Fig. 1: The Messinian Salt Giant of the Mediterranean sea.

a Study area showing data and on-land and offshore Messinian evaporite thickness distribution4 over a Mediterranean Basin map (background relief and bathymetry maps taken from https://www.geomapapp.org/). Chloride isotope data included in this work comes from the hydrocarbon industry well Aphrodite (AP2) located in the Levantine basin (eastern Mediterranean) and from Deep Sea Drilling Project (DSDP) sites 134 (western Mediterranean), 374 (Ionian Basin, eastern Mediterranean) and 376 (Florence rise, eastern Mediterranean). b location of the seismic section (red dashed line) shown in d. c Petrophysics and associated lithologic log of the Aphrodite well. GR-Gamma Ray (graph ranges between 0 – left - and 100 API) and RES-Resistivity (graph ranges between 0 – left - and 1000 Ωm; logarithmic scale) logs; d Composite seismic section (d-d’) in the Levantine basin showing the Messinian evaporites composed of seven seismo-stratigraphic units34. Notes: in a, symbols are as follows: RB, Rhodes Basin; FB, Finike Basin; AB, Antalya Basin; CB, Cilicia Basin; LRB, Larnaca Basin; LTB, Latakia Basin; LEB, Levant Basin; HB, Herodotus Basin; CYB, Cyrenaica Basin; SB, Sirte Basin; IB Ionian Basin; TB, Tyrrhenian Basin; L-PB, Liguro-Provençal Basin; ALB, Algerian Basin; in the lithological log of c, orange layers represent clastic inclusions. Black horizon in seismic section of d is a high-amplitude continuous reflection corresponding to a layer of clastics encased in halite; in d, vertical distance is in km below sea level.