Title
Crustal-scale block tilting during Andean trench-parallel extension: Structural and geo-thermochronological insights
Date Issued
01 September 2016
Access level
open access
Resource Type
journal article
Author(s)
Université Grenoble-Alpes
Publisher(s)
Blackwell Publishing Ltd.
Abstract
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 40Ar/39Ar, apatite and zircon fission-track and zircon (U-Th)/He analyses) for samples collected along a 400 km long transect parallel to the trench. Our results show that the Mesoproterozoic gneissic basement was mainly at temperatures ≤350°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-60 Ma 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 2 km and questions the large amount of trench-parallel extension suggested to have accommodated this bending.
Start page
2052
End page
2069
Volume
35
Issue
9
Language
English
OCDE Knowledge area
Geología
Subjects
Scopus EID
2-s2.0-84987949123
Source
Tectonics
ISSN of the container
02787407
Sources of information:
Directorio de Producción Científica
Scopus