Chemical composition of northwest Nazca Plate sediments

The samples used for this study are a subset from almost 200 surface samples from the western Nazca plate analyzed during the IDOE Nazca Plate Project. The subset was selected to provide coverage of the major physiographic units north of the Sala y Gomez Ridge and to encompass the major sediment types defined by factor analysis of selected major- and minor-element concentrations. The chemical data used in this study consist of bulk-sediment analyses by atomic absorption spectrometry. Samples were dissolved in Teflon-lined bombs using HF, HNO3, and HC1 heated to 125°C. H3BO3 was added to neutralize the HF and to dissolve insoluble fluorides. The precision of these analyses varies from less than 1% for the major elements and trace elements with concentrations greater than 200 ppm to approximately 20% for trace elements in the CaCO3-rich samples. For Fe,Cu,Ni and Zn the leached and residual parts listed in the original table have been reconciled.