Field trip guide: Andean Cordillera and backarc of the south-central Andes ( w 38.5 º Sto37º S)

ZAPATA, TOMÁS; ZAMORA VALCARCE, G.; FOLGUERA, A.; YAGUPSKY, D.

Field Trip Guides to the Backbone of the Americas in the Southern and Central Andes: Ridge Collision, Shallow Subduction, and Plateau Uplift, Field Guide

Geological Society of America

Lugar: Boulder; Año: 2008; p. 23 - 55

The Andes of the Neuquén Mesozoic basin have experienced multiple episodictectonic events as a consequence of the changes of the plate tectonic boundary confi guration.Each episode of deformation has overprinted the previous one, making it difficult to unravel the Andean tectonic history. The fi rst deformation event took place inthe uppermost Cretaceous with the formation of the Agrio fold-and-thrust belt. Thisevent was related to the shallowing of the subducting plate recorded by the migrationof the volcanic arc toward the foreland. During the late Oligocene?early Miocene, anextensional event, related to the steepening of the subducted plate, affected only thehinterland region causing the opening of the Cura Mallín basin. This basin was closedduring the late Miocene, together with the development of a new fold-and-thrust beltthat reactivated the previous structures. During the Late Tertiary, two more episodesof extension and compression affected the Andean area. The trip focuses on the fi eldevidence that documents this complex history of evolution by looking at evidence ofthe sequence of the distinct tectonic events.