Middle to late Pleistocene climatic and depositional environmental changes recorded in the drilled core of lacustrine sediments in the Kathmandu Valley, central Nepal

Abstract

Since October 2000, we have undertaken core-drilling for pure academic purposes at Kathmandu, Nepal, in order to clarify the continuous paleoclimatic records in the southern slope of the Himalaya and to reconstruct the depositional environmental changes of the ancient lake in Kathmandu (Paleo-Kathmandu Lake) during the last one million years. In this project, we also aimed to clarify the uplift history of the Himalaya and its linkage to paleoclimatic and paleo-environmental changes. We could have penetrated black muddy lacustrine sediments, called the Kalimati Formation, at western central part of the valley (RB core at Rabibhawan) in 2000 (Sakai et al 2001) and southern part of the valley (CP core at Champi and JK core at Jorkhu) in 2003 (Figures 1 and 2). We also could have penetrated the lower part of the fanglomerate, called Itaiti Formation and underlying Lukundol Formation which shows marginal lacustrine facies comprising of fluvial and swamp deposits in 2001 (Sakai 2001a). The longest core drilled at Rabibhawan is 218 m in length and ranges in age from about 700 ka to 10 ka on the base of