Data report : major and trace element data for leg 202 sites 1233 and 1234
The exchange of waters between the Pacific and the Southern Oceans occurs along the eastern boundary of the South Pacific. Because water masses of the Antarctic provide a connection among the world's ocean basins, these water masses maintain the ability to influence changes in ocean circulation...
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| Format: | Article in Journal/Newspaper |
| Language: | English unknown |
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College Station, Tex. : Ocean Drilling Program, Texas A & M University
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| Online Access: | https://ir.library.oregonstate.edu/concern/articles/9306t415x |
| Summary: | The exchange of waters between the Pacific and the Southern Oceans occurs along the eastern boundary of the South Pacific. Because water masses of the Antarctic provide a connection among the world's ocean basins, these water masses maintain the ability to influence changes in ocean circulation and climate (Lynch-Stieglitz et al., 1996). One of the primary goals of Ocean Drilling Program (ODP) Leg 202 was to exploit the sediments underlying the southeast Pacific continental margin to ascertain how changes in past ocean circulation (i.e., water mass distributions) have affected global carbon, heat, and nutrient balances. In the southeast Pacific, oxygen-rich Antarctic Intermediate Water (AAIW) combines with (low oxygen) North Pacific Intermediate Water to produce a steep water column–dissolved oxygen gradient between depths of ~0.5 and 1 km. Shallower in the water column, the classical oxygen minimum zone (OMZ) impinges along the continental margin. These different water masses thus produce a "double" OMZ, with low-oxygen waters straddling the oxygen-rich AAIW. Given this distribution, changes in the intensity of water mass source functions through time should leave behind a depth transect of changing proxy distributions in response to changing bottom water oxygen concentrations. Sediments at Site 1233 are bathed by AAIW at a water depth of 838 m, whereas Pacific Central Water bathes the overlying waters at Site 1234. Site 1234 is located north of Site 1233 at 1015-m water depth. Because of rapid erosion of the high Andes, terrigenous sedimentation rates at these sites are in the range of 1–2 m/k.y. To assess changes in the reducing nature of these sediments through time, a number of geochemical indicators were determined. The solubility of uranium, molybdenum, cadmium, and vanadium decreases under the reducing conditions common along the continental margin seafloor; thus changes in their distribution may signify changes in the reducing character of the surface sediment. A number of other, primarily ancillary, ... |
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