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 d 13 C 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 CO 2 during the mid-late Quaternary. Three different indices indicate that Asian dust contributes between $15% and $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 CO 2 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 CO 2 concentrations during ice ages.

ENSO‐Like Modulated Tropical Pacific Climate Changes Since 2.36 Myr and Its Implication for the Middle Pleistocene Transition

“…Our eolian EM2 (12 lm) does not agree with the grain size of the eolian dust in the North Pacific Ocean which shows a size mode that is slightly coarser than 2 mm, with little material coarser than 16 mm (Rea & Hovan, 1995). Such inconformity is due to the different mechanisms of eolian transportion: westerly dominated eolian dust in the North Pacific Ocean (Lim & Matsumoto, 2006;Rea & Hovan, 1995) and EAWM controlled eolian dust in the low-latitude Southeast Asia area (Qin et al, 1995;Wan et al, 2012;Xu et al, 2015).…”

“…For the mechanism of dust transport, backward trajectory analyses has shown that the particles transported to the Benham Rise can be traced back to the East Asian deserts (Jiang et al, 2013). Previous studies have shown that 10-50% (average 35%) of the terrigenous materials on the Benham Rise sediments is comprised of East Asian dust (Jiang et al, 2013;Xu et al, 2015), which is comparable with the proportion of EM2 (average 40%). In the South China Sea, EMA of detrital grain-size composition in ODP Sites 1146 and 1144 suggest that the intermediate end-member is primarily an eolian population with a diameter of about 9-11 lm, whereas the fine (about 2-5 lm) and coarse (about 19-25 lm) end-members are associated with fluvial inputs (Boulay et al, 2007;Wan et al, 2007).…”

“…Luzon Island and Chinese eolian dust (Jiang et al, 2013;Wan et al, 2012;Xu et al, 2015;Yu et al, 2016). For the mechanism of dust transport, backward trajectory analyses has shown that the particles transported to the Benham Rise can be traced back to the East Asian deserts (Jiang et al, 2013).…”

“…The progressive cooling of the high-latitudes in the Quaternary may be responsible for our observation here. A newly identified 100 kyr dominant period between 2.2 and 1.6 Myr in the ENSO-like modulated Pacific climate records indicates that the ENSO-like system may play a key role in facilitating or responding to the global climate changes.In this study, we present a high-resolution Pleistocene grain-size record (combined with an inversion algorithm for end-member modeling of grain-size compositional data) of detrital sediments from core MD06-3050 collected on the Benham Rise (Figure 1) spanning the last 2.36 Myr in order to: (i) constrain the sources Key Points: First high-resolution grain-size record in the West Philippine Sea over the past 2.36 Ma High-latitudes cooling drove the Equatorial Pacific SST contrast and contributed to the tropical climate changes A 100 kyr dominant period between 2.2 and 1.6 Myr was revealed in the ENSO-like influenced records Supporting Information: Supporting Information S1 Data Set S1 PUBLICATIONS of different grain-size end-members and reconstruct its long-term changes; (ii) compare the monsoon records of the Southeast Asia (the West Philippine Sea and the South China Sea) and the equatorial East Pacific (EEP) climate changes (upwelling and SST records) in order to establish a link between long-term climate changes in the tropical Pacific; and (iii) explore the possible influence of internal feedback mechanisms on the tropical climate changes.The sedimentary deposits on the Benham Rise mainly result from a complex mixture of changing percentage in sedimentary sources (eolian or fluvial supply) (Jiang et al, 2013;Wan et al, 2012;Xu et al, 2015;Yu et al, 2016), while the influences of sea-level changes and modification of the land-sea configuration are negligible. This is because the Luzon volcanic arc block the suspended materials from the East Asian Rivers (Figure 1) and the continental shelf in the west Luzon Island is very narrow and deep (average less than 10 km, the core MD06-3050 is about 230 km from the shelf with a water depth 2,967 m).…”

“…The sedimentary deposits on the Benham Rise mainly result from a complex mixture of changing percentage in sedimentary sources (eolian or fluvial supply) (Jiang et al, 2013;Wan et al, 2012;Xu et al, 2015;Yu et al, 2016), while the influences of sea-level changes and modification of the land-sea configuration are negligible. This is because the Luzon volcanic arc block the suspended materials from the East Asian Rivers (Figure 1) and the continental shelf in the west Luzon Island is very narrow and deep (average less than 10 km, the core MD06-3050 is about 230 km from the shelf with a water depth 2,967 m).…”