红水河上游北盘江峡谷发育与演化研究

The Beipan River between Buna and Dongqing is a bridge connecting the upper and lower reaches of the Beipan River, therefore plays a critical role in the research on the formation and evolution history of the whole reach. The detailed explanation for this challenge issue is still imperfect resulting in an unfavorable setting for the study on the formation and evolution of the Beipan River. Fluvial terraces and riverside caves are landforms that were at one time constructed and maintained as the active floor of a river but are now abandoned. According to fluvial geomorphology, these geomorphic surfaces can record the formation and evolution history of the related river, being considered as a direct archive of long-timescale fluvial history. Recent studies reveal that a series of well-preserved fluvial terraces and riverside caves were formed along the reach of the Beipan River between Buna and Dongqing. In this propose, a combined approach of field investigation, difference GPS measurement, remote sensing, and DEM analysis is adopted to establish a complete sequence for these planation surfaces and fluvial terraces by outlining their distribution and characters. The formation ages of these geomorphic surfaces will be determined by the cosmogenic nuclides, ESR, TL/OSL, and C-14. Furthermore, the composition characteristics of the fluvial deposits on these geomorphic surfaces will also be analyzed by petromineralogy, elemental tracer technique, and fabric measurement to reconstruct river directions during the formation processes of different geomorphic surfaces. These obtained archives in fluvial sediments and geochronology will be assembled to show the scenario of the Beipan River formation.

北盘江补那-董箐段是北盘江中下游的关键河段，在河流下切、峡谷发育研究中处于关键位置。对北盘江发育、演化认识还比较缺乏，这对研究贵州高原抬升、岩溶峡谷地貌演化十分不利。河流阶地是废弃的古河漫滩，层状洞穴反映的是古潜水面的位置，它们记录了地质时期河流形成演化的历史，是研究河流形成演化的重要载体。已有研究表明，北盘江补那-董箐段分布河流阶地和层状洞穴。本项目拟通过野外考察、差分GPS测量、遥感和DEM分析研究该段北盘江沿岸阶地、层状洞穴的分布和特征，建立层状洞穴地貌面序列；通过宇成核素、ESR、TL/OSL和14C等测年方法确定它们的形成年代；通过岩石/重矿物、示踪元素、沉积物组构等方法研究地貌面沉积物特征，恢复各地貌面发育时期河流水文特征，进而重建北盘江河流峡谷发育、下切和演化过程，并探讨影响岩溶峡谷发育的控制因子。

云贵高原位于青藏高原东南侧，新生代以来伴随着青藏高原的隆升而发生了一系列构造抬升运动。北盘江发源于滇东，自西北向东南流经云贵高原向广西丘陵过渡的斜坡地带。通过对北盘江流域提取河流地貌参数来研究新构造运动，定量化地分析研究区的构造地貌特征。表明：4种地貌参数能很好地反映区域构造运动和地貌特征；垭都—紫云断裂在内的一系列断层系统对北盘江中游地区的河流地貌，水系格局、河谷形态等起到了控制性的作用；北盘江流域的地貌演化过程受地质构造作用影响较大，而且区域差异明显。北盘江花江峡谷段响应高原抬升发生强烈下切，20万年以来花江峡谷下切速率达到1.1m/ka，河流以“地下河-崩坍”式的演化模式形成深切峡谷。.