Research ArticleGEOLOGY

Anomalous K-Pg–aged seafloor attributed to impact-induced mid-ocean ridge magmatism

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Science Advances  07 Feb 2018:
Vol. 4, no. 2, eaao2994
DOI: 10.1126/sciadv.aao2994
  • Fig. 1 The distribution of high-passed gravity and topographic anomalies by the age of the seafloor and their relationship to the timing of the Chicxulub impact.

    (A) PDFs for high-passed gravity anomalies by the age of the seafloor. White box highlights K-Pg–aged seafloor. (B) The blue line shows probabilities for gravity anomalies between 5 and 20 mgal (in percent). The black line shows the same data after subtracting the median in a 10-My wide moving window. (C and D) Same as (A) and (B), but for high-passed global seafloor topography.

  • Fig. 2 Locations of anomalous seafloor at different points in time.

    (A) Present-day locations of seafloor created within 1 My after K-Pg. Seafloor created at half-spreading rates above and below 35 mm/year are in colors and black, respectively. (B) Reconstruction with GPlates (49) of fast-spreading seafloor to locations at K-Pg time. Colors show the maximum gravity anomaly within 2° of the location before reconstruction.

  • Fig. 3 Morphology and context for the seafloor anomalies.

    (A) Distributions of anomalies near K-Pg–aged crust derived from global seafloor gravity and topography data from 60 to 70 Ma. Dashed and solid black lines (left axis) show the lognormal mean area and variance of contiguous regions exhibiting gravity anomalies greater than 5 mgal against the mean age in 1-My bins. Red line (right axis) shows the corresponding total volume of these anomalies above the mean elevation of surrounding seafloor. (B) Comparison of detrended gravity anomalies from Fig. 1B with the mean half-spreading rate for crust created at half-spreading rates above 35 mm/year.

  • Fig. 4 Comparison between oceanic gravity anomalies and other metrics of geologic change over the last 100 Ma.

    The vertical dashed line in all panels marks K-Pg. (A) The probabilities of gravity anomalies between 5 and 20 mgal for all fast-spreading seafloor and for fast-spreading seafloor in the Pacific and Indian oceans are shown by the black, blue, and orange lines, respectively. The median in a 10-My wide moving window has been subtracted from each curve. (B) Average half-spreading rates for seafloor created at half-spreading rates above 35 mm/year for the globe, Pacific Ocean, and Indian Ocean are shown by the black, blue, and orange lines, respectively. (C) Global sea level over the past 100 My (39) resampled to 1-My intervals. Values are relative to the present day.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/2/eaao2994/DC1

    section S1. Uncertainties of and modifications to the ages of the seafloor

    section S2. Probability distribution functions for all and K-Pg–aged crust

    section S3. Examples of anomalous seafloor created at K-Pg time with volume and area estimates

    section S4. Modeling of gravity anomalies

    section S5. Probability distribution functions for crust created at slow- and intermediate-spreading rates

    fig. S1. Mean error of the seafloor from the study of Müller et al. (18).

    fig. S2. Comparison between the PDFs for gravity anomalies for all and K-Pg–aged crust.

    fig. S3.Example gravity and topographic anomalies on K-Pg–aged crust.

    fig. S4. Profiles of flexurally adjusted surface (top) and Moho (middle) topography, along with free-air gravity anomaly (bottom), for a rectangular load at both top and bottom of an initially 6-km-thick plate.

    fig. S5. Required and available volumes of basalt.

    fig. S6. Compare Fig. 1 (A and B) of the main text.

    References (5054)

  • Supplementary Materials

    This PDF file includes:

    • section S1. Uncertainties of and modifications to the ages of the seafloor
    • section S2. Probability distribution functions for all and K-Pg–aged crust
    • section S3. Examples of anomalous seafloor created at K-Pg time with volume and area estimates
    • section S4. Modeling of gravity anomalies
    • section S5. Probability distribution functions for crust created at slow- and intermediate-spreading rates
    • fig. S1. Mean error of the seafloor from the study of Müller et al. (18).
    • fig. S2. Comparison between the PDFs for gravity anomalies for all and K-Pg–aged crust.
    • fig. S3. Example gravity and topographic anomalies on K-Pg–aged crust.
    • fig. S4. Profiles of flexurally adjusted surface (top) and Moho (middle) topography, along with free-air gravity anomaly (bottom), for a rectangular load at both top and bottom of an initially 6-km-thick plate.
    • fig. S5. Required and available volumes of basalt.
    • fig. S6. Compare Fig. 1 (A and B) of the main text.
    • References (50–54)

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