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Mesozoic and Cenozoic tectonics of the eastern and central Alaska Range: Progressive basin development and deformation in a suture zone

2002; Geological Society of America; Volume: 114; Issue: 12 Linguagem: Inglês

10.1130/0016-7606(2002)114 2.0.co;2

1943-2674

Kenneth D. Ridgway, Jeffrey M. Trop, Warren J. Nokleberg, Cameron M. Davidson, Kevin R. Eastham,

earthquake and tectonic studies

Research Article| December 01, 2002 Mesozoic and Cenozoic tectonics of the eastern and central Alaska Range: Progressive basin development and deformation in a suture zone Kenneth D. Ridgway; Kenneth D. Ridgway 1Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-1397, USA Search for other works by this author on: GSW Google Scholar Jeffrey M. Trop; Jeffrey M. Trop 1Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-1397, USA Search for other works by this author on: GSW Google Scholar Warren J. Nokleberg; Warren J. Nokleberg 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA Search for other works by this author on: GSW Google Scholar Cameron M. Davidson; Cameron M. Davidson 3Department of Geology, Beloit College, Beloit, Wisconsin 53511, USA Search for other works by this author on: GSW Google Scholar Kevin R. Eastham Kevin R. Eastham 4Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-1397, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2002) 114 (12): 1480–1504. https://doi.org/10.1130/0016-7606(2002)114 2.0.CO;2 Article history received: 12 Feb 2001 rev-recd: 30 Apr 2002 accepted: 09 May 2002 first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Kenneth D. Ridgway, Jeffrey M. Trop, Warren J. Nokleberg, Cameron M. Davidson, Kevin R. Eastham; Mesozoic and Cenozoic tectonics of the eastern and central Alaska Range: Progressive basin development and deformation in a suture zone. GSA Bulletin 2002;; 114 (12): 1480–1504. doi: https://doi.org/10.1130/0016-7606(2002)114 2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Analysis of late Mesozoic and Cenozoic sedimentary basins, metamorphic rocks, and major faults in the eastern and central Alaska Range documents the progressive development of a suture zone that formed as a result of collision of an island-arc assemblage (the Wrangellia composite terrane) with the former North American continental margin. New basin-analysis, structural, and geochronologic data indicate the following stages in the development of the suture zone: (1) Deposition of 3–5 km of Upper Jurassic–Upper Cretaceous marine strata (the Kahiltna assemblage) recorded the initial collision of the island-arc assemblage with the continental margin. The Kahiltna assemblage exposed in the northern Talkeetna Mountains represents a Kimmeridgian–Valanginian backarc basin that was filled by northwestward-flowing submarine-fan systems that were transporting sediment derived from Mesozoic strata of the island-arc assemblage. The Kahiltna assemblage exposed in the southern Alaska Range represents a Valanginian–Cenomanian remnant ocean basin filled by west-southwestward–flowing submarine-fan systems that were transporting sediment derived from Paleozoic continental-margin strata uplifted in the along-strike suture zone. A belt of retrograde metamorphism and a regional anticlinorium developed along the continental margin from 115 to 106 Ma, roughly coeval with the end of widespread deposition in the Kahiltna sedimentary basins. (2) Metamorphism of submarine-fan deposits of the Kahiltna ba sin, located near the leading edge of the island-arc assemblage, occurred at ca. 74 Ma, as determined from a new U-Pb zircon age for a synkinematic sill. Coeval with metamorphism of deposits of the Kahiltna basin in the southern part of the suture zone was development of a thrust-top basin, the Cantwell basin, in the northern part of the suture zone. Geologic mapping and compositional data suggest that the 4 km of Upper Cretaceous nonmarine and marginal marine sedimentary strata in this basin record regional subaerial uplift of the suture zone. (3) Shortening and exhumation of the suture zone peaked from 65 to 60 Ma on the basis of metamorphic and geochronologic data. In the southern part of the suture zone, submarine-fan deposits of the Kahiltna basin, which had been metamorphosed to kyanite schists at ∼25 km depth and ∼650 °C, were exhumed and cooled through the biotite closure temperature (∼300 °C) by ca. 62 Ma. In the northern part of the suture zone, this time period was marked by shortening, uplift, and erosion of sedimentary strata of the Cantwell basin. (4) From 60 to 54 Ma, ∼3 km of volcanic strata were deposited over deformed sedimentary strata of the Cantwell basin, and several granitic plutons (the McKinley sequence) were emplaced along the suture zone. (5) Following igneous activity, strike-slip displacement occurred from ca. 54 to 24 Ma along the Denali fault system, which had developed in the existing suture zone. Late Eocene–Oligocene strike-slip displacement resulted in the formation of several small sedimentary basins along the Denali fault system. (6) Regional transpressive shortening characterized the suture zone from ca. 24 Ma to the present. Flexural subsidence, related to regional shortening, is represented by late Eocene to Holocene nonmarine deposits of the Tanana foreland basin. Regional subsidence resulted in Miocene coal seams up to 20 m thick and well-developed lacustrine deposits. Overlying the Miocene deposits are ∼1.2 km of Pliocene and Holocene conglomeratic deposits. Compositional and paleocurrent data from these younger deposits record regional Neogene uplift of the suture zone and recycling of detritus from older basins to the south that had become incorporated into the uplifted suture zone. Geologic mapping of major thrust faults along the northern and southern margins of the suture zone documents Paleozoic strata thrust over both Pliocene fluvial deposits and Quaternary glacial deposits of the Tanana basin. These mapping relationships provide evidence that regional shortening continues to the present in the eastern and central Alaska Range. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.