Study of the West Gondwana Floras during the Late Paleozoic: A paleogeographic approach in the Paraná Basin – Brazil
Abstract The Late Paleozoic in West Gondwana was a period of significant climatic changes, ranging from a glacial climate in the Late Carboniferous to a semi-arid climate in the Late Permian. The Floristic Province of Gondwana in the Parana Basin was directly affected by such changes, and underwent a transformation regarding composition and geographic distribution. Thus, the climatic phases were divided into three intervals: Phase A containing interglacially developed flora; Phase B, containing floras of immediate post-glacial temperate climates, and phase C, identified with floras related to the decline of dryness. Regarding their geographical distribution, the floras were concentrated in the far-northern and far-southern portions of the basin during the Glacial interval, and, with a gradual increase in temperature, went on to occupy the entire basin. Finally, we can see that the floras located in the Argentinean portion of West Gondwana are older and have greater species diversity than those present in the Parana Basin and Africa during Phase A. In Phase B, there is a decline of Argentinean flora species, a large increase in the Parana Basin floras, and an average increase in African floras. In the final stage, the floristic province no longer exists in Argentina, the flora of the Parana Basin also suffers a decrease of specimens, and the African flora undergoes its moment of greatest development. Such diversity change also reflects a west-to-east migration throughout the Late Carboniferous.