Journal article

The global bio-events at the Cenomanian-Turonian transition in the reduced Bahloul Formation of Bou Ghanem (central Tunisia)

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    21.07.2009
Published in:
  • Cretaceous Research. - 2010, vol. 31, no. 1, p. 1-15
English In central Tunisia, the thickness of the Bahloul Formation varies generally between 20 to 40 m such as for example, respectively, at wadi Smara near Kalaat Senan and at wadi Bahloul near Maktar. The thickness is also of several tens metres at Koudiat el Azreg near Jerissa and at Tajerouine. In these sites where the thickness of the Bahloul Formation is dilated, in addition to five geochemical events (δ¹³C), nine bio-events were defined near the Cenomanian-Turonian transition, successively in ascending order: 1. LO Rotalipora cushmani, 2. Heterohelix bio-event, 3. FO Pseudaspidoceras pseudonodosoides, 4. LO P. pseudonodosoides, 5. LO Thalmanninella multiloculata, 6. “filaments” bio-event, Cenomanian-Turonian transition, 7. FO Watinoceras sp., 8. FO Pseudaspidoceras flexuosum, 9. FO Helvetoglobotruncana helvetica. Even though the Bahloul Formation in the Bou Ghanem site is only 7.7 m thick (from which only 2.4 m of laminated black limestones), all nine marker bio-events were recorded, almost in the same order except some small differences. A good number of these bio-events are global as they are also present at Pueblo (Colorado, USA), the stratotype for the base of the Turonian stage. Consequently, at a global scale, it is possible to place the Cenomanian-Turonian boundary with one or several of these bio-events, with a good level of confidence.
Faculty
Faculté des sciences et de médecine
Department
Département de Géosciences
Language
  • English
Classification
Geology
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/301557
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