Figure F1. Leg 202 drill sites span a broad latitudinal range from southern Chile to Central America. Site 1232 is in the Chile Basin; Sites 12331235 are on the Chile margin; Sites 1236 and 1237 are on Nazca Ridge; Sites 1238 and 1239 are on the Carnegie Ridge; Site 1240 is in the Panama Basin; and Sites 1241 and 1242 are on Cocos Ridge.
Figure F2. Summary stratigraphic columns document cored and drilled intervals, ages, and water depths at Sites 12321242. B = Basin.
Figure F3. Upper-ocean currents off the west coast of South America. NECC = North Equatorial Countercurrent, EUC = Equatorial Undercurrent, PCC = Peru-Chile Current, GU = Gunther Undercurrent.
Figure F4. Site locations on modern annual average values of (A) sea-surface temperature (°C), (B) sea-surface phosphate (µM), and (C) sea-surface salinity (PSU).
Figure F5. Cross section of subsurface water masses in a transect through the drilling sites, characterized by (A) dissolved oxygen (mM), (B) dissolved phosphate (µM), and (C) salinity. AAIW = Antarctic Intermediate Water, NPIW = North Pacific Intermediate Water, PCW = Pacific Central Water, GU = Gunther Undercurrent, CPDW = Circumpolar Deep Water.
Figure F6. Plate tectonic backtrack of Leg 202 drill sites. Large circles = the modern location, and successive circles = the backtrack position relative to South America at 1-m.y. intervals. Number at the end of each backtrack path = oldest age of recovered sediment at each site.
Figure F7. Core-log integration. Pervasive meter-scale rhythmic variations were observed in borehole resistivity and core density logs at Sites 1238, 1239, and 1241. Such variability is likely associated with fluctuations in the fractions of carbonate and biogenic opal in the sediments. The Formation MicroScanner (FMS) image of the borehole at Site 1241 is shown to the right of the 64-button average (5-point smoothing) in red. The similarity of the smoothed FMS and the lower-resolution gamma ray attenuation (GRA) bulk density record (blue) in cores from Hole 1241B suggests that borehole logs will provide a relatively continuous proxy record of lithologic variability and will provide for detailed integration of depth scales between the borehole and core logs. Eld = equivalent logging depth.
Figure F8. Comparison of natural gamma radiation data from core logging and downhole logging. Note that the data from two downhole tools (HSGR and MGT) and the MST-NGR correlated very well at meter scale throughout and at submeter scale over most intervals.
Figure F9. Comparison of gamma ray attenuation (GRA) bulk density data from core logging and downhole logging. Note the excellent correlation of variations in magnitude and depth at meter scale. Minor discrepancies at submeter scale may be the result of core disturbance or borehole irregularities.
Figure F10. Relative changes in apparent depth offsets (in the mcd scale) of sequential cores vs. time of coring operation compare well with predictions of tidal sea level oscillations at Site 1240.
Figure F11. Reflectance spectroscopy-derived calcium carbonate and total organic carbon (TOC) contents compared to directly measured quantities at Site 1237.
Figure F12. PSVs at Site 1233, illustrating replication of declination variability in different holes and the assembly of a spliced PSV record with named events from 0 to 30 mcd.
Figure F13. PSVs at Site 1234, illustrating replication of declination variability in different holes, and the assembly of a spliced PSV record, with named events from 0 to 15 mcd.
Figure F14. Variations in paleomagnetic declination (psu) (top), inclination (middle), and normalized relative paleointensity (bottom) at Chile margin, Site 1233, from 0136 mcd (inferred ~0140 ka). Note the inferred Laschamp Excursion (~41 ka) near 68 mcd, which implies an average sedimentation rate of nearly 170 m/k.y. from the core top to this level. PSV = paleomagnetic secular variation, BP = before present.
Figure F15. Variations in paleomagnetic declination (top), inclination (middle), and renormalized relative paleointensity (bottom) at Chile margin, Site 1233, from 1565 mcd (inferred ~1140 ka). Note the well-defined rhythmic variations in all parameters. PSV = paleomagnetic secular variation, BP = before present.
Figure F16. Comparison of paleomagnetic inclination, declination, and renormalized relative paleointensity at Sites 1233 and 1234. PSV = paleomagnetic secular variation.
Figure F17. Age-depth plot for Sites 1237 and 1241 based on calcareous nannofossil, planktonic foraminifer, and diatom datums. Results for Site 1236, which has similar science objectives and is also located on Nazca Ridge as Site 1237, are shown for comparison.
Figure F18. Leg 202 linear sedimentation rates for Sites 12361242, 030 Ma.
Figure F19. Linear sedimentation rates since 15 Ma for (A) Leg 202, Sites 12361242, and (B) Leg 138, Sites 844, 846, and 848.
Figure F20. Interstitial sulfate concentrations vs. depth. A. All sites. B. Sites with complete sulfate reduction, upper 100 mcd. Values below detection limits (typically 1 mM) are plotted at zero.
Figure F21. Interstitial calcium and magnesium/calcium profiles vs. depth. A,İC.İCalcium and magnesium/calcium profiles for sites with limited to moderate sulfate reduction. B,İD.İCalcium and magnesium/calcium profiles for sites with complete sulfate reduction. Note vertical scale changes from C to D.
Figure F22. Interstitial chloride vs. depth for Chile margin sites (1233, 1234, and 1235).
Figure F23. Interstitial profiles of sulfate, alkalinity, phosphate, and ammonium vs. depth for Panama Basin site (1240).
Figure F24. A. Quartz distribution in surface sediments of the subtropical southeast Pacific, expressed as weight percentage (carbonate- and opal-free basis, reproduced from Molina-Cruz, 1977). Gray arrows indicate trade winds. Sites 1236, 1237, 1238, and 1239 are shown with their plate tectonic backtrack. B.İSiliciclastic accumulation rates and hematite peak height at Sites 1236 (red line) and 1237 (blue line). The accumulation rates of siliciclastics were estimated as (100% wt% CaCO3 wt% organic matter) x sedimentation rate x dry bulk density. The shipboard magnetostratigraphy and biostratigraphy were used to calculate sedimentation rates that were smoothed to avoid overinterpretations of the preliminary age model. Note that the siliciclastic accumulation rates at Site 1237 include biogenic silica in the interval of the last ~8 m.y. Based on smear slide data (that overestimate weight percent biogenic opal), biogenic opal values increased from ~1 to 10 vol% over the last 8 m.y. This, however, will not change the general trends observed in the siliciclastic accumulation rate record that is used as a proxy for dust flux. The hematite peak height is derived from color reflectance spectra and serves as a proxy for changing concentrations of hematite.
Figure F25. A. Carbonate accumulation rates at Sites 12361238 and 1241, calculated as the product of weight percent CaCO3, sedimentation rate, and dry bulk density. The shipboard magnetostratigraphy and biostratigraphy were used to calculate sedimentation rates that were smoothed to avoid overinterpretations of the preliminary age model. B. Annual chlorophyll-a concentrations (mg/m3; http://seawifs.gsfc.nasa.gov), site locations, and tectonic backtrack. Red dots = paleoposition of sites from ~4 to 8 Ma.
Figure F26. Ash frequency was calculated as first derivative of the cumulative number of ash horizons plotted vs. age. Red lines = volcanic ash frequency (number/m.y.), and green bars = thickness of each ash layer (cm) at Sites 12371242.
Figure F27. Weight percentage carbonate, weight percentage organic carbon, foraminifer abundance (Rİ=İrare, F = few, C = common, A = abundant) and preservation (P = poor, M = moderate, G = good), and the percentage benthic foraminifers at Site 1241. The orange box indicates the time interval of the Miocene carbonate crash observed in the eastern equatorial Pacific.
Figure F28. Evolutive spectra of the lightness parameter L* at Site 1239 (which tends to mimic carbonate content of the sediments) using preliminary shipboard age models. Warm colors indicate greater concentrations of variance within a frequency band.
Figure F29. Sites 12321235 are located at the southernmost reaches of the Peru-Chile Current system, in the transition between the subtropical and subpolar gyres. A. Contours of annual mean surface water temperatures. Arrows indicate surface water currents. ACC = Antarctic Circumpolar Current, PCC = Peru-Chile Current, PCCC = Peru-Chile Countercurrent, CFW = Chilean Fjord Water, CCC = Coastal Countercurrent. B. Salinity contours showing influx of Chilean Fjord Water (CFW). Site 1233 is best located to monitor low-salinity surface waters that advect northward, a measure of the strength or location of the westerly winds. Sites 1234 and 1235 are located to the north, within the eastern boundary current setting, in an upwelling center off of Concepción.
Figure F30. Locations of Sites 12331235 on subsurface oxygen. Circles mark the current site locations relative to the oxygen-poor Gunther Undercurrent (GU) and the relatively oxygen-rich Antarctic Intermediate Water (AAIW). Vertical bars on the sites indicate the likely effect of last glacial maximum sea level fall of ~130 m on the position of the sites relative to the sea surface. PCW = Pacific Central Water.
Figure F31. Shipboard correlation of Sites 1233, 1234, and 1235 based on biostratigraphic (<260 ka for all sites) and magnetostratigraphic (e.g., location of Laschamp Event at ~41 k.y.) evidence as well as long-term patterns in magnetic susceptibility, organic carbon, and calcium carbonate concentrations. These data suggest that all three sites will contain viable records of century- to millennial-scale climate change. IU = instrument units.
Figure F32. Millennial-scale variability at Site 1233. Magnetic susceptibility and diatom abundance plotted on a preliminary age scale for the interval 0 to 45 k.y. The age scale is based on Holocene age control points derived from a correlation of the magnetic susceptibility records between Site 1233 and AMS-14C dated core GeoB 3313-1 (Lamy et al., 2001) and the location of the Laschamp Event. All ages are calendar years are BP and are linearly interpolated between the dates. The data are compared to the GISP2 ice core in Greenland (Grootes et al., 1993) and the Byrd ice core in Antarctica (Bender et al., 1999). SMOW = oxygen isotopic composition of standard mean ocean water.
Figure F33. Seismic profile across Site 1232 (proposed Site SEPAC-9A), shotpoint 686 (survey CBA-3A, line 3, shot within 05040720 UTC, 08 March 1997). (Mix et al., 1997).
Figure F34. Core recovery, lithology, age, and physical and chemical data summary, Site 1232.
Figure F35. Digital parasound profile, Site 1233 (Hebbeln et al., 1995).
Figure F36. Analog 3.5-kHz profile acquired with the JOIDES Resolution during the approach to Site 1233, 12 April 2002. Depths are represented at 1500 m/s. Reflector numbers appear in boxes.
Figure F37. Core recovery, lithology, age, and physical and chemical data summary, Site 1233.
Figure F38. Age-depth tie points and sedimentation rates, Site 1233. For the top 9 mcd, the points were obtained by direct correlation of Site 1233 magnetic susceptibility data to those of an accelerator mass spectrometry (AMS) 14C-dated sediment core (GeoB3313-3; Lamy et al., 2002). The other points were obtained by correlating a preliminary paleomagnetic intensity record with that published by Stoner et al., in press.
Figure F39. Swath bathymetry of Chilean margin segment, including Sites 1234 and 1235.
Figure F40. Seismic profile across Site 1234 (proposed Site SEPAC-13B), shotpoint 585 (survey CBA-3D, line 4, shot within 21000018 UTC, 12 March 1997) (Mix et al., 1997).
Figure F41. Core recovery, lithology, age, and physical and chemical data summary, Site 1234.
Figure F42. Seismic profile across Site 1235 (proposed Site SEPAC-14A), shotpoint 268 (survey CBA-3D, line 15, shot within 09481051 UTC, 14 March 1997) (Mix et al., 1997). Note the preferred site at shotpoint 295.
Figure F43. Core recovery, lithology, age, and physical and chemical data summary, Site 1235.
Figure F44. Magnetic susceptibility and chroma (a*) records from the three holes drilled at Site 1235. Green bars = locations of greenish intervals, yellow bars = positions of associated bioturbated intervals, green diamonds = depth of carbonate nodules. The intervals of abrupt change in the physical properties may represent episodes of seafloor dysoxia.
Figure F45. Tectonic backtrack paths for Sites 1236 and 1237. Contours are mean annual sea-surface temperatures. PCC = Peru-Chile Current, SEC = South Equatorial Current.
Figure F46. Seismic profile across Site 1236, shotpoint 366 (survey NAZ-1B, line 5, shot within 21002250 UTC, 22 March 1997) (Mix et al., 1997).
Figure F47. Core recovery, lithology, age, and physical and chemical data summary, Site 1236.
Figure F48. Seismic profile across Site 1237, shotpoint 589 (survey NAZ-3B, line 4, shot within 12341529 UTC, 29 March 1997) (Mix et al., 1997).
Figure F49. Core recovery, lithology, age, and physical and chemical data summary, Site 1237.
Figure F50. Color measurements at Site 1237 (spliced record) plotted in the a*-b* plane (upper left) and close ups of the L*-a* (upper right), L*-b* (lower left), and a*-b* (lower right) color planes. Measurements plot in two main regions in the a*-b* color plane: the generally greenish sediments of Unit I and Subunit IIA group in the second quadrant, whereas the reddish sediments of Subunit IIB cluster more tightly in the first quadrant. Three populations (IIB1, IIB2, and IIB3) can be distinguished within the red part of the color space.
Figure F51. Seismic profile across Site 1238 (Lyle et al., 2000).
Figure F52. Tectonic backtrack paths for Sites 1238 and 1239. Contours are mean annual sea-surface temperatures.
Figure F53. Core recovery, lithology, age, and physical and chemical data summary, Site 1238.
Figure F54. Preliminary time series analysis results from Site 1238 based on shipboard biostratigraphic age model. Time series and corresponding spectra from 0 to 1 Ma (assuming a linear sedimentation rate between 0.0 and 58.2 mcd, as inferred from one biostratigraphic datum in this interval) of (A, B) magnetic susceptibility; (C, D) GRA bulk density; and (E, F) lightness. Orbital frequencies are denoted by gray bands. The concentration of variance near the known orbital frequencies suggests that meter-scale lithologic banding is associated with orbital-scale climate variability.
Figure F55. Seismic profile across Site 1239.
Figure F56. Core recovery, lithology, age, and physical and chemical data summary, Site 1239 (Lyle et al., 2000).
Figure F57. Swath bathymetry of Panama Basin segment, including Site 1240.
Figure F58. Seismic profile across Site 1240 (Mix et al., 2000).
Figure F59. Core recovery, lithology, age, and physical and chemical data summary, Site 1240 (Lyle et al., 2000).
Figure F60. Seismic profile across Site 1241.
Figure F61. Core recovery, lithology, age, and physical and chemical data summary, Site 1241 (Lyle et al., 2000).
Figure F62. Seismic profile across Site 1242.
Figure F63. Core recovery, lithology, age, and physical and chemical data summary, Site 1242 (Lyle et al., 2000).Table of Contents