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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 64 (1980)

Issue: 5. (May)

First Page: 792

Last Page: 793

Title: Slope-Centered Processes in Santa Barbara Basin, California Borderland: ABSTRACT

Author(s): Scott E. Thornton

Article Type: Meeting abstract

Abstract:

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Three basic types of slope-centered processes are responsible for the infilling of Santa Barbara basin: low-concentration suspenate transport, large-scale glides, and small-scale processes which consist of a continuum of slumps to debris flows. Suspensate transport is concentrated on the northeast part of the basin and is perhaps channeled by the Montalvo trough. Large-scale glides extend across the entire northern slope and are most spectacular in the Montalvo trough where higher sedimentation rates due to suspensate transport seem to speed the process. Small-scale slump to debris-flow deposits can be found at six specific sites. These deposits exhibit fluid escape structures, dish structures, a swirled x-radiograph signature, and in some deposits dramatic, matrix-supported, random f brics with clasts as large as 4 cm. Laminations provide key markers necessary to discern distortion of sediment in areas of mass movement. The deep basin-floor laminated zone is laminated due to low oxygen content of the water column and deposition of gray layers due to suspensate transport during exceptionally rainy winters. Even parts of this laminated zone appear to be involved in gradual glides. In shallow parts of the basin on the northeast side, laminations are of a different type and are produced by years of suspensate transport. This laminated zone is centered along the axis of the Montalvo trough. High sedimentation rates apparently prevented destruction of the laminations due to bioturbation. Only a relatively small part of the deep basin floor, a flat area which slopes very gr dually to the south, is somewhat immune to mass movement. However, fluidal flows generated by mass flows upslope could conceivably reach this area and result in unusually thick laminations.

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