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  - 
TY  - JOUR
A1  - Cifelli, Francesca
A1  - Ballato, Paolo
A1  - Alimohammadian, Habib
A1  - Sabouri, Jafar
A1  - Mattei, Massimo
T1  - Tectonic magnetic lineation and oroclinal bending of the Alborz range: Implications on the Iran-Southern Caspian geodynamics
JF  - Tectonics
N2  - In this study we use the anisotropy of magnetic susceptibility (AMS) and paleomagnetic data for deciphering the origin of magnetic lineation in weakly deformed sedimentary rocks and for evaluating oroclinal processes within the Arabia-Eurasia collision zone. In particular, we have analyzed the Miocene Upper Red Formation (URF) from the outer curved front of the southern Central Alborz Mountains of north Iran, to test for the first time with paleomagnetic data the origin (primary versus secondary) of this orogenic arc. AMS data document the existence of a magnetic lineation parallel to the orientation of the major tectonic structures, which vary along strike from WNW to ENE. These directions are highly oblique to the paleoflow directions and hence suggest that the magnetic lineation in the URF was produced by compressional deformation during layer-parallel shortening. In addition, our paleomagnetic data document clockwise and anticlockwise rotations along vertical axis for the western and eastern sectors of the Central Alborz Mountains, respectively. Combined, our results suggest that the orogen represents an orocline, which formed not earlier than circa 7.6Ma most likely through bending processes caused by the relative motion between the rigid crustal blocks of the collision zone. Moreover, our study provides new insights into the Iran-Southern Caspian Basin kinematic evolution suggesting that the present-day SW motion of the South Caspian Basin with respect to Central Iran postdates oroclinal bending and hence cannot be as old as late Miocene to early Pliocene but a rather recent configuration (i.e., 3 to <1Ma).
KW  - oroclinal bending
KW  - magnetic fabric
KW  - Alborz range
KW  - Southern Caspian Basin
Y1  - 2015
U6  - https://doi.org/10.1002/2014TC003626
SN  - 0278-7407
SN  - 1944-9194
VL  - 34
IS  - 1
SP  - 116
EP  - 132
PB  - American Geophysical Union
CY  - Washington
ER  -