Abstract
The Messinian salinity crisis was an extraordinary event that resulted in the deposition of kilometre-thick evaporite sequences in the Mediterranean Sea after the latter became disconnected from the world's oceans. The return to fully and stable marine conditions at the end of the crisis is still subject to debate. Three main hypotheses, based on geophysical and borehole data, onshore outcrops and climate simulations, have been put forward. These include a single-stage catastrophic flood, a two-step reflooding scenario, and an overspill of Paratethyan water followed by Atlantic inflow. In this study, two research questions are addressed: (i) Which event marked the termination of the Messinian salinity crisis? (ii) What was the sea level in the eastern Mediterranean Sea during this event? Geophysical data from the western Ionian Basin are integrated with numerical simulations to infer that the termination of the crisis consisted of a single-stage megaflood following a sea level drawdown of 1900 m. This megaflood deposited an extensive sedimentary body with a chaotic to transparent seismic signature at the base of the Malta Escarpment. Fine, well-sorted sediments are predicted to have been deposited within the thicker sections of the flood deposit, whereas a more variable distribution of coarser sediments is expected elsewhere. The north-western Ionian Basin hosts evidence of episodic post-Messinian salinity crisis slope instability events in the last ~1.8 Ma. The largest of these emplaced a >200 km3 deposit and is associated with failure of the head of Noto Canyon (offshore SE Sicily). Apart from unravelling the final phase of the Messinian salinity crisis and the ensuing stratigraphic evolution of the western Ionian Basin, our results are also relevant to better understand megafloods, which are some of the most catastrophic geological processes on Earth and Mars.
Highlights
60 61 The Messinian salinity crisis (MSC) was an extraordinary, short-term (~ 640 ka), geological, oceanographic and ecological event that occurred between 5.97 and 5.33 Ma and that had local to global consequences (Gennari et al, 2013; Meilijson et al, 2019; Rouchy and Caruso, 2006; Roveri et al, 2014; Ryan, 2009)
We address two specific research questions: (i) which event marked the termination of the MSC?; and (ii) what was the sea level in the eastern Mediterranean Sea during this event? We tackle these questions by first analysing 2D seismic reflection profiles from the western Ionian Basin to reconstruct its stratigraphic evolution and identify evidence for megaflood deposition
Our study is based on the following geophysical data sets collected from the Malta Escarpment and the western Ionian Basin between 1969 and 2015 (Figure 1): (i) Multibeam echosounder bathymetry data: Multibeam echosounder data sets acquired during three oceanographic cruises - (i) R/V Suroît, CIRCEE-HR, 2013
Summary
60 61 The Messinian salinity crisis (MSC) was an extraordinary, short-term (~ 640 ka), geological, oceanographic and ecological event that occurred between 5.97 and 5.33 Ma and that had local to global consequences (Gennari et al, 2013; Meilijson et al, 2019; Rouchy and Caruso, 2006; Roveri et al, 2014; Ryan, 2009). Following the Messinian phase of salt deposition under hypersaline conditions, there was a transition to a phase of sediment deposition in a freshwater environment, which is represented by the so-called “Lago-Mare” sedimentary facies These facies contain microfossils originating from the eastern part of the Mediterranean Sea, from the so-called Neogene ‘Paratethys basin’ (Carpathian and Black Sea areas) Evidence for the deposition of the material eroded by the postulated Zanclean flood in the Strait of Gibraltar has been identified This includes a series of elongated sedimentary bodies at the base of the Pliocene in the Alborán Sea that are 35 km long, 160 m thick and up to 7 km wide. These deposits may suggest that an initial overspill of Paratethyan water, derived from the former Black Sea, entered the Mediterranean Basin and was followed by Atlantic inflow once the Mediterranean
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
