Palynology, Paleovegetation And Paleoclimate Of Neogene Central-Western Yunnan, China

The Neogene is a key stage of terrestrial environmental evolution in Yunnan. Three stratigraphic sections including Luhe (Late Miocene), Yangyi and Longling (Late Pliocene) were selected to reconstruct vertical landscape of paleovegetation in these areas, based on palynological data. According to principle of the coexistence approach, seven quantitative paleoclimatic parameters of each deposit area were obtained by using meteorological data (1951-1980) of the distribution area of extant taxa found each palynoflora in China.Luhe palynoflora comprises of 52 palynomorphs belonging to 38 families. The percentage of angiosperms is 73.1%, gymnosperms 11.5%, pteridophytes 15.4%.Liihe palynological data indicate a vertical paleovegetational landscape: evergreen broad-leaved forest dominated by Castanopsis, Lithocarpus, Cycobalanopsis and Anacardiaceae etc occurred on the slopes near the deposit site; mixed coniferous/broad-leaved forest and coniferous forest occurred on the area of high elevation, and main elements were Tsuga, Podocarpus, Pinus, Picea and Abies etc.Seven paleoclimatic parameters of Liihe area estimated includeMAT(13.3-20.9C), WMT(22.5-27.5C), CMT(2.5-12.6C), DT(12.1-24.8C), MAP(803.6-1254.7mm), MMaP( 179.4-281.9mm) and MMiP(10.2-l8.5mm).Yangyi palynoflora comprises of 52 palynomorphs belonging to 32 families. The percentage of angiosperms is 61.5%, gymnosperms 9.6%, pteridophytes 25.0%, algae 3.9%.Yangyi palynological data indicate a vertical paleovegetational landscape: humid evergreen broad-leaved forest occurred on the slopes near the deposit site, and main elements were Castanopsis, Lithocarpus, Cycobalanopsis, mixed with Anacardiaceae, Myrtaceae, Palygonaceae, Euphorbiaceae and Liquidambar, and abundant ferns grew in the forest; mixed coniferous/broad-leaved forest and coniferous forest distributed on the area of high elevation, dominated by Tsuga, Podocarpus, Pinus, Picea and Abies.Composition of the flora indicate the paleoelevation of diposit site was 2000m at most.Seven paleoclimatic parameters of Yangyi area estimated include MAT(13.3-20.9C), WMT(22.5-27.5C), CMT(1.9-12.6C), DT(12.3-25.8C), MAP(797.5-1254.7mm), MMaP(172.4-249.6mm) and MMiP(7.2-12.7mm).Longling palynoflora comprises of 86 palynomorphs belonging to 61 families, and consist of angiosperms (69.0%), gymnosperms (4.6%), pteridophytes (24.1%) and algae (2.3%).Longling palynological data indicate a vertical paleovegetational landscape: humid evergreen broad-leaved forest occurred on the slopes near the deposit site, and dominant elements were Castanopsis, Lithocarpus, Cycobalanopsis, mixed with Ericaceae, Anacardiaceae and Sapindaceae etc, and abundant ferns grew in the forest; the mixed coniferous/broad-leaved forest and coniferous forest distributed on the areaof high elevation, dominant elements were Tsuga, Pinus, Picea and Abies.Seven paleoclimatic parameters of Longling area estimated include MAT(18.6-22.1C), WMT(22.5-27.5C), CMT(9.7-15.1C), DT(12.3-18.1C), MAP(815.8-1254.7), MMaP(172.4-249.6mm) and MMiP(9.8-l 1.3mm).Present palynological studies together with previous palynological data suggest a montane subtropical warm and humid climate during the Neogene period in Yunnan. The climatic fluctuations reflected by Neogene palynofloras of Yunnan were less intense than those of Northern China.