The Andean orogenic front at Sierra de Las Penas-Las Higueras, Mendoza, Argentina

The Sierra de Las Perias-Las Higueras (Mendoza Province, Argentina, 32 degr ees 15'S-32 degrees 45'S) presents one of the dearest and most continuous e xposures of the Quaternary thrust front of the Precordilleran fold-and-thru st bell. It is characterized by an east-verging thrust that breaks the surf ace and causes Neogene sedimentary rocks to override Quaternary alluvial co nglomerates. Monoclinal folds and progressive unconformities are characteri stic of deformation in the upper part of the alluvial cover, indicating syn chronous development of sedimentation and thrusting during the Quaternary. South of this range, ongoing deformation is by gentle warping of the piedmo nt alluvial plain, hiding blind thrusts at depth. (C) 2000 Elsevier Science Ltd. All rights reserved.