Site Summaries (continued) | Table of Contents


Site: CAR-1C

Priority: 1
Position: 00°40.319´S, 82°04.853´W
Water Depth: 1423 m
Sediment Thickness: 513 m
Target Drilling Depth: 513 mbsf
Approved Maximum Penetration: 550 mbsf
Seismic Coverage: Sediment cover: Two-way traveltime (TWTT) = 0.604 s (513 m)
Primary Line: 2000 NEMO-3 (Melville) CAR-1 survey Line 6, JD153 07:18:23z (SP2626; CDP 6427). Crossing Line: 2000 NEMO-3 (Melville) CAR-1 survey Line 12.

Seismic Line 6 | Seismic Line 12 | Bathymetry map

Objectives: The objectives at Site CAR-1C are to provide a continuous sedimentary sequence to:

1. Study the Pleistocene history of upwelling and paleoproductivity within the South Equatorial Current off Ecuador.

2. Monitor the composition of basal intermediate waters to monitor the South Equatorial Current.

Drilling Program: Triple APC to refusal. Tensor orientation on APC cores. Single XCB to extend one hole to basement or refusal (expected penetration ~520 mbsf).

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

Nature of Rock Anticipated: A site survey piston core consists of foram ooze with nannofossils, highly mottled. There is a subtle alteration of colors downcore, which probably represents orbital cyclicity. Two ash layers were found in the core at 5.4 m (?Ash D, 84 ka) and at 11.11 m (?Ash L, 230 ka), indicating late Pleistocene sedimentation rates of 50-60 m/m.y.. Similar lithologies are expected downcore, with increasing lithification. By comparison of the seismic section to that developed for the cores from Leg 138 and other sites to the west (Mayer et al., 1986; Bloomer et al., 1995), we estimate basal ages at 15 Ma and long-term sedimentation rates at 35 m/m.y.. An exception is the late Miocene-early Pliocene interval between reflectors R3 and R6. This interval has a sedimentation rate roughly twice as high as the others. The late Miocene-early Pliocene is the interval of enhanced equatorial productivity in the eastern Pacific. Basement is likely volcanics from Galapagos hotspot.

Site Summaries (continued) | Table of Contents