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Wyszukujesz frazę "Cenomanian–Turonian Anoxic Event" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
A marker band folgen stratigraphy for the Cenomanian Chalk of England and its extension to northen Germany and France
Autorzy:
Jeans, Christopher Vincent
Powiązania:
https://bibliotekanauki.pl/articles/27323962.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
Cretaceous
cenomanian chalk
folge stratigraphy
marker bands
England
Northern Germany
Northwest France
Cenomanian–Turonian Anoxic Event
kreda
stratygrafia
Anglia
Niemcy Północne
północno-zachodnia Francja
cenoman
turon
Opis:
A novel stratigraphical scheme within the Folge Concept is described for the Cenomanian Chalk of England that is particularly suitable for investigating the regional changes in the lithofacies, diagenesis, geochemistry, and mineralogy of the sediments of the Chalk Sea leading up to the Cenomanian–Turonian Oceanic Anoxic Event. It is based on “isochronous” marker bands defined largely by calcitic macrofossil assemblages, and it avoids problems caused by the poor or non-preservation of ammonite assemblages and lateral changes in chalk lithofacies. Eight folgen are based on one, two, or more marker bands. Their sequences, lithologies and calcitic macrofossil assemblages are described from 33 exposures in the Northern Chalk Province of England. The folgen are named, in ascending order, the Belchford, Stenigot, Dalby, Bigby, Candlesby, Nettleton, Louth and Flixton, after villages in Lincolnshire and Yorkshire, England. The folgen are traced throughout the Transitional and Southern Chalk provinces of England. They are present in the Cenomanian chalk of northern Germany and northwest France. Regionally, an individual folge may display considerable vertical and lateral variation in general lithology and lithofacies whilst still maintaining their defining marker bands. The possibility of further refinement to the scheme is discussed.
Źródło:
Acta Geologica Polonica; 2023, 73, 2; 135--180
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Redox conditions, glacio-eustasy, and the status of the Cenomanian-Turonian Anoxic Event: new evidence from the Upper Cretaceous Chalk of England
Autorzy:
Jeans, Christopher V.
Wray, David S.
Williams, C. Terry
Bland, David J.
Wood, Christopher J.
Powiązania:
https://bibliotekanauki.pl/articles/1835600.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Cretaceous
Cenomanian–Turonian Anoxic Event
eustatic lithocycles
glacial associations
redox conditions
cerium anomalies
carbon isotopes
NW Europe
Japan
kreda
cenoman
turon
asocjacje
redoks
izotopy węgla
północno-zachodnia Europa
Japonia
Opis:
The nature of the Cenomanian–Turonian Oceanic Anoxic Event (CTOAE) and its δ13 C Excursion is considered in the light of (1) the stratigraphical framework in which the CTOAE developed in the European shelf seas, (2) conclusions that can be drawn from new detailed investigations of the Chalk succession at three locations in England, at Melton Ross and Flixton in the Northern Province where organic-rich ‘black bands’ are present, and at Dover in the Southern Province (part of the Anglo-Paris Basin) where they are absent, and (3) how these conclusion fit in with the present understanding of the CTOAE. The application of the cerium anomaly method (German and Elderfield 1990) at Dover, Melton Ross and Flixton has allowed the varying palaeoredox conditions in the Chalk Sea and its sediments to be related to the acid insoluble residues, organic carbon, δ18O (calcite), δ13C (calcite), δ13C (organic matter), Fe 2+ and Mn2+ (calcite), and P/TiO2 (acid insoluble residue). This has provided evidence that the initial stages of the δ13C Excursion in England were related to (1) a drop of sea level estimated at between 45 and 85 metres, (2) influxes of terrestrial silicate and organic detritus from adjacent continental sources and the reworking of exposed marine sediments, and (3) the presence of three cold water phases (named the Wood, Jefferies and Black) associated with the appearance of the cold-water pulse fauna during the Plenus Cold Event. Conditions in the water column and in the chalk sediment were different in the two areas. In the Northern Province, cerium-enriched waters and anoxic conditions were widespread; the δ13C pattern reflects the interplay between the development of anoxia in the water column and the preservation of terrestrial and marine organic matter in the black bands; here the CTOAE was short-lived (~0.25 Ma) lasting only the length of the Upper Cenomanian Metoicoceras geslinianum Zone. In the Southern Province, water conditions were oxic and the δ13C Excursion lasted to the top of the Lower Turonian Watinoceras devonense Zone, much longer (~1.05 Ma) than in the Northern Province. These differences are discussed with respect to (1) the Cenomanian–Turonian Anoxic Event (CTAE) hypothesis when the ocean-continent-atmosphere systems were linked, (2) limitations of chemostratigraphic global correlation, and (3) the Cenomanian-Turonian Anoxic Event Recovery (CTOAER), a new term to define the varying lengths of time it took different oceans and seas to recover once the linked ocean-continent-atmosphere system was over. The possibility is considered that glacio-eustasy (the glacial control hypothesis of Jeans et al. 1991) with the waxing and waning of polar ice sheets, in association with the degassing of large igneous provinces, may have set the scene for the development of the Cenomanian-Turonian Anoxic Event (CTAE).
Źródło:
Acta Geologica Polonica; 2021, 71, 2; 103-152
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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