Research ArticleGEOPHYSICS

Detection of a dynamic topography signal in last interglacial sea-level records

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Science Advances  07 Jul 2017:
Vol. 3, no. 7, e1700457
DOI: 10.1126/sciadv.1700457
  • Fig. 1 Interglacial sea-level sites.

    (A) Location of sea-level indicators dating to the LIG [red and black markers; from Kopp et al. (4), Hibbert et al. (27), Pedoja et al. (28), and Ferranti et al. (29)] and MIS 11 (yellow stars). The red markers denote sites at active margins (red round markers) and on islands with recent volcanic activity (red square markers). These are neglected in our analysis. Black markers denote sites at passive margins (black round markers) and oceanic islands that have not recently been deformed by volcanism (black square markers). Data at these sites were adopted in this study. Plate boundaries are shown as white lines. (B) Location of LIG sea-level indicators color-coded by type, as labeled.

  • Fig. 2 Sample distributions of observed and corrected sea-level highstands.

    (A) Distribution of the observed elevation data (4, 27, 28) after excluding outliers (8 of 298 data points) and accounting for spatial clustering of the data (see Materials and Methods). We capture the measurement uncertainty at each site by randomly sampling from the uncertainty range provided in each database. On average, we draw 10,000 samples per site. (B to E) Breakdown of the observed distribution by sea-level indicator type, as labeled (other indicators are not shown). (F to J) Observed distribution after correction for the set of four DT simulations that yield the highest correlation between predictions and observations (see fig. S8A). The mean (Embedded Image) and variance (s2) for each distribution are listed in each panel. We also indicate the correlation coefficient (R) between the data and the correction. The correlation in (F) is significant at a level of 90% (95%) if R > 0.16 (0.20). The correlations within the subsets in (G) to (J) are significant at a level of 90% (95%) if R > 0.21 (0.25), R > 0.26 (0.32), R > 0.22 (0.28), and R > 0.49 (0.59), respectively. The orange line in (A) and (F) indicates the best-fitting normal distribution, the cyan line shows a Student’s t distribution centered around the mean. Note that the variability among the different DT models follows a Student’s t distribution (see fig. S9). We used a kernel with 1-m bandwidth to calculate the maximum likelihood value (Embedded Image; black line) listed in frames (A) and (F).

  • Fig. 3 Comparison between predicted change in DT since the LIG and observed sea-level highstands.

    Mean (A) and SD (B) of the change in DT that a point moving in the local tectonic reference frame would have experienced since 125 ka computed from the 12 different convection simulations (see Materials and Methods). Note that the modeled change in DT includes the signal associated with thermal subsidence of the oceanic lithosphere. Positive values in (A) denote uplift over time. Filled circles show the mean (A) and SD (B) in DT at locations that have observations. Plate boundaries are indicated by the white areas on both plots. (C) Observed highstand elevations minus the most likely elevation (5.4 m; Fig. 2A). Note that the color bars in (A) and (C) span a different range. (D) Direct comparison between the observed highstand elevation and the predicted change in elevation due to DT. The latter reflects the mean and SD of the four preferred DT models considered in Fig. 2. Horizontal error bars correspond to uncertainties in the measurement and indicative range, which are assumed to be symmetric. Outliers are omitted in (A) to (C), but those that fall within the plotted range in (D) are shown with a gray center square. All other data points are color-coded by their indicator type. The black dotted line denotes the best-fitting linear function (intercept at −1 m, slope of 0.19 m/m).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1700457/DC1

    Supplementary Text

    fig. S1. Field examples of four distinct types of sea-level indicators.

    fig. S2. Observed and parameterized indicative meaning for corals from the database of Hibbert et al. (27).

    fig. S3. Semivariogram and kriging weights for LIG sites.

    fig. S4. Distributions of observed and corrected sea-level estimates when choosing the mean elevation across indicators at the same location (instead of the maximum).

    fig. S5. Analysis of ocean basin subsidence due to cooling.

    fig. S6. Distributions of observed and corrected sea-level highstands.

    fig. S7. Radial viscosity profiles.

    fig. S8. Relative performance of different DT models in matching variability of highstand observations.

    fig. S9. Variability among different DT predictions.

    References (5469)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Text
    • fig. S1. Field examples of four distinct types of sea-level indicators.
    • fig. S2. Observed and parameterized indicative meaning for corals from the database of Hibbert et al. (27).
    • fig. S3. Semivariogram and kriging weights for LIG sites.
    • fig. S4. Distributions of observed and corrected sea-level estimates when choosing the mean elevation across indicators at the same location (instead of the maximum).
    • fig. S5. Analysis of ocean basin subsidence due to cooling.
    • fig. S6. Distributions of observed and corrected sea-level highstands.
    • fig. S7. Radial viscosity profiles.
    • fig. S8. Relative performance of different DT models in matching variability of highstand observations.
    • fig. S9. Variability among different DT predictions.
    • References (54–69)

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