The Cloudy Pass epizonal batholith and associated subvolcanic rocks
The Cloudy Pass epizonal batholith and associated subvolcanic rocks
Special Paper - Geological Society of America (1969): 54 pp.
The Cloudy Pass batholith, consisting largely of labradorite granodiorite, discordantly intrudes pre-Late Cretaceous rocks in north-central Washington. The small batholith is remarkable for its chilled borders, associated porphyry plugs, and intrusive breccias. It is bordered on the northeast by the 1.5-mi-thick chilled complex of Hart Lake that consists of separately injected, contrasting layers of dacite and labradorite-bytownite andesite porphyries and autobreccias. Porphyry plugs, largely dacite, puncture the adjacent metamorphic rocks. Intrusive breccias are of two types, one confined to the core of the batholith, the other, apparently injected explosively, confined to the porphyry plugs and gneiss. Plagioclases range from high- to low-temperature; the low-temperature form, in the batholith core and in the complex, is thought to have inverted from original high-temperature.