Mineral Assemblages at IODP Sites U1387 and U1389, Gulf of Cadiz: Definition by Principal Component Analysis and Interpretation of Their Geologic Significance
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. School of Earth Sciences Senior Theses; 2015
The Gulf of Cadiz and the West Iberian margin were the location where Expedition 339 of the Integrated Ocean Drilling Program (IODP) collected sediment cores to better understand the Mediterranean Outflow Water (MOW) and its history. Sediment from Sites U1387 and U1389 was analyzed by X‐ray diffraction (XRD) method aboard the JOIDES Resolution to determine the bulk mineralogy at the two sites. In this study, shipboard data were processed using Paleontological Statistics (PAST) software to identify mineral assemblages using principal components analysis. The mineral assemblages were defined by covarying minerals, and were used to determine sediment provenance. At Site U1387, the three most important principal components defined five mineral assemblages that consisted of plagioclase, dolomite, kaolinite, K‐feldspar, augite, aragonite and chlorite. At Site U1389, the three most important principal components defined six mineral assemblages made up of plagioclase, dolomite, chlorite, and aragonite. Principal Component 2 at Site U1387 and Principal Component 1 and 3 at Site U1389 are indicative of a relationship between marine biogenic vs. terrigenous detrital sediment supply, and the other principal components identify various assemblages of detrital terrigenous minerals. The results generally identified a local provenance from the Guadiana and Guadalquivir Rivers, with erosion of exposed beaches and cliffs as other possible sources of sediment supply. This supports the 3 conclusion that Gulf of Cadiz sediments have been supplied from a variety of nearby areas, with transport and deposition influenced by many environmental and geological influences.
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