167 Preliminary Report


Figure 1. Location map of Leg 167 California Margin sites.

Figure 2. Site 1010 master columns showing examples of core recovery, simplified lithology, biostratigraphic and magnetostratigraphic zonations, and GRAPE density records.

Figure 3. Age vs. depth plot for Hole 1011B.

Figure 4. Interstitial water geochemistry of Coastal Transect sites (symbols from north to south: solid square, Site 1019; solid triangle, Site 1022; solid diamond, Site 1018; solid circle, Site 1017; open square, Site 1014; open triangle, Site 1013; open diamond, Site 1012; open circle, Site 1011). Alkalinity shows interplay of organic carbon diagenesis and interactions with the sediments. Calcium and magnesium show nonconservative profiles in the upper portion from authigenic mineral formation and ion exchange reactions. Deeper profiles are often conservative (linear correlation between Ca increase and Mg decrease), suggesting primary control by the diffusive influence of reactions in the underlying basalt. Silicate values are shown vs. depth and vs. temperature. The much narrower spread of values vs. temperature suggests biogenic opal solubility with temperature as primary control on concentration of dissolved silicate.

Figure 5. Thermal gradients at Leg 167 sites.

Figure 6. Hole 1014A magnetic susceptibility log data for passes 1 and 2. Value differences between the two passes are real and reflect changes in internal tool temperature as the tool warms in the borehole, an effect that can be corrected after processing. Broad-scale susceptibilty variations (2- to 3-m scale) are very similar to the core-based susceptibility measurements and can be used for core-log correlation purposes.

Figure 7. Obtaining a composite section. Smoothed (15 cm Gaussian) GRAPE bulk density data for the upper 250 on the mcd scale. Holes 1016A (lowermost) through Hole 1016D (uppermost curve) are vertically offset from each other by a constant (0.15 g/cm3). Cores are aligned relative to characteristic features.

Figure 8. (A) Shipboard 3.5-kHz precision depth recorder (PDR) record acquired during the Site 1016 presite survey; arrow marks the location where the beacon was dropped. Changes in (B) PWL velocity and (C) GRAPE density from Hole 1016A mapped to seismic reflectors.

Figure 9. Depth variations of (A) C37 alkenone abundance, (B) Uk37 value, and calculated sea-surface temperature (SST), and (C) total organic carbon (TOC) contents in sediments of Hole 1017B.

Figure 10. (A) Predicted opal content for Hole 1018A based on site-survey reflectance and opal data. Characteristic reflectance spectra of (B) diatom clay with silt, (C) clay with silt, and (D) nannofossil chalk with diatoms and clay.

Figure 11. Magnetostratigraphy (after 20-mT AF demagnetization) of sediments from Site 1021 (Delgada Fan). A complete magnetostratigraphy is obtained for the past 5.2 m.y.

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