Title
Synchronous onset of the Messinian evaporite precipitation: First Mediterranean offshore evidence
Date Issued
01 October 2015
Access level
metadata only access
Resource Type
journal article
Author(s)
Universidad de Salamanca
Publisher(s)
Elsevier
Abstract
The Messinian Salinity Crisis (MSC) was a major ecological crisis affecting shallow and deep-water settings over the entire Mediterranean basin. However, the evolution of the MSC and its ecological impacts have mainly been explained on the basis of sediments from onshore outcrops. Lack of complete and physically connected records from onshore and offshore settings has inhibited comprehensive understanding of basin behaviour during the MSC. Herein we present a continuous record from an intermediate-depth basin on the Balearic Promontory that comprises late Tortonian-Messinian marls and evaporitic beds from the first MSC phase (i.e., Primary Lower Gypsum-PLG stage). Well-log and biostratigraphic data allow us establishing a large-scale calibration to the astronomical solutions, and to correlate pre-MSC sediments with classical rhythmic successions outcropping onshore. Thickness and characteristic sedimentary patterns observed in the offshore evaporitic records resemble those from marginal PLG sequences. Furthermore, seismic reflectors from a Bedded Unit (BU), which corresponds to an evaporitic interval according to well-to-seismic ties, are correlated with the onshore PLG sequences. This correlation constitutes the first attempt to link well-known marginal sequences with intermediate-depth offshore settings, which have previously only been studied through seismic imaging. Our time-calibration provides direct evidence supporting a synchronous onset of the PLG phase between onshore and offshore settings along the southwestern Balearic Promontory margin. Those BU reflectors, which were positively correlated to the PLG, were likely precipitated offshore the continental shelf at Messinian times. These results suggest that gypsum precipitation and/or preservation was not always limited to 200 m water-depths and could occur in non-silled basins. Finally, we only found a major erosion at the top of the PLG sequences, implying that the MSC drawdown occurred after the precipitation of the onshore lower evaporites. Studied sequences provide new insights into the PLG precipitation/preservation settings, as well as into the land-sea correlations of MSC units, and thus could potentially help refine current MSC models.
Start page
112
End page
124
Volume
427
Language
English
OCDE Knowledge area
Geología
Subjects
Scopus EID
2-s2.0-84937131139
Source
Earth and Planetary Science Letters
ISSN of the container
0012-821X
Sponsor(s)
The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007–2013/ under REA Grant Agreement No. 290201 MEDGATE. REPSOL-Spain and the Instituto Geológico y Minero de España-IGME are thanked for providing access to data and samples. D. Ochoa specially thanks R. Flecker and the MEDGATE team (researchers, staff, partners and associates) for their constructive comments, support and scientific discussions. We acknowledge Bill Ryan, Derek Vance, and two anonymous reviewers for their useful comments, which help improving this manuscript.
Sources of information:
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