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1.
扫描电镜分析各类微体化石样品最佳镀膜的探讨 总被引：1，自引：0，他引：1
根据多年的工作经验和试验对比,总结出了非导电微体化石－放射虫,硅藻,竹节石,有孔虫,介形虫,轮藻,牙形石,海绵骨针等的最佳镀膜方法和最佳镀膜厚度。 相似文献
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放射虫岩是指主要由放射虫壳体堆积的一种“化学-生物化学岩”。放射虫吸收海水中的硅质组成以含水的SiO2为成分的壳体。在放射虫岩中,常常还有海绵骨针和硅藻等生物遗迹。卡洛瑞（Carozzi,A.V.1960）把已发现的放射虫岩分为四种:砂质放射虫岩、钙质放射虫岩、铁质放射虫岩（红放射虫岩）和炭质放射虫岩（黑放射虫岩）。实际上放射虫岩主要是硅质为主。广东曲江-仁化地区早二叠世“当冲层”的放射虫岩是一种硅质放射虫岩,本文试就其成因、古地理环境的变迁及与成矿和古构造活动的联系作一初步探讨。 相似文献
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为了多角度理解海洋纹层沉积物的形成过程,利用在西菲律宾海采集到的含纹层硅藻席的XT47孔岩心样品,进行多囊虫类放射虫的组合变化与环境意义分析.研究表明XT47孔岩心上段260 cm厚硅藻席沉积中含有丰富的放射虫、丰度高于2×104个/克;中段260~460 cm出现5次放射虫丰度高峰与红粘土的交替旋回沉积;下段460~630 cm红粘土沉积层中放射虫稀少.依据放射虫地层种的初现生物事件,470 cm以深的年龄大于0.34 Ma,表明西菲律宾海硅藻质沉积形成于中更新世以来.此外,受暖水影响控制的Tetrapyle group和Didymocyrtis tetrathalamus tetrathalamus相对丰度在末次冰盛期（LGM）呈现显著的低值期,推测在LGM期西菲律宾海北赤道暖流的影响强度是变弱的.值得注意的是,多囊虫类放射虫的丰度与生物硅含量的变化趋势出现明显的不同步现象,推测4次生物硅含量高峰是由大型硅藻（盘筛藻）的急剧增加导致的,即西菲律宾海LGM期盘筛藻的勃发呈现明显的阶段性强弱变化;进一步发现盘筛藻的4次勃发强盛期对应着胶体虫相对丰度变化的低谷期和中深层冷水种相对丰度变化的高峰期,前者指示上层水体成层化减弱、后者指示中深层水体中营养物增多.据此,认为西菲律宾海LGM期盘筛藻勃发的4次强盛期是由于上层水体成层化减弱、下层水体中丰富的营养物上涌引起.研究结果可为菲律宾海盘筛藻勃发在LGM长时间持续并最终在海底形成厚达近3 m的硅藻席沉积提供了一种可能的解释. 相似文献
4.
热带东太平洋8001柱状样晚第四纪以来放射虫标志种Buccinospharea invaginata和Collosphaera tuberosa的研究发现, 它们的初现面(FAD) 出现于柱深22cm和45cm处, 年龄分别为0.21Ma和0.42Ma.它们的初现面年龄与SPECMAP氧同位素记录结合为该柱建立了地层框架.该柱放射虫丰度、生源蛋白石和有机碳含量、粒度的分析显示, 大约在氧同位素11、9~8.4、5~3和1期, 高的放射虫总丰度、第四纪常见种丰度和始新世-渐新世种丰度大致对应于高的中值粒径和平均粒径, 以及大约氧同位素5期以来增加的有机碳含量, 表明此期间贸易风增强, 搬运的陆源颗粒增大, 北赤道洋流加强, 导致上升流增强, 表层水生产力提高, 同时, 南极底层流的活动也加强.大约在氧同位素10、8.3~6和2期, 低的放射虫总丰度、第四纪常见种丰度和始新世-渐新世种丰度大致对应于减小的中值粒径和平均粒径, 反映此期间贸易风减弱, 搬运的陆源颗粒减小, 北赤道洋流减弱, 导致上升流消失, 表层水生产力降低, 同时, 南极底层流的活动也减弱. 相似文献
5.
武昌地区孤峰组硅质岩主要包括放射虫岩、海绵骨针岩和微晶硅质岩。将这些岩石样品浸入氢氟酸（５—１０％）中１２—２４ｈ，可见清楚的沉积构造。孤峰组上部具丰富的放射虫化石，发育块状层理、条带状层理和三分层理，形成于深水盆地环境；下部具丰富的海绵骨针，发育滑塌构造、粒序层理、水平层理、波状层理，形成于较深水斜坡环境。 相似文献
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通过对鄂西宜昌地区寒武系岩家河组—水井沱组页岩进行高分辨率样品采集,利用总有机碳(TOC)含量、主量元素分析、氦孔隙度等定量分析和透反射光显微镜、阴极发光显微镜等定性分析相结合的方法,研究了水井沱组黑色岩系生物成因硅的纵向变化特征及其与页岩气富集的关系。结果表明：寒武系底部岩家河组和水井沱组上部贫有机质层段过剩硅含量低,未见明显生物碎屑痕迹,几乎不含或含少量自生成因石英,而水井沱组富有机质层段存在较多生物成因硅,具有明显的分段性(一段、二段)且硅质来源明显不同。富有机质层段底部(一段)过剩硅含量高,为4.44%～24.97%,平均值为16.76%,受钙质夹层的影响波动较大,生物成因硅占比高,受陆源碎屑影响小。生物碎屑类型主要为硅质海绵骨针,还有少量絮状硅质聚集体,骨针腔体和硅质聚集体粒间孔中可见有机质。而富有机质层段中上部(二段)过剩硅含量相对一段明显降低,为7.13%～20.47%,平均值为13.66%,受陆源碎屑影响更大。生物碎屑类型主要为放射虫、纺锤状硅质聚集体和海绵骨针,可见有机质与这些生物成因硅和陆源碎屑共生在一起。在整个富有机质层段,TOC含量与总硅含量无明显关系但与过剩硅... 相似文献
8.
本文对“第33次南极科考—海洋六号航次”在乔治王岛南侧、象岛西侧海域内通过箱式取样获得的表层沉积物样品进行了硅藻组成和分布特征的研究。主要统计了硅藻丰度、简单分异度、属种组成等, 并结合沉积物粒度数据进行分析, 结果表明乔治王岛南侧站位丰度和分异度高于象岛西侧站位, 最高丰度达到1.96×106壳/g。丰度的差异分布可能主要与洋流有关, 别林斯高晋海表层洋流带入充足营养盐导致乔治王岛南侧站位硅藻繁盛, 而威德尔海涡流底层水影响下的象岛西侧站位则难以沉降保存包括硅藻壳体在内的细小沉积颗粒。各站位硅藻组成的差异主要体现在海冰相关种分布不均和半咸水种类繁盛情况等, 前者可能与漂浮海冰控制的时间长短有关, 而后者与淡水输入等综合环境因素有关。 相似文献
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新第三纪沉积物连续分布在位于日本海东南部Sado岛Oosado山脉的两侧,以中中新统到上新统,Nakayama组由具纹理的、生物扰动的和块状的硅藻泥岩组成。纹理由白色层和黑色层组成并间夹0.02～1mm厚的灰色层。白色纹层主要由硅藻壳组成,而黑色纹层则由如硅藻、海绵骨针、硅鞭藻、放射虫、碎屑颗粒和有机质的混合物组成。生物扰动泥岩中具有Thalassionoides,Planolites,Zoophcos,Chondrites遗迹化石(生物钻孔)。 相似文献
10.
南海表层沉积物中放射虫的组合特征与海洋环境 总被引：3，自引：2，他引：1
南海拥有较齐全的边缘海地理地貌与生态环境, 沉积物中保存的放射虫种类繁多, 个体丰富.本文采用数理统计与聚类分析方法, 对表层沉积物中放射虫的组合特征进行了较为详细的定量分析, 以期获得可靠的放射虫组合与分布的特征.聚类分析结果显示, 放射虫组合在南海表层沉积物中的分布大致可区分为5种类型: 陆架浅水区型、陆坡珊瑚礁区型、中央海盆区型、南部富营养区型和夏季上升流区型, 它们分别对应于特有的海洋环境, 并由含有某些优势种类的放射虫群落所组成.进一步分析还表明, 南海的北部、中部和南部分别表现为3个不同生态环境的海区: 北部海区受陆源影响较为明显; 中部海区被中央水团、海底火山活动和夏季上升流活动所控制; 南部海区总体上属于典型的珊瑚礁海洋环境, 生态与沉积环境明显优越于北部海区.南海表层沉积物中放射虫的组合分布特征较好地响应和反映了所在海区的生态环境与沉积条件, 是探讨古海洋环境的重要依据. 相似文献
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白令海楚科奇海的海冰范围变化特征 总被引：3，自引：0，他引：3
白令海和楚科奇海位于北极太平洋一侧的海冰外缘线附近,具有较强烈的气冰海相互作用.采用滑动t检验和小波分析方法对白令海和楚科奇海1953—2004年海冰范围的年际变化、年代际变化和总体趋势变化进行分析.结果表明:20世纪70年代后期,海冰范围在白令海存在显著的均值突变现象,而楚科奇海在对应阶段则表现为更明显的变频现象;在突变点前后两个时段里,阿留申低压中心低压加强、核心位置偏移以及对应风场分布的变化是导致白令海海冰范围明显缩小的主要动力原因.楚科奇海海冰范围的年际变化中存在由低频向高频变化的现象,该现象除了在局地气温变化中存在之外,在北冰洋区域风涡度、波弗特海纬向风、东西伯利亚海经向风等动力因素中也有所体现.因此,除热力因素外,动力因素引起的海冰的平流与该变频现象也存在一定的联系. 相似文献
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白令海北部陆坡100ka来的古海洋学记录及海冰的扩张历史 总被引：4，自引：0，他引：4
白令海北部陆坡B2-9柱状样中生源组分的研究显示, 自MIS5.3期以来表层生产力指标的粗组分和蛋白石含量呈阶梯状增加, 反映表层生产力阶段式的增长.全新世表层生产力达到最高, 并且MIS3.2~2期高, 比MIS5.3~3.3期最低.高有机碳含量对应于高C/N比值, 显示有机碳混合来源, 不能作为表层生产力的指标.MIS5.1, 3.3~3.2期和全新世高的有机碳含量和C/N比值反映间冰期陆源有机物质输入量的增加.MIS5.3期至中全新世, 不断增加的陆源砂级和粉砂级颗粒组分说明随着气候的逐渐变冷, 陆架海冰在不断扩张.伐冰碎屑和碳屑颗粒冰期、间冰段和末次冰消期升高, 而间冰期降低, 反映冰期白令海陆架海冰扩张和间冰期海冰消融的过程.冰期海冰扩张与北美大陆气候的相互关联, 揭示了晚第四纪冰期旋回中白令海海冰扩张及其对全球气候变化的响应. 相似文献
13.
Surface sediments from the Outer Continental Shelf of Alaska were analyzed for hydrocarbons as part of an environmental survey sponsored by NOAA/BLM. Sediments were collected from the proposed oil lease areas of Beaufort Sea, southeastern Bering Sea, Norton Sound, Navarin Basin, Gulf of Alaska, Kodiak Shelf and lower Cook Inlet. Data on normal and branched alkanes and di- and triterpenoids from capillary gas chromatography (GC) and gas chromatography-mass spectrometry (GC/ MS) indicate that the area displays little evidence of petroleum hydrocarbons (i.e., seeps) except at a few isolated stations. Beaufort Sea sediments have the highest hydrocarbon budget, whereas Kodiak Shelf sediments have the lowest. The molecular markers of the hydrocarbons are of a mixed marine autochthonous and terrestrial allochthonous origin. Norton Sound and Cook Inlet sediments contain the highest levels of terrigenous lipids and Kodiak Shelf the lowest. The abundance of alkenes implies that relatively low oxidizing conditions exist in some of the depositional areas studied, suggesting that extraneous petroleum hydrocarbons introduced into these sediments would be expected to have a relatively long residence time. The distribution of polynuclear aromatic hydrocarbons (PAH) is complex and shows a pyrolytic origin. The data on perylene strongly favor the hypothesis that it is “performed” from terrigenous precursors and transported into the marine environment with no apparent in situ generation. Polynuclear aromatic hydrocarbons of diagenetic origin are probably dominant in Gulf of Alaska and Kodiak Shelf sediments.Two stations, north of Kalgin Island, in lower Cook Inlet and one in southeastern Bering Sea show typical weathered petroleum distribution of n-alkanes and triterpenoids. Probable pathways of transport and fate of petroleum hydrocarbons in case of an oil spill are also briefly discussed. 相似文献
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通过对中国第3次和第4次北极考察在白令海和西北冰洋采集的65个表层样沉积物中生物标记物四醚膜类脂物(GDGTs)的研究,发现西北冰洋表层沉积物中类异戊二烯和支链GDGTs的浓度分布大致以楚科奇海和波弗特海的陆坡为界线,呈现南高北低的特征,这一特征主要与水体生产力和陆源有机质的输入量有关.基于GDGTs的陆源输入指数BIT显示,从楚科奇海北部到高纬度区的阿尔法脊,陆源有机质的相对比例明显增加,与有机碳稳定同位素等结果一致,表明BIT可以用来指示北极陆源有机质输入量的变化.应用前人TEXL86-SST方程估算的研究区表面海水温度SST与现代年均SST和夏季平均SST的相关性较差,原因可能与陆源输入的类异戊二烯GDGTs干扰以及低的古菌生产力有关.从季节性海冰覆盖区到永久性海冰覆盖区,基于支链GDGTs的环化指数CBT明显升高,可能反映了CBT对海冰覆盖状况的响应,但其响应机制还不清楚.基于支链GDGTs的环化指数CBT和甲基化指数MBT估算的北极陆地年均大气温度和土壤pH差异较大,可能是由表层沉积物的来源复杂以及混合作用造成的. 相似文献
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NS93 5钻孔沉积物高分辨率过渡金属元素变化及其古海洋记录 总被引：6，自引：0，他引：6
利用电感耦合等离子体质谱（ICP－MS）法分析了取自南沙南部陆坡的NS93－5钻孔沉积物的部分过渡金属元素含量的变化。结果表明，代表碎屑物质的量的Ti含量在不同气候时期变化明显，其中在氧同位素第4期碎屑比例最大，第2期和第3期末期，碎屑所占比例比较高，代表较大的碎屑输入通量。但与沉积速率相比较发现，NS93－5的沉积速率并不仅仅决定于碎屑的输入，自生沉积物的累积作用也极为明显。Mn、Mo、Cr、V、U、Cd、Co、Ni、Cu和Zn等元素含量变化表明，NS93－5钻孔沉积物中还原状态极低。反映出自过去15ka以来该区陆坡深度底层海水均富含氧气，并没有出现无氧状态，意味着南沙海域底层海水更新一直都比较快。 相似文献
16.
Two piston cores, one located far from the continents (The North Pacific Ocean: ES core), and another located comparatively closer to the continents (The Bering Sea: BOW-8a core) were investigated to reconstruct environmental changes on source land areas. The results show significant contribution of terrestrial organic matter to sediments in both cores. The δ13C values of n-C27, n-C29, and n-C31 alkanes in sediments from the North Pacific ES core show significant glacial to interglacial variation whereas those from the Bering Sea core do not. Variations of δ13C values of land plant n-alkanes are related to the environmental or vegetational changes in the source land areas. Environmental changes, especially, aridity, rainfall, and pCO2 during glacial/interglacial transitional periods can affect vegetation, and therefore C3 / C4 plant ratios, resulting in δ13C changes in the preserved land plant biomarkers. Maximum values of δ13C as well as maximum average chain length values of long chain n-alkanes in the ES core occur mostly at the interglacial to glacial transition zones reflecting a time lag related to incorporation of living organic matter into soil and transportation into ocean basins via wind and/or ability of C4 plants to adapt for a longer period before being replaced by C3 plants when subjected to gradual climatic changes. Irregular variations with no clear glacial to interglacial trends in the BOW-8a core may result from complex mixture of aerosols from westerly winds and riverine organic matter from the Bering Sea catchments. In addition, terrestrial organic matter entering the Bering Sea could originate from multiple pathways including eolian, riverine, and ice rafted debris, and possibly be disturbed by turbidity and other local currents which can induce re-suspension and re-sedimentation causing an obliterated time relation in the Bering Sea biomarker records. 相似文献
17.
Sunghan Kim Kozo Takahashi Boo-Keun Khim Yoshihiro Kanematsu Hirofumi Asahi Ana Christina Ravelo 《Quaternary Research》2014
Biogenic opal content and mass accumulation rate (MAR) at IODP Expedition 323 Site U1343 were found to fluctuate consistently, generally being high under warm conditions and low under cold conditions during the last 2.4 Ma. Continuous wavelet transform analysis of the normalized biogenic opal content indicates that export production in the Bering Sea varied predominantly at 41-ka periodicity before 1.25 Ma, and shifted to 100-ka periodicity at the onset of the Mid-Pleistocene Transition (MPT; 1.25–0.7 Ma). The 100-ka cycles dominated until the Holocene. Export production in the Bering Sea decreased markedly in the Bering Sea two times during the MPT: the first occurred at the beginning of the MPT (1.25 Ma) and the second in the middle of the MPT (0.9 Ma). These decreases coincided with both increases in the relative abundance of sea-ice diatoms and decreases in the warm-water diatom species Neodenticula seminae, indicating that reductions in export production in the Bering Sea during the MPT were associated with climate cooling. Decreases in export production in the Bering Sea during the MPT were most likely associated with the increased influence of polar/Arctic domains on the high-latitude North Pacific. 相似文献
18.
David T Heggie 《Geochimica et cosmochimica acta》1982,46(7):1301-1306
Copper concentrations have been measured in surface <75 m waters of the central Bering Sea. Concentrations of 2–4 nmole kg?1 were measured in the Zhemchung Canyon region where water depths are greater than 1000 m. Concentrations are higher 2–25 nmole kg?1 on the shallow <100 m continental shelf, inshore of a hydrographic front at the 100 m isobath. Copper-depth profiles on the continental shelf water mass are dominated by Cu concentrations increasing toward the sediments. These trends may be maintained by a flux of Cu from surficial sediments. A frontal system over the 100 m isobath acts to control the flux of Cu, a significant part of which apparently emanates from the sediments, between the continental shelf and the central Bering Sea basin. The benthic shelf Cu flux was constrained to be less than 3 nmole cm?2 yr?1. 相似文献
19.
Airborne microorganisms play an essential role in the microbial propagation and maintenance of the ecosystem diversity, and also significantly affect the climate by acting as effective Ice Nucleus (IN) and Cloud Condensation Nuclei (CCN). The ocean is a vital source and destination for airborne microbes. Nevertheless, little information has been obtained on the distribution of abundance and diversity of airborne microorganisms over the ocean. This paper systematically reviewed the abundance, size distribution, and community structure of airborne microorganisms over the ocean, as well as various environmental and meteorological factors that control the distribution of microbes in marine aerosols. The commonly used methods for detecting airborne microorganisms and their development prospects were also discussed. We pointed out that sampling and detection of extremely low concentration microorganisms in marine aerosols are key problems to be solved in this field, and future research directions include the increase of the cruising observation in open oceans and combination of advanced molecular techniques and other traditional methods. This paper provides extensive and crucial information for subsequently in-depth research on airborne microorganisms over the ocean, revealing their sources, activities, climate and ecological effects. 相似文献