CHANGES OF NATURAL ENVIRONMENT IN NEPAL HIMALAYA

博卡拉周边湖泊沉积物记录了近1000年来的气候变化：利用日本地质调查局提供的“方便光罩”，从费华湖、贝格纳斯湖和鲁帕湖采集了7个60 ~ 80 cm深的沉积物岩心，并使用SH-20型回声测深仪对这3个湖泊进行了回声测量。对取心沉积物进行x线摄影，进行描述，测定含水率C/N比值等。澄清了尼泊尔-喜马拉雅地区可能与年降水和几个不同事件沉积物（即历史时期的洪水沉积物）相关的弱层压。Siwalik沉积、地层学和古生物学：在尼泊尔中西部Butwal和Narayangarh之间的地区进行了测绘调查。对Siwalik群中新世-上新世淡水软体动物化石区系的系统研究发现了许多新种，新发现了8种Lamellidens arungensis、indonesia narayani、Parreysia binaiensis等。小喜马拉雅变质岩和Ar/Ar年龄测定：对分布在加德满都和博卡拉北部的小喜马拉雅岩石进行了制图，并系统地获得了适合年龄测定的样品。研究了上述3个湖泊的水生植物和加德满都谷地亚热带常绿森林的树种特征。

Climatic changes during the last 1000 years recorded in the sediment of the lakes around Pokhara : Seven sediment cores up to 60 to 80 cm deep, using "convenient light corer mad by Geologic Survey of Japan, were taken from Lakes Phewa, Begnas, and Rupa and echo-sounding survey using SH-20 machine was done in these three lakes. Cored sediments were X-ray radiographed by computerized tomography, made description and measured water content C/N ratio, etc. Weak laminations which might be correlated to annual precipitation and several distinct event sediments, namely flood sediments during the historical age in Nepal Himalaya have been clarified.Siwalik sedimentation, stratigraphy and paleontology : Geomapping surveys were performed at the area between Butwal and Narayangarh, West Central Nepal. Systematic study of the Mio-Pliocene freshwater molluscan fossil fauna of the Siwalik Group has revealed many new species and eight species Lamellidens arungensis, Indonaia narayani, Parreysia binaiensis etc. have been newly described.Lesser Himalayan Metamorphics an Ar/Ar age determination : Lesser Himalayan rocks ditributed in the north of Kathmandu and Pokhara have been mapped and suitable samples for age determination were obtained systematically.The aquatic plant in the above three lakes and tree species characters of ever-green subtropical forest in Kathmandu valley were also studied.