Role of basin width variation on the development of inverted structures: Insight from analogue modelling and implications for the Central Andes

Abstract

The analogue models reported are intended to contribute to a better understanding of the factors that control latitudinal variations in the strike of structures during a major Cenozoic compressive event in the high central Chilean Andes, between 32° and 34° S. In this region, south of 33° S, several studies have recognized that the mostly volcanic deposits of the Abanico Formation (Eocene-Miocene) were deposited in a ~N-S oriented and ~50 km wide, highly subsident, extensional basin, with some depocenters reaching more than 3.5 km in depth (Fock et al. 2005, Charrier et al. 2002, 2007, Farías et al. 2010). This basin was subsequently inverted in early Miocene. Between 32º and 33° S, new field-based data indicate that distal facies of the Abanico Formation, outcropping in the eastern side of the Principal Andean Cordillera at this latitude, accumulated in a basin less than 10 km wide with an estimated thickness of about 3.0 to 3.5 km (Jara and Charrier 2014). In order to study the role of the basin?s width on the subsequent superimposed compressive structures formed during basin inversion and their trend, two types of models were designed to study the effect of two principal variables (basin width and shortening): Type I, homogeneous shortening on a basin of variable width, and Type II, inhomogeneous (differential) shortening on a basin of constant width.