Geomorphic evolution of the Malta Escarpment and implications for the Messinian evaporative drawdown in the eastern Mediterranean Sea

Type Article
Date 2019-02
Language English
Author(s) Micallef AaronORCID1, Camerlenghi Angelo2, Georgiopoulou AggelikiORCID3, 4, Garcia-Castellanos Daniel5, Gutscher Marc-Andre6, Lo Iacono Claudio7, Huvenne Veerle A. I.7, Mountjoy Joshu J.8, Paull Charles K.9, Le Bas Timothy7, Spatola Daniele1, Facchin Lorenzo2, Accettella Daniela2
Affiliation(s) 1 : Univ Malta, Dept Geosci, Marine Geol & Seafloor Surveying, Msida Msd 2080, Malta.
2 : Ist Nazl Oceanog & Geofis Sperimentale OGS, Trieste, Italy.
3 : Univ Coll Dublin, UCD Sch Earth Sci, Dublin, Ireland.
4 : Univ Coll Dublin, UCD Earth Inst, Dublin, Ireland.
5 : CSIC, Inst Ciencias Tierra Jaume Almera, Barcelona, Spain.
6 : Univ Brest, CNRS, Lab Geosci Ocean, IUEM, Pl N Copernic, F-29280 Plouzane, France.
7 : Univ Southampton Waterfront Campus, Natl Oceanog Ctr, Marine Geosci, European Way, Southampton, Hants, England.
8 : Natl Inst Water & Atmospher Res, Wellington, New Zealand.
9 : Monterey Bay Aquarium Res Inst, Moss Landing, CA USA.
Source Geomorphology (0169-555X) (Elsevier Science Bv), 2019-02 , Vol. 327 , P. 264-283
DOI 10.1016/j.geomorph.2018.11.012
WOS© Times Cited 22
Keyword(s) Malta Escarpment, Geomorphic evolution, Submarine canyon, Palaeoshoreline, Sea level drawdown, Messinian salinity crisis
Abstract

Carbonate escarpments are submarine limestone and dolomite cliffs that have been documented in numerous sites around the world. Their geomorphic evolution is poorly understood due to difficulties in assessing escarpment outcrops and the limited resolution achieved by geophysical techniques across their steep topographies. The geomorphic evolution of carbonate escarpments in the Mediterranean Sea has been influenced by the Messinian salinity crisis (MSC). During the MSC (5.97-533 Ma), the Mediterranean Sea became a saline basin due to a temporary restriction of the Atlantic-Mediterranean seaway, resulting in the deposition of more than one million cubic kilometres of salt. The extent and relative chronology of the evaporative drawdown phases associated to the MSC remain poorly constrained. In this paper we combine geophysical and sedimentological data from the central Mediterranean Sea to reconstruct the geomorphic evolution of the Malta Escarpment and infer the extent and timing of evaporative drawdown in the eastern Mediterranean Sea during the MSC. We propose that, during a MSC base-level fall, fluvial erosion formed a dense network of canyons across the Malta Escarpment whilst coastal erosion developed extensive palaeoshorelines and shore platforms. The drivers of geomorphic evolution of the Malta Escarpment after the MSC include: (i) canyon erosion by submarine gravity flows, with the most recent activity taking place <2600 cal. years BP; (ii) deposition by bottom currents across the entire depth range of the Malta Escarpment; (iii) tectonic deformation in the southern Malta Escarpment in association with a wrench zone; (iv) widespread, small-scale sedimentary slope failures preconditioned by oversteepening and loss of support due to canyon erosion, and triggered by earthquakes. We carry out an isostatic restoration of the palaeoshorelines and shore platforms on the northern Malta Escarpment to infer an evaporative drawdown of 1800-2000 m in the eastern Mediterranean Sea during the MSC. We interpret the occurrence of pre-evaporite sedimentary lobes in the western lonian Basin as suggesting that either evaporative drawdown and canyon formation predominantly occurred before salt deposition, or that only the latest salt deposition at the basin margin occurred after the formation of the sedimentary lobes.

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Micallef Aaron, Camerlenghi Angelo, Georgiopoulou Aggeliki, Garcia-Castellanos Daniel, Gutscher Marc-Andre, Lo Iacono Claudio, Huvenne Veerle A. I., Mountjoy Joshu J., Paull Charles K., Le Bas Timothy, Spatola Daniele, Facchin Lorenzo, Accettella Daniela (2019). Geomorphic evolution of the Malta Escarpment and implications for the Messinian evaporative drawdown in the eastern Mediterranean Sea. Geomorphology, 327, 264-283. Publisher's official version : https://doi.org/10.1016/j.geomorph.2018.11.012 , Open Access version : https://archimer.ifremer.fr/doc/00485/59686/