Late Pleistocene changes in terrestrial biomarkers in sediments from the central Arctic Ocean

Abstract

Biomarkers in Late Pleistocene sediments collected from the Integrated Ocean DrillingProgram (IODP)-Arctic Coring Expedition (ACEX) Hole M0004C (central Arctic Ocean) were investigated. The major biomarkers are long-chain n-alkanes, n-fatty acids and n-alkan-1-ols, indicating fresh organic matter (OM) derived predominantly from higher plants. The dominance of terrestrial biomarkers is attributed to severe OM degradation caused by slow sedimentation in oxygen-rich benthic water and/or low primary production due to permanent sea-ice coverage. Hopanes, representing thermally altered OM, tend to be abundant in samples with abundant ice rafted debris (IRD). An OM-rich dark grey layer deposited during marine isotope stage (MIS) 6 contains a significant amount of branched glycerol dialkyl glycerol tetraethers (branched GDGTs), suggesting ice erosion of organic-rich continental soil followed by transportation to the central Arctic by drifting ice. The labile-refractory index (i.e., the abundance ratio of long-chain n-alkan-1-ols to the sum of long-chain n-alkanes and long-chain n-alkan-1-ols) decreases above the dark grey layer, indicating that the OM became more refractory. This change suggests that coverage of the source region by OM-rich soil decreased because of extensive glacial erosion during MIS-6.

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;.…”

Changes in terrestrial organic matter input to the Mendeleev Ridge, western Arctic Ocean, during the Late Quaternary

“…1) are long-chain n-alkanes, n-fatty acids and n-alkan-1-ols, indicating terrestrial OM input. The dominance of terrestrial biomarkers was attributed to severe OM degradation caused by slow sedimentation in oxygen-rich benthic water and/or low primary production due to permanent sea ice coverage (Yamamoto et al, 2008). The dominance of long-chain n-alkanes and high BIT in Core HLY0503-08JPC is consistent with these earlier observations in the central Arctic Ocean, suggesting that the environment of the study site has been under similar conditions.…”

“…4H). The range of values is similar to that in the central Arctic Ocean (~0.5-1; Yamamoto et al, 2008), but is anomalously high for normal pelagic marine sediments. The high BIT index in the western Arctic Ocean reflects a significant contribution of terrestrial soil OM.…”

“…The high BIT index in the western Arctic Ocean reflects a significant contribution of terrestrial soil OM. Yamamoto et al (2008) reported that major biomarkers in central Arctic sediments (Site M4, Fig. 1) are long-chain n-alkanes, n-fatty acids and n-alkan-1-ols, indicating terrestrial OM input.…”

“…Organic geochemistry has also been applied in such studies; the amount and quality of bulk OM have been reported for sediment cores from the Amundsen Basin (Schubert and Stein, 1996) and the Siberian continental margins (Stein et al, 2001(Stein et al, , 2004Bouscein et al, 2002). Biomarkers are also used as source-specific tracers in oceanographic studies in the central Arctic Ocean (Schubert and Stein, 1997;Belicka et al, 2002;Yunker et al, 2005), the northern Eurasian margin (Peulvé et al, 1996;Fahl and Stein, 1997;Zegouagh et al, 1996) and North American margins (Yunker et al, 1995;Belicka et al, 2004), and in paleoceanographic studies in Holocene and late Pleistocene sequences of the Laptev and Kara Seas (Fahl and Stein, 1999;Stein et al, 2001), and the Lomonosov Ridge in the central Arctic (Yamamoto et al, 2008).…”