Late Miocene vegetation and climate of the Lühe region in Yunnan, southwestern China

Abstract

The Lühe coalmine (25°10′N, 101°22′E) is located in Chuxiong County of Yunnan Province, southwestern China. Its Late Miocene palynoflora consists of 48 sporomorphs that are assigned to 35 natural families, including angiosperms (72.9%), gymnosperms (12.5%) and ferns (14.6%). Three pollen zones are recognized: The assemblages of Zone I are dominated by evergreen oaks, alder and hazel, while pine is present in comparatively low percentages. Zone II is characterized by smaller percentages of oak and hazel and more pine. In Zone III there is an expansion in the number of conifers at the expense of the broad-leaved trees and shrubs. Following the Coexistence Approach, seven palaeoclimatic parameters (Late Miocene) of Lühe are estimated. The mean annual temperature ranged from 13.3 to 20.9°C, the mean temperature of the warmest month from 22.5 to 27.5°C, the mean temperature of the coldest month from 2.5 to 12.6°C, the difference in temperatures of coldest and warmest month from 12.1 to 24.8°C, the mean annual precipitation from 803.6 to 1254.7mm, the mean maximum monthly precipitation from 179.4 to 249.6mm and the mean minimum monthly precipitation from 10.2 to 18.5mm. Comparison with the modern meteorological records indicates that the Lühe area had a warmer subtropical climate with more precipitation during Late Miocene; these data could indicate that extensive uplift of the western Yunnan Plateau had not yet occurred.