GRANITES BY REPLACEMENT FAR FROM EQUILIBRIUM BY REACTION CELLS; GRANITIC MINERALS MODIFIED TO PORPHYROBLASTS OF ORTHOCLASE AND QUARTZ NEAR TO EQUILIBRIUM BY STRESS

Self-organized replacement takes place in systems with excess energy that may be near to or far from equilibrium (NTE or FFE). FFE reactions are unpredictable but can be followed experimentally (Prigogine, 1997). NTE perturbations in linear range of disequilibria return to equilibrium by laws of physics and chemistry (Onsager, 1931). NTE principles apply to geochemical problems (Ortoleva, 1994). Reaction cells under FFE conditions cycle excess energy of liquefaction in dissolving and precipitating minerals in temperature-pressure (TP) gradients of gravitational fields. Deep plutons with TP conditions close to surroundings can not quench. To solidify, excess energies must be disposed of. Vertical bodies sustain gradient of TP, which control solubilities of minerals (Dickson and Hsu, 2000). Minerals of cover rocks dissolve endothermically at cell tops, regardless of type. Minerals precipitate exothermically at cell bases. Fugitive components tend to fractionate to liquids. Released energies migrate upward by convective overturn. Passive replacement of country rocks emplaces intrusive bodies such as granite. Dickson (1996) documented effects of stress on the newly emplaced quartz monzonite pluton at Papoose Flat, Inyo Mtns., Calif., under NTE conditions. Megacrystals of monoclinic orthoclase, with metamorphic textures and crooked shapes, and quartz bipyramids, replaced original igneous minerals, including quartz and orthoclase in groundmass. This association occurs in western U. S., Europe and Asia, and is probably world-wide. Sustained energy of stress destabilizes host minerals at surfaces, which discharge elements to intergranular fluids. Orthoclase and quartz crystals nucleate and grow, and release excess energy that destabilize matrix minerals regardless of identity. Stress energies cycle in replacement reactions.