青藏高原隆升对云南高原环境的影响

讨论了云南高原环境从上新世至早更新世对青藏高原隆升的响应。在上新世 ,云南高原普遍发育一套粘土岩、亚粘土岩、粉砂岩及褐煤的湖相、湖沼相沉积 ,大致以红河断裂为界 ,西厚东薄 ,说明在上新世云南高原内部总体构造环境较稳定 ,但西部盆地下沉的速度大于东部盆地。在早更新世 ,云南高原的沉积相和厚度都发生了较大的变化。红河断裂以西为洪冲积相的砾石层 ,厚度薄 ;滇西北主要为河流相的砾石层和砂层 ,略较滇西的厚 ;滇中地区为河湖相和河流相的砂质粘土层、粘土层、砂层和砾石层 ,厚度较大。说明进入早更新世 ,云南高原隆升强度明显加强 ,而且从西部向东部逐渐推进。在早更新世晚期 ,在青藏高原的昆黄运动的影响下 ,全区发生了一次显著的构造运动———元谋运动 ,造成下更新统的褶皱、断裂变形和金沙江的全线贯通。

EFFECT OF THE TIBETAN PLATEAU UPLIFTING ON GEOLOGICAL ENVIRONMENT OF THE YUNNAN PLATEAU

This paper gives a discussion about the Yunnan Plateau responding to the uplifting of the Tibetan Plateau in the geological environment during Pliocene and Early Pleistocene. In Yunnan Province there are wide-ranging Pliocene lacustrine and limnetic claystone, sandy claystone, siltstone and lignite. From the Pliocene stratigraphical thickness, they are generally relatively thick in the western region to the northwest-southeast Honghe Fault crossing the central Yunnan, while comparatively thin in the eastern region to the fault. It shows that the Yunnan Plateau was under the setting of the relative weak tectonic movement during Pliocene, but the sinking speeds of basins in the western region were faster than that of basins in the eastern region.From Pleistocene on, the sedimentary facies and stratigraphical thickness occurred an important change. In west Yunnan it consists of the thin pluvial-fluvial gravel beds and in northwest Yunnan the fluvial pebble sediments, whereas in the central Yunnan the thick fluvial-lacustrine and river sandy clay, clay, sand and pebble sediments formed. It clearly shows that the uplifting of the Tibetan Plateau strongly affected the tectonic movement in the Yunnan Plateau during Early Pleistocene, and the affecting strength gradually weakened from west to east. Under the effect of the Kunhuang movement that happened in the Tibetan Plateau at late Early Pleistocene, an obvious tectonic movement happened in the Yunnan Plateau, named Yuanmou movement. The tectonic movement resulted in the folds and faults in Pliocene and Early Pleistocene strata, and formation of the Jinsha River.