The Messinian Salinity Crisis deposits in the Balearic Promontory: An undeformed analog of the MSC Sicilian basins??

Abstract

The Messinian Salinity Crisis (MSC) is a controversial geological event that influenced the Mediterranean Basin in the late Miocene leaving behind a widespread Salt Giant. Today, more than 90% of the Messinian evaporitic deposits are located offshore, buried below the Plio-Quaternary sediments and have thus been studied mainly by marine seismic reflection imaging.Onshore-offshore records' comparisons and correlations should be considered a key approach to progress in our understanding of the MSC.2 This approach has however not been widely explored so far. Indeed, because of the erosion on the Messinian continental shelves and slopes during the MSC, only few places in the Mediterranean domain offers the opportunity to compare onshore and offshore records that have been preserved from erosion. In this paper, we compare for the first time the MSC records from two basins that were lying at intermediate water depths during the MSC and in which salt layers emplaced in topographic lows: the Central Mallorca Depression (CMD) in the Balearic Promontory, and the Caltanissetta Basin (CB) in Sicily. The reduced tectonic movements in the CMD since the late Miocene (Messinian) till recent days, favored the conservation of most of the MSC records in a configuration relatively close to their original configuration, thus allowing a comparison with the reference records outcropping in Sicily. We perform seismic interpretation of a wide seismic reflection dataset in the study area with the aim of refining the mapping of the Messinian units covering the Balearic Promontory (BP) and restituting their depositional history based on a detailed comparison with the Messinian evaporitic units of the Sicilian Caltanissetta Basin. We discuss how this history matches with the existing 3-stages chrono-stratigraphic model. We show that the Messinian units of Central Mallorca Depression could be an undeformed analog of those outcropping on-land in the Sicilian Caltanissetta Basin, thus questioning the contemporaneous onset of the salt deposition on the Mediterranean scale. We show a change in seismic facies at a certain range of depth between stage 1 MSC units, and wonder if this could reflect the threshold/maximum depth of deposition of bottom growth PLG selenites passing more distally to pelagic snowfall cumulate gypsum. Moreover, we confirm that PLG could be deposited in water depths exceeding 200m.

Flexural‐isostatic reconstruction of the Western Mediterranean during the Messinian Salinity Crisis: Implications for water level and basin connectivity

“…No age control exists for the deep MSC record in the Western Mediterranean and some authors question its age and origin (e.g. Raad et al., 2021). Moreover, the passage from pre‐MSC sediment to evaporitic facies marking the onset of the MSC has been proven to be conformable all around the Mediterranean with no evidence of water level drop at this stage (Dela Pierre et al., 2011; Lugli et al., 2010; Ochoa et al., 2015).…”

“…The distribution of the MSC sedimentary sequences is used to define paleoshoreline indicators that constrain our model. They have been identified and widely studied and described mainly from seismic datasets by several authors (Camerlenghi et al., 2009; Cameselle & Urgeles, 2017; Dal Cin et al., 2016; Driussi et al., 2015; Lofi, Sage, et al., 2011; Maillard et al., 2006; Ochoa et al., 2015; Urgeles et al., 2011; Lofi, 2018 and references therein; Pellen et al., 2019; Raad et al., 2021).…”

“…Raad et al. (2021) interpreted the MSC units of the Central Mallorca Depression as an undeformed analog of the Sicilian MSC records. They recognised the equivalent of the PLG, salt and Upper Evaporites (UE).…”

“…Evaporite deposits in the deep basins of the Western Mediterranean have not yet been drilled beyond their topmost layer, and due to the extreme conditions during their deposition they lack biostratigraphic water depth proxies. The main evidence supporting water level variations are erosional surfaces observed in outcrops in marginal basins (Bourillot et al., 2009, 2010; Clauzon et al., 1996, 2015; Conesa & Badinot, 1999; Dabrio & Polo Camacho, 1995; Decima & Wezel, 1967; Dela Pierre et al., 2011; Do Couto et al., 2015; Dronkert, 1976; Fortuin et al., 2000; Krijgsman et al., 2001; Ott d’Estevou & Montenat, 1990; Pagnier, 1976; Riding et al., 1991; Rouchy & Saint Martin, 1992; Roveri et al., 2009; Vai & Lucchi, 1977) and in the offshore seismic record underlying, intercalated in, and on top of the Messinian deposits, pointing to a kilometric water level drop or (near) desiccation of large parts of the Mediterranean (Lofi, Déverchère, et al., 2011; Lofi et al., 2005; Lofi, Sage, et al., 2011; Maillard et al., 2006; Raad et al., 2021; Ryan, 1976; Ryan & Cita, 1978). The MSC ended abruptly with a geologically sudden reestablishment of open marine conditions, purportedly due to reflooding through the Strait of Gibraltar causing a deeply eroded channel in the Alboran basin and chaotic deposits associated with the flooding event (Blanc, 2002; Estrada et al., 2011; Garcia‐Castellanos et al., 2009, 2020; Micallef et al., 2018).…”

Tiny, glassy, and rapidly trapped: The nano-sized planktic diatoms in Messinian (late Miocene) gypsum

“…The depth of marginal basins during Messinian gypsum deposition is another debated issue. The proposed depths range from very shallow (upper photic zone; Rouchy and Monty, 2000) to ≤200 m (within the photic zone; Roveri et al, 2014) to >200 m (below the photic zone; Raad et al, 2020). The benthic-epiphytic diatoms preserved in the studied crystals cannot be used to constrain deposition in the photic zone.…”