Phyllite, slate, and black shale

Unit symbol: Dyp
Age range Devonian? (419.2 to 358.9 Ma)
Lithology: Sedimentary
Group name: Clastic and carbonate rocks of the Yukon Flats Basin
Dark-gray to black phyllite and schistose siltstone interbedded with subordinate amounts of quartz wacke and sheared slate- and chert-pebble conglomerate (Brosgé and others, 1973; Brosgé and Reiser, 2000) in northeast Alaska. In the Coleen quadrangle, unit consists of laminated dark-gray, light-gray, and greenish-gray clay and silt phyllite; minor very fine-grained, thin-bedded sandstone Brosgé and Reiser (1969). In the Christian quadrangle, Brosgé and Reiser (2000) subdivided the unit along the East Fork of the Chandalar River; on the east the unit contains more siltstone, is darker-colored, and locally recrystallized. Brosgé and Reiser (2000) assigned the entire unit to the Venetie terrane in the Christian quadrangle, whereas Moore and others (1994) assigned the unit to the slate- and graywacke-bearing Slate Creek terrane of the southern Brooks Range. The rocks in the Beaver quadrangle were assigned to the Slate Creek thrust sheet of the Angayucham-Tozitna terrane by Patton and others (1994a). As shown here, all of the rock units assigned to this map unit are spatially associated with the Angayucham, Tozitna, and Innoko assemblages and Rampart Group units of this map

Source map information

Source map Brosge, W.P., Reiser, H.N., and Yeend, Warren, 1973, Reconnaissance geologic map of the Beaver quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-525, scale 1:250,000.
Symbol Dp
Unit name Phyllite
Description Dark-gray to black phyllite and schistose siltstone interbedded with subordinate amounts of quartz wacke and sheared slate- and chert-pebble conglomerate. Age probably Devonian
Lithology Metamorphic

Correlated geologic units

Label Dyp
Description Phyllite, slate or black shale
Geologic age Early-Devonian to Late-Devonian
Geologic setting Metasedimentary, low-grade
Lithology Form Importance
Phyllite < Metaclastic < Metasedimentary < Metamorphic Major
Black-shale < Shale < Mudstone < Clastic < Sedimentary Bed Major
Slate < Metaclastic < Metasedimentary < Metamorphic Indeterminate, major