Paleozoic diamictites in the Peruvian Altiplano: evidence and tectonic implications

Striated and faceted clasts found within the diamictites of the San Gaban F ormation immediately north of Ayaviri (southeast Peru) are interpreted as e vidence for the late Ashgill-Llandovery glaciations in the Peruvian Altipla no, an area where this unit was previously considered not to be deposited. The Lower Paleozoic, stratigraphic sequence cropping out in the area includ es the Sandia, San Gaban, and Ananea Formations, and thus belongs to the Ea stern Cordillera tectonostratigraphic domain, but within the Altiplano morp hotectonic region. The marked difference between the Lower Paleozoic sequen ces of the Altiplano and Eastern Cordillera tectonostratigraphic domains su ggests important tectonic shortening along the boundary fault zone during A ndean Cenozoic deformation. (C) 2001 Elsevier Science Ltd. All rights reser ved.