10.1594/PANGAEA.744626
Morford, J L
J L
Morford
0000-0003-4882-6576
Russell, Ann D
Ann D
Russell
0000-0002-8136-5006
Emerson, Steven R
Steven R
Emerson
(Table 2) Trace metal concentrations in ODP Hole 169-1033B
PANGAEA
2001
Sample code/label
DEPTH, sediment/rock
Depth, composite revised
Method comment
Cadmium
Molybdenum
Uranium
Vanadium
Manganese
Iron
Aluminium
Rhenium
Drilling/drill rig
DSDP/ODP/IODP sample designation
ICP-MS, Perkin-Elmer, SCIEX Elan 5000
ICP-MS, see further details
Leg169S
Joides Resolution
Ocean Drilling Program (ODP)
1996-08-19T16:30:00
en
Supplementary Dataset
10.1016/S0025-3227(00)00160-2
670 data points
text/tab-separated-values
Creative Commons Attribution 3.0 Unported
We measured the concentrations of redox-sensitive trace metals (Mn, V, Mo, U, Cd and Re) in sediments from ODP Leg 169S Hole 1033B in Saanich Inlet, British Columbia, to determine changes in redox conditions associated with the onset of laminated sediments at ~12.5 kyr. The most striking result is a large peak in authigenic Re along with detrital levels of Mo at the glacial terrigenous clay-diatomaceous sediment transition. In contrast, the underlying glacial terrigenous clay, which extends throughout the bottom section of the core, is chemically similar to detrital concentrations, either Cowichan River particulates or average shale values. These data suggest a period of oxic bottom waters but reducing pore-waters. This could be due to the dramatic transformation of Saanich Inlet during the late deglaciation from an open bay to an inlet, which restricted circulation and slowed bottom water oxygen renewal. A peak and gradual increase in authigenic Mn in younger sediments subsequent to the Re peak suggests that increasingly oxic conditions followed the authigenic enrichment in Re. These conditions could be connected to the Younger Dryas cooling period, which was coincident with an increase in well oxygenated upwelled waters on the west coast of North America that form the bottom waters of Saanich Inlet.
Metal concentrations in a gray clay bed (~11 kyr) are similar to their concentrations in the glacial terrigenous clay, implying that they have a common source. Authigenic enrichments of Re with little authigenic Mo and Cd suggest that before the deposition of this bed, bottom waters were oxic and pore-water oxygen was consumed in the top centimeter or less. Laminations above the clay layer suggest anoxic conditions, which are also indicated by higher authigenic Mo and Cd and slightly lower Re/Mo ratios in these sediments. The basin remained mostly anoxic after the gray clay was emplaced, as seen by continuous authigenic enrichment of the redox-sensitive trace metals. These results are consistent with increased stratification of the water column, brought about by an influx of fresh water to the basin by a large flood.
Sediment depth given in meters below sea-floor (mbsf).
Supplement to: Morford, J L; Russell, Ann D; Emerson, Steven R (2001): Trace metal evidence for changes in the redox environment associated with transition from terrigenous clay to diatomaceous sediment, Saanich Inlet, BC. Marine Geology, 174(1-4), 355-369
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Coastal waters of SE Alaska