367 resultados para Palaeoclimate


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A survey of the Neogene flora and vegetation pattern of the Pannonian domain based on 18 selected fossil plant assemblages is given. Flora and vegetation patterns are based on well-documented and studied fossil plant assemblages (macrofloras, primarily leaves). A general but slow cooling trend is definitely observable after the Early Miocene as reflected by both quantitative climate reconstructions and floristic change, i.e. decrease of diversity, slow disappearance of thermophilous and exotic elements, as well as decrease in the variety of vegetation types. A significant decline of coldest month temperatures (as compared to warmest month temperatures) must have played a defining role in forming flora and vegetation through the Neogene.

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The Miocene Lincang leaf assemblage is used in this paper as proxy data to reconstruct the palaeoclimate of southwestern Yunnan (SW China) and the evolution of monsoon intensity. Three quantitative methods were chosen for this reconstruction, i.e. Leaf Margin Analysis (LMA), Climate Leaf Analysis Multivariate Program (CLAMP), and the Coexistence Approach (CA). These methods, however, yield inconsistent results, particularly for the precipitation, as also shown in European and other East Asian Cenozoic floras. The wide range of the reconstructed climatic parameters includes the Mean Annual Temperature (MAT) of 18.5-24.7 °C and the Mean Annual Precipitation (MAP) of 1213-3711 mm. Compared with the modern Lincang climate (MAT, 17.3 °C; MAP, 1178.7 mm), the Miocene climate is slightly warmer, wetter and has a higher temperature seasonality. A detailed comparison on the palaeoclimatic variables with the coeval Late Miocene Xiaolongtan flora from the eastern part of Yunnan allows us to investigate the development and interactions of both South Asian and East Asian monsoons during the Late Miocene in southwest China, now under strong influence of these monsoon systems. Our results suggest that the monsoon climate has already been established in southwest Yunnan during the Late Miocene. Furthermore, our results support that both Southeast Asian and East Asian monsoons co-occurred in Yunnan during the Late Miocene.