and may be related to a subaerial eruption. The dacitic body has an apparent dip
of approximately 20° to the east and unconformably overlies basaltic flows.
• Polymictic breccias: associated with rhyolite dykes throughout the deposit area.
The breccia zones most commonly occur in the footwall of the dykes, transitional to
host rocks. Breccias consist of angular rhyolite, obsidian, quartz vein and andesite
fragments in a dark, clay-rich felsic matrix. The breccias are irregular in outline (in
some cases pipe-like and/or conformable with contacts) and may represent
explosive breccia bodies or breccia; in part reflecting interaction of the rhyolitic
magma with groundwater.