孟加拉湾晚第四纪浮游有孔虫及其古海洋学意义   总被引：7，自引：1，他引：6  

丁旋  方念乔 《现代地质》1999,13(1):37-42

对北印度洋孟加拉深海扇远源区水深约３８００ｍ的ＭＤ７７１９０岩心进行了有孔虫定量统计,ＣａＣＯ３质量分数分析和敏纳圆幅虫壳体氧、碳同位素分析,结果表明,该区近１３０ｋａ来的浮游有孔虫组合面貌、表层海水古温度、ＣａＣＯ３质量分数变化的总体趋势与各大洋资料可以对比。ＣａＣＯ３质量分数曲线表现为间冰期升高而冰期降低,反映了研究区陆源碎屑物质对ＣａＣＯ３浓度具有明显的稀释效应。溶解度曲线也表现出相同的变化趋势,同样与陆源物质输入量的变化有关。研究区氧同位素３期各种沉积特征与北印度洋区的季风活动有关,表现出明显的高频气候旋回变化特点。  相似文献   

Aptian bio-events—an integrated biostratigraphic analysis of the Almadich Formation, Inner Prebetic Domain, SE Spain     

Roque Aguado  Jos Manuel Castro  Miguel Company  Gins Alfonso De Gea 《Cretaceous Research》1999,20(6):663

The Upper Barremian to Aptian Almadich Formation (Inner Prebetic Domain of the Betic Cordillera) is composed of hemipelagic sediments deposited on a distal carbonate ramp in the southern Iberian Palaeomargin. Within this facies we have found a thick interval of blue to black shales and marls that is interpreted as deposited under oxygen-depleted conditions. We think that this interval, dated as early Aptian, represents the local record of Ocean Anoxic Event 1a. The integrated biostratigraphic analysis of a section in the Almadich Formation, by means of planktonic foraminifera, calcareous nannofossils and ammonites, enables us to recognize most of the biostratigraphic units based on these three fossil groups and to correlate between them. The Sartousiana, Sarasini, Weissi, Deshayesi and Furcata (ammonite) Zones were identified for the Upper Barremian–Lower Aptian interval. By means of calcareous nannofossil biostratigraphy the Micrantholithus hoschulzii, Hayesites irregularis and Rhagodiscus angustus Zones, plus several additional biohorizons, were identified. A quantitative study performed on a set of 27 Lower Aptian samples has enabled the precise identification of the ‘nannoconid crisis’, the lower limit of which clearly precedes the main anoxic event, and its correlation with other bioevents. Planktonic foraminifera occur consistently throughout the Lower to Upper Aptian of the Cau section and are moderately well preserved. This fact allows us to use the most recent taxonomic framework, based on wall texture, to identify the Blowiella blowi, Schackoina cabri, Globigerinelloides ferreolensis, Globigerinelloides algerianus, Hedbergella trocoidea andTicinella bejaouaensis Zones. Coincident with the anoxic episode, the planktonic foraminiferal assemblages are composed of a significant number of forms with elongated chambers and/or tubulospines assigned to the genera Claviblowiella,Lilliputianella , Leupoldina and Schackoina. Most of the planktonic foraminiferal and nannofossil taxa are illustrated.  相似文献   

东北太平洋胡安·德富卡隆起西翼晚第四纪以来的碳酸盐记录     

陈荣华  赵庆英  Alan C Mix  王小波 《海洋地质与第四纪地质》2005,25(1):41-46

通过对东北太平洋胡安·德富卡隆起西翼沉积柱样中的碳酸盐含量和浮游有孔虫氧同位素测试以及浮游有孔虫丰度、溶解指数和粗组分的统计,发现在晚第四纪约65 ka以来碳酸盐含量变化幅度大(0 4%~77 2%),相差非常悬殊,但其变化未呈现出冰期时溶解作用减弱、间冰期时溶解作用强烈这样明显的旋回性。粗组分分析结果显示,地层中有明显的浊流沉积发育。另外,碳酸盐含量和浮游有孔虫丰度分析结果揭露了研究区的 CCD在3 500 m左右。研究认为,在约65 ka来水深浅于3 500 m的区域碳酸盐含量的无规律性变化应与浊流沉积影响有直接的关系,而水深深于3 500 m的区域碳酸盐含量主要受控于深海碳酸盐的溶解作用。  相似文献   

外源溶解性有机碳对抚仙湖甲壳类浮游动物碳源的贡献   总被引：2，自引：1，他引：1  

孙欢  张永东  于谨磊  胡金润  刘正文  苏雅玲 《湖泊科学》2017,29(4):887-895

外源溶解性有机碳(DOC)是湖泊碳库的重要组成部分,关于外源DOC对浮游动物的贡献及途径需要深入研究.本研究在抚仙湖受控实验中添加13C标记的葡萄糖,通过分析样品中浮游植物与浮游动物的种类、数量、磷脂脂肪酸生物标志物及其稳定同位素特征,研究外源DOC对湖泊甲壳类浮游动物碳源的贡献比例及其变化.结果表明:细菌、甲壳类浮游动物(象鼻溞)的δ~(13)C值在加入葡萄糖后分别从-16.28‰和-23.88‰快速增加到5408.25‰和1974.7‰,而藻类磷脂脂肪酸(C18∶2ω6)δ~(13)C值从-27.07‰增加到342.44‰,增长的幅度表明添加的葡萄糖首先被细菌和浮游动物快速利用,而藻类只利用了一小部分.同时细菌、颗粒性有机物(POM)和浮游动物的δ~(13)C值在第1 d急剧增加,细菌的δ~(13)C值远大于浮游动物和POM的δ~(13)C值,之后细菌和POM的δ~(13)C值开始下降,但浮游动物的δ~(13)C值却仍在缓慢增加,进一步表明了DOC进入湖泊后首先被细菌吸收利用,而细菌吸收DOC后通过自身代谢作用形成细胞颗粒,浮游甲壳类动物通过摄食细胞颗粒来获得外源DOC.  相似文献   

鄱阳湖都昌自然保护区浮游甲壳动物群落时空分布特征及其驱动因子     

于新平  陈宇炜  王俊颉  李瀚成  邓枫  徐光锋  夏雨  刘金福 《湖泊科学》2023,35(3):998-1008

江西省都昌候鸟省级自然保护区作为鄱阳湖流域内占地面积最大的自然保护区,承担着保护世界性和国家重点保护濒危越冬候鸟资源等重要责任。探究都昌候鸟自然保护区浮游甲壳动物群落结构及其主要影响因子,可为都昌保护区内鸟类栖息地的生境保护与动态评估提供科学依据。2019—2021年1、4、7和10月对都昌保护区内4个区域的浮游甲壳动物的密度、生物量和水环境因子进行采样调查,运用多样性指数、Pearson相关性和冗余分析(RDA)等对都昌保护区水质情况以及浮游甲壳动物与水环境因子和叶绿素a之间的关系进行解析。结果显示,调查期间共鉴定出浮游甲壳动物31种,其中枝角类(20种)和桡足类(11种)。都昌保护区浮游甲壳动物年均密度213.81 ind./L,年均生物量为1.51mg/L。都昌保护区浮游甲壳动物群落结构时空变化较大,季节上,夏季或秋季浮游甲壳动物的生物量达到峰值,冬季浮游甲壳动物种类最少;空间上南矶一般区(D4)浮游甲壳动物密度和生物量较大,其次是撮箕湖一般区(D3),小矶山核心区(D1)和三山核心区(D2)差异较少。根据多样性指数和均匀度指数分析都昌保护区水质情况,结果表现为撮箕湖一般区(D3...  相似文献   

桑沟湾养殖生态系统微食物环对长牡蛎(Crassostrea gigas)碳需求的贡献     

杜美荣  李凤雪  方建光  高亚平  房景辉  蒋增杰  王同勇 《海洋与湖沼》2019,50(6):1334-1342

采用海域大规模调查和模拟现场流水法测定了桑沟湾海域微食物环主要组分生物(微微型浮游生物、微型鞭毛虫和纤毛虫)在桑沟湾的季节分布和对长牡蛎食物来源的贡献。对桑沟湾海域浮游生物现存量的调查结果显示:微食物环生物丰度和生物量以冬季最低(P0.05)。微食物环组成生物的生物量以微型鞭毛虫最大,占51.69%(无色素体微型鞭毛虫HNF贡献37.31%,有色素体微型鞭毛虫PNF贡献14.38%),其次是异养细菌(39.03%),纤毛虫和微微型真核浮游生物贡献较小,分别为2.31%和0.66%。使用模拟现场流水法,测定了长牡蛎对浮游生物的摄食,其清滤率变化范围为0.26—3.50L/(g·h),随着粒径的增大,长牡蛎对浮游生物的清滤率增加。长牡蛎对不同浮游生物的清滤率由大到小依次为:2μm以上有色素体浮游生物纤毛虫2μm以下有色素体浮游生物无色素体微型鞭毛虫异养细菌,长牡蛎对2μm以上有色素体浮游生物碳截留最大(289.20±62.36μg/(g·h)),其次是无色素体微型鞭毛虫,异养细菌和纤毛虫。传统的对于贝类食物来源的测定忽略了异养细菌、HNF以及纤毛虫,对微食物环框架的研究得出三种生物对长牡蛎的碳贡献为1563.58μg/(g·d)(17.94%),指示原生动物(异养鞭毛虫和纤毛虫)在长牡蛎的食谱组成中的地位不可忽视。异养细菌除了参与微食物环,还能被长牡蛎直接或者间接的摄食,成为长牡蛎的食物来源之一。本文结果为长牡蛎的养殖容量评估和微食物环生物对养殖生态系统的贡献分析提供了重要的数据支撑。  相似文献   

Mid Pleistocene climate instability in the subtropical northwestern Atlantic     

K. Billups  C. Lindley  J. Fisler  P. Martin 《Global and Planetary Change》2006,54(3-4):251-262

We present Globigerinoides ruber, G. sacculifer and Neogloboquadrina dutertrei oxygen isotope records from northwestern subtropical Atlantic Site 1058 spanning the mid Pleistocene ( 600 to 400 ka). The high temporal resolution of these records ( 800 yr) allows us to compare millennial-scale climate signals during one of the most extreme glacial periods of the Pleistocene (Marine Isotope Stage (MIS) 12) to an earlier, less extreme glacial (MIS 14), as well as to two full interglacial intervals (MIS 13 and MIS 15). We observe excellent agreement in the timing and amplitude of variations between the surface-most dwelling species G. ruber and Northern Hemisphere insolation during the two interglacial periods. There is some expression of Northern Hemisphere insolation during glacial MIS 14; however, during the more extreme glacial MIS 12 Northern Hemisphere insolation patterns are not apparent in any of the planktonic foraminiferal δ¹⁸O records. Insolation remains relatively high, but δ¹⁸O values increase toward the characteristic δ¹⁸O maximum of MIS 12 in all three of the records. On the millennial-scale, all three species display their highest amplitude δ¹⁸O variations (with a period between 4–6 kyr) during glacial MIS 12. Suborbital-scale variability is also statistically significant during glacial MIS 14, but the amplitude is smaller. These results support hypotheses linking millennial-scale climate fluctuations to the extent of continental glaciation. We propose that the relatively high degree of sea surface instability during one of the most extreme glacial periods of the Pleistocene arises from the competing effects of strong atmospheric winds related to the presence of a large ice sheet to the north and persistently high incident solar radiation during this interval of time.  相似文献   

Pleistocene biogeochemical record in the south‐west Pacific Ocean (images site MD97‐2114, Chatham Rise)     

M. Cobianchi  V. Luciani  C. Lupi  N. Mancin  F. Lirer  N. Pelosi  I. Trattenero  M. Bordiga  I. R. Hall  M. Sprovieri 《第四纪科学杂志》2012,27(5):519-530

Through a multidisciplinary approach based on novel micropaleontological and geochemical analyses, the main paleoceanographic and paleoclimate changes that have influenced the surface‐ and deep‐water circulation in the SW Pacific Ocean (Chatham Rise, eastern New Zealand) during the last million years are reconstructed. This region represents a key area for investigating the climate evolution during the Pleistocene because here the largely wind‐driven Antarctic Circumpolar Current interacts with the west Pacific Ocean circulation via the Deep Western Boundary Current, the major source of deep water for the whole Pacific Ocean. To understand coupling or decoupling events between sea surface and bottom waters, a continuous marine sedimentary succession since 1.1 Ma, recovered by the IMAGES (International Marine Past Global Change Study) cruise in the SW Pacific Ocean (Core MD97‐2114), has been investigated based on calcareous planktonic and benthic microfossil content and C and O isotope record performed on planktonic and benthic foraminiferal tests. Results show the occurrence of long‐ and short‐term patterns of climate and ocean circulation in the last million years as the result of the interplay of ice‐sheet dynamics, surface tropical versus polar water inflow, and trophic status of the surface water. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

南海北部晚更新世以来的古海洋环境演化特征——来自N-31柱样的沉积记录     

李小艳  翦知湣  石学法  程振波  陈志华  李朝新  吴永华  石丰登 《沉积学报》2011,29(3):572-579

对南海北部N-31柱状样沉积物进行了浮游有孔虫定量分析鉴定、氧碳同位素、碳酸盐含量和粒度测试以及AMS14C测年,并采用古生态转换函数计算了表层海水古温度和温跃层深度,揭示了该海区约55 ka以来的古海洋环境特征.转换函数计算的表层海水古温度结果表明,夏季温度的变化范围为27.0～29.6℃,变化幅度为2.6℃,冬季温...  相似文献   

鄂霍次克海南部OS03-1岩心MIS6期以来的沉积记录及其古环境意义   总被引：2，自引：1，他引：1  

司贺园  侯雪景  丁旋 《现代地质》2011,25(3):482-488

通过对取自鄂霍次克海南部的柱状岩心OS03-1的古海洋学研究,包括浮游有孔虫壳体AMS14C测年、底栖有孔虫壳体δ18O分析、蛋白石含量测定、有机碳含量测定、浮游有孔虫组合、冰筏碎屑含量变化、沉积物粒度分析等内容,建立鄂霍次克海OS03-1岩心年代地层学框架,分析该海区古表层海水温度、古生产力变化,并研究其古环境意义。结果表明,Neogloboquadrina pachyderma(sin.)百分含量变化曲线与Globigerina bulloides百分含量变化曲线呈很好的负相关性,与氧同位素曲线对比显示,两者均可作为该海区古温度替代性指标;浮游有孔虫绝对丰度、蛋白石含量、有机碳含量变化显示,研究区古生产力水平整体表现为间冰期较高、冰期较低;冰筏碎屑和沉积物粒度特征指示,鄂霍次克海南部间冰期陆源粗颗粒百分含量较冰期高。  相似文献