Volcanic rocks and sills associated with Lisburne Group

Unit symbol: Clgv
Age range Pennsylvanian? and Mississippian (358.9 to 298.9 Ma)
Lithology: Igneous - Volcanic
Group name: Volcanic rocks and sills
Typically, consists predominantly of light-gray to green-gray, light-brown to rusty-weathering felsic tuff that has abundant feldspar and sparse biotite phenocrysts; typically has calcareous cement and disseminated sulfide minerals. Tuff is associated with tuffaceous sandstone, coarse-grained limestone that contains disseminated light-green chloritic minerals, and thick-bedded to massive calcareous rocks that contain volcanic fragments (Dover and others, 2004). In the Baird Mountains quadrangle, unit is orange-, tan-, or light-brown-weathering, thinly laminated limestone, tuff, and volcaniclastic rocks with subordinate sills and plugs of intermediate to mafic composition; unit contains conodonts of early Early Mississippian age (Karl and others, 1989a). Elsewhere unit has been shown to contain conodonts of latest Late Mississippian age (Brosgé and others, 2001). Where unit is known as sills, the sills are generally chloritized andesite. Most typically associated with the Lisburne Group, similar volcaniclastic rocks range from agglomerate to tuff of felsic to intermediate composition and are associated with the Kayak Shale in the Howard Pass quadrangle. Like the exposures in the Baird Mountains quadrangle, these volcaniclastic rocks contain conodonts of early Early Mississippian age. In the Table Mountains quadrangle rhyolitic volcanic rocks are interbedded with the Kekiktuk Conglomerate of Early Mississippian age. Typically associated with the Endicott Mountains allochthon, these volcanic rocks are also known from rocks of the autochthonous North Slope of Alaska

Source map information

Source map Curtis, S.M., Ellersieck, Inyo, Mayfield, C.F., and Tailleur, I.L., 1984, Reconnaissance geologic map of southwestern Misheguk Mountain quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Map I-1502, 2 sheets, scale 1:63,360.
Symbol IPMv1
Unit name Felsic Volcanic Rocks
Description Part of the Key Creek Sequence - Includes hypabyssal intrusive rocks. Biotite latite or andesite in exposures west of Nimiuktuk River (southeastern Misheguk Mountain quadrangle map); porphyritic biotite latite and tuffaceous sedimentary rocks west of Kugururok River (southwestern Misheguk quadrangle map). In uncertain stratigraphic position but probably in upper part or top of the Kuna Formation. Potassium-argon date from biotite in volcanic rocks near Nimiuktuk River 333+/-17 m.y. (Mayfield and others, 1979).
Lithology Igneous

Correlated geologic units

Label Mv
Description Volcanic rocks and sills associated with Lisburne Group
Geologic age Carboniferous
Geologic setting Extrusive
Lithology Form Importance
Felsic-volcanic < Volcanic < Igneous Pyroclastic, tuff Major
Andesite < Mafic-volcanic < Volcanic < Igneous Flow Major
Greenstone < Metaigneous < Metamorphic Major
Latite < Felsic-volcanic < Volcanic < Igneous Flow Indeterminate, major