Pelagic clay of the east-central Pacific province is shown to be a mixture of three primary detrital components, reflecting continental source areas in Asia, North America, and Central and South America. Relative contributions from each source area are a function of geography, and this distribution appears to have remained constant over the past five million years, despite changing flux rates. A Q-mode factor analysis of downcore records for Pb, Sr, and Nd isotopes identified three factors that account for 98% of the total variance. These factors represent the radiogenic isotopic signatures of 1) late Cenozoic Asian dust, which dominates in the central North Pacific; 2) North American continental hemipelagic/eolian sources, restricted mainly to the easternmost North Pacific at ~30 °N latitude; and 3) Central and South American sources, restricted to areas east of ~100 °W longitude. South of the Intertropical Convergence Zone (~6 °N), the Asian dust signature diminishes abruptly. We conclude that late Cenozoic Asian dust sources can be isotopically differentiated downcore from both North American and South and Central American sources in the eastcentral Pacific. This approach has a utility for identifying changes in long-term Cenozoic atmospheric circulation patterns.

Ages reffered to the time scale of Berggren et al. (1995). Analysed sediment is a detrital extract <38 µm. The time integrated 238U/204Pb ratio of the source is referred to as my and kappa is the time-integrated 232Th/238U of the source, calculated from the Pb isotopic ratios. These parameters were calculated using the single stage Holmes-Houtermans model, and the initial bulk earth Pb isotopic values of Tatsumoto (Faure, 1986)

Supplement to: Stancin, Andrea M; Gleason, James D; Rea, David K; Owen, Robert M; Moore, Theodore C; Blum, Joel D; Hovan, Steven A (2006): Radiogenic isotopic mapping of late Cenozoic eolian and hemipelagic sediment distribution in the east-central Pacific. Earth and Planetary Science Letters, 248(3-4), 840-850