Undivided granitic rocks

Unit symbol: Tpgr
Age range Tertiary, late Paleocene (66 to 56 Ma)
Lithology: Igneous - Plutonic
Group name: Granitic rocks of southern and interior Alaska
Predominantly medium-grained composite plutons of granite and quartz monzonite and lesser granodiorite and quartz syenite. Biotite is the chief mafic mineral and hornblende is locally present, especially in the granodiorite phases. Muscovite is a common component of the granite. Unit is widespread, although the bulk of the exposure is in the western Alaska Range and Tyonek quadrangle or spatially associated with the Alaska-Aleutian Range batholith of Reed and Lanphere (1973) in the Lake Clark and Iliamna quadrangles. It is primarily distinguished from unit Tkg by age determinations. Unit includes the Styx River batholith of Reed and Elliott (1970), rocks of map units Ti7, Ti10, and Ti11 of Nelson and others (1983), much of the McKinley series of Reed and Nelson (1980) and unit Tbgd of Csejtey and others (1978). Outliers occur in Unalakleet and Table Mountain quadrangles. In the Lime Hills and western Tyonek quadrangles, it is difficult to distinguish between this map unit and unit TKg; without additional mapping and data, the density of lithologically similar plutons makes distinction of these two units especially difficult

Source map information

Source map Csejtey, Bela, Jr., Mullen, M.W., Cox, D.P., and Stricker, G.D., 1992, Geology and geochronology of the Healy quadrangle, south-central Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-1961, 63 p., 2 sheets, scale 1:250,000.
Symbol Tgr
Unit name Granitic rocks
Description Wide variety of epizonal granitic rocks, most commonly granite and granodiorite but including tonalite and quartz monzodiorite. Either through dates or position, these appear to be the Paleocene of the granitic rocks (FHW)
Lithology Igneous

Correlated geologic units

Label Tpg
Description Granitic rocks, ranging from granite to granodiorite, mostly felsic
Geologic age Paleocene
Geologic setting Intrusive, granite
Lithology Form Importance
Granite < Granitic < Plutonic < Igneous Pluton Major
Quartz-monzonite < Syenitic < Plutonic < Igneous Pluton Minor
Syenite < Syenitic < Plutonic < Igneous Pluton Minor