Abstract

TURIENZO, Martín M.. Thestructure of the Malargüe fold-and-thrust belt at the Rio Diamante area (34º30'-34º50' S.L.) and itsrelationship with the Cordillera Frontal, Mendoza province. Rev. Asoc. Geol. Argent. [online]. 2009, vol.65, n.1, pp.123-139. ISSN 0004-4822.

The Malargüe fold-and-thrust belt is a thick-skinnedone developed mainly in Miocene-Pliocene times during the Andean orogeny, in Mendoza province. Based on detailed field mapping, seismicand well information, three balanced structural cross-sections were maderesulting an average shortening of 14, 2 km (24%) for basement and cover rocks.Regionally, two basement uplifts occur surrounding a central region wherethin-skinned deformation prevails. At the west, three large basement wedges areobserved related to thrust faults developed during Andean compression whichpropagated into the sedimentary cover (along the gypsum of Tábanos and AuquilcoFormations). This suggests a close spatial and temporal relationship betweenbasement and cover deformation. In the thin-skinned region, the abundance ofshales and salt horizons at the western sector promoted folding while the morecompetent units placed at the eastern zone are deformed into duplex andimbricate thrusts (Mesón and Sosneado thrusts). In the eastern region, lack ofdetachment levels in the cover rocks made difficult the development of basementwedges and instead important backthrusting occurred. Further compressionpropagates the Carrizalito fault upwards overthrusting pre-Jurassic rocks onTertiary synorogenic sediments in the north and central areas, while in thesouthern area basement structures remain in the subsurface.

Keywords : Basementstructures; Andeantectonics; CordilleraPrincipal; Balancedcross-sections; Malargüefold and thrust belt.

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