TY  - JOUR
A1  - Noury, M.
A1  - Bernet, M.
A1  - Schildgen, Taylor F.
A1  - Simon-Labric, T.
A1  - Philippon, M.
A1  - Sempere, T.
T1  - Crustal-scale block tilting during Andean trench-parallel extension: Structural and geo-thermochronological insights
JF  - Tectonics
N2  - Despite a long history of plate convergence at the western margin of the South American plate that has been ongoing since at least the Early Paleozoic, the southern Peruvian fore-arc displays little to no evidence of shortening. In the light of this observation, we assess the deformation history of the southern Peruvian fore-arc and its geodynamic implications. To accomplish this, we present a new structural and geo-thermochronological data set (zircon U-Pb, mica Ar-40/Ar-39, apatite and zircon fission-track and zircon (U-Th)/He analyses) for samples collected along a 400km long transect parallel to the trench. Our results show that the Mesoproterozoic gneissic basement was mainly at temperatures 350 degrees C since the Neoproterozoic and was later intruded by Jurassic volcanic arc plutons. Along the coast, a peculiar apatite fission-track age pattern, coupled with field observations and a synthesis of available geological maps, allows us to identify crustal-scale tilted blocks that span the coastal Peruvian fore-arc. These blocks, bounded by normal faults that are orthogonal to the trench, suggest post-60Ma trench-parallel extension that potentially accommodated oroclinal bending in this region. Block tilting is consistent with the observed and previously described switch in the location of sedimentary sources in the fore-arc basin. Our data set allows us to estimate the cumulative slip on these faults to be less than 2km and questions the large amount of trench-parallel extension suggested to have accommodated this bending.
KW  - Central Andes
KW  - Peruvian fore arc
KW  - thermochronology
KW  - trench-parallel extension
KW  - oroclinal bending
Y1  - 2016
U6  - https://doi.org/10.1002/2016TC004231
SN  - 0278-7407
SN  - 1944-9194
VL  - 35
SP  - 2052
EP  - 2069
PB  - American Geophysical Union
CY  - Washington
ER  -