Fig. 5: Geological map with structural sketch of the Guyana Shield8.
From: Large-scale crustal growth driven by LIP magmatism during the Paleoproterozoic
TTG and greenstone belts constitute approximately 75% of outcropping Rhyacian crust. The remaining 25% corresponds to granitic magmatism, in part Mg-potassic, charnockites, and arc-related dioritic to tonalitic granitoids and gneisses. Late-Rhyacian and Early-Orosirian rocks comprise UHT granulites, charnockites, and high T/P metamorphic rocks partially contemporaneous with the magmatism associated with Cycle 1, marking an increase in silica and incompatible elements in outcropping crust. The following stages are the emplacement of Cycle 2 igneous rocks and the deposition of the continental Roraima Basin, which is intruded by dykes and sills from the Avanavero LIP, correlated to Cycle 3.
