The Sergipe-Alagoas Basin, northeastern Brazil, as a key for the paleogeographic understanding of the central Gondwana Carboniferous

Despite the increasing recognition of glaciations in Carboniferous Gondwana in recent years, there is a lack of detailed paleoclimatic and paleogeographic studies in central Gondwana. The Carboniferous successions of the Sergipe-Alagoas Basin, northeastern Brazil, presents significant geological features for understanding the sedimentary processes that occurred during this period. This study provides a paleogeographic interpretation for the Carboniferous of the Sergipe-Alagoas and adjacent basins, integrating lithostratigraphic data from boreholes and outcrops in the Carboniferous successions. The origin of this sequence was related to six glacial and interglacial paleoclimatic stages, reflecting the advance and retreat of glaciers. The first stage represented a glacial event, with extensive diamictite deposition, followed by four sequenced interglacial and glacial stages probably associated with a glaciolacustrine system, with the influence of rivers and deltas. The final stage represented the end of the glacial event and the reworking of previous deposits. The paleogeographic reconstruction proposed for the region consists of valleys controlled by Brasiliano age (Pan-African) mountain ranges, with a preferential NW–SE direction. Glacial valleys were delimited by the occurrence of diamictites from the Mulungu Member (Batinga Formation). In glacial periods, these valleys accommodated glaciers, while in interglacial periods, they were partly filled with water and became lakes. In the central portion of Gondwana, glaciation began in Visean (around 337 Ma), extending to the central east until Bashkirian (ca. 320 Ma). After this, the continents moved from the South Pole, and the ice began to melt. By the end of Sakmarian (around 290 Ma), their influences decreased considerably in this region. The age defined for the Batinga Formation, in the Sergipe-Alagoas Basin, suggests that the last glacial events in this portion of Gondwana occurred in the Westphalian.