Smooth folds favoring gypsum precipitation in the Messinian Poniente marginal basin (Western Mediterranean)

- We reconstruct the 3D geometry of the folded Poniente Basin.
- The folds accommodated 52 m/Ma shortening in the last 7.2 Ma.
- Fold development favored Messinian evaporite deposition in peripheral basins.

The Poniente Basin lies in a folded sector located at the boundary between the eastern Betic Cordillera and the Alborán Sea. We reconstruct its 3D geometry combining depth-migrated 2D seismic reflection sections with borehole and surface structural data. The folds have been interplaying with sedimentation since late Miocene time. Growth strata allow us to reconstruct both the folding history and the average shortening rate. Two isolated antiforms began to grow during the late Tortonian, separated by an antiformal saddle point. A rectilinear fold-linkage sector between initially isolated short segments developed during the Messinian, eventually forming a subcylindrical ENE-WSW-trending antiform that has continued growing symmetrically since the Pleistocene. The antiform formed a barrier that favored Messinian evaporite deposition along the contiguous synform to the north. The vertical breakup between the lower parts of the synform and the barrier anticline culmination ranges from 500 to 700 m. In the last 7.2 Ma, the analyzed folds accommodated a shortening of 52 m/Ma along a 20 km-wide band. At a Mediterranean scale, our study sheds light on the propagation mode of barriers that favor the precipitation of gypsum in peripheral basins by restricting water exchange with the open sea, before the main phase of evaporite deposition occurred in the deep basin.