福建三沙湾90 ka以来沉积物来源及环境演变研究  

Sediment sources and environment evolution since 90 ka in Sansha Bay,Fujian Province

作　　者：于俊杰[1] 刘平 林丰增 王继龙 丁大林 彭博[1] 武彬[1] 劳金秀[1] YU Junjie;LIU Ping;LIN Fengzeng;WANG Jilong;DING Dalin;PENG Bo;WU Bin;LAO Jinxiu(Nanjing Center, China Geological Survey, Nanjing 210016,Jiangsu,China;State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China;Ningde Bureau of Natural Resources,Ningde 352100, Fujian, China;School of Communication and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China)

机构地区：[1]中国地质调查局南京地质调查中心,江苏南京210016 [2]华东师范大学河口海岸学国家重点实验室,上海200062 [3]宁德市自然资源局,福建宁德352100 [4]重庆邮电大学通信与信息工程学院,重庆400065

出　　处：《华东地质》2022年第1期30-39,共10页East China Geology

基　　金：中国地质调查局“宁德海岸带陆海统筹综合地质调查(编号:DD20189505)”项目资助。

摘　　要：三沙湾是福建省最大的海湾,也是中国东部典型的基岩半封闭海湾,其冲淤变化受山溪性河流和潮汐输运泥沙量变化影响,明确物源演变特征对于研究湾内沉积演化趋势具有重要意义。以三沙湾NDGK2钻孔为研究对象,在前期地层序列和年代框架研究的基础上,通过重矿物和地球化学特征揭示90 ka以来的物源演变特征,进一步揭示三沙湾在全球气候海平面波动下的环境演变规律。重矿物分析显示:MIS5、MIS3和MIS1高海面阶段以自生矿物为主,锆石含量相对较低,ZTR指数较低;MIS4和MIS2低海面阶段以褐铁矿为主,锆石含量相对较高,ZTR指数较高。主量元素和微量元素地球化学特征显示:MIS5、MIS3和MIS1高海面阶段Ti、Ba、Ni含量相对较高;MIS4和MIS2低海面阶段Ni、Ba含量相对较低。重矿物特征及地球化学指标揭示了90 ka以来高海面阶段悬浮泥沙主要来源于潮流输入的海域泥沙,低海面阶段泥沙主要来源于亚热带气候下以霍童溪为代表的当地河流。相比内陆地区,沉积物物源指标及孢粉组合特征均表明宁德地区对全球降温事件的响应并不敏感,冰期河流仍较发育。轨道时间尺度上,相比陆源物质输入,海平面上升才是三沙湾泥沙淤积的关键影响因素。The Sansha Bay,representing a typical bedrock semi-enclosed bay in eastern China,is the largest bay in Fujian Province.Processes of erosion and accumulation in Sansha Bay are affected by sediment provenance derived from mountainous rivers and tides.Therefore,understanding the characteristic of sediment provenance has critical significance for discussing sedimentary evolution in the bay.In this study,we conduct a heavy minerals and geochemical elements analysis of drilling core NDGK2 obtained from Sansha Bay,reconstruct the evolution history of sediment provenance since approximately 90 ka,based on the published stratigraphic sequence and chronological framework.Under the influence of global climate and sea level changes,sedimentary evolution patterns in Sansha Bay were proposed.The result shows that minerals were dominated by authigenic pyrite with relatively low zircon contents and low ZTR index during the high sea level stages of(marine isotope stage)MIS5,MIS3,MIS1,and were dominated by limonite with relatively high zircon contents and high ZTR index during the low sea level stages of MIS4 and MIS2.Major and trace elements are characterized with obviously high content of Ti,Ba,and Ni during stages MIS5,MIS3 and MIS1 and low Ni and Ba contents during stages MIS4 and MIS2.Both mineral and element proxies suggest that the suspended sediments in the high sea level stages since 90 ka were mainly derived from Yangtze River and probably transported by tidal currents.In contrast,sediments in the low sea level stages consisted of the mixture that was derived from local rivers represented by Huotong River and from Yangtze River.Compared with inland area,the characteristics of sediment provenance and palynological assemblage indicate that Ningde area is not sensitive to global cooling events and rivers are still relatively developed even in the glacial period.On the Earth's orbital scale,a high sea level plays a more substantial role than the terrigenous input in the formation of sedimentary environment.This study provide

关 键 词：重矿物 地球化学 三沙湾 物源 海平面变化 

分 类 号：P67[天文地球—海洋地质]