Published: Feb 1997
Pages: 3 - 10
Authors: GIUSEPPE LUCIDO
Abstract: At Orcoyana, in the Soto region (Argentina), two types of cordieritic rocks outcrop: a light variety and a dark variety. Both of these contain, in very different quantities, very peculiar structures considered in literature as porphyroblasts. In order to gain insight into their origin, a petrologic and geochemical study was carried out. In the light of the new ordering principle, called "order through fluctuation", we applied the basic principles of self-organization dynamics to the Argentine structures. They appear to have "self-organized" as colloidal dissipative structures which formed in a self-organizing basic fluid. According to us, the origin of the Argentine structures involved a phase separation process ensuing from spontaneous density fluctuations in critical conditions. As the phase separation proceeded the fluid comprised immiscible portions in a state of emulsion. When the segregated phase was very concentrated, the Argentine fluid exhibited three distinguishable phases. From a thermodynamic point of view, there was a three-phase system, like a vesicle, with an interior, barrier and exterior.
Keywords: Argentina, self-organization, cordierite-rocks, structural charactersDownload PDF document