Does Eolian Flux to the Northwest Pacific Ocean Reflect Persistent Asian Interior Aridity on Orbital Timescales?

Abstract

Northwest Pacific sedimentary eolian dust flux records have long been used to make direct inferences about Asian interior aridity. However, factors other than aridity can impact dust production rate. We present here an integrated environmental magnetic, electron microscopic, sedimentologic, and geochemical investigation of eolian dust records from Northwest Pacific Ocean Drilling Program Hole 1207A between 1.0 and 1.5 Ma. Reconstructed fluxes of bulk eolian dust and illite, the predominant clay mineral (>72% proportion), are both higher and lower during glacials and interglacials, respectively. Lower illite chemical index values reflect stronger physical weathering during glacials. We attribute eolian flux peaks to increased availability of wind-erodible particles caused by enhanced physical weathering in dust source areas due to strengthened Asian interior glacial activity in response to glacial cooling. This evidence demonstrates that Northwest Pacific eolian flux does not only reflect persistent Asian interior aridity on orbital timescales.