通过对白令海盆中部BR02岩芯高分辨率的颜色、粒度和元素地球化学地层的研究发现:(1)该岩芯较为完整地记录了末次盛冰期结束以来(约16.3 ka BP)的多期冰筏碎屑事件,包括H1、OD、YD和北方2期,其中以H1和YD最为显著,反映了末次冰消期以来该地区海冰/冰山以及区域性冰川的消长变化;(2)BR02岩芯上部17—25 cm段出现富Mn、富Ba的氧化型沉积,说明在全新世高海面时期,白令海与北太平洋、北冰洋之间的水体交换达到极点,白令海环流加强,海盆底层水含氧状况明显改善,并引发海洋生产力增加;(3)CaO、Na2O、Sr、Zr及Na2O/K2O比值的分布说明,海盆冰筏碎屑主要来自富碳酸盐的育空河流域,其次为阿拉斯加半岛和阿留申群岛等火山岩区;岩芯上部Na2O/K2O比值的递增暗示10 ka BP以来与火山物质输运有关的北太平洋入流(阿拉斯加流)可能增加。

From a high-resolution study of sediment grain size,color reflectance and elemental stratigraphy of core BR02, which was dredged from the central part of the Bering Basin,we came to the following conclusions.(1 )Core BR02 provides perfect records of the ice-rafted detritus (IRD)events that have happened since 16.3 ka BP at the end of the Last Glacial Maximum,including the H1 ,OD,YD and Boreal 2 events,of which H1 and YD are the most sig-nificant.These IRD events all happened during cold episodes or stadials,and indicate changes in sea ice/icebergs in the sea and local glaciers in the surrounding lands.(2)The interval of Mn-and Ba-rich sediments at 17-25 cm in the upper part of BR02 indicates that water exchange between the North Pacific Ocean,the Bering Sea,and the Arctic Ocean increased to its highest level during the Holocene high-sea-level period,which induced changes in the circulation and seabed redox and an increase in marine productivity in the Bering Basin.(3)The concentrations

通过对比白令海BR07孔与B5-4孔硅藻百分含量、颜色反射率等参数结果,综合建立了BR07孔年龄框架。根据该重建年龄结果,BR07孔年龄约为11.3~1.9ka,平均沉积速率约为28.5cm/ka,略低于B5-4孔。基于圆柱拟脆杆藻与塞米新细齿藻比值Fragilariopsis cylindrus含量/(Fragilariopsis cylindrus含量+Neodenticula seminae含量)重建的近万年来白令海海冰变化历史,记录到该区域末次冰消期以来包括新仙女木事件在内的3次冷事件以及1次暖事件,其中新仙女木事件约发生于距今11.3~10.7ka,与格陵兰冰心记录对应值距今12.9~11.6ka基本相近,这进一步佐证了该重建年龄比原始的全样有机碳AMS 14C测年结果更可信。

T he age model of Core BR07 is reconstructed based on the comparisons of diatom distributions and color parameters of the sediments between Cores B 5-4 and BR07 ,both collected from the northern continental slope of the Bering Sea .According to this age model ,the deposition ages of Core BR07 range from 1.9 to 11.3 kaBP ,with an average sedimentation rate of 28.5 cm/ka which is slightly lower than that of Core B5-4 .A sea-ice proxy ,de-fined as the ratio of Fragilariopsis cylindrus content to (F .cylindrus content+ Neodenticula seminae content) ,is proposed to reconstruct the historic climate record of sea-ice changes over the last 10 ka .Three cold events (inclu-ding the Younger Dryas cold event ) as well as one warm event since the last deglacial period have been detected in the core .T he reconstructed time span of the Younger Dryas cold event in Core BR 07 is 11.3~10.7 ka BP ,close to its correspondent of 12.9~11.6 ka BP from Greenland ice cores ,further confirming that it is more

利用中国历次北极科学考察航次在白令海北部陆坡及海盆等深水区所采集的沉积物样品,对其开展沉积学等研究,系统归纳该海域常见的异常沉积类型及特征,并初步探讨其可能成因。BR02孔出现至少3段浊积层,浊积层主要分布于末次冰消期至中全新世。B5-4孔存在至少2段火山碎屑沉积层,其沉积年代分别约为1.3 ka BP和13.2 ka BP。B5-7站表层沉积物中的硅藻组合以新近系硅藻化石Kisseleviella carina Sheshukova-Poretzkaya和Kisseleviella ezoensis Akib为主,且与附近海域其他表层沉积物的硅藻组合面貌差异明显,可能是沉积物再沉积结果,其初始沉积年代大约为早中新世。白令海北部陆缘/陆坡区附近遍布的海底大峡谷对该区沉积物沉积过程具有重要影响,可能是导致该区浊流沉积与再沉积物的主要原因。此外,白令海位于欧亚板块、太平洋板块及北美板块交汇区边缘,其独特的地理位置决定该区地震与火山等构造活动相对活跃,进而进一步促使该区海底异常沉积现象频发。

Sediment samples from previous Chinese Arctic Research Expeditions in the northern continental slope and thedeep basin of the Bering Sea were used for sedimentological studies.Abnormal sedimentary types and their charac-teristics are summarized,and their possible causes are preliminarily discussed.At least three turbidite layers appearin core BR02,which are distributed mainly from the last deglacial to the Mid-Holocene.More than two volcaniclas-tic sedimentary layers were found in Core B5-4,which formed at ca.1.3 ka BP and 13.2 ka BP.The diatom as-semblage of the surface sediment of Core B5-7 is dominated by the Neogene fossil diatoms Kisseleviella carina She-shukova-Poretzkaya and Kisseleviella ezoensis Akib,which is distinctively different from the assemblages in other ad-jacent surface sediments.We presume that this could be the result of reworking,and its initial depositional agecould be about early Miocene.The numerous submarine canyons incising the continental margin of the Berin

对中国首次(1999年)和第二次(2003年)北极科学考察在楚科奇海及邻近的北冰洋深水区采取的47站表层沉积物进行了碎屑重矿物鉴定分析。结果表明北冰洋西部表层沉积物中重矿物以抗风化能力较弱的绿帘石、紫苏辉石和普通角闪石为优势矿物,钛铁矿、石榴子石、磷灰石和赤铁矿为特征矿物。矿物组合分区表明研究区物质来源和水动力变化较为复杂:白令海峡以南沉积物中重矿物含量高,水动力强;白令海峡以北的洋流变化与所经区域沉积物重矿物种类和含量变化相一致,即楚科奇海中部沉积物富集紫苏辉石、钛铁矿和石榴子石,物质来源可能与楚科奇山原相关,而在阿拉斯加沿岸沉积物中富集绿帘石和紫苏辉石,与阿拉斯加沿岸流携带物质相关;楚科奇海北部深水区碎屑矿物沉积速率低且矿物多有蚀变。

The composition,assemblage and distribution characteristics of heavy minerals in 47 surface sediment samples from the Chukchi Sea and the adjacent Arctic Ocean were identified.The sediments were collected during the first and second Chinese National Arctic Research Expeditions,in 1999 and 2003.The results show that the heavy min-erals in the surface sediments of the western Arctic Ocean are mainly epidote,hypersthene and hornblende with a low resistance to weathering,and ilmenite,garnet,apatite and hematite are characteristic minerals.The mineral assemblages and distribution indicate that the material sources and the hydrodynamic conditions in the study area are complicated.The content of heavy minerals is higher in the southern part of the Bering Strait,indicating strong hydrodynamic action.The sediments in the central Chukchi Sea are enriched in hypersthene,ilmenite and garnet, the source of which may have been the Chukchi plateau,whereas in Alaska coastal sediments enriched in epido

通过对2008年夏季楚科奇海水氧同位素组成的分析,运用S、δ^18 O的质量平衡关系计算出河水组分和海冰融化水组分的份额,揭示出楚科奇海河水和海冰融化水组分的空间变化规律,并探讨其影响因素。楚科奇海河水组分的份额介于1.9%～18.4%之间,呈现随深度增加而降低的趋势;河水组分积分高度的变化范围为1.3～16.6m,平均为（4.8±4.0）m。河水组分份额与积分高度均呈现东高西低、北强南弱的特征,与太平洋入流东侧为富含河水组分的阿拉斯加沿岸流、西侧为低河水组分的白令海陆架水,以及北部海域受波弗特流涡埃克曼辐聚作用的影响有关。海冰融化水份额呈现随深度增加而降低的趋势,20～30m以深受到冬季海冰形成时所释放盐卤水的明显影响。海冰融化水积分高度的变化范围为-3.2～1.7m,平均值为（-0.3±1.2）m,其空间分布呈现东低西高、南强北弱的特征,与太平洋入流输入通量的时间变化以及输入路径的西偏有关。

On the basis of the measured oxygen isotopic composition of seawater,the S andδ18 O mass balance was employed to determine the fraction of river water and sea-ice melted water in Chukchi Sea in summer 2008.The spatial patterns of river water and sea-ice melted water were revealed and the affecting factors were disccussed.The fractions of river water decreased with the increasing depth,with a range from 1.9% to 18.4%.The integrated heights of river water (I fR )were 1.3~16.6 m,with an average of (4.8±4.0)m.I fR showed a spatial characteristic with high values in the east and north and low values in the west and south.This spatial variation of river water was ascribed to the difference amount of river water carried by the Pacific inflows (e.g.,high river water compo-nents in the Alaska Current Water and low river water components in the Bering Shelf water),the pathway of the Pacific inflows and the Ekman pumping of Beaufort Gyre.The fractions of sea-ice melted water decreased