Chitinozoans of the Pitinga Formation (Trombetas Group, Amazonas Basin, Northern Brazil): preliminary results

摘要

In nine boreholes and three outcrops, the Pitinga Formation consisting of a basal shale with siltstone and minor sandstone interbeds was studied using palynological and biostratigraphical methods. The fossiliferous deposits of the Pitinga Formation outcrops have an indicative fauna from Late Llandoverian to Early Wenlockian yielding Pogonochitina djalmai, Cyathochitina caputoi, Margachitina margaritana, Desmochitina densa and Conochitina acuminata. The borehole samples show assemblages with Ancyrochitina primitiva, A. aff. A. tomentosa, Angochitina ?thadeui, Cingulochitina aff. C. ervensis, Cyathochitina caputoi, Margachitina margaritana, Margachitina aff. M. saretensis, Pogonochitina inornata, Tanuchitina aff. T cylindrica, T elenitae, Ramochitina illiziensis and Vinnalochitina corinnae. The age of the formation is Early Wenlockian to Middle-Late Llandoverian and Pridolian to Ludlovian for the Lower and Upper Pitinga Formation respectively.