A semiannual radiocarbon record of a modern coral from the Solomon Islands

Abstract

Radiocarbon records from modern corals have long been recognized for their usefulness as a geochemical tracer of surface ocean waters and oceanic upwelling. Pacific corals are especially interesting because of their potential relevance to El Niño – Southern Oscillation (ENSO) events. At present, the Pacific Ocean is undersampled with respect to radiocarbon time series. This study establishes a 14C time series for a coral from the Solomon Islands, located near the center of the Western Pacific Warm Pool (WPWP). We present radiocarbon results from a Porites colony which grew in Marau Sound, on the east coast of Guadalcanal. A semiannual record of 14C was constructed from measurements of alternating bands which grew continuously from 1944 to 1994. The record reflects the uptake of atmospheric bomb-produced 14C since the late 1950s with superimposed subannual radiocarbon variations, presumably related to changes in ocean circulation. Although the coral radiocarbon is influenced by ENSO events, the record is not closely correlated with the Southern Oscillation Index (SOI) for the same period.