Island and Coastal Aquifers - Hydrogeology: Objectives, Methods, Applications - page 78

contamination at Port Miou could therefore have occurred through a paleo-
gallery, as is suggested by a titanium anomaly discovered in the sediments
of the Port Miou gallery (Cavalera et al., 2010); the titanium could, indeed
originate from the aspiration of red clay bauxite tailings, which are dumped
in the Cassidaigne canyon.
In the region around Marseille, several coastal or submarine karst
springs with a low discharge are warm (water infl ows in the Rove tunnel
30°C, Arnette springs 30 to 35°C) (Gilli, 2002). With a gradient of 1°C per
30 m and an average surface temperature of 18°C, their salinity and their
temperature can be explained by a marine contamination at a depth of
around 350 m, and a sulfate-rich circulation near the geologic base level,
which would support the Messinian hypothesis.
3 HYPER-EUSTATISM AND ITS CONSEQUENCES
Such a model has very important consequences for the exploitation of
karst water around the Mediterranean, as it places the most transmissive
zones, the most desirable ones for drilling, at a great depth, which must be
determined individually for each case, as it depends on the maximum drop
in base level but also on the location of geologic base levels.
In addition, this model allows for reevaluation, not only of coastal
aquifers, but also of karst or alluvial aquifers in the interior of continents
(Bini, 1994), as their geometry may have been infl uenced by Messinian
downcutting (Audra et al. , 2003). This peri-Mediterranean model could also
be extended to other parts of the globe, such as the Gulf of Mexico, where the
presence of evaporites might reveal the closing and drying of the gulf.