Evolution of the Stress Field Patterns during the Construction of a Subduction-Orogenic System: TheCentral Andean Sress Field Evolution Project (CAFE)

GIAMBIAGI, LAURA; SILVANA SPAGNOTTO; PAMELA ÁLVAREZ; RODRIGO QUIROGA; DIEGO JALDIN; JOSE MESCUA; MATIAS BARRIONUEVO; ANDRÉS ECHAURREN; MACARENA BERTOA; JULIETA SURIANO; ANA LOSSADA; LUCAS LOTHARI

San Francisco

Congreso; AGU23; 2023

American Geophysical Union (AGU)

The study of the stress field patterns during the evolution of a subducted-related orogenic system, from theearly stages of compression to the formation of a large and heated plateau, is crucial for our understanding ofplate tectonic processes.The Central Andes are the result of ~100 ma of contraction along an orthogonal-to-oblique convergent subduction zone of more than 3,500 km. Two models of orogenic evolution have been proposed: (i) apunctuated contractional-stage model, with three well-identified contractional periods in the LateCretaceous, Eocene and Miocene-Quaternary; and, (ii) a continuous shortening model, at least for the last 45ma, associated with a gradual crustal thickening and foreland migration of the deformation.To shed light on this discussion, we reconstruct the stress fields acting during the construction of the Andeanorogenic system, and discuss the two proposed models for its evolution. Here we present a data baseintegrating the main structures with their kinematic and timing assigned, and more than 1,000 new andpublished stress tensors. We construct nine stress-field maps showing stress orientation and relativemagnitude. These maps represent nine evolutionary stages during the orogenic construction, and allow theidentification of three types of stages: stages dominated by tectonic stresses and characterized bycompression along and across the orogenic system; stages dominated by gravitational stresses and/or stresspartitioning and characterized by strike-slip and extension; and, stages with hybrid stress fields.