瓯江三角洲南翼晚第四纪孢粉、藻类记录及其古气候意义  

PALYNOLOGICAL CHARACTERS OF LATE QUATERNARY IN THE SOUTH FLANK OF THE OUJIANG RIVER DELTA AND THEIR PALEOCLIMATE IMPLICATIONS

作　　者：张梦莹[1] 范代读[1] 吴国瑄[1] 尚帅[1] 陈玲玲[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《第四纪研究》2012年第6期1234-1247,共14页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41076016和40830107);中国地质调查局海保工程专项项目(批准号:GZH201100203);中央高校基本科研业务费专项资金联合资助

摘　　要：YQ0902孔位于瓯江三角洲南翼的海岸平原上,沉积相与AMS^(14)C测年分析表明,钻孔底部为MIS 3阶段的河湖相沉积,之上为形成于MIS 2的硬粘土层。约在10cal.kaB.P.海侵到达本区,沉积了一套厚约29m的海侵-海退沉积旋回。古气候重建表明,50～35cal.kaB.P.凉爽干燥,35～25cal.kaB.P.温和湿润,25～10cal.kaB.P.寒冷干燥,10～9cal.kaB.P.凉爽偏干,9.0～6.5cal.kaB.P.暖热潮湿,6.5～4.8cal.kaB.P.温凉偏干,4.8～1.8cal.kaB.P.温暖潮湿,1.8cal.kaB.P.之后趋同于现代气候。受中全新世东亚夏季风减弱影响,研究区降雨减弱始于6.5cal.kaB.P.,这与前人研究认为季风区降雨减弱年限随纬度增加有时滞的观点相一致。孢粉记录的两次百年尺度(6.9～7.3cal.kaB.P.和5.0～5.5cal.kaB.P.)降温事件,与全球性强降温事件(7.3cal.kaB.P.和5.5cal.kaB.P.)有较好的对应关系。Borehole YQ0902（27°55＇N, 120°51＇E） was drilled from the southern coastal plain of Oujiang River delta,with a total length of 41.9m.Sediment cores were split and described in detail,including color,sedimentary texture and structure,and stratigraphical boundaries before sampling.Fourteen AMS14C dating samples were collected and sent to Beta Analytic Company for dating.Forty-five samples were collected with roughly 1-m sampling interval for palynological studies. Facies analysis together with AMS 14C age data showed that the lower section of the core was deposited during MIS 3 in a fluvial-lacustrine environment,topped by the paleosol formed during the MIS 2 low sea-level stage.A complete transgressive-regressive succession of 29m thick overlying the paleosol,was presumed to deposit after 10cal.kaB.P. when the transgression reached the area.Pollen-spore analysis suggested that the Late Quaternary paleoenvironmental evolution can be divided into eight stages.1）Between 50cal.kaB.P. and 35cal.kaB.P., the climate was cool and dry,and the sea-level was at least 40m lower than the present.2）During the period of 35～25cal.kaB.P.,it was a warm and humid interval.3）From the beginning of MIS 2 to 10.0cal.kaB.P.,the climate changed into cold and dry,and the study area was exposed to undergo long-term pedogenesis before terminated by the last deglacial transgression.4）In the interval of 10.0～9.0cal.kaB.P.,the climate was still cool and dry but the area was flooded by the transgression to deposit an intertidal-flat succession.5）The period of 9.0cal.kaB.P. to 6.5cal.kaB.P. was warm and wet,corresponding to the mid-Holocene Climatic Optimum,and the sea-level gradually reached its highest position（close to or a little higher than the present）,resulting in maximum transgression to deposit neritic facies in the study area.6）During 6.5cal.kaB.P. to 4.8cal.kaB.P.,the climate became cool and dry after termination of the mid-Holocene Climatic Optimum,and a shoaling-upward succession was initiated after the d

关 键 词：瓯江三角洲 古气候 海平面 沉积环境 东亚夏季风 全新世 

分 类 号：P343.5[天文地球—水文科学] Q913.84[天文地球—地球物理学]