CHANGES OF NATURAL ENVIRONMENT IN NEPAL HIMALAYA

点击翻译按钮获取中文摘要

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.