Syenitic rocks

Unit symbol: Ksy
Age range Cretaceous, Coniacian to Albian (113 to 86.3 Ma)
Lithology: Igneous - Plutonic
Group name: Granitic rocks of central and southeast Alaska
Nepheline syenite, syenite, monzonite, and subordinate alkaline plutonic rocks and dikes including malignite, ijolite, shonkinite, and pyroxenite (Patton and Miller, 1968). Part of the “western Yukon-Koyukuk plutonic suite” of Miller (1989), a potassic and ultrapotassic belt that outcrops from the northeast corner of the Bettles quadrangle to Saint Lawrence Island. K/Ar and 40Ar/39Ar ages range from about 95 to 113 Ma with the majority of ages between 105 and 109 Ma

Source map information

Source map Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, 2009, Geologic map of the Yukon-Koyukuk basin, Alaska: U.S. Geological Survey Scientific Investigations Map SIM-2909, 26 p., 2 sheets, scale 1:500,000.
Symbol Ksy
Unit name Granitic rocks
Description Granitic rocks of hornblende and pyroxene monzonite and syenite. Minor biotite quartz monzonite. Unit subdivided by Patton (1999, 2000)
Lithology Igneous

Correlated geologic units

Label Ksy
Description Syenite
Geologic age Albian to Santonian
Geologic setting Intrusive
Lithology Form Importance
Monzonite < Syenitic < Plutonic < Igneous Pluton Major
Syenite < Syenitic < Plutonic < Igneous Pluton Major