The Late Paleogene to Neogene Volcanic Arc in the Southern Central Andes (28°–37° S)

Litvak, Vanesa D.; Poma, Stella; Jones, Rebecca; Paz, Lucía Fernández; Iannelli, Sofía B.; Spagnuolo, M. G.; Kirstein, Linda A.; Folguera, Andrés; Ramos, Víctor A.

doi:10.1007/978-3-319-67774-3_20

Cited by 15 publications

(13 citation statements)

References 61 publications

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“…Foreland quiescence marks a ~20 Myr pause in retroarc shortening and is synchronous with upper crustal extension within the thrust belt and broader magmatic arc (Principal Cordillera), as recorded by late middle Eocene‐early Miocene growth of the Loncopué, Cura‐Mallín, and Abanico extensional basins (Burns et al, ; Charrier et al, , ; Folguera et al, ; Godoy et al, ; Jordan et al, ; Ramos & Folguera, ; Rojas Vera et al, , ). This sustained period with no significant retroarc shortening and broad intraorogenic extension appears to have affected much of the transitional zone from the central to southern Andes, from at least 28°S to 40°S (Charrier et al, ; Jordan et al, ; Litvak et al, , ; Winocur et al, ). At this time, the magmatic arc remained relative fixed or possibly retreated westward to the Principal Cordillera/Central Valley boundary (Charrier et al, ).…”

Section: Central To Southern Andes Transition (35°s)mentioning

confidence: 99%

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

2018

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Construction of the Andes has been governed largely by fluctuating contractional, neutral, and extensional tectonic regimes during differing degrees of mechanical coupling along the convergent plate boundary. These three contrasting regimes are likely regulated by geodynamic variations in absolute trenchward motion of South America and episodic regional shifts in the geometry of the subducting oceanic slab. Alternations among these three modes are revealed in syntheses of Mesozoic‐Cenozoic crustal deformation, basin evolution, and arc magmatism along orogen‐perpendicular transects across the central and southern Andes at 23°S, 35°S, and 43°S. Despite considerable along‐strike dissimilarities in the magnitude of deformation, a comparable tectonic regime typified the early Andean history, as defined by a transition from Late Jurassic‐Early Cretaceous postrift thermal subsidence to Late Cretaceous retroarc shortening. A key contradiction is expressed for the late middle Eocene to earliest Miocene, when neutral to extensional conditions affected retroarc to forearc regions, except in parts of the central Andes, which experienced retroarc shortening with only localized forearc extension. This mixed‐mode scenario during Paleogene time may reflect decoupling along the plate boundary (possibly during slab rollback within a retreating subduction system) in which widespread stasis or low‐magnitude extension dominated the southern Andes but was inhibited in the strongly shortened central Andes at 15–25°S where shallow subduction and/or high topography boosted plate coupling. Comparable temporal and spatial shifts in tectonic regime along the Andes and other convergent margins can be related to variable degrees of coupling during first‐order plate‐scale changes in convergence and second‐order regional cycles of slab shallowing and steepening.

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Section: Central To Southern Andes Transition (35°s)mentioning

confidence: 99%

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

2018

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“…Red to yellow indicates the change from thin to thick-skinned foreland deformation (Ramos et al, 2002). Rotation symbols indicate crustal rotation based on paleomagnetic data (Japas et al, 2016), red triangles indicate volcanic events events (Trumbull et al, 2006;Litvak et al, 2018;Quiero et al, 2022). S1, S2, S3 hold for identified stages of propagation of the deformation to the east.…”

Section: Regional Setting Of the Southern Central Andesmentioning

confidence: 99%

Flat-slab conveyor effect induces precursory crustal contraction in the Central Andes

Pons

Piceda

Sobolev

et al. 2023

Preprint

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The southern Central Andes (29°S-39°S) is a key area to better understand the mechanisms of non-collisional mountain building associated with changes in oceanic plate dip geometry and the interaction between the oceanic and continental plates. The orogen experienced an increase of shortening during the last 35 Ma which is coeval with the southward migration of a flat subduction segment and the passage of a bathymetric anomaly known as the Juan Fernandez Ridge. Based on data-driven geodynamic numerical modelling, we use the present-day plate configuration to assess the role of the flat-slab on the deformation of the overriding plate. The resulting deformation field suggests that the shallowing of the oceanic slab controlled the onset of the compression at ~10 Ma before the arrival of the ridge leading to the formation of a ~370-km-wide transpressive shear zone at the transition between the flat (27°S - 32°S) and the steep slab segments (south of 33°S). The contraction of the crust is accommodated by the dextral rotation of micro-crustal Sierras Pampeanas basement blocks and strike-slip deformation at their borders (i.e., thick-skin foreland deformation). We propose a novel concept for oceanic and continental plate interaction, where the southward migration of the flat slab functions as a conveyor belt for upper-plate crustal deformation, with an increase in the intensity of deformation foreshadowing the flat-slab arrival.

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“…8F and 9A; Kay and Mpodozis, 2002;Jones et al, 2016). Oligocene volcanic rocks yielded geochemical signatures characteristic of partial melting of mantle wedge material (Kay and Abbruzzi, 1996;Jones et al, 2016;Litvak et al, 2018) and were associated with intra-arc oblique faulting (Piquer et al, 2017;Mosolf et al, 2019;Mackaman-Lofland et al, 2019). Middle Miocene arc volcanism was defined by isotopic signatures indicative of crustal thickening (>50 km; Kay et al, 1991;Jones et al, 2015).…”

Section: Oligocene-pliocenementioning

confidence: 99%

Detrital zircon record of Phanerozoic magmatism in the southern Central Andes

et al. 2021

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The spatial and temporal distribution of arc magmatism and associated isotopic variations provide insights into the Phanerozoic history of the western margin of South America during major shifts in Andean and pre-Andean plate interactions. We integrated detrital zircon U-Th-Pb and Hf isotopic results across continental magmatic arc systems of Chile and western Argentina (28°S–33°S) with igneous bedrock geochronologic and zircon Hf isotope results to define isotopic signatures linked to changes in continental margin processes. Key tectonic phases included: Paleozoic terrane accretion and Carboniferous subduction initiation during Gondwanide orogenesis, Permian–Triassic extensional collapse, Jurassic–Paleogene continental arc magmatism, and Neogene flat slab subduction during Andean shortening. The ~550 m.y. record of magmatic activity records spatial trends in magma composition associated with terrane boundaries. East of 69°W, radiogenic isotopic signatures indicate reworked continental lithosphere with enriched (evolved) εHf values and low (<0.65) zircon Th/U ratios during phases of early Paleozoic and Miocene shortening and lithospheric thickening. In contrast, the magmatic record west of 69°W displays depleted (juvenile) εHf values and high (>0.7) zircon Th/U values consistent with increased asthenospheric contributions during lithospheric thinning. Spatial constraints on Mesozoic to Cenozoic arc width provide a rough approximation of relative subduction angle, such that an increase in arc width reflects shallower slab dip. Comparisons among slab dip calculations with time-averaged εHf and Th/U zircon results exhibit a clear trend of decreasing (enriched) magma compositions with increasing arc width and decreasing slab dip. Collectively, these data sets demonstrate the influence of subduction angle on the position of upper-plate magmatism (including inboard arc advance and outboard arc retreat), changes in isotopic signatures, and overall composition of crustal and mantle material along the western edge of South America.

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The Late Paleogene to Neogene Volcanic Arc in the Southern Central Andes (28°–37° S)

Cited by 15 publications

References 61 publications

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

Flat-slab conveyor effect induces precursory crustal contraction in the Central Andes

Detrital zircon record of Phanerozoic magmatism in the southern Central Andes

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