Reservoir Ages in the Western Tropical North Atlantic from One Coral off Martinique Island (Lesser Antilles)

Abstract

Sea surface reservoir ages (R) are reported from radiocarbon (14C) measurements of the annual growth bands of coral Siderastrea siderea collected on the Atlantic coast off Martinique Island, in the Lesser Antilles volcanic arc. Mean values of R are similar between 1835 and 1845 during pre-anthropogenic times at 385±30 yr and between 1895 and 1905 at 382±20 yr when there was a huge eruption from the Montagne Pelée volcano in 1902–1903. Limited 14C aging of sea surface (~40 yr) may be due to enhanced volcanic activity. Variability of R is slightly greater during 1835–1845 than during 1895–1905. It is linked to a moderate increase of ∆14C of 5‰, strengthened by a clear increase of δ18O of 0.4‰. This is attributed to a decrease of the northward advection of the South Atlantic Waters into the western tropical North Atlantic and Caribbean Sea and relative enhanced westward flux of the tropical North Atlantic surface waters, the southern waters having lower values of 14C and δ18O than the North Atlantic ones. From 1835 to 1845, the fraction of the South Atlantic Waters transported up to Martinique Island was reduced from 25% to 15%.

Sedimentary Records in the Lesser Antilles Fore‐Arc Basins Provide Evidence of Large Late Quaternary Megathrust Earthquakes

“… Age model established for event deposits free core (hemipelagic section depleted from event deposits) with Oxcal 4.4 program (Bronk Ramsey, 2009) by using the Marine 20 calibration curve (Heaton et al., 2020), the recalculated reservoir age Δ R value recalculated from Paterne et al. (2018) and a k parameter of 1. Modeled radiocarbon ages are indicated in red and the turbidite age distributions are in black, both with the mean and standard deviation, Dark gray interpolated interval: 1‐sigma probability (68.3%), light gray interpolated interval: 2‐sigma (95.4%).…”

“…The radiocarbon ages were calibrated with the OxCal 4.4 software (Bronk Ramsey, 2009) using the IntCal Marine20 calibration curve (Heaton et al., 2020), and the regional offset Δ R value of −156 ± 32 years, recalculated from Paterne et al. (2018) for the MARINE20 curve (with CALIB REV8.2 software, Stuiver et al., 2021). Then, we used a Bayesian model with a P‐sequence deposition model in OxCal (Poisson distribution, Bronk Ramsey, 2008; Bronk Ramsey & Lee, 2013) to construct an age‐depth model of event‐free sediment sections, which we built for each core by removing all instantaneous event deposits.…”

“…The chronology of event deposits in all cores was obtained using AMS 14 C dating on at least 10 mg of planktonic foraminifera picked from the >150 μm sediment fraction a few centimeters below or above turbidites (Table 2) at LMC14 (ARTEMIS CNRS facility, France) or the BETA ANALYTICS Laboratory (USA). The radiocarbon ages were calibrated with the OxCal 4.4 software (Bronk Ramsey, 2009) using the IntCal Marine20 calibration curve (Heaton et al, 2020), and the regional offset ΔR value of −156 ± 32 years, recalculated from Paterne et al (2018) for the MARINE20 curve (with CALIB REV8.2 software, Stuiver et al, 2021) Bronk Ramsey & Lee, 2013) to construct an age-depth model of event-free sediment sections, which we built for each core by removing all instantaneous event deposits. The regularity of the sedimentation rate into the model is determined by the k factor, which we chose to be equal to 1 (Bronk Ramsey, 2008;Bronk Ramsey & Lee, 2013).…”

“…The ages are calibrated with OxCal software (Bronk Ramsey, 2009) using the MARINE 20 curve (Heaton et al., 2020) and the delta R recalculated from Paterne et al. (2018). The cal BP ages are indicated by their mean ± standard deviation.…”

“…By converting the SBP vertical scale from two-way travel time to depth using the mean P-wave velocity measurements obtained on the cores (1,700 m/s for core CAS16-01PC, 1,300 m/s for core CAS16-07PC, and 1,500 m/s Note. The ages are calibrated with OxCal software (Bronk Ramsey, 2009) using the MARINE 20 curve (Heaton et al, 2020) and the delta R recalculated from Paterne et al (2018). The cal BP ages are indicated by their mean ± standard deviation.…”