Replacement origin of the albite granite near Sparta, Oregon

Abstract

The albite granite near Sparta, in the foothills of the Wallowa Mountains of eastern Oregon, is thought to be a product of albitization and partial silicification of an earlier' quartz diorite. These changes are attributed to late magmatic and postmagmatic replacement of the almost completely solidified quartz diorite by solutions derived probably through filter pressing from lower portions of the same mass. These solutions were guided, at least in part and probably entirely, by brecciated zones in the quartz diorite.