Tuffaceous volcanic rocks

Unit symbol: MDtv
Age range Mississippian? to Devonian (419.2 to 323.2 Ma)
Lithology: Metamorphic
Group name: Volcanic rocks and sills
Consists of sheared, schistose, green andesitic tuff and volcanic breccia which weathers yellow and orange and altered to chlorite, epidote, clinopyroxene, and clay (Brosgé and others, 2000) in the northeast Arctic and northwest Table Mountain quadrangles. Also includes crystal and lithic tuff, volcanic breccia, and minor porphyry of rhyolitic composition, now mostly recrystallized to fine crystalline quartz-sericite schist (Brosgé and others, 2000; C.G. Mull, unpub. data). Associated with Mississippian rocks of the Lisburne Group and the Kekiktuk Conglomerate (units IPMlg and Mek), as well as the Mississippian and Devonian Endicott Group (unit MDe), but is distinct from similar rocks in the southwest Arctic quadrangle and farther west in the Brooks Range, which are associated with Devonian rocks (units Das and Dv). Age control is lacking

Source map information

Source map Mull, C.G., and Sonneman, H.S., 1968-1974, Unpublished data
Symbol Pzv
Unit name Rhyolitic volcanic rocks
Description Schistose rhyolitic volcanic rocks in Double Mountain area, possibly coeval with Mkkv in upper Sheenjek River area. In NW corner of quadrangle, upper Sheenjek River area. Autochthonous/parautochthonous structural unit
Lithology Igneous

Correlated geologic units

Label Dvr
Description Metamorphosed sills, dikes, and flows of andesite to rhyolite composition
Geologic age Devonian to Mississippian
Geologic setting Extrusive
Lithology Form Importance
Metaandesite < Metavolcanic < Metaigneous < Metamorphic Greenschist Indeterminate, major
Metadacite < Metavolcanic < Metaigneous < Metamorphic Greenschist Indeterminate, major
Metarhyolite < Metavolcanic < Metaigneous < Metamorphic Greenschist Indeterminate, major