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Fold and thrust belt structures and strike‐slip faulting at the SE margin of the Salar de Atacama basin, Chilean Andes
Author(s) -
Kuhn Dirk
Publication year - 2002
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2001tc901042
Subject(s) - geology , transpression , foreland basin , clockwise , sinistral and dextral , seismology , fold and thrust belt , transtension , tectonics , fold (higher order function) , paleontology , strike slip tectonics , structural basin , geomorphology , mechanical engineering , engineering
A tectonic reinterpretation is reported for the southeastern margin of the Salar de Atacama basin of northern Chile. Detailed structural mapping revealed the presence of an east vergent thin‐skinned fold and thrust belt affecting Oligocene‐Miocene Paciencia Group rocks and the overlying Plio‐Pleistocene volcanic rocks. Along‐strike segmentation of the main fold implies local foreland influence on footwall ramp geometry leading to local thrust sheet rotation. To the east the adjacent western slope of the Western Cordillera displays two different structural domains, probably controlled by preexisting basement structures. The southern domain comprises two N‐S oriented sigmoidal belts of linear arranged pressure ridges, indicating left‐lateral transpression. In contrast, the northern domain is characterized by east vergent fold and thrust belt structures and reactivated NW‐SE striking sinistral strike‐slip faults, governing clockwise block rotations. An indenter‐driven deformation model is proposed to explain sinistral transpression and clockwise block rotations around vertical axes. This variant of a small‐block rotation mechanism is discussed in the context of oroclinal bending of the central Andes, emphasizing the significance of ancient structures in controlling rotations.