U-Pb zircon age data from meta-igneous rocks in the Clearwater Mountains, Mount Hayes A-6 Quadrangle, Alaska

Abstract

We report U-Pb zircon geochronology results for one metavolcanic and one metaplutonic rock sample from the Mount Hayes A-6 Quadrangle of central Alaska. These samples are representative of rock units assigned to the Clearwater terrane of Jones and others (1987), a sequence of greenschist-grade metavolcanic and metasedimentary rocks of poorly constrained age and tectonic origin. Our results indicate a crystallization age of 277.33 ± 11.84 Ma for a felsic metavolcanic rock, and a 268.05 ± 11.64 Ma crystallization age for a granitic metaplutonic unit intruding the former.

Magmatic and structural framework of PGE and other mineralization in northwestern Wrangellia, central Alaska

“…Mineral occurrences documented in the area, such as Bird's Beak (fig. 31; Ellis and others, 2004), are apparently related to ultramafic (Twelker and O'Sullivan, 2016). This metamorphosed pluton is spatially associated with the Mex prospect (fig.…”

“…Zircons from a stratigraphically conformable unit of mixed metatuff and metasedimentary rocks (unit Pcmt of Twelker and others, 2020) give an age of 277.3 ± 11.8 Ma, and a crosscutting body of medium-to coarse-grained granitic orthogneiss (unit Pcog of Twelker and others, 2020) yielded a magmatic crystallization age of 268.1 ± 11.6 Ma (13 zircons). A subordinate population of grains (nine zircons) have older ages ranging from 285 to 308 Ma; no grains had ages older than 308 Ma (Twelker and O'Sullivan, 2016).…”

40Ar/39Ar data from the Tanacross D-1 and D-2, Big Delta B-4 and B-5, and Mount Hayes A-6 quadrangles, Alaska

“…The Wrangellia project area lies along the Denali Highway in the eastern Wrangellia Terrane, which includes magmatic sulfide nickel-copper-cobalt and platinum-group element mineralization hosted in maficultramafic rocks in a structurally complex geologic setting. The sample presented in this report comes from the Clearwater Terrane, described by Jones and others (1987) as an isolated region of metamorphic rock with Permian protoliths (Twelker and O'Sullivan, 2016) caught up in the regional Talkeetna Shear Zone.…”