Estudio de la influencia térmica del emplazamiento de doleritas (ofitas) del área de Estopiñán (Huesca-Lérida) en los sedimentos triásicos encajantes.

Abstract

In Ihe Estopiñan area (Huesca and Lérida> Spanish Pyrenees> Ihere are numerous silís of triassic dolerites (ophites) in which fluidal slructures had been observed (LAGO & POCOVI, 1982> and whose intrusion happened under a reduced sheet of sedimenís in the Upper Trias (LAGO & POCOVI, 1982). In this work the minera] associations are studied in the chilled margins of the dolerite and in the nearer sediments of the host rock, wiíh special emphasis to the clay fraction. The temperature of crystallization of the dolerite belongs to the rank 1200-7500C (AMIGO & LAGO, 1985). Mineral associations in the chilled margin suggesís temperatures from 500 to 4OmC. In the chilled margin and in Ihe nearer sediments talc has been observed, the reaction proposed for producing talc is consistení with temperatures for the chilled margin. The initial hydrothermal rnetamorphic associations are probably masked by subsequent hydrothermal events. The expandables sheeí silicates observed are compatible with a wide rank of temperature (up to 75~C> but their preservation oul of hydrothermal conditions suggests shallow burial conditions.