8. Site 11471

Shipboard Scientific Party2

BACKGROUND AND OBJECTIVES

The objective of Site 1147 was to recover a continuous sequence of the uppermost hemipelagic sediments (75 meters below seafloor [mbsf]) near Site 1148 (SCS-5C), so that the near-surface sediments lost to slumping or channeling at Site 1148 could be recovered.

Site 1147 is located at 18°50.11ŽN, 116°33.28ŽE, at shotpoint 1940 on JOIDES Resolution seismic Line 5C-2 at a water depth of ~3245 m (Fig. F9 in the "Leg 184 Summary" chapter; see also Figs. F5, F15, F16A, F16B, and F17B, all in the "Seismic Stratigraphy" chapter). The site is ~0.45 nmi upslope from Site 1148 (the revised location of SCS-5C).

The repositioning of Site SCS-5C to shotpoint 1980 on JOIDES Resolution seismic Line 5C-2 placed the site location in the scar of a surface slump. Interpretation of the seismic records suggests that from 10 to 20 m of sediment are missing and that the disturbance to the sediment column may extend downward another 20 to 30 m. Site 1147 was proposed to recover the uppermost sediments, which are missing or disturbed at Site 1148. Correlation among multisensor track (MST) and color spectral reflectance (CSR) data at these two sites indicates a maximum of 7 m of missing section at the top of Site 1148 relative to Site 1147. A continuous, distinct, and undisturbed reflector at ~0.08 seconds below seafloor (~60 mbsf) can be easily traced between Sites 1147 and 1148.

1Examples of how to reference the whole or part of this volume can be found under "Citations" in the preliminary pages of the volume.
2Shipboard Scientific Party addresses can be found under "Shipboard Scientific Party" in the preliminary pages of the volume.

Ms 184IR-108

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