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GCR Display Cores

Section 136-842B-4H-1

Location

Hawaiian Arch, approximately 225-km south-southwest of the island of Oahu.

Site objectives

To install a reentry cone on the seafloor and the casing of a hole to basement for use as a test site for the Ocean Seismic Network.

Lithology

Dark reddish brown clay and zeolitic clay. In general, the clay is homogeneous, structureless, and highly disturbed by drilling. Faint, wavy, subparallel, laminations are present at 86-95 cm.

Age

Upper Eocene–Middle Miocene

Discussion

The limited depth of sampling precludes an in-depth interpretation of the diagenetic processes taking place in the red clay sediments of site 842. Nonetheless, there is evidence of a limited extent of bacterially mediated oxidation of organic matter in the SO4, NH4, and PO4 pore-water profiles. Silica diagenesis, on the other hand, is well documented by the dissolved silica profile.