Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Golden Horn

stripes

Occurrence number: 
174-00-013
Country: 
United States
Region: 
Washington
Location: 
Longitude: -120.75, Latitude: 48.58
Carbonatite: 
No

The Golden Horn batholith is an approximately rectangular intrusion of 37x11 km in the Northern Cascades (Misch, 1966, Plate 7-1). The rocks are generally leucocratic and include a peralkaline granite and biotite granites. The peralkaline granite contains perthite, sodic amphiboles, sometimes aegirine, minor biotite and accessory fluorite, magnetite, zircon, apatite and carbonate. Stull (1973) distinguishes three types of alkaline amphibole; euhedral, early arfvedsonite, subhedral osannite and late riebeckite which is commonly found in miarolitic cavities.

Age: 
Age: determinations on biotite by Kulp and Curtis (in Misch, 1966, p. 139) give an age near the Eocene-Oligocene boundary.
References: 

MISCH, P. 1966. Tectonic evolution of the northern Cascades of Washington State: West-Cordilleran case history. In Tectonic history and mineral deposits of the western Cordillera. Special Volume, Canadian Institute of Mining and Metallurgy, 8: 101-48.
STULL, R.J. 1973. Calcic and alkali amphiboles from the Golden Horn batholith, North Cascades, Washington. American Mineralogist, 58: 873-8

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith