Site Summaries
Site: PRU-3A
Priority: Primary
Position: 8°59.49'S, 79°54.35'W
Water Depth: 426 m
Sediment Thickness: >160 m
Target Drilling Depth: 160 m
Approved Maximum Penetration: 160 m
Seismic Coverage: Line H from the Yaquina Yaloc survey and multichannel line 2025, which
intersects the site and line 1900 which crosses Line 2025 ~7 km southwest of the site, same
position as ODP Site 684.
See seismic line.
Objectives:
1) Examine microbial communities, activity, and survival strategies in a "normal" upwelling-zone
methanogenic sedimentary sequence for comparison with other shallow water sites where a
subsurface brine flow appears to disrupt the pore water chemistry. This site shows no evidence
of the brine incursion.
2) Identify the methanotrophic communities of deeply buried marine sediments.
Drilling Program: APC to refusal, XCB to total depth (TD). At least two holes, possibly three. Possible MDCB/RCB coring to improve recovery. Possible PCS deployment. May require additional mudline cores
Logging and Downhole Program: APC-temperature, DVTP, and APC methane tool.
Nature of Rock Anticipated: Diatomaceous and terrigenous mud, silt, and sand.
