The data refer to the geochemical and isotopic characterization of microbial carbonate in the shallow platform of the South Atlantic Ocean, Espírito Santo - Brazil. Carbon and oxygen isotope analysis fractions (δ¹³C and δ¹⁸O) were measured on six carbonate laminate samples using isotope ratio mass spectrometry (IRMS) on a Thermo Fisher Scientific Delta V Advantage instrument. Approximately 0,4-0,6 mg of carbonate was reacted with 100% phosphoric acid at 72ºC to release CO2 gas. International standards (NBS18, NBS19, IAEA-CO-1, IAEA-CO-8, IAEA-CO-9, and IAEA-603) were used for calibration. The analytical precision for δ13C and δ18O was better than 0,01% and 0,25%, respectively. Isotopic values are reported in delta notation (‰) relative to the Vienna Pee Dee Belemnite (VPDB) standard.

The study was carried out between 2021 and 2023 on the beach of Castelhanos in a carbonate bank to analyze the depositional dynamics throughout the Holocene. The occurrence of microbial carbonates in the open marine environment is uncommon globally, configuring an excellent proxy for the reconstitution of relative variations in sea level and paleoclimate.