This dataset presents radiocarbon and geochemical records from sediment core CF10-09A, collected in the Cabo Frio upwelling system on the southeastern Brazilian continental margin (23.20°S, 41.74°W; 117 m water depth). The data were generated to evaluate radiocarbon age offsets between organic carbon (OC) and carbonate fractions and to support Holocene paleoceanographic reconstructions in a dynamic coastal upwelling environment.Radiocarbon measurements of planktonic foraminifera (Globigerinoides ruber) were obtained using a MICADAS accelerator mass spectrometry system at the Alfred Wegener Institute. The dataset includes conventional radiocarbon ages for both the carbonate and OC fractions, based on the radiocarbon measurements described in Ceccopieri et al. (2016) and Lessa et al. (2016), respectively, as well as the calculated offset between carbonate and OC conventional ages. Conventional ages were extrapolated along the entire core using the tune function of the Astrochron package in R.The revised age model, based on the carbonate fraction, was developed using the Marine20 calibration curve (Heaton et al., 2020) and a regional marine reservoir correction of 67 ± 33 years (Macario et al., 2016). Additional downcore parameters include total organic carbon (TOC), stable carbon isotopic composition of bulk organic matter (δ¹³C), total alkenone, crenarchaeol, and branched GDGT contents, branched and isoprenoid tetraether (BIT) index values, and estimates of terrestrial and marine organic carbon contributions. The dataset spans approximately the last 5.8 thousand calibrated years.

a: 14C carbonate ages were calibrated with Marine20 (Heaton et al., 2020) curve using the Bacon package in R (Blaauw and Christen, 2011). The local marine reservoir correction (ΔR) considered was 67 ± 33 years (Macario et al., 2016).b: Conventional 14C carbonate and organic matter (OM) ages were interpolated using the tune function of the Astrochron package in R, with the carbonate age–depth model as a stratigraphic guide. Conventional OM ages were obtained from Lessa et al. (2016).c: Branched Isoprenoid index (BIT) calculated according to Hopmans et al. (2004).d: Terrestrial (fterrestrial) and marine (fmarine) contribution was calculated based on a two end-member mixing model using the stable carbon isotopic ratio (δ13C) and calculated based on a two-member mixing model using δ13C values.