Structural geology and glacier dynamics, Bering and Steller Glaciers, Alaska

Bruhn, Ronald L.; Forster, R. R.; Ford, Andrew; Pavlis, Terry L.; Vorkink, Michael

doi:10.1130/2010.2462(11)

Cited by 6 publications

(18 citation statements)

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“…Large ice displacements during the surge refolded moraine loops on the glacier upslope from Malaspina Lake when the terminus advanced several kilometers toward the coast (Figures b and c) [ Muskett et al , ]. The tight hinges and subparallel limbs of the refolded moraine loops are a hallmark of ice flow around a buried bedrock ridge that is elongated in the direction of ice flow (Figures c and S1) [ Roush et al , ; Bruhn et al , ]. This northwest‐southeast elongated ridge is denoted “E2” in Figures and .…”

Section: Observations and Resultsmentioning

confidence: 99%

“…Bruhn et al [] investigated ice deformation above bedrock ridges during surging of the Bering Glacier in 1993–1994 [ Roush et al , ], and the structural geology of several other ridges located near the terminus of Steller Glacier are known from our own field observations and also mapping by Taliaferro []. These examples include ridges that were elongated parallel to ice flow as well as those that plunged beneath the glacier at high angle to flow.…”

Section: Discussionmentioning

confidence: 99%

“…The inability to directly observe and map these regional‐scale structures severely inhibits development of a robust structural framework for the orogen. This motivated us to use glacier flow patterns and glacier surface morphology to infer the nature of the topography at the base of the ice, and hence constrain the locations and kinematics of buried structures [ Ford et al , ; Bruhn et al , , ]. The work reported herein on Malaspina Glacier completes our coverage of major, ice‐covered structural boundaries within the Saint Elias orogen.…”

Section: Introductionmentioning

confidence: 99%

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Ice surface morphology and flow on Malaspina Glacier, Alaska: Implications for regional tectonics in the Saint Elias orogen

et al. 2014

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The Saint Elias Mountains in southern Alaska are located at a structural syntaxis where the coastal thrust and fold belt of the Fairweather plate boundary intersects thrust faults and folds generated by collision of the Yakutat Terrane. The axial trace of this syntaxis extends southeastward out of the Saint Elias Mountains and beneath Malaspina Glacier where it is hidden from view and cannot be mapped using conventional methods. Here we examine the surface morphology and flow patterns of Malaspina Glacier to infer characteristics of the bedrock topography and organization of the syntaxis. Faults and folds beneath the eastern part of the glacier trend northwest and reflect dextral transpression near the terminus of the Fairweather fault system. Those beneath the western part of the glacier trend northeast and accommodate folding and thrust faulting during collision and accretion of the Yakutat Terrane. Mapping the location and geometry of the structural syntaxis provides important constraints on spatial variations in seismicity, fault kinematics, and crustal shortening beneath Malaspina Glacier, as well as the position of the collisional deformation front within the Yakutat Terrane. We also speculate that the geometrical complexity of intersecting faults within the syntaxis formed a barrier to rupture propagation during two regional Mw 8.1 earthquakes in September 1899.

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Section: Observations and Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ice surface morphology and flow on Malaspina Glacier, Alaska: Implications for regional tectonics in the Saint Elias orogen

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“…The boundary between the central YFTB and the western syntaxis consists of a series of parallel‐trending faults zones found along strike that include the Bering Glacier structure [ Bruhn et al , 2010; Doser et al , 2007], the Kayak Island Zone [ Plafker , 1987; Worthington et al , 2008], and the lesser known Suckling Hills Fault. We build upon previous studies that have individually examined the structural importance of these structures [ Worthington et al , 2008; Bruhn et al , 2010; Plafker , 1987] and suggest that these structures form a single, segmented fault network bordering the eastern margin of the western syntaxis (Figure 2). This fault network may form the northeastern extension of the Aleutian megathrust as it transitions from the North America‐Pacific Plate boundary to the Yakutat‐North America microplate boundary [ Worthington et al , 2008; Bruhn et al , 2004; Eberhart‐Phillips et al , 2006].…”

Section: Introductionmentioning

confidence: 99%

“…Researchers have hypothesized that this boundary accommodates some component of convergence between the Yakutat microplate and North America [ Plafker et al , 1994; Bruhn et al , 2010]. However, whether these structures are recently active remains unanswered.…”

Section: Introductionmentioning

confidence: 99%

The Suckling Hills Fault, Kayak Island Zone, and accretion of the Yakutat microplate, Alaska

Chapman¹,

Worthington²,

Pavlis³

et al. 2011

Tectonics

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The Suckling Hills and Kayak Island are isolated mountain blocks located along strike from each other within the foreland of the St. Elias orogen in southern Alaska. These blocks preserve an erosional surface that was deformed by slip on northwest‐dipping reverse faults in the Pleistocene. We suggest that the Suckling Hills Fault and Kayak Island Zone form a segmented fault network that links with the Bering Glacier structure to the north. This fault network separates the central Yakataga fold and thrust belt from complex, multiply deformed structures in the western syntaxis. Ongoing accretion of the Yakutat microplate to North America results in translation of structures of the fold and thrust belt into the western syntaxis. The composite Suckling Hills Fault, Kayak Island Zone, and Bering Glacier structure may have formed because the older structures of the fold and thrust belt were unfavorably oriented within the western syntaxis region. This pattern of deformation provides a template for understanding the complex deformation within the core of the western syntaxis and predicts refolding and straightening of the western syntaxis margin with continued accretion. This study provides an analog for structural overprinting and changing deformation patterns through time in orogenic corners.

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The Rise and Fall of Alaska and Yukon Glaciers Detected by TOPEX/Poseidon and Jason‐2 Altimeters Using a Novel Glacier‐Threshold Method

et al. 2023

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There are about 27,000 glaciers in Alaska (Mcgrath et al., 2017;Pfeffer et al., 2014). The glaciers here began to retreat as early as the 18th century, and some small glaciers have disappeared in the 20th century (Molnia, 2008). Recent studies show that in the past half century, the rapidly melting glaciers in Alaska have contributed to a third of the global sea level rise (Zemp et al., 2019). This ice loss has been accelerating in the last decade (Hugonnet et al., 2021;Jakob et al., 2020). Mass losses associated with Alaska glacier melting have been detected by the Gravity Recovery and Climate Experiment (GRACE) data. Luthcke et al. (2008Luthcke et al. ( , 2013 first used GRACE mascon solutions to confirm significant mass losses in Alaska, similar to the results from the solutions using spherical harmonic expansions (Gardner et al., 2013;Jacob et al., 2012;Wouters et al., 2019). The latest time-varying gravity observations of GRACE and GRACE Follow-On show that the glacier-induced mass losses are intensifying

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Structural geology and glacier dynamics, Bering and Steller Glaciers, Alaska

Cited by 6 publications

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Ice surface morphology and flow on Malaspina Glacier, Alaska: Implications for regional tectonics in the Saint Elias orogen

Ice surface morphology and flow on Malaspina Glacier, Alaska: Implications for regional tectonics in the Saint Elias orogen

The Suckling Hills Fault, Kayak Island Zone, and accretion of the Yakutat microplate, Alaska

The Rise and Fall of Alaska and Yukon Glaciers Detected by TOPEX/Poseidon and Jason‐2 Altimeters Using a Novel Glacier‐Threshold Method

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