Thermal and lithospheric structure of the Chilean-Pampean flat-slab from gravity and magnetic data

Sánchez, Mabel; García, Héctor; Acosta, Gemma; Gianni, Guido M.; González, Marcelo; Ariza, Juan P.; Martinez, María Alejandra; Folguera, Andrés

doi:10.1016/b978-0-12-816009-1.00005-8

Cited by 6 publications

(9 citation statements)

References 69 publications

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“…Although a complex thermal structure is inferred for this region (Sánchez et al 2019) and some discrepancies exist regarding the associated thermal regime during the transition from normal to flat subduction (see Collo et al, 2011 andGoddard andCarrapa, 2018), the cooling of the thermal regime by 8 Myrs implied by our models is consistent with the inferred low heat flow in the region based on borehole, seismic, thermochronological and magnetic data (Marot et al, 2014;Collo et al, 2018;Sánchez et al 2019) et al, 1991, Gutscher 2002, Manea and Manea 2011.…”

Section: E) Regional Geodynamic Contextsupporting

confidence: 85%

Linking thermochronological data to transient geodynamic regimes; new insights from kinematic modeling and Monte Carlo sampling of thermal boundary conditions

Francisco

Gallagher

Ezpeleta

et al. 2021

Journal of South American Earth Sciences

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Section: E) Regional Geodynamic Contextsupporting

confidence: 85%

Linking thermochronological data to transient geodynamic regimes; new insights from kinematic modeling and Monte Carlo sampling of thermal boundary conditions

Francisco

Gallagher

Ezpeleta

et al. 2021

Journal of South American Earth Sciences

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“…Along 𝐴𝐴 30 • S, Heit et al (2008) detected a strong oceanic LAB signal west of 𝐴𝐴 69 • W that suddenly disappears and even changes polarity further east below the slab tearing zone (Figure 3b). Recent magnetic and gravity modeling work (Sánchez et al, 2019) also inferred hot asthenospheric flow beneath the flat slab and local slab thinning. These observations support our interpretation of M1 and M2 as evidence for thinning and tearing of the slab (Figure 4).…”

Section: Slab Thinning and Tearing Along The Juan Fernandez Ridgementioning

confidence: 98%

Impact of the Juan Fernandez Ridge on the Pampean Flat Subduction Inferred From Full Waveform Inversion

Gao

Yuan

Heit

et al. 2021

Geophysical Research Letters

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“…Heit et al (2008) detected a strong oceanic LAB signal west of 𝐴𝐴 69 • W that suddenly disappears and even changes polarity further east below the slab tearing zone (Figure 3b). Recent magnetic and gravity modeling work (Sánchez et al, 2019) also inferred hot asthenospheric flow beneath the flat slab and local slab thinning. These observations support our interpretation of M1 and M2 as evidence for thinning and tearing of the slab (Figure 4).…”

Section: Slab Thinning and Tearing Along The Juan Fernandez Ridgementioning

confidence: 98%

“…Two prominent flat subduction segments beneath the Andes are the Peruvian and Pampean flat subduction zones, north and south of the conspicuous kink in the South American coastline, respectively. They have been documented based on seismology (e.g., Pesicek et al, 2012;Wagner et al, 2005), volcanism (e.g., Kay & Abbruzzi, 1996;Kay & Mpodozis, 2002), gravity modeling (e.g., Sánchez et al, 2019) and electrical conductivity measurements (e.g., Burd et al, 2013Burd et al, , 2014. In this study, we focus on the Pampean flat subduction and Payenia steep subduction to the south, from 𝐴𝐴 28 • -𝐴𝐴 38 • S (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Impact of the Juan Fernandez ridge on the Pampean flat subduction inferred from full waveform inversion

Gao

Yuan

Heit

et al. 2021

Preprint

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A new seismic model for crust and upper mantle of the south Central Andes is derived from full waveform inversion, covering the Pampean flat subduction and adjacent Payenia steep subduction segments. Focused crustal low-velocity anomalies indicate partial melts in the Payenia segment along the volcanic arc, whereas weaker low-velocity anomalies covering a wide zone in the Pampean segment are interpreted as remnant partial melts. Thinning and tearing of the flat Nazca slab is inferred from gaps in the slab along the inland projection of the Juan Fernandez Ridge. A high-velocity anomaly in the mantle below the flat slab is interpreted as relic Nazca slab segment, which indicates an earlier slab break-off triggered by the buoyancy of the Juan Fernandez Ridge during the flattening process. In Payenia, largescale low-velocity anomalies atop and below the re-steepened Nazca slab are associated with the reopening of the mantle wedge and sub-slab asthenospheric flow, respectively. Plain Language SummaryTaking advantage of the abundant information recorded in seismic waveforms, we imaged the seismic structure of the crust and upper mantle beneath central Chile and western Argentina, where the oceanic Nazca slab is subducting beneath the South American plate. The subducted Nazca slab is almost flat at a depth of 100-150 km in the north of the study area below the Pampean region, where the Juan Fernandez seamount ridge is subducting as part of the Nazca slab. The slab steepens again in the south in the Payenia region. Our model reveals pronounced low-velocity anomalies within the Pampean flat slab along the inland projection of the Juan Fernandez Ridge, indicating that the Pampean flat slab is thinned or even torn apart. A high-velocity anomaly is imaged beneath the flat slab, representing a former slab segment that was broken off during the slab flattening process and was overridden by the advancing young slab. Our model suggests a causal relationship between the oceanic ridge subduction and the flat slab formation. In the Payenia region, the slab resteepening resulted in the re-establishment of the mantle wedge and induced hot mantle flow below the slab, which are characterized by low-velocity anomalies in the model.

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Thermal and lithospheric structure of the Chilean-Pampean flat-slab from gravity and magnetic data

Cited by 6 publications

References 69 publications

Linking thermochronological data to transient geodynamic regimes; new insights from kinematic modeling and Monte Carlo sampling of thermal boundary conditions

Linking thermochronological data to transient geodynamic regimes; new insights from kinematic modeling and Monte Carlo sampling of thermal boundary conditions

Impact of the Juan Fernandez Ridge on the Pampean Flat Subduction Inferred From Full Waveform Inversion

Impact of the Juan Fernandez ridge on the Pampean flat subduction inferred from full waveform inversion

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