Radiolarian responses to the 1957-1958 and 1964 El Ninos and 1963 anti-El Nino and a search for similar events in the fossil record
Casey, Richard E.
Master of Arts
Radiolarian distributions and physical oceanographic data from the southern California borderlands indicate the following: Strong anti-El Nino periods can be characterized by 1) average radiolarian standing crop, 2) high percentage of transition-central radiolarian fauna, and 3) low percentage and number of warm water radiolarian fauna. This distribution pattern is attributed to strong wind-driven upwelling and reduced northward transport by the California Countercurrent during anti-El Nino periods. Strong El Nino periods were typically 1) high in radiolarian standing crop, 2) low percentage and high number of cold water fauna, and 3) high percentage and number of warm water fauna. This distribution is attributed to reduced wind-driven upwelling, enhanced northward countercurrent transport, and geostrophic doming of the cold water masses in the shear zone between the California Current and California Countercurrent. Preliminary work on a varved sample from the Monterey Formation, Lompoc, California indicates that variations of radiolarian populations appear to represent changes in oceanic circulation similar to those recorded in the Santa Barbara Basin varved sediments.