Site Summaries (continued) | Table of Contents

SITE SUMMARIES (continued)

Priority: 1
Position: 1°52.31´S, 82°46.94´W
Water Depth: 2223 m
Sediment Thickness: 480 m
Target Drilling Depth: 480 mbsf
Approved Maximum Penetration: 500 mbsf
Seismic Coverage: Sediment thickness: 0.582 s (480 m)
Primary Line: 2000 NEMO-3 (Melville), CAR-2 survey Line 3, JD150 23:19:01z (SP4137)
Crossing Line: 2000 NEMO-3 (Melville), CAR-2 survey Line 6, JD151 10:56:08z (SP3940)

Seismic Line 3 | Seismic Line 6 | Bathymetry map

Objectives: The objectives at Site CAR-2C are to provide a continuous sedimentary sequence to:

1. Assess Neogene (0-17 Ma) history of surface water masses, including the eastern reaches of the equatorial cold tongue, upwelling, and paleoproductivity off Ecuador. Because of the relatively shallow depth of CAR-2, the sediments should be above the lysocline and carbonate dissolution should be controlled by the relative rates of carbonate rain from the surface waters and organic carbon degradation within the surface sediments.

2. Assess subsurface water masses (PCW) at the sill depth of entry into Panama Basin (shallower in older interval).

3. Assess physical properties and structural information in the sediment section, which appears to be creeping downhill ("mud glacier") on the southeastern margin of the Carnegie Ridge. Seismic reflection profiling suggests a deformed layer about 250 m deep within the section.

Drilling Program: Triple APC to refusal. Tensor orientation on APC cores. Single XCB to extend one hole to basement or refusal (expected penetration ~480 mbsf).

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

Nature of Rock Anticipated: Site survey core is siliceous nannofossil ooze, highly mottled. Expect nannofossil ooze throughout section, with occasional layers (for example, ash layer L, 230 ka [Ninkovitch and Shackleton, 1975] was found between 10.42 and 10.60 mbsf). By analogy with ODP Leg 138, expect some siliceous oozes at depth. Greater lithification at depth‹chalk and minor chert possible.

Site Summaries (continued) | Table of Contents