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South America and Southern Africa
The Malvinokaffric Realm in the Devonian of Brazil
Paleogeographic reconstructions are presented for the Lower and Middle Devonian of Brazil (Siegenian — Givetian), following a brief account of Brazilian Devonian stratigraphy and biogeography. Compiled sedimentologic, lithostratigraphic, biostratigraphic and biogeographic data relevant to the reconstructions are discussed in the text. The poorly known Upper Devonian of Brazil records times of post-Malvinokaffric faunal cosmopolitanism and is therefore excluded from the main scope of this paper. In general, comparison of transgressive-regressive patterns in all three major Devonian basins of Brazil reveals mutual correspondence of deepening events. The main exceptions are the Givetian and younger sections of the southern Parana Basin and eastern Parnaiba Basin where the effects of regional tectonics and progradation were dominant. Correlation of such patterns with potential equivalents in the global Devonian sea-level curves is only tentative due to the overall lack of conodont-based biostratigraphic support in the Malvinokaffric areas. Increasing onlap is observed in the Brazilian marine basins from Emsian through the Frasnian, thus in agreement with general patterns predicted from the global Devonian sea-level curves. Vanishing Malvinokaffric provincialism in the Givetian along with the appearance of distinctive “boreal” forms in the Devonian seas of South America and South Africa is related to climatic changes brought about by the combined effect of incoming warm marine currents from the north and successive sea-level rises.
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