Petrophysics and thermal aureole provoked by the tororó Pluton into micashits of the seriade formation,RN
Plutonism; Thermal aureole; Neoproterozoic; Borborema Province; NE Brazil
The northeastern of Borborema Province is marked by a massive Neoproterozoic plutonism of basic to acid composition, intrusive into metasupracrustal rocks of Seridó Group. In this context, the Totoró pluton, NW of Currais Novos / RN, is associated laterally to the SSW-NNE Serra Seriema shear zone. It is composed of basic to intermediate rocks, mainly equigranular to porphyritic biotite granites, with leucogabbros-norites and diorites enclaves. Geological mapping and microscopic analysis allowed visualizing a significant mineralogical variation in micaschists country rocks at different distances from the contact of the intrusion. This is reflected in metamorphic parageneses portarying different proportions of cordierite, andalusite, sillimanite and garnet, besides migmatized micaschists with relicts of paleosome and leucosomes of trondhjemitic composition, wich characterizes a metamorphic aurole that can extend until 2 km from the contact. Thermobarometric results showed that the emplacement temperature of pluton varied of the 800-900ºC under pressures of 4.7-5.2 kb. Modelling based on rock conductivity revealed that the temperature at the pluton contact reached 688-756 degrees Celsius and the heat could remain at about 500 degrees Celsius until 1800 m from a time span of 365.000 years.