杭州湾晚第四纪沉积与古环境演变

Late Quaternary sediments and paleoenvironmental evolution in Hangzhou Bay

通过对杭州湾第四系钻孔的年代地层学、沉积学、古环境学等多学科综合分析,认为XZK169孔全新世沉积始于孔深17.35m处(年代约为10～9kaBP),其下至孔深86.40m沉积属晚更新世。整个沉积层中可分出3个海进—海退旋回晚更新世早期以陆相沉积为主,出现河湖相—滨海湖泊相—河湖相沉积,气候为温凉干燥—温暖湿润—温凉干燥;晚更新世中晚期出现河湖相—潮滩湖相—浅海相—河口湾相沉积,气候为温凉干燥—寒冷干燥—温凉—暖热湿润—温热湿润;经历了末次冰期侵蚀后,全新世出现浅海相—河口湾相沉积,气候以暖热湿润—温暖湿润为主。约在5kaBP,杭州湾与长江口分离。

Through the comprehensive analyses on chronostratigraphy, sedimentology, and paleoenvironmentology of the Quaternary bore （XZK169）in Hangzhou Bay, it is proposed that the Holocene sedimentation began from the depth of 17.35 m （about 10-9 ka B P）,and the strata below this level to the depth of 86.4 m belong to the Late Pleistocene. In the profile, three cycles of trans- gression-regression can be recognized. In the early period of Late Pleistocene, mainly continental sediments were developed, river-lacustrine facies, lagoon-lacustrine facies, river-lacustrine facies respectively appeared, and the paleoclimate changed from temperament cool-arid, warm and moist, to temperament cool-arid. In the mid-late period of Late Pleistocene, river-lacustrine facies, tidal-flat and lagoon facies, shallow marine facies, estuary facies appeared and the paleoclimate changed from temperament cool-arid, cold and arid, temperament cool, warm hot and moist, to warm and moist. After the erosion during the last glaciation, shallow marine-estuary facies appeared in the Holocene, and the paleoclimate changed from warm hot and moist, to warm and moist.The Hangzhou Bay separated from the Changjiang River mouth in around 5 ka B P.