Research ArticleCLIMATE MODELING

Autogenic geomorphic processes determine the resolution and fidelity of terrestrial paleoclimate records

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Science Advances  13 Sep 2017:
Vol. 3, no. 9, e1700683
DOI: 10.1126/sciadv.1700683

Figures

  • Fig. 1 Schematic example of time series recovered from stratigraphy and experimental setup.

    (A) Construction of stratigraphic column from individual depositional and erosional events of varying magnitude and rate. These geomorphic events discretize the proxies preserved in the resultant stratigraphy and the coeval time series of climatic variation [red circles are time periods represented in the recovered climate change record (B)]. (C) Illustration of compensation behavior in cross section as a basin subsides. (D) Schematic illustration and overhead photograph of the experiment (dashed line denotes the position of topography scans).

  • Fig. 2 Example time series of climatic changes.

    The true climate variation is shown as gray lines, and the climate time series produced by linear interpolation between depositional events by proxy data points are shown as white circles, with a three-point running average of proxy data points (black line).

  • Fig. 3 REDFIT power spectra of proxy-derived paleoclimate data.

    (A) Spurious and inaccurate climate oscillations identified until the period of climate oscillation is twice the compensation time scale. (B) “Shredding” and signal loss until the period of climate oscillation is twice the compensation time scale. Frequency is scaled by the compensation time scale shown as a blue vertical line, and the true paleoclimate frequency of oscillation is shown as a gray vertical line.

  • Fig. 4 REDFIT power spectra of randomly fluctuating paleoclimate and bed thicknesses.

    (A) Example power spectra of random climate time series showing no significant periodicities. C.L., confidence limit. (B) Example power spectra of random climate time series identifying spurious oscillations shorter and longer than Tcomp. (C) Spurious oscillation at the time scale of Tcomp. (D and E) Example power spectra from bed thickness variations showing no repetitive cycles (D) and a spurious oscillation (E). Frequency is scaled by the compensation time scale shown as a blue vertical line.

  • Fig. 5 A comparison of representative time scales of major climatic variations known operating in the modern system and past geologic events with an estimated range of compensation time scales in alluvial systems (27).

    ENSO, El Niño–Southern Oscillation; PDO, Pacific Decadal Oscillation; NAO, North Atlantic Oscillation; OAEs, ocean anoxia events; LIPs, large igneous provinces.

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