171B Scientific Prospectus

Site: BN-4Alt

Priority: 1

Position: 29°59.538'N, 76°31.416'W

Water depth: 1652 m

Sediment thickness: >3000 m

Seismic coverage: Gloria Farnella 1987 SCS Line 19, TD5UW (shotpoint 1461) (see seismic profile).

Objectives: Determine history of Paleogene and Cretaceous water chemistry, carbonate productivity, and deep-water and surface temperature as well as evolutionary history of pelagic microfossils. Core Paleocene-Eocene and Cretaceous-Paleogene boundaries for paleoceanographic, evolutionary, and stratigraphic studies. Shallow-intermediate point on depth transect.

Drilling program: 1. APC coring to 160 mbsf or refusal (oriented): Hole A.
2. Holes B and C cored to 160 mbsf or refusal by unoriented APC.
3. Hole A deepened by XCB to 500 mbsf.

Logging and downhole operations: Standard strings (triple-combo geophysical and FMS) and GHMT (magnetic susceptibility). Adara and WSTP temperature measurements may be run if time permits. Core orientation on at least the A hole.

Nature of rock anticipated: Nannofossil-foraminifer ooze, chalk, cherty limestone, calcareous clay.

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