Sepiolite as paleo-CO2 barometer of dramatic climate change, and a basic element for paleogeographic reconstitution across Cretaceous–Paleogene, Asserdoune boundary, El Kouif region (Algerian–Tunisian border)

This study set out to investigate sepiolite across Cretaceous–Paleogene to demonstrate its uses as a paleo-CO 2 barometer, and to exploit it for paleogeographic reconstitution, using XRD, SEM, and fluorescence of major elements, to determine sepiolite crystallinity via calculation of the full width...

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Bibliographic Details
Published in:Carbonates and evaporites 2023-03, Vol.38 (1), p.6, Article 6
Main Authors: Djoulah, Bilel, Hamimed, Messaoud, Belghar, Nourredine, Boulemia, Salim
Format: Article
Language:English
Subjects:
Asteroid collisions
Asteroids
Barometers
Carbon dioxide
Clay minerals
Climate change
Cretaceous
Crystallization
Diagenesis
Earth and Environmental Science
Earth Sciences
Evaporation
Fluorescence
Geology
Major elements
Mineral Resources
Mineralogy
Minerals
Mud flats
Original Article
Paleogene
Saturation
Sepiolite
Shallow water
Supersaturation
Water levels
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Summary:This study set out to investigate sepiolite across Cretaceous–Paleogene to demonstrate its uses as a paleo-CO 2 barometer, and to exploit it for paleogeographic reconstitution, using XRD, SEM, and fluorescence of major elements, to determine sepiolite crystallinity via calculation of the full width at half maximum (FWHM), and the examination of the specific triplets of the well-crystallized sepiolite (WCS) at (2.61, 2.58, and 2.56 Å), in addition to its behavior towards prolonged exposure to critical pCO 2 (non-stoichiometric dissolution). The results have revealed two types of sepiolite, which are attributed to two distinct modes of occurrences. The first is well-crystallized sepiolite (WCP) consisting of spherical aggregates precipitated directly at low pCO 2 in a shallow water environment, characterized by alternating supersaturation and under-saturation conditions, reflecting a warming period synchronic to Chixculub asteroid impact. The second is poorly crystallized sepiolite (PCS) in the form of fiber, neoformed by diagenetic processes of pre-existing Mg-rich clay minerals, in neutral or slightly acidic environment, under critical pCO 2 and extreme conditions of evaporation, typical of palustrine and/or mudflat environments, marking a drop in water level (cooling period), which is attributed to nuclear winter posterior to the Chixculub asteroid impact.
ISSN:0891-2556
1878-5212
DOI:10.1007/s13146-022-00831-z