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1.
渤海湾西部现代有孔虫群垂直分带的特征及其对全新世海面、地质环境变化的指示 总被引：3，自引：2，他引：1
对渤海湾西部潮间带和浅海区106个表层底质样品的活体与死有孔虫进行分析,筛选出8个优势种。利用死体有孔虫研究了优势种随水深(高程)变化的垂直分布特征,讨论了不同属种、不同有孔虫垂直组合带与地质环境、海面的定量关系。结果表明,有孔虫属种和组合的指示范围决定其作为地质环境及海面变化指标的灵敏性和精度。确立了研究区有孔虫海相性评价指数及与水深(高程)的相关性。根据对研究结果的实例应用的分析,恢复了研究区一个局部地点的相对海面变化曲线,为全新世地质环境和海面变化研究提供了一个新的尝试案例。 相似文献
2.
Luo Wang Patrick Rioual Virginia N. Panizzo Houyuan Lu Zhaoyan Gu Guoqiang Chu Deguang Yang Jingtai Han Jiaqi Liu Anson W. Mackay 《Quaternary Research》2012,78(1):24-34
Past environmental changes based on diatom relative abundances have been inferred from the maar Lake Erlongwan in northeast China. The limnology of Lake Erlongwan is affected by the strongly seasonal regional climate. The composition of diatom assemblages, in turn, responds to changes in the seasonal duration of ice cover in winter, water-column turnover in spring and autumn, and thermal stratification in summer. Statistical analysis of the sedimentary diatom assemblages reveals three significant stratigraphic zones over the past 1000 yr. The highest abundance of the planktonic species Discostella species occurs between AD 1050 and 1400 and suggests an annual ice-free period of long duration and well-developed summer stratification of the water column. This planktonic diatom peak between ca. AD 1150 and 1200 suggests that this period was the warmest over the past 1000 yr. The interval between AD 1400 and 1800 is marked by a decline in planktonic diatoms and suggests shorter duration of the ice-free season, weaker water stratification and possibly generally cold conditions. After AD 1800 relative abundances of planktonic diatoms, including Puncticulata praetermissa and Asterionella formosa, increase again, which indicates lengthening of the duration of the annual ice-free period and a stronger overturn of the water column. All these data imply that the pattern of the seasons is different between the MWP and the 20th century. 相似文献
3.
南海北部陆坡ODP 1144站位第四纪硅藻及其古环境演变 总被引：9，自引：0，他引：9
中国南海北部陆坡ODP 1144站位硅藻植物群的研究，建立了西太平洋边缘海一个新的中更新世晚期以来的硅藻生物地层图式，根据硅藻化石中具有指示意义的硅藻种的分布和生态变化（暖水种和冷水种），划分了8个硅藻组合带，其硅藻组合带分别在不同的高低海面环境下形成的，根据ODP1144站位氧同位素（OIS）测定结果，8个硅藻组合带与OIS 1－8期相对应。1、3、5、7硅藻组合带相当于OIS1、3、5、7期，间冰期是以热带和亚热带硅藻占优势，其中冷期出现大量的沿岸硅藻为特征，反映高海平面温暖的气候条件；2、4、6、8硅藻组合带相当于OIS2、4、6、8期，冰期是以亚热带，热带和出现较多冷水硅藻为特征，反映低海平面较冷气候条件，硅藻丰度值的变化与冰期和间冰期有关，可以证实间冰期时期高的海平面和较低的生物生产力以及冰期时低的海平面和高的生物生产力，而生物生产力的变化又与沉积时期沿岸流或上升流的强弱及水团活动有密切关系，进而揭示该区古海洋环境的演化与季风强弱之间的内在关系。 相似文献
4.
发现渤海湾中北部表层沉积硅藻21属37种,确定了Cyclotella striata/stylorum,Paralia sulcata和Coscinodiscusperforatus等9个优势种的地理分布;进而根据聚类分析,将研究区表层沉积硅藻划分为6个组合区。讨论了控制它们分布的环境因素,发现盐度与深度是重要控制因素,沉积物底质类型亦对硅藻的分布有一定的影响。 相似文献
5.
C. Samtleben P. Schäfer H. Andruleit A. Baumann K. -H. Baumann A. Kohly J. Matthiessen A. Schröder-Ritzrau 《International Journal of Earth Sciences》1995,84(1):108-136
A synoptic study is carried out to reconstruct the development of the plankton community in the late Quaternary in the Norwegian-Greenland Sea. It comprises quantitative analyses of coccolithophores, dinoflagellate cysts, diatoms and radiolarians. An actualistic approach is applied to evaluate the different fossil records of these plankton groups. The preliminary results of the current investigation are reported here.The composition and distribution of living communities of coccolithophores are presented as an example. A close relationship between the distribution of regional groups and surface water masses is observed. Seasonal vertical fluxes of coccolithophores and radiolarians through the water column show similar patterns within different years. However, diatoms are highly variable, both in absolute fluxes and species composition. The differentiation of sporadic and periodic processes is evident only after several years of observation. During settling and sedimentation biotic and abiotic processes such as grazing, dissolution and lateral transport alter the assemblages.Investigation of death assemblages in surface sediments reveals that in spite of these alteration processes the abundance and species distribution are related to surface water masses. Higher abundances and diversities are usually found in sediments underlying the warm Norwegian Current. Concentrations decrease to the north-west towards the cold polar water masses.The sediment assemblages of all groups are strongly altered relicts of former living communities. They are characterized by distinct changes in species composition and absolute abundances related to palaeo-oceanographic development. Their variation through the sedimentary record is used to distinguish four ecostratigraphic units during the late Weichselian and Holocene. 相似文献
6.
本文通过对南海中北部1 266个站位19种硅藻的生物地理分布格局及其对环境因子偏好的研究,查清了南海中北部沉积硅藻高分辨的空间展布特征,并探讨了硅藻分布与海洋环境因子的关系。南海北部陆架和西部陆架表层沉积硅藻以广温的半咸水潮间带种或沿岸种和咸水-半咸水浅海种为主,珠江口以东的粤东北部陆架Paralia sulcata呈集中分布,粤西北部陆架多样性最佳,Cyclotella stylorum相对富集,西部陆架则以Cyclotella striata占显著优势。北部陆坡和西部陆坡以热带浮游远洋种为主,其中Azpeitia nodulifera和Nitzschia marina分别在琼东南陆坡、西部陆坡和东北部陆坡占优势地位,Chaetoceros messanensis、Fragilariopsis doliolus集中分布于北部陆坡。深海盆以热带浮游远洋种为主,A.nodulifera最具优势,其次为N.marina,Thalassionema nitzschioides和Thalassiosira eccentrica在吕宋海峡入口、深海盆东部和东南部礼乐岛坡集中分布。硅藻种和环境因子的Pearson相关性分析和冗余分析表明,热带远洋种与表层海水温度显著正相关,广温广布种与温度和盐度呈一定正相关,多数沿岸种和浅海种与盐度显著负相关。硅藻组合与海洋流系控制下的环境因子关系密切。可分为6个硅藻组合,其中陆架区3个组合主要受到盐度和营养盐(NO3,PO4,SiO4)浓度的影响,陆坡区2个组合主要受表层海水温度、盐度和营养盐(PO4)浓度的影响,而深海盆硅藻组合主要受温度的影响。对比前人研究,本文提高了对南海沉积硅藻空间分布认识的分辨率,充实了研究相对薄弱的西部陆架和深海盆的最新资料,佐证并修正了前人基于少量数据而得出的硅藻组合分区认识,消弭了前人观点的分歧。生物因素和沉积过程会使沉积硅藻对环境因子变化的响应关系更为复杂。 相似文献
7.
Richard B. Brugam 《Quaternary Research》1980,13(1):133-146
Fossil diatom assemblages from a 12-m core from Kirchner Marsh were compared with modern surface assemblages from 159 Minnesota and labrador lakes using cluster analysis. The deepest levels of the core (spruce pollen zone 13,000 to 10,200 yr B.P.) resemble modern diatom assemblages from deep oligotrophic lakes of northeastern Minnesota. Diatom assemblages of the pine pollen zone (about 10,200 to 9500 yr B.P.) have few modern analogs. In the oak zone (9500 yr B.P. to present) after a brief pulse of diatom species indicative of eutrophication, the assemblages are dominated by species characteristic of shallow lakes, suggesting a drop in the lake water level during the prairie period (5500 to 7500 yr B.P.). Macrofossil data of W. A. Watts and T. C. Winter (1966, Geological Society of America Bulletin77, 1339–1360) show that this shift to shallow-water diatoms occurred when aquatic macrophytes appeared at the site in abundance. 相似文献
8.
T. V. Oreshkina 《Stratigraphy and Geological Correlation》2009,17(3):331-345
Diatom assemblages from the marine Paleogene of Western Kamchatka (the Kovachina, Viventek, and Kuluven formations) are studied. The shallow-water neritic assemblage from the Kovachina Formation of the Pyatibratskii Cape section is tentatively attributed to the middle Eocene, as it is lacking zonal index species. A high abundance and great taxonomic diversity are characteristic of diatoms from the upper part of the Viventek Formation in the Kovran River section. The zonal index species Cavitatus rectus identified here among the diatoms suggests that the respective assemblage is macerated from the synonymous diatom zone of the middle Oligocene (29.6?28.2 Ma). According to its taxonomic composition and structure, this assemblage is indicative of transgression environments and the presumable influence of the middle Oligocene climatic optimum. The Rocella gelida (upper part) and Thalassiosira praefraga diatom zones of the Oligocene-Miocene transition are established in the Kuluven Formation sediments of the Mt. Uvuch section in Kovachina Bay. 相似文献
9.
Cooper Sherri Rumer McGlothlin Sunghea Kim Madritch Michael Jones Daniel L. 《Estuaries and Coasts》2004,27(4):617-633
Sediment cores were collected from the Neuse and Pamlico River estuaries, North Carolina, at seven different sites, and the
data show strong anthropogenic influence on water quality. The sediments from these cores were dated using210Pb,137Cs,14C, and pollen horizon techniques. Specific parameters investigated include bulk density, sedimentation rates, diatom assemblage
changes, nutrient and trace metal flux, and vegetation changes as recorded in the pollen record. The greatest increases in
sedimentation, nutrient and metal flux and changes in diatom assemblages have occurred in the past 50–60 yr in the Pamlico
and Neuse. Diatom diversity has decreased and small planktonic forms have become dominant over time, most likely due to eutrophication
and increased turbidity and sedimentation. Major changes occur before phytoplankton surveys and monitoring were initiated.
Overall trends are similar to those found in Chesapeake Bay, although the time frame of major changes is more recent. Dominant
small planktonic diatom species differ between Chesapeake Bay and the Neuse and Pamlico. Variance in paleoecological indicators
between these mid-Atlantic estuaries may be due to geomorphology and land use history. 相似文献
10.
A. Yu. Gladenkov 《Stratigraphy and Geological Correlation》2006,14(1):73-90
Fossil diatoms from the Milky River Formation of the Sandy Ridge section, Alaska Peninsula are analyzed. Data on stratigraphic distribution of diatoms and silicoflagellates are presented. Based on presence of stratigraphically important forms (Neodenticula kamtschatica, Thalassiosira oestrupii, Cosmiodiscus insignis), the assemblages studied are correlated with the North Pacific Cenozoic diatom zones. An assemblage similar to that of subzone “b” of the Neodenticula kamtschatica Zone (Barron and Gladenkov, 1995) indicates the latest Miocene-initial early Pliocene (5.5-4.8 Ma) age of its host deposits. Additional species of biostratigraphic importance (Thalassiosira temperei, Th. latimarginata, and others) refine ages of different parts of the section. In particular, age of stratigraphically lowest beds bearing Astarte (mollusks valuable for establishing the Bering Strait opening) were dated at 5.5-5.4 Ma. Some paleogeographic inferences are made from analysis of composition of the diatom assemblages. 相似文献
11.
Abdelfattah A. ZALAT 《《地质学报》英文版》2018,92(1):354-366
A detailed analysis of the diatoms from the sedimentary sequence exposed in Abu Qada basin, west central Sinai, was used to determine the palaeoenvironmental changes during the Lower to Middle Miocene. A total of 85 diatom species and varieties belonging to 37 genera were identified from 154 samples collected throughout the stratigraphic succession. The lithological characters of the studied samples varied between sandstone, silty interbeds, sandy shales, shales, and terminated with anhydrite and limestones. These rock units are included in two lithostratigraphic formations (Rudies and Kareem), which are separated by a marked unconformity. The distribution and preservation of fossil diatoms in the sedimentary record are examined with the aim of outlining the temporal and spatial variation in the composition of the diatom assemblages, in order to estimate the changes in depositional environments during the Lower to Middle Miocene. The distributional pattern of the recorded diatom taxa distinguished four diatom eco-zones. The environment of each eco-zone is deduced and a proposed paleobathymetric change and depositional history of the Miocene sediments in the studied area are given. 相似文献
12.
G. N. Aleksandrova T. V. Oreshkina A. I. Iakovleva E. P. Radionova 《Stratigraphy and Geological Correlation》2012,20(4):380-404
The Paleocene-Eocene transition is one of the most remarkable Cenozoic periods coinciding with the global thermal maximum (PETM). Based on the complex biostratigraphic analysis of diatoms, silicoflagellates, and dinocysts, this global event is revealed in three sections of the Middle Trans-Urals region (Kamyshlov, Korkino, Chumlyak) represented by marine biosiliceous sediments of the Serov and Irbit formations. The interval of the Trinacra ventriculosa-Hemiaulus proteus-Coscinodiscus uralensis diatom zones is marked by the appearance of new genera Moisseevia, Solium, Fenestrella, Craspedodiscus, Podosira, Pseudotriceratium, intense radiations of Grunoweiella and Coscinodiscus, and development of extreme morphotypes among silicoflagellates. The defined diatom assemblages differ slightly from their coeval counterparts from the Middle Volga region, which casts doubt upon the assumed stable water exchange between these basins. On the contrary, the dinocyst assemblages are lacking zonal index species (Appectodinium homomorphum, A. augustum) and Apectodinium acme characteristic of the transitional Paleocene-Eocene strata in many worldwide localities. The facies settings of his period with intense vertical mixing and relatively low temperatures and salinity are characterized by the dominant role of dinocysts belonging to the genera Areoligera, Deflandrea, Spiniferites, and Operculodinium. 相似文献
13.
This study examined whetherMercenaria mercenaria (L.) (quahog) growth is influenced by variability in phytoplantkon community composition in the waters of Long Island, New York. Field studies conducted during 1999 and 2000 compared juvenile quahog growth and phytoplankton assemblages between West Sayville (WS), an embayment in Great South Bay along Long Island’s south shore where quahog landings have recently declined, and Oyster Bay (OB), an embayment on Long Island’s north shore where quahog landings are still high. Quahogs grew better at OB than WS during both study years. Centric diatoms were typically the dominant phytoplankton species at OB, and pennate diatoms and dinoflagellates characterized WS. At WS, the phytoplankton community consisted of heterotrophic dinoflagellates during a brown tide in 2000 and pennate diatoms afterward. Nanoflagellates were abundant (105–106 cells ml?1) at WS throughout the summer of 2000. Multiple regression analysis revealed a significant effect of site and temperature on individual clam biomass during both years, but brown tide was only significant during 2000. Biomass comparisons of dominant phytoplantkon taxa with laboratory physiology studies showed that 0B, with its abundance of centric diatoms, likely represented a more nutritional diet for quahogs than pennate diatoms, which were abundant at WS. Small flagellates, which were common at WS, may also have been important for sustaining growth during some months. Variability in plankton assemblages between OB and WS likely represented two distinct, diets that were critical influences on clam growth. 相似文献
14.
《Russian Geology and Geophysics》2007,48(4):361-370
We report results of an integrated study of volcanosedimentary rocks of the Middle-Late Miocene Dzhilinda Formation consisting of the prevolcanic sedimentary Lower Dzhilinda and volcanosedimentary Upper Dzhilinda subformations. The section was studied in three wells drilled near Lake Mukhal (Khoigot paleovalley, Vitim upland). The Dzhilinda sediments contain ubiquitous Alveolophora jouseana (Moiss.) Moiss. typical of Miocene environments. Deposition occurred in two main stages represented by different water (diatoms) and land (spores and pollen) plant communities. The upsection successive changes in diatom species are attendant with changes in pollen and spore assemblages. The K-Ar ages of lavas indicate that the mostly sedimentary lower section of the Dzhilinda Formation deposited between 12 and 14 Ma and the more volcanic upper section, with a lacustrine lens at base, formed at about 10.8–9.5 Ma. The isotope dating of volcanic rocks agrees with the ages inferred from the diatom and spore-pollen analyses. The prevolcanic Lower Dzhilinda subformation deposited during the Middle Miocene climate optimum. The stratigraphy, lithology and facies of sediments suggest that the Dzhilinda deposition was associated with the development of a deep freshwater lake in the conditions of active tectonism and volcanism. 相似文献
15.
《第四纪科学杂志》2017,32(3):396-415
16.
The present study encompasses a detailed investigation of downcore Holocene foraminifera and their assemblages to comprehend the ecology of the Bay of Bengal and compare it with that of the South China and Sulu Seas, at the same depth for all the three water bodies. Based on temperature and dissolved oxygen profiles, benthic foraminiferal abundance, and species diversity values, it is inferred that the Bay of Bengal is much better ventilated than either the South China or the Sulu Sea. The planktic/benthic (P/B) ratios are extremely low when compared with those reported elsewhere in the world. The absolute dominance of benthic foraminiferal species over their planktic counterparts is attributed to the effect of fragmentation and dissolution of the latter, as they are relatively more susceptible to this process. The very low P/B values are also indicative of water depth below the lysocline in this part of the Bay of Bengal. 相似文献
17.
珠江口黄茅海河口湾的表层沉积物100个站位样品中共发现有孔虫21属36种、介形虫16属20种。优势种组合分别为Ammonia beccarii-Quinqueloculina akneriana rotunda-Cavarotalia annectens-Elphidium advenum和Neomonoceratina delicata-Sinocytheridea impressa-Bicornucythere bisanensis。有孔虫及介形虫的丰度和分异度均表现出“北低南高”,即口门低、向海高的特点。样品中有孔虫和介形虫属种的去趋势对应分析（DCA）表明,盐度是影响该区有孔虫和介形虫分布的最重要因素,其次是水动力条件,水深对有孔虫和介形虫的分布也有一定影响,但并非主要控制性因素。由于受径流影响较大,河口湾北部的水体盐度较低、径流动力较强,不利于有孔虫和介形虫的生存,导致其丰度及分异度均较低。河口湾南部水体盐度升高,潮流动力较强,同时受众多岛屿屏障作用,环境较为稳定,有孔虫和介形虫的丰度和分异度均迅速上升。 相似文献
18.
白令海表层沉积物中硅质生物的变化及其环境控制因素 总被引：6，自引：2，他引：4
中国首次北极科学考察在白令海采取了12个表层沉积物样品, 其中对硅质生物和陆源碎屑的详细研究发现, 它们主要由硅藻、放射虫和海绵骨针组成.其中, 硅藻在样品中的丰度均占绝对优势, 高出放射虫和海绵骨针一个数量级.它们与环境控制因素关系的分析表明, 硅藻、放射虫和海绵骨针丰度的高低及其保存程度与深度、温度、盐度和受大规模季节性气候变化控制的表层海水的高营养和高生产力, 以及陆源物质输入的变化密切相关.这一研究结果对白令海第四纪的古气候与古海洋学研究具有十分重要的意义. 相似文献
19.
香港西博寮海峡WB7孔的第四纪沉积及硅藻研究 总被引：1，自引：1，他引：1
香港西搏寮海峡ＷＢ７孔第四纪沉积物中共有硅藻５４属，１８６个分类单位，该硅藻生物群以沿岸潮间带和近岸浅海种为主，伴有热性，暖热性浮游硅藻。依据硅藻在剖面中的分布特征，丰度及百分比含量变化，自下而上可划分出６个硅藻组合带。并明显反映该沉积时期的古气候与古环境特征，其中第５，６，带相当于全新世，其余４个带均属更新世。 相似文献
20.
The relative abundance of diatom species in different habitats can be used as a tool to infer prior environmental conditions and evaluate management decisions that influence habitat quality. Diatom distribution patterns were examined to characterize relationships between assemblage composition and environmental gradients in a subtropical estuarine watershed. We identified environmental correlates of diatom distribution patterns across the Charlotte Harbor, Florida, watershed; evaluated differences among three major river drainages; and determined how accurately local environmental conditions can be predicted using inference models based on diatom assemblages. Sampling locations ranged from freshwater to marine (0.1–37.2 ppt salinity) and spanned broad nutrient concentration gradients. Salinity was the predominant driver of difference among diatom assemblages across the watershed, but other environmental variables had stronger correlations with assemblages within the subregions of the three rivers and harbor. Eighteen indicator taxa were significantly affiliated with subregions. Relationships between diatom taxon distributions and salinity, distance from the harbor, total phosphorus (TP), and total nitrogen (TN) were evaluated to determine the utility of diatom assemblages to predict environmental values using a weighted averaging-regression approach. Diatom-based inferences of these variables were strong (salinity R 2?=?0.96; distance R 2?=?0.93; TN R 2?=?0.83; TP R 2?=?0.83). Diatom assemblages provide reliable estimates of environmental parameters on different spatial scales across the watershed. Because many coastal diatom taxa are ubiquitous, the diatom training sets provided here should enable diatom-based environmental reconstructions in subtropical estuaries that are being rapidly altered by land and water use changes and sea level rise. 相似文献