Arctic Ocean manganese contents and sediment colour cycles

Abstract

Cyclical variations in colour and manganese content in sediments from the central Arctic Ocean have been interpreted to represent climatically controlled changes in the input of Mn from the Siberian hinterland, and/or variations in the intermediate and deep water ventilation of the Arctic basins, although a diagenetic origin has not been excluded. A reinvestigation of core 96/12‐1pc using an Itrax X‐ray fluoresence (XRF) core scanner confirms that these colour cycles are indeed controlled by variations in Mn content, although changes in the source region of the sediment may override the Mn colour signal in certain intervals. The prominent Mn cycles show no correspondence to any of the other measured elements. This decoupling of Mn and the bulk chemistry of the sediment is taken to indicate that the cycles observed are caused by variations in water column ventilation and riverine input, rather than variations in sediment source or diagenesis. We therefore conclude that the Mn maxima do represent warm phases with increased ventilation and/or riverine input, and that they therefore could be used for chronostratigraphic correlation between cores from the central Arctic Ocean, where traditional isotope stratigraphy is difficult or impossible to establish because of the lack of calcareous microfossils.

Twenty Years of XRF Core Scanning Marine Sediments: What Do Geochemical Proxies Tell Us?

“…Covariance with other redox-sensitive or detrital elements may indicate potential Mn sources. Pervasive Mn enrichment occurs in central Arctic Ocean sediments during interglacials and interstadials (Löwemark et al 2008;O'Regan et al 2010). This is attributed to enhanced Mn flux to central Arctic during deglacial or interglacial periods, or from sluggish intermediate and deep-water circulation during glacials (Jakobsson et al 2000).…”

Late quaternary ice-rafted detritus events in the Chukchi Basin, western Arctic Ocean

“…On the other hand, the reduced biological productivity and low sedimentation rate under sea ice cover bring definite difficulties in applications of biostratigraphy and foraminiferal oxygen and carbon isotope stratigraphy [11]. Multi-proxy approaches are applied to establish the stratigraphy of deep sea sediments in the Arctic Ocean, such as, AMS 14 C dating [12], sediment color cycles [13,14], foraminiferal abundance and IRD content [4,[6][7][8]15], magnetic susceptibility and color reflectance [16]. For those sediments exceeding the 14 C dating, magnetostratigraphy [17], 10 Be [2] and optically stimulated luminescence (OSL) dating [18] are also used to establish their stratigraphic framework.…”

“…Brownish-yellowish and grayish cycles of sediment color change in the Arctic Ocean are considered to represent interglacial and glacial cycles [13,14]. The brownish-yellowish sediments reflect abundant biomass and display interglacial environment of high productivity, which indicate the prominent influences of the enhancing Atlantic Water and bottom water with strong oxidability, whereas the grayish sediments mirror the strong reduction of biomass in the glacial environment with extended ice cover, together with the weakened influences of the Atlantic Water and bottom water [8,11].…”

“…Consequently, the integrated core stratigraphy of core M03 can be established, based upon the combination of sediment lithology and color cycles, AMS 14 …”

Deep-sea trace fossil and benthic foraminiferal assemblages across glacial Terminations 1, 2 and 4 at the “Shackleton Site” (IODP Expedition 339, Site U1385)

“…However, studies on the relationship between glacial/interglacial cycles, the involved environmental changes, and ichnological data are scarce, and mainly focusing on the differentiation between bioturbated and unbioturbated, laminated intervals (e.g., Villa et al, 2003) or variations in the Bioturbation Index (Chondrogianni et al, 2004). Only occasionally the ichnotaxonomical composition of trace fossil assemblages has been presented (e.g., Phillips and Grantz, 1997;Löwemark et al, 2006Löwemark et al, , 2008Löwemark et al, , 2012. Benthic foraminifera are classic micropaleontological proxies for past changes in deep water hydrography (see Jorissen et al, 2007 for a review), and they have been used for the reconstruction of bottom water conditions along the western Iberian Margin since the last glacial maximum (Caralp, 1987;Baas et al, 1998;Schönfeld and Zahn, 2000;Schönfeld et al, 2003).…”