Climatic and tectonic controls on ferroan dolomite formation – insights on Early Miocene Mediterranean anoxia (il-Blata, Malta)

Zammit, Ray, Petrash, D.A. and Bialik, O.M. 2025. Climatic and tectonic controls on ferroan dolomite formation – insights on Early Miocene Mediterranean anoxia (il-Blata, Malta). Journal of the Geological Society 10.1144/jgs2024-146

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Abstract

Records from the Miocene il-Blata section in Malta offer insights into the Central Mediterranean's depositional environments following an Early Miocene restriction of the Mesopotamian Seaway (∼20 Ma). Inorganic and organic stable carbon isotope values suggest relatively steady depositional environments, whereas authigenic Fe-dolomite abundances exhibiting substantial δ 18 O and δ 13 C variations at a sequence-scale indicate dynamic sedimentation conditions leading to differential diagenesis. Petrographically, the dolomitic levels exhibit matrix-selective dolomitisation, occasional silicification and phosphatisation, and textural indicators pointing to subsurface microbial influence which collectively point to complex shallow burial diagenesis. In addition, the presence of framboidal pyrite and gypsum infilling foraminiferal chambers along with the absence of large planktonic foraminifera, suggests the development of paleoenvironmental stress imposed by a density-stratified water column affecting pore waters. Towards the top of the studied succession, a shift from organic to siliceous deposits reflects water column perturbations possibly linked to changes in oceanic circulation associated with a temporary re-opening of the Mesopotamian Seaway. This study not only underscores hydrochemical controls exerted by North African terrigenous fluxes over the Mediterranean, but also highlights the intricate interplay between shifting depositional environments and shallow burial diagenetic processes in shaping the geochemical and textural fabrics of authigenic mineral assemblages.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Earth and Environmental Sciences
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/, Start Date: 2025-01-15
Publisher:	The Geological Society
ISSN:	0016-7649
Date of First Compliant Deposit:	24 January 2025
Date of Acceptance:	2 January 2025
Last Modified:	24 Jan 2025 14:30
URI:	https://orca.cardiff.ac.uk/id/eprint/175565

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