共查询到20条相似文献,搜索用时 15 毫秒
1.
渤海莱州湾表层沉积物中底栖有孔虫分布特征及其环境意义 总被引:2,自引:0,他引:2
对渤海莱州湾海域240个站位表层沉积物中底栖有孔虫群落进行了分析,共鉴定常见的底栖有孔虫42种。结果表明,莱州湾表层沉积物中底栖有孔虫主要以玻璃质壳为主(平均丰度达70.9%),瓷质壳含量次之,胶结壳含量最低;玻璃质壳占有孔虫全群的百分含量,随水深的增加而增加;从黄河口向外海方向,有孔虫分异度和丰度都逐渐增大。该海域底栖有孔虫平面分布的主要控制因素为盐度和底质沉积物类型,大体可分为两个组合分区,I区为Ammonia beccarii-Quinqueloculina spp.组合,代表盐度较低的近岸海陆过渡浅水环境;II区为Cribrononionsub-incertum-Protelphidium tuberculatum组合,代表盐度较高的远岸内陆架环境。 相似文献
2.
《Marine Micropaleontology》1996,28(2):171-197
A census count of Rose Bengal stained benthic foraminifera from the surface area on top of a 2 to 6 cm thick ashfall layer at three deep water stations along the western margin of the Philippines exhibits a unique assemblage composition of benthic foraminifera. The total number of benthic foraminifera is low and the ratio of living individuals to empty tests is high. Specific diversity is low, with a significant dominance of infaunal morphotypes including species of the genus Reophax (R. scorpiurus, R. bilocularis and R. dentaliniformis), which are regarded as successful recolonizers. Assemblages below the ash layers are diverse and contain many epifaunal suspension-feeding agglutinated and calcareous foraminifera. The 1991 Mt. Pinatubo eruption caused mass mortality of benthic foraminifera in a vast area of the eastern South China Sea followed by step-wise recolonization of the ash substrate. Three years after the eruption, the benthic foraminiferal community structure is still far from recovery to background levels. 相似文献
3.
《Marine Micropaleontology》2006,58(2):103-113
Sediments from the western and southern part of the Arabian Sea were collected periodically in the spring intermonsoon between March and May 1997 and additionally at the end of the Northeast Monsoon in February 1998. Assemblages of Rose Bengal stained, living deep-sea benthic foraminifera, their densities, vertical distribution pattern, and diversity were analysed after the Northeast Monsoon and short-time changes were recorded. In the western Arabian Sea, foraminiferal numbers increased steadily between March and the beginning of May, especially in the smaller size classes (30–63 μm, 63–125 μm). At the same time, the deepening of the foraminiferal living horizon, variable diversity and rapid variations between dominant foraminiferal communities were observed. We interpret these observations as the time-dependent response of benthic foraminifera to enhanced organic carbon fluxes during and after the Northeast Monsoon. In the southern Arabian Sea, constant low foraminiferal abundances during time, no distinctive change in the vertical distribution, reduced diversity, and more stable foraminiferal communities were noticed, which indicates no or little influence of the Northeast Monsoon to benthic foraminifera in this region. 相似文献
4.
Cretaceous and early Paleocene benthic foraminifera were studied from one section along the western Gaj River, southern Balochistan, Pakistan, to reconstruct the paleoenvironment of the Tethys Sea during the Indian-Asian contact. We recognize three lithostratigraphic units in ascending order: the Mughal Kot Formation, the Pab Sandstone, and the Jamburo Group. Both the Maastrichtian Mughal Kot Formation, which consists of shale with grey marly limestone, and the Maastrichtian Pab Sandstone, which consists of quartzose sandstone, indicate an open ocean environment as they have diversified planktic and benthic foraminiferal assemblages. The Maastrichtian-Paleocene Jamburo Group, consisting of dark grey, calcareous shale and marlstone with some sulfide grains, is characterized by low diversities of benthic assemblages. The change to the lower diversities may be associated with the development of poor circulation of deeper water that was caused by narrowing of the Tethys Sea.The Trochammina spp. Assemblage from the Jamburo Group, which can be correlated with flysch-type agglutinated foraminiferal assemblages, has a low benthic species diversity, indicating an unfavorable condition for calcareous foraminifera because of the development of oxygen-depleted water. The absolute abundance of agglutinated specimens shows a remarkable change from low numbers in the Maastrichtian to high ones in the Paleocene. The benthic foraminiferal evidence supports the hypothesis that the collision of the Asian and Indian plates occurred near the end of the Cretaceous. 相似文献
5.
Paleontological and biostratigraphical studies on carbonate platform succession from southwest Iran documented a great diversity of shallow-water benthic foraminifera during the Oligocene–Miocene. Larger foraminifera are the main means for the stratigraphic zonation of carbonate sediments. The distributions of larger benthic foraminifera in two outcrop sections (Abolhayat and Lali) in the Zagros Basin, Iran, are used to determine the age of the Asmari Formation. Four assemblage zones have been recognized by distribution of the larger benthic foraminifera in the study areas. Assemblage 3 (Aquitanian age) and 4 (Burdigalian age) have not been recognized in the Abolhayat section (Fars area), due to sea-level fall. The end Chattian sea-level fall restricted marine deposition in the Abolhayat section and Asmari Formation replaced laterally by the Gachsaran Formation. This suggests that the Miocene part of the formation as recognized in the Lali section (Khuzestan area) of the Zagros foreland basin is not present in the Abolhayat outcrop. The distribution of the Oligocene larger benthic foraminifera indicates that shallow marine carbonate sediments of the Asmari Formation at the study areas have been deposited in the photic zone of tropical to subtropical oceans. Based on analysis of larger benthic foraminiferal assemblages and microfacies features, three major depositional environments are identified. These include inner shelf, middle shelf and outer shelf. The inner shelf facies is characterized by wackestone–packstone, dominated by various taxa of imperforate foraminifera. The middle shelf is represented by packstone–grainstone to floatstone with a diverse assemblage of larger foraminifera with perforate wall. Basinwards is dominated by argillaceous wackestone characterized by planktonic foraminifera and large and flat nummulitidae and lepidocyclinidae. Planktonic foraminifera wackestone is the dominant facies in the outer shelf. 相似文献
6.
Oliver Friedrich 《Revue de Micropaléontologie》2010,53(3):175-108
Oceanic Anoxic Events (OAEs) are a widespread, recurring and well-studied feature of the mid-Cretaceous greenhouse climate, reflecting severe perturbations in Earth's climate and oceanography. To investigate bottom-water environments before, during and after these OAEs and to understand the dynamic fluctuations of seafloor environments, benthic foraminifera are a commonly employed tool. Here, a review of the response of benthic foraminiferal assemblages to OAEs (i.e., OAEs 1a, 1b, 1d, 2, and 3) will be given. I will discuss in detail how benthic foraminifera can be used to identify the paleoclimatic and paleoceanographic mechanisms responsible for OAE formation. The main feature of benthic foraminiferal assemblages during oceanic anoxic events is a dramatic decrease in both diversities and abundances or their total absence. However, some studies record the permanent occurrence of benthic foraminifera throughout OAEs or short-term repopulation events. These patterns clearly indicate that mid-Cretaceous OAEs are complex events. The paradox of anoxic (and even euxinic) conditions during OAEs coincident with the occurrence of benthic foraminifera (here called the “anoxic benthic foraminifera” paradox) is most readily explained by the sampling (and therefore temporal) resolution of typical foraminiferal studies that have homogenized hundreds to thousands of years in a single sample. 相似文献
7.
Detritivorous macroorganisms have important functions in nutrient remineralization and may exert significant predation pressure on meiofaunal communities. We have examined food excrements of detritus grazing holothuroids off Elba Island (Mediterranean Sea) to investigate whether ingested foraminifera survive the passage through the digestive tract. Our findings provide evidence that some benthic foraminifera pass through the complete digestive tract without being harmed by its predators. Sediment-feeding holothurians may thus affect microdistributional processes ultimately resulting in an allochthonous redistribution of foraminifera within the environment. 相似文献
8.
《Marine Micropaleontology》2005,58(1):13-30
Fluctuations in abundance, diversity and species composition of benthic foraminifera from two sites of the northern and southern Red Sea indicate strong variability of deep-sea ecosystems during the last four glacial to interglacial cycles. In total, five and four different benthic foraminiferal assemblages have been identified in the northern core and southern core, respectively. Comparison with recent faunas from the Red Sea and adjacent oceans allowed the reconstruction of temporal changes in deep-water ventilation, salinity and food availability at the seafloor. Generally, the abundance of infaunal and miliolid taxa increase during glacial intervals indicating increased organic matter fluxes, oxygen decrease and salinity increase in deep waters during these times. These fluctuations are attributed to enhanced oxygen consumption rates and temporarily reduced deep-water formation in the northern Red Sea during glacial intervals. The recorded environmental changes are a reflection of both high- and low-latitude climate changes. The northern Red Sea is mainly influenced by glacio-eustatic sea level fluctuations that control deep-water formation rates and by mid-latitude climate changes of the Mediterranean region that control surface productivity. In contrast, deep-sea ecosystem variability of the southern Red Sea is additionally influenced by low-latitude climate changes attributed to the NE monsoon intensity that drives the inflow of nutrient-rich surface waters from the Gulf of Aden. These results demonstrate the high sensitivity of deep-sea ecosystems of the Red Sea to both global and regional climate changes. 相似文献
9.
10.
This review presents data on how natural and anthropogenic factors affect species composition, abundance, and test morphology of benthic foraminifera of the world oceans. Major emphasis is placed on high sensitivity of foraminifera to changes in the state of the environment, particularly in nearshore zones under anthropogenic impact. It is shown that benthic foraminifera can provide indicators of environmental conditions in marine ecosystems. The effects of mollusk and salmon aquaculture activities on the composition and distribution of foraminifera are considered. It is stressed that a distinction must be made between foraminiferal test morphology variations in response to natural and anthropogenic impacts. 相似文献
11.
《微体古生物学报》2014,(2)
本文对南黄海西北陆架边缘的300个表层沉积物样品中的底栖有孔虫数据,与相应站位的水深、底层水温、盐度、沉积物粒度、有机碳含量等环境参数作了分析研究。除趋势对应分析(DCA)、典型对应分析(CCA)表明有孔虫种群分布与水深、夏季底层水温(Ts)和冬季底层水盐度(Sw)之间存在着显著的数值对应关系。利用加权平均偏最小二乘回归方法(WA-PLS)建立了底栖有孔虫数据与上述环境因子之间的数值转换函数。水深、Ts与Sw转换函数的预测均方根误差(RMSEP)分别是10.8%、11.5%和12.5%,与利用其他指标建立的此类转换函数水平(8%—20%)相当。利用此类统计建模方法建立近岸底栖有孔虫分布与浅海环境因子之间的数值关系是一项新的尝试,结果表明在我国近海底层水体古环境研究中底栖有孔虫转换函数是一种具有一定潜力的研究方法。 相似文献
12.
Amphisteginid foraminifera are larger symbiont-bearing foraminifera that are abundant in tropical and subtropical reef and shelf regions of the world’s oceans. There is now unequivocal evidence that climate change has led to an expansion of tropical belts. As temperatures rise, surface isotherms are shifting poleward and habitat ranges are moving towards higher latitudes. Fueled by substantial warming, the Mediterranean has been identified as one of the most severely affected areas. This study documents for the first time that amphisteginid foraminifera have now crossed the Strait of Otranto and invaded the eastern Adriatic coast along southern Albania. Sampling on the opposite side along the southern part of the Italian boot shows, however, that amphisteginid foraminifera have not yet colonized the western coast of the Adriatic. The asymmetric invasion of the Adriatic displays spatial heterogeneity, where the progressive colonization follows the major surface currents with a northerly flow along the eastern coast and a southerly return along the western coastline. Previous sampling along Ionian Sea sample sites provides a baseline chronology allowing computations of range expansion rates. The observed recent rate of range expansion in Amphistegina is computed between 4.0 and 10 km/year?1 and provides strong support for current species model projections. Based on the new data, the range boundary shift is projected to lead to a total northward range expansion of 5.2° latitude in the year 2100. The latitudinal range extension computed for the Mediterranean is thus almost twice as large as those computed for the southern hemisphere. The ongoing range extension into new areas of the Mediterranean Sea is shown to trigger changes in community structures with potential consequences for ecosystem functioning. Numerical abundances and impacts of invasive amphisteginids are greatest at shallow depths <20 m. Evidence is now accumulating that the invasion of amphisteginid foraminifera results in (1) a loss of benthic foraminiferal biodiversity, (2) alterations of foraminiferal community structures and (3) shifts in abundances of functional groups of foraminifera. 相似文献
13.
Living benthic foraminifera of the Okhotsk Sea: Faunal composition,standing stocks and microhabitats
《Marine Micropaleontology》2009,70(3-4):314-333
Live (Rose Bengal stained) benthic foraminifera were investigated in surface sediment samples from the Okhotsk Sea to reveal the relationship between faunal characteristics and environmental parameters. Live benthic foraminifera were quantified in the size fraction > 125 µm in the upper 8 cm of replicate sediment cores, recovered with a multicorer at five stations along the Sakhalin margin, and at three stations on the southwestern Kamchatka slope. The stations are from water depths between 625 to 1752 m, located close or within the present Okhotsk Sea oxygen minimum zone, with oxygen levels between 0.3 and 1.5 ml l- 1. At the high-productivity and ice-free Kamchatka stations, live benthic foraminifera are characterized by maximal standing stocks (about 1700-3700 individuals per 50 cm2), strong dominance of calcareous species (up to 87-91% of total live faunas), and maximal habitat depths (down to 5.2-6.7 cm depth). Vertical distributions of total faunal abundances exhibit a clear subsurface maximum in sediments. At the Sakhalin stations, which are seasonally ice-covered and less productive, live benthic foraminifera show lower standing stocks (about 200-1100 individuals per 50 cm2), lower abundance of calcareous species (10-64% of total live faunas), and shallower habitat depths (down to 2.5-5.4 cm depth). Faunal vertical distributions are characterized by maximum in the uppermost surface sediments. It is suggested that 1) lower and strongly seasonal organic matter flux, caused by the seasonal sea ice cover and seasonal upwelling, 2) lower bottom water oxygenation (0.3-1.1 ml l- 1), and 3) more pronounced influence of carbonate undersaturated bottom water along the Sakhalin margin are the main factors responsible for the observed faunal differences. According to species downcore distributions and average living depths, common calcareous species were identified as preferentially shallow, intermediate and deep infaunal. Foraminiferal microhabitat occupation correlates with the organic matter flux and the depth of the oxygenated layer in sediments. 相似文献
14.
Natalia Bubenshchikova Dirk Nürnberg Lester Lembke-Jene Galina Pavlova 《Marine Micropaleontology》2008,69(3-4):314-333
Live (Rose Bengal stained) benthic foraminifera were investigated in surface sediment samples from the Okhotsk Sea to reveal the relationship between faunal characteristics and environmental parameters. Live benthic foraminifera were quantified in the size fraction > 125 µm in the upper 8 cm of replicate sediment cores, recovered with a multicorer at five stations along the Sakhalin margin, and at three stations on the southwestern Kamchatka slope. The stations are from water depths between 625 to 1752 m, located close or within the present Okhotsk Sea oxygen minimum zone, with oxygen levels between 0.3 and 1.5 ml l- 1. At the high-productivity and ice-free Kamchatka stations, live benthic foraminifera are characterized by maximal standing stocks (about 1700-3700 individuals per 50 cm2), strong dominance of calcareous species (up to 87-91% of total live faunas), and maximal habitat depths (down to 5.2-6.7 cm depth). Vertical distributions of total faunal abundances exhibit a clear subsurface maximum in sediments. At the Sakhalin stations, which are seasonally ice-covered and less productive, live benthic foraminifera show lower standing stocks (about 200-1100 individuals per 50 cm2), lower abundance of calcareous species (10-64% of total live faunas), and shallower habitat depths (down to 2.5-5.4 cm depth). Faunal vertical distributions are characterized by maximum in the uppermost surface sediments. It is suggested that 1) lower and strongly seasonal organic matter flux, caused by the seasonal sea ice cover and seasonal upwelling, 2) lower bottom water oxygenation (0.3-1.1 ml l- 1), and 3) more pronounced influence of carbonate undersaturated bottom water along the Sakhalin margin are the main factors responsible for the observed faunal differences. According to species downcore distributions and average living depths, common calcareous species were identified as preferentially shallow, intermediate and deep infaunal. Foraminiferal microhabitat occupation correlates with the organic matter flux and the depth of the oxygenated layer in sediments. 相似文献
15.
The distributional patterns of recent benthic foraminifera have been studied in the Adriatic Sea near the Kornati Islands Middle Dalmatia at a submarine cliff of 70 m height. One of the submarine cliffs is exposed to the open sea, the other one to the channel. Diagrams show the composition of the foraminiferal fauna with respect to the highest systematic categories to the species level, as well as the distribution and abundance of the most common foraminifera of the superfamilies Lituolacea and Miliolacea. These diagrams can be used for bathymetric interpretations and for the definition of ecological niches. Nearly half of the species are known also from Ancient environments. 相似文献
16.
Distribution patterns of planktonic foraminifera in four sediment cores from the Red Sea are studied. The most common species are Globigerinoides ruber, G. sacculifer, Globigerinella siphonifera and Orbulina universa. G. ruber and G. sacculifer show opposite trends of distribution in the sediment cores. Abundance of the foraminifera during the glacial periods suggests that the connection of the Red Sea to the Indian ocean was not completely interrupted and the salinity conditions were not extreme.However, higher salinities appear to have existed in the northern Red Sea, where most of the planktonic foraminifera that occur in the southern Red Sea are absent. It is inferred that the salinity in the southern Red Sea during the glacial period was less than 50%, whereas higher salinity might have existed in the north where the influence of the Indian Ocean was minimal. 相似文献
17.
The Tale-Zang Formation in Zagros Mountains (south-west Iran) is a Lower to Middle Eocene carbonate sequence. Carbonate sequences
of the Tale-Zang Formation consist mainly of large benthic foraminifera (e.g. Nummulites and Alveolina), along with other skeletal and non-skeletal components. Water depth during deposition of the formation was determined based
on the variation and types of benthic foraminifera, and other components in different facies. Microfacies analysis led to
the recognition of ten microfacies that are related to four facies belts such as tidal flat, lagoon, shoal and open marine.
An absence of turbidite deposits, reefal facies, gradual facies changes and widespread tidal flat deposits indicate that the
Tale-Zang Formation was deposited in a carbonate ramp environment. Due to the great diversity and abundance of larger benthic
foraminifera, this carbonate ramp is referred to as a “foraminifera-dominated carbonate ramp system”. Based on the field observations,
microfacies analysis and sequence stratigraphic studies, three third-order sequences in the Langar type section and one third-order
sequence in the Kialo section were identified. These depositional sequences have been separated by both type-1 and type-2
sequence boundaries. The transgressive systems tracts of sequences show a gradual upward increase in perforate foraminifera,
whereas the highstand systems tracts of sequences contain predominantly imperforate foraminifera. 相似文献
18.
The abundance and structure of the foraminifera community have been investigated. The role of agglutinating and secreting species in bottom sediments of the deep trenches of the Kara Sea has been studied. It has been found that the abundance and dominance of the agglutinated foraminifera Saccorhiza ramosa depend on the depth of the sea and are related to the genetic type of origin of such sediments. A correlation has been revealed between the distribution of S. ramosa and the concentrations of natural radionuclides (226Ra, 232Th, and 210Pb) in bottom sediments. The degree of dominance of S. ramosa in the community of benthic foraminifera increases along with natural radioactivity. 相似文献
19.
Deep-sea benthic foraminifera, planktic foraminifer Globigerina bulloides and pteropods have been quantitatively analysed in 451 samples from Ocean Drilling Program (ODP) Hole 716A, to understand
both surface and deep-sea palaeoceanographic changes in the equatorial Indian Ocean basin during the late Quaternary (∼444–151
Kyrs). Benthic foraminifera were analysed from >125 μm size fraction whereas Globigerina bulloides and pteropods were analysed from >150 μm size fraction. Factor analysis of most dominant benthic foraminiferal species over
the studied time span made it possible to identify three biofacies characterizing distinct deep-sea environmental settings
at Hole 716A. The environmental interpretation of each species is based on the ecology of recent deep-sea benthic foraminifera.
The faunal record indicates fluctuating deep-sea conditions including changes in surface productivity, organic food supply
and deep-sea oxygenation linked to changing wind intensities. These changes are pronounced on glacial-interglacial time scales
driven by summer monsoon winds. 相似文献
20.
《Marine Micropaleontology》2009,72(3-4):97-112
Ninety-five species and 19 genera of cosmopolitan, deep-sea benthic foraminifera belonging to the families Pleurostomellidae, Stilostomellidae and Nodosariidae, became extinct during the Late Pliocene–Middle Pleistocene. Only 50% of these (44 species) were present in the Pliocene or Pleistocene of the deep Mediterranean Sea (ODP Sites 654, 966, 967, 975, 976), being those which had successfully migrated in via the Strait of Gibraltar from the deep Atlantic following the annihilation of the Mediterranean deep-sea fauna during the Late Miocene Messinian Crisis. Most colonisation occurred within the first 0.8 myrs (5.3–4.5 Ma) after re-establishment of the Mediterranean–Atlantic link, with possibly a second lesser period of immigration in the Late Pliocene (3.4–3.0 Ma). We infer that colonisations may have been fortuitous and few in number, as some common members of the group in the Atlantic never succeeded in establishing in the Mediterranean Sea. There is no evidence of any new immigration events during the Pleistocene, implying that the present anti-estuarine circulation may have been in place throughout this period. Our studies suggest that these deep-water, low-oxygen-tolerant foraminifera survived the many periods of deep-water sapropel formation in the Pliocene–Early Pleistocene, possibly in somewhat shallower (~ 500 m) refuges with dysoxic, rather than anoxic conditions.The Pliocene–Pleistocene stratigraphic record of this group of elongate, cylindrical benthic foraminifera with constricted and specialised apertures is similar in the west and east Mediterranean basins. The group declined in abundance (flux) and diversity in two pulses, during the Late Pliocene (3.1–2.7 Ma) and the late Early Pleistocene (1.3–1.0 Ma) in concert with global, southern-sourced, deep-water sites (AABW, CPDW) and earlier than the single decline (1.0–0.6 Ma) in global, intermediate water sites (uNADW, AAIW). All species, with one possible exception, disappeared earlier in the Mediterranean than globally. The highest occurrence of any species of this group in Mediterranean sites was 0.8–0.43 Ma, comparable with 0.7–0.2 Ma outside with the youngest survivors being in abyssal, deep-water.Thus, despite the unusual oceanographic conditions and isolation, the deep Mediterranean Sea was in this case neither the centre for the evolution of new species nor a refuge where species survived after they had disappeared elsewhere. 相似文献