Premium
Kinematic constraints on intra‐arc shear and strain partitioning in the southern Andes between 38°S and 42°S latitude
Author(s) -
Rosenau Matthias,
Melnick Daniel,
Echtler Helmut
Publication year - 2006
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2005tc001943
Subject(s) - geology , sinistral and dextral , clockwise , kinematics , geodesy , seismology , shear zone , shear (geology) , latitude , arc (geometry) , fault (geology) , strain partitioning , displacement (psychology) , vertical displacement , geometry , rotation (mathematics) , tectonics , geomorphology , paleontology , psychology , physics , mathematics , classical mechanics , psychotherapist
On the basis of structural field work, fault kinematic analysis, and the analysis of digital imagery, we describe the northern part of the southern Andean intra‐arc Liquiñe‐Ofqui Fault Zone (LOFZ) as an SC‐like fault zone system accommodating part of the Nazca–South American plate convergence obliquity. Kinematic modeling suggests that the LOFZ accommodated 124 (+24/−21) km of dextral displacement between 40°S and 42°S and 67 (+13/−11) km between 38°S and 40°S since the Pliocene. Associated vertical axis rotations are 31 ± 4° clockwise and 9 ± 1° counterclockwise along synthetic and antithetic faults, respectively. Mean Pliocene to recent shear rates along the LOFZ decrease northward from 32 ± 6 mm/yr to 13 ± 3 mm/yr compatible with partitioning of half of the convergence obliquity into the intra‐arc zone north of 40°S and complete partitioning to the south. The displacement gradient along the intra‐arc zone results in margin‐parallel shortening of the fore arc.