Neritic Carbonate Crisis During the Early Bajocian: Divergent Responses to a Global Environmental Perturbation

authored by

Stéphane Bodin, Martin Hönig, Francois-Nicolas Frédéric Krencker, Jan Danisch, Lahcen Kabiri

Abstract

The Early Bajocian witnessed a global environmental perturbation, characterized by faunal and floral turnovers and a positive carbon isotope excursion. In Italy, this environmental perturbation coincided with an eutrophication event and a carbonate crisis, but this has so far not been adequately reported from other settings, leaving doubt about the extent and nature of these phenomena. In this paper, we are reporting on an extensive neritic carbonate factory demise that occurs in the upper Lower Bajocian of Morocco, more precisely in the upper Propinquans – lower Humphriesianum Zones. This demise coincided with the acme of the global carbon isotope perturbation, recorded by a 3‰ positive carbon isotope excursion in the bulk organic matter of Morocco, but not in the micritic phase, due to the fact that the Moroccan carbonate δ

¹³C record is more sensitive to local rather than global influences. Furthermore, we observe that the Lower Bajocian of Morocco is relatively enriched in arenitic siliciclastic deposits, suggesting increased weathering and nutrient levels along the northwestern margin of Africa during the Early Bajocian. However, comparison with neighboring European basins highlights the non-uniqueness and different timing of the response of shallow-water carbonates to the Early Bajocian environmental perturbations, as some regions present no sign of carbonate factory crisis. Hence, we postulate that local factors were important in mediating the response of neritic carbonate factories to this global environmental perturbation. We notably highlight the role of large Early Bajocian sea-level fluctuation as a trigger for carbonate factory change and demise in Morocco.

Organisation(s)

Institute of Geology

External Organisation(s)

Aarhus University
Ruhr-Universität Bochum
University of Moulay Ismail (UMI)
Universite Moulay Ismail

Type

Article

Journal

Palaeogeography, Palaeoclimatology, Palaeoecology

Volume

468

Pages

184–199

No. of pages

ISSN

0031-0182

Publication date

2017

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Oceanography, Ecology, Evolution, Behavior and Systematics, Earth-Surface Processes, Palaeontology

Sustainable Development Goals

SDG 14 - Life Below Water

Electronic version(s)

https://doi.org/10.1016/j.palaeo.2016.12.017 (Access: Closed)