Research ArticleGEOLOGY

Critical transitions in Chinese dunes during the past 12,000 years

See allHide authors and affiliations

Science Advances  26 Feb 2020:
Vol. 6, no. 9, eaay8020
DOI: 10.1126/sciadv.aay8020
  • Fig. 1 Coexisting active and stabilized dunes in northern China at the present and in the geological past.

    (A) Geographic location of dune fields in northern China marked by the dashed box. (B) Locations of the Mu Us, Otindag, and Horqin dune fields. Precipitation in these dune fields is dominated by the Asian summer monsoon from the southeast, and strong wind predominantly comes from the northwest by the East Asian winter monsoon (EAWM). The triangles represent the studied dune stratigraphic sections. 1, SGD (Shigadu); 2, TK (Tuke); 3, JJ (Jinjie); 4, ZBT (Zhenbeitai); 5, Dali Lake; 6, Gonghai Lake. Markers 7 and 8 indicate the locations for (C) and (D). (C and D) Examples of active and stabilized dunes coexisting in the Mu Us and Horqin dune field, respectively. High reflectance indicates bare sand dunes, while dark color reflects dense vegetation patches where the dunes are stabilized. North is toward the top of the satellite images from Google Earth. (E to G) Time slices showing the spatial distribution pattern of dune activity at individual sites during 8 to 7, 6 to 5.5, and 2 to 1.5 ka ago, respectively. The brown/yellow symbols indicate stabilized/active state of the dunes. Rainfall data in (A) are based on modern observations, while precipitation in (E to G) is simulated by the Earth system model MPI-ESM. See fig. S2 for other time intervals since 12 ka ago, and data file S3 for sites recording sand deposition or soil development during each interval.

  • Fig. 2 Critical transitions in dune activity at individual sites in response to monsoon precipitation change.

    (A) Temporal pattern of the shifts in dune activity at individual sites revealed by a cluster of study sites from the Mu Us dune field as an example. The temporal phases of active dune state (indicated by aeolian sand deposit) and stabilized dune state (indicated by the paleosol) are illustrated by yellow and brown columns (or bars), respectively. The name of the section at each site is labeled on the left of each column or on the bar. The short bar refers to discontinuous site, while the long column is based on the accumulative site. (B) Changes in dune activity at four representative accumulative sites (SGD, TK, ZBT, and JJ) in the Mu Us dune field indicated by magnetic susceptibility of the sediments. Changes in monsoon precipitation (gray line) are reconstructed on the basis of the Gonghai Lake pollen record (21). The magnetic susceptibility data were normalized to the standard Z score: Z = (XV)/SD; here, X is the original value, and V and SD are the averaged value and standard deviation of the time series. High/low values of the normalized Z score represent high/low magnetic susceptibility, indicating the shifts between active and stabilized dune states. The green/red arrow indicates the transition from active/stabilized to stabilized/active state, with different timing at each site. Note the asymmetry between the stabilization and activation processes (further discussed in the main text). The column shows the frequency distribution of the normalized Z score of magnetic susceptibility. Modern annual precipitation (MAP) and sedimentation rate (SR) at each site are labeled in the figure. The MAP at the Gonghai Lake is ~445 mm, approximate to that of the southeast margin of the dune fields. ZBT data were previously published by Lu et al. (20). The original data for the JJ site was from Ma et al. (59).

  • Fig. 3 Critical transitions of the entire Chinese dune fields to Holocene climate change.

    (A) Percentage of stabilized dune sites relative to all sites sampled in the dune fields over the past 12,000 years and annual precipitation in northern China over the same time period using the pollen-based reconstruction from Gonghai Lake (21). Error bars for percent stable represent 95% confidence interval based on 10,000 simulations incorporating errors of numerical ages. (B) Simulated precipitation change from the (a) MPI-ESM model and (b) CCSM3 model and boreal summer irradiation (60). (C) Index of the EAWM from a diatom record (46) and a marine record (45). The higher AG/CS (A. granulate and C. stelligera) represents stronger winter monsoon. The thermal gradient in the northern South China Sea represented by ΔT is strongly modulated by the EAWM, and the lower ΔT indicates stronger monsoon (45). (D) Plot of percent stabilized dune sites, relative to all the dune field sites sampled, against precipitation variation; note the hysteresis behavior. Precipitation data in (D) were based on the Gonghai Lake reconstruction. Notice that MAP at the Gonghai Lake is similar to the southeast margin of the dune fields but is about 150 mm higher than the average precipitation of the dune fields. Thus, the wide range of reconstructed precipitation (300 to 600 mm) refers in particular to the estimated annual precipitation at the southeast margin of the dune fields.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/9/eaay8020/DC1

    Fig. S1. Typical dune stratigraphic sections at individual sites from the dune fields of northern China.

    Fig. S2. Coexisting active and stabilized dunes in northern China during the past 12,000 years.

    Data file S1. List of study sites from the dune fields of northern China.

    Data file S2. Dataset of dune chronologies in the dune fields of northern China.

    Data file S3. The sites where sand deposition or soil development is recorded during each time interval of the past 12,000 years.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Typical dune stratigraphic sections at individual sites from the dune fields of northern China.
    • Fig. S2. Coexisting active and stabilized dunes in northern China during the past 12,000 years.
    • Legends for data files S1 to S3

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Data file S1 (Microsoft Excel format). List of study sites from the dune fields of northern China.
    • Data file S2 (Microsoft Excel format). Dataset of dune chronologies in the dune fields of northern China.
    • Data file S3 (Microsoft Excel format). The sites where sand deposition or soil development is recorded during each time interval of the past 12,000 years.

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article