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1.
Yang Yongliang Liu Zhenxia Shen Chengde Li Tiegang Shi Xuefa Cheng Zhenbo Xiong Yingqian 《第四纪研究》2012,32(3)
文章讨论了末次冰期及全新世以来冲绳海槽中部偏东处的沉积物岩芯Z14-6中10Be的历史记录,并与冲绳海槽北部钻孔DGKS9603的10Be记录进行对比.重力柱状岩芯Z14-6取于冲绳海槽水下739m( 27°07'N,127°27′E),全长8.96m.选取了晚更新世末次冰期和全新世的层段(2～175cm,年代跨度为0.37 ～29.3kaB.P.)中12个层位,利用加速器质谱法测定了10Be的含量.Z14-6孔10Be的平均含量为6.10×108atoms/g,最高值(8.71×108atoms/g)出现在6.3kaB.P.层位,末次冰期10Be含量总体上处于低值.与DGKS9603孔(28°08.869′N,127°16.238′E;永深1100m,岩芯长585cm)的数据比较,Z14-6孔中10Be含量普遍较低.Z14-6孔的10Be沉积通量平均值为1.04×109 atoms/cm2 · ka.最高值(1.36× 109atoms/cm2·ka)出现在6.3kaB.P.层位,最低值(6.45×10s atoms/cm2·ka)出现在9.27kaB.P.层位.Z14-6孔所处水深较浅,黑潮流在末次冰期时并未流经Z14-6孔海区,所以其10Be沉积通量只相当于10Be的大气平均生产率( 1.21 ×109 atoms/cm2 ·ka).Z14-6孔中10Be沉积通量降低可能与几个低温事件有关,Z14-6孔在约3kaB.P.和9kaB.P.存在10Be通最减弱现象,因此推测黑潮产生较大变动.Z14-6孔在全新世一些时段的10Be沉积通量峰值显著高于末次冰期时的沉积通量峰值,表明当时黑潮对该海域已发生影响. 相似文献
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利用气相色谱(GC)和气相色谱/同位素比值质谱(GC/IRMS)对东海近岸泥质区、济州岛西南泥质区和冲绳海槽北部表层沉积物中正构烷烃的单体碳同位素组成及分布进行了分析。结果显示东海不同泥质区典型海洋藻类源正构烷烃C19同位素组成基本相似,在-27.4 ‰ ~-28.0 ‰ 之间,平均为-27.7 ‰ 。典型海洋水生植物源C23同位素组成在-28.5 ‰ ~-31.6 ‰ 之间,平均为-30.5 ‰ ,碳同位素组成从近岸泥质区到冲绳海槽北部逐渐变重,表明海槽区与陆架区海洋水生植物种类有所不同。陆架区长链正构烷烃(C25~C31)部分随着碳数的增加,其同位素组成逐渐变轻,但海槽区这一变化不大,显示陆架区的陆源高等植物蜡具有相似的物源,而冲绳海槽北部由于黑潮主干区和黑潮分支(对马暖流)对陆架沉积物进入深海的控制性阻隔作用,其物源与陆架区区别较大。现代输入东海的陆源植物以C3植物为显著优势,C3植物对近岸泥质区北部、近岸泥质区南部、远端济州岛西南泥质区和冲绳海槽北部陆源植物的贡献分别为83 % ,95 ％,75 % 和70 % 。 相似文献
3.
宇宙成因核素10 Be(半衰期1.5Ma)不但是古环境变化的示踪剂,而且具有确定地质年龄的能力。80个全岩样品的10 Be和化学分析数据表明,黄土高原约6Ma以来的红粘土和黄土序列中年龄校正的10 Be浓度与沉积物粒度和风化程度的化学指标具有显著的关系。根据这种关系建立的10 Be浓度与化学指标的经验回归线性模型,可以估计红粘土和黄土形成时的10 Be浓度,确定红粘土和黄土形成的10 Be放射性年龄。 相似文献
4.
暴露测年样品中26Al和10Be分离及其加速器质谱测定 总被引：4，自引：4，他引：0
在已有实验流程基础上,建立并优化了石英样品中Be和Al提取、纯化等实验流程,设计的流程条件实验包括实验试剂、器皿和离子交换柱选择、离子交换树脂分离Be和Al时酸浓度选择等。结果表明,选择钢铁研究总院研制的9Be标准溶液作为10Be样品制备的载体;使用一次性实验器皿;选用4 cm规格的离子交换柱;用0.05 mol/L草酸和0.75 mol/L盐酸混合溶液洗脱吸附于阴离子树脂上的Al,可有效提取、纯化样品中的Be和Al。加速器质谱(AMS)测量结果显示,13组化学空白的10Be/9Be和26Al/27Al比值平均值分别为7.48×10-15和1.96×10-15,与国内已有宇宙成因核素实验室的结果(5×10-15~8×10-15)具有可比性。电感耦合等离子体发射光谱(ICP-AES)的测量结果表明,Be、Al回收率分别达90%和60%。基于新建立的实验流程分析了祁连山北侧金佛寺的一个岩石样品,获得了10Be和26Al的暴露年代分别为(10.7±1.0) ka和(10.0±1.2) ka,与前人研究结果一致。 相似文献
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主要讨论宇宙射线成因核素10Be（T 1/2＝ 1．5Ma）在大洋边缘海洋学尤其是中国近海海洋研究中的应用。在过去的近20年中，在中国开展的10Be研究在黄土堆积年龄及地层对比方面获得了诸多成果，但在海洋方面的应用研究距国际水平仍有一定的差距，尚需进一步加强。综述了海洋环境中10Be作为一个地球化学示踪剂的研究现状，着重介绍10Be在中国东部海域的收支平衡模式以及讨论10Be在太平洋西部边缘海及岛弧地区的应用前景。 相似文献
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青藏高原若干地点的第四纪冰川年代学* ——深切怀念孙殿卿院士 总被引：1，自引：1，他引：1
赵志中 钱方 刘宗秀 田国强 李名则 苗琦 谭征兵 J.M.Schaefer P.Oberholzer S.Strasky Ch.Schlüechter 吴锡浩 《第四纪研究》2007,27(5):669-673
青藏高原第四纪冰川时空演化问题广受关注。应用宇宙成因核素暴露年龄测定方法开展高原古冰川的年代学研究,对青藏高原聂拉木、唐古拉山、义敦海子山和折多山等4个地区的第四纪冰碛物进行了\{10 Be\},26 Al和21 Ne暴露年龄测定,获得了青藏高原不同地点第四纪冰川发育的年代学数据,结果表明青藏高原出现了多期第四纪冰期,分别为YD事件、末次冰期晚阶段、末次冰期早阶段、倒数第2次冰期和倒数第3次冰期。 相似文献
7.
DSDP519钻孔10Be测定结果表明，在B／M，M／G两地磁极性倒转期间，10Be产生率均约增加20％。DSDP519孔δ10Be曲线与DSDP502孔δ18O曲线具有明显的正相关关系。CT85－5钻孔10Be曲线在34000±3000aB．P存在明显的峰，峰值比正常值高出2．5倍，9Be，Zn变化曲线中均未观察到此峰，与Vostok冰芯10Be峰在时间上属于同期。这进一步说明了此时期内10Be浓度增加是全球性的，只能归因于10Be产生率的增加。Raisbeck峰讯号可以成为某些储存库精确时标。 相似文献
8.
东海与黑潮海水中宇宙射线成因核素10Be的研究 总被引：1，自引：0，他引：1
讨论了中日东海MASFLEX合作计划中调查的东海及冲绳海槽海水中溶解态10Be浓度水平及垂直剖面的结果，在这个海区，影响10Be浓度的因素主要有生物生产力，悬浮颗粒物的再溶解，以及长江水与黑潮水的混合程度。在样品采集期间（夏季和秋季），东海水柱呈分层状态，通常10Be的垂直剖面可以分成三层，即表面混合层，10Be释放层和底层，表层水10Be的浓度众长江口到黑潮逐渐增大，在黑潮的边缘则剧烈增大，10Be的垂直分布表明，在夏季10Be富集在长江口附近和大陆架中部的底层水中，这两个富集海区是分开的，很可能是由大陆沿岸水所隔开，在秋季，10Be在底层水中的富集仅仅出现在东海大陆架的西部，这个现象是和受季风影响的东海海流的变化相一致的，黑潮分支在台湾东北外海向东海南部侵入对10Be的影响要比黑潮主干流本身更加重要显著，由箱式模型所得到的10Be质量平衡计算结果表明，来自黑潮的10Be输入要比长江及大气沉降的输入更为重要，输入东海的10Be大约81％进入到沉积物中，而19％的10Be则通过海流和水交换流出东海，在东海的10Be沉积通量是10Be全球平均大气生产率的5倍左右，因而东海是10Be的一个重要汇集地。 相似文献
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充分认识元素和同位素在不同环境条件下的地球化学行为,是运用元素和同位素示 踪环境变化的前提。对来自于黄土高原的黄土、古土壤和红粘土样品的宇宙成因核素10Be测量和化学成分分析,以及各种化学淋溶实验表明：10Be主要以吸附状态赋存于粉尘沉积物粘粒矿物的表面,部分已结合进自生的粘土矿物中;在粉尘沉积物风化过程中10Be与9Be和～的活动性相似,基本没有发生迁移,其原因是连续沉积的粉尘含有大量的碱性物质,阻止了…Be的解吸附和淋滤;沉积和风化作用导致了10Be浓度与化学指标在黄土-古土壤和红粘土剖面中的协同变化。 相似文献
11.
基于AMS14C测年、有机碳、氮含量及其同位素等指标分析,探讨了冲绳海槽中南部OKT-3孔末次冰消期以来沉积物有机质来源及其对古海洋环境演化的响应。结果显示,OKT-3孔沉积物中有机质主要由中国大陆和中国台湾等陆源有机质,以及海洋自生有机质组成。末次冰消期至全新世晚期（17.3~4 ka B.P.）,中国大陆源有机质贡献逐渐下降,中国台湾源有机质贡献逐渐上升,表明海平面变化、黑潮变动是该阶段有机质来源的主要控制因素。4~1.5 ka期间,陆源有机质供给变化趋势与黑潮变动不一致,表明该时期陆源输入非黑潮单一控制,还可能受季风降雨等变化影响。值得注意的是,OKT-3孔海源有机质贡献在B-A和PB时期高、YD时期低,与北太平洋地区的生产力变化相似,反映了北太平洋中层水（NPIW）对海水表层生产力的控制作用,NPIW是连通冲绳海槽与北太平洋的重要纽带。 相似文献
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基于有孔虫AMS14C年龄年代框架,通过冲绳海槽中南部的OKT12孔沉积物黏土矿物的分析,探讨了16 ka以来冲绳海槽细颗粒沉积物的物源变化及其对源区气候的响应。研究结果显示,10 ka时黏土矿物组成发生明显变化,伊利石、绿泥石含量增加,高岭石、蒙皂石含量减少,指示物源由之前的长江和东海陆架源转变为台湾源。受到海平面上升影响,长江河口和冲绳海槽距离增加,夏季风增强,黑潮增强,既搬运台湾来源物质,又阻碍长江物质跨陆架输运,在这些因素综合作用下,长江物质减少、台湾物质增加。高岭石/（伊利石+绿泥石）和绿泥石/（伊利石+蒙皂石）比值在4 ka以来增加指示全新世晚期台湾源区侵蚀强度发生变化。4 ka前后物源判别显示,OKT12孔沉积物来源由台湾东北部河流变为台湾东南部河流,反映了该时期季风降雨导致源区台湾不同区域的侵蚀差异,可能与ITCZ南移、ENSO活动增强有关。 相似文献
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The Alps play a pivotal role for glacier and climate reconstructions within Europe. Detailed glacial chronologies provide important insights into mechanisms of glaciation and climate change. We present 26 10Be exposure dates of glacially transported boulders situated on moraines and ice‐moulded bedrock samples at the Belalp cirque and the Great Aletsch valley, Switzerland. Weighted mean ages of ～10.9, 11.1, 11.0 and 9.6 ka for the Belalp, on up to six individual moraine ridges, constrain these moraines to the Egesen, Kartell and Schams stadials during Lateglacial to early Holocene times. The weighted mean age of ～12.5 ka for the right‐lateral moraine of the Great Aletsch correlates with the Egesen stadial related to the Younger Dryas cooling. These data indicate that during the early Holocene between ～11.7 and ～9.2 ka, glaciers in the Swiss Alps seem to have been significantly affected by cold climatic conditions initiated during the Younger Dryas and the Preboreal Oscillation. These conditions resulted in glacier margin oscillations relating to climatic fluctuations during the second phase of the Younger Dryas – and continuing into Boreal times – as supported by correlation of the innermost moraine of the Belalp Cirque to the Schams (early) Holocene stage. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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全新世冲绳海槽北部表层海水温度和初级生产力对黑潮变迁的响应 总被引：2，自引：1，他引：1
在冲绳海槽北部B-3GC孔高分辨率地层年代框架的基础上,利用多种分子生物标志物和生源组分指标,重建了该地区全新世以来表层海水温度和生产力的变化历史.研究发现,U37K-表层海水温度和生产力的变化指示了全新世黑潮及对马暖流分支的变迁.10.6～7.3 ka BP期间,冲绳海槽北部主要受东海陆架冷水团影响,陆源物质输入量增加,初级生产力比较高,表层海水温度较低.7.3～4.6 ka BP期间,黑潮暖流对该区的影响迅速增强,表层海水快速增温,陆源物质输入减少,但是各种生产力指标显示出上升趋势,与该区上升流的出现和迅速发育有关.4.6～2.7 ka BP期间,即全新世普林虫低值事件(PME)期间,表层海水温度明显降低了0.8～1.4℃,陆源物质输入增加,初级生产力和各种生源组分的含量也达到较高水平,说明此时黑潮强度减弱,或者黑潮主流轴向太平洋方向发生偏移,该区再次受到陆架冲淡水的影响.2.7 ka BP以来,虽然黑潮暖流再次影响到该海区,但初级生产力和生源物质输出量继续大幅增高,可能与该地区上升流的持续发育有关. 相似文献
15.
Landslide deposits as stratigraphical markers for a sequence‐based glacial stratigraphy: a case study of a Younger Dryas system in the Eastern Alps 
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下载免费PDF全文 Mathias G. Bichler Martin Reindl Jürgen M. Reitner Ruth Drescher‐Schneider Christian Wirsig Marcus Christl Irka Hajdas Susan Ivy‐Ochs 《Boreas: An International Journal of Quaternary Research》2016,45(3):537-551
Detailed 10Be and 14C dating and supporting pollen analysis of Alpine Lateglacial glacial and landslide deposits in the Hohen Tauern Mountains (Austria) constrain a sequence‐based stratigraphy comprising a major landslide (13.0±1.1 ka) overlain by till and termino‐lateral moraines of an advancing (12.6±1.0 ka) and retreating (11.3±0.8 ka) glacier in turn overlain by a minor landslide (10.8±1.1 ka). These results define glacier activity during the Younger Dryas age Egesen stadial bracketed by landslide activities during the Bølling‐Allerød interstadial and the Preboreal. In contrast to recent studies on Holocene glaciation in the Alps, no traces of any Holocene glacier advance bigger than during the Little Ice Age are documented. Furthermore, this study demonstrates the advantages of using an allostratigraphical approach based on unconformity‐bounded sedimentary units as a tool for glacial stratigraphy in formerly glaciated mountain regions, rather than a stratigraphy based on either isolated morphological features or lithostratigraphical characteristics. 相似文献
16.
Stefan Strasky Angela A. Graf Zhizhong Zhao Peter W. Kubik Heinrich Baur Christian Schlüchter Rainer Wieler 《Journal of Asian Earth Sciences》2009,34(3):458-465
The sensitivity of Tibetan glacial systems to North Atlantic climate forcing is a major issue in palaeoclimatology. In this study, we present surface exposure ages of erratic boulders from a valley system in the Hengduan Mountains, southeastern Tibet, showing evidence of an ice advance during Heinrich event 1. Cosmogenic nuclide analyses (10Be and 21Ne) revealed consistent exposure ages, indicating no major periods of burial or pre-exposure. Erosion-corrected (3 mm/ka) 10Be exposure ages range from 13.4 to 16.3 ka. This is in agreement with recalculated exposure ages from the same valley system by [Tschudi, S., Schäfer, J.M., Zhao, Z., Wu, X., Ivy-Ochs, S., Kubik, P.W., Schlüchter, C., 2003. Glacial advances in Tibet during the Younger Dryas? Evidence from cosmogenic 10Be, 26Al, and 21Ne. Journal of Asian Earth Sciences 22, 301–306.]. Thus this indicates that local glaciers advanced in the investigated area as a response to Heinrich event 1 cooling and that periglacial surface adjustments during the Younger Dryas overprinted the glacial morphology, leading to deceptively young exposure ages of certain erratic boulders. 相似文献
17.
Takahiro Watanabe Toshio Nakamura Fumiko Watanabe Nara Takeshi Kakegawa Kazuho Horiuchi Ryoko Senda Takefumi Oda Mitsugu Nishimura Genki Inoue Matsumoto Takayoshi Kawai 《Quaternary International》2009,205(1-2):12
High-time resolution 14C dating of Lake Baikal sediment cores indicates negative and positive anomalies of calculated linear sedimentation rate (LSR; 1.1 and 35.6 cm/ka, respectively) during the period of climate transition from the last glacial to Holocene. The timing of the Lake Baikal apparent LSR anomalies is consistent with that of the changes in the atmospheric radiocarbon concentration (Δ14C) during Younger Dryas rapid cooling event. 14C dating of lipids in the Lake Baikal surface sediments revealed that the sources of sedimentary lipids were different in each basin. In the Northern Basin of Lake Baikal, the 14C age of total lipids from the surface sediment (4.0 14C ka) was found to be older than that of TOC (1.6 14C ka). By contrast, the 14C age of total lipids in the Southern Basin was younger than that of the TOC by ca. 0.7–3.0 ka.In the Lake Hovsgol sediment cores, ages of the main lithologic boundaries during the last glacial–interglacial transition were estimated based on new 14C data sets. TOC concentration in the cores started to rapidly increase at 13.8 ± 0.3 14C ka at the base of the basinwide finely laminated layer deposited during Bølling/Allerød. The base of the layer diatomaceous mud corresponds to the end of Younger Dryas event (10.6 ± 0.1 14C ka). 相似文献
18.
Susan Ivy-Ochs Hanns Kerschner Max Maisch Marcus Christl Peter W. Kubik Christian Schlüchter 《Quaternary Science Reviews》2009,28(21-22):2137-2149
In the Alps, climatic conditions reflected in glacier and rock glacier activity in the earliest Holocene show a strong affinity to conditions in the latest Pleistocene (Younger Dryas). Glacier advances in the Alps related to Younger Dryas cooling led to the deposition of Egesen stadial moraines. Egesen stadial moraines can be divided into three or in some cases even more phases (sub-stadials). Moraines of the earliest and most extended advance, the Egesen maximum, stabilized at 12.2 ± 1.0 ka based on 10Be exposure dating at the Schönferwall (Tyrol, Austria) and the Julier Pass-outer moraine (Switzerland). Final stabilization of moraines at the end of the Egesen stadial was at 11.3 ± 0.9 ka as shown by 10Be data from four sites across the Alps. From west to east the sites are Piano del Praiet (northwestern Italy), Grosser Aletschgletscher (central Switzerland), Julier Pass-inner moraine (eastern Switzerland), and Val Viola (northeastern Italy). There is excellent agreement of the 10Be ages from the four sites. In the earliest Holocene, glaciers in the northernmost mountain ranges advanced at around 10.8 ± 1.1 ka as shown by 10Be data from the Kartell site (northern Tyrol, Austria). In more sheltered, drier regions rock glacier activity dominated as shown, for example, at Julier Pass and Larstig valley (Tyrol, Austria). New 10Be dates presented here for two rock glaciers in Larstig valley indicate final stabilization no later than 10.5 ± 0.8 ka. Based on this data, we conclude the earliest Holocene (between 11.6 and about 10.5 ka) was still strongly affected by the cold climatic conditions of the Younger Dryas and the Preboreal oscillation, with the intervening warming phase having had the effect of rapid downwasting of Egesen glaciers. At or slightly before 10.5 ka rapid shrinkage of glaciers to a size smaller than their late 20th century size reflects markedly warmer and possibly also drier climate. Between about 10.5 ka and 3.3 ka conditions in the Alps were not conducive to significant glacier expansion except possibly during rare brief intervals. Past tree-line data from Kaunertal (Tyrol, Austria) in concert with radiocarbon and dendrochronologically dated wood fragments found recently in the glacier forefields in both the Swiss and Austrian Alps points to long periods during the Holocene when glaciers were smaller than they were during the late 20th century. Equilibrium line altitudes (ELA) were about 200 m higher than they are today and about 300 m higher in comparison to Little Ice Age (LIA) ELAs. The Larstig rock glacier site we dated with 10Be is the type area for a postulated mid-Holocene cold period called the Larstig oscillation (presumed age about 7.0 ka). Our data point to final stabilization of those rock glaciers in the earliest Holocene and not in the middle Holocene. The combined data indicate there was no time window in the middle Holocene long enough for rock glaciers of the size and at the elevation of the Larstig site to have formed. During the short infrequent cold oscillations between 10.5 and 3.3 ka small glaciers (less than several km2) may have advanced to close to their LIA dimensions. Overall, the cold periods were just too short for large glaciers to advance. After 3.3 ka, climate conditions became generally colder and warm periods were brief and less frequent. Large glaciers (for example Grosser Aletschgletscher) advanced markedly at 3.0–2.6 ka, around 600 AD and during the LIA. Glaciers in the Alps attained their LIA maximum extents in the 14th, 17th, and 19th centuries, with most reaching their greatest LIA extent in the final 1850/1860 AD advance. 相似文献
19.
Deborah C. McCormack Simon H. Brocklehurst Duncan H.B. Irving Derek Fabel 《第四纪科学杂志》2011,26(1):97-108
Cosmogenic 10Be surface exposure ages for bedrock sites around Torridon and the Applecross Peninsula in Wester Ross, northwest Scotland, provide new insights into the Lateglacial transition. Accounting for postglacial weathering, six statistically comparable exposure ages give a late Younger Dryas (G‐1) exposure age of 11.8 ± 1.1 ka. Two further outliers are tentative pre‐Younger Dryas exposure ages of 13.4 ± 0.5 ka in Torridon, and 17.5 ± 1.2 ka in Applecross. The Younger Dryas exposure ages have compelling implications for the deglaciation of marginal Loch Lomond Stadial ice fields in Torridon and Applecross. Firstly, they conflict with predictions of restricted ice cover and rapid retreat based on modelling experiments and climate proxies, instead fitting a model of vertically extensive and prolonged ice coverage in Wester Ross. Secondly, they indicate that >2 m of erosion took place in the upper valleys of Torridon and Applecross during the Younger Dryas, implying a dominantly warm‐based glacial regime. Finally, the exposure ages have clarified that corrie (cirque) glaciers did not readvance in Wester Ross, following final deglaciation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献