江汉平原沔城M1孔的沉积特征与古环境重建

通过对江汉平原沔城M₁孔湖泊沉积物进行沉积特征、粒度、14C年代、孢粉分析,重建了晚冰期以来该地区古环境、古气候演化的过程和序列:晚冰期后期有一扩张期,气候温湿并出现湖泊相沉积;晚冰期末期气候温凉偏干、河流环境;全新世初期(10-8.9kaBP),气候转向温湿;全新世大暖期(8.9-3.5kaBP),总体上气候温暖湿润,其中6.8-4.9kaBP是最宜期,4.9-4.8kaBP和4.4-4.2kaBP为两次降温事件,4.8kaBP积水湖盆开始形成,3.9-3.5kaBP为云梦泽鼎盛期;全新世晚期(3.5-1.7kaBP),气温较大暖期有所下降,其中3.5-2.5kaBP温凉偏湿,2.5-1.7kaBP较为温湿,湖泊较为稳定,1.7kaBP开始,云梦泽萎缩,钻孔所在位置出露水面。      

西安何家营全新世黄土磁化率的古气候环境

探讨西安地区全新世以来古气候环境的变化规律,通过西安何家营村全新世黄土剖面的地层岩性描述,运用磁化率年龄模型确定地层年代序列,根据所采样品的磁化率值绘制磁化率曲线来分析全新世气候变化。同时选取其他学者所建立的气候曲线进行对比,将西安地区全新世气候分为5分阶段：10～8．5kaBP,冷暖转换阶段;8．5～7kaBP,大暖期冷暖波动阶段;7～5kaBP,大暖期鼎盛阶段;5～3．4kaBP,大暖期温度波动暖和阶段;3．4kaBP至今,气温先下降后稳定阶段。     

西藏纳木错及邻区全新世气候与环境变化的地质记录

综合分析了全新世期间内的多种与气候和环境变化密切相关的地质记录,结果表明该区全新世期间的气候变化可划分为3个阶段:1)约11.8～8.4kaBP期间,处于微温期和升温期,气候相对温和稍湿.2)8.4～4.0kaBP期间,为全新世气候最适宜时期或大暖期.该期间的平均气温可能比现今高约5℃,降水量比今多100～200mm.3)4.0kaBP以来,气候整体较为干冷.纳木错湖面发生持续下降,其最大下降幅度可达11.4m.冰川进退和湖面波动表明,该期间内的气候波动过程分别与新冰期和小冰期相对应,其中又各包含了3次明显的冷期,其中新冰期期间的最低年平均气温可达-6℃左右.约1970年以来,区域气候向暖湿方向转化,造成念青唐古拉山西布冰川后退约120～200m,纳木错湖面上涨了约2m.     

南海诸岛全新世珊瑚礁演化的特征

本文概括了南海诸岛珊瑚礁的分布,礁体地形、地貌和地质的一般特征,论述了老灰沙岛、新灰沙岛和礁坪等几类典型的全新世珊瑚礁礁体演化的基本过程,讨论了全新世珊瑚礁演化与季风、气候和海平面的关系。礁坪是随着冰后期海平面上升在晚更新世侵蚀面上堆积的,全新世中期高海面出现前后分别形成老灰沙岛和新灰沙岛。     

浑善达克沙地磁化率和有机质揭示的全新世气候变化

根据浑善达克沙地锡林浩特剖面磁化率、有机质等气候代用指标的变化特征和14C测年结果,分析和讨论了浑善达克沙地10.7kaBP以来的气候变化过程.实验数据显示地层剖面磁化率和有机质值的变化趋势基本一致,且峰值段对应古土壤层,谷值段对应风成砂层.依据磁化率和有机质含量的变化将浑善达克沙地全新世气候变化分为5个阶段:10.7～8.5 kaBP,气候相对冷干,冬季风较强,夏季风相对较弱,但有增强趋势;8.5～5.8 kaBP,气候温暖湿润,夏季风较强,冬季风相对较弱,与全新世最适宜期对应;5.8～3.5 kaBP,气候波动变化频繁,但夏季风和冬季风都相对较弱;3.5～1.9 kaBP,气候温暖湿润,仅次于全新世最适宜期,夏季风较强,冬季风相对较弱;1.9 kaBP以来,气候波动渐变冷干,冬季风逐渐波动增强,夏季风相对逐渐减弱.并且其气候变化与全球变化具有较好的一致性.     

11.5kaBP以来尕海沉积物氧化物地球化学特征及其环境意义

通过对柴达木盆地尕海DG03孔沉积序列的年代学测定和沉积物分析,选取对气候环境较为敏感的SiO2,Al2O3,TiO2,Fe2O3,MgO,ＣaO,K2O,Na2O等作为环境代用指标,分析了尕海地区11.5 kaBP以来的气候环境变化。研究表明尕海地区在11.5 kaBP以来存在4个明显的气候变化期:晚冰期晚期（11.5～10.16 kaBP）的气候波动较大,其中11.5～11.16 kaBP是暖干气候;11.16～10.16 kaBP,气候冷干,可能是新仙女木事件的反映;全新世早期（10.16～7.83 kaBP）气候转暖,有短期极干冷事件的发生;中全新世适宜期（7.83～4.73 kaBP）,气候温暖湿润;4.73 kaBP以来的全新世晚期,气候环境明显恶化,期间出现气候暖湿与干冷的多次波动变化。     

大河三角洲全新世海平面研究中的若干重要问题——以长江、尼罗河和密西西比河三角洲为例

本文回顾和总结了不同纬度带大河三角洲全新世相对海平面曲线的特征及影响因素.以相近纬度带的长江、尼罗河与密西西比河三角洲为例,剖析了全新世中期无“高于现代平均海平面”的“壅水”现象,认为直布罗陀海峡、加勒比海岛屿和白令海峡对北极圈南下融水进入地中海、墨西哥湾和西太平洋起到了限制作用.大量的研究还表明,距今约7ka时尼罗河三角洲相对海平面低于现今约14m,而此时密西西比河三角洲相对海平面约为-10m,长江三角洲仅约为-5m;随后,它们的差距逐渐减小,反映了沉降作用对相对海平面变化的影响.论文提出一种利用全新世三角洲沉积层序、结合相对海平面曲线来判断区域沉降差异的方法;总结了三角洲古地形对海平面上升的响应模式,以及利用三角洲新石器遗址“最低居住面”重塑全新世相对海平面变化的路径.这些均为三角洲地区全新世海平面变化与地貌环境演化的相关研究提供了新的前景.     

海南岛沿岸全新世地层与海面变化的初步研究

研究沿海地区全新世沉积特征与形成年代,进行地层划分与对比,恢复沉积环境及演变历史,对探讨海岸线变迁、海平面变化与地壳运动等理论问题,有重要意义。以往,海南岛沿岸全新世沉积与地层的研究比较薄弱,主要涉及珊瑚礁、沿岸砂堤等。     

安徽巢湖湖相地层记录的早全新世气候事件

通过对安徽巢湖西岸杭埠河入口三角洲地区CH孔岩芯湖泊相沉积物的色度、磁化率及地球化学等古环境代用指标的分析与研究,揭示了巢湖地区早全新世时期(11.7~7.5cal.kaBP)的极端气候事件。研究表明:研究区11.7~7.5cal.kaBP期间沉积环境极不稳定,气候波动明显,并分别约在7.8cal.kaBP,8.6cal.kaBP,9.4cal.kaBP,10.5cal.kaBP,11.4cal.kaBP出现5次显著的冷干气候事件,且以8.6cal.kaBP与11.4cal.kaBP表现最为强烈,与我国冰芯、石笋及湖泊沉积物所记录的早全新世冷事件具有可比性,反映了巢湖湖泊沉积物对我国早全新世北半球中纬度地区的季风气候有明显的响应,这将为我国北半球早全新世气候波动的机理研究提供佐证。     

腾格里沙漠西北缘湖泊沉积记录的区域风沙特征

对位于腾格里沙漠西北缘的青土湖QTL01剖面进行了沉积物粒度分析,并利用粒级—标准偏差模型,提取出了对沉积环境变化敏感的粒度组分,60~550 μm粒级含量指示了区域风沙活动的强弱,而<60 μm颗粒含量指示了入湖径流量的变化。结合14C测年结果,探讨了10~2.5 Cal kaBP青土湖地区风沙活动和环境演化特征:10～7.8 Cal kaBP,<60 μm组分含量逐渐增加,指示湖区入湖径流逐渐增多,同时60～550 μm组分含量逐渐减少表明湖区风沙活动逐渐减弱,总体上表明了早全新世该区域环境逐渐转湿;7.8～7.5 Cal kaBP,60～550 μm组分含量几乎占该阶段沉积物的95％以上,表明风沙活动极为强烈,区域非常干旱;7.5～5 Cal kaBP,沉积物中<60 μm、60~550 μm的组分含量相对稳定,且<60 μm组分含量达到了10～2.5 Cal kaBP期间最高值,表明了区域风沙活动较弱,气候环境湿润稳定; 5～2.5 Cal kaBP,<60 μm组分含量逐渐降低,而60～550 μm组分逐渐升高,表明了区域风沙活动逐渐加强,入湖径流逐渐减小,指示了区域干旱化的趋势。     

Late Devensian and Holocene relative sealevel changes at Loch nan Eala,near Arisaig,northwest Scotland

Pollen, diatom, radiocarbon and lithostratigraphical data from isolation basins in northwest Scotland are used to quantify the reference water (tide) level, indicative range and age of differenty types of isolation and connection contacts. Tendencies of sea-level movement and relative sea-level changes from the mid-Lateglacial Interstadial (11.8 ka BP) to the late Holocene are constructed from these data. Relative sea-level fell continuously from + 17.8 m OD at 11.8 ka BP to ca. + 5.2 m OD at 10.1 ka BP. From an unkown minimum between 10 ka and 9 ka BP relative sea-level then rose to +6.3 m OD at 8.3 ka BP. The maximum Holocene sea-level occurred within the range +6.6 m OD to +9.3 m OD between 6.6 ka BP and 4.0 ka BP before falling to present. Isobase, age-altitude and quantitative rebound models for northwest Scotland are tested using these sealevel data, but none of the published models shows close agreement with the new results.     

苏拉威西海周边地区全新世植被演化及气候变化

全新世时期的环境和气候变化是全球气候模拟、预测中不可或缺的资料.对苏拉威西海西北部MD98-2178孔(3.6200°N,118.7000°E,水深1 984 m)全新世的样品进行孢粉分析和浮游有孔虫氧稳定同位素测试,重建全新世苏拉威西海周边地区植被演化和气候变化图景.根据孢粉记录得到:在全新世早期至7 ka BP时,各孢粉组合浓度剧烈下降,指示海平面处于上升阶段;在7~4 ka BP时,各孢粉组合浓度都处于低谷,体现为高海平面期;在4 ka BP之后,孢粉记录则显示海平面有小幅的下降.在全新世中期,即5~4 ka BP,热带高山雨林花粉含量明显上升,表明是温度低值期.蕨类孢子记录显示降雨量在全新世早期是持续增加的,但在全新世中期之后,降雨量有所减少,这与陆地孢粉记录和印尼石笋记录的结果相似,体现全新世该地区降雨量受海陆格局和太阳活动共同影响.      

渤海湾西岸CZ01钻孔沉积物粒度端元分析及其气候—海平面变化响应*

沧州地区位于海陆交互的渤海湾西岸,易受到海平面变化和极端气候事件的影响,对于全球气候变化的响应十分敏感。应用非参数化端元分析模型将沧州地区CZ01钻孔中更新世晚期以来的沉积物粒度划分出6个端元并分析其物源,结合已有地质记录,揭示不同时间尺度下各端元对气候—海平面变化的响应。结果表明: (1)EM1(5.01 μm)主要为远源的风尘输入,EM2(13.18 μm)和EM3(39.81 μm)为古黄河所携带的沉积物,EM4(69.18 μm)和EM5(138.04 μm)为海相沉积物,EM6(275.42 μm)可能指示古洪水等极端气候事件。(2)深海氧同位素(MIS)Ⅰ 阶段,气候温暖湿润,EM4+5含量指示渤海海平面整体呈波动上升的趋势并逐渐接近现代海平面。该阶段内由于11.5 ka BP左右的新仙女木事件以及5.1 ka BP左右冷干事件的发生,渤海海平面在稳定上升状态后出现停滞或小幅下降的现象; 而在9.5 ka BP、7.5 ka BP、5.8 ka BP和1.7 ka BP左右,东亚夏季风增强导致降水增加,渤海海平面升高。(3)MIS Ⅵ 阶段北半球气候冷干,150~132 ka BP左右因喜马拉雅运动减弱造成的区域沉降中心转移致使渤海海面升高。MIS Ⅴ 阶段气候波动剧烈: 在间冰期暖期(5a、5c和5e)气候暖湿,渤海海平面上升; 而MIS5b和5d时期渤海海面高度较低。MIS Ⅳ 阶段较MIS5a末期海平面突然下降后趋于稳定,期间出现若干次小规模海侵事件,可能与东亚夏季风频繁变化有关。MIS Ⅲ 阶段至末次冰盛期海平面大幅度下降且存在周期性升降变化,并在46 ka BP左右出现大规模海侵事件。MIS Ⅱ 阶段较MIS Ⅲ 阶段海平面出现小幅度下降,为低海平面时期; 伴随15 ka BP左右冰盛期的结束,东亚夏季风增强,海平面开始上升。渤海海平面180 ka BP以来的变化记录与北半球乃至全球范围内的地质记录存在一致性,与太阳辐射波动引起的冰川消融及东亚夏季风变化密切相关。     

中全新世福建沿海地区海平面波动：基于NDQK5岩芯介形类化石记录

福建沿海地区第四系较为发育,是研究晚更新世以来相对海平面变化的理想区域。本文以福建宁德NDQK5岩芯中产出的高分辨率介形类化石为研究对象,结合加速器质谱法(accelerator mass spectrometry, AMS)14C和光释光测年技术建立岩芯年代框架,重建了中全新世期间福建沿海地区的相对海平面变化。结果显示,NDQK5岩芯中的介形类化石记录主要分布于4~17. 1 m段,对应年代约为8. 2~6. 9 ka BP。岩芯内共计识别出海相介形类23属26种,根据优势种以及特征种的相对丰度变化特征可将岩芯内的介形类动物群划分为3个组合：① 介形类组合A以Bicornucythere bisanensis和Sinocytheridea impressa为主,代表潮下带环境;② 介形类组合B以Sinocytheridea impressa和Neomonoceratina delicata为优势种,指示近岸内陆架的沉积环境;③ 介形类组合C以Sinocytheridea impressa和Loxoconcha ocellifera为主,代表潮间带的沉积环境。基于介形类组合的分布特征,本文推断福建沿海地区海平面约在8. 2~7. 4 ka BP期间持续上升,并在约7. 9~7. 4 ka BP区间达到最高;7. 4~7. 0 ka BP期间海平面下降,随后再次上升。因此,介形类化石记录指示福建沿海地区在全新世高海平面背景下依然存在相对海平面的次一级波动。同时,结合已有福建沿海地区海平面变化驱动机制的研究结果,本研究推断8. 2~7 ka BP期间福建沿海地区的海平面变化可能主要受控于冰盖融水;7 ka BP后该地区的海平面波动可能受控于“冰川- 水均衡调整”作用。     

东海陆架全新统高分辨率层序地层学研究

在高分辨率１４Ｃ测年、岩石、生物、化学、同位素、气候及磁性地层学研究成果基础上,通过不同沉积背景典型钻孔的沉积学分析,运用层序地层学理论,对东海陆架全新统进行了高分辨率层序划分及对比;建立了全新世层序地层格架及海平面变化过程;提出了相应的层序成因模式。研究结果表明,东海陆架全新统相当于一个发育中的六级（１～１０ｋａ）层序,可进一步划分为３个七级（０．１～１ｋａ）层序和若干个更次级层序。代表１个六级或３个七级周期相对海平面变化过程中叠加有若干更次级的海平面波动,它们与地球旋回谱系中的太阳带、历法带密切相关。七级层序具有与三级层序相近的内部构型和成因格架。在东海陆架全新世沉积演化过程中,长江三角州至少有３次不同程度地越过东海陆架进入冲绳海槽,并滞留有至少３层海侵改造“残积砂”沉积。在东海陆架全新世海平面变化期间,最大海平面时期为约距今６～５ｋａ,大致高于现今海平面２～４ｍ,最低海平面在距今１０ｋａ左右,大约低于现今海平面１３０ｍ。目前,由于温室效应的影响,海平面仍呈小幅度波浪式上升。事实证明,层序地层学不仅丰富了现代海洋沉积学的内容,而且解决了许多海洋沉积学未能解决的问题。     

Holocene relative sea level changes in the Västervik-Gamlebyviken region on the southeast coast of Sweden,southern Baltic Sea

We reconstruct the Holocene shore displacement of the Västervik-Gamlebyviken area on the southeast coast of Sweden, characterised by a maritime cultural landscape and archaeological significance since the Mesolithic. Sediment cores were retrieved from four lake basins that have been raised above sea level due to the postglacial land uplift and eustatic sea level changes after the melting of the Fennoscandian Ice Sheet. The cores were radiocarbon dated and analysed for loss on ignition and diatoms. The isolation thresholds of the basins were determined using LiDAR data. The results provide evidence for the initiation of the first Littorina Sea transgression in this area at 8.5 thousand calibrated years before present (cal. ka BP). A relative sea level rise by ∼7 m a.s.l. is recorded between 8.0 and 7.5 cal. ka BP with a highstand at ∼22 m a.s.l. between 7.5 and 6.2 cal. ka BP. These phases coincide with the second and third Littorina Sea transgressions, respectively, in the Blekinge area, southern Sweden and are consistent with the final deglaciation of North America. After 6.2 cal. ka BP, the relative sea level dropped below 22 m a.s.l., and remained at ∼20 m a.s.l. until 4.6 cal. ka BP coinciding with the fourth Littorina Sea transgression in Blekinge. From 4.6 to 4.2 cal. ka BP, the shore displacement shows a regression rate of 10 mm a⁻¹ followed by a slowdown with a mean value of 4.6 mm a⁻¹ until 1.6 cal. ka BP, when the relative sea level dropped below 3.3 m a.s.l. The Middle to Late Holocene highstand and other periods of minor sea level transgressions and/or higher salinity between 6.2 and 1.7 cal. ka BP are attributed to a combination of warmer climate and higher inflow of saline waters in the southern Baltic Sea due to stronger westerlies, caused by variations in the North Atlantic atmospheric patterns.     

MIS 3以来浙江温瑞平原YQ0902孔古环境与古气候变化记录*

YQ0902孔位于浙江南部瓯江三角洲南侧温瑞平原上。沉积相、粒度分析以及AMS ¹4C测年数据表明,硬土层之下为海洋氧同位素3阶段(MIS 3）形成的潟湖相沉积,据此推测MIS 3高海平面至少达到现今海平面之下30m左右(未经构造升降和沉积物压实作用等影响的校正,下同）。硬土层的成土过程发生于MIS 2,其母质部分为MIS 3的潟湖沉积,部分为河漫滩沉积。硬土层之上是一套形成于全新世的海侵—海退旋回,与长江三角洲南翼前缘的沉积相组合类似。研究钻孔初始海泛面约形成于9 cal ka BP,推算当时的海平面约低于现今海平面25 m。中全新世最大海侵前后,东亚季风较强,通过径流或沿岸流输入本区的沉积物较充足,沉积速率较大。随着海平面相对稳定或略有下降,东亚季风减弱,可容空间减小,中晚全新世(5～2 cal ka BP）沉积速率较低。高分辨率的XRF岩心扫描获得的元素相对含量是古环境与古气候研究的重要指标,其中Cl/Ti、Fe/Ti值可分别作为海相性(与海洋联通程度）与东亚季风强弱的替代指标。     

Submarine and onshore end moraines in southern Newfoundland: implications for the history of late Wisconsinan ice retreat

Recessional positions of the Newfoundland ice sheet 14-9 ka BP are represented by fjord-mouth submarine moraines, fjord-head emerged ice-contact marine deltas, and inland moraine belts. The arcuate submarine moraines have steep frontal ramparts and comprise up to 80 m of acoustically incoherent ice-contact sediment (or till) interfingered distally with glaciomarine sediment that began to be deposited c. 14.2 ka BP. The moraines formed by stabilization of ice that calved rapidly back along troughs on the continental shelf. The ice front retreated to fjord-heads and stabilized to form ice-contact delta terraces declining in elevation westward from +26 m to just below present sea level. Stratified glaciomarine sediments accumulated in fjords, while currents outside fjords eroded the upper part of the glaciomarine deposits, forming an unconformity bracketed by dates of 12.8 and 8.5 ka BP. The delta terraces are broadly correlated with the 12.7 ka BP Robinson's Head readvance west of the area. The ice front retreated inland, pausing three or four times to form lines of small bouldery stillstand moraines, heads of outwash, sidehill meltwater channels, and beaded eskers. Lake-sediment cores across this belt yield dated pollen evidence of three climatic reversals to which the moraines are equated: the Killarney Oscillation c. 11.2 ka BP, the Younger Dryas chronozone 11.0-10.4 ka BP, and an unnamed cold event c. 9.7 ka BP. Relative sea level fell in the early Holocene because of crustal rebound, so that outwash and other alluvium accumulated in deltas now submerged due to relative sea-level rise.     

Depositional environment of the Laptev Sea (Arctic Siberia) during the Holocene

The Holocene depositional setting of the Laptev Sea was studied using three marine sediment cores from water depths between 77 and 46 m. Based on sedimentary parameters (TOC content, δ¹³C_org, sedimentation rates) controlled by radiocarbon age models the palaeoenvironment of a strongly coupled river-shelf system was reconstructed since ˜11 ka BP. Caused by a transgressing sea after the last glaciation, all cores reveal progressive decreases in sedimentation rates. Using the sedimentary records of a core from the Khatanga-Anabar river channel in the western Laptev Sea, several phases of change are recognized: (1) an early period lasted until ˜10 ka BP characterized by an increased deposition of plant debris due to shelf erosion and fluvial runoff; (2) a transitional phase with consistently increasing marine conditions until 6 ka BP, which was marked at its beginning near 10 ka BP by the first occurrence of marine bivalves, high TOC content and an increase in δ¹³C_org; (3) a time of extremely slow deposition of sediments, commencing at ˜6 ka BP and interpreted as Holocene sea-level highstand, which caused a southward retreat of the depositional centres within the now submerged river channels on the shelf; (4) a final phase with the establishment of modern conditions after ˜2 ka BP.     

Isolation basin stratigraphy and Holocene relative sea-level change on Arveprinsen Ejland,Disko Bugt,West Greenland

This paper presents the results of an investigation into Holocene relative sea-level (RSL) change, isostatic rebound and ice sheet dynamics in Disko Bugt, West Greenland. Data collected from nine isolation basins on Arveprinsen Ejland, east Disko Bugt, show that mean sea level fell continuously from ca. 70 m at 9.9 ka cal. yr BP (8.9 ka ¹⁴C yr BP) to reach a minimum of ca. −5 m at 2.8 ka cal. yr BP (2.5 ka ¹⁴C yr BP), before rising to the present day. A west–east gradient in isostatic uplift across Disko Bugt is confirmed, with reduced rebound observed in east Disko Bugt. However, RSL differences (up to 20 m at 7.8 ka to 6.8 ka cal. yr BP (7 ka to 6 ka ¹⁴C yr BP)) also exist within east Disko Bugt, suggesting a significant north–south component to the area’s isostatic history. The observed magnitude and timing of late Holocene RSL rise is not compatible with regional forebulge collapse. Instead, RSL rise began first in the eastern part of the bay, as might be expected under a scenario of crustal subsidence caused by neoglacial ice sheet readvance. The results of this study demonstrate the potential of isolation basin data for local and regional RSL studies in Greenland, and the importance of avoiding data compilations from areas where the isobase orientation is uncertain. Copyright © 1999 John Wiley & Sons, Ltd.