Individual results of the geochemical analysis of the bulk sediment for each site studied during Leg 199 are recorded in the site chapters in this volume and, therefore, are not discussed in detail here. However, we illustrate the utility of bulk-sediment analysis by ICP-AES on board the JOIDES Resolution by presenting representative profiles of Si and Ca (weight percent of sediment) from Site 1218 as compared to observed lithologic units (Fig. F3). The concentration of silica increases in radiolarite and is relatively low in the nannofossil ooze and chalk. The geochemical analysis of the bulk sediment supports the identified lithologic units, and it also provides the concentrations of silica and calcium (for example) that become necessary when distinguishing nannofossil ooze and chalk. Small-scale variations in composition within each unit are also apparent.
When used in conjunction with the concentration of Ti or another terrigenous-associated metal, bulk-sediment geochemical analyses of Si and Ca can be used as a basis for normative calculations of the concentration of biogenic opal (biogenic SiO2) and calcium carbonate (CaCO3), as well as for initial estimations of biogenic and terrigenous MARs. Coupled with other shipboard analyses and a preliminary age model, each element characterized provides a first-order interpretation of influences on export production, climate, and terrigenous input (via Ti) in the equatorial Pacific (Fig. F4). This then provides a basis for more extensive, specific, and detailed shore-based research by the shipboard and shore-based parties.