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SITE SUMMARIES (continued)

Site: SEPAC-19A

Priority: 2 (to be drilled if time is available, based on results at SEPAC 13B and SEPAC-14A. This site is considered an alternate to SEPAC-13B)
Position: 41°00.0´S, 74°27.0´W
Water Depth: 851 m
Sediment Thickness: imaged to 80 m
Target Drilling Depth: 80 mbsf
Approved Maximum Penetration: 80 mbsf (PPSP requests review of additional crossing lines)
Seismic Coverage: Sonne 1995, Parasound Line GeoB41/43 (Hebbeln et al., 1995, penetration of 0.11 s = >80 m). No seismic reflection data exists for this site other than Parasound. No crossing line exists for this site. Although the site is approved for drilling as is, a short survey will be done prior to drilling this site using the JOIDES Resolution 3.5 kHz profiler.

Seismic Line

Objectives: The objectives of Site SEPAC-19A are to provide a continuous sedimentary sequence to:

1. Monitor changes in the coastal upwelling center near Valdivia, Chile, which is sensitive to regional winds. The site is poleward of the strongest upwelling zone, within the transition zone between poleward-flowing Cape Horn Current (associated with net downwelling) and the equatorward-flowing Humboldt Current (associated with net upwelling). Thus, variations in upwelling here may reflect the latitudinal position of the Westerly Winds, which control the position of the transition zone.

2. Assess variations in terrigenous sedimentation that respond to climate changes near the northern boundary of the Chilean fjords.

3. Monitor water mass properties within the relatively oxygen-rich AAIW (strongly developed near 700 m depth).

Drilling Program: Triple APC to refusal or maximum approved penetration. Tensor orientation on APC cores.

Logging and Downhole: None.

Nature of Rock Anticipated: SEPAC-19A is at 851 m depth in a sediment-filled tectonic slope basin. Sediments are likely rapidly accumulating organic-rich clays dominated by a terrigenous component. Basement is likely continental crust.

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