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Section 130-807C-54R-3

Location

Ontong Java Plateau

Leg Objectives

Leg 130 was chosen to provide a depth transect of carbonate deposition in the western equatorial Pacific. Our intend was to recover a complete record of Neogene, Paleogene and Late Cretaceous ocean history along this transect, with the goal of achieving a detailed reconstruction of paleoceanography and paleoclimate in a well-constrained time frame.

Site 807 water depth

2806 m

Site 807 Objectives

• Provide Paleogene and Cretaceous sediments for studies of pre-Neogene paleoceanography;
• Obtain basement rock for the studies of the origin of Ontong Java Plateau;
• Provide a second shallow-water site, off the equator, for comparison with sites 803 and 806 on the Neogene equatorial depth transect.

Lithology

Limestone with variable amount of silica cement. The sediment is moderately to highly bioturbated with mm to cm scale subhorizontal, compacted burrows. Dark reddish gray chert is present as fragments of continuous layers up to 6 cm thick and as irregularly shaped masses in limestone pieces. Limestone with volcanic ash is present at 3, 27, and 134cm (K/T boundary).

Age

Upper Maastrichtian/Lower Paleocene. Biostratigraphic data place the K/T boundary at the volcanic ash layer at 134 cm.

Discussion

The upper 100 meters of Subunit IIB is composed of  bioturbated limestone, which probably originated as pelagic carbanate sediment with isolated interbeds of mass-flow deposited material.