Ocean Drilling Program (ODP) Site 1098 in the Palmer Deep, Antarctic Peninsula (Fig. F1) offers the potential to reconstruct a high-resolution record of marine Holocene climate in the Antarctic. A ~50-m-thick Holocene sequence of intermittently laminated diatom oozes and diatom-bearing muds was recovered at this site (Barker, Camerlenghi, Acton, et al., 1999). Sediments in the Palmer Deep document centennial-scale variation in marine productivity, expressed as meter-scale alternations between homogeneous bioturbated levels and laminated intervals with increased biogenic silica (Leventer et al., 1996; Domack et al., in press). Within the laminated intervals, light sediments alternate with diatom-rich laminae that are generally darker than the surrounding sediment. The diatom-rich laminae represent a seasonal signal of high productivity and/or diatom blooms (Leventer et al., 1996; Barker, Camerlenghi, Acton, et al., 1999; Pike et al., Chap. 18, this volume). The laminated portions of the Site 1098 record are therefore potentially varved and may offer the temporal resolution to reconstruct the extent of (sub)decadal climate variability in the Circum-Antarctic.
A correlation between increased diatom content and darker color implies that sediment color is a suitable proxy to compile such a high-resolution climate record, as color is a sediment property that can be measured easily. However, the shipboard color measurements generated with a Minolta spectrophotometer (Barker, Camerlenghi, Acton, et al., 1999) are based on one discrete measurement every 2 cm, a resolution too coarse to resolve color variation within the dark/light couplets. In addition, meter-scale cycles are also difficult to recognize (Acton et al., Chap. 5, this volume) because of scatter in the data resulting from undersampling of the centimeter-scale variation in color. In contrast, digital images of sediment surfaces, which we collected on shore after the cruise, provide the means to compile color records with the spatial resolution necessary to register lamina-scale color variation. Such ultrahigh-resolution time series have been used to unravel climatic history on annual to centennial scales represented in annually laminated sediments (Merrill and Beck, 1995; Schaaf and Thurow, 1995; Nederbragt and Thurow, in press). Here, we explore whether the continuous color time series derived from digital images provides a suitable proxy to describe variation in sediment composition at Site 1098. We also compare laminae thickness variation with published radiocarbon ages (Domack et al., in press) to determine the temporal resolution of the dark/light couplets to test whether laminated intervals are varved.