Youbin Sun,1 Ryuji Tada,2 Jun Chen,3 Qingsong Liu,4 Shin Toyoda,5 Atsushi Tani,6. Junfeng Ji,3 ... However, debate still exists on which deserts in east Asia.
GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L01804, doi:10.1029/2007GL031672, 2008
Tracing the provenance of fine-grained dust deposited on the central Chinese Loess Plateau Youbin Sun,1 Ryuji Tada,2 Jun Chen,3 Qingsong Liu,4 Shin Toyoda,5 Atsushi Tani,6 Junfeng Ji,3 and Yuko Isozaki2 Received 27 August 2007; revised 18 October 2007; accepted 30 November 2007; published 5 January 2008.
[1] Eolian dust deposits in north China provide an excellent means of determining past variations in continental paleoclimate and atmospheric circulation. However, debate still exists on which deserts in east Asia are the dominant sources of Chinese loess and whether the dust provenance has shifted significantly at different time scales. Here we present new constraints on the provenance of fine-grained dust deposited on the central Chinese Loess Plateau (CLP) by combining electron spin resonance signal intensity and crystallinity index of fine-grained quartz contained in samples from two loess-paleosol sequences. Our results show that the fine-grained dust deposits on the CLP originate mainly from the Gobi desert in southern Mongolia and the sandy deserts in northern China (primarily the Badain Juran and Tengger deserts), rather than from the Taklimakan desert in western China, at least during the last climatic cycle. The dominant source of finegrained dust varied significantly, from southern Mongolia during cold periods, to northern China during warm periods. The glacial-interglacial provenance fluctuations are strongly coupled with changes in the intensity of the near-surface northwesterly winter monsoon. Citation: Sun, Y., R. Tada, J. Chen, Q. Liu, S. Toyoda, A. Tani, J. Ji, and Y. Isozaki (2008), Tracing the provenance of fine-grained dust deposited on the central Chinese Loess Plateau, Geophys. Res. Lett., 35, L01804, doi:10.1029/2007GL031672.
1. Introduction [2] The wind-blown loess deposits in north China encode past changes in east Asian monsoons and Asian inland desertification [An, 2000; Guo et al., 2002], which have been further linked to the stepwise uplift of the HimalayaTibetan Plateau as well as orbitally driven changes in solar radiation and global ice volume [An et al., 1991, 2001; Ding et al., 1995]. Previous reconstructions of the east Asian monsoons were based mainly on an assumption that the loess-paleosol deposits on the Chinese Loess Plateau (CLP) 1 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, China. 2 Department of Earth and Planetary Science, University of Tokyo, Tokyo, Japan. 3 Department of Earth Sciences, Nanjing University, Nangjing, China. 4 National Oceanography Centre, University of Southampton, Southampton, UK. 5 Department of Applied Physics, Okayama University of Science, Okayama, Japan. 6 Department of Earth and Space Sciences, Osaka University, Osaka, Japan.
Copyright 2008 by the American Geophysical Union. 0094-8276/08/2007GL031672
are derived from a homogeneous dust source in inland Asia [e.g., Liu et al., 1994; Gallet et al., 1996; Jahn et al., 2001]. While an array of mineralogical, chemical, and isotopic tracers has aided in distinguishing various source regions [Zhang et al., 1997; Derbyshire et al., 1998; Jahn et al., 2001; Sun, 2002; Chen et al., 2007], the relative importance of these sources is still controversial. Extant provenance studies have yielded differing viewpoints on whether the dust provenance has experienced significant shifts [Zhang et al., 1997; Sun, 2005] or is more uniform during the late Cenozoic [Gallet et al., 1996; Jahn et al., 2001; Wang et al., 2007]. [3] To better determine the dominant sources of Chinese loess, we employed a newly developed provenance-tracing approach by using a combination of Electron Spin Resonance signal intensity of the E10 center of quartz (hereafter referred to as ESR signal intensity) and Crystallinity Index of quartz (hereafter referred to as CI) [Sun et al., 2007]. ESR signal intensity is proportional to the age of quartz with higher values from older host rocks [e.g., Toyoda and Naruse, 2002]. The CI reflects temperature and crystallization rates during formation and depends on the types of source rocks [Murata and Norman, 1976]. These two parameters have been employed successfully as provenance tracers to differentiate the major Gobi and sandy deserts in east Asia [Sun et al., 2007], and to trace the sources of eolian dust components in the Japan Sea sediments [Nagashima et al., 2007]. [4] Here we report the ESR signal intensity and CI of fine-grained quartz (
