Collision of the Mocha fracture zone and a <4 Ma old wave of orogenic uplift in the Andes (36°–38°S)

The southern Central and northern Patagonian Andes (34°–45°S) are characterized by low to no crustal seismicity at the retroarc fold and thrust belt, in contrast to the Pampean flat subduction zone located immediately to the north (27°–33°30′S). Detailed examination of this area shows no indication of contractional neotectonics with the exception of the segment located between 36° and 38°S. There, out-of-sequence transpressional deformation, initially developed in the 1.7–1.4 Ma interval, affects the western retroarc between 36° and 38°S next to the arc zone. It is between these latitudes that contractional deformation