Details
| Original language | English |
|---|---|
| Pages (from-to) | 47–69 |
| Number of pages | 23 |
| Journal | Newsletters on Stratigraphy |
| Volume | 50 |
| Issue number | 1 |
| Publication status | Published - 2017 |
Abstract
The Pliensbachian-Toarcian transition has been studied in depth for the major environmental changes and the marine invertebrate biodiversity crisis observed at that time. Despite a large number of studies performed, the time frames provided for this interval show large discrepancies from author to author. Major environmental changes occurring at that time impacted the sedimentation pattern and sedimentation rates, making uncertain the construction of time scales. Here, we provide a new astrochronological framework based on an expanded hemipelagic section from the Central High Atlas Basin (Morocco). δ 13C and CaCO 3 measurements performed on the studied section allowed the construction of an orbital time scale based on the 405-kyr eccentricity and the obliquity cycles. This orbital time scale is then compared to the Peniche section (GSSP of the Toarcian Stage) in order to limit the effects of eventual condensation and erosion events on the construction of the orbital time scale. The duration of the early Toarcian Polymorphum Zone is then assessed at 0.9-1.0 myr, while the interval from the base of the Toarcian Stage to the FO of C. superbus is assessed at 0.51 myr. This long duration of the Polymorphum Zone highlights the fact that numerous sections in Europe are affected by long-term condensation and hiati around the Pliensbachian-Toarcian transition. Finally, we also explore the potential of the Central High Atlas basin to provide a refined time scale for the late Pliensbachian. Preliminary data lead to a duration assessment of the NJ5b calcareous nannofossil zone of at least 2.07 myr, and to a mean duration of the Emaciatum ammonite zone of 2.05 myr. These durations are ~ 1 myr longer than the durations proposed in the Geological Time Scale 2012, which illustrates the potential of the Central High Atlas Basin for calibrating the Pliensbachian times.
Keywords
- Carbon-isotopes, Cyclostratigraphy, High atlas, P-To event, Pliensbachian, Toarcian
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Stratigraphy
Sustainable Development Goals
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In: Newsletters on Stratigraphy, Vol. 50, No. 1, 2017, p. 47–69.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Orbital Chronology of the Pliensbachian–Toarcian Transition From the Central High Atlas Basin (Morocco)
AU - Martinez, Mathieu
AU - Krencker, Francois-Nicolas Frédéric
AU - Mattioli, Emanuela
AU - Bodin, Stéphane
N1 - Publisher Copyright: © 2016 The authors.
PY - 2017
Y1 - 2017
N2 - The Pliensbachian-Toarcian transition has been studied in depth for the major environmental changes and the marine invertebrate biodiversity crisis observed at that time. Despite a large number of studies performed, the time frames provided for this interval show large discrepancies from author to author. Major environmental changes occurring at that time impacted the sedimentation pattern and sedimentation rates, making uncertain the construction of time scales. Here, we provide a new astrochronological framework based on an expanded hemipelagic section from the Central High Atlas Basin (Morocco). δ 13C and CaCO 3 measurements performed on the studied section allowed the construction of an orbital time scale based on the 405-kyr eccentricity and the obliquity cycles. This orbital time scale is then compared to the Peniche section (GSSP of the Toarcian Stage) in order to limit the effects of eventual condensation and erosion events on the construction of the orbital time scale. The duration of the early Toarcian Polymorphum Zone is then assessed at 0.9-1.0 myr, while the interval from the base of the Toarcian Stage to the FO of C. superbus is assessed at 0.51 myr. This long duration of the Polymorphum Zone highlights the fact that numerous sections in Europe are affected by long-term condensation and hiati around the Pliensbachian-Toarcian transition. Finally, we also explore the potential of the Central High Atlas basin to provide a refined time scale for the late Pliensbachian. Preliminary data lead to a duration assessment of the NJ5b calcareous nannofossil zone of at least 2.07 myr, and to a mean duration of the Emaciatum ammonite zone of 2.05 myr. These durations are ~ 1 myr longer than the durations proposed in the Geological Time Scale 2012, which illustrates the potential of the Central High Atlas Basin for calibrating the Pliensbachian times.
AB - The Pliensbachian-Toarcian transition has been studied in depth for the major environmental changes and the marine invertebrate biodiversity crisis observed at that time. Despite a large number of studies performed, the time frames provided for this interval show large discrepancies from author to author. Major environmental changes occurring at that time impacted the sedimentation pattern and sedimentation rates, making uncertain the construction of time scales. Here, we provide a new astrochronological framework based on an expanded hemipelagic section from the Central High Atlas Basin (Morocco). δ 13C and CaCO 3 measurements performed on the studied section allowed the construction of an orbital time scale based on the 405-kyr eccentricity and the obliquity cycles. This orbital time scale is then compared to the Peniche section (GSSP of the Toarcian Stage) in order to limit the effects of eventual condensation and erosion events on the construction of the orbital time scale. The duration of the early Toarcian Polymorphum Zone is then assessed at 0.9-1.0 myr, while the interval from the base of the Toarcian Stage to the FO of C. superbus is assessed at 0.51 myr. This long duration of the Polymorphum Zone highlights the fact that numerous sections in Europe are affected by long-term condensation and hiati around the Pliensbachian-Toarcian transition. Finally, we also explore the potential of the Central High Atlas basin to provide a refined time scale for the late Pliensbachian. Preliminary data lead to a duration assessment of the NJ5b calcareous nannofossil zone of at least 2.07 myr, and to a mean duration of the Emaciatum ammonite zone of 2.05 myr. These durations are ~ 1 myr longer than the durations proposed in the Geological Time Scale 2012, which illustrates the potential of the Central High Atlas Basin for calibrating the Pliensbachian times.
KW - Carbon-isotopes
KW - Cyclostratigraphy
KW - High atlas
KW - P-To event
KW - Pliensbachian
KW - Toarcian
UR - http://www.scopus.com/inward/record.url?scp=85008698656&partnerID=8YFLogxK
U2 - 10.1127/nos/2016/0311
DO - 10.1127/nos/2016/0311
M3 - Article
VL - 50
SP - 47
EP - 69
JO - Newsletters on Stratigraphy
JF - Newsletters on Stratigraphy
SN - 0078-0421
IS - 1
ER -