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Projekt Druckansicht

Sea-water temperatures of the early Cretaceous derived from stable isotopes of belemnites and TEX86 of organic-rich sediments

Fachliche Zuordnung Mineralogie, Petrologie und Geochemie
Förderung Förderung von 2006 bis 2011
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 20783769
 
Erstellungsjahr 2011

Zusammenfassung der Projektergebnisse

The major findings can be summarized as follows: 1) The Valanginian - Aptian of the Boreal Realm is characterized by significant temperature variations which have been documented by using the palaeo-thermometry of the stable oxygen isotope ratios. The Valanginian and Hauterivian were generally cool, warmest phases have been demonstrated for the early Barremian. The "Aulacoteuthis warm pulse" records the highest T°C throughout the entire Valanginian – Aptian in the Boreal Realm. 2) Both TEX 86 and delta 18 O Bel proxy data indicate very warm water temperatures for the Barremian with, however, a constant off-set of 4°C between both data sets. These findings have been interpreted to indicate a subsurface dwelling of belemnites in water depth of perhaps 100m, explaining the relative “cold” delta 18 O Bel values. 3) Positive delta 13 C excursions, well known from the Tethys, have been documented for the Boreal Realm both for the mid Valanginian and the early Aptian. 4) The Mg incorporation in belemnite rostra suggests a biological control for "Acroteuthis" spp. and "Hibolithes jaculoides", perhaps reflecting different food sources. 5) Modern cephalopds originated 35 my before the Cretaceous/Paleogene extinction in the North Pacific due to faunal isolation.

Projektbezogene Publikationen (Auswahl)

 
 

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