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Crustal-scale structural architecture, shortening, and exhumation of an active, eroding orogenic wedge (Chugach/St Elias Range, southern Alaska)

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dc.creator Meigs, Andrew
dc.creator Johnston, Sarah
dc.creator Garver, John
dc.creator Spotila, James
dc.date.accessioned 2012-02-14T21:55:36Z
dc.date.available 2012-02-14T21:55:36Z
dc.date.issued 2008
dc.identifier.citation Meigs, A., S. Johnston, J. Garver, and J. Spotila (2008), Crustal-scale structural architecture, shortening, and exhumation of an active, eroding orogenic wedge (Chugach/St Elias Range, southern Alaska), Tectonics, 27, TC4003, doi:10.1029/2007TC002168. en_US
dc.identifier.uri http://hdl.handle.net/1957/27759
dc.description This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/tc/. en_US
dc.description.abstract Active mountain building associated with the accretion of the Yakutat microplate (YT) in southern Alaska is characterized through the combination of a new balanced cross section and new low-temperature cooling ages. This analysis constrains the amount and timing of shortening, the spatial and temporal trends of exhumation, and the interplay between structural development and exhumation. A fold-and-thrust belt comprising three principal thrust sheets (the Hope Creek, Sullivan, and an offshore thrust sheet from north to south) characterizes the YT internal structure, which has absorbed a minimum of ~82 km shortening. Assuming shortening and foreland basin development occurred contemporaneously, the shortening rate across the YT is ~13–14 mm/a after 5.6 Ma. Detrital apatite fission track ages, from south to north, are unreset along the southern edge of the Sullivan thrust sheet at the coast, are reset and have ages younger than 6.3 Ma within the thrust belt, and have reset cooling ages of ~13 Ma in the North American upper plate. Only the zircon samples from the northern, internal YT are potentially reset. Exhumation rates within the thrust belt vary from 0.3 ± 0.1 mm/a to 4 ± 1.8 mm/a. Combining the thermochronometric and structural data indicate that wedge exhumation since ~6 Ma is 500 km² and that particle trajectories have larger horizontal than vertical components. Whereas exhumation and shortening have been focused on the windward side of the Chugach/St. Elias Range since ~6 Ma, the cooling ages do not uniquely distinguish between orographically versus tectonically controlled erosion. en_US
dc.description.sponsorship Research was supported by NSF grant EAR-0001192 and NASA grant NASA (NAG-5-7646). Steve Reese and the OSU Triga Radiation Center are thanked for irradiation of our samples. en_US
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.ispartofseries Tectonics en_US
dc.relation.ispartofseries Vol. 27 no. TC4003 en_US
dc.subject fold-and-thrust belt en_US
dc.subject exhumation en_US
dc.subject microplate en_US
dc.title Crustal-scale structural architecture, shortening, and exhumation of an active, eroding orogenic wedge (Chugach/St Elias Range, southern Alaska) en_US
dc.type Article en_US
dc.description.peerreview yes en_US
dc.identifier.doi 10.1029/2007TC002168


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