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Titolo:
Early Cretaceous calcareous nannofossils from high latitudes: implicationsfor palaeobiogeography and palaeoclimate
Autore:
Mutterlose, J; Kessels, K;
Indirizzi:
Ruhr Univ Bochum, Inst Geol Mineral & Geophys, D-44801 Bochum, Germany Ruhr Univ Bochum Bochum Germany D-44801 Geophys, D-44801 Bochum, Germany
Titolo Testata:
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
fascicolo: 3-4, volume: 160, anno: 2000,
pagine: 347 - 372
SICI:
0031-0182(20000715)160:3-4<347:ECCNFH>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
WESTERN-EUROPE; BARENTS SEA; PALEOCEANOGRAPHY; BIOSTRATIGRAPHY; CARBONATES; PRESERVATION; CLIMATES; ENGLAND; PACIFIC; EVENTS;
Keywords:
C. salebrosum; calcareous nannofossils; Early Cretaceous; high latitudes; palaeobiogeography; palaeoclimate;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
71
Recensione:
Indirizzi per estratti:
Indirizzo: Mutterlose, J Ruhr Univ Bochum, Inst Geol Mineral & Geophys, Univ Str 150,D-44801 Bochum, Germany Ruhr Univ Bochum Univ Str 150 Bochum Germany D-44801 ermany
Citazione:
J. Mutterlose e K. Kessels, "Early Cretaceous calcareous nannofossils from high latitudes: implicationsfor palaeobiogeography and palaeoclimate", PALAEOGEO P, 160(3-4), 2000, pp. 347-372

Abstract

In order to better understand the palaeoceanography and palaeoclimate of the Early Cretaceous, nannofossil data have been obtained from high-latitudinal sites from offshore mid-Norway and from the Barents Sea. No consistent nannofossil data are yet available for Early Cretaceous high latitudes, which should more clearly reflect possible palaeoclimatic changes, as recordedin fluctuations of diversity and abundance. Existing data from France, Italy, Romania, Poland and NW Europe (Germany, North Sea, England) have been complemented by material from higher latitudes. In order to record the Arctic-Boreal nannofossil assemblages, 400 samples from the Norwegian Shelf and the Barents Sea have been analysed. Sixty samples, covering the Berriasian-Barremian interval, yielded calcareous nannofossils. These are derived fromcores between 63 and 73 degrees N of present-day latitudes. The nannofossil assemblages recorded are generally of a low diversity and characterized by abundant Watznaueria barnesae and Crucibiscutum salebrosum, whereas Biscutum constans is less common. C. salebrosum, rare or absent at low latitudes, is extremely common in the Norwegian samples. It shows a bipolar distribution especially during Valanginian-Hauterivian times. In the early Valanginian, a distinctive latitudinal gradient in the abundance of C. salebrosum, impoverished in low latitudes add abundant in high latitudes, possibly reflects latitudinal differences in temperature. Restricted palaeoceanographic settings, caused by a sea-level lowstand, may have amplified these thermal gradients. Palaeoclimatically this implies the existence of climatic belts throughout parts of the Early Cretaceous (early Valanginian, Hauterivian), resulting from considerable temperature gradients from north to south. The palaeobiogeographic patterns discussed resulted in the formation of distinctive latitudinally bound nannofossil zones, which, to a certain extent, aresimilar to those of modern oceans. The palaeobiogeographic patterns described support the idea of an ice-house phase for the early Valanginian and disagree with the suggestion of a globally warm equable climate during that time. (C) 2000 Elsevier Science B.V. All rights reserved.

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Documento generato il 11/07/20 alle ore 07:46:10