Research ArticleENVIRONMENTAL SCIENCE

Australian shelf sediments reveal shifts in Miocene Southern Hemisphere westerlies

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Science Advances  10 May 2017:
Vol. 3, no. 5, e1602567
DOI: 10.1126/sciadv.1602567
  • Fig. 1 Map of Australia and Southeast Asia showing site locations and prevailing atmospheric circulation features.

    Red dots indicate the study sites (IODP Sites U1459 and U1464) and sites used for interpretation from the South China Sea (ODP Site 1146) (4, 28) and off Tasmania (ODP Site 1171) (5). Major weather features and prevailing wind directions are indicated, including ITCZ, the westerlies, and the Subantarctic Front (SAF).

  • Fig. 2 Schematic meridional profiles showing relative movement of atmospheric circulation patterns.

    Meridional cross section from the South China Sea to Antarctica as shown in Fig. 1. The location of Australia and the drill sites are indicated at their respective paleolatitudes. Relative movement of the major climatic systems related to the Hadley circulation and oceanographic features such as the ITCZ, subtropical highs, westerlies, and Subantarctic Front (SAF) is shown for three time periods: (A) Modern; (B) Late Miocene (~8 Ma); and (C) Middle Miocene (~15 Ma). Cloud and sun symbols indicate wetter or drier conditions, respectively.

  • Fig. 3 Proxy data depicting 10 million year history of Middle to Late Miocene climate change in Western Australia.

    (A) Wireline log data of Th/K (green) and K (%; blue) from IODP Site U1464 (18°03.9′S, 118°37.8′E, 264-m water depth). (B) Wireline log data of Th/K (green) and K (%; blue) from IODP Site U1459 (28°40.2′S, 113°33.5′E, 192-m water depth). Black curves are 15-point running averages. Vertical dashed lines indicate the limits for either arid or humid intervals (see supplementary text). Vertical blue bars summarize periods of dominantly dry, intermediate, or wet conditions. Gray bar indicates the time interval of major AIS expansion.

  • Fig. 4 Comparison of changes in southwest Australian precipitation with global climate.

    (A) Average siliciclastic input (black) as reflected by wireline log data of K (%) from IODP Site U1459 (15-point running average). Shading highlights dry (orange) versus wet (blue) conditions. (B) Relative changes in seawater temperature (°C) expressed as SST anomalies in the Tasman Sea (gray) relative to the Miocene minimum SSTs reconstructed at ODP Site 1171 (5-point running average) (5), stacked record of midlatitude Southern Hemisphere temperature anomalies (blue) relative to modern SSTs (25), and modeled global deep-water temperature (dark blue) based on δ18Obenthic (50-ky running average) (1, 23). (C) δ18Oseawater (‰) as an indicator of relative salinity/precipitation for the Tasman Sea (gray; ODP Site 1171) (5) and the South China Sea (green; ODP Site 1146) (4, 28). δ18Oseawater was calculated using the δ18Obenthic stack (1) as an estimate of ice volume. (D) Modeled sea level (m) variations (black; 50-ky running average) based on δ18Obenthic (1, 23). Gray bars indicate the time intervals of major AIS expansion and onset of hypothesized increases in Antarctic sea ice (dashed arrow).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/5/e1602567/DC1

    Expedition 356 Scientists

    Supplementary Text

    fig. S1. Lithostratigraphic column for IODP Site U1464, including recovery, biostratigraphic tie points, interpreted facies, K (%), Th/K versus sediment depth, and photos of sabhka and dolostone facies.

    fig. S2. Lithostratigraphic column for IODP Site U1459 including recovery, biostratigraphic tie points, K (%), and Th/K versus sediment depth.

    fig. S3. Correlation of the K-record with K-feldspar obtained from bulk mineralogy XRD analyses plotted versus depth, and as scatter plot.

    fig. S4. T-F WFFT of the K-records from sites U1459 and U1464 along their respective biostratigraphic age model, and age versus sediment depth.

    fig. S5. T-F WFFT of the K-records from Sites U1459 and U1464 versus ETP solution (39, 42), and in comparison with those performed on the benthic δ18O records from ODP Site 1146 in the South China Sea (40) and ODP Site 1085 in the South Atlantic (41) for the same time interval.

    table S1. Biostratigraphic datums used for the biostratigraphic age model.

    table S2. Paired potassium feldspar (%), quartz (%, only shipboard; n.d., no data), and K-log (%) results versus depth in core for Site U1459.

    References (4348)

  • Supplementary Materials

    This PDF file includes:

    • Expedition 356 Scientists
    • Supplementary Text
    • fig. S1. Lithostratigraphic column for IODP Site U1464, including recovery, biostratigraphic tie points, interpreted facies, K (%), Th/K versus sediment depth, and photos of sabhka and dolostone facies.
    • fig. S2. Lithostratigraphic column for IODP Site U1459 including recovery, biostratigraphic tie points, K (%), and Th/K versus sediment depth.
    • fig. S3. Correlation of the K-record with K-feldspar obtained from bulk mineralogy XRD analyses plotted versus depth, and as scatter plot.
    • fig. S4. T-F WFFT of the K-records from sites U1459 and U1464 along their respective biostratigraphic age model, and age versus sediment depth.
    • fig. S5. T-F WFFT of the K-records from Sites U1459 and U1464 versus ETP solution (39, 42), and in comparison with those performed on the benthic δ18O records from ODP Site 1146 in the South China Sea (40) and ODP Site 1085 in the South Atlantic (41) for the same time interval.
    • table S1. Biostratigraphic datums used for the biostratigraphic age model.
    • table S2. Paired potassium feldspar (%), quartz (%, only shipboard; n.d., no data), and K-log (%) results versus depth in core for Site U1459.
    • References (43–48)

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