Deformation of the forearc shelf-basin by discontinuous transport. The T-thrust exists as for SPT, but it is locked intermittently, as is often proposed by those studying the geodesy of convergent margins. When the forearc shelf (Fig. 11) can no longer be subducted and the RTB-thrust becomes locked, transport compresses the forearc shelf against the North American plate deforming the forearc shelf-basin. Oceanward of the deformed basin tectonic accretion occurs as for SPT, and tectonic accretion propagates the forearc oceanward, not sedimentation in situ as for continuous transport (Fig. 8).

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