Thermobarometry and P-T path of metasedimentary rocks of the araxá group from goiás

Abstract

In the southeastern region of Goiás state (Caldas Novas - Morrinhos - Rochedo region) outcrop psammitic, psamo-pelitic and pelitic metasediments related to the Araxá Group. In the Caldas Novas region (Caldas Novas Domain), the mineral associations related to the metamorphic peak are typical of the upper greenschist facies/lower amphibolite facies and the calculated metamorphic peak indicates temperatures between 500°C and 570°C and pressures between 7-8 kbar, kyanite zone. The mineral associations related to the metamorphic peak in the region between Marcelândia - Morrinhos - Rochedo (Araxá West Domain) are typical of medium to upper amphibolite facies and the thermobarometric calculations show metamorphic peak at 600°C - 670°C and 9-11 kbar, under conditions of amphibolite facies, kyanite zone. The calculations with the geothermometer Zr-in-Rt, performed for pressures of 10 kbar, indicate a minimum temperature of 527°C and a maximum of 688°C. The P-T path, inferred based on textural and thermobarometric data, is clockwise. The mineral associations observed in congruence with mineral chemistry analyzes and thermobarometric studies suggest a progressive metamorphic zoning from E to W in the Araxá Group in the Caldas Novas - Morrinhos - Rochedo region. However, the thermobarometric data suggest that the sets have different metamorphic histories and that metamorphic zoning is a result of tectonic structuring.