Regional magnetic anomalies, crustal strength, and the location of the northern Cordilleran fold-and-thrust belt

Saltus, Richard W.; Hudson, Travis

doi:10.1130/g23470a.1

Cited by 30 publications

(39 citation statements)

References 12 publications

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“…First, the high Vp/Vs region overlaps with a crustal-scale magnetic high in southern Alaska, which was suggested as the results of mafic magmatism during the Middle to Late Triassic time based on gravity modeling by Saltus and Hudson (2007). First, the high Vp/Vs region overlaps with a crustal-scale magnetic high in southern Alaska, which was suggested as the results of mafic magmatism during the Middle to Late Triassic time based on gravity modeling by Saltus and Hudson (2007).…”

Section: Discussionmentioning

confidence: 94%

“…The observed sharp Moho step also marks a change in crustal composition based on Vp/Vs variations (Brennan et al, 2011). Magnetic and gravity modeling also requires significant amounts of mafic rocks in the middle to lower crust in southern Alaska (Saltus & Hudson, 2007). Magnetic and gravity modeling also requires significant amounts of mafic rocks in the middle to lower crust in southern Alaska (Saltus & Hudson, 2007).…”

Section: Introductionmentioning

confidence: 90%

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Crustal Structure in Alaska From Receiver Function Analysis

Zhang

2019

Geophysical Research Letters

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New maps of crustal thickness and Vp/Vs in Alaska and western Canada were obtained using P receiver functions recorded at 198 stations from the USArray Transportable Array and the Alaska Regional Network. Our results indicate that topography and Moho depth are correlated as crustal thickness varies from 28 to 43 km across Alaska. A thick crust occurs under the mountains in the south and north with relatively thin crust in central Alaska. The deepest crustal root beneath the Brooks Range may have lost its buoyancy based on Airy isostasy. In addition, a buoyant upper mantle is required to support the high topography in east central Alaska. Vp/Vs is determined between 1.7 and 1.8 beneath most of Alaska except a high average of 1.9 in the south central region. We attribute this high Vp/Vs to the underplating of Yakutat and Pacific oceanic crust.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 90%

Crustal Structure in Alaska From Receiver Function Analysis

Zhang

2019

Geophysical Research Letters

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“…They infer that this process is facilitated by the presence of a tectonic “buttress” such that the Arctic Alaska terranes in the Brooks Range provide a backstop that guides the large‐scale orogenic flow along the Alaskan orocline. Saltus and Hudson [] draw a similar conclusion to explain the along‐strike variation in the inboard limit of deformation along the northern Alaska and Yukon segments of the Cordilleran fold‐and‐thrust belt.…”

Section: Deformation Of the Continentmentioning

confidence: 99%

“…In section 3, we summarize some comprehensive models of large‐scale strain that we incorporate into our interpretation of SRF results. Our analysis focuses on a few first‐order, continental lithosphere‐scale features: (1) the contrast in “stability” between the Arctic Alaska region and the greater back‐arc/arc region [ Hyndman et al ., ; Saltus and Hudson , ] and (2) the deformation of the North American lithosphere south of the Denali and Tintina Fault systems [e.g., Leonard et al , ; Cross and Freymueller , ; Finzel et al ., , ]. The first feature may serve as a buttress for deformation, as first described by Redfield et al .…”

Section: Introductionmentioning

confidence: 99%

Lithospheric discontinuity structure in Alaska, thickness variations determined bySpreceiver functions

O'Driscoll

Miller

2015

Tectonics

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We present the first broad-scale image of lithospheric thickness across the major tectonic domains of Alaska based on S wave receiver functions and joint interpretation with the potential field, seismic velocity, and heat flow measurements. Thus, we provide context for the distribution of strain throughout the Alaskan orocline. In the north, below the Brooks Range, a 130 km thick lithosphere is resolved, consistent with the presence of strong lithosphere that deflects strain to the south into central and southern Alaska. In southern Alaska beneath the Chugach and St. Elias Mountains, multiple interfaces are present, and we interpret a thinner (80-90 km) North American lithosphere above a deeper interface that represents the base of the Yakutat microplate, thereby extending it to the area below the Wrangell Volcanic Field and St. Elias Mountains. Immediately north of the E-W striking Denali Fault, shallow negative conversions (80 km) denote thin lithosphere in the greater back-arc region where heat flow is observed to be high. Thin lithosphere in eastern Alaska and adjacent Yukon Territory coincides with the occurrence of inboard crustal seismicity and may be indicative of transmitted compression caused by the collision of the Yakutat microplate. Relatively thin lithosphere (<90 km) south of the Arctic Alaska domain that is deforming throughout the Alaskan orocline may result from lithospheric thinning associated with guided deformation. Expansion of this model using the upcoming Transportable Array will be critical to establish lateral continuity (or lack thereof) of lithospheric structure and directly discriminate between existing regional deformation models.

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“…Furthermore, the North Slope subterrane and the rest of the Arctic Alaska-Chukotka microplate are separated by early Paleozoic ocean-island basalts in the Franklin Mountains (Moore, 1987) and arc volcanics in the Doonerak fenster (Julian and Oldow, 1998). A suture between the North Slope subterrane and the rest of the Arctic Alaska-Chukotka microplate may be marked by low-amplitude magnetic anomalies in the southern North Slope (Grantz et al, 1991), and by a change in the aeromagnetic and gravity fabrics across the southern margin of the North Slope subterrane (Saltus and Hudson, 2007). The age of this putative suture and to what degree the Arctic Alaska-Chukotka microplate subterranes have a shared Neoproterozoic and Paleozoic history are unclear.…”

Section: Anatomy Of the Arctic Alaska-chukotka Microplatementioning

confidence: 99%

Neoproterozoic glaciation on a carbonate platform margin in Arctic Alaska and the origin of the North Slope subterrane

Macdonald

McClelland

Schrag

et al. 2009

Geological Society of America Bulletin

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The rotation model for the opening of the Canada Basin of the Arctic Ocean predicts stratigraphic links between the Alaskan North Slope and the Canadian Arctic islands. The Katakturuk Dolomite is a 2080-m-thick Neo protero zoic carbonate succession exposed in the northeastern Brooks Range of Arctic Alaska. These strata have previously been correlated with the pre-723 Ma Shaler Supergroup of the Amundson Basin. Herein we report new composite δ 13 C profi les and detrital zircon ages that test this connection. We go further and use stratigraphic markers and a compilation of δ 13 C chemostratigraphy from around the world, tied to U-Pb ages, to derive an age model for deposition of the Katakturuk Dolomite. In particular, we report the identifi cation of ca. 760 Ma detrital zircons in strata underlying the Katakturuk Dolomite. Moreover, a diamictite present at the base of the Katakturuk Dolomite is capped by a dark-colored limestone with peculiar roll-up structures. Chemostratigraphy and lithostratigraphy suggest this is an early-Cryogenian glacial diamictite-cap carbonate couplet and that deposition of the Katakturuk Dolomite spanned much of the late Neoproterozoic. Approximately 500 m above the diamictite, a micropeloidal dolomite, with idiosyncratic textures that are characteristic of basal Ediacaran cap carbonates, such as tubestone stromatolites, giant wave ripples, and decameters of pseudo morphosed former aragonite crystal fans, rests on a silicifi ed surface. Chemostratigraphic correlations also indicate a large increase in sedimentation rate in the upper ~1 km of the Katakturuk Dolomite and in the overlying lower Nanook Limestone. We suggest that the accompanying increase in accommodation space, along with the presence of two low-angle unconformities within these strata, are the product of late Ediacaran rifting along the southern margin of the North Slope subterrane. There are no strata present in the Amundson Basin that are potentially correlative with the late Neoproterozoic Katakturuk Dolomite, as the Cambrian Saline River Formation rests on the ca. 723 Ma Natkusiak Formation. Detrital zircon geochronology, chemostratigraphic correlations, and the style of sedimentation are inconsistent with both a Canadian Arctic origin of the North Slope subterrane and a simple rotation model for the origin of the Arctic Ocean. If the rotation model is to be retained, the exotic North Slope subterrane must have accreted to northwest Laurentia in the Early to Middle Devonian.

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Regional magnetic anomalies, crustal strength, and the location of the northern Cordilleran fold-and-thrust belt

Cited by 30 publications

References 12 publications

Crustal Structure in Alaska From Receiver Function Analysis

Crustal Structure in Alaska From Receiver Function Analysis

Lithospheric discontinuity structure in Alaska, thickness variations determined bySpreceiver functions

Neoproterozoic glaciation on a carbonate platform margin in Arctic Alaska and the origin of the North Slope subterrane

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