scholarly journals Age determinations of Neogene sediments from the English Channel and Western Approaches

1986 ◽  
Vol 5 (1) ◽  
pp. 5-6
Author(s):  
D. Graham Jenkins ◽  
Erlend Martini
Keyword(s):  
Middle Miocene ◽  
Planktonic Foraminifera ◽  
English Channel ◽  
Calcareous Nannoplankton ◽  
Lower Miocene ◽  
Published Evidence ◽  
Neogene Sediments ◽  
Age Range ◽  
Age Determinations

Abstract. Original published evidence indicated an age range of early Lower Miocene to early Middle Miocene for Globigerina silt samples from the English Channel and the Western Approaches. Suggested younger ages for these samples are refuted on the basis of planktonic foraminifera and calcareous nannoplankton.

scholarly journals An Early Miocene biserial foraminiferal event in the Transylvanian Basin (Romania)

2010 ◽  
Vol 61 (3) ◽  
pp. 227-234 ◽  
Author(s):  
Claudia Beldean ◽  
Sorin Filipescu ◽  
Ramona Bălc
Keyword(s):  
Middle Miocene ◽  
Planktonic Foraminifera ◽  
Early Miocene ◽  
High Abundance ◽  
Calcareous Nannoplankton ◽  
Lower Miocene ◽  
Precise Identification ◽  
Pacific Area

An Early Miocene biserial foraminiferal event in the Transylvanian Basin (Romania)Investigations of the Lower Miocene of the Transylvanian Basin reveal particularly high abundances (> 90 % of total foraminifera) of small sized biserial foraminifera (Bolivina/Streptochilus). This biotic event has not been noticed in the Transylvanian Basin so far probably owing to the facies misinterpretation and the small size of the specimens. SEM investigations allow more precise identification of biserial planktonic taxa and more accurate taxonomic interpretations. The high abundance ofBolivina/Streptochilusassemblages provide evidence for paleogeographic connections to the Indo-Pacific area and support new paleoenvironmental interpretations at the transition from the Early to Middle Miocene in relation to the paleoceanographic events. Both planktonic foraminifera and calcareous nannoplankton suggest a late Burdigalian age. A newBolivina/StreptochilusAbundance Biozone is proposed just below the Early/Middle Miocene boundary.

Calcareous nannoplankton and the age of the Globigerina silts of the western approaches of the English Channel

1974 ◽  
Vol 111 (4) ◽  
pp. 303-306 ◽  
Author(s):  
E. Martini
Keyword(s):  
Atlantic Ocean ◽  
North Sea ◽  
English Channel ◽  
Calcareous Nannoplankton ◽  
Northern Germany ◽  
Lower Miocene ◽  
The North ◽  
The North Sea

SummaryCalcareous nannoplankton from the Globigerina silts of the western approaches of the English Channel indicate the presence of standard nannoplankton zones NN2, NN 4 and NN 5, part of which can be correlated with Neogene beds in Belgium and Northern Germany. The calcareous nannoplankton support the possibility of a connexion between the North Sea Basin and the Atlantic Ocean through the English Channel during part of the Lower Miocene.

Biostratigraphic correlation of Miocene drillings in the Vienna Basin (Austria) - Integrated Neogene stratigraphy of the largest onshore petroleum province in Central Europe (Vienna Basin, Austria)

2020 ◽  
Author(s):  
Matthias Kranner ◽  
Mathias Harzhauser ◽  
Oleg Mandic ◽  
Werner E. Piller ◽  
Stjepan Ćorić ◽  
...  
Keyword(s):  
Cross Section ◽  
Middle Miocene ◽  
Fault System ◽  
3D Seismic ◽  
Calcareous Nannoplankton ◽  
Vienna Basin ◽  
Pull Apart Basin ◽  
Complex Fault ◽  
Neogene Sediments ◽  
Oil Company

<p>Numerous boreholes of the OMV oil company penetrate the northern Vienna Basin (VB) and several detailed analyses have been conducted on these drilling for years. Despite the effort of decades, the distribution and correlation of Neogene sediments throughout the basin remained ambiguous, due to the complex fault system of the VB. To resolve remaining issues of the Neogene deposits of the area OMV initiated detailed integrative stratigraphic analyses, combining biostratigraphical, lithological, modern 3D seismic- and geophysical data.</p><p>Paleontological analysis with main focus on micropaleontology, especially foraminifers, of 46 wells (more than 650 samples) of the northern Vienna Basin have been conducted and help to create a well resolved stratigraphic north – south cross-section of the Neogene units. Of particular interest were lower and middle Miocene (Ottnangian, Karpatian, Badenian and Sarmatian) units. Hardly known and described were the patchy lower Badenian deposits and the much more complex, than previously expected, middle Badenian units. Foraminiferal analysis revealed about 50.000 specimens belonging to 228 species and an allocation to local ecozones, biostratigraphic zonations and ecological reconstructions were established.</p><p>Additionally, 50 samples have been analyzed for calcareous nannoplankton which showed extreme reworking throughout all successions.</p><p>Some samples displayed the underlying Mesozoic limestones and cutting samples of one well brought insights into the Cenozoic underling Rhenodanubian Flysch units of the Vienna Basin This huge and stratigraphic long ranging set of data did not just reveal major sedimentation gaps during the formation of the modern pull-apart basin, but also provided the opportunity to create a framework for a modern sequence stratigraphy re-assessment of the Vienna Basin.</p><p>Furthermore, a formalization of widely used formations in literature will be established in later steps of this project.</p><p>This project was financed by the OMV-AG.</p>

MOSAIC EVOLUTION IN THE MIDDLE MIOCENE PLANKTONIC FORAMINIFERA GLOBOROTALIA FOHSI LINEAGE

2016 ◽  
Author(s):  
Weimin Si ◽  
◽  
William Berggren ◽  
Marie-Pierre Aubry
Keyword(s):  
Middle Miocene ◽  
Planktonic Foraminifera ◽  
Mosaic Evolution

scholarly journals Screening for Melanoma and Options For-Its Evaluation

1994 ◽  
Vol 1 (1) ◽  
pp. 22-38 ◽  
Author(s):  
J M Elwood
Keyword(s):  
General Population ◽  
Large Scale ◽  
Randomised Trial ◽  
Risk Groups ◽  
Population Screening ◽  
Data Systems ◽  
Case Control Studies ◽  
Published Evidence ◽  
High Incidence ◽  
Age Range

A review of the published evidence presented here argues that screening for melanoma is recommended and practised at present, but with wide diversity of opinions about its value; there is evidence that screening has considerable potential for benefit, but the evidence of actual benefit is limited; and there are substantial costs and potential hazards from screening. On this basis the evaluation of screening procedures for melanoma is important, and options for this are discussed. The ideal study design to assess the efficacy of melanoma screening in reducing mortality is a large scale randomised trial. This may need a well coordinated proposal involving several centres in one or more countries, and the cost would be substantial. Without such a trial, however, it is most likely that increasing resources will be put into poorly designed screening programmes of unknown value. The simplest and strongest designs use individual randomisation, but group randomisation designs may have practical advantages, though they require a greater sample size. Designs based on general population screening, and on screening only high risk groups, are both considered. They answer different questions. In countries with high incidence the value of general population screening is probably the more critical. Not enough is known to specify the type and frequency of screening precisely; both screening by doctors and self screening require evaluation, and annual screening should probably be tested. The age range at risk will depend on the local incidence, but is likely to be quite wide — for example, 45–69, and both sexes need inclusion. Thus a suggested design for a moderate to high incidence area would be a trial, randomised by individual or group, assessing at least two annual rounds of both screening by doctor and self screening (ideally by a factorial design), for adults aged 45–69, with mortality over several years' follow up as the critical outcome. In an area with good data systems such a study could compare screening offered to some 260.000 subjects with 10 times that number of controls passively followed up, with 90% power to detect a one third reduction in mortality. A general assessment of costs over five years gave estimates of $8.3 million for the screening programme and $2.4 million for the evaluation. The much weaker designs, area based cohort studies using individual data or a simpler ecological comparison, and case-control studies, are also considered. If well designed with attention to their methodological limitations they may be valuable but are unlikely to be as definitive as a randomised trial.

scholarly journals Late Paleocene event chronology; unconformities, not diachrony

2000 ◽  
Vol 171 (3) ◽  
pp. 367-378 ◽  
Author(s):  
Marie-Pierre Aubry ◽  
Benjamin S. Cramer ◽  
Kenneth G. Miller ◽  
James D. Wright ◽  
Dennis V. Kent ◽  
...  
Keyword(s):  
Planktonic Foraminifera ◽  
Calcareous Nannoplankton ◽  
Lower Eocene ◽  
Late Paleocene ◽  
Relative Chronology ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Unequivocal Identification ◽  
Upper Paleocene ◽  
Reference Section

Abstract The chronology of the events associated with the late Paleocene thermal maximum (LPTM, Chron C24r) has been established through the construction of a composite reference section that involved chemomagnetobiostratigraphic correlations and assumed minimum diachrony of biostratigraphic events. On this basis, discrepancies between correlations in different sections were explained by inferred unconformities. However, diachrony between distant sections cannot be ruled out. We report here on two geographically close sections drilled onshore New Jersey that yield different records of chemomagnetobiostratigraphic correlations in the interval representing Chron C24r. Because of their proximity ( approximately 40 km apart), diachrony of biostratigraphic events between the two sections can be ruled out. In contrast, the marked lithologic disconformities in the sections explain well the different records of events. We thus conclude that the current relative chronology for Chron C24r is firmly based and that the upper Paleocene-lower Eocene stratigraphic record yields multiple unconformities, with Subzone NP9b rarely sampled. We examine the implications that undeciphered unconformities may have on the identification of proxies for paleoceanographic reconstruction, in particular with regard to the identification of the carbon isotope excursion (CIE) that reflects a dramatic latest Paleocene disturbance of the carbon cycle. We propose biostratigraphic means (short-lived calcareous nannoplankton and planktonic foraminifera taxa) that permit the unequivocal identification of the CIE not only in the oceanic realm but also in neritic settings.

Middle Miocene planktonic microfossils and lower bathyal foraminifera from offshore southern California

1986 ◽  
Vol 60 (2) ◽  
pp. 249-267
Author(s):  
Ted F. W. Bergen ◽  
Joanne Sblendorio-Levy ◽  
John T. Twining ◽  
Richard E. Casey
Keyword(s):  
New Species ◽  
New Taxa ◽  
Benthic Foraminifera ◽  
Southern California ◽  
Middle Miocene ◽  
Calcareous Nannofossils ◽  
Calcareous Nannofossil ◽  
New Subspecies ◽  
Submarine Ridge ◽  
Age Range

Lower bathyal sediments representing portions of the Luisian and Mohnian stages of Kleinpell (1938) occur on a submarine ridge near Tanner Bank, offshore southern California. The presence of abundant and well-preserved calcareous nannofossils, diatoms, silicoflagellates, radiolarians and foraminifera allows accurate correlations with the onshore type sections of these stages. In terms of the calcareous nannofossil zones, the age range is from the Sphenolithus heteromorphus Zone to the Discoaster kugleri Zone. Although abundant benthic foraminifera indicative of the Luisian and Mohnian are present, they are accompanied by species more characteristic of the Pliocene Repettian Stage of Natland (1952) and the Pliocene-Miocene “Delmontian” Stage of Kleinpell (1938). Many of these latter species live today at lower bathyal depths (below 2,000 m), others occur in lower bathyal sediments as old as Oligocene, but are absent in the onshore type sections of the Luisian and Mohnian stages in coastal California. We ascribe their absence in onshore sequences to deposition at middle bathyal depths. The known chronostratigraphic ranges of several species are extended and five new species and two new subspecies of benthic foraminifera are described.The following new taxa are described: Bolivina pelita n. sp., Cassidulinella inflata n. sp., Globocassidulina undulata n. sp., Cibicidoides mckannai miocenicus n. subsp., C. mckannai sigmosuturalis n. subsp., Pullenia fragilis n. sp., Parafissurina inornata n. sp.

scholarly journals Remarks on the Messinian evaporites of Zakynthos Island (Io- nian Sea, Eastern Mediterranean).

2016 ◽  
Vol 47 (1) ◽  
pp. 146 ◽  
Author(s):  
V. Karakitsios ◽  
M. Roveri ◽  
S. Lugli ◽  
V. Manzi ◽  
R. Gennari ◽  
...  
Keyword(s):  
Shallow Water ◽  
Eastern Mediterranean ◽  
Thickness Distribution ◽  
Planktonic Foraminifera ◽  
Water Environment ◽  
Foreland Basin ◽  
Seismic Profile ◽  
Depositional Environments ◽  
Borehole Data ◽  
Neogene Sediments

Detailed mapping of the Neogene deposits on Zakynthos Island shows that the Messinian primary evaporite basins, formed over Ionian basement, are delimited by the westernmost outcrop of the Triassic evaporitic diapirs, located west of the Kalamaki-Argasi Messinian gypsum unit. The post-Miocene external Ionian thrust is emplaced west of the Triassic diapirs. Planktonic foraminifera biostratigraphy indicates that primary evaporite accumulation took place probably during the first stage of the Messinian salinity crisis (5.96-5.60 Ma), in shallower parts of a foreland basin, formed over the Pre-Apulian and the Ionian zone basement. Establishment of these depositional environments, before the Ionian thrust emplacement, was probably due to the particularities of the foreland basin, which extended from the external Ionian to the internal Pre-Apulian zone. Field observations, borehole data and an onshore seismic profile show that the Neogene sediments over the Pre-Apulian  basement correspond to the foredeep through forebulge domain of the foreland basin, as it is documented from their spatial thickness distribution. In contrast, the Neogene sediments over the Ionian basement correspond to the wedge top of the foreland basin, which was less subsiding, as it is deduced by their reduced thickness. This lower subsidence rate was the result of the concurrent diapiric movements of the Ionian Triassic evaporites. In Agios Sostis area, located over Pre-Apulian basement, the Neogene sequence is intercalated by decametre-thick resedimented blocks consisting of shallow water selenite. To the southeast, this mass-wasting Messinian gypsum passes to mainly gypsum turbidite. In Kalamaki-Argasi area, located over Ionian basement, the shallow water environment led to the deposition of the observed primary gypsum. Erosion of the primary gypsum of both forebulge and wedge top supplied the foreland basin’s depocenter with gypsum turbidites.

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