Plant macrofossils from the sedimentary sequence of Churia Group, Nepal : their phytogeographic and palaeoclimatic significance

摘要

In the present investigation, taxonomic studies were carried out on recently discovered plant macrofossils from the Churia Group (Miocene) of sediments exposed in the Arjun Khola area, Nepal. The present study has revealed occurrence of sixteen fossil species belonging to twelve tropical dicotyledonous families. Of these, eleven species are recorded for the first time from the Miocene of Nepal. As the nearest living relatives of the macroflora reported here, are restricted to the northeast part of India and southeastern Asia, it is plausible that tropical forests and moist conditions were prevalent during the Miocene times in this region. The above inferences have been corroborated using the Coexistence Approach (CoA) analysis for palaeoclimate estimation. It also indicates prevalence of tropical climatic conditions during the Miocene in the Arjun Khola area, with Mean Annual Temperature (MAT) of about 20°-28.5°C, Warm Month Temperature (WMT) of about 29°-34℃, Cold Month Temperature (CMT) of about 15°- 22℃ and Mean Annual Precipitation (MAP) of about 1800 mm-3200 mm.