高原大型盆地的形状,而相似的构造环境与基底性质使得盆地内部具有相似的构造地貌特征。值得注意的是,这些盆地主体部分垂向上新生代沉积的填充序列主要受控于盆地的流域属性与水动力条件,而受盆地水平应力状态所带来的影响相对较小。同时,盆地内的新生代沉积厚度与流域属性对盆地及其周缘地区的侵蚀基准面、海拔高度、边界断裂的发育都产生了显著的影响,提供了一个深、浅圈层之间相互作用的经典案例。

The Tarim Basin, the Qaidam Basin and the Sichuan Basin are the three most important basins in the Circum-Tibetan Plateau Basin-Range System. The tectonic landform evolution of these basins has been the focus of many researches. Variable physical characters （e.g. landscape, basement, drainage attribute） of these basins have been analyzed in detail. The large-scale formation of basins and ranges under similar tectonic setting exhibits consistent features： rigid crust leads to flat basins, whilst deformable crust leads to mountains. The shape of rigid basement determines the shapes of the basins. Similar tectonic setting and basement features lead to analogous tectonic landform. Notably, the Cenozoic filling of the basins is in close relationship with drainage attribute and hydrodynamic condition rather than horizontal stress field. Meanwhile, the differential thicknesses of the Cenozoic deposits and drainage attributes bring a significant impact on the base level of erosion, modem elevation and the offset of boundary faults.