نتایج جستجو برای: planktonic and benthic foraminifera
تعداد نتایج: 16831487 فیلتر نتایج به سال:
Today, Antarctica exhibits some of the harshest environmental conditions for life on Earth. During the last glacial period, Antarctic terrestrial and marine life was challenged by even more extreme environmental conditions. During the present interglacial period, polar life in the Southern Ocean is sustained mainly by large-scale primary production. We argue that during the last glacial period,...
A detailed oxygen isotope time-scale based on planktonic foraminifera Globigerinoides sacculifer at site MD012380 in the Banda Sea was established for the past 820 kyrs by correlating the record to the astronomically tuned benthic oxygen isotope chronology of MD972143. Ages for marine isotope stratigraphic (MIS) events from 2.0 back to 21.1 were designated for this western tropical Pacific reco...
[1] Radiocarbon differences between benthic and planktonic foraminifera (B-P ages) and radiocarbon projection ages are both used to determine changes of the past ocean circulation rate. A global 3-D ocean circulation model with a constant modern ocean circulation is used to study which method is less influenced by atmospheric DC variations. Three factors cause uncertainties: first, the long equ...
Latitudinal gradients of biodiversity and macroevolutionary dynamics are prominent yet poorly understood. We derive a model that quantifies the role of kinetic energy in generating biodiversity. The model predicts that rates of genetic divergence and speciation are both governed by metabolic rate and therefore show the same exponential temperature dependence (activation energy of approximately ...
Holocene paleohydrology reconstruction is derived combining planktonic and benthic stable oxygen and carbon isotopes, sea surface temperatures (SSTs) and oxygen isotope composition of seawater (δOw) from a high sedimentation core collected in the South Adriatic Sea (SAS). Core chronology is based on 10 AMS 14C measures on planktonic foraminifera and tephra layers. Results reveal two contrasted ...
Thirteen species of planktonic foraminifera collected with vertically stratified zooplankton tows in the slope water, Gulf Stream cold core ring, and northern Sargasso Sea show significant differences in their vertical distributions in the upper 200 meters of these different hydrographic regimes. Gulf Stream cold core rings may be responsible for a southern displacement of the faunal boundary a...
Dredge samples of Upper Jurassic-lowest Cretaceous limestones were recovered from western Galicia margin. Limestones include benthic and/or planktonic assemblages, which were deposited in environments ranging from inner to outer shelf or upper slope.
The Maastrichtian–Eocene sediments (mainly shales and limestones) penetrated by the Itori borehole Ilaro boreholes in Dahomey Basin were investigated for foraminiferal biostratigraphy palaeoecological interpretation. These Araromi, Ewekoro, Oshosun formations at varying depths. Selected shale subjected to analysis many planktonic benthic species of foraminifera (agglutinated calcareous) recover...
Abstract. Muricate planktonic foraminifera comprise an extinct clade that was diverse and abundant in the Paleogene oceans are widely used palaeoclimate research as geochemical proxy carriers for upper oceans. Their characteristic wall texture has surface projections called “muricae” formed by upward deflection mounding of successive layers test wall. The group is generally considered to have l...
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