Accretion and subduction tectonics in the Chugach Mountains and Copper River Basin, Alaska: Initial results of the Trans-Alaska Crustal Transect

Page, Robert A.; Plafker, George; Fuis, Gary S.; Nokleberg, Warren J.; Ambos, Elizabeth L.; Mooney, Walter D.; Campbell, David L.

doi:10.1130/0091-7613(1986)14<501:aastit>2.0.co;2

Cited by 67 publications

(19 citation statements)

References 5 publications

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“…This hypothesis would favor relatively shallow or low angle subduction during the different accretionary processes. This idea has already been proposed by Monger et al [1985] and Page et al [1986] for the Western Cordillera of North America based on deep seismic reflection profiling undertaken in Alaska. If the dipping crust‐mantle conductor observed beneath the Coast Belt is indeed mapping the path of the subducting slab then it may imply a change in the dip of the subduction with distance inland.…”

Section: Discussionmentioning

confidence: 99%

Lithospheric structure of the Yukon, northern Canadian Cordillera, obtained from magnetotelluric data

et al. 2004

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[1] Two goals of Lithoprobe's geoscientific studies in the Phanerozoic accretionary cordillera of western North America were to define the subsurface geometries of the terranes and to infer the physical conditions of the crust. These questions were addressed in Canada's southern cordillera a decade ago and have more recently been addressed in the northern cordillera, of which one component of the new studies is magnetotelluric (MT) profiling from ancestral North American rocks to the coast. We present a resistivity cross section, and its interpretation, of the northern cordillera derived from modeling data from 42 MT sites along a 470-km-long NE-SW profile. Beneath the Coast Belt (southwestern end of the profile) a deep crustal low-resistivity layer dips inland; we interpret the crustal part of this conductor as being due to metasedimentary rocks emplaced and metamorphosed during Paleocene Kula plate subduction. A strong lateral transition in lithospheric mantle resistivity exists below the Intermontane Belt that is spatially coincident with changes in chemical and isotopic characteristics of Tertiary to recent alkaline lavas, suggesting that isotopically enriched lithosphere related to the Coast Belt basalts extends partly beneath the Intermontane Belt. The unusually high lower crustal resistivity in the Intermontane and Omineca Belts, similar in value to the resistivity found in the unextended part of central British Columbia, excludes the presence of fluids or conducting metasediments. Finally, our resistivity model displays strong lateral variation of the middle and lower crust between different terranes within the same belt, as a result of the complex structural evolution of the lithosphere.

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Section: Discussionmentioning

confidence: 99%

Lithospheric structure of the Yukon, northern Canadian Cordillera, obtained from magnetotelluric data

et al. 2004

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“…Comparably high upper-crustal velocities on the continents have been found beneath Alaska (Page et al 1986), Vancouver Island (Spence et al 1985;Green et af. 1986) and several locations in California (Fuis et al 1984;Hwang & Mooney 1986; Zucca et af.…”

Section: Nj3 Alpha Ridge Complex-not Continentalmentioning

confidence: 91%

Canadian expedition to study the Alpha Ridge complex: results of the seismic refraction survey

Asudeh

Green

Forsyth

1988

Geophysical Journal International

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A crustal-scale seismic refraction survey has been conducted in the Arctic Ocean across the NE Alpha Ridge complex and its northern flank within the SE Makarov Basin. The data from the four reversed profiles have been analysed using 1-D and 2-D synthetic seismogram modelling schemes. Upper crustal velocities beneath these parts of the Alpha Ridge complex and Makarov Basin are surprisingly uniform at 5.0-5.2 km s-l, increasing smoothly and rapidly to ~6 . 5 km sK1 at depths of only 4 3 km. Below this level the velocities continue to increase relatively smoothly, reaching values of ~7 . 0 km s-l at depths ranging from 14 to 19 km. Mantle-type velocities of 23.0 km sK1 are found at depths of 36-44 km beneath some regions of the Alpha Ridge complex and 21-25 km beneath the SE Makarov Basin. Based on these results and other geophysical and geological data from the Arctic Ocean we interpret the Alpha Ridge complex as an Icelandic-type structure generated by Mantle Plume activity, and we suggest that the region of Makarov Basin surveyed is underlain by a thick oceanic crustal section.

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“…In each block, the foliation is often steeply dipping ( e.g. Page et al, 1986;Goodwin et al, 1989 ) and rocks have metasedimentary compositions with a high phyllosilicate content. Strike-slip faults separating blocks may also be expected to have at least a crustal extent and therefore vertical structures.…”

Section: The Alaskan Accretionmentioning

confidence: 99%

A quantitative evaluation of the contribution of crustal rocks to the shear-wave splitting of teleseismic SKS waves

Barruol

Mainprice

1993

Physics of the Earth and Planetary Interiors

182

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Accretion and subduction tectonics in the Chugach Mountains and Copper River Basin, Alaska: Initial results of the Trans-Alaska Crustal Transect

Cited by 67 publications

References 5 publications

Lithospheric structure of the Yukon, northern Canadian Cordillera, obtained from magnetotelluric data

Lithospheric structure of the Yukon, northern Canadian Cordillera, obtained from magnetotelluric data

Canadian expedition to study the Alpha Ridge complex: results of the seismic refraction survey

A quantitative evaluation of the contribution of crustal rocks to the shear-wave splitting of teleseismic SKS waves

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