Diagenesis of the sandstrones in Rift Tectonossequence of Araripe Basin, NE Brazil

The Araripe Basin is the largest interior basin in the Northeastern Brazil, with a more complex geological history. The studied interval corresponds to the Missão Velha and Abaiara formations, cropping out in the central-west Valley Cariri. To subsidize the studies of diagenesis and provenance, a facies analysis was performed which identified ten sedimentary facies according to different lithologies and main sedimentary structures. The petrographic study allowed classifying the lithotypes as quartzites, which present grains of quartz, feldspars and rock fragment sand, subordinately, heavy minerals. The diagenetic history was characterized by a variety of phases that occured during the stages of eo-, meso- and telodiagenesis. The eodiagenetic stage is marked by mechanical infiltration of clays and the beggining of mechanical compaction. The mesodiagenetic stage is characterized by the end of mechanical compaction, chemical compaction, quartz and feldspar overgrowths, calcite cementation, dissolution, authigenic kaolinite formation, alteration of grains to chlorite and illite, and the precipitation of opaque minerals. Telodiagenetic stage is evidenced by the oxidation of grains, matrix and cement present. This information allowed a comparative study of the formations.

Araripe Basin; diagenesis; Rift