Biogenic and detrital-rich intervals in central Arctic Ocean cores identified using x-ray fluorescence scanning

Abstract

X-ray fluorescence (XRF) scanning of sediment cores from the Lomonosov Ridge and the Morris Jesup Rise reveals a distinct pattern of Ca intensity peaks through Marine Isotope Stages (MIS) 1 to 7. Downcore of MIS 7, the Ca signal is more irregular and near the detection limit. Virtually all major peaks in Ca coincide with a high abundance of calcareous microfossils; this is particularly conspicuous in the cores from the central Arctic Ocean. However, the recorded Ca signal is generally caused by a combination of biogenic and detrital carbonate, and in areas influenced by input from the Canadian Arctic, detrital carbonates may effectively mask the foraminiferal carbonates. Despite this, there is a strong correlation between XRF-detected Ca content and foraminiferal abundance. We propose that in the Arctic Ocean north of Greenland a common palaeoceanographic mechanism is controlling Ca-rich ice-rafted debris (IRD) and foraminiferal abundance. Previous studies have shown that glacial periods are characterized by foraminfer-barren sediments. This implies that the Ca-rich IRD intervals with abundant foraminifera were most likely deposited during interglacial periods when glaciers left in the Canadian Arctic Archipelago were still active and delivered a large amount of icebergs. At the same time, conditions were favourable for planktic foraminifera, resulting in a strong covariance between these proxies. Therefore, we suggest that the XRF scanner's capability to efficiently map Ca concentrations in sediment cores makes it possible to systematically examine large numbers of cores from different regions to investigate the palaeoceanographic reasons for the calcareous microfossils’ spatial and temporal variability

Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

“…When identified, the pink-white (PW) sediment layers PW 1 (MIS 8 to 7) and PW 2 (early MIS 5) representing ice-rafting events of North American Paleozoic dolomite were used to check for a reasonable alignment between cores (tie points from Table 3 of Cronin et al, 2014). The B. aculeata and T. egelida foraminiferal zones are particularly important because they are traceable across most of the central Arctic Ocean (Hanslik et al, 2013;Cronin et al, 2014). These tie points allow correlation of sediments deposited from MIS 13 to MIS 1 (about the last 550 ka) so that individual records of microfaunal density can be aligned and stacked.…”

“…Dissolution must be considered a potential factor affecting the abundance and preservation of calcite microfossil shells in the Arctic Ocean, especially in parts of the Eurasian Basin in the eastern Arctic and in pre-MIS 11 sediments Hanslik et al, 2013). Studies of deglacial, Holocene and/or modern Arctic benthic foraminiferal faunas have been important in attributing dissolution to explain observed species distributions.…”

“…Although the effects of GICs on the sedimentary record are complex, GICs are evident in manganese concentrations (Jakobsson et al, 2000;L€ owemark et al, 2014;Stein et al, 2015), color, grain size and bulk density , mineral and trace element content (Fagel et al, 2014), neodymium (Haley et al, 2008), organic geochemistry (Yamamoto and Polyak, 2009;Schubert and Stein, 1996;Stein et al, 2001), foraminiferal d 18 O Spielhagen et al, 2004;Knies et al, 2007;Adler et al, 2009) and calcareous microfossils (Herman, 1970;Poore et al, 1994;Polyak et al, 2009;Hanslik et al, 2013).…”

Biological response to climate change in the Arctic Ocean: the view from the past

“…The density of calcareous microfossils in sediments from central Arctic ridges is directly linked to interglacial and glacial climate regimes and changes in sea-ice cover, surface productivity, sedimentation, and post-depositional processes [12,119]. It is well established that foraminifera (benthic and planktic) and ostracodes are major components of the sand-sized fraction in interglacial sediments in contrast to near absence in glacial-age sediments [1,80] (Fig. 3d).…”

Optimization of Itrax Core Scanner Measurement Conditions for Sediments from Submarine Mud Volcanoes

“…Numerous scientific studies in recent years have shown their value in different areas of the earth sciences like palaeoceanography (Peterson et al 2000;Hodell et al 2008;McHugh et al 2008;Rebolledo et al 2008;Hibbert et al 2010;Hanslik et al 2013), palaeoclimatology (Donnelly and Woodruff 2007;Löwemark et al 2008;Metcalfe et al 2010;Vasskog et al 2011;Aarnes et al 2012), dendrochronology (Helama et al 2008(Helama et al , 2010, mining ) and forensic sciences (Smith et al 2008). Currently they are widely used for facies characterisation in both marine and lacustrine sediments and subsequent interpretation of the geological evolution of oceans and lakes (Teodoru et al 2007;Coolen et al 2009;Kylander et al 2011;Giguet-Covex et al 2012).…”