Site Summaries (continued) | Table of Contents

SITE SUMMARIES (continued)

Priority: 2 (Alternate site to Site NAZCA-17A)
Position: 17°02.10´S, 78°06.54´W
Water Depth: 2930 m
Sediment Thickness: 300 m
Target Drilling Depth: 300 mbsf
Approved Maximum Penetration: 350 mbsf
Seismic Coverage: Sediment Cover TWTT = 0.40 s (300 m)
Primary Line: 970327 (Revelle), Line NAZ-6A-1, 0043z, SP505
Crossing Line: 970327 (Revelle), Line NAZ-6A-3, 0616z, SP433

Trackline map | Seismic Line 1 | Seismic Line 3 | Bathymetry map

Objectives: The objectives at Site NAZCA-14A are to provide a continuous sedimentary sequence to:

1. Monitor the offshore extent of the productivity gradient in the Eastern Boundary Current during Pleistocene time, through comparison to NAZCA-17A.

2. Provide an ancient (early Neogene) record of the subtropical gyre that has not been deeply buried.

3. Monitor PCW (backtracking into intermediate water depths in early Neogene time).

Drilling Program: Triple APC to refusal. Tensor orientation on APC cores. Single XCB to extend one hole to basement or refusal (expected penetration ~300 mbsf).

Logging and Downhole: Triple combo, third-party Lamont MGT, FMS/sonic, GHMT.

Nature of Rock Anticipated: Site survey core suggests foram-nannofossil ooze. Pleistocene section contains siliceous fossils, lithified at depth. Basement ages likely near 40 Ma in this region, and sediment thickness of ~300 m suggests average sediment accumulation of ~8 m/m.y.. A rhythmic sequence of >40 reflectors through the section suggests that this area will record significant changes in climate in the local lithology. Basement likely composed of hotspot volcanics, but may be either erosion surface from subaerial exposure, or drowned reef.

Site Summaries (continued) | Table of Contents