Site Summaries (continued) | Table of Contents

SITE SUMMARIES (continued)

Site: NAZCA-16A

Priority: 2 (alternate to Site NAZCA-17A)
Position: 16°08.04´S, 76°58.62´W
Water Depth: 2244 m
Sediment Thickness: 320 m
Target Drilling Depth: 320 mbsf
Approved Maximum Penetration: 350 mbsf
Seismic Coverage: Sediment Cover TWTT = 0.42 s (320 m)
Primary Line: 970328 (Revelle), Line NAZ-2B-2, 0713z, SP643
Crossing Line: 970328 (Revelle), Line NAZ-2B-5, 1217z, SP492

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

Objectives: The objectives at Site NAZCA-16A are to provide a continuous sedimentary sequence to:

1. Monitor the shallow end-member of a depth transect of the heavily sedimented eastern Nazca Ridge, which cuts across the deep-water masses and monitors a carbonate dissolution gradient.

2. Monitor the Pleistocene core of the Humboldt Current at low latitudes with well-preserved fauna.

3. Monitor surface water properties of the subtropical South Pacific during 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 ~320 mbsf).

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

Nature of Rock Anticipated: Site survey cores recovered foram-nannofossil ooze with common radiolarians and diatoms. Sediment thickness of ~320 m suggests average sediment accumulation of ~8 m/m.y., although based on sediment cores in the region late Pleistocene sedimentation rates are probably 20-30 m/m.y. A rhythmic sequence of >50 reflectors through the section suggests that this area will record significant changes in climate in the local lithology.

Site Summaries (continued) | Table of Contents