Site Summaries (continued) | Table of Contents

SITE SUMMARIES (continued)

Site: SEPAC-13B

Priority: 1
Position: 36°13.15´S, 73°40.91´W
Water Depth: 1040 m
Sediment Thickness: >300 m
Target Drilling Depth: 200 mbsf
Approved Maximum Penetration: 200 mbsf
Seismic Coverage: Survey 970312 (Revelle), Line CBA-3D-4, Shotpoint 585 (2248 on analog seismic). Note that no crossing line exists at this location. Although the site is approved for drilling as is, a short seismic survey will be done on approach to this site (crossing both SEPAC-13B and SEPAC-14A) using the JOIDES Resolution 80 in3 airgun.

Trackline map | Seismic Line 4 | Bathymetry map

Objectives: The objectives of Site SEPAC-13B are to provide a continuous sedimentary sequence to:

1. Assess Pleistocene history of a biological production in a coastal upwelling center near Concepción, Chile, which is sensitive to regional winds, with millennial-scale resolution.

2. Assess Pleistocene history of terrigenous sedimentation off central Chile to assess climate variability on land, with millennial-scale resolution.

3. Assess variations in the boundary between oxygen-rich AAIW (which is strongly developed near 700 m depth) and PCW (which is strongly developed deeper than 1200 m depth), using tracers of paleo-oxygen and paleonutrients.

4. If time is available, provide a dedicated hole for pore water measurements in the upper 100 m of the sediment column.

Drilling Program: Triple APC to refusal. Tensor orientation on APC cores. On a time-available basis, provide a fourth APC hole for purposes of sampling pore waters and other ephemeral properties and for reconnaissance-level sampling at the discretion of the SAC.

Logging and Downhole: None.

Nature of Rock Anticipated: Site SEPAC-13B is the thickest apparent accumulation of a slope basin in an active margin setting. A sediment core nearby recovered organic-rich muds. Sedimentation rates are probably high, expected to be >200 m/m.y. Seismic survey suggested widely varying sedimentation in the region, including some areas of net erosion.

Site Summaries (continued) | Table of Contents