Quantitative estimates of Asian dust input to the western Philippine Sea in the mid-late Quaternary and its potential significance for paleoenvironment

Abstract

We present a new high-resolution multiproxy data set of Sr-Nd isotopes, rare earth element, soluble iron, and total organic carbon data from International Marine Global Change Study Core MD06-3047 located in the western Philippine Sea. We integrate our new data with published clay mineralogy, rare earth element chemistry, thermocline depth, and delta C-13 differences between benthic and planktonic foraminifera, in order to quantitatively constrain Asian dust input to the basin. We explore the relationship between Philippine Sea and high-latitude Pacific eolian fluxes, as well as its significance for marine productivity and atmospheric CO2 during the mid-late Quaternary. Three different indices indicate that Asian dust contributes between similar to 15% and similar to 50% to the detrital fraction of the sediments. Eolian dust flux in Core MD06-3047 is similar to that in the polar southern Pacific sediment. Coherent changes for most dust flux maximum/minimum indicate that dust generation in interhemispheric source areas might have a common response to climatic variation over the mid-late Quaternary. Furthermore, we note relatively good coherence between Asian dust input, soluble iron concentration, local marine productivity, and even global atmospheric CO2 concentration over the entire study interval. This suggests that dust-borne iron fertilization of marine phytoplankton might have been a periodic process operating at glacial/interglacial time scales over the past 700 ka. We suggest that strengthening of the biological pump in the Philippine Sea, and elsewhere in the tropical western Pacific during the mid-late Quaternary glacial periods may contribute to the lowering of atmospheric CO2 concentrations during ice ages.