Site Summaries (continued) | Table of Contents

SITE SUMMARIES (continued)

Site: NAZCA-10A

Priority: 1
Position: 21°21.54´S, 81°26.16´W
Water Depth: 1323 m
Sediment Thickness: 200 m
Target Drilling Depth: 200 mbsf
Approved Maximum Penetration: 250 mbsf
Seismic Coverage: Sediment Cover TWTT = 0.26 s (200 m)
Primary Line: 970322 (Revelle), Line NAZ-1B-5, 2201z, SP366
Crossing Line: 970322 (Revelle), Line NAZ-1B-2, 1402z, SP267
Crossing Line: 970322 (Revelle), Line NAZ-1B-1, 1119z, SP314

Trackline map | Seismic Line 1 | Seismic Line 2 | Seismic Line 5 | Bathymetry map

Objectives: The objectives at Site NAZCA-10A are to provide a continuous sedimentary sequence to:

1. Monitor changes in the boundary between Pacific Deep Water and Antarctic Intermediate Water (AAIW) (or in older intervals, the core of AAIW), in a subtropical area away from the continental margin, where primary production is low. Because sedimentation rates are low (<10 m/Ma), this is expected to be a relatively low-resolution record.

2. Assess climate changes of the southern subtropical Pacific during Neogene and perhaps into Oligocene time (basal age 30-35 Ma, assuming basalt hotspot crust‹younger if erosional surface or drowned reef).

Drilling Program: Triple APC to refusal. Tensor orientation on APC cores. If needed, single XCB to deepen one hole to basement or XCB refusal (expected total penetration ~200 mbsf).

Logging and Downhole: None.

Nature of Rock Anticipated: Pelagic foraminiferal ooze with nannofossils. Deeper intervals may be partly lithified. Some hiatuses may be present. Acoustic basement may be coral or an erosion surface on hotspot volcanics, as some parts of the shallow rise crest appear to be flat (sea level) erosional features.

Site Summaries (continued) | Table of Contents