Journal of Structural Geology xxx (2018) xxx-xxx
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Journal of Structural Geology
PR OO F
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Basin inversion and magma migration and emplacement: Insights from basins of northern Chile Fernando Mart neza , , Domenico Montanarib , Chiara Del Ventisettec , Marco Boninib , Giacomo Cortib a b c
Facultad de Ingeniería y Geología, Departamento de Geología, Universidad Cató lica del Norte, Angamos, 0610, Antofagasta, Chile Consiglio Nazionale delle Ricerche (CNR), Instituto di Geoscienze e Georisorse, Via G. La Pira 4, Florence, 50121, Italy Earth Sciences Department, University of Florence, Via G. La Pira 4, Florence, 50121, Italy
ABSTRACT
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ARTICLE INFO
One of the major problems found during the structural modeling of inverted basins inRuenced by magmatism is the understanding of the geometric and kinematic relationships between inverted structures and intrusive bodies. The Central Andes of northern Chile is a natural laboratory to analyze this situation, since its Cenozoic tectonic evolution was marked by the tectonic inversion of Mesozoic extensional-related back arc basins, which occurred simultaneously with the emplacement of km-scale intrusions. In order to provide some insights on the interplay between basin inversion and magma emplacement, we have completed a comparative analysis based of Qeld data from four inverted Mesozoic basins of northern Chile and a series of previous and new analogue models reproducing the tectonic inversion of half-grabens and simultaneous magma emplacement. The results of the experiments showed a strong correlation with the natural cases analyzed. Magma migration and emplacement during basin inversion was controlled by the initial distribution of normal faults. The magma migration occurred in the same direction of the tectonic transport preferentially along the inverted normal faults. High magma injection rate during basin inversion can cause a major reactivation of the normal faults, favoring a comparatively increase in bulk shortening. The most favorable condition for which the magma reaches the surface during basin inversion is under simultaneous high magma injection and shortening rates. The latter allow the magma to be emplaced along the core of inversion related anticlines such as it is recognized in northern Chile.
1. Introduction
Basin inversion involves the reactivation of pre-existing extensional faults during shortening (Butler, 1989; Cooper and Williams, 1989). This process is controlled by several factors, such as the orientations of the pre-existing normal faults relative to the maximum compressive stress ( 1 max), the initial dip angles of normal faults, the presence of Ruids and the rheological characteristics of the deformed materials (Sibson, 1995; Coward et al., 1991; Del Ventisette et al., 2005; Turner and Williams, 2004; Del Ventisette et al., 2006; Bonini et al., 2012; Granado et al., 2017; among others). Evidence for this phenomenon has been in many geological provinces of the Central Andes of South America that have experienced
crustal shortening following major periods of extension and subsidence. The main evidences are founded in sedimentary basins in Chile, Peru, and Argentina (Giambiagi et al., 2005; Carrera et al., 2006; Amilibia et al., 2008; Mart nez et al., 2012; P rez et al., 2016), most of which has been identiQed from seismic reRection proQles and Qeld data. The northern Chile (27 29 S; Fig. 1) in the western Central Andes provides a natural laboratory for analyzing inverted structures, based on its climate conditions and deep canyons that expose the structural relationships between the extensional and contractional deformation patterns resulting from the Mesozoic and Cenozoic tectonic evolution of the region. In this region, the main inverted structures have been associated with the closure and shortening of ancient Mesozoic
Corresponding author. Email address:
[email protected] (F. Martínez)
https://doi.org/10.1016/j.jsg.2017.12.008 Received 13 October 2017; Received in revised form 7 December 2017; Accepted 13 December 2017 Available online xxx 0191-8141/ © 2017.
