Evidence of Clastic Evaporites In the Canyons of the Levant Basin (Israel): Implications For the Messinian Salinity Crisis

The recognition of large clastic sulfate deposits in the Miocene Messinian onshore of the Mediterranean Basin appears to be in contrast with the hypothesis of a complete desiccation as a consequence of the salinity crisis. Below the sea floor the evaporite facies are virtually unknown, but the detailed review of the cores from onshore Israel cutting through the evaporite filling of the marginal canyons in the Levant Basin (Mavqi’im Formation) reveal exclusively clastic sulfate facies. The rocks are graded gypsrudite and gypsarenite associated with laminar and cross-bedded gypsarenite–gypsiltite and shale, whereas no primary, in situ evaporites are present. The clastic facies association is interpreted to have been deposited by subaqueous gravity flows sourced from dismantled selenite rocks originally located eastward and updip of the canyons. The absence of supratidal evaporites suggests that no pronounced sea-level drop can be inferred during the salinity crisis because the presence of the evaporite layers at different elevations along the canyons cannot mark oscillations in sea level, but instead is the result of subaqueous mass-wasting phenomena. These findings indicate that the other ancient canyons described around the Mediterranean Basin may not be necessarily related to a base-level drop due to basinwide desiccation. On the contrary, the widespread presence of clastic evaporites suggests that a water body persisted even during the acme of the salinity crisis. The clastic deposits onshore Israel are the first direct evidence that the widespread Lower Evaporite Unit lying below the floor of the Mediterranean may actually consist of deep-water resedimented evaporites and that one of the primary sources was originally located on the upper margin of the Levant Basin. If this hypothesis is correct, then the Mediterranean Basin may host the largest clastic sulfate deposit in the world.