天津北部4.00Ma BP以来古植被与古气候

Palaeovegetation and palaeoclimate since 4.00 Ma BP in northern Tianjin

依据CQJ1孔275块孢粉样品分析结果,结合岩性特征和测年资料,建立了天津北部4.00MaBP以来古植被与古气候变化序列。大约在3.60—4.00MaBP,天津北部植被以荒漠草原为主,气候冷干;3.44—3.60Ma,BP植被为疏林草原,气候温和湿润;3.18—3.44MaBP植被为荒漠草原,气候冷干;2.58—3.18MaBP植被以针阔叶混交林草原为主,气候温暖湿润;1.90—2.58MaBP植被以疏林草原为主,气候温凉偏干;1.74—1.90Ma,BP植被为荒漠草原,气候冷干;1.30—1.74MaBP植被以针阔叶混交林为主,气候温暖潮湿;0.78—1.30MaBP植被为以针叶树种为主的针阔叶混交林草原,气候温和湿润;0.15—0.78MaBP植被以针阔叶混交林为主,气候温暖潮湿;0.15MaBP以来,孢粉丰度呈现有规律的变化,3个高丰度层段分别相当于MIS(海洋氧同位素)1、3、5阶段,与河北平原东部具有可比性。

Based on the analysis of the spore-pollens in 275 samples from borehole CQJ1 drilled in northern Tianjin,combining with lithology and dating informations,the sequences of palaeovegetation and palaeoclimate evolvement since 4.00 Ma BP have been established. During the period of 3.60-4.00 Ma BP,the vegetation mainly was desert steppe,and the climate was cool and dry in northern Tianjin.During the period of 3.44-3.60 Ma BP,the vegetation was grass savanna,and the climate was warm and wet. During the period of 3.18-3.44 Ma BP,the vegetation was desert steppe,and the climate was cool and dry.During the period of 2.58-3.18 Ma BP,the vegetation was grassland with mixed forest of coniferous trees and broad leaved trees,and the climate was warm and wet.During the period of 1.90-2.58 Ma BP,the vegetation mainly was grass savanna,and the climate was warm and dry.During the period of 1.74-1.90 Ma BP,the vegetation was desert steppe,and the climate was cool and dry.During the period of 1.30-1.74 Ma BP,the vegetation mainly was mixed forest of coniferous trees and broad leaved trees,and the climate was warm and wet.During the period of 0.78-1.30 Ma BP,the vegetation was grassland with mixed forest of coniferous trees and some broad leaved trees,and the climate was warm and wet.During the period of 0.15-0.78 Ma BP,the vegetation mainly was mixed forest of coniferous trees and broad leaved trees,and the climate was warm and wet.Since 0.15 Ma BP,the abundance of pollen changed regularly,and the 3 intervals with high abundance of pollen corresponded with the stages MIS1,MIS3 and MIS5 respectively,which are accord with that of intervals in eastern Hebei Plain.