Foreland uplift during flat subduction: Insights from the Peruvian Andes and Fitzcarrald Arch

Bishop, Brandon T.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Long, Maureen D.; Tavera, Hernando

doi:10.1016/j.tecto.2018.03.005

Cited by 20 publications

(13 citation statements)

References 69 publications

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“…Finally, Hu and Liu (2016) propose a slab tear as a possible cause for the observed absence in seismicity along the projected Nazca Ridge track based on geodynamic modeling and patterns of volcanism. However, given the clear evidence from seismic imaging for a continuous slab in this region from receiver functions (i.e., Bishop et al, 2017Bishop et al, , 2018, teleseismic tomography (Scire et al, 2015), and surface wave tomography (Antonijevic et al, 2015(Antonijevic et al, , 2016, this explanation for the observed seismic gap is inconsistent with existing detailed imaging of the region.…”

Section: Nazca Ridge Seismicity Patterns Within the Peruvian Flat Slabmentioning

confidence: 80%

Effects of Oceanic Crustal Thickness on Intermediate Depth Seismicity

et al. 2020

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The occurrence of intermediate depth seismicity (70-300 km) is commonly attributed to the dehydration of hydrous phases within the downgoing oceanic plate. While some water is incorporated into the oceanic crust at formation, a significant amount of water is introduced into the plate immediately before subduction along outer-rise faults. These faults have been shown to extend to depths of over 30 km and can channel water to depths of 20 km or more beneath the seafloor. However, the amount of water introduced into the oceanic mantle lithosphere, and the role of that water in the formation of intermediate depth seismicity, has been the topic of ongoing research.Here we compile evidence from areas where the subducted oceanic crust is likely thicker than the penetration depth of water into the downgoing plate. These regions comprise aseismic plateaus and ridges (hot spot tracks) that can be compared directly to adjacent segments of the oceanic plate where oceanic crust of normal thickness is subducted. Regions with thick oceanic crust show little to no seismicity at intermediate depths, whereas adjacent regions with normal oceanic crust (∼6-8 km thick) have significant seismicity at similar depths and distances from the trench. We hypothesize that intermediate depth earthquakes observed in regions with thinner oceanic crust are caused by mantle dehydration reactions that are not possible in regions where the oceanic mantle was never hydrated because the thickness of the oceanic crust exceeded the penetration depth of water into the plate. We compare our observations to phase diagrams of hydrous basalt and hydrated depleted peridotite to determine pressures and temperatures that would be consistent with our observations. These can provide valuable constraints, not only on the degree of hydration and dehydration in the downgoing plate, but also as ground-truth for thermal models of these regions, all of which have complex, three-dimensional, time-variant subduction geometries and thermal histories.

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Section: Nazca Ridge Seismicity Patterns Within the Peruvian Flat Slabmentioning

confidence: 80%

Effects of Oceanic Crustal Thickness on Intermediate Depth Seismicity

et al. 2020

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“…This is dominant over oceanic subducting plate convergence as demonstrated in the Central Andes, where an increase in deformation occurred during stages of convergence rate decrease (Oncken et al, 2006). Slab shallowing is recognized to produce significant foreland uplift, as is observed along the present day flat-slab in central Chile (Ramos et al, 2002) and Peru (Bishop et al, 2018). Examples in the geological record include the Late Cretaceous to early Eocene, low-angle subduction in the Laramide orogen, USA (Jordán et al, 1983;Fan and Carrapa, 2014) and Paleocene low-angle subduction in Alaska, USA (Finzel et al, 2011).…”

Section: Discussionmentioning

confidence: 94%

The role of slab geometry in the exhumation of cordilleran-type orogens and their forelands: Insights from northern Patagonia

et al. 2021

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In cordilleran-type orogens, subduction geometry exerts a fundamental control on the tectonic behavior of the overriding plate. An integrated low-temperature, large thermochronological data set is used in this study to investigate the burial and exhumation history of the overriding plate in northern Patagonia (40°−45°S). Thermal inverse modeling allowed us to establish that a ∼2.5−4-km-thick section originally overlaid the Jurassic−Lower Cretaceous successions deposited in half-graben systems that are presently exposed in the foreland. Removal of the sedimentary cover started in the late Early Cretaceous. This was coeval with an increase of the convergence rate and a switch to a westward absolute motion of the South American Plate that was accompanied by shallowing of the subducting slab. Unroofing was probably further enhanced by Late Cretaceous to early Paleogene opening of a slab window beneath the overriding plate. Following a tectonically quiescent period, renewed exhumation occurred in the orogen during relatively fast Neogene plate convergence. However, even the highly sensitive apatite (U-Th)/He thermochronometer does not record any coeval cooling in the foreland. The comparison between Late Cretaceous and Neogene exhumation patterns provides clear evidence of the fundamental role played by inter-plate coupling associated with shallow slab configurations in controlling plate-scale deformation. Our results, besides highlighting for the first time how the whole northern Patagonia foreland was affected by an exhumation of several kilometers since the Late Cretaceous, provide unrivalled evidence of the link between deep geodynamic processes affecting the slab and the modes and timing of unroofing of different sectors of the overriding plate.

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“…This indicates a fundamental change in the geodynamic mechanism of subsidence after initial emplacement of the Wasatch anticlinorium. Possible explanations include (1) movement on the Crawford, Absaroka, and Hogsback thrusts provided insufficient topographic loading to produce flexure; (2) erosional unloading of thrust‐belt topography resulted in unconformity development in the wedgetop and proximal foredeep depozones (Heller et al, 1988; Sinclair et al, 1991); or, more likely, (3) that topographic loading was compensated at depth, possibly due to uplift associated with flat subduction (Bishop et al, 2018; Dávila & Lithgow‐Bertelloni, 2015; Flament et al, 2015) as previously suggested for Uinta Basin (Bartschi et al, 2018; Kendall et al, 2019). A possible exception is the Crazy Mountain Basin in southwestern Montana, which preserves stratal thickening adjacent to the thrust belt (Figure 3c).…”

Section: Discussionmentioning

confidence: 99%

Laramide Orogenesis Driven by Late Cretaceous Weakening of the North American Lithosphere

et al. 2020

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This paper investigates the causes of the Late Cretaceous transition from “Sevier” to “Laramide” orogenesis and the spatial and temporal evolution of effective elastic thickness (EET) of the North American lithosphere. We use a Monte Carlo flexural model applied to 34 stratigraphic profiles in the Laramide province and five profiles from the Western Canadian Basin to estimate model parameters which produce flexural profiles that match observed sedimentary thicknesses. Sediment thicknesses come from basins from New Mexico to Canada of Cenomanian–Eocene age that are related to both Sevier and Laramide crustal loads. Flexural models reveal an east‐to‐west spatial decrease in EET in all time intervals analyzed. This spatial decrease in EET may have been associated with either bending stresses associated with the Sevier thrust belt, or increased proximity to attenuated continental crust at the paleocontinental margin. In the Laramide province (i.e., south of ~48°N) there was a coeval, regional decrease in EET between the Cenomanian–Santonian (~98–84 Ma) and the Campanian–Maastrichtian (~77–66 Ma), followed by a minor decrease between the Maastrichtian and Paleogene. However, there was no decrease in EET in the Western Canada Basin (north of ~48°N), which is consistent with a lack of Laramide‐style deformation or flat subduction. We conclude that the regional lithospheric weakening in the late Santonian–Campanian is best explained by hydration of the North American lithosphere thinned by bulldozing by a shallowly subducting Farallon plate. The weakening of the lithosphere facilitated Laramide contractional deformation by focusing end‐loading stresses associated with flat subduction. Laramide deformation in turn may have further reduced EET by weakening the upper crust. Finally, estimates of Campanian–Maastrichtian and Paleogene EET are comparable to current estimates indicating that the modern distribution of lithospheric strength was achieved by the Campanian in response to flat subduction.

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Foreland uplift during flat subduction: Insights from the Peruvian Andes and Fitzcarrald Arch

Cited by 20 publications

References 69 publications

Effects of Oceanic Crustal Thickness on Intermediate Depth Seismicity

Effects of Oceanic Crustal Thickness on Intermediate Depth Seismicity

The role of slab geometry in the exhumation of cordilleran-type orogens and their forelands: Insights from northern Patagonia

Laramide Orogenesis Driven by Late Cretaceous Weakening of the North American Lithosphere

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