Upper cretaceous (Senonian) bathyal pelagic sediments withGlobotruncanafrom the Solomon Islands

Abstract

Extremely fine‐grained pelagic oozes overlie basal basaltic lavas on Malaita Island, on the Pacific flank of the Solomon Islands group. These sediments contain up to 20% planktonic (but not benthonic) Foraminifera, but have less than 5% acid‐insoluble clay and little or no terrigenous material. They are associated with radiolarian chert and with finely disseminated marine manganese. The Foraminifera include several species of Globotruncana, referred to G. arca, G. havanensis, G. lapparenti and G. tricarinata. The sediments accumulated in a low‐energy, deep‐water environment (exceeding 1,000 m.) during Late Cretaceous (Senonian) time, probably in the late Senonian. These sediments are the oldest in the Solomon group and older than any so far found in the outer part of the Melanesian re‐entrant. Their age supports the idea that the Solomon Islands began their geological history in the Cretaceous.