南黄海黑碳记录的中国东部晚上新世以来C_(3)/C_(4)植被演化  

EVOLUTION OF C_(3)/C_(4)VEGETATION IN EASTERN CHINA SINCE THE LATE PLIOCENE:EVIDENCE FROM BLACK CARBON RECORD IN THE SOUTH YELLOW SEA

作　　者：陈州美子 万世明[1,2] 张晋 黄杰[1] 刘书明[4] 李安春 CHEN Zhoumeizi;WAN Shiming;ZHANG Jin;HUANG Jie;LIU Shuming;LI Anchun(Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,Shandong;Laboratory for Marine Geology,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,Shandong;University of Chinese Academy of Sciences,Beijing 100049;China Offshore Fugro Geosolutions(Shenzhen)Co.,Ltd.,Shenzhen 518068,Guangdong)

机构地区：[1]中国科学院海洋研究所,中国科学院海洋地质与环境重点实验室,山东青岛266071 [2]青岛海洋科学与技术试点国家实验室海洋地质过程与环境功能实验室,山东青岛266237 [3]中国科学院大学,北京100049 [4]中海辉固地学服务(深圳)有限公司,广东深圳518068

出　　处：《第四纪研究》2021年第4期948-964,共17页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42076052);中国科学院(B类)战略性先导科技专项项目(批准号:XDB40010100)共同资助。

摘　　要：陆地植被是全球生态系统的重要组成部分,其C_(3)/C_(4)组成类型及演化进程对于理解过去生态系统对全球变化的响应及适应机制具有重要科学意义。晚上新世以来东亚C_(4)植被扩张的时间、过程和机制等仍存很大争议,尤其缺少长江流域C_(3)/C_(4)植被相对丰度演化的地质记录及不同纬度植被演化的时空综合对比。本研究利用大陆架科学钻探计划在南黄海钻取的CSDP-1孔约300.10 m长的岩芯沉积物的黑碳含量、通量及碳同位素组成,重建了晚上新世以来中国东部地区C_(3)/C_(4)植被演化历史。研究发现,在晚上新世(约3.0~2.6 Ma),黑碳碳同位素组成发生明显正偏,指示沉积物源区长江流域的C_(4)植被相对丰度的增加,可能受到了中低纬度地区干旱化增强及大气CO_(2)浓度下降的共同影响;而中高纬度如黄土高原地区的C_(4)植被则相对减少,推测更低的温度可能成为了C_(4)植被生长的限制因素。中更新世(约1.0 Ma)以来,黑碳碳同位素比值整体负偏,表明源区C_(4)植被相对丰度减少。尽管沉积物源区在0.8 Ma左右转变为纬度更高的黄河流域,但东亚不同纬度地区记录均显示了碳同位素负偏,表明这是一区域现象,分析认为全球气候变冷是影响中更新世以来C_(4)植被演化的重要因素。本研究揭示出,除了全球性的因素(大气CO_(2)浓度)外,区域气候(温度和干旱度)在东亚地区C_(3)/C_(4)植被长期演化中具有重要影响。Terrestrial vegetation is an important part of the global ecosystem.The C_(3)/C_(4)evolution has great implication for our understanding the response and adaptation mechanisms of ecosystem to global changes.The timing,processes and mechanism of C_(4) plant expansion in East Asia since the Late Pliocene are still controversial.Especially,the evolution history of C_(3)/C_(4)plant in the Yangtze River Basin at the middle latitude and its comparison with plant evolution through different latitude regions of East Asia remains unclear.Here we firstly reported the black carbon record from the Continental Shelf Drilling Program(CSDP)Core CSDP-1(34°18'N,122°22'E;water depth 52.5 m;300.10 m in length and since 3.5 Ma)from the South Yellow Sea drilled by Research Vessel KAN 407 in June 2013,as well as surface sediment samples of seven major rivers in Eastern China.The content,mass accumulation rate(MAR)and carbon isotopic composition of black carbon extracted from sediments of core CSDP-1,were used to reconstruct the C_(3)/C_(4)vegetation evolution in Eastern China since the Late Pliocene.During the Late Pliocene(ca.3.0~2.6 Ma),the carbon isotopic composition of black carbon of the study core shows more positive values,indicating the increased relative abundance of C_(4) plants in the Yangtze River Basin during that period.We suggest that such evolution was possibly controlled by the increased aridity in East Asia and the decline of atmospheric CO_(2)concentration at the Late Pliocene.In contrast,reduced C_(4) vegetation abundance in the midhigh latitude regions(i.e.,the Loess Plateau)in the Late Pliocene likely suggests that lower temperature became the limited factor for growth of C_(4) vegetation.Since the Middle Pleistocene(ca.1.0 Ma),the carbon isotope composition of black carbon at core CSDP-1 reversed to more negative,suggesting that the relative abundance of C_(4) vegetation in the source area declined at that period.Although the sediment source of the study area shifted from the Yangtze River to the Yellow River

关 键 词：C4植被演化 黑碳 干旱 全球变冷 南黄海 晚上新世-更新世 

分 类 号：P593[天文地球—地球化学] P736[天文地球—地质学]