The Spore-Pollen Assemblage Characteristics And The Climate Evolution In Jiaozuo Since The Middle Pleistocene

As for the frequently natural disasters, earthquake prediction is becoming more and more important. This thesis relies on the project “Jiaozuo’s hidden active fault detection and seismic hazard assessment” whose research is to ascertain the existence of the seismic activated faults and carry out the representative borehole detecting in the target area of Jiaozuo. This thesis is to identify the climate of Jiaozuo in Henan province and have some comparison with global climate change since the mid Pleistocene. As the starting point, the detection of the standard drilling depends on the properties of the spore-pollen assemblage and the laws of the ancient plant evolution. At the same, this thesis has consulted the drilling data, the petrography character and the granularity characteristics to analyze the data and draw the following conclusions.⑴ The spore-pollen assemblage of Jiaozuo can be divided into five pollen components and four subzone pollen components. Pollen assemblage zone(I) indicates the vegetation types of mixed wood- grassland and reflects the climate characteristic of warm and moderately dry condition. Pollen assemblage zone(II a) indicates the vegetation types of mixed wood- grassland and reflects that the climate characteristic is cooler and relative dry. Pollen assemblage zone(II b) indicates the vegetation types of mixed wood- grassland and reflects a warm and moist climate. Pollen assemblage zone(III a) indicates the vegetation types of mixed wood- grassland and reflects the climate characteristic of cool and moderately humid. Pollen assemblage zone(III b) indicates the vegetation types of mixed wood- grassland and reflects a warm and moist climate. Pollen assemblage zone(IV) indicates the vegetation types of coniferous forest- grassland and reflects a cold and dry environment. Pollen assemblage zone(V) indicates the vegetation types of mixed wood and reflects a warm and moist climate.The alternated emergence of the mixed broadleaf-conifer forest- grassland and coniferous forest-grassland in Jiaozuo at Pleistocene correspond to the warm of the interglacial period and the cold of the glacial period between the MIS7 and the MIS1.However, It is very dry at the middle of Pleistocene in Jiaozuo which cannot corresponds to the global humidity. In the Holarctic, the vegetation is bloom in which the mixed broadleaf-conifer forest dominate. It represents the warm climate after the ice period, which associated with global climate characteristics.