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

• Two major plutonic events can be distinguished in the Paleoproterozoic Algodões granite-greenstone terrane.
• The plutonic rocks evolved from early (2190–2160 Ma) trondhjemites to late (2150–2130 Ma) adakitic plutons and A-type granites.
• Change in magmatism probably occurred in response to intra-oceanic arc accretion to a continental margin.

The Algodões 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 Cipó orthogneisses, mainly comprises biotite-bearing metatonalites, which share similar geochemical signatures with Archean tonalite-trondjhemite-granodiorite (TTG). 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 ∼2150–2130 Ma and is mainly represented by hornblende-bearing dioritic to tonalitic orthogneisses of the Madalena Suite and São José 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 Algodões sequence and yielded U–Pb (LA-ICPMS) zircon age of 2150 ± 16 Ma. These granitic orthogneisses show high-K content, A-type characteristics and probably derived from partial melting of a crustal (tonalitic) source. We suggest that the early ∼2190–2160 Ma TTG plutons probably developed in intra-oceanic arc setting, whereas the following ∼2150–2130 Ma adakitic plutons and A-type granitic magmatism developed in response to arc-continent collision.