Geologic map of Alaska

Wilson, Frederic H.

doi:10.3133/sim3340

Cited by 103 publications

(74 citation statements)

References 89 publications

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“…Presently, there are no glaciers in the Kuparuk River drainage. The sediments composing the Kuparuk River channel and adjacent Kuparuk aufeis field are relatively well sorted particles in the pebble to cobble range that comprise glacial outwash and alluvium of Quaternary Pliocene to Holocene age (Wilson et al, 2015). Snowmelt-generated peak discharge generally occurs in late May or early June (Kendrick et al, 2019).…”

Section: Kuparuk Aufeismentioning

confidence: 99%

Seasonal Subsurface Thaw Dynamics of an Aufeis Feature Inferred From Geophysical Methods

Terry¹,

Grunewald

Briggs³

et al. 2020

JGR Earth Surface

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Aufeis are sheets of ice unique to cold regions that originate from repeated flooding and freezing events during the winter. They have hydrological importance associated with summer flows and winter insulation, but little is known about the seasonal dynamics of the unfrozen sediment layer beneath them. This layer may support perennial groundwater flow in regions with otherwise continuous permafrost. For this study, ground penetrating radar (GPR) were collected in September 2016 (maximum thaw) and April 2017 (maximum frozen) at the Kuparuk aufeis field on the North Slope of Alaska. Supporting surface nuclear magnetic resonance data were collected during the maximum frozen campaign. These point‐in‐time geophysical data sets were augmented by continuous subsurface temperature data and periodic Structure‐from‐Motion digital elevation models collected seasonally. GPR and difference digital elevation model data showed up to 6 m of ice over the sediment surface. Below the ice, GPR and nuclear magnetic resonance identified regions of permafrost and regions of seasonally frozen sediment (i.e., the active layer) underlain by a substantial lateral talik that reached >13‐m thickness. The seasonally frozen cobble layer above the talik was typically 3‐ to 5‐m thick, with freezing apparently enabled by relatively high thermal diffusivity of the overlying ice and rock cobbles. The large talik suggests that year‐round groundwater flow and coupled heat transport occurs beneath much of the feature. Highly permeable alluvial material and discrete zones of apparent groundwater upwelling indicated by geophysical and ground temperature data allows direct connection between the aufeis and the talik below.

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Section: Kuparuk Aufeismentioning

confidence: 99%

Seasonal Subsurface Thaw Dynamics of an Aufeis Feature Inferred From Geophysical Methods

Terry¹,

Grunewald

Briggs³

et al. 2020

JGR Earth Surface

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“…The distal margin of the Lamplugh rock avalanche lies approximately 8,600 m from the terminus of the Lamplugh Glacier, which flows into Glacier Bay. The source area consists of sedimentary and metamorphic rocks of the Triassic to Cretaceous Kelp Bay Group, including phyllite, quartzite, greenschist, greenstone, greywacke, and greywacke semischist (Wilson et al, 2015).…”

Section: The Lamplugh Rock Avalanchementioning

confidence: 99%

Using Stereo Satellite Imagery to Account for Ablation, Entrainment, and Compaction in Volume Calculations for Rock Avalanches on Glaciers: Application to the 2016 Lamplugh Rock Avalanche in Glacier Bay National Park, Alaska

2018

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The use of preevent and postevent digital elevation models (DEMs) to estimate the volume of rock avalanches on glaciers is complicated by ablation of ice before and after the rock avalanche, scour of material during rock avalanche emplacement, and postevent ablation and compaction of the rock avalanche deposit. We present a model to account for these processes in volume estimates of rock avalanches on glaciers. We applied our model by calculating the volume of the 28 June 2016 Lamplugh rock avalanche in Glacier Bay National Park, Alaska. We derived preevent and postevent 2‐m resolution DEMs from WorldView satellite stereo imagery. Using data from DEM differencing, we reconstructed the rock avalanche and adjacent surfaces at the time of occurrence by accounting for elevation changes due to ablation and scour of the ice surface, and postevent deposit changes. We accounted for uncertainties in our DEMs through precise coregistration and an assessment of relative elevation accuracy in bedrock control areas. The rock avalanche initially displaced 51.7 ± 1.5 Mm3 of intact rock and then scoured and entrained 13.2 ± 2.2 Mm3 of snow and ice during emplacement. We calculated the total deposit volume to be 69.9 ± 7.9 Mm3. Volume estimates that did not account for topographic changes due to ablation, scour, and compaction underestimated the deposit volume by 31.0–46.8 Mm3. Our model provides an improved framework for estimating uncertainties affecting rock avalanche volume measurements in glacial environments. These improvements can contribute to advances in the understanding of rock avalanche hazards and dynamics.

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“…This mechanism is particularly strong in streams that flow over sediment recently exposed in the wake of a retreating glacier (Anderson et al, 2000). The GOA drainage basin is composed of a spatially complex mix of carbonate and noncarbonate bedrock (Wilson et al, 2015); however, Anderson (2007) reported high rates of carbonate dissolution in streams draining glaciers on bedrock with only trace carbonate mineral concentrations.…”

Section: Introductionmentioning

confidence: 99%

Simulated Impact of Glacial Runoff on CO₂ Uptake in the Gulf of Alaska

Pilcher

Siedlecki

Hermann

et al. 2018

Geophysical Research Letters

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The Gulf of Alaska (GOA) receives substantial summer freshwater runoff from glacial meltwater. The alkalinity of this runoff is highly dependent on the glacial source and can modify the coastal carbon cycle. We use a regional ocean biogeochemical model to simulate CO2 uptake in the GOA under different alkalinity‐loading scenarios. The GOA is identified as a current net sink of carbon, though low‐alkalinity tidewater glacial runoff suppresses summer coastal carbon uptake. Our model shows that increasing the alkalinity generates an increase in annual CO2 uptake of 1.9–2.7 TgC/yr. This transition is comparable to a projected change in glacial runoff composition (i.e., from tidewater to land‐terminating) due to continued climate warming. Our results demonstrate an important local carbon‐climate feedback that can significantly increase coastal carbon uptake via enhanced air‐sea exchange, with potential implications to the coastal ecosystems in glaciated areas around the world.

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Geologic map of Alaska

Cited by 103 publications

References 89 publications

Seasonal Subsurface Thaw Dynamics of an Aufeis Feature Inferred From Geophysical Methods

Seasonal Subsurface Thaw Dynamics of an Aufeis Feature Inferred From Geophysical Methods

Using Stereo Satellite Imagery to Account for Ablation, Entrainment, and Compaction in Volume Calculations for Rock Avalanches on Glaciers: Application to the 2016 Lamplugh Rock Avalanche in Glacier Bay National Park, Alaska

Simulated Impact of Glacial Runoff on CO₂ Uptake in the Gulf of Alaska

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Geologic map of Alaska

Cited by 103 publications

References 89 publications

Seasonal Subsurface Thaw Dynamics of an Aufeis Feature Inferred From Geophysical Methods

Seasonal Subsurface Thaw Dynamics of an Aufeis Feature Inferred From Geophysical Methods

Using Stereo Satellite Imagery to Account for Ablation, Entrainment, and Compaction in Volume Calculations for Rock Avalanches on Glaciers: Application to the 2016 Lamplugh Rock Avalanche in Glacier Bay National Park, Alaska

Simulated Impact of Glacial Runoff on CO2 Uptake in the Gulf of Alaska

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Simulated Impact of Glacial Runoff on CO₂ Uptake in the Gulf of Alaska