Magmatic reorption versus subssolidus metasomatism--two different styles of K-feldspar replacement of plagioclase

Comparisons of mineral textures in the orthoclase-bearing, copper-porphyry, quartz monzonite Cornelia pluton in Arizona (Wadsworth, 1968) with mineral textures in the microcline-bearing Rocky Hill granodiorite stock in California (Putnam and Alfors, 1969, 1975) reveal two different styles of K-feldspar replacement of plagioclase. The first is by above-solidus magmatic resorption; the second is by subsolidus K-metasomatism. The differences in styles of replacement raise doubts about the common perception among petrologists that all K-feldspar replacements of plagioclase in granite plutons are by magmatic resorption (e.g., Hogan, 1993).