Geochemistry of organic matter of bottom sediments in the rises of the central Arctic Ocean

Abstract

Based on geomorphological, lithological, and facial characteristics of the East Arctic continental margin, we studied the main factors controlling the Late Cenozoic supply of organic matter (OM) to the bottom sediments of the Central Arctic rises of the Arctic Ocean. Complex analysis of dispersed OM in the samples taken during the expeditions of the R/V “Akademik Fedorov” in 2000 and 2005 showed a significant difference between the sediments of the Lomonosov Ridge and Mendeleev Rise. The bottom sediments of the latter are strongly transformed and lack terrigenous components, as evidenced results from the main geochemical characteristics (contents of Corg, Ccarb, Norg, bitumens, and humic acids) and the composition and distribution of hydrocarbon molecular markers (alkanes, saturated and aromatic cyclanes). The obtained data evidence that ancient sedimentary rocks containing genetically uniform deeply transformed (up to mesocatagenesis) OM played a significant role in the formation of the Pleistocene–Holocene sediments of the axial part of the Mendeleev Rise.

Petroleum-related hydrocarbons in deep and subsurface sediments from South-Western Barents Sea

“…The slight differences observed between these samples are in accordance with existing knowledge on diagenetic transformation of bottom sediment OM in continental shelf and deeper sediments (Degens and Mopper, 1976;Yunker et al, 1995;Fahl and Stein, 1999;Yamamoto et al, 2008;Petrova et al;.…”

“…This may be indicative of an abrupt change in sedimentation conditions during a marine transgression and/or abrupt increase in primary bioproductivity in the marine environment since these compounds are markers of lipids of biotic origin (Venkatesan and Kaplan, 1987;Grimalt and Allbaiger, 1987;Petrova et al, 2010). However, this possibility does not seem plausible in view of the lithological homogeneity of the sediment core and of the increase of anomalies when the data are normalised to TOC.…”

Characterization of Organic Matter of the Laptev Sea Eroded Coastal Sediments: A Case Study from the Cape Muostakh, Bykovsky Peninsula

“…Conversely, OEP index increase over the cliff section, while Eh decrease (Figure 8c). The Σ(C17-C19)/Σ(C27-C31) ratio and C/D index, which characterize the relative content of low molecular weight n-alkanes that are markers of hydrobionts and bacterial activity [46,47], have low values compared with those for the bottom sediments of the Laptev Sea and other areas of the Eastern Arctic [45,46,48,49], and reach maximums in samples "11" and "21.5" (Table 2). Alongside, there is a positive correlation between these coefficients and the Ki index, which may indicate some contribution of marine OM (sample "5", "11") or intense bacterial activity in sediments (sample "21.5").…”

“…1 It means that analytically significant signal of the component is missing. 2 A/B is the ratio of the sum of the peak areas of n-alkanes over the even envelope of the molecular mass distribution (C14, C15, C16, C17, C18, C19, C20, C21, C22, C24, C26, C28, C30, C32, C34) to the sum of the peak areas of high-molecular n-alkanes (the markers of the terrestrial vegetation -C23, C25, C27, C29, C31, C33, C35) by m/z 57 (see [46], and Figure S6). 3 C/D is the ratio of the sum of the peak areas of low molecular weight n-alkanes (C14, C15, C16, C17, C18) to the sum of the peak areas of high molecular weight n-alkanes (C19, C20, C21, C22, C24, C26, C28, C30, C32, C34) over the even envelope of the molecular mass distribution by m/z 57 (see [48], and Figure S6).…”

Molecular Indicators of Sources and Biodegradation of Organic Matter in Sediments of Fluid Discharge Zones of Lake Baikal

“…Hydrocarbon molecular markers (MM or biomarkers) are components of the dispersed organic matter (OM) and chemical fossils that inherit the chemical structure of their biological precursors and, thus, are a universal link in the chain of the sequential transformation of OM: biopolymers-biomonomers-geomonomers-geopolymers [20][21][22][23]. Their usage allows for the determination of the OM origin including the input from biogenic and abiogenic sources, the level of OM transformation during thermal maturation and biodegradation as well as the influence of endogenous and exogenous processes.…”