The Borborema Province (BP) of northeastern Brazil is a complex crustal assemblage, which has undergone a polycyclic evolution during the Proterozoic. In the Piancó-Alto Bŕgida belt, a metamorphosed leucosome vein inserted in amphibolites has a trace element pattern suggesting a T-MORB protolith. Apatites yield a REE pattern indicating growth in equilibrium with garnet, thus pointing to its metamorphic origin. U-Pb analyses yield an age of 540 ±5 Ma interpreted as a cooling age following amphibolite facies regional metamorphism associated with granitic emplacement at ca. 580 Ma. The resulting slow cooling rates (ranging from ca. 2.5 to 5 °C Ma-1) are consistent with underplating of mafic magmas, or crustal thickening caused by nappe stacking, as possible processes governing the metamorphic evolution of the BP.
|Translated title of the contribution||An Early-Cambrian U-Pb apatite cooling age for the high-temperature regional metamorphism in the Piancó area, Borborema Province (NE Brazil): Initial conclusions|
|Number of pages||9|
|Journal||Comptes Rendus Géoscience|
|Publication status||Published - 1 Jan 2003|
- Borborema Province
- Cooling age
- U-Pb dating