The Pernambuco-Alagoas (PE-AL) Domain contains major granitic batholiths typified by a wide range of T DM model ages (Archaean to Neoproterozoic), reflecting the important role of quartzofeldspathic plutons attending the Brasiliano (Pan-African) Orogeny. U/Pb zircon data for eight syn-to post-collision to syn-transcurrent granitic intrusions of the PE-AL Domain allow the studied plutons to be divided into two groups: (1) granitoids with crystallization ages older than 600 Ma (Água Branca, Serra do Catú, Serra da Caiçara, and Mata Grande plutons) and (2) granitoids with ages of ca. 590 Ma (Correntes, Águas Belas, Viçosa, and Cachoeirinha plutons). The intrusions of group 1, except for the Mata Grande Pluton, all show Nd T DM model ages ranging from 1.5 to 1.2 Ga, whereas the granitoids from group 2 and the Mata Grande Pluton have Nd T DM model ages ranging from 2.2 to 1.7 Ga. The studied granitoids are in part high-K, calc-alkaline, shoshonitic, and in part transitional high-K calc-alkaline to alkaline in terms of their bulk chemistry. Volcanic arc signatures associated with the Palaeoproterozoic T DM model ages are interpreted as inherited from the source rocks. The oldest ages and higher Nd T DM model ages recorded in the granitoids intruded in the southwestern part of the PE-AL Domain suggest that these intrusions are associated with slab-tearing during convergence between the PE-AL and Sergipano domains. The investigated plutons are coeval with high-K granitoids intruded within the Transversal Zone Domain of Borborema Province and calc-alkaline granitoids of the Sergipano Domain. This suggests that these geologic realms belonged to the same crustal block during the Brasiliano Orogeny. However, such large volumes of high-K granitoids with crystallization ages older than 600 Ma are not recorded in the Sergipano and Transversal Zone domains, suggesting differences in the crustal evolution of these three areas.
The studied syenogranite and granodiorite intrusions have a similar U-Pb zircon age (ca 570 Ma). They are intruded in the Central Tectonic Domain of the Borborema Province, forming an S-type belt in relation to the Patos and Pernambuco Lineaments. The studied granitoids are clinopyroxene biotite leuco-syenogranites of the Solidão Pluton; amphibole biotite sienogranites from the Queimadas Pluton; biotite granodiorite and amphibole biotite granodiorite, which occur as dikes cutting the Itapetim Complex and leuco-syenogranites from the Serra Branca Pluton. They show geochemical data transitional between shoshonitic and alkaline series. Deep troughs at Nb, Sr, P and Ti and high LILE/HFSE ratios characterize the spiderdiagram patterns. The ÎNd (0.6 Ga) values are extremely negative (-11 to -16; except for the Itapetim dykes ~-3) and Nd model ages (T DM ) range from 2.0 Ga to 2.5 Ga (the Itapetim dykes ~1.4Ga). Biotites of the studied granitoids are Fe-rich with Fe/(Fe+Mg) ratios in the 0.62 to 0.84 range. Biotites from older granitoids (640 Ma -580 Ma) of the Pajeú -Paraíba Terrane, have Fe/(Fe+Mg) ratios < 0.60. The isotopic and geochemical data suggest that the studied granitoids correspond to a trans-alkaline, ferro-potassic plutonism, originated by partial melting of Paleoproterozoic and Mesoproterozoic crusts, emplaced during the final stage of the Brasiliano Orogeny in the Central Tectonic Domain of the Borborema Province.
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