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TitlePaleozoic tectonic and metallogenetic evolution of pericratonic terranes in Yukon, northern British Columbia and eastern Alaska
AuthorNelson, J L; Colpron, M; Piercey, S J; Dusel-Bacon, C; Murphy, D C; Roots, C F
SourcePaleozoic evolution and metallogeny of pericratonic terranes at the Ancient Pacific Margin of North America, Canadian and Alaskan Cordillera; by Colrpon, M (ed.); Nelson, J L (ed.); Geological Association of Canada, Special Paper 45, 2006 p. 323-360; 1 CD-ROM Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20060157
PublisherGeological Association of Canada
Mediapaper; CD-ROM; digital; on-line
File formatpdf (Adobe Acrobat Reader); xls (Microsoft Excel)
ProvinceYukon; British Columbia
NTS92; 93; 94; 102; 103; 104; 105; 106C; 106D; 106E; 106F; 106L; 114; 115; 116; 117A; 117B; 117C; 117D; 117E; 117F; 117G; 117H
AreaAlaska; Canada; United States of America
Lat/Long WENS-156.0000 -114.0000 69.0000 49.0000
Subjectsgeneral geology; geochemistry; geochronology; metallic minerals; sedimentology; structural geology; tectonics; terranes; craton; deformation; metamorphic rocks; igneous rocks; sedimentary rocks; faults; plutons; continental margins; magmatic arcs; basalts; rhyolites; volcanogenic deposits; mineral deposits; Paleozoic
Illustrationslocation maps; geological sketch maps; graphs; geochemical plots; bar graphs; cross-sections, structural
ProgramAncient Pacific Margin NATMAP Project
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
Released2006 01 01
AbstractThe allochthonous, pericratonic Yukon-Tanana terrane (YTT) underlies much of southwest Yukon, easternmost Alaska
and the Coast and Cassiar mountains of northern B.C. Data obtained through the Ancient Pacific Margin NATMAP
Project (1998-2003) have substantially modified its extent, subdivided it into regional assemblages, and established distinct components of arc and back-arc affinity that define a west-facing Late Devonian to Early Permian arc. Most
of the former YTT in Alaska is now considered parautochthonous.
Some aspects of YTT appear foreign to the continent: intense Devonian-Mississippian arc magmatism, and affiliations
with the younger arc terranes of Quesnellia and Stikinia. A belt of Permian high-pressure rocks, a late Paleozoic marginal
ocean terrane, and Jurassic thrust faults intervene between it and the miogeocline. However, Precambrian detrital
zircon populations, ?Nd values and Pb isotopic ratios from Devonian-Mississippian syngenetic occurrences show
a strong affinity for the northern miogeocline. VHMS mineralization associated with A-type and intraplate volcanism
mark the YTT as a rifting frontal arc to continental back-arc during the Devonian-Mississippian. Simultaneously, the
northwestern continent margin became a broad, extending back-arc region, with normal faulting, coarse clastic
deposition, rift-related volcanism and syngenetic mineralization. Slab rollback drove regional extension, which culminated
in the opening of the Slide Mountain marginal ocean between the YTT arc and North America.
The mid-Permian marked a transition to convergent tectonic style - the closure of the Slide Mountain basin by shortlived
westward subduction under YTT. Within eastern (inboard) YTT, there was a brief phase of arc activity, east-vergent
thrust faulting, exhumation of high P/T rocks and deposition of synorogenic clastic rocks. By the end of the Permian,
YTT and its associated terranes, although still not accreted to their present locations, had once again become part of
the North American margin.

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