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ESTRATIGRAFIA DE SEQUÊNCIAS DAS FORMAÇÕES CAMPO MOURÃO (PARTE SUPERIOR) E TACIBA, GRUPO ITARARÉ, LESTE DA BACIA DO PARANÁ

1999; Sociedade Brasileira de Geologia; Volume: 29; Issue: 2 Linguagem: Inglês

10.25249/0375-7536.199929255260

2177-4382

Joel Carneiro de Castro,

Fish biology, ecology, and behavior

The chronostratigraphic framework of the Campo Mourão (upper part) and Taciba formations, Itararé Group was investigated through a subsurface study in the eastern flank of the Paraná Basin. A total of five depositional sequences were recognized, each represented by an upward increase in the argillaceous content (sandstone to diamictite to shale). The upper part of basal sequence 1 is formed by a thick diamictite overlain by the Lontras Shale; these glaciomarine and marine systems may constitute the transgressive tract of the sequence and represent the top of Campo Mourão Formation/cycle. The Lontras Shale (or Member) is not restricted to the Santa Catarina State; instead it is recognized throughout the eastern flank of the basin. The sequence 2 is represented in the basal portion by the sandstones of Rio Segredo Member (base of Taciba Formation/cycle). The next sequences are similar to the previous one, including some particular patterns: as the basal sandstones form clastic wedges, the sequence may be represented exclusively by diamictites. The clastic wedges of sequences 2 and 4 were supplied from east and northeast; the western margin also contributed as source of coarse elastics. Sequences 4 and 5 were studied in detail, since they were reached by several shallow wells near the outcrop belt. The sequence 4 clearly displays facies change from marine in the south (Passinho Shale) to delta front in center-south, and to coal-bearing delta plain in the north. The occurrence of sequence 5 is restricted to southern Paraná and northern Santa Catarina; it presents deltaic sandstone deposits intercalated with marine shales/sandstones and glaciomarine diamictites. Despite some transitional characteristics shown by the upper part of Itararé Group (sequences 4 and 5), it is noteworthy the unconformable relationship of the Group with the overlying, post-glacial Triunfo Member of Rio Bonito Formation.