A unified three-dimensional model of the lithospheric structure at the subduction corner in southeast Alaska: Summary results from STEEP

Pavlis, Gary L.; Bauer, Mark A.; Elliott, Julie; Koons, P. O.; Pavlis, Terry L.; Ruppert, N. A.; Ward, Kevin M.; Worthington, L. L.

doi:10.1130/ges01488.1

Cited by 28 publications

(21 citation statements)

References 71 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The “Yakutat slab shoulder region” is a high‐speed anomaly in our model in the upper mantle, which has not been reported in previous tomography studies. Pavlis et al () suggested that Yakutat slab shoulder experienced a block rotation over the past 6 Ma.…”

Section: Discussionmentioning

confidence: 99%

A 3‐D Shear Velocity Model of the Crust and Uppermost Mantle Beneath Alaska Including Apparent Radial Anisotropy

2019

View full text Add to dashboard Cite

This paper presents a model of the 3-D shear velocity structure of the crust and uppermost mantle beneath Alaska and its surroundings on a~50-km grid, including crustal and mantle radial anisotropy, based on seismic data recorded at more than 500 broadband stations. The model derives from a Bayesian Monte Carlo inversion of Rayleigh wave group and phase speeds and Love wave phase speeds determined from ambient noise and earthquake data. Prominent features resolved in the model include the following: (1) Apparent crustal radial anisotropy is strongest across the parts of central and northern Alaska that were subjected to significant extension during the Cretaceous. This is consistent with crustal anisotropy being caused by deformationally aligned middle to lower crustal sheet silicates (micas) with shallowly dipping foliation planes beneath extensional domains. (2) Crustal thickness estimates are similar to those from receiver functions by Miller and Moresi (2018, https://doi.org/10.1785/0220180222). (3) Very thick lithosphere underlies Arctic-Alaska, with high shear wave speeds that extend at least to 120-km depth, which may challenge rotational transport models for the evolution of the region. (4) Subducting lithosphere beneath Alaska is resolved, including what we call the "Barren Islands slab anomaly," an "aseismic slab edge" north of the Denali Volcanic Gap, the "Wrangellia slab anomaly," and Yakutat lithosphere subducting seaward of the Wrangell volcanic field. (5) The geometry of the Alaskan subduction zone generally agrees with the slab model Alaska_3D 1.0 of Jadamec and Billen (2010, https://doi.org/10.1038/nature09053) except for the Yakutat "slab shoulder region," which is newly imaged in our model.

show abstract

Section: Discussionmentioning

confidence: 99%

A 3‐D Shear Velocity Model of the Crust and Uppermost Mantle Beneath Alaska Including Apparent Radial Anisotropy

2019

View full text Add to dashboard Cite

show abstract

“…The Yakutat Terrane is a smaller feature in southern central Alaska that lies south of the Denali fault zone, between the Wrangell volcanic field (WVF) and active Aleutian arc volcanism, and overlies the Wrangellia Composite and the Southern Margin Composite Terranes. The Yakutat Terrane, young oceanic crust formed off the west coast of North America, began migrating north along the Queen Charlotte/Fairweather transform in the Eocene before subducting beneath Southern Alaska at~35 Ma (Christeson et al, 2010;Finzel et al, 2011;Pavlis et al, 2019). The onset of Yakutat subduction corresponds to the start of Chugach and Alaska range uplift due to a decrease in the subduction angle of the Yakutat and Pacific plates; this is supported by the cessation of magmatism in the Denali volcanic gap (Finzel et al, 2011;Martin-Short et al, 2018).…”

Section: Tectonic Historymentioning

confidence: 96%

Shear Velocity Model of Alaska Via Joint Inversion of Rayleigh Wave Ellipticity, Phase Velocities, and Receiver Functions Across the Alaska Transportable Array

et al. 2020

Self Cite

View full text Add to dashboard Cite

Through the Alaska Transportable Array deployment of over 200 stations, we create a 3‐D tomographic model of Alaska with sensitivity ranging from the near surface (<1 km) into the upper mantle (~140 km). We perform a Markov chain Monte Carlo joint inversion of Rayleigh wave ellipticity and phase velocities, from both ambient noise and earthquake measurements, along with receiver functions to create a shear wave velocity model. We also use a follow‐up phase velocity inversion to resolve interstation structure. By comparing our results to previous tomography, geology, and geophysical studies we are able to validate our findings and connect localized near‐surface studies with deeper, regional models. Specifically, we are able to resolve shallow basins, including the Copper River, Cook Inlet, Yukon Flats, Nenana, and a variety of other shallower basins. Additionally, we gain insight on the interaction between the upper mantle wedge, asthenosphere, and active and nonactive volcanism along the Aleutians and Denali volcanic gap, respectively. We observe thicker crust beneath the Brooks Range and south of the Denali fault within the Wrangellia Composite Terrane and thinner crust in the Yukon Composite Terrane in interior Alaska. We also gain new perspective on the Wrangell Volcanic Field and its interaction between surrounding asthenosphere and the Yakutat Terrane.

show abstract

“…Finzel et al, (2011) suggest that the western part of the Yakutat block started colliding at 43 Ma and stopped around 23 Ma but the eastern part started colliding at 10 Ma and continues to present, driving the exceptional high-elevation relief of the St. Elias-Chugach mountain ranges. This collision zone presents one of the highest deformation rates in North America (Marechal et al, 2015;Pavlis et al, 2019).…”

Section: 1029/2019jb018837mentioning

confidence: 99%

“…the Yakutat microplate currently moves northwestward, which means that the Wrangell slab is subducting obliquely. The Wrangell slab thus may be connected to the Yakutat slab to the west and could represent the early stage of a slab tear (Pavlis et al, 2019). Improved local resolution is likely necessary to investigate this hypothesis.…”

Section: 1029/2019jb018837mentioning

confidence: 99%

The Upper Mantle Structure of Northwestern Canada From Teleseismic Body Wave Tomography

et al. 2020

View full text Add to dashboard Cite

The Northern Canadian Cordillera (NCC) is an actively deforming orogenic belt in northwestern Canada. Geochemical and geophysical data show that the NCC is underlain by a thin and hot lithosphere, in contrast with the adjacent cold and thick cratonic lithosphere to the east. This juxtaposition of cold/hot and thick/thin lithosphere across a narrow transition zone has important implications for regional geodynamics. The recent deployment of USArray Transportable Array and other seismic stations across Alaska, USA, and northwestern Canada allows us to image lithosphere and upper mantle three‐dimensional seismic velocity structure at significantly improved resolution. Our model reveals a broad high‐velocity anomaly across northern Yukon and Northwest Territories, which is interpreted as buried cratonic lithosphere and which we refer to as the Mackenzie craton. Another prominent high‐velocity anomaly is imaged beneath northeastern British Columbia and is interpreted to indicate cratonic lithosphere beneath the Northern Rocky Mountains. These two mechanically strong lithospheric blocks, also suggested by regional magnetic data, are interpreted to buttress the ends of the Mackenzie Mountains fold and thrust belt, guiding intervening cordilleran mantle flow toward the Canadian Shield and controlling the arcuate geometry of the Mackenzie Mountains fold and thrust belt. Both P and S wave models also reveal the signature of a northward dipping, subducting Wrangell slab across the southern region of the Alaska/Yukon border. Strong P and S wave velocity contrasts across the Tintina Fault suggest that it is a lithosphere‐scale shear zone that extends into the upper mantle beneath the NCC and demarcates distinct regions of lithospheric mantle.

show abstract

A unified three-dimensional model of the lithospheric structure at the subduction corner in southeast Alaska: Summary results from STEEP

Cited by 28 publications

References 71 publications

A 3‐D Shear Velocity Model of the Crust and Uppermost Mantle Beneath Alaska Including Apparent Radial Anisotropy

A 3‐D Shear Velocity Model of the Crust and Uppermost Mantle Beneath Alaska Including Apparent Radial Anisotropy

Shear Velocity Model of Alaska Via Joint Inversion of Rayleigh Wave Ellipticity, Phase Velocities, and Receiver Functions Across the Alaska Transportable Array

The Upper Mantle Structure of Northwestern Canada From Teleseismic Body Wave Tomography

Contact Info

Product

Resources

About