Unidades evaporíticas eocenas de la Zona Surpirenaica Oriental (Área de La Garrotxa)

Abstract

Three Eocene evaporite units are distinguished in La Garrotxa area (Southeastern Pyrenean Zone, NE Spain) on the basis of geological mapping with integrated sedimentological, structural and borehole data. These units were deposited in a foreland basin during Lutetian time: (1) the oldest and thickest one, the Borró Evaporitic Unit, was deposited in both platform setting and slope-basin environments, previously to the turbidite deposition of the Vallfogona Formation, (2) the Beuda Gypsum Unit was deposited overlying these turbidites, with no differentiated paleogeographical environments, and (3) the youngest and thinnest one, the Besalú Gypsum Unit, was deposited in a siliciclastic platform, just before the change from marine to continental conditions in the basin. As a whole, this evaporitic evolution reflects decreasing intensity in the successive salinity crises in the foreland basin in parallel with its progressive filling and loss of marine influence