Ocean Drilling Program (ODP) Site 1017 on the southern California margin is ideally located to shed light on questions relating to interactions between the ocean and both high- and low-frequency climate changes. The site sits at 960 m water depth on the continental slope off Point Conception (Fig. 1) near the bottom of the modern oxygen minimum zone. Surface waters in the region are characterized by high primary and export production, a result of upwelling in the California Current system, and the area is located within the modern transition between the subarctic and subtropical zooplankton faunal zones. The chemical composition of sediments at Site 1017 is expected to be sensitive to variations in the provenance of terrigenous detritus and transport paths, both of which could be affected by changes in the California Current and/or terrestrial climate. Thus, sediments at this location can be expected to contain high-resolution records of changes in the intensity of the oxygen minimum zone, the intensity of surface circulation (Lyle, Koizumi, Richter, et al., 1997), ecological responses to climate shifts, and variability in detrital input through time.
Site 1017 also offers the prospect of adding to our understanding of global climatic teleconnections. Recent results from the analyses of cores in the Southern California Borderland Basins imply that high-frequency variability in intermediate-water renewal (Behl and Kennett, 1996) and sea-surface temperature (Mortyn et al., 1996) correlate very closely with Dansgaard-Oeschger cycles (Dansgaard et al., 1993) in central Greenland. To establish whether such millennial-scale climatic changes are manifested throughout the North Pacific or whether they are limited to the enclosed Southern California Borderland Basins, it is necessary to examine open-ocean, high-sedimentation-rate sites along the California margin, such as Site 1017.
Trace and minor element compositional information can provide a way to deduce changes in bottom-water oxygen level (Calvert and Pedersen, 1993), the sedimentary redox boundary depth (Crusius et al., 1996), and the history of biogenic deposition, all of which relate to the histories of upwelling, export productivity, and intermediate-water renewal. To set the stage for future exploration of such phenomena, we used a high-resolution suite of trace and minor element concentration data primarily to distinguish the relative contributions of diagenetic, biogenic, and detrital inputs and to establish the provenance of terrigenous detritus (Cullers, 1994). This is a necessary first step upon which subsequent paleoceanographic reconstructions will be based.