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The Las Ollas Complex consists of a pile of tectonic nappes, which vary in size from the decameter to the kilometer scale. The lowermost structural levels are exposed at the cores of kilometric–scale anticlines and are composed of amphibolite schist finely interlayered with phyllite, quartzite, and scarce metatuff. Amphibolite schists are constituted by nematoblastic layers of green hornblende + titanite ± biotite ± oxides alternating with granoblastic layers of quartz ± muscovite. Amphibolites are overthrusted by greenschist to low greenschist metamorphic rocks, represented by actinolite schists finely interlayered with quartzite and phyllite. The former are composed by millimeter to centimeter nematoblastic levels of actinolite + titanite ± chlorite finely alternating with granoblastic levels of quartz ± muscovite. Metasedimentary rocks of the Las Ollas Complex enclose exotic blocks of banded metagabbro, amphibolite, serpentinite, metabasalt, dunite, plagiogranite, and quartzite, which vary in size from the decimeter to the kilometer scale. In the study area we did not find the blueschist paragenesis reported by Talavera–Mendoza (2000), perhaps due to pervasive retrograde metamorphism associated with the exhumation of these nappes. The metamorphic rocks of the Las Ollas Complex experienced polyphasic shortening, with a first NW–SE trending isoclinal folding that is not recorded in the overlying Cretaceous–Paleogene tectono–stratigraphic assemblages (Martini and Ferrari, submitted).