Research ArticleGEOPHYSICS

Lateral propagation–induced subduction initiation at passive continental margins controlled by preexisting lithospheric weakness

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Science Advances  04 Mar 2020:
Vol. 6, no. 10, eaaz1048
DOI: 10.1126/sciadv.aaz1048
  • Fig. 1 Major convergent margins with possible lateral propagation of SI.

    The preexisting faults can be transform faults or STEP. STEP, Subduction-Transform Edge Propagator. Topography data are from ETOPO1 Global Relief Model (www.ngdc.noaa.gov/mgg/global/). The topographic map is produced by the Generic Mapping Tools (64).

  • Fig. 2 Initial model setup illustrating geometry, lithologies, and thermal configurations.

    (A) 3D model domain with colors indicating different lithologies as shown in the color bar at the bottom left. The top layer of sticky air is cut off for clarity. (B) XY slice at Z = 1000 km through the intraoceanic subduction zone. (C and D) XY slice at Z = 1750 km through the passive continental margins, with (D) or without (C) a preexisting lithospheric weak zone. The white lines in (B) to (D) denote isotherms, starting from 100° to 1300°C with 400°C intervals.

  • Fig. 3 Numerical model evolution with stable continental margin (no preexisting weak zone).

    (A to C) Model snapshots at 2.55 Ma, 4.21 Ma, and 5.58 Ma, respectively. (Left column) Subducting slab morphology by temperature field. (Middle column) Relative surface elevation. (Right column) Second invariant of strain rate tensor of the horizontal depth slice at Y = 80 km. Tearing along the lateral edges of the subducting slab to form a STEP fault is predicted. See detailed model evolution in movie S1.

  • Fig. 4 Numerical model evolution with a weakened passive continental margin (preexisting weak zones in the OCT regions).

    (A to D) Model snapshots at 2.81 Ma, 4.42 Ma, 5.79 Ma, and 6.96 Ma, respectively. For explanation of panel meanings, see Fig. 3 caption. Lateral propagation–induced SI at passive continental margin is predicted. See detailed model evolution in movie S2.

  • Fig. 5 Schematic regimes of 3D subduction mode selection.

    (A to C) Regime diagrams correspond to different strain weakening effects. The effects of three controlling factors are investigated: the age of subducting oceanic lithosphere, the friction coefficient of passive continental margin weak zones, and the strain weakening of lithospheric mantle. Numerical results are summarized into three contrasting modes: subducting slab tearing along STEP faults [(D) green], lateral propagation–induced SI at passive continental margin [(E) blue], and aborted subduction with slab break-off [(F) red]. The typical model evolutions of (D) and (E) are shown in Figs. 3 and 4, respectively. The detailed model evolution of slab break-off (F) is shown in movie S3.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/10/eaaz1048/DC1

    Fig. S1. Additional model results with variable widths (10 to 40 km) of the OCT weak zones, in comparison to the reference models with preexisting OCT weak zones of 50 km (i.e., top).

    Fig. S2. Additional models with a prescribed weak zone only existing in one of the neighboring passive margins.

    Fig. S3. Additional models with variable lengths of the preexisting subducted oceanic slab.

    Fig. S4. The tectonic map of the Caribbean region.

    Table S1. Physical properties of materials used in the numerical experiments.

    Table S2. Parameters of the numerical models and the results.

    Movie S1. Animation of the STEP formation mode.

    Movie S2. Animation of the SI propagation mode.

    Movie S3. Animation of the aborted SI with slab break-off mode.

    References (6567)

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Additional model results with variable widths (10 to 40 km) of the OCT weak zones, in comparison to the reference models with preexisting OCT weak zones of 50 km (i.e., top).
    • Fig. S2. Additional models with a prescribed weak zone only existing in one of the neighboring passive margins.
    • Fig. S3. Additional models with variable lengths of the preexisting subducted oceanic slab.
    • Fig. S4. The tectonic map of the Caribbean region.
    • Table S1. Physical properties of materials used in the numerical experiments.
    • Table S2. Parameters of the numerical models and the results.
    • References (6567)

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Animation of the STEP formation mode.
    • Movie S2 (.mp4 format). Animation of the SI propagation mode.
    • Movie S3 (.mp4 format). Animation of the aborted SI with slab break-off mode.

    Files in this Data Supplement:

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