Radiocarbon Calibrated ages of surface marine sediments at the Southeast Pacific (methods/regional reservoir ages/results)

The radiocarbon ages (14C) obtained from surface sediment samples at the South East Pacific were measured in mixed upper thermocline planktonic foraminifera (MUTPF), Mixed shallow infaunal benthic foraminifera (MBF) and monospecific benthic foraminifera. All the foraminifera selected for the analysis were Benga-Rose unstained foraminifera. This data set (raw data, radiocarbon ages, 14C) is storage by PANGAEA Data Publisher for Earth & Environmental Science.  Radiocarbon ages of surface marine sediments at the South East Pacific (14CSS_SEP_version1). 

To obtain sediment surface calendar ages, planktic and benthic foraminifera radiocarbon ages were corrected by different regional marine surface reservoir ages expressed as R (R = 14C from the ocean - 14C from the atmosphere), which represents the deviation from the SHCal20 curve at a given time. These R values account for four different upwelling regimes in the South East Pacific: i) a northern upwelling regime between Lima, Peru and Coquimbo, Chile (~11-30 ºS), characterized by permanent upwelling, with an estimated modern R of 505 ± 135 years; ii) a central upwelling zone between Coquimbo and Curicó, Chile (~30-35 °S) were upwelling is permanent but weaker in austral winter, with an estimated modern R of 460 ± 100 years; iii) a southern upwelling regime between Curicó and Valdivia, Chile (~35-40 ºS), where upwelling is seasonal but relatively high, with an estimated modern R of 510 ± 25 years; iv) and finally a north Patagonian zone (>40 ºS) in which no upwelling occurs, with an estimated modern R of 450 ± 55 years. The R values for each of these zones were calculated as the mean modern R estimated based on Merino et al. (2018). Samples with 14C age older than 1000 yrs BP were corrected by an R estimation by Zhao and Keigwin (2018) or Fontugne et al. (2004)  in the northern upwelling zone,  by  Merino et al. (2018) in the central and southern upwelling zone, and by Siani et al. (2013) in the north Patagonia upwelling zone. For PG4-18 (142 m, dated by mixed benthic foraminifera) due the not availability of published R estimations in these latitudes and water depth, a R equal to the modern estimated by Merino et al. (2018) was applied. For the deep benthic foraminifera, an additional correction was made to account for the benthic-planktic foraminifera 14C age difference, which was estimated at 500 ± 250 years. The correction was estimated as the mean benthic-planktic 14C age in core 22SL retrieved nearby site PG4-23 (De Pol-Holz et al., 2010). The planktonic and benthic foraminifera radiocarbon ages were then calibrated by the SHCal20 curve (Hogg et al., 2020) using the python library iosacal 0.6.0 (Costa et al., 2022, https://pypi.org/project/iosacal/). All calibrated ages are reported as years Before Present (BP, considering present the year 1950). We considered foraminifera with radiocarbon ages >1950 (Post-radiocarbon boom period) or samples with radiocarbon ages smaller than the average of the different regional modern reservoir ages calculated for the SEP as recent. 

In this ZENODO chanel you will find 

1) R values (regional and mobile by time) for the South East Pacific 

2) Radiocarbon calibrated ages data for 14CSS_SEP_version1 (using Merino et al., 2018 original R calculations based in Marine13 radiocarbon age calibration curve) 

3) Radiocarbon calibrated ages data for 14CSS_SEP_version1 (using Merino et al., 2018 recalculated R based in SHCal20 radiocarbon age calibration curve) 

3) Python Code developed for calculate calibrated radiocarbon ages based in regional and mobile R https://github.com/Paleobiogeochemistry/calibrar14ages_surfacesediments