Stress fields recorded on large-scale strike-slip fault systems: Effects on the tectonic evolution of crustal slivers during oblique subduction

Veloso, Eugenio E.; Gomila, Rodrigo; Cembrano, José; González, Rodrigo; Jensen, Erik; Arancibia, Gloria

doi:10.1016/j.tecto.2015.09.022

Cited by 38 publications

(24 citation statements)

References 49 publications

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“…Three major segments of the fault system (the Salar del Carmen, Paposo, and El Salado segments) are composed of several parallel branches rather than a single throughgoing fault plane and together comprise the ~1,000‐km fault system (Figure a). Motion along the AFS was dominantly sinistral strike slip with variable components of extension or shortening (Grocott & Taylor, ; Ruthven et al, ; Scheuber & Andriessen, ; Veloso et al, ). The NW striking Taltal fault system cuts the AFS (Arabasz, ; Mavor et al, ).…”

Section: Geologic Backgroundmentioning

confidence: 99%

The Relationship Between Magmatism and Deformation Along the Intra‐arc Strike‐Slip Atacama Fault System, Northern Chile

et al. 2020

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Magmatic arcs may play a major role in the initiation, behavior, and abandonment of intra-arc strike-slip systems. Here we present zircon U-Pb and (U-Th)/He geochronology/thermochronology with new mapping to relate Coastal Cordillera arc magmatism to sinistral shear along the Atacama fault system (AFS) in northern Chile. New dates from 18 intrusions along the AFS between 24.6°S and 27°S compiled with published data record a minor Early Jurassic magmatic pulse , broad latest Jurassic to Early Cretaceous (150-120 Ma) pulse, and a minor younger (120-105 Ma) pulse. Mylonitization occurred only along the margins of Early Cretaceous plutons and surrounding Paleozoic metasedimentary rock, whereas Jurassic plutons and metasedimentary rocks away from Early Cretaceous plutons lack mylonitic fabrics. Early Cretaceous magmatism facilitated AFS deformation by thermally weakening the crust with elevated geothermal gradients that enabled mylonitization to take place at~5-to 7-km depths and low stresses. Spatial variability of pluton emplacement produced significant rheological heterogeneity, giving rise to a highly segmented fault system that did not originate as a regional-scale shear zone. Synkinematic dikes (~120-117 Ma) cut mylonitic fabrics, and a postkinematic dike (~110 Ma) records the end stages of slip. The cessation of slip coincided with cooling below~180°C at~116-99 Ma as arc magmatism migrated eastward and geothermal gradients relaxed, coeval with a major reorganization in plate motion and the onset of seafloor spreading in the south Atlantic.

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Section: Geologic Backgroundmentioning

confidence: 99%

The Relationship Between Magmatism and Deformation Along the Intra‐arc Strike‐Slip Atacama Fault System, Northern Chile

et al. 2020

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“…Most of these deposits are spatially associated with the Atacama Fault System (Veloso et al, 2015), and are characterized by large sub-vertical magnetite-actinolite-apatite bodies with minor sulfides, mainly pyrite ± chalcopyrite (Ruiz et al, 1965;Bookstrom, 1977;Sillitoe, 2003). Several IOA deposits have been mined in the past (e.g., El Algarrobo, El Romeral, El Tofo, Carmen) and a few are still under production (Los Colorados, Cerro Negro Norte).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Unraveling the origin of the Andean IOCG clan: A Re-Os isotope approach

Barra

Reich

Selby

et al. 2017

Ore Geology Reviews

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'Unraveling the origin of the Andean IOCG clan : a Re-Os isotope approach.', Ore geology reviews., 81 (Part 1). pp. 62-78. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T Chilean IOCGs is the result of different events with metals derived from diverse sources i.e., the magmatic-hydrothermal system and basement/host rocks. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTRhenium and Os concentrations for the various studied deposits vary over a wide range of values at the ppb and ppt level, respectively, with many sulfides and magnetite bearing appreciable no common Os. The Re and Os contents in sulfides (pyrite, IOCGs in China and Australia argue for the involvement of a much more radiogenic crustal source possibly related to non-magmatic oxidized saline brines that leached basement rocks. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTWe conclude that Andean IOCG (and IOA) deposits in northern Chile were formed mainly by magmatic-hydrothermal processes related to the formation and emplacement of plutonic rocks with moderate contribution from leaching of basement and/or volcanic host rocks. Surface or basin-derived brines as well as sediments appear to play only a minor role in the formation of the Chilean IOCG clan.

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“…Mapped relationships in the Jurassic La Negra Formation suggest that slip on NW striking sinistral faults near Cifuncho ceased in the Late Jurassic (Contreras et al, 2013). NW striking faults near Antofagasta are well documented as secondary faults that splay from and developed contemporaneously with AFS fault strands in a transtensional duplex arrangement (Cembrano et al, 2005;Jensen et al, 2011;Veloso et al, 2015). Northwest striking faults in the Precordillera have well-documented sinistral offset in the Eocene; however, an along-strike connection of these faults to the Taltal fault has been hypothesized but not demonstrated (Abels & Bischoff, 1999).…”

Section: Introductionmentioning

confidence: 99%

Timing, Kinematics, and Displacement of the Taltal Fault System, Northern Chile: Implications for the Cretaceous Tectonic Evolution of the Andean Margin

et al. 2020

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An extensive system of NW striking faults constitutes a major tectonic feature of the Coastal Cordillera in northern Chile, but fundamental questions remain about timing and kinematics of these structures. We present new geologic mapping and geochronology that provide insight into the structural evolution and tectonic significance of the Taltal fault system (TFS). The TFS displaces the Early Cretaceous arc-parallel Atacama fault system (AFS) with~10.6 km cumulative offset across a~15 km wide zone. Brittle fault data demonstrate that the TFS is vertical to steeply NE dipping with an average sinistral slip vector plunging 11°from the NW, compatible with E-W shortening. Two late Early Cretaceous dikes cut the AFS but are cut by TFS faults, and synkinematic calcite on a TFS strand yielded a U-Pb calcite date of 114.1 ± 7.0 Ma. These data demonstrate that the AFS was abandoned and deformation (re) initiated on the TFS between~114-107 Ma, with continued slip after intrusion of the Tropezón (~110 Ma) and Librillo (106-101 Ma) plutonic complexes. Emplacement of a~146 Ma rhyolite dike along the main Taltal fault and 141 ± 11 Ma calcite mineralization in the fault core suggests that a precursor structure influenced magma emplacement and fluid flow in the Late Jurassic/Early Cretaceous, supporting the hypothesis that the TFS reactivated long-lived inherited crustal weaknesses. The Early Cretaceous shift from arc-parallel shear to slip on the TFS and E-W shortening shortly preceded migration of the magmatic arc and records a change in the Chilean margin subduction dynamics.

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Stress fields recorded on large-scale strike-slip fault systems: Effects on the tectonic evolution of crustal slivers during oblique subduction

Cited by 38 publications

References 49 publications

The Relationship Between Magmatism and Deformation Along the Intra‐arc Strike‐Slip Atacama Fault System, Northern Chile

The Relationship Between Magmatism and Deformation Along the Intra‐arc Strike‐Slip Atacama Fault System, Northern Chile

Unraveling the origin of the Andean IOCG clan: A Re-Os isotope approach

Timing, Kinematics, and Displacement of the Taltal Fault System, Northern Chile: Implications for the Cretaceous Tectonic Evolution of the Andean Margin

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