DISEQUILIBRIUM PROCESSES ALONG GRADIENTS IN EARTH'S GRAVITATIONAL FIELD

Abstract

Irreversible thermodynamics treat disequilibria in Earth's open systems, gravitational fields, and gradients in temperature, pressure, and composition. Equilibrium studies on closed systems lack gradients and apply most closely to phase events in restricted volumes of the Earth. Liquid silicates are governed by rules of solution chemistry: solubilities of phases, chemical potentials of components, and kinetics of irreversible reactions. Magma bodies enter the crust physically by penetration of diapirs along zones of structural weakness, and passively, by chemical replacement of country rocks. Chemical mechanisms based on irreversible principles are Ortolevan reaction cells that rise in gravitational fields by cycling excess energies of liquefaction between endothermic dissolution at cell tops and exothermic precipitation at cell bases; released energies migrate upward in central liquid zones. Cells that halt within the crust produce passively emplaced plutonic intrusives; those that penetrate to the surface form volcanic fields genetically associated with intrusives below.