|High-resolution stratigraphy of the Cenomanian-Turonian boundary interval at Pueblo (USA) and wadi Bahloul (Tunisia) stable isotope and bio-events correlation|Caron, M.; Dall'Agnolo, S.; Accarie, H.; Barrera, E.; Kauffman, E.G.; Amedro, F.; Robaszynski, F. (2006). High-resolution stratigraphy of the Cenomanian-Turonian boundary interval at Pueblo (USA) and wadi Bahloul (Tunisia) stable isotope and bio-events correlation. Géobios 39(2): 171-200. dx.doi.org/10.1016/j.geobios.2004.11.004
In: Géobios. Association Européenne de Paléontologie: Lyon. ISSN 0016-6995, more
Cenomanian-Turonian; stable isotopes; ammonites; planktic foraminifera;bioevents; biostratigraphy
|Authors|| || Top |
- Caron, M.
- Dall'Agnolo, S.
- Accarie, H.
- Barrera, E.
- Kauffman, E.G.
- Amedro, F.
- Robaszynski, F., more
A high-resolution stratigraphy has been developed for the interval encompassing the Cenomanian-Turonian boundary (CTBI), by means of several lithological, biological and geochemical events. This work entails the study of two sections selected on the base of the completeness of their sedimentary record and their contrasting paleogeographical setting: (1) The Rock Canyon Anticline section west of Pueblo, Colorado, (US Western Interior Basin), which is the Global Boundary Stratotype Section and Point (GSSP) candidate for the base of the Turonian stage, as well as the reference section for the ammonite biostratigraphy of the CTBI; and (2) The wadi Bahloul section in Central Tunisia which is the best and complete section spanning this time interval in the southern Tethyan Margin. These sections record similar biogeochemical events that can be correlated over a great distance.
Several important biological and geochemical events determined in these sections relative to the ammonite zonation of the CTBI are listed below in chronological order from old to young: 1. FO (first occurrence) of Sciponoceras gracile-Metoicoceras geslinianum ammonite Assemblage-Zone, 2. delta C-13 peak 1, 3. LO (last occurrence) of Rotalipora cushmani, 4. "Heterohelic shift", 5. FO of the ammonites Pseudaspidoceras pseudonodosoides and Neocardioceras juddii, 6. delta C-13 peak II, 7. delta C-13 peak III, 8. LO of Cenomanian ammonites (Ps. pseudonodosoides and N. juddii), 9. LO of Anaticinella, 10. FO of Turonian ammonites (Watinoceras devonense, base of the Turonian stage), 11. "filament event", 12. FO of Pseudaspidoceras flexuosum, 13. FO of the Tethyan Helvetoglobotruncana helvetica, 14. FO of Mammites nodosoides, 15. FO of the Western Interior H. helvetica.
In the two sections, the Cenomanian-Turonian (C/T) boundary, as defined by the ammonite biostratigraphy, is placed within an interval about 50 cm thick. This interval is termed here as the C/T boundary "precision interval". The delta C-13 peak III slightly precedes the precision interval. The genus Anaticinella planktic foraminifer disappears in the middle part of this interval. The "filament event" occurs just above it and is coeval with the first occurrence of Turonian ammonites. These events are useful for placing the C/T boundary precision interval in absence of ammonite markers.