“…Other limestone occurrences, similar to those reported in the PE quarry, including reefal, peri-reefal deposits and calciturbidites, have been described along the western boundary of OMZ (Machado et al, 2020b;Oliveira et al, 2019). These limestones date from the patulus (uppermost Emsian, Lower Devonian) to hemiansatus (lowermost Givetian, Middle Devonian) conodont zones Machado et al, 2009Machado et al, , 2020aOliveira et al, 2019) and suggest an alignment of atoll-like reef structures developed along the southern border of the OMZ, during the Emsian to Givetian (Machado et al, 2020b;Moreira et al, 2021;Oliveira et al, 2019). Within the Cabrela Basin, limestones containing conodonts attributed to the lower gigas zone (currently lower rhenana) (upper Frasnian, Upper Devonian;Boogaard, 1983) have also been reported.…”