Geochemistry and U-Pb zircon ages of plutonic rocks from the Algodoes granite-greenstone terrane, Troia Massif, northern Borborema Province, Brazil: Implications for Paleoproterozoic subduction-accretion processes

摘要

The Algodoes metavolcano-sedimentary sequence is located at the northern margin of the Archean/ Paleoproterozoic Troia Massif, northern Borborema Province (NE Brazil). It represents a well-preserved Paleoproterozoic greenstone-like sequence affected by two major plutonic events. The early plutonism, represented by the Cipo orthogneisses, mainly comprises biotite-bearing metatonalites, which share similar geochemical signatures with Archean tonalite-trondjhemite-granodiorite ('ITG). For these rocks, we report U-Pb (LA-ICPMS) zircon ages of 2189 +/- 14 Ma and 2180 +/- 15 Ma. A subsequent plutonic magmatism occurred at similar to 2150-2130 Ma and is mainly represented by hornblende-bearing dioritic to tonalitic orthogneisses of the Madalena Suite and Sao Jose da Macaoca Complex. Geochemical data indicate that these dioritic/tonalitic orthogneisses have adakitic characteristics and strongly suggest mantle-related magmas. A (sensu stricto) granite plutonism (Serra da Palha orthogneisses) also intruded the Algodoes sequence and yielded U Pb (LA-ICPMS) zircon age of 2150 +/- 16 Ma. These granitic orthogneisses show high-IC content, A-type characteristics and probably derived from partial melting of a crustal (tonalitic) source. We suggest that the early similar to 2190-2160 Ma TTG plutons probably developed in intra-oceanic arc setting, whereas the following similar to 2150-2130 Ma adakitic plutons and A-type granitic magmatism developed in response to arc-continent collision. (C) 2015 Elsevier Ltd. All rights reserved.