Elemental and Isotope Geochemistry of Sediment from the Arctic Ocean

AOS_SR96_23
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However, no comprehensive study had been conducted in the Arctic Ocean.

Elemental and radiogenic isotope compositions of marine silicate sediment

are powerful tools for understanding the sediment source region, including its

location, general lithologic composition, age and crustal depth of exposure.

Upon identifying the source location and using sediment compositional varia-

tions to establish distribution patterns, it may be possible to reconstruct sedi-

ment transport pathways and infer transport mechanisms. This may provide

independent information concerning paleoceanographic or paleoatmospheric

circulation patterns and contribute to better paleoclimate reconstructions.

Surface sediments collected along the AOS-94 track (Mendeleyev Ridge,

Makarov Basin, Lomonosov Ridge, Amundsen Basin and Nansen Basin) have

been analyzed for major and trace elements via instrumental neutron activation

and x-ray fluorescence. We are completing RbSr, Nd and Pb isotope analyses

via thermal ionization mass spectrometry. We have analyzed the major and

trace element compositions for 20 other deep-ocean sediments (Canada Basin,

Northwind Ridge and Alpha Ridge), 3 sea ice samples and 19 samples of

sediment from rivers and shelf areas that are potential source regions (Queen

Elizabeth Islands, northern Canada, Kara Sea, Ob River, Yenisey River and

Pechora Sea).

Initial examination of the elemental data shows that all deep ocean sedi-

ment, except that from the Canada Basin, has much higher concentrations of

transition elements, such as Co and Ni, than does sea ice sediment and the

sediment samples from potential source regions. Transition elements are concen-

trated in hydrogenous oxide coatings, which accumulate on sediment parti-

cles at the sedimentwater interface in marine settings. Sediment from the

Canada Basin is deposited by turbidity currents at much higher sedimentation

rates than other areas of the central Arctic Ocean; hence, there is less accumu-

lation of hydrogenous oxide coatings on sediment from the Canada Basin.

Sediment from the Ob and Yenisey Rivers and the Kara Sea have much

higher concentrations of compatible elements (such as Cr and Sc) than all the

Bryce Winter, David Clark and Clark Johnson are with the Department of Geology and Geophysics at the

University of Wisconsin-Madison in Madison, Wisconsin, U.S.A.