Pollen Assemblage And Palaeoenvironment For Quaternary Geology In Yinchuan Plain

Quaternary sediments are rich in stratigraphic information,which has been recorded in many historical periods.The pollen has become an important indicator of the paleovegetation and palaeoclimate reconstruction as it record the information form the environment changes,and preserved well in the stratum.The analysis of pollen and grain size of sediments,combining with 87 surface pollen data,we are able to reconstruct climate in Yinchuan plain using the weighted average method of least squares(WAPLS)modle.Since the Middle Pleistocene,the conversion of climate from warm and wet to cold and dry,the vegetation experience coniferous and broad-leaved mixed forest and brush grassland,coniferous forest and grassland,coniferous and broad-leaved mixed forest and grassland,sparse woods and grassland,grassland,coniferous forest and grassland.Since late Pleistocene,the climate from cold and dry to warm and wet,the vegetation evolution stage is coniferous forest and grassland,coniferous and broad-leaved mixed forest and brush grassland,coniferous forest and grassland.Since Holocene,the climate is warm and dry,the vegetation is the grassland vegetation.Sediments are mainly fluvial deposits,and have different sedimentary characteristics with the changes of hydrodynamic conditions.The YE07 has a very good comparability with the CK1,and they are similar to the climatic characteristics.Sediment has a better response to global climate change,which indicates that climate change in Yinchuan plain is affected by global climate factors and has unique regional characteristics.