Metamorphic conditions in the Coastal-Punta del Este Terrane of the Kaoko-Dom Feliciano Belt in Namibia and Uruguay

Abstract

The metasediementary rocks of the Coastal Terrane in the Kaoko Belt (Namibia) and the meta-igneous rocks of the Punta del Este-Terrane in the Dom Feliciano Belt (Uruguay) both share one high-grade metamorphic event at approximately the same time of c. 650-630 Ma. Metamorphic conditions of this high-grade event were estimated in four samples from the Punta del Este Terrane and two samples from the Kaoko Belt. The P-T conditions recorded in the Punta del Este Terrane yielded temperatures of c. 830-860°C and pressure of c. 7,5-10,5 kbar in one sample, whereas other two gave temperatures of c. 630-800°C and pressure of c. 3,0-4,5 kbar. One sample suggests temperatures of c. 780-790C and pressures lower than 2,8 kbar. The samples from the Kaoko Belt yielded P-T conditions of c. 580-640 and c. 2,5-7,5 kbar. It was previously suggested that the Punta del Este Terrane in Uruguay and the Coastal Terrane in Namibia represent one tectonic unit dissected by the Atlantic Ocean. The P-T conditions of the samples from the Coastal Terrane indicate that this unit could represent its upper crustal part of the same tectonic unit as the middle- to lower-crustal samples from Punta del Este Terrane.