Analyse séquentielle d'un nouveau gisement de poissons fossiles du Messinien marin diatomitique : Masseria il Salto près de Caltagirone (Province de Catane, Sicile)

Gaudant, Jean; Caulet, J.; Geronimo, I. Di; Stefano, A. Di; Fourtanier, Elisabeth; Romeo, M.; Vénec-Peyré, Marie-Thérèse

doi:10.3406/geolm.1996.1586

Cited by 13 publications

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“…The overabundance of T. nitzschioides in the upper Miocene diatomaceous sediments of the circum-Mediterranean region has been often considered as indicative of strengthened oceanic circulation that promoted upwelling of cold, nutrient-rich and oxygen-depleted waters along the continental margins (e.g. Gaudant et al, 1996Gaudant et al, , 2006Gaudant et al, , 2010Gaudant et al, , 2015Mansour & Saint Martin, 1999;Pestrea & Saint Martin, 2002;Saint Martin et al, 2003;El Ouahabi et al, 2007;Mansour et al, 2008). This interpretation is based on the assumption that the North Pacific basins, where upwelling actually exerted a major role on the latest Miocene diatomite accumulation (e.g.…”

Section: Possible Triggers Of the Bloom Eventsmentioning

confidence: 99%

The upper Miocene diatomaceous sediments of the northernmost Mediterranean region: A lamina‐scale investigation of an overlooked palaeoceanographic archive

et al. 2020

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During the late Miocene the Mediterranean experienced a dramatic intensification of opaline accumulation, recorded by the deposition of diatomaceous sediments. The fine lamination of these deposits potentially records annual to sub-annual palaeoceanographic processes that occurred during a critical phase of the geodynamic evolution of the Mediterranean basin, which eventually led to the Messinian salinity crisis. The diatomaceous facies has been interpreted by previous researchers as the product of intensified upwelling currents and of bottom anoxia formation in the Mediterranean basin. However, until now, no efforts have been made to unravel the sedimentological and micropalaeontological content of these deposits at the lamina-scale. This paper presents the first case study of a systematic scanning electron microscope-based morphological investigation of the diatomaceous sediments deposited during the late Miocene at the northernmost offshoot of the Mediterranean basin (Piedmont Basin, northwest Italy). Using a non-invasive analytical approach, six faciological components (laminae, laminated packets, non-laminated intervals, burrows, opal-rich aggregates and mixed pelletal structures) and their relationships are described and interpreted herein. Following the lamina-scale study of these sediments, an annual sedimentary cycle could be identified and an accumulation rate (ca 50 cm kyr À1) inferred that is atypical for a setting actively influenced by upwelling. The role played by the entanglement of diatom valves in creating a physical barrier to the bioturbation is here emphasized as the main process responsible for the preservation of the laminated fabric of diatomaceous sediments, challenging the supposed role of deep anoxia. These results suggest that the late Miocene diatomaceous deposition in the Piedmont Basin cannot be univocally considered as a by-product of upwelling intensification and seafloor oxygen depletion.

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