Skip to Main content Skip to Navigation
Theses

Enregistrement à haute résolution des modifications environnementales inscrites dans un cadre téphrochronologique : le bassin du Western Interior au passage Cénomanien-Turonien

Abstract : During the Cenomanian-Turonian boundary interval, over 2Ma, five altered volcanic-ash beds, which are isochronous time-line, have been correlated over tens of thousands of square kilometres through the US Western Interior Basin from Arizona to Kansas and from Texas up to South Dakota while passing by the Pueblo type section (Colorado). These instantaneous events constitute independent chronostratigraphic marker-beds enabling the robustness of lithologica, biological (planktic and benthic foraminefera, calcareous nannofossils) or geochemical (S13C, S18C) records to be tested as tool for high resolution correlations. As suggested by our scheme, differences obseved between supposed continuous sections could be related, with some hiatuses in the sedimentary record. If correct, one hiatus may have been as long as 800 Kyrs. The onset and most of the fine-scale features of carbon-isotope excursion identified at pueblo are recognised over long distances even in the more coastal sections where bed by bed correlations become more difficult. Thus, this tool appears extremely robust if the hiatuses are precisely constrained. Some bioevents as the benthic zone or the Heterohelix event are synchronous at the scale of the Western Interior Basin and they could be used as global stratigraphic tools; they also coincide with events recorded by S13Ccarb (respectively phase of oxygenation and second rise of the anoxia). On the basis of this high resolution scheme, we show that the filament event, the last occurences of R. cushmani as well as the first occurence of H. helvetica are strongly diachronous at the basin scale. Thus the W. archaeocretacea Partial Range Zone, in which is the Cenomanian-Turonian boundary, has a variable duration. If it is reduced at almost nothing at Pueblo (<50 Ka), it reaches at least 350 Ka on the stable eastern platform in Kansas.
Document type :
Theses
Complete list of metadatas

https://pastel.archives-ouvertes.fr/pastel-00001829
Contributor : Ecole Mines Paristech <>
Submitted on : Thursday, August 5, 2010 - 5:48:44 PM
Last modification on : Wednesday, October 14, 2020 - 3:57:40 AM
Long-term archiving on: : Friday, September 10, 2010 - 4:17:57 PM

Identifiers

  • HAL Id : pastel-00001829, version 1

Citation

Delphine Desmares. Enregistrement à haute résolution des modifications environnementales inscrites dans un cadre téphrochronologique : le bassin du Western Interior au passage Cénomanien-Turonien. Sciences de la Terre. Université Louis Pasteur - Strasbourg I, 2005. Français. ⟨NNT : 2005STR1GE08⟩. ⟨pastel-00001829⟩

Share

Metrics

Record views

441

Files downloads

179