Zircon geochronology of granitoids from the western Bacaja domain, southeastern Amazonian craton, Brazil: Neoarchean to Orosirian evolution

New zircon U-Pb SHRIMP and Pb-evaporation data on rocks from the west part of the Bacaja domain, southeastern Amazonian craton, reveal crustal evolution marked by a succession of magmatic events from Neoarchean to Orosirian. This domain represents the southern part of a geochronological province of the Amazonian craton that evolved during the Trans-Amazonian cycle (2.26-2.0 Ga). The earliest event is represented by inliers of ca. 2.67, 2.5 and 2.45 Ga orthogneisses and supracrustal rocks, followed by the formation of a 2.36-2.34 Ga granitoid-greenstone terrane and 2.31 Ga granitoids. Rhyacian granitoids and chamockitic rocks marked the main evolutionary stages of the Bacaja domain. Rhyacian magmatic events were distinguished in this domain: 2.21, 2.18, 2.16-2.15 and 2.13 Ga granitoids related to magmatic arcs of the Trans-Amazonian orogenies; 2.10-2.09 and 2.08-2.07 Ga granitoids and chamockitic rocks related to the post-collisional stage. A younger magmatic event at 1.99 Ga remains controversial, as it is uncertain whether this represents the last magmatic pulse of the Trans-Amazonian cycle or whether it is related to a younger cycle which affected the adjacent domain. Although Archean rock remnants have been found in Trans-Amazonian domains from South America, Siderian rocks are rare and distinguish the Bacajd domain from other Trans-Amazonian orogens of the Amazonian craton. (C) 2007 Elsevier B.V. All rights reserved. New zircon U-Pb SHRIMP and Pb-evaporation data on rocks from the west part of the Bacaja domain, southeastern Amazonian craton, reveal crustal evolution marked by a succession of magmatic events from Neoarchean to Orosirian. This domain represents the southern part of a geochronological province of the Amazonian craton that evolved during the Trans-Amazonian cycle (2.26-2.0 Ga). The earliest event is represented by inliers of ca. 2.67, 2.5 and 2.45 Ga orthogneisses and supracrustal rocks, followed by the formation of a 2.36-2.34 Ga granitoid-greenstone terrane and 2.31 Ga granitoids. Rhyacian granitoids and chamockitic rocks marked the main evolutionary stages of the Bacaja domain. Rhyacian magmatic events were distinguished in this domain: 2.21, 2.18, 2.16-2.15 and 2.13 Ga granitoids related to magmatic arcs of the Trans-Amazonian orogenies; 2.10-2.09 and 2.08-2.07 Ga granitoids and chamockitic rocks related to the post-collisional stage. A younger magmatic event at 1.99 Ga remains controversial, as it is uncertain whether this represents the last magmatic pulse of the Trans-Amazonian cycle or whether it is related to a younger cycle which affected the adjacent domain. Although Archean rock remnants have been found in Trans-Amazonian domains from South America, Siderian rocks are rare and distinguish the Bacajd domain from other Trans-Amazonian orogens of the Amazonian craton. (C) 2007 Elsevier B.V. All rights reserved. New zircon U-Pb SHRIMP and Pb-evaporation data on rocks from the west part of the Bacaja domain, southeastern Amazonian craton, reveal crustal evolution marked by a succession of magmatic events from Neoarchean to Orosirian. This domain represents the southern part of a geochronological province of the Amazonian craton that evolved during the Trans-Amazonian cycle (2.26-2.0 Ga). The earliest event is represented by inliers of ca. 2.67, 2.5 and 2.45 Ga orthogneisses and supracrustal rocks, followed by the formation of a 2.36-2.34 Ga granitoid-greenstone terrane and 2.31 Ga granitoids. Rhyacian granitoids and chamockitic rocks marked the main evolutionary stages of the Bacaja domain. Rhyacian magmatic events were distinguished in this domain: 2.21, 2.18, 2.16-2.15 and 2.13 Ga granitoids related to magmatic arcs of the Trans-Amazonian orogenies; 2.10-2.09 and 2.08-2.07 Ga granitoids and chamockitic rocks related to the post-collisional stage. A younger magmatic event at 1.99 Ga remains controversial, as it is uncertain whether this represents the last magmatic pulse of the Trans-Amazonian cycle or whether it is related to a younger cycle which affected the adjacent domain. Although Archean rock remnants have been found in Trans-Amazonian domains from South America, Siderian rocks are rare and distinguish the Bacajd domain from other Trans-Amazonian orogens of the Amazonian craton. (C) 2007 Elsevier B.V. All rights reserved.