FORMATION OF THE HIMALAYAS AND GLOBAL ENVIRONMENTAL CHANGE-COOPERATIVE RESEARCH FOR ESTABLISHMENT OF THE RESEARCH INSTITUTE OF THE HIMALAYAS-

本课题的研究重点和成果总结如下：1.研究方向：参考喜马拉雅隆升引起的环境变化的淡水软体动物的时空分布，阐明了喜马拉雅地区新近纪晚期和第四纪淡水软体动物的区系变化。5Ma以来，喜马拉雅山脉南部地区出现了大量古北元素的显著区系变化，很可能是喜马拉雅隆升引起的强烈季风系统的形成使水鸟的迁徙变得活跃。与喜马拉雅隆升有关的西瓦里克群地质事件建立了西瓦里克群沉积时期古流速的估算方法。在此基础上，确定了各层位的古流速。对白华湖的水质和养分输入进行了调查。由于地质条件的原因，大部分河水在到达湖泊之前就已沉入地下，控制着湖泊的水质。Siwalik山地质灾害对Chor Khola山滑坡进行了详细调查。一个有趣的带有滑动的倒塌结构表明，沿主要构造线的陡峭倾斜地层、砂岩和泥岩之间的对比刚性以及河流的快速切割是导致倒塌的主要原因。

Focuses and results of this research project are summarized as follows ;1. Time and space distribution of freshwater mollusca with reference to the environmental change caused by the Himalayan upliftThe faunal change of freshwater mollusca during the late Neogene and Quaternary in the Himalayan area was illuminated. As for the remarkable faunal change at 5Ma characterized by the introduction of many species of palaearctic elements to the southern area of the Himalayas, it is the most probable that the migration of water birds became active by the formation of intense monsoon system caused by the Himalayan uplift.2. Geological events in the Siwalik Group concerned with the Himalayan upliftThe method for estimation of the palaeoflow velocity during the sedimentation of the Siwalik Group was established. Based on the method, the palaeoflow velocity of each horizon was shown definitely.3. Water environment in Pokhara BasinThe water quality and the nutrient input in Phewa Lake was investigated. Because of the geological condition, the most of river water sink into the underground before reaching the lake, and it controls the water quality of the lake.4. Geological disaster in the Siwalik hillsThe detail investigation about the landslide along the Chor Khola was carried out. An interesting toppled structure with sliding indicates that steeply dipping strata along the major tectonic line, contrasting rigidity between sandstone and mudstone, and rapid dissection by a river were the major causes of the toppling.