Neogene seismotectonics of the south-central Chile margin : subduction-related processes over various temporal and spatial scales

• Main Author: Melnick, Daniel
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2007
• Subjects: ddc:550; Institut für Geowissenschaften; Antarctic; Antarc*
• Online Access: https://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/1137; https://nbn-resolving.org/urn:nbn:de:kobv:517-opus-12091; https://publishup.uni-potsdam.de/opus4-ubp/files/1137/melnick_diss.pdf

The Andean orogen is the most outstanding example of mountain building caused by the subduction of oceanic below continental lithosphere. The Andes formed by the subduction of the Nazca and Antarctic oceanic plates under the South American continent over at least ~200 million years. Tectonic and climatic conditions vary markedly along this north-south–oriented plate boundary, which thus represents an ideal natural laboratory to study tectonic and climatic segmentation processes and their possible feedbacks. Most of the seismic energy on Earth is released by earthquakes in subduction zones, like the giant 1960, Mw 9.5 event in south-central Chile. However, the segmentation mechanisms of surface deformation during and between these giant events have remained poorly understood. The Andean margin is a key area to study seismotectonic processes because of its along-strike variability under similar plate kinematic boundary conditions. Active deformation has been widely studied in the central part of the Andes, but the south-central sector of the orogen has gathered less research efforts. This study focuses on tectonics at the Neogene and late Quaternary time scales in the Main Cordillera and coastal forearc of the south-central Andes. For both domains I document the existence of previously unrecognized active faults and present estimates of deformation rates and fault kinematics. Furthermore these data are correlated to address fundamental mountain building processes like strain partitioning and large-scale segmentation. In the Main Cordillera domain and at the Neogene timescale, I integrate structural and stratigraphic field observations with published isotopic ages to propose four main phases of coupled styles of tectonics and distribution of volcanism and magmatism. These phases can be related to the geometry and kinematics of plate convergence. At the late Pleistocene timescale, I integrate field observations with lake seismic and bathymetric profiles from the Lago Laja region, located near the Andean drainage ...