Timing and progression of climatic, tectonic and glacioeustatic influences on the Messinian Salinity Crisis

New palynological analysis of the continuous Upper Neogene sequence from the Rifian Corridor at Salé (Morocco) permits the deconvolution of climatic, tectonic and eustatic control on the Messinian Salinity Crisis via two indices: (1) a ‘distance-from-shore’ index based on dinoflagellate cyst versus pollen distribution, and (2) a land-climate index based on detailed pollen analysis. This new pollen analysis indicates that the Messinian Salinity Crisis (∼6.8 Ma to ∼5.3 Ma) was not associated with major climate change. Detailed analyses of dinoflagellate cyst ecology at Salé correlated to the Salé δ18O record show that initial shoaling of the Rifian Corridor after ∼7.3 Ma primarily resulted from tectonic uplift. However, from ∼6.5 Ma to ∼5.4 Ma, the Rifian Corridor was sufficiently shallow to have experienced significant restriction of Atlantic inflow during at least four small-amplitude glacioeustatic lowstands. At ∼5.4 Ma, abrupt increase in the ratio of continental- versus marine-derived palynomorphs indicates that restriction intensified as tectonic uplift significantly outpaced gradual glacioeustatic rise. Despite eustatic rise at ∼5.32 Ma, the Salé palynological data show that the Rifian Corridor experienced a second major drop in relative sea level (tectonic uplift or increased sedimentation). Therefore, termination of the Messinian Salinity Crisis was probably associated with a breach elsewhere along the Gibraltar Arc.