Geologic map of the Valdez A-4, B-3, B-4, C-3, C-4, and D-4 quadrangles, northern Chugach Mountains and southern Copper River basin, Alaska

Plafker, George; Lull, José; Nokleberg, Warren J.; Pessel, G.H.; Wallace, Wesley K.; Winkler, Gary R.

doi:10.3133/ofr89569

Cited by 5 publications

(2 citation statements)

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“…Data from southeastern Alaska come from Becker (1898), Wright and Wright (1905), Knopf (1912), and Reed and Coats (1941). Data on dike orientations come from the previously listed sources and Park (1933), Winkler (1992), and Plafker et al (1992). A: Poles to bedding and cleavage.…”

Section: District-by-district Dike and Fault Datamentioning

confidence: 99%

Brittle deformation along the Gulf of Alaska margin in response to Paleocene-Eocene triple junction migration

Haeussler¹,

Bradley²,

Goldfarb³

2003

Geology of a Transpressional Orogen Developed During Ridge-Trench Interaction Along the North Pacific Margin

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A spreading center was subducted diachronously along a 2200 km segment of what is now the Gulf of Alaska margin between 61 and 50 Ma, and left in its wake near-trench intrusions and high-T, low-P metamorphic rocks. Gold-quartz veins and dikes, linked to ridge subduction by geochronological and relative timing evidence, provide a record of brittle deformation during and after passage of the ridge. The gold-quartz veins are typically hosted by faults, and their regional extent indicates there was widespread deformation of the forearc above the slab window at the time of ridge subduction. Considerable variability in the strain pattern was associated with the slab window and the trailing plate. A diffuse network of dextral, sinistral, and normal faults hosted small lode-gold deposits (<50,000 oz) in south-central Alaska, whereas crustal-scale dextral faults in southeastern Alaska are spatially associated with large gold deposits (up to 800,000 oz).We interpret the gold-quartz veins as having formed above an eastward-migrating slab window, where the forearc crust responded to the diminishing infl uence of the forward subducting plate, the increasing infl uence of the trailing plate, and the thermal pulse and decreased basal friction from the slab window. In addition, extensional deformation of the forearc resulted from the diverging motions of the two oceanic plates at the margins of the slab window. Factors that complicate interpretations of fault kinematics and near-trench dike orientations include a change in plate motions at ca. 52 Ma, northward translation of the accretionary complex, oroclinal bending of the south-central Alaska margin, and subduction of transform segments. We fi nd the pattern of syn-ridge subduction faulting in southern Alaska is remarkably similar to brittle faults near the Chile triple junction and to earthquake focal mechanisms in the Woodlark basin-the two modern sites of ridge subduction. Therefore, extensional and strike-slip deformation above slab windows may be a common occurrence.

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Section: District-by-district Dike and Fault Datamentioning

confidence: 99%

Brittle deformation along the Gulf of Alaska margin in response to Paleocene-Eocene triple junction migration

Haeussler¹,

Bradley²,

Goldfarb³

2003

Geology of a Transpressional Orogen Developed During Ridge-Trench Interaction Along the North Pacific Margin

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“…The Wrangell volcanic field is constructed on Wrangellia terrane, an assemblage of allochthonous tectonostratigraphic terranes of Paleozoic and Mesozoic age including island arcs and related sediments, Mesozoic flood basalts, igneous intrusions, and limestones (Bruns 1983;Pflaker et al 1989;Plafker and Berg 1994;Preece 1997). A small portion of the southeastern part of the field overlies the Alexander terrane (Miller and Richter 1994 (Richter 1976;MacKevett 1978;Cook and Rowlands 2002).…”

Section: Nam E O F Volcanomentioning

confidence: 99%

Resedimentation of the late Holocene White River ash, Yukon territory, Canada and Alaska, USA

West¹

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The author has granted a non exclusive license allowing Library and Archives Canada to reproduce, publish, archive, preserve, conserve, communicate to the public by telecommunication or on the Internet, loan, distribute and sell theses worldwide, for commercial or non commercial purposes, in microform, paper, electronic and/or any other formats. AVIS: L'auteur a accorde une licence non exclusive permettant a la Bibliotheque et Archives Canada de reproduire, publier, archiver, sauvegarder, conserver, transmettre au public par telecommunication ou par I'lnternet, preter, distribuer et vendre des theses partout dans le monde, a des fins commerciales ou autres, sur support microforme, papier, electronique et/ou autres formats.

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A tribute to George Plafker

Fuis

Haeussler

Atwater

2015

Quaternary Science Reviews

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a b s t r a c tIn a long and distinguished career, George Plafker made fundamental advances in understanding of megathrust tectonics, tsunami generation, paleoseismology, crustal neotectonics, and Alaskan geology, chiefly by means of geological field observations. George discovered that giant earthquakes result from tens of meters of seismic slip on subduction megathrusts, and he did this before the theory of plate tectonics had become a paradigm. The discovery was founded on George's comprehensive mapping of land-level changes in the aftermath of the 1964 earthquake in Alaska, and on his follow-up mapping, in 1968, in the region of the 1960 earthquakes in Chile. The mapping showed paired, parallel belts of coseismic uplift largely offshore and coseismic subsidence mostly onshore e a pattern now familiar as the initial condition assumed in simulations of subduction-zone tsunamis. George recognized, moreover, that splay faulting can play a major role in tsunami generation, and he also distinguished carefully between tectonic and landslide sources for the multiple tsunamis that accounted for nearly all the fatalities associated with the 1964 Alaska earthquake. George's classic monographs on the 1964 earthquake include findings on subduction-zone paleoseismology that he soon extended to include stratigraphic evidence for cyclic vertical deformation at the Copper River Delta, as well as recurrent uplift evidenced by flights of marine terraces at Middleton Island. As a geologist of earthquakes, George also clarified the tectonics and hazards of crustal faulting in Alaska, California, and other areas worldwide. All the while, George was mapping bedrock geology in Alaska, where he contributed importantly to today's understanding of how terranes were accreted and modified. Especially important was his documentation of the origin, movement, subduction, and collision of the Yakutat terrane in southern Alaska.Published by Elsevier Ltd.

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Geologic map of the Valdez A-4, B-3, B-4, C-3, C-4, and D-4 quadrangles, northern Chugach Mountains and southern Copper River basin, Alaska

Cited by 5 publications

References 0 publications

Brittle deformation along the Gulf of Alaska margin in response to Paleocene-Eocene triple junction migration

Brittle deformation along the Gulf of Alaska margin in response to Paleocene-Eocene triple junction migration

Resedimentation of the late Holocene White River ash, Yukon territory, Canada and Alaska, USA

A tribute to George Plafker

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