Eolian and hydrothermal records in North and South Pacific pelagic clays.

In this thesis, the provenance of eolian and hydrothermal pelagic sediment in the Pacific Ocean was examined. Eolian dust deposited in the East-Central Pacific is dominated by an Asian component. Radiogenic isotopic compositions revealed three main detrital sources in the East-Central Pacific through factor analysis: factor 1 is associated with Asian-derived dust (epsilonNd), factor 2 with South and Central American volcanic sources (208Pb/ 204Pb, 207Pb/204Pb, 206Pb/ 204Pb), and factor 3 with North American sources (208Pb/ 206Pb, 207Pb/206Pb) while 87 Sr/86Sr shows a strong correlation with grain size. On this basis, Asian dust sources can be differentiated from American continental sources, and North and South/Central American sources can be distinguished from each other. These distinctions appear to have remained relatively constant over the last five million years. In the Southwest Pacific Basin, the age and provenance of eolian dust from a pelagic clay core at 40°S, 154°W (Marlin Rise) was examined. Fish teeth Sr isotope stratigraphy revealed a discontinuous 17.5 million year history of eolian sedimentation at this site. Radiogenic isotopes and XRD mineralogy showed little downcore variation, with considerable isotopic overlap with known Southern Hemisphere dust sources. A slight increase upcore in eolian grain size suggests strengthening atmospheric conditions during the late Cenozoic. Likely dust sources were Southeastern Australia and New Zealand, reflecting drying and cooling conditions in the Southern Hemisphere. The extracted detrital component of a metalliferous pelagic clay core from the Southwest Pacific Basin (32°S, 143°W) was also examined, showing a similar provenance to eolian deposits at Marlin Rise. Fish teeth Sr isotope stratigraphy and INAA trace element analysis of the bulk sediment revealed intense hydrothermal activity ∼30-25 Ma, decreasing to the present with proportionally greater terrigenous input. This part of the core records some of the lowest sedimentation rates found anywhere in the Pacific Basin (