Contribution of Asian dust and volcanic material to the western Philippine Sea over the last 220 kyr as inferred from grain size and Sr‐Nd isotopes

Abstract

Asian dust and volcanogenic materials are two major components in the northwestern Pacific. Quantitatively distinguishing them and estimating their mass accumulation rates (MARs) are very important for understanding regional and global climate change. Here we present the grain‐size composition of detrital sediments and the radiogenic strontium (Sr) and neodymium (Nd) isotopic compositions of different grain‐size fractions of detrital sediments that were recovered from the western Philippine Sea. These new records show that the different grain‐size distributions can be associated with 1) Asian dust from the western and central Chinese deserts and Chinese loess and 2) volcanogenic materials that were derived from the Luzon Islands. The MARs of this Asian dust and volcanic materials are obtained by using Weibull‐function fitting. The MARs of Asian dust and volcanic materials are coupled with the glacial‐interglacial cycle; these values are found to have been higher and more variable during the glacial period than during the interglacial period. We argue that the strengthening aridity of the Asian continent, which is connected to solar insolation and ice volume variations from orbital eccentricity, constitutes an important mechanism that drives the high MARs of glacial dust in the western Philippine Sea. The internal positive feedback of dust may be another important mechanism. The significant increase in volcanic material during the glacial period was caused by sea level changes, which were driven by the ice volume and solar insolation at high latitudes, and by strengthened precipitation from the El Niño/Southern Oscillation (ENSO), which is driven by orbital eccentricity and precession cycles on the Luzon Islands.

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

“…However, we cannot entirely exclude other possibilities. Our result seems inconsistent with the Sr-Nd isotopic and grain-size records from a nearby core Ph05-5, which reveal that the Asian dust contribute more in fine particles (<5 lm) than the moderate coarse ones (from 5 to 20 lm) (Jiang et al, 2016). Such conflict observation might be due to different local circulation and/or difference in grain-size end-member definition and Sr-Nd isotopic ranges.…”

“…In addition, nine volcanic ash layers in core MD06-3050 (Figure 3), which show parallel ages compared to the well constrained volcanic ash layers from core MD97-2143 (Ku et al, 2009), correspond to peaks of high proportions (more than 50%) of EM3 ( Figure 3). Our result seems inconsistent with the Sr-Nd isotopic and grain-size records from a nearby core Ph05-5, which reveal that the Asian dust contribute more in fine particles (<5 lm) than the moderate coarse ones (from 5 to 20 lm) (Jiang et al, 2016). The coarse material, larger than 25 lm, cannot be easily transported from Taiwanese rivers by surface current to the Benham Rise.…”

Seasonal Variations in the Siliciclastic Fluxes to the Western Philippine Sea and Their Impacts on Seawater εNd Values Inferred From 1 Year of In Situ Observations Above Benham Rise

“…Maps showing the locations of the sediment trap site T1 (solid circle in a); the seawater sites GeoB17005 (Behrens et al, ) in addition to St1, St2, and St3 (solid pluses in b; Wu et al, ) and 14 and 28 (solid pluses in a; Jeandel et al, ); the fossil fish teeth/debris sites NB29 and NB20 (hollow pluses in a; Horikawa et al, ); the foraminifer sites RC17–177, RC17–178, V28–255, and V28–294 (solid circles in a; Hu et al, ); the sediment cores MD06–3047 (Xu et al, ), Deep Sea Drilling Project (DSDP) site 292 (Hickey‐Vargas, ), MD06–3050 (Yu et al, ), Ph05–5 (Jiang et al, ), PC631 (hollow circles in b; Seo et al, ), and RP2OC72‐01GC (hollow circle in a; Pettke et al, ); the weather stations Palanan and Vinzons (hollow squares in b) in the Philippine Sea and nearby regions. The rectangle part of (a) is enlarged in (b).…”

“…However, the influences of monsoon on rainfall and sediment transport to the Benham Rise remain speculative at present and need to be further explored. Therefore, only a detailed study of the processes by which siliciclastic inputs were delivered to the western Philippine Sea in 2015 permits us to test the hypothesis of a potential link between precipitation over volcanic islands and siliciclastic inputs to the deep sea, as suggested by previous research on Quaternary sediments from the Benham Rise (Jiang et al, ; Yu et al, ).…”

Elemental and Sr‐Nd Isotope Geochemistry of Sinking Particles in the Northern South China Sea: Implications for Provenance and Transportation

“…Although Nd isotopes of sinking particles have rarely been analyzed, Nd isotopes have served as reliable tracers of provenance analysis because their compositions are stable during diagenesis and transport (Goldstein et al, 1984;Goldstein & Jacobsen, 1988;Li et al, 2003;Shao et al, 2009). Associated with Nd isotopes, Sr isotopes are also useful in tracing the provenance of marine sediments (Goldstein & Hemming, 2003;Jiang et al, 2016;Wei et al, 2012). Therefore, the Sr-Nd isotope characteristics of sinking particles may also be effective signals in provenance analysis.…”