Single-grain TT-OSL dating results confirm an Early Pleistocene age for the lower Moulouya River deposits (NE Morocco)

Details

Serval ID
serval:BIB_608F4BA94509
Type
Article: article from journal or magazin.
Collection
Publications
Title
Single-grain TT-OSL dating results confirm an Early Pleistocene age for the lower Moulouya River deposits (NE Morocco)
Journal
Quaternary Geochronology
Author(s)
Bartz M., Arnold L.J., Demuro M., Duval M., King G.E., Rixhon G., Álvarez Posada C., Parés J.M., Brückner H.
ISSN
1871-1014
Publication state
Published
Issued date
02/2019
Peer-reviewed
Oui
Volume
49
Pages
138-145
Language
english
Abstract
The lower Moulouya River (NE Morocco) drains a tectonically active area related to the NW-SE convergence of the African and Eurasian plates. Fluvial deposits preserved in the lower Moulouya have been dated to ∼1.5–1.1 Ma, as part of a recent multi-technique geochronology study involving electron spin resonance and luminescence methods, in combination with Palaeomagnetism. The present work aims to verify and refine the existing Early Pleistocene ages for the Moulouya deposits using single-grain thermally transferred-OSL (TT-OSL) dating. The single-grain TT-OSL De distributions are characterised by high overdispersion (77–91%), significant negative skewness, and several discrete populations can be identified when applying the finite mixture model (FMM). The lowest FMM dose components of the TT-OSL datasets comprise relatively dim grains that have very slow decays. The Fast Ratio (FR) was therefore used to explore whether the presence of slower-decaying TT-OSL components might have exerted a significant effect on our De values. Our samples show a 40–50% increase in weighted mean De and a 50–100% decrease in overdispersion when applying a FR acceptance threshold of 2, resulting in the elimination of the lowest FMM component. Application of a higher FR value does not result in any additional change in TT-OSL De value. Dose recovery tests confirm the suitability of the single-grain TT-OSL protocol and use of an additional FR acceptance threshold of ≥2 for final age determination. Previous geomorphic interpretations suggested a capture event occurred at the Beni Snassen gorge between 1.04 and 1.36 Ma at the latest. This interpretation is supported by the newly obtained TT-OSL ages, which reveal that fluvial deposition occurred between ∼1.09 and ∼1.15 Ma.
Keywords
Quartz, Single-grain, TT-OSL, Fast Ratio, Fluvial terraces, Morocco
Web of science
Funding(s)
Swiss National Science Foundation / PZ00P2-167960
Create date
14/08/2018 7:36
Last modification date
23/12/2022 16:43
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