Showing papers on "Foraminifera published in 1969"
TL;DR: Diversity peaks occur at abyssal depths of greater than 2500 meters and 100 to 200 meters and the peak at 35 to 45 meters is due to species equitability, whereas the other two peaks correspond to an increase in the number of species.
Abstract: Maximum species diversity occurs at abyssal depths of greater than 2500 meters. Other diversity peaks occur at depths of 35 to 45 meters and 100 to 200 meters. The peak at 35 to 45 meters is due to species equitability, whereas the other two peaks correspond to an increase in the number of species.
459 citations
TL;DR: The mean oxygen-18 content of continental ice sheets during the last glacial maximum is estimated to δO18=-30 per mille or less, and the consequent change in the isotopic composition of the oceans at that time to 1.2 per milne, which means that Emiliani's "paleotemperature" curve rather depicts the amount of ice on the continents in excess of that present today.
Abstract: The mean oxygen-18 content of continental ice sheets during the last glacial maximum is estimated to δO 18 =-30 per mille or less, and the consequent change in the isotopic composition of the oceans at that time to 1.2 per mille or more. This means that at least 70 percent of the oxygen-18 variations found in shells of planktonic foraminifera from deep-sea cores between times of glacial maximums and minimums are due to isotopic changes in ocean water, and at most 30 percent to changes in ocean surface temperature. Hence, Emiliani9s "paleotemperature" curve rather depicts the amount of ice on the continents in excess of that present today. In this sense it may be renamed a "paleoglaciation" curve.
223 citations
TL;DR: According to the present interpretation, the iLerative patterns reflect major changes in the dynamic structure of surface waters and it is suggested that thermal barriers were degraded during times of reduction and the oceans were uniformly cool during the radiations.
Abstract: The general aspects of planktonic foraminiferal radiation durilng the Cenozoic are shown by the distributional patterns of several morphotypic groups. There were two major radiations, one occurring during the Paleogene, the other during the Neogene. The radiations followed severe reductions in diversity which occurred at the close of the Cretaceous and again during the mid-Tertiary. Distributional patterns are iterative, and the Neogene radiation is essentially a repetition of what occurred during the Paleogene. According to the present interpretation, the iLerative patterns reflect major changes in the dynamic structure of surface waters. By analogy with the distribution of the modem fauna, it is suggested that thermal barriers were degraded during times of reduction and the oceans were uniformly cool. During the radiations thermal gradients were restored and the structure of the surface waters was essentially as it is today.
166 citations
TL;DR: Morphologic and taxonomic rates, negative values in late Eocene, early Oligocene, and late Miocene-Pleistocene, correlations with paleotemperatures as discussed by the authors.
Abstract: Morphologic and taxonomic rates, negative values in late Eocene, early Oligocene, and late Miocene-Pleistocene, correlations with paleotemperatures
157 citations
TL;DR: Foraminifera abundance in surface waters typically ranges from 1 or less to 100,000,000 specimens per 1000 m3, depending largely on the sampling gear used as mentioned in this paper.
107 citations
94 citations
TL;DR: The Upper Cretaceous strata along the west side of the Sacramento Valley and northern San Joaquin Valley contain a diversified and well-preserved fauna of planktonic foraminifera as mentioned in this paper.
Abstract: Upper Cretaceous strata along the west side of the Sacramento Valley and northern San Joaquin Valley contain a diversified and well-preserved fauna of planktonic foraminifera. Fifty-six of the stratigraphically important species of this fauna are herein described and illustrated. Three species are described as new.
67 citations
TL;DR: Foraminifera were most abundant in epiphytic communities of Enteromorpha in early summer and later spread to Zostera, Zanichellia, Ulva, Polysiphonia, and Ceramium, while patches of decaying EnteromOrpha had the greatest standing crop of foraminiferA and low species diversity index.
Abstract: During the summers of 1966 and 1967, 12 field trips were made to stations in North Sea Harbor, Southampton, Long Island (USA). From representative locations, 228 small samples of larger algae and their epiphytes (∼0.2 g dry weight) were taken aseptically. Enteromorpha intestinalis, the most widely distributed aquatic plant, was the most frequently collected. The large standing crop of Zostera marina and Zanichellia palustris was also sampled. Foraminifera were most abundant in epiphytic communities of Enteromorpha in early summer and later spread to Zostera, Zanichellia, Ulva, Polysiphonia, and Ceramium. Foraminifera were rarely found in epiphytic communities of Fucus or Codium. By summers' end Enteromorpha rarely had a standing crop of foraminifera. One of the most abundant foraminiferan species, Protelphidium tisburyensis, was found most frequently on Enteromorpha; Quinqueloculina spp occurring on Enteromorpha, less frequently. Ammonia beccarri and Elphidium spp were abundant in the environment, and showed little substrate preference. Patches of decaying Enteromorpha had the greatest standing crop of foraminifera and low species diversity index (0.581). Young green patches had a much higher species diversity index (0.94). Indices for Zostera, Zanichellia, Polysiphonia, Fucus, Ulva and Codium were, respectively, 0.82, 0.99, 0.86, 0.70, 0.77, and 0.196. No correlation was found between epiphytic community weight and total number of foraminifera recovered. The standing crop of epiphytes/g substrate dry weight was lower at some field stations; possibly explained by stronger current. Of the total samples, 50.4% were positive, with an average of 18 foraminifera/sample, or 40 foraminifera/g substrate plant and epiphytes. Twenty six samples were classified as bloom with 50 or more forams (57 to 425)/sample. Species diversity indices for these blooms ranged from 0.38 to 1.12. Ammonia beccarii was the dominant form in 18 blooms, Allogromia laticollaris and Protelphidium tisburyensis in 3; Elphidium incertum, Quinqueloculina seminulum and Trochammina inflata in 1 each.
65 citations
01 Jan 1969
TL;DR: Foraminifera and pteropod shells were found to have a beginning isotopic re-equilibration with the hot brine of the Red Sea during the last 80,000 to 100,000 years.
Abstract: Carbon and oxygen isotope ratios of foraminifera and pteropod shells show considerable fluctuations with depth in all cores investigated. Distinct changes in the isotope ratios at certain depths can be correlated among cores. Foraminifera tests deposited in the Discovery and Atlantis II Deeps during the last 10,000 years show evidence of a beginning isotopic re-equilibration with the hot brine. Older deposits show no such effect, suggesting a maximum age of the brine of about 10,000 years. The isotopic data strongly suggest the repeated occurrence of periods of evaporation in the Red Sea during the last 80,000 to 100,000 years. It seems likely that these periods coincided with those of lowered sea level which severely restricted the exchange of water between the Red Sea and the Indian Ocean. Alternatively the reduced exchange could have been caused by tectonic activity near the Strait of Bab el Mandeb.
54 citations
01 Jan 1969
TL;DR: In this article, distributional patterns among planktonic foraminifera studied in 20 deep sea cores were found to reflect late Pleistocene and Holocene climatic fluctuations in the Red Sea.
Abstract: Late Pleistocene and Holocene climatic fluctuations in the Red Sea are reflected in distributional patterns among planktonic foraminifera studied in 20 deep sea cores. Fluctuating percentages in two species, Globigerinoides ruber and G. sacculifer, have allowed the recognition of four biostratigraphic assemblage zones spanning the past 80,000 years. The youngest Zone, A, corresponds to the Holocene (base dated at ca. 11,000 years B.P.) is characterized by the dominance of Globigerinoides sacculifer, and represents the establishment of a normal Indian Ocean fauna following the Wurm glaciation.
45 citations
TL;DR: Early and middle Tertiary deep-sea carbonates from the equatorial Pacific differ in both texture and depth distribution from younger deposits as discussed by the authors, and have median grain diameters very close to 5 microns.
Abstract: Early and middle Tertiary deep-sea carbonates from the equatorial Pacific differ in both texture and depth distribution from younger deposits. Pre-Pliocene carbonates are well sorted. They are dominated by the remains of nannoplankton, and have median grain diameters very close to 5 microns. In contrast, Pliocene and Quaternary deposits are poorly sorted. They are frequently rich in the tests of Foraminifera, and have median diameters ranging from about 1 to more than 60 microns (part of the variation probably resulting from sorting at, or near, the sea floor). The calcite compensation level, now close to 4700 m, has risen from a depth of more than 5200 m since the Oligocene. The rise reflects,at least in part, the effect of decreasing bottom water temperatures on the solubility of calcium carbonate.
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TL;DR: The authors defined a species concept based on a representative sample of mature phenotypes and applied it to Pliocene planktonic foraminifera, genetic and environmental implications, high accuracy stratigraphic zonation.
Abstract: Species concept redefined based on representative sample of mature phenotypes, application to Pleistocene planktonic foraminifera, genetic and environmental implications, high accuracy stratigraphic zonation, North America
TL;DR: Anticipated pole-to-equator diversity and dominance gradients in the open ocean are virtually eliminated by the stronger trends of the vigorous subtropical North Atlantic gyre.
Abstract: Foraminferal dominance values above 50 percent and associated diversity minimums in surface sediments of the North Atlantic coincide with past extremes of temperature, productivity, or salinity in overlying surface waters. These parameters delimit a cold PolarSubpolar water mass and an impoverished, saline Southern Sargasso Central water mass for the late Recent. Anticipated pole-to-equator diversity and dominance gradients in the open ocean are virtually eliminated by the stronger trends of the vigorous subtropical North Atlantic gyre.
TL;DR: In this article, the results of O18 measurements on the pelagic species Globigerina pachyderma from a composite core show that the δO18 value has not changed since the latter part of the last glacial period.
Abstract: O18/O16 data on a depth profile of water samples from the Arctic Ocean reveal that near surface water is depleted in O18 by about 4‰, but water at depths greater than 350 meters reaches near normal open ocean water composition. The O18 profile very closely follows the salinity profile, with δO18 changing by about 0.8‰ per 1‰ salinity change. The results of δO18 measurements on the pelagic species Globigerina pachyderma from a composite core show that the δO18 value has not changed since the latter part of the last glacial period. This constancy we take to indicate that the temperature and the δO18 value of the water in which these foraminifera grew have not changed significantly since that time. Such a conclusion seems to imply that the present ice coverage in the Arctic Ocean has remained unchanged during the last 25,000 years. However, the δO18 value of benthonic foraminifera shows a shift of 1.2‰ between the end of the last glacial period and the present warm period. This shift is consistent with the idea that the deep water mass of the Arctic Ocean is formed outside the Arctic basin. The information on the δO18 value of the benthonic foraminifera from the top of the core was used in conjunction with the data on δO18 and temperature of the bottom water to establish the constant in the empirical equation relating δO18 values to temperature for the preparation procedure used in our laboratory. Based on this calibration, the data confirm A. W. H. Be's contention (personal communication, 1960) that G. pachyderma incorporates about one-half of its CaCO3 below 300 meters.
TL;DR: In this article, the authors described and illustrated the Late Cretaceous formations exposed along the south coast of Bornholm Island, Denmark, which contain well preserved assemblages of planktonic foraminifera.
Abstract: Late Cretaceous formations exposed along the south coast of Bornholm Island, Denmark, contain well preserved assemblages of planktonic foraminifera, which are described and illustrated. Two taxa, Whiteinella baltica and Hedbergella bornholmensis, are described as new. The oldest assemblage, Middle to early Upper Cenomanian in age, is essentially monospecific and indicative of a restricted pelagic environment. The overlying Lower Senonian faunules are diverse, contain large populations which are associated with other pelagic microfossils, and provide a more typical example of Boreal planktonic foraminiferal associations. Taxonomically the assemblages are largely composed of species of Hedbergella, Whiteinella, Archaeoglobigerina, Globigerinelloides, and Heterohelix and double-keeled species of Globotruncana, particularly G. marginata. These species are widely distributed in space and time. Thus Bornholm assemblages have a cosmopolitan aspect, which can be identified in microfaunas from the Western Interior of North America and Alaska. Because of the lower diversity, lack of restricted stratigraphic markers, Lower Senonian correlations between Bornholm, and probably Boreal pelagic microfaunas generally, coeval Tethyan assemblages are less precise than within the Tethys.
TL;DR: Foraminiferal shells resemble strings of hollow spheres of increasing diameter as discussed by the authors, which are coiled in a plane or on the surface of a cone and are defined as "normalform" shells.
Abstract: Most planktonic foraminiferal shells resemble strings of hollow spheres of increasing diameter. The strings are coiled in a plane or on the surface of a cone. Shells of this type are defined as "normalform." Of all the chambers making up such a string, generally the last one only may be smaller than or equal to the previous one. If a foraminifer builds such a chamber, it leaves the normalform stage and enters the "kummerform" stage (German kummerlich = measly). Attainment of the kummerform stage probably indicates environmental stress, notably lack of food. In many samples of calcareous deep-sea sediment, a large proportion of the planktonic Foraminifera are kummerforms. This contrasts with the living populations in the upper water column where kummerforms are rare. The enrichment of deep-sea sediment with kummerform Foraminifera may be caused by (1) a greater propensity for living kummerforms, than for normalforms, to deliver an empty shell and (2) selective destruction of normalforms on the ocean floor. There is evidence that both mechanisms may be important, depending on the oceanic environment in the upper water and on the ocean floor. Vigorous oceanic circulation may increase the proportion of kummerforms. Changes in the stability of oceanic environments thus may be recorded in the amount of kummerform Foraminifera in older deep-sea deposits. End_of_Article - Last_Page 706------------
TL;DR: In this paper, the association of living foraminifera with algae from the littoral zone, south Cardigan Bay, Wales, was investigated and the results showed that the association is not limited to a single species.
Abstract: (1969). The association of living foraminifera with algae from the littoral zone, south Cardigan Bay, Wales. Journal of Natural History: Vol. 3, No. 4, pp. 517-542.
TL;DR: This paper examined 350 samples from seven deep-sea cores raised in the Arctic Ocean Basin and found that faunal variations coincide with changes in sediment characteristics suggesting that regional climatic and hydrologic oscillations caused these alterations.
01 Aug 1969
TL;DR: In this article, a marked degree of similarity exists between the benthonic foraminiferal faunas of the Mediterranean and Caribbean regions from the Paleocene-Early Miocene.
Abstract: : A marked degree of similarity exists between the benthonic foraminiferal faunas of the Mediterranean and Caribbean regions from the Paleocene-Early Miocene. The stratigraphic ranges and geographic distribution of several groups of benthonic foraminifera are discussed. (Author)
01 Aug 1969
TL;DR: Foraminiferal assemblages obtained from five sites are mostly dominated by Elphidium clavatum and indicate middle Pleistocene interglacial conditions; in all forty-five species of foraminifera are recorded as mentioned in this paper.
Abstract: Summary Marine clay appearing to crop out between the Chalk and a boulder clay resembling the Purple Till of Holderness has been sampled by gravity coring on the flanks of the Inner Silver Pit between 53° 24·8′ to 53° 30·2′ N and 0° 40·8′ to 0° 41·8′ E. Foraminiferal assemblages obtained from five sites are mostly dominated by Elphidium clavatum and indicate middle Pleistocene interglacial conditions; in all forty-five species of foraminifera are recorded. Pollen indicating zones IIIb and IV of the temperate Hoxnian stage is present in the same
Journal Article•
TL;DR: Planktonic foraminifera occur sporadically throughout 395 feet of the Cannonball Formation at Garrison Dam, N. Dakota as mentioned in this paper, and are characteristic of the Globigerina edita Zone of Hillebrandt, 1965 (=Globorotalia pseudobulloides Zone of Bolli, 1966) and is considered diagnostic of the lower parts of the Danian stage.
Abstract: Planktonic foraminifera occur sporadically throughout 395 feet of the Cannonball Formation at Garrison Dam, N. Dak. The assemblage (7 species, none new) is characteristic of the Globigerina edita Zone of Hillebrandt, 1965 (=Globorotalia pseudobulloides Zone of Bolli, 1966) and is considered diagnostic of the lower parts of the Danian stage (below the Globorotalia trinidadensis Zone). This precise correlation of the Cannonball indicates a similar age for equivalent nonmarine formations in Montana, Wyoming, and the Dakotas (Ludlow, Tullock). The Ludlow in North and South Dakota has been dated as Paleocene on plant, spore, and pollen evidence. The Tullock in Wyoming contains Paleocene plants. Recently the Tullock in eastern Montana has yielded Paleocene mammals of the Puercan stage.
TL;DR: Populations of benthonic Foraminifera in the James River estuary, Chesapeake Bay region, comprise seventeen species; two species constitute 90% of the fauna as discussed by the authors.
01 Jan 1969
TL;DR: In this paper, the authors present a taxonomy of Foraminifera in the Pierre Shale and its subdivisions, including stratigraphic and areal distribution, along the Grand River.
Abstract: __________________________________________ Introduction. ______________________________________ Acknowledgments. __ ____________________________ Field methods._________________________________ Lithostratigraphy. __________________________________ Earlier investigations.___________________________ Lithology of the Pierre Shale_____________________ Virgin Creek Member of the Pierre Shale._____ Mobridge Member of the Pierre Shale.________ Elk Butte Member of the Pierre Shale_______ Type sections of the members._______________ General discussion of the lithologic subdivisionsDistinctive features of the upper part of the Pierre Shale._____________________________ Methods of correlation._________________________ Composite stratigraphic sequences ________________ Stratigraphic sequence along the Moreau River. Stratigraphic sequence along the Grand River. _ Relationship of the sequences______________ Biostratigraphy.. _ __________________________________ Regional correlation ___________________________ Composition of the fauna._______________________ Page 1 1 2 3 3 3 3 4 4 4 5 5 6 7 8 8 9 11 15 15 19 Biostratigraphy Continued Paleoecology _ ___________________________ Paleogeographic setting_______________ Foraminiferal biofacies________________ Lower arenaceous biofacies_______ Upper arenaceous biofacies__ ___. Calcareous biofacies _____ _______ Stratigraphic and areal distribution. Faunal details and origin._________ Environmental interpretations.___-_____-__-___. Biologic information._____________________ Lithologic information.__________________ Recent analogs._________.__----____-__--. Conclusions.________-_---__-------__-_--. Paleontology._____________---__----_____-___. Laboratory methods._____________________ Macrof ossils. ________________ __________ Ostracodes_ ______________________________ Classification and taxonomy of Foraminifera. 19 19 21 21 22 22 23 23
01 Jan 1969
TL;DR: A fauna of organisms as minute as the Foraminifera, which otherwise might be restricted to microenvironments, can become cosmopolitan when carried to different areas where they can survive and reproduce if the environmental conditions are favorable.
Abstract: The marine grass, Thalassia testudinum Konig, is distributed throughout the West Indian region and the island of Bermuda. Its distribution is controlled by temperature, salinity, turbulence and depth. It supplies a substrate for many organisms including benthonic Foraminifera. Sixty-six benthonic foraminiferal species were found living on Thalassia in a relatively small area in the Florida Keys. Of these only 18 species were abundant and these same species were noted living on the marine grass wherever it was examined throughout the area of its distribution. The distribution and abundance of these Foraminifera are controlled by competition with other organisms living in the same environment as well as by interspecific competition. Tropical and subtropical shallow water benthonic foraminiferal faunas are essentially composed of the same species throughout the West Indian region. The Thalassia blades provide a means of dispersal for the benthonic species. When the tops of the blades die, or when complete plants are broken off by storms or strong wave action, they float and can be transported great distances by currents. The organisms living on the grass blades are thus carried to different areas where they can survive and reproduce if the environmental conditions are favorable. Even sediment-preferring species can be transported by this means, for juvenile specimens, and even some adult specimens, are usually of such low specific gravity that they can be thrown into suspension by storm waves and may settle onto blades of Thalassia. In this manner a fauna of organisms as minute as the Foraminifera, which otherwise might be restricted to microenvironments, can become cosmopolitan.
TL;DR: In this paper, the assemblage of arenaceous forms was described, and the affinity with Australian faunas was found in the lower Cretaceous of the Australian Faunas.
Abstract: Systematic descriptions, assemblage of arenaceous forms, lower Cretaceous, affinity with Australian faunas
01 Jan 1969
TL;DR: In this article, foraminiferal faunas in 89 sediment samples from the barrier reef and lagoon of British Honduras showed that the largest living and total foraminifera populations are on the leeward side of mangrove and coral-sand cays in the reef tract, and in the lagoon near the mouths of rivers.
Abstract: Analysis of foraminiferal faunas in 89 sediment samples from the barrier reef and lagoon of British Honduras showed that the largest living and total foraminiferal populations are on the leeward side of mangrove and coral-sand cays in the reef tract, and in the lagoon near the mouths of rivers. The living Foraminifera were divided into the barrier-reef-tract and lagoon faunas, reflecting the two major environments of the area. The reef-tract fauna was divided further into the main-reef, reef-margin, and reef-channel assemblages. Temperature and salinity measurements of 41 bottom-water samples indicated a decrease in temperature and an increase in salinity from the mainland toward the barrier reef.
Journal Article•