Provenance analysis of the Araripe intracontinental basin, northeast Brazil – Routes for proto-Atlantic marine incursions in northwest Gondwana

Abstract

This study presents U-Pb dating of detrital zircons from sandstones of the Araripe basin (NE Brazil) assisting in the reconstruction of the Mesozoic paleogeography. In particular, we focus in the seaway connection between the Proto-Atlantic ocean and this intracontinental basin in northwest Gondwana.The new U-Pb age spectra of detrital zircon grains from the pre-Jurassic and Mesozoic clastic sequences of the Araripe Basin, along with paleocurrent, stratigraphic and structural data, demonstrate a significant change in provenance during the Later Jurassic to mid-Cretaceous. Six distinct provenance patterns are identified in the sequences, which may reflect the rapid evolution of the paleogeographic scenarios during tectono-sedimentary history of the northwest Gondwana rift-related basins throughout the onset to the opening of the Atlantic Ocean. Here, we propose an alternative model for paleogeography of the northwest Gondwana. In the Later Jurassic, the main source of terrigenous clastics to the Araripe Basin was the Paleozoic-Triassic sedimentary rocks of the Parnaíba Basin, which formed a prominent barrier to separate the Araripe Basin from the Mesozoic units of the Parnaíba Basin. In the mid-Aptian, erosion led to the retraction of the Parnaíba Paleozoic sedimentary units to the west, as the Precambrian terranes from the Borborema Province, to the northwest, became the main source for the Araripe Basin. The rapid rifting evolution show that the Rio Salgado Belt, from NE region, became topographically depressed, potentially initiating a link between the Araripe and the Potiguar basins. During late-Aptian, the Araripe Basin probably connected to the Proto-Equatorial Atlantic Ocean from the northeast, through the Potiguar Basin and associated grabens on the north. The present paleogeographical reconstruction may explain the occurrence of warm water adapted Tethyan fauna in the Araripe Basin, more plausible than previous hypothesis of a connection to Proto-South Atlantic Ocean.