Victoria Creek metamorphic rocks

Unit symbol: Tvc
Age range Tertiary, Paleocene metamorphism (66 to 56 Ma)
Lithology: Metamorphic
Group name: Victoria Creek metamorphic rocks
Dominantly medium- to medium-dark-gray garnetiferous quartz-mica schist and amphibolite, but includes slate and shale in the Livengood quadrangle. Locally has gneissic texture. Minor white to light-gray, medium- to coarse-grained, thin- to medium-bedded, typically finely laminated marble and very minor quartzite occurs in the Tanana quadrangle. Unit outcrops as large fault slivers or “lozenges” along a strand of the Tintina-Kaltag Fault System in the Livengood (Weber and others, 1992) and Tanana quadrangles (Reifenstuhl and others, 1997). In the Tanana quadrangle, geophysical interpretation cited in Reifenstuhl and others (1997) and outcrop patterns suggest a steep northwest contact with rocks of the Tozitna assemblage and a moderately southeast-dipping southeast contact. Protolith age is unknown and, although Reifenstuhl and others (1997) and Dusel-Bacon and others (1989) suggest a Ruby or Yukon-Tanana metamorphic complex origin, Weber and others (1992) suggest a possible protolith of Tozitna sedimentary rocks (see section on the Angayucham, Tozitna, and Innoko assemblages and Rampart Group (unit KMm) and included subunits). Includes the Raven Creek Hill unit of Weber and others (1992) and units pTam, pTas, pTaq of Reifenstuhl and others (1997). Also includes light- to medium-gray, fine-grained, recrystallized sucrose-textured, hard, dense, cryptically layered quartz arenite interbedded with the pelitic schist unit. Exposures are rare and typically consist of blocky, black lichen-covered talus. A black opaque mineral composes as much as 3 percent of the quartzite. Quartzite unit is uncommon and differentiated where possible

Source map information

Source map Reifenstuhl, R.R., Dover, J.H., Pinney, D.S., Newberry, R.J., Clautice, K.H., Liss, S.A., Blodgett, R.B., Bundtzen, T.K., and Weber, F.R., 1997, Geologic map of the Tanana B-1 quadrangle, central Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-15a, 17 p., 1 sheet, scale 1:63,360.
Symbol pTas
Unit name Medium- to coarse-grained schist and amphibolite
Description Gray to brown, red brown-weathering, medium- to coarse-crystalline, locally garnetiferous and staurolite-bearing, schist and green-black hornblende amphibolite. Diagnostic assemblages include garnet-staurolite-biotite-muscovite-quartz calcic plagioclase-sillimanite-kyanite in pelitic rocks and hornblende-calcic plagioclase-quartz-magnetite in amphibolites. Garnets up to 1 cm in diameter characterize the metapelitic rocks in hand specimen. Preservation of earlier foliation in rotated garnets and distinctive compositional zonation in garnets indicates multiple periods of amphibolite-facies metamorphism. Calc-silicate schist, containing diopside, actinolite, and epidote group minerals occurs locally. The epidote-hornblende plagioclase-actinolite-chlorite schist is derived from mafic volcanic or volcaniclastic protolith
Lithology Metamorphic

Correlated geologic units

Label Tmsa
Description Schist and amphibolite, Yukon-Tanana Upland associated with Victoria Creek fault
Geologic age Tertiary to Paleocene
Geologic setting Metamorphic, undivided
Lithology Form Importance
Amphibolite < Metamorphic Major
Quartz-feldspar-schist < Schist < Metamorphic Major
Calc-silicate-schist < Schist < Metamorphic Minor