Basalt and red beds member (Tindir Group)

Unit symbol: Pxtnm
Age range Proterozoic (1600 to 541 Ma)
Lithology: Igneous - Volcanic
Group name: Basalt and red beds member (Tindir Group) and Mount Copleston volcanic rocks of Moore (1987)
Dark-greenish-gray basalt, commonly amygdaloidal and displaying pillow structures; unit ranges from 90 m to at least 750 m thick in the Charley River and Eagle quadrangles. Feldspar and pyroxene are mainly unaltered but, at a few localities, are chloritized and rock is greenstone. Minor basaltic tuff contains pebbles and cobbles of basalt. Red beds mostly grayish-red shale and siliceous shale. Minor greenish-gray shale and siliceous shale, jasper, greenstone-dolostone conglomerate, hematitic doloarenite, vitric tuff, and some occurrences of basalt have been largely replaced by hematite and carbonate (Brabb and Churkin, 1969). Similar rocks are also found in the Mount Michelson (Robinson and others, 1989) and Demarcation Point quadrangles (Reiser and others, 1980)

Source map information

Correlated geologic units

Label Ytb
Description Upper Tindir Group, basalt and red beds member
Geologic age Mesoproterozoic to Neoproterozoic
Geologic setting Sedimentary, continental
Lithology Form Importance
Basalt < Mafic-volcanic < Volcanic < Igneous Flow Major
Mafic-volcanic < Volcanic < Igneous Pyroclastic, tuff Indeterminate, major
Conglomerate-mudstone < Mixed-clastic < Clastic < Sedimentary Bed Minor