The role of strain localization in magma injection into a transtensional shear zone (Variscan belt, SW Iberia)

Pereira, M. Francisco; Chichorro, M.; Fernández, Carlos; Silva, J. B.; Matias, Filipa Vieira

doi:10.1144/jgs2012-008

Cited by 9 publications

(6 citation statements)

References 38 publications

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“…The high-T/low-P deformation affected syn-orogenic granitoids (peraluminous granodiorite-granite suite) and previous folds, and was parted into subhorizontal and strike-slip shear zones parallel or subparallel to the structural trend of the orogen (Díaz Azpiroz et al, 2004;Pereira et al, 2009Pereira et al, , 2012bPereira et al, , 2013. On the other hand, the Iberian Allochthon displays a number of low-angle normal faults that cut previous faults and folds (Azor et al, 1994b;Expósito et al, 2002).…”

Section: Sw Iberian Allochthon and Autochthonmentioning

confidence: 99%

Tectonic evolution of Variscan Iberia: Gondwana–Laurussia collision revisited

Fernández

Arenas

Pereira

et al. 2016

Earth-Science Reviews

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109

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An integrated interpretation of the late Paleozoic structural and geochronological record of the Iberian Massif is presented and discussed under the perspective of a Gondwana-Laurussia collision giving way to the Variscan orogen. Compressional and extensional structures developed during the building of the Variscan orogenic crust of Iberia are linked together into major tectonic events operating at lithosphere scale. A review of the tectonometamorphic and magmatic evolution of the Iberian Massif reveals backs and forths in the overall convergence between Gondwana and Laurussia during the amalgamation of Pangea in late Paleozoic times. Stages dominated by lithosphere compression are characterized by subduction, both oceanic and continental, development of magmatic arcs, (over-and under-) thrusting of continental lithosphere, and folding. Variscan convergence resulted in the eventual transference of a large allochthonous set of peri-Gondwanan terranes, the Iberian Allochthon, onto the Gondwana mainland. The Iberian Allochthon bears the imprint of previous interaction between Gondwana and Laurussia, including their juxtaposition after the closure of the Rheic Ocean in Lower Devonian times. Stages governed by lithosphere extension are featured by the opening of two short-lived oceanic basins that dissected previous Variscan orogenic crust, first in the Lower-Middle Devonian, following the closure of the Rheic Ocean, and then in the early Carboniferous, following the emplacement of the peri-Gondwanan allochthon. An additional, major intra-orogenic extensional event in the early-middle Carboniferous dismembered the Iberian Allochthon into individual thrust stacks separated by extensional faults and domes. Lateral tectonics played an important role through the Variscan orogenesis, especially during the creation of new tectonic blocks separated by intracontinental strike-slip shear zones in the late stages of continental convergence. Units, (6) Upper Allochthonous Units, (7) Beja-Acebuches Ophiolite, and (8) South Portuguese Zone. Gathering of 4, 5, and 6 will be also referred to as Iberian Allochthon (or simply Allochthon). A simple restoration of the cross-section shown in Figure 3 (Fig. 4a) reveals two major suture zones featured with ophiolitic units with different protolith ages. The NNE-dipping suture represented by the Beja-Acebuches Ophiolite (Bard and Moine, 1979; Munhá et al., 1986; Quesada et al., 1994) cuts the suture marked by the Allochthonous Ophiolitic Units (Arenas et al., 1986) and divides the Iberian Massif in two major blocks. The northern block comprises the Cantabrian Zone, and the Iberian Autochthon, Parautochthon and Allochthon, all of which have Gondwanan affinity

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Section: Sw Iberian Allochthon and Autochthonmentioning

confidence: 99%

Tectonic evolution of Variscan Iberia: Gondwana–Laurussia collision revisited

Fernández

Arenas

Pereira

et al. 2016

Earth-Science Reviews

Self Cite

109

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“…Transpressional deformation during magmatism has been proposed to be important for the mobilization of magma through the continental crust (Weinberg et al, 2004;Marcotte et al, 2005;Whitney et al, 2009;Pereira et al, 2013). Other workers, however, have suggested that changes in the thermal gradient of country rocks dominantly control magma transport (Vigneresse, 1995;Johnson, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Other workers, however, have suggested that changes in the thermal gradient of country rocks dominantly control magma transport (Vigneresse, 1995;Johnson, 2009). The interplay between pluton emplacement and transpression at different crustal levels is still poorly understood; consequently, an enhanced understanding of the way(s) in which magma is transferred and emplaced within continental arcs during periods of regional deformation can elucidate a fundamental question in the evolution of continental crust and magmatic arc systems (e.g., Paterson et al, 1998;Paterson and Schmidt, 1999;Blanquat et al, 1998;Vigneresse and Clemens, 2000;Pereira et al, 2013;Bitencourt and Nardi, 2000;Sen et al, 2014;Webber et al, 2015;Stuart et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Temporal and spatial variations in magmatism and transpression in a Cretaceous arc, Median Batholith, Fiordland, New Zealand

et al. 2019

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We investigated the interplay between deformation and pluton emplacement with the goal of providing insights into the role of transpression and arc magmatism in forming and modifying continental arc crust. We present 39 new laser-ablation–split-stream–inductively coupled plasma–mass spectrometry (LASS-ICP-MS) and secondary ion mass spectrometry (SIMS) 206Pb/238U zircon and titanite dates, together with titanite geochemistry and temperatures from the lower and middle crust of the Mesozoic Median Batholith, New Zealand, to (1) constrain the timing of Cretaceous arc magmatism in the Separation Point Suite, (2) document the timing of titanite growth in low- and high-strain deformational fabrics, and (3) link spatial and temporal patterns of lithospheric-scale transpressional shear zone development to the Cretaceous arc flare-up event. Our zircon results reveal that Separation Point Suite plutonism lasted from ca. 129 Ma to ca. 110 Ma in the middle crust of eastern and central Fiordland. Deformation during this time was focused into a 20-km-wide, arc-parallel zone of deformation that includes previously unreported segments of a complex shear zone that we term the Grebe shear zone. Early deformation in the Grebe shear zone involved development of low-strain fabrics with shallowly plunging mineral stretching lineations from ca. 129 to 125 Ma. Titanites in these rocks are euhedral, are generally aligned with weak subsolidus fabrics, and give rock-average temperatures ranging from 675 °C to 700 °C. We interpret them as relict magmatic titanites that grew prior to low-strain fabric development. In contrast, deformation from ca. 125 to 116 Ma involved movement along subvertical, mylonitic shear zones with moderately to steeply plunging mineral stretching lineations. Titanites in these shear zones are anhedral grains/aggregates that are aligned within mylonitic fabrics and have rock-average temperatures ranging from ∼610 °C to 700 °C. These titanites are most consistent with (re)crystallization in response to deformation and/or metamorphic reactions during amphibolite-facies metamorphism. At the orogen scale, spatial and temporal patterns indicate that the Separation Point Suite flare-up commenced during low-strain deformation in the middle crust (ca. 129–125 Ma) and peaked during high-strain, transpressional deformation (ca. 125–116 Ma), during which time the magmatic arc axis widened to 70 km or more. We suggest that transpressional deformation during the arc flare-up event was an important process in linking melt storage regions and controlling the distribution and geometry of plutons at mid-crustal levels.

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“…3-7, 9 and 12), following several previous studies that have proposed that high-strain zones (shear and tension zones) could play a significant role in the draining of residual fluids from deeper retention zones at the strain rate of 10 −15 s −1 to ∼10 −10 s −1 indicated by structure (Fernández and Castro, 1999), analogue (Benn et al, 1998) and numerical models (Cruden, 1998;Berdiel et al, 1997), feeding the upper crust with partially molten lower crustal rocks (Fossen and Tikoff, 1998;Neves et al, 1996Neves et al, , 2000Pereira et al, 2013;Snoke et al, 1999;Weinberg et al, 2006).…”

Section: Strain and Reliefmentioning

confidence: 91%