滇西高原第四纪以来的隆升和剥蚀

由滇西高原内古夷平面的抬高、外流水系的河流阶地、高原外营歌海盆地和琼东南盆地的沉积响应，共同揭示滇西高原第四纪以来的快速隆升和剥蚀历史。第四纪以来滇西高原区域性抬升了610～700余米、被剥蚀了1095～1600m，其平均剥蚀速率为0．68～0．94mm／a。根据河流阶地计算出第四纪以来各时段的隆升速率；隆升在0．386～0．296Ma达到峰期，隆升速率为2．24～2．SOmm／a；1．6～0.647Ma隆升速率最缓慢为0．68～0．94mm／a。滇西高原第四纪以来的隆升量和隆升峰期与同期的青藏高原具有相似性，但隆升速率明显低于东喜马拉雅构造结的隆升速率。

UPLIFT AND DENUDATION OF THE WE STERN YUNNAN PLATEAU IN QUATERNARY

Based on the uplift of ancient planation surface,river terrace and sedimentary response of the Yinggehai basin and Qiongdongnan basin (Ying-Qiong basins),the paper suggests that the Western Yunnan Plateau (WYP)experienced a rapid uplift and denudation. The WYP has uplifted regionally about 610~700 m since Quaternary. Silicate detritus budget in Ying-Qiong basins from the WYP,mass balance between denudation areas of the WYP and accumulation areas of the Ying~Qiong basins and paleotemperature of Pliocene basins in the internal plateau were employed respectively to reconstruct denudation thickness of the WYP in Quaternary. About 1 059 m and 1 500~ 1 600 m have been worn away in western and eastern Lancang River,respectively. We take 1 059 m and 1 500 m respectively as denudation thickness of the western and eastern Lancang River,and 1. 6 Ma as the lower limit of Quaternary according to IUGS 1989 scale to calculate average denudation rate of the WYP to be 0.68 mm/a in western and 0. 94 mm/a in eastern Lancang River. Relative uplift rates in different times of Quaternary were calculated according to river terrace,and the results show that the WYP experienced a rapid and slow uplift alternatively. It includes: (1) acceleration uplift from 1. 6 Ma to 0. 296 Ma, (2) slow-footed upIift from 0.296Ma to 0.025 Ma, (3) acceleration uplift again from 0.025 Ma t0 now. Uplift reached its peak in 0. 386~0.296 Ma and peak rate was 2. 24~2. 5 mm/a;secondary rapid uplift was in 0.177~0. 296. Ma and rate 2. 02~2.28 mm/a,and the slowest uplift in 1. 6~0. 647 Ma and rate of uplift 0.68~0.94 mm/a. Some aspects of upllft history of the WYP are very similar to that of Tibetan Plateau because it was affected by uplift of Tibetan Plateau in Quaternary,but meanwhile,it also showed independent evolution characteristics.