Aeolian sediment transport and deposition in a modern high‐latitude glacial marine environment

Abstract

Associate Editor -Nick LancasterABSTRACT Aeolian sand and dust in polar regions are transported offshore over sea ice and released to the ocean during summer melt. This process has long been considered an important contributor to polar sea floor sedimentation and as a source of bioavailable iron that triggers vast phytoplankton blooms. Reported here are aeolian sediment dispersal patterns and accumulation rates varying between 0Á2 g m À2 yr À1 and 55 g m À2 yr À1 over 3000 km 2 of sea ice in McMurdo Sound, south-west Ross Sea, adjacent to the largest ice free area in Antarctica. Sediment distribution and the abundance of southern McMurdo Volcanic Group-derived glass, show that most sediment originates from the McMurdo Ice Shelf and nearby coastal outcrops. Almost no sediment is derived from the extensive ice free areas of the McMurdo Dry Valleys due to winnowed surficial layers shielding sand-sized and silt-sized material from wind erosion and because of the imposing topographic barrier of the north-south aligned piedmont glaciers. Southerly winds of intermediate strength (ca 20 m sec À1 ) are primarily responsible for transporting sediment northwards and offshore. The results presented here indicate that sand-sized sediment does not travel more than ca 5 km offshore, but veryfine sand and silt grains can travel >100 km from source. For sites >10 km from the coast, the mass accumulation rate is relatively uniform (1Á14 AE 0Á57 g m À2 yr À1 ), three orders of magnitude above estimated global atmospheric dust values for the region. This uniformity represents a sea floor sedimentation rate of only 0Á2 cm kyr À1 , well below the rates of >9 cm kyr À1 reported for biogenic-dominated sedimentation measured over much of the Ross Sea. These results show that, even for this region of high-windblown sediment flux, aeolian processes are only a minor contributor to sea floor sedimentation, excepting areas proximal to coastal sources.

Sediments Beneath Multi-Year Sea Ice: Delivery By Deltaic and Eolian Processes

“…Winds capable of transporting very fine sand and silt for . 100 km are not uncommon in this area (e.g., Chewings et al 2014). Supporting evidence for this processes comes from the grain size of sediment entrained in snow collected in 2010 from the sea ice , 15 km offshore of the Explorers Cove coast.…”

“…Integrating these data on velocity required for transport with recorded wind speeds suggests that eolian transport of sediment onto sea ice at Explorers Cove is not common, but is a significant process. Although sand is the dominant grain size in the Taylor Valley (e.g., Gillies et al 2013), grains , 70 mm in diameter may be carried in suspension for tens to hundreds of kilometers (Atkins and Dunbar 2009;Chewings et al 2014).…”

“…2), seafloor grab samples (, 0.3 km offshore), and sea-ice transect (Table 3) in this study. Published grain size analyses of sediment from more distal seafloor (n 5 7) and sea-ice samples (n 510) are from Dunbar and Barrett (2004). rates calculated from sediment in yearly snow on sea ice during 2007(Atkins and Dunbar 2009Chewings et al 2014).…”

Glacial-Marine Sedimentation

“…Analysis of sedimentary matter obtained by melting of sea ice gives important materials also. These studies made possible to reveal one unexpected source of glacial sediments -aeolian (Darby et al, 1974;Lisitzin, 2002;Shevchenko et al, 2002;Shevchenko, 2010;Chewings et al, 2014;Miller et al, 2015). The main feature of aeolian supply here is that aeolian material is deposited mostly during polar winter at low temperatures.…”

“…The dominant sedimentary process in most fjords is sedimentation from the brackish plumes rich in suspended particulate matter that emerges from either glacier-fed river mouths or tidewater cliff. Modern glacial-marine environments are widely spread in the Antarctic, Alaska, Greenland, Baffin Island, British Columbia, Svalbard, Norway, Novaya Zemlya, and Severnaya Zemlya (Drewry and Cooper, 1981;Elverhøi et al, 1983;Molnia, 1983;Cowan and Powell, 1991;Syvitski et al, 1996;Gilbert et al, 2003;Kehrl et al, 2011;Politova et al, 2012;Szczucinski and Zajaczkowski, 2012;Chewings et al, 2014;Miller et al, 2015).…”