Geochemically Defined Mean Position of the Intertropical Convergence Zone in the Central Pacific

Abstract

The Intertropical Convergence Zone (ITCZ) is a band of vigorous convection and high precipitation formed by the confluence of southeasterly and northeasterly trade winds, and acts as a barrier to cross-equatorial dust transport. We investigate the provenance of dust in the surface sediments of 16 cores collected along a 131.5 degrees W transect from the equator to 16 degrees N in the central Pacific. The results reveal well-defined Asian dust signals north of 7 degrees N and mixed Asian-South American source signals south of 6 degrees N. We propose the southernmost latitude with an intact Asian source signal (7 degrees N) as the present-day mean ITCZ position in terms of dust provenance in the central Pacific. This geochemically defined mean ITCZ position reflects differences in thermal and dust fluxes between hemispheres and can be used as a reference for quantitatively assessing ITCZ displacement in the sedimentary down-core records back to ca. 14 Ma.