High and Low-Ti Tholeiites in the Eastern Parnaíba Basin: Regional Correlations with Mesozoic Large Igneous Provinces

High and Low-Ti Tholeiites in the Eastern Parnaíba Basin (Brazil): Regional Correlations with Mesozoic Large Igneous Provinces

Two tholeiitic magmatic events are recorded at the eastern border of the Parnaíba Basin, comprising the Mosquito and Sardinha Formations. These events are chronocorrelated with the Central Atlantic Magmatic Province (CAMP LIP) and the Equatorial Atlantic Magmatic Province (EQUAMP LIP), respectively. The latter is also chronocorrelated with the Paraná-Etendeka Magmatic Province (PEMP LIP). Five groups of tholeiitic rocks are representative of magmatic episodes with different ages and tectono-magmatic contexts: Low-Ti Group I, High-Ti Group IIa, High-Ti Group IIb, High-Ti Group III, and High-Ti Group IV. Geochemical data for Groups I, IIa, and IIb are similar to tholeiitic basalts from the Jurassic CAMP LIP, whereas rocks in Groups III and IV can be related to the Cretaceous EQUAMP LIP as well as the high-Ti basalts of the PEMP LIP. The chemical differences between the two magmatic events indicate changes in the mantle composition underlying the Parnaíba Basin over geological time. It is likely that the Brasiliano-Pan African orogenies, which preceded Jurassic rifting, affected the mantle sources of the Groups I and II magmas. Conversely, the composition of the mantle underlying the Parnaíba Basin was modified by the impingement of a mantle plume during the Cretaceous

Keywords: Sardinha and Mosquito Formations, continental flood basalt, deep mantle plume, Central Atlantic Magmatic Province