Evolución Metamórfica y Anatexia en el núcleo de Lora del Río (Zona de Ossa-Morena)

Abstract

The Lora del Río metamorphic core crops out in the central-southern area of the Ossa-Morena Zone (OMZ), in the southeastern prolongation of the Monesterio antiform. lt is constituted by a monotonous metapelitic succession with interbedded layers of amphibolites and calc-silicate rocks. This succession is separated from the overlying Huéznar Series by tectonic contacts. The latter has a tectonic relation with the Capas de Tambor succession (Simón, 1951), which has been attributed to the early Cambrian and has been correlated with the Torreárboles Formation (Liñán, 1978). The Lora del Río core exhibits evidences of two majar metamorphic events. The second one, a low pressure/high temperature episode, is prevailing. lt erases almost, all of the remants of the previous, barrovian type, metamorphic event. A metamorphic zonation characterized by the progresive occurrence of biotite, andalusite, sillimanite-muscovite, sillimanite-Kfeldspar, and cordierite-Kfeldspar±garnet has been established for the second episode. Pressure and temperature conditions of equilibrium of the highestgrade metamorphic assemblages have been calculated by the use of different geothermometers and geobarometers. The results obtained together with considerations concerning the time evolution of mineral parageneses, enable lis to reconstruct a clockwise PTt path. The resulting metamorphic evolution has been interpreted in relation to initial intermediate pressure metamorphic field gradients later evolving into the low pressure PT-field at the same time that uplift and unroofing mechanisms are set on.