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    钱塘江北岸晚第四纪沉积与古环境演变

    Late Quaternary sediments and paleoenvironmental evolution on the northern bank of the Qiantang River

    • 摘要: 提要:通过钱塘江北岸第四系钻孔岩心的岩石学、年代学以及孢粉带、有孔虫化石组合的综合分析,认为HQB7孔全新世沉积始于孔深35.7 m处(年代约为10.4 ka B.P.),其下至孔深71.1 m属晚更新世沉积,并将该孔31.2 ka B.P.以来的古环境演变划分为5个发展阶段。系统阐述了各阶段的古植被、古气候与古地理特征,指出第2阶段(20.1~10.4 ka B.P.)处于低海面时期,气候凉冷干燥,其早期可能对应于末次盛冰期(LGM);第4阶段(7.5~2.5 ka B.P.)为高海面时期,气候温热潮湿,相当于与全球变化相一致的全新世气候适宜期。本区晚第四纪3万年以来的气候变化特点与中国南方的深圳湾地区有很好的可比性。

       

      Abstract: Abstract:Based on a comprehensive analysis of lithostratigraphy, chronostratigraphy, spore-pollen zones and foraminiferal assemblages of the Quaternary bore core from the northern bank of the Qiantang River, the author holds that the Holocene sedimentation began from the depth of 35.7 m (about 10.4 ka B.P.), and the strata from this level to the depth of 71.1 m should belong to Late Pleistocene. The author also divides the paleoenvironmental evolution of this hole since 31.2 ka B.P. into five development stages, with a systematic description made in such aspects as paleovegetation, paleoclimate and paleogeography of each stage. It is pointed out that the second stage (20.1~10.4 ka B.P.) was within the low sea level period, during which the climate was cool, cold and dry, that the early period of the second stage may correspond to the glacial maximum of last glaciation, and that the fourth stage (7.5~2.5 ka B.P.) was within the high sea level period, when the climate was warm, hot and damp, corresponding to the Holocene climate optimum that was in line with the global change. The climate change of the last 30,000 years since Late Quaternary in this area exhibits a good comparability with that of the Shenzhen Bay area in southern China.

       

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