End-member modeling of the grain-size record of Sikouzi fine sediments in Ningxia (China) and implications for temperature control of Neogene evolution of East Asian winter monsoon

Abstract

The Late Cenozoic East Asian winter monsoon (EAWM) enhancement has been attributed to several factors, such as uplift of the Tibetan Plateau, retreat of the Paratethys Sea, and global cooling related to polar ice volume increment. However, the fundamental forcing factors remain enigmatic due to the absence of long and continuous climate records and sensitive indicators. Here we reanalyzed the published grain-size record of Sikouzi fine sediments in the western Chinese Loess Plateau through end-member (EM) modeling. The results indicate that EM 2 with grain-size peaks between 10–100 μm decreased in content from 20.1 to 17 Ma and stepwise increased from 17 to 0.07 Ma during the following six stages (17–15 Ma, 15–12 Ma, 12–8 Ma, 8–6 Ma, 6–4 Ma and 4–0 Ma). Such varying trends can be successively correlated in seven stages with the integrated benthic δ18O record, implying that global warming weakened the EAWM from 20.1 to 17 Ma and global cooling has stepwise strengthened the EAWM since 17 Ma. Therefore, we conclude that global temperature change played a major role on the evolution of EAWM during the Neogene period. By contrast, Late Cenozoic palaeogeographic reorganization caused by uplift of the Tibetan Plateau and retreat of the Paratethys Sea contributed less to the evolutionary evolution of EAWM. Spectral analysis of the EM 2 data first provided direct evidence of orbitally influenced deposition in the study area and thus the EAWM variations during the Neogene period. The 100-kyr period became weak since ~10 Ma, possibly due to the decrease in sensitivity of a more stable, continental-scale ice sheet in Antarctica to local insolation forcing, deserving further investigation.

A continuous 13.3-ka record of seismogenic dust events in lacustrine sediments in the eastern Tibetan Plateau

“…Similar analysis conducted on the Diaolin lacustrine sediments also confirmed their origin of dust deposition 23 . Analyses of grain size, REE, major and/or trace elements are commonly used to evidence the windblown origin of the Late Cenozoic sediments in East Asia 24 – 26 . Recently, conventional X-ray fluorescence (XRF) and scanning XRF elemental analysis revealed a high correlation of major and trace element abundances between Xinmocun lacustrine samples and loess-soil samples from the Chinese Loess Plateau, thereby supporting the windblown origin of the Xinmocun lacustrine sediments 10 .…”

Climate change and tectonic implications during the Pliocene climate transition interval from lacustrine records in western Wei River Basin, central China

“…Among them, CEM1 and CEM3 are positively skewed with sharp peak, CEM2 is positively skewed with gentle peak, whereas CEM4 is a single gentle peak and close to normal distribution. Therefore, changes of CEM4 in profile may reflect background dust accumulation carried by the westerlies (Jiang et al, 2017;Vandenberghe, 2013), whereas CEM1, CEM2, and CEM3 can be used as indicators of Asian winter monsoon intensity (Jiang et al, 2017;Vandenberghe et al, 2014;Vandenberghe et al, 2018) and its change in the section representing the strength of the winter wind in different periods. varied from 9.6 to 122.8 × 10 8 m 3 /kg with an average of 53.4 × 10 −8 m 3 /kg (in this paper, we only refer to the low-frequency magnetic susceptibility).…”

“…A-the Magnetic susceptibility time series according to the susceptibility age model; B-the Magnetic susceptibility time series according to the grain-size age model; C-showing the benthic δ 18 O records between 3. Jiang et al, 2017;Sun et al, 2002;Zan et al, 2018), and reveal obvious difference with river sediments for absence of the coarse particle fraction (>125 μm; Figure 4), indicating that the sediments are mainly reworked aeolian deposition. The dynamics study of aeolian deposition in the Loess Plateau shows that the particle size fraction of 10-70 μm is mainly transported by Asian winter monsoon (Fan et al, 2006;Rea et al, 1998;Sun, 2004), whereas the 2-10-μm fraction is mainly suspended by high-altitude westerly wind (Derbyshire, Meng& Kemp, 1998;Ji, Chen & Lu., 1999;Jiang et al, 2014;Sun, 2002a;Sun, 2002b;Whalley, Marshall & Smith, 1982).…”

“…The endmember analysis, which uses mathematical method to disassemble particle size distribution data into different dynamic components, is a valuable and commonly used tool in geological processes and palaeoclimate/palaeoenvironment research (Dietze, et al, 2012;Jiang et al, 2017;Yu, Colman & Li. 2016).…”

Holocene climate in arid central Asia and timing of sand dunes accumulation in Balikun Basin, Northwest China

“…The grain size and amount of aeolian materials preserved in the sediments are direct proxies suitable for reconstructing the geologic history of the wind intensity and aridity of the aeolian source region (Ding et al, 202; Jiang 2014; Paterson & Heslop, 2015; Rea, 1994; Sun, 204). The fundamental consensus is that a more arid climate and intense winds will be advantageous in increasing the amount and grain size of dust (Rea, 1994), with different dynamic processes potentially yielding diagnostic GSDs and constituent components (Paterson & Heslop, 2015; Prins et al, 202; Sun, 204), and have been widely used to reconstruct past climate in monsoon‐ and westerlies‐dominated regions during the Cenozoic (Ding et al, 202; Jiang et al, 2014, 2017; Rea, 1994). Since the mixed sediments potentially obscure different original environmental signals (Prins et al, 202), an analysis of the standard deviation values and grain‐size classes has been proposed to identify the grain‐size intervals with the highest variability and environmental sensitivity (Boulay & Colin, 203).…”