Terrigenous deposition, either fluvial or aeolian, is altered by latitudinal shifts in the Intertropical Convergence Zone (ITCZ). For example, a southern shift in the ITCZ during the Northern Hemisphere winter coincides with higher aeolian inputs in response to strong easterly trade winds, whereas during the northern migration of the ITCZ in the summer, higher fluvial inputs are observed. A scientist from Boston University will carry out a geochemical study of samples recovered from a sediment trap array in the Cariaco Basin to characterize seasonal changes in the chemical composition and total flux of the terrigenous component. Material recovered in the traps over a five year period will be analyzed for major, trace and rare earth elements, as well as radiogenic isotopes. Changes in chemical composition and total flux will be assessed as a function of precipitation, wind stress, and upwelling to understand how modern processes control the terrigenous variability at the site. In addition, this PI will complement the water column work by collecting samples along the Venezuelan coastal shelf, local rivers, Aeolian samples from Barbados, and material derived from the Orinoco River to constrain possible end-member sources.
In terms of broader impacts, results from this study will further our understanding of how changes in the ITCZ alters inputs of terrigenous material which in turn can provide information on global climate variations in tropical latitudes. The project utilizes samples collected as part of the CARIACO time series off the coast of Venezuela and is a collaborative effort between Venezuelan and U.S. scientist. A graduate student from Venezuela will be trained and supported as part of this study.
