Do drifts deposited adjacent to carbonate platforms record the signal of global carbon isotopic values?

Abstract

This study investigates the d 13 C values of Middle Miocene-Modern drift deposits and periplatform sediments in the Maldives and compares these data with the global d 13 C values derived from bulk oceanic sediments and foraminifera. This comparison reveals that while the d 13 C values of the early Miocene periplatform sediments in the Maldives appear to track the global record of d 13 C values, including increases associated with the Oligocene-Miocene boundary as well as the variations within the Monterey Event, the correlation with the Monterey Event may be coincidental. It is suggested that variations in d 13 C values do not reflect changes in oceanic dissolved inorganic carbon, but instead pulses of sediment arising from platform progradation that contribute carbonates with elevated d 13 C values derived from the adjacent shallow-water atolls. This conclusion is supported both by correlations between the seismic sequence architecture and the d 13 C values which document progradation of 13 C-rich platform sediments, and also by the continuation of the interval of 13 C-rich sediments past the end of the Monterey Event at 13 Ma within the drift.

Seawater-buffered diagenesis, destruction of carbon isotope excursions, and the composition of DIC in Neoproterozoic oceans

“…We suggest that the fringing turbidites are composed of carbonate that was shed off the platform with its sedimentary δ 13 C intact (e.g., ref. 50). We infer that they accumulated beyond the zone of seawaterbuffered diagenesis (Fig.…”

Changes in mesophotic carbonate‐platform export across the end of the last glacial cycle (Saya de Malha Bank, western Indian Ocean)

“…These periplatform deposits consist of pelagic material from the water column and neritic material from the shallow-water areas on top of the platform. The supply of neritic carbonate has a unique fingerprint, as it is rich in high strontium aragonite (HSA) and high magnesium calcite (HMC), and carries a unique carbon isotope signal (Bialik, Reolid, et al, 2020;Schlager et al, 1994;Swart et al, 2019). These features in turn can be reflected in the observed patterns in the rock record as variations in exported HSA and HMC may impact the lithified product through differential diagenesis (Nohl et al, 2018(Nohl et al, , 2021.…”

Changes in mesophotic carbonate-platform export across the end of the last glacial cycle (Saya de Malha Bank, western Indian Ocean)

“…These periplatform deposits consist of pelagic material from the water column and neritic material from the shallow-water areas on top of the platform. The supply of neritic carbonate has a unique fingerprint, as it is rich in high strontium aragonite (HSA) and high magnesium calcite (HMC), and carries a unique carbon isotope signal (Bialik et al, 2020b;Schlager et al, 1994;Swart et al, 2019). These features in turn can be reflected in the observed patterns in the rock record as variations in exported HSA and HMC may impact the lithified product through differential diagenesis (Nohl et al, 2021(Nohl et al, , 2018.…”