Contribution of aeolian dust in Japan Sea sediments estimated from ESR signal intensity and crystallinity of quartz

Abstract

[1] Late Quaternary hemipelagic sediments in the Japan Sea contain aeolian dust from East Asia which potentially records past variations in the Asian monsoon and the westerly jet. However, extracting information about aeolian dust from Japan Sea sediments is difficult because the sediments also contain detrital material from the Japanese Islands. Here we present a method for extracting the aeolian dust components from Japan Sea hemipelagic sediments using provenance analysis of different size fractions. Hemipelagic sediments of the Japan Sea can be described by a combination of two populations characterized by lognormal grain size distributions with different median grain sizes, which are called the coarser (2-15 mm) and the finer (<10 mm) populations. We characterized these populations on the basis of provenance analyses, using the electron spin resonance (ESR) signal intensity and crystallinity of quartz. The results suggest that quartz in the coarser population has been mostly supplied from Northern China and Siberia/northeastern China by aeolian transport, whereas quartz in the finer population has been dominantly supplied by rivers draining the Japanese Islands.

The Grain Size Influence on the E1' Centre Observed in Quartz of Atmospheric Deposition at Two Japanese Cities: A Preliminary Study

“…This would indicate that the main part of the precipitated atmospheric dust was brought by Kosa, having higher oxygen vacancy values from inland China. The number of oxygen vacancies in finer fraction, ranging up to 8.5 units is consistent with the values observed by Toyoda and Naruse (2002), for MIS 1 or in southern Japan and in inland China for MIS 2, which is 6-8 units, and that of Taklamakan component reported by Nagashima et al (2007), which is 8.8 units. This is also confirmed by our observation of the local river sediments in the present study.…”

“…2a and 2b are not so simple. The numbers of oxygen vacancies in finer two fractions for April 1969 are 6.0-8.5 units both at Fukuoka and Akita, being consistent with the values for Taklamakan (Nagashima et al, 2007) while the values are lower in 1971 at both cities and in Feb. 1969 at Akita. We could still adhere to the idea that finer fractions are aeolian dust from China, to explain these lower values.…”

“…2a for Fukuoka and 2b for Akita as a function of grain size. The numbers of the oxygen vacancies are described in a unit of 1.3×10 15 spins/g as was done in previous studies (Toyoda and Naruse, 2002;Nagashima et al, 2007). It is a common feature that smaller grain size fractions show higher number of oxygen vacancies although there are month to month and year to year variations in the average level.…”

“…These values are systematically larger in northern Japan, implying a contribution of aeolian dust from sources originating from older basement rocks. Nagashima et al (2007) investigated the sources of the aeolian dust accumulated in the sediment of the Sea of Japan using the number of oxygen vacancies in quartz together with another proxy -crystallinity index of quartz. A correlation between the dust contribution from Taklamakan desert and the summer insolation index at 30ºN was found.…”

Investigation of the temporal change of the sources of Aeolian dust delivered to East Asia using electron spin resonance signals in quartz

“…They argued that there was significant contribution of dust to northern Japan in MIS 2 from a source with ages older than the source which contributes to Chinese loess plateau, most probably those from north eastern Siberia where basement rocks are Precambrian. Nagashima et al (2007) further investigated the dust contributions to sediments in core samples taken in Sea of Japan using the E 1 ' center signal intensities (number of oxygen vacancies) and crystallinity indexes of quartz, based on the difference in those values, where the number of oxygen vacancies ranges from 4.5 to 9.6 for fine grain sediments in Taklimakan desert and from 12.3 to 16.6 for Mongolian Gobi desert . They found that the contribution from Taklimakan desert had been higher in warmer period and that from Mongolian Gobi desert in colder period during the last 150 ka.…”