Card, CJ and Montenari, M (2022) Comparative geochemistry of Early Carboniferous marine red beds (MRBs) and their significance for deep time paleoceanographic reconstructions. Sedimentary Geology. 106313 - 106313. ISSN 0037-0738

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Marine red beds (MRBs), also known as oceanic red beds (ORBs), are reddish colored sediments deposited within the marine realm that have been stained during deposition and/or early diagenesis because of changes in the ocean water chemistry in response to paleoceanographic and paleoclimatological factors. Although common throughout the Phanerozoic, marine red beds have mostly been investigated in Upper Cretaceous successions as CORBs (Cretaceous Oceanic Red Beds) - their occurrence and paleoceanographic context within the Paleozoic has yet to be studied in detail. Here we describe and interpret the high-resolution litho- and chemofacies of Early Carboniferous (Late Viséan) marine red beds from the northern coast of Menorca (Balearic Islands, Spain) that mark a rapid transition from siliceous radiolarian chert deposition to re-worked carbonate debrites followed by typical European Culm facies. The succession was deposited within a strait-like narrow basin that formed part of the Alboran-Kabylian-Peloritan-Calabrian terrane in the Western Paleotethys Ocean prior to the onset of the Variscan Orogeny. The marine red bed geochemistry is described in terms of the three geochemical endmembers Al-MRBs (clayey), Ca-MRBs (calcareous) and Si-MRBs (siliceous) by using XRF-derived Al2O3, CaO, and SiO2 concentrations. This study finds that Viséan marine red beds from Menorca are predominantly Al-MRBs with subordinate Ca-MRBs. Furthermore, we compare the bulk rock geochemistry of the Viséan marine red beds of this study with the geochemical data of Paleozoic, Mesozoic and Cenozoic marine red beds available in the existing literature (Cambrian, Silurian, Jurassic, Cretaceous, Paleogene and recent Pacific Ocean red clays) to highlight the significance of marine red bed occurrences in relation to (paleo-)bioproductivity fluctuations, deep-water oxygenation and oceanic redox transitions. This study finds that Phanerozoic marine red beds are dominantly Al-MRBs and Ca-MRBs, while Si-MRBs are less common. The Early Carboniferous marine red beds of the present study were formed in a distal, deeper-marine environment under oxic-suboxic, oligotrophic conditions. A lack of any significant Fe2O3T enrichment points towards a more complex diagenetic process for the origin of the red color imparted in Phanerozoic MRBs.

Item Type: Article
Additional Information: The final version of this article and all relevant information related to it, including copyrights, can be found on the publisher website.
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
Depositing User: Symplectic
Date Deposited: 09 Dec 2022 14:57
Last Modified: 05 Jan 2023 17:47

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