PALEOECOLOGICAL CHARACTERIZATION OF OSTRACODS IN BEACHROCKS FROM THE NORTHERN SECTOR OF THE RIO GRANDE DO SUL COASTAL PLAIN, BRAZIL

A micropaleontological analysis on 15 beachrock samples from the Northern sector of Rio Grande do Sul Coastal Plain (RSCP), southern Brazil, revealed a relatively diverse and well-preserved ostracod assemblage composed of 16 species, including Cyprideis multidentata Hartmann, Callistocythere nucleoperiscum Whatley et al., Cytheretta punctata Sanguinetti, Caudites ohmerti Coimbra & Ornellas , and Argenticytheretta levipunctata Sanguinetti et al. Eleven ostracod species are left in open nomenclature or tentatively identified. Besides ostracods, some foraminifers, echinoderm spines, and fish remains (teeth) were also recovered; however, the scarcity of specimens or poor preservation precluded identification at species level. Based on the Ostracoda taxonomic composition it is proposed that the beachrocks characterize environmentally condensed assemblages. This preliminary study reveals the importance and potentiality of micropaleontology for understanding the processes involved in the formation of beachrocks.

Automated summary

A micropaleontological analysis of beachrock samples from the northern sector of the Rio Grande do Sul Coastal Plain in southern Brazil revealed a diverse and well-preserved ostracod assemblage. In addition to ostracods, other microfossils such as foraminifers, echinoderm spines, and fish remains were also found. The taxonomic composition of the ostracods suggests that the beachrocks represent environmentally condensed assemblages. This preliminary study highlights the importance and potential of micropaleontology in understanding the processes involved in beachrock formation.