A 160-k.y.-old record of El Nino - Southern Oscillation in marine production and coastal runoff from Santa Barbara Basin, California, USA

A 160-k.y.-old laminated sediment record from the Santa Barbara Basin, Cali fornia, analyzed using scanning electron microscope techniques, provides a history of interannual variability of marine production and coastal runoff. We used backscatter electron imagery to measure the components of the varv e; these include a terrigenous lamina formed by seasonal runoff from winter rains together with a diatomaceous lamina that records marine production d uring the spring and early summer. Spectral analysis of terrigenous and dia tomaceous laminae thickness reveals significant periodicities of 3.1 and 8. 4 yr in the terrigenous series; these are indistinguishable, within the fre quency resolution of the spectra, from significant periodicities of 3.5 and 7.6 yr in the diatomaceous series. The 3.1 and 3.5 yr periodicities record Ei Nino modulation of coastal runoff and marine production; the 8.4 and 7. 6 yr periodicities are consistent with modulation by strong to very strong Ei Nino events. This is supported by the results of cross-spectral analysis of the terrigenous and diatomaceous records, which reveal inverse or antip hase relationships at 3.5 and 7.6 yr. Our work adds to a body of evidence t hat suggests that El Niiio has been a persistent feature of late Quaternary climate variability.