LATE CENOZOIC DEFORMATION IN THE CENTRAL ANDES - FAULT KINEMATICS FROM THE NORTHERN PUNA, NORTHWESTERN ARGENTINA AND SOUTHWESTERN BOLIVIA

被引:96
作者
CLADOUHOS, TT [1 ]
ALLMENDINGER, RW [1 ]
COIRA, B [1 ]
FARRAR, E [1 ]
机构
[1] CORNELL UNIV,DEPT GEOL SCI,ITHACA,NY 14853
关键词
D O I
10.1016/0895-9811(94)90008-6
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
Fault kinematics from the northern Puna region of the Central Andean Plateau show two phases of deformation. The older deformation involved thrusting on NNE-SSW striking faults prior to about 9 Ma. This produced an average shortening direction (120-degrees +/- 20-degrees) which does not overlap the Miocene-to-Recent convergence direction between the Nazca and South American Plates (82-degrees +/- 4-degrees). Reactivation of normal faults associated with a Cretaceous rift and strike-slip faulting in the weakened magmatic arc can explain the approximately 40-degrees discrepancy. Deformation younger than 9 Ma is on normal and strike-slip faults that indicate diverse Plio-Quaternary strain orientations, possibly due to the influence of both gravitational and subduction forces. While the normal faults are minor, five orogen parallel (NS) strike-slip faults are marked by ten- to sixty-kilometer-long scarps. Striae indicate right-lateral strike-slip with minor normal displacement. At least two of these faults reactivate older thrusts. By analogy with trench-linked forearc strike-slip faults, the kinematics of these back-arc strike-slip faults can be explained by the decoupling of oblique foreland convergence into two mutually orthogonal components.
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页码:209 / 228
页数:20
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