At Site 546, below the Mazagan Escarpment at a water depth of 4 km, 36 m of salt rock was cored from the top of
one of a field of salt domes. The core was studied by thin section and a variety of geochemical procedures. The salt rock
contains 0.1 to 3% carnallite and lesser amounts of sylvite and polyhalite, which with the corresponding high level of
bromide place it within the potash evaporite facies. The bromide profile is of a dominantly marine evaporite deposited
in moderately shallow brine which, however, was not repeatedly desiccated. A mineralogical argument suggests that the
brine surface was not below sea level.
An average of about 5"7o elastics, with dispersed anhydrite, darken the salt rock to deep shades of red, brown, and
gray green. Most of the included materials are in highly deformed boudins or dispersions in the salt rock that has also
undergone cataclasis in a subsequent, probably tectonic, deformation. The salt rock is slightly deficient in anhydrite,
and the usual separate beds and laminae of anhydrite are virtually absent.
Stable isotope ratios of sulfur and oxygen in the sulfate are clearly derived from sea water of Permian to Scythian
age, in contrast to the late Triassic or Early Jurassic age of evaporites onshore in Morocco and Portugal and the corresponding
evaporites offshore Maritime Canada. In contrast to those evaporites off the axis of Atlantic rifting, the salt
at Site 546 may have been deposited in a very early central rift fed by marine waters from Tethys through the Gibraltar
or South Atlas fracture zones.