A COMPARISON OF SEDIMENT CORES FROM THE DEEP SEA DRILLING PROJECT; A CLAY MINERALOGICAL AND GEOCHEMICAL ANALYSIS

The Robert Conrad and the Vema research vessels drilled cores from deep in the ocean and collected hundreds of samples up through the 1970s. The purpose of these missions was to collect drill cores and study them to more fully understand the source of the sediment. Comparative analyses were run on samples from the Atlantic, Bermuda, and the Gulf Coast to determine if there were any major differences.

T-tests show no statistical geochemical differences between the top and bottom, and no statistical difference between separate sites. Although these samples are statistically similar according to t-test results, the samples appear to differ when speaking in mineralogical terms. The origins of these sediment samples were determined based on differences in their clay mineralogy. High smectite percentages were shown within the Gulf samples; having the highest percentages closer to the mouth of the Mississippi Delta. Illite percentages were highest off the east coast of the USA. Chlorite/kaolinite percentages were highest in the Bermuda province, which reflected a potentially different source.

Understanding the overall differences in clay mineralogy of the cores from various provenances allows for a better understanding of the sediment sources. The clay mineralogy of the Atlantic margin cores shows a more mature, illite-rich sediment source, which is characteristic of a passive margin. The clay mineralogy of the Bermuda samples contained higher amounts of chlorite and kaolinite than the other provinces. This difference could be affected by aeolian sand deposits from the Sahara or could be the result of a local volcanic source. The clay mineralogy of the Gulf Coast cores contains the highest percentage of smectite when compared with the cores from the other provenances, which is a result of the influx terrestrial sediments from the Mississippi River.