非洲南部赞比西河流域距今30~5 ka的孢粉组合及古气候变化  

Pollen assemblages and paleoclimate changes from 30 ka B.P.to 5 ka B.P.in Zambezi River basin,southern Africa

作　　者：万正 张虎才 聂军胜[1] 赵永涛 苗运法 张晓楠 赵雪琴 王梓莎 WAN Zheng;ZHANG Hucai;NIE Junsheng;ZHAO Yongtao;MIAO Yunfa;ZHANG Xiaonan;ZHAO Xueqin;WANG Zisha(Key Laboratory of Western China's Environmental Systems,Ministry of Education,College of Earth and Environmental Sciences,Lanzhou University,Lanzhou 730000,Gansu;Key Laboratory of Desert and Desertification,Northwest Institute of Eco-Environment Resources,Chinese Academy of Sciences,Lanzhou 730000,Gansu;Institute for Ecological Research and Pollution Control of Plateau Lakes,Yunnan University,Kunming 650500,Yunnan;University of Chinese Academy of Sciences,Beijing 100049;College of Marine Sciences,Shanghai Ocean University,Shanghai 201306)

机构地区：[1]兰州大学资源环境学院,西部环境教育部重点实验室,甘肃兰州730000 [2]中国科学院西北生态环境资源研究院,中国科学院沙漠与沙漠化重点实验室,甘肃兰州730000 [3]云南大学高原湖泊生态与治理研究院,云南昆明650500 [4]中国科学院大学,北京100049 [5]上海海洋大学海洋科学学院,上海201306

出　　处：《第四纪研究》2023年第3期899-910,共12页Quaternary Sciences

基　　金：国家自然科学基金重点国际(地区)合作研究项目(批准号:41820104008和42161144012);中国科学院青年创新促进会项目(批准号:2022439)共同资助。

摘　　要：非洲东南部晚更新世植被重建及对比研究有助于理解区域气候变化过程和驱动机制。本研究依托国际大洋发现计划IODP361航次科学任务所获取的U1477B海洋钻孔,对其上部4~37 m的沉积岩芯的79个样品进行了孢粉分析,重建了30~5 ka B.P.的区域植被和气候变化历史。研究结果显示,钻孔岩芯整体以草本植物禾本科(Poaceae)和莎草科(Cyperaceae)花粉为主,平均约占75.5%;木本植物花粉较少,以罗汉松科(Podocarpaceae)、豆科(Fabaceae)、使君子科(Combretaceae)和红树科(Rhizophoraceae)等为主;孢粉组合记录了钻孔孢粉源区赞比西河流域的植被特征。在时间演化序列上,钻孔沉积物孢粉组合变化反映出明显的冰期-间冰期(全新世)的植被变化特征:末次冰期(30~17 ka B.P.)以禾本科、莎草科等草本花粉为主,平均约占82.2%,以草原/草甸植被占优势,推测在流域低海拔平原开阔草原广泛发育;罗汉松科为代表的山地森林在冰期也相对发育,指示了相对凉爽潮湿的气候环境;冰消期(17.0~10.5 ka B.P.)禾本科花粉保持稳定平均约占38.3%,而莎草科花粉含量在前期略有增加后呈持续下降的趋势,反映了低海拔流域逐渐干旱的气候条件,非洲山地森林植被罗汉松科花粉达到最高值,反映了高海拔山地森林植被出现扩张;全新世早-中期(10.5~5.0 ka B.P.)罗汉松科花粉占比减少,而干旱林地典型植被豆科、使君子科等花粉增加,指示全新世早-中期气候相对温暖干燥;而红树科花粉占比迅速增加,指示海平面迅速上升扩大了适宜红树林生长的沿海空间。末次冰期到全新世中期流域内植被组成变化指示末次冰期相对潮湿寒冷、冰消期降水减少、全新世早-中期温暖干燥的气候条件,降水变化与同纬度(18°S)日照强度变化有较好的一致性。因此,钻孔孢粉记录的植被演化及降水过程可能受控于当地夏季日照强度并且对北半球高纬度冷�The study of Late Pleistocene vegetation reconstruction in southeastern Africa is helpful to understand the process and driving mechanism of regional climate change.In this study,79 samples with a depth of 4~37 m from southern Africa at the International Ocean Discovery Program(IODP)voyage 361 scientific mission U1477B core(19°29.2822′S,36°54.8958′E)were analyzed by palynological method to reconstruct the vegetation and climate history during 30~5 ka B.P.The results showed that pollen records were dominated by herbaceous pollen(mainly Poaceae and Cyperaceae,accounting for 75.5%on average)with less woody pollen(mainly Podocarpaceae,Fabaceae,Combretaceae,and Rhizophoraceae).The pollen assemblage reflects the vegetation characteristics of the Zambezi River basin,the source of the borehole pollen.In terms of time evolution sequence,the changes of pollen assemblages in borehole deposits reflect the obvious characteristics of vegetation changes glacial-interglacial period(Holocene):During the last glacial period(30~17 ka B.P.),Poaceae and Cyperaceae pollen dominated,accounting for 82.2%on average.So grassland/meadow vegetation is dominated,reflecting the extensive development of open grasslands in low-altitude plains of the basin.The mountain forest represented by Podocarpaceae also developed during this period,indicating a relatively cool and humid climate.During the last deglacial(17.0~10.5 ka B.P.),Poaceae remained stable and accounted for about 38.3%,and Cyperaceae increased slightly in the early stage and then continued to decrease,reflecting the gradually drought climate conditions in the low-altitude basin.Meanwhile,the highest value of the Podocarpaceae implied the expansion of the high-altitude mountain forest vegetation.During the Early-Middle Holocene(10.5~5.0 ka B.P.),the proportion of Podocarpaceae decreased while the typical vegetation of dry woodlands,such as Fabaceae and Combretaceae,etc.increased,indicating a relatively warm and dry climate during the Early-Middle Holocene.Moreover,the rapid incr

关 键 词：非洲 赞比西河 孢粉 植被 末次冰盛期 全新世 

分 类 号：P534.63[天文地球—第四纪地质学] Q913.84[天文地球—古生物学与地层学] P532[天文地球—地质学]