Carbonate granulates from the continental shelf of the State of Paraíba, NE Brazil

The Brazilian continental shelf, particularly its northeast sector, is a conducive environment for the deposition of biogenic carbonate granules. In Brazil, the use of marine calcium carbonate (CaCO 3 ) derived from biogenic sediments is still in its early stages but its economic potential has become significant. Regarding the State of Paraíba, located in northeastern Brazil, it has been acknowledged that the survey and study of the sediments deposited on its continental shelf is not only of economic importance, but will lead to the understanding of their distribution and of the influence of geological, hydrodynamic, and biological processes in their deposition. For this purpose, 1096 sediment samples, collected during the GranMar project (Marine Granules of Brazil), were analyzed in this study. Sampling was conducted using a Van Veen-type grab sampler, and sampling depth was determined using an EDO 185 Oceanographic 12 kHz echosounder. The grain-size analyzes were conducted by sieving and CaCO 3 content determinations were performed using an adapted Bernard calcimeter. The bathymetric map revealed morphological evidence of distinct seafloor characteristics between the northern and southern regions of the shelf. The shelf is defined as carbonate-rich, with CaCO 3 contents above 75 wt.%, consisting mainly of bioclasts. The most abundant particle-size fractions range from gravel to sand. Three sedimentary facies were mapped along the continental shelf of the State of Paraíba: Bioclastic Sand with Granules and Gravel; Bioclastic Gravel and Bioclastic Sand. The facies characterization of continental shelf sediments, is important not only for a better understanding the shelf environment, reflecting past and current geological and hydrodynamic processes, but also for conservation, management, and assessment of environmental impacts, as preconized by the United Nations Sustainable Development Goal 14–Life Below Water.