Holocene sediments of the South Atlantic Ocean : the calcite compensation depth and concentrations of calcite, opal and quartz
The concentrations of calcite, opal and quartz have been measured in 113 South Atlantic core tops. The remainder of the total sample has been calculated as clay. A method for the quantitative determination of opal has been developed. Calcite is the dominant factor in South Atlantic sediments; its pa...
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| Other Authors: | , , , |
| Format: | Master Thesis |
| Language: | English unknown |
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Oregon State University
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| Online Access: | https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/4q77fv47k |
| Summary: | The concentrations of calcite, opal and quartz have been measured in 113 South Atlantic core tops. The remainder of the total sample has been calculated as clay. A method for the quantitative determination of opal has been developed. Calcite is the dominant factor in South Atlantic sediments; its pattern can be explained by bottom water circulation. Opal is primarily found in two bands - near the Equator and around 50° S. The distribution of opal resembles that of surface productivity. Quartz occurs near coastlines but also contains a significant ice- rafted component south of 35° S. Clay, probably consisting of kaolinite and illite, is principally found in the western Brazil Basin and extending southward into the Angola Basin from the Congo River mouth. The calcite compensation level is not meaningfully determined for the South Atlantic as a whole; it is necessary to divide data into basins. The levels obtained are: Brazil and northern Argentine Basins - 4800 m, Cape Basin - 5100 m, Angola Basin - 5400 m or deeper. Physico-chemical factors are more important than biological ones in determining the calcite compensation level. |
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