Plume overriding triggers shallow subduction and orogeny in the southern Central Andes

Gianni, Guido M.; García, Héctor; Lupari, Marianela; Pesce, Agustina; Folguera, Andrés

doi:10.1016/j.gr.2017.06.011

Cited by 29 publications

(12 citation statements)

References 65 publications

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“…While horizontal oceanic slab-tearing is expected after continental collision 4 , vertical slab tearing is detected in convergent settings that undergo non-uniform slab retreat 2 or in zones at the edges of active margins accommodating trenchward slab motion 1 . In addition, vertical tearing is locally observed where aseismic ridges 5 , mantle plumes 6,7 or oceanic fracture zones interact with active margins 8 .…”

Section: Introductionmentioning

confidence: 99%

Surface and mantle records reveal an ancient slab tear beneath Gondwana

Gianni

Navarrete

Spagnotto

2019

Sci Rep

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Vertical slab-tearing has been widely reported in modern convergent settings profoundly influencing subduction and mantle dynamics. However, evaluating a similar impact in ancient convergent settings, where oceanic plates have been subducted and the geological record is limited, remains challenging. In this study, we correlate the lower mantle structure, which retained the past subduction configuration, with the upper-plate geological record to show a deep slab rupture interpreted as a large-scale tearing event in the early Mesozoic beneath southwestern Gondwana. For this purpose, we integrated geochronological and geological datasets with P-wave global seismic tomography and plate-kinematic reconstructions. The development of a Late Triassic-Early Jurassic slab-tearing episode supports (i) a slab gap at lower mantle depths, (ii) a contrasting spatiotemporal magmatic evolution, (iii) a lull in arc activity, and (iv) intraplate extension and magmatism in the Neuquén and Colorado basins. This finding not only has implications for identifying past examples of a fundamental process that shapes subduction zones, but also illustrates an additional mechanism to trigger slab-tearing in which plate rupture is caused by opposite rotation of slab segments.

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Section: Introductionmentioning

confidence: 99%

Surface and mantle records reveal an ancient slab tear beneath Gondwana

Gianni

Navarrete

Spagnotto

2019

Sci Rep

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“…Sources associated with this anomalous retroarc magmatism were envisaged in the last years through considerable amounts of geophysical and geochemical data (Burd et al, ; Pesicek et al, ; Richarte et al, ; Søager et al, , ), recognizing seismic and conductive anomalies corresponding to enriched mantle sources that fed the volcanic plateau. These were visualized as a complex plume head related to a slab tearing of the Nazca plate (Figure ; Gianni et al, ; Pesicek et al, ), branched into a series of smaller magmatic bodies impacting and storage beneath the southern Payenia Volcanic Province, such as the Auca Mahuida, Tromen, Los Volcanes, and Payun Matru volcanic fields (Burd et al, ; Figure ).…”

Section: Introductionmentioning

confidence: 99%

Crustal and Mantle Structure Beneath the Southern Payenia Volcanic Province Using Gravity and Magnetic Data

et al. 2019

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The Auca Mahuida volcanic field lies on the southernmost Payenia Volcanic Province, one of the broadest retroarc volcanic plateaux in the southern Central Andes (~38°S). This voluminous basaltic flooding of Quaternary age was originated from a deep asthenospheric source, interpreted as a mantle plume product of changing slab dynamics. The geometry of this source is deduced from magnetotelluric data, but the limited spatial coverage of this array does not allow a detailed resolution of this anomaly. In order to present a detailed geometry of the conductive anomaly and related crustal magmatic bodies, we used multiple data sources. We combined Magnetic and Bouguer anomalies, Curie isotherm depth (T c ), Elastic Thickness (T e ) and Moho depth derived from the Global Earth Magnetic Anomaly Grid (EMAG2) and terrestrial gravity measurements, all together in a holistic geophysical analysis. The magnetic data depict a nearly 200-km-in-diameter circular anomaly that would correspond to a dense body according to the Bouguer anomaly. Geoid data from the Gravity Field Model (EIGEN-6c4) have been filtered in order to isolate deeper mass influences and visualize the asthenospheric upwelling previously described from magnetotelluric data. Moho inversion yields a crustal attenuation at 36-to 32-km depth coinciding with T e below 20-km depth and a shallow T c (≤15-km depth) at the site where Geoid positive undulation was calculated. Finally, surface analysis allowed defining a topographic swell, compatible with the dimensions of the identified magnetic anomaly, where the main rivers deviated, potentially due to a recent base level change.Sources associated with this anomalous retroarc magmatism were envisaged in the last years through considerable amounts of geophysical and geochemical data (Burd et al., 2014; Pesicek et al., 2012; Richarte ASTORT ET AL.

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“…The two contractional stages that took place in the Southern Central Andes, in Late Cretaceous-Eocene and Miocene times, acted in concert with significant eastward arc expansions which have been interpreted in terms of the shallowing of the subducted plate (Ramos and Folguera, 2005;Kay and Copeland, 2006). Particularly, the youngest arc expansion has been recently related to subduction of the Payenia mantle plume in Neogene times, which is currently impacting the Andean back arc region to the east of the study area (Gianni et al, 2017). This process would have ended in Pliocene times with a slab detachment and steepening of the subducting Nazca plate (Pesicek et al, 2012), the development of extension in the hinterland region of the Andes (Folguera et al, 2006;Rojas Vera et al, 2014) and contraction in the Andean foothills (e. g. Galland et al, 2007;Messager et al, 2010).…”

Section: Geologic Settingmentioning

confidence: 97%

Magnetic characterization of a retroarc extensional basin: The Loncopué Trough

Pesce

Giménez

Gianni

et al. 2019

Journal of South American Earth Sciences

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The Loncopué Trough is a Pliocene to Quaternary extensional basin developed over the hinterland area of the Southern Central Andes. This basin is bounded by two neotectonic extensional fault systems delimiting a narrow topographic low. Previous studies have mostly focused on structural and geochemical aspects of this feature. However, geophysical surveys, aimed to unravel deep structure beneath a thick-younger than 5 My volcanic coverage, are scarce and based their interpretations on low resolution data sets. In this study, we collected new aeromagnetic data with the objective of characterizing the magnetic properties of the crust in the Loncopué Through and nearby zones. Additionally, we analyze the spatial relation between geological structures, volcanic fields and magnetic data. In order to highlight the boundaries of the magnetic sources and calculate the basement depth, we applied derivative techniques and the source parameter imaging. Also, we estimated an effective susceptibility model using the Magnetization Vector Inversion method, which takes into account the combined effects of remanence and induced magnetization. To determine the thermal structure of the area, we calculated the Curie depth points through the spectral analysis technique. From the analysis of magnetic data we were able to characterize the main structures and lineaments associated with this retroarc extensional trough. Notably, only the Loncopué eastern fault system seems to be a crustal-scale tectonic feature, while E-W-, ENE-and ESE-trending lineaments are interpreted as relatively minor structures segmenting the basement. Finally, our susceptibility model, together with the analysis of the Curie point, revealed potential magmatic/hydrothermal reservoirs in the Copahue volcano, and the Codihue and Cajón de Almanza regions that could be connected at depth forming a regional magmatic body.

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Plume overriding triggers shallow subduction and orogeny in the southern Central Andes

Cited by 29 publications

References 65 publications

Surface and mantle records reveal an ancient slab tear beneath Gondwana

Surface and mantle records reveal an ancient slab tear beneath Gondwana

Crustal and Mantle Structure Beneath the Southern Payenia Volcanic Province Using Gravity and Magnetic Data

Magnetic characterization of a retroarc extensional basin: The Loncopué Trough

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