Organic matter analyses (Rock-Eval 6 and LECO) of samples collected in cores and sediment traps of the Mozambique Channel during the PAMELA project

The purpose of this publication is to give access to the analytic data set which has been used in a paper submitted to the journal Marine Geology (Torelli et al., submitted). This paper proposes a general study of the organic matter (OM) distribution within the recent Quaternary sediments of the Mozambique Channel (southern part of the east African margins). The study was conducted in the framework of the PAMELA (PAssive Margin Exploration LAboratory) research project (Bourillet et al., 2013). This study is mainly based on Rock-Eval 6 (RE6) analyses of samples collected during several marine surveys: Pamela-Moz01 (Olu, 2014), Pamela-Moz04 (Jouet and Deville, 2015) and Pamela-Moz08 (Khripounoff, 2016; Fig. 1). 394 RE6 analyses were performed on samples collected with the Küllenberg corer (recovered core length up to 12 m) of the R/V Atalante (Pamela-Moz01 survey) and the Calypso corer (recovered core length up to 33 m) of the R/V Pourquoi Pas? (Pamela-Moz04 survey), 11 RE6 analyses on samples collected with an interface multicorer (30-40 cm maximum penetration), and 101 RE6 analyses on samples collected with sediment traps in moorings located 47 m above seabed. We provide here the whole RE6 analyses (Table 1) and the correlation made between RE6 analyses and LECO elemental analyses concerning the total carbon (Tables 2 and 3). The analysis of samples collected with particle traps within the deep-water areas of the Mozambique Basin has shown that the OM is transported by turbidite and/or contour currents and deposited while preserving Total Organic Carbon (TOC) contents between 1.5 and 3%Wt. However, the sedimentary OM is largely oxidized (Oxygen Index > 300 mg CO2/g TOC) and only a small amount of TOC (< 0.5%Wt) is preserved within the recent sediments of the distal area of the Zambezi turbidite system at water depths below 2500 m. Interface sediments sampled to a maximum depth of 40 cm, have shown intermediate TOC values between those collected in the particle traps and those from piston cores suggesting that the degradation of the OM is mainly active at the water-sediment interface. This OM oxidation and degradation process in the deep-water domains of the Mozambique Basin is probably due to the conjugate effects of low sediment accumulation rate and high permeability of the coarse-grained sediments but also to important bottom currents that promote the remobilization and the rearrangement of fine grained sediments.   References   Bourillet, J.F., Ferry, J.N., Bourges, P., 2013. PAMELA, Passive Margins Exploration Laboratories. https://dx.doi.org/10.18142/236. Jouet, G., Deville, E., 2015. PAMELA-MOZ04 cruise, R/V Pourquoi Pas? https://doi.org/10.17600/15000700. Khripounoff, A., 2017. PAMELA-MOZ08 cruise, R/V Antea. https://doi.org/10.17600/17003900. Olu, K, 2014. PAMELA-MOZ01 cruise, R/V L'Atalante, https://dx.doi.org/10.17600/14001000. Torelli, M., Battani, A., Pillot, D., Kohler, E., Lopes De Azevedo, J., Kowalewski, I., Pastor, L., Brandily, C., Schmidt, S., Jouet, G., Deville, E. (Submitted to Marine Geology). Organic matter distribution in modern sediments of the Mozambique Channel: Evidence for widespread oxidation processes in the deep-water domains.
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