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Geochemical records are presented for five sediment cores from basins on the continental shelf of Mac. Robertson Land, East Antarctica. The cores contain 2-4 m thick sequences of hemipelagic, siliceous mud and ooze (SMO) deposited under seasonally open marine conditions. The inner and middle shelf SMO sequences are massive dark olive green material, whereas the outer shelf SMO sequences are dark olive material interspersed with light olive green layers similar to1-10 cm thick. The biogenic material is dominated by marine diatoms including Fragilariopsis curta, Fragilariopsis cylindrus, and Chaetoceros spp. in the dark-colored SMO and Corethron criophilum in the light-colored layers. Radiocarbon dates suggest that the cores provide continuous accumulation records extending from < 1 kyr before present (B.P.) back as far as 4-15 kyr B.P., with estimated accumulation rates of 0.07-5 mm yr(-1). The three core records from the middle and outer shelf suggest six episodes of increased accumulation of biogenic material at 5.5 kyr B.P. tall three cores), 1, 2, and 6.2 kyr B.P. (two of the three cores), and 3.8 and 10.8 kyr B.P. tone core), most of which coincide with Corethron layers. We interpret these features as the result of enhanced diatom production over the outer shelf, possibly related to climatic warm periods. The absence of such features in the inner shelf core records is thought to reflect a relatively constant level of seasonal diatom production in adjacent waters maintained by a coastal polynya.

Original Publication Citation

Sedwick, P.N., Harris, P.T., Robertson, L.G., McMurtry, G.M., Cremer, M.D., & Robinson, P. (2001). Holocene sediment records from the continental shelf of Mac. Robertson Land, East Antarctica. Paleoceanography, 16(2), 212-225. doi: 10.1029/2000pa000504