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Book Chapter

Rift-Basin Structure and its Influence on Sedimentary Systems

By
Martha Oliver Withjack
Martha Oliver Withjack
Department of Geological Sciences, Rutgers University, Piscataivay, New Jersey 08854-8066, U.S.A.
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Roy W. Schlische
Roy W. Schlische
Department of Geological Sciences, Rutgers University, Piscataivay, New Jersey 08854-8066, U.S.A.
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Paul E. Olsen
Paul E. Olsen
Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, U.S.A.
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Published:
January 01, 2002

Abstract

Rift basins are complex features defined by several large-scale structural components including faulted margins, the border faults of the faulted margins, the uplifted flanks of the faulted margins, hinged margins, deep troughs, surrounding platforms, and large-scale transfer zones. Moderate- to small-scale structures also develop within rift basins. These include: basement-involved and detached normal faults; strike-slip and reverse faults; and extensional fault-displacement, fault-propagation, forced, and fault-bend folds.

Four factors strongly influence the structural styles of rift basins: the mechanical behavior of the prerift and synrift packages, the tectonic activity before rifting, the obliquity of rifting, and the tectonic activity after rifting. On the basis of these factors, we have defined a standard rift basin and four end-member variations. Most rift basins have attributes of the standard rift basin and/or one or more of the end-member variations. The standard rift basin is characterized by moderately to steeply dipping basement-involved normal faults that strike roughly perpendicular to the direction of maximum extension. Type 1 rift basins, with salt or thick shale in the prerift and/or synrift packages, are characterized by extensional forced folds above basement-involved normal faults and detached normal faults with associated fault-bend folds. In Type 2 rift basins, contractional activity before rifting produced low-angle thrust faults in the prerift strata and/or crystalline basement. The reactivation of these contractional structures during rifting created the low-angle normal faults characteristic of Type 2 rift basins. In Type 3 rift basins, preexisting zones of weakness in the prerift strata and/or crystalline basement strike obliquely to the direction of maximum extension, leading to oblique rifting. Type 3 rift basins are characterized by faults with strike-slip, normal, and oblique-slip displacement and with multiple trends. Contractional activity followed rifting in Type 4 rift basins. These inverted rift basins are affected by late-formed contractional structures including normal faults reactivated with reverse displacement, newly formed reverse faults, and contractional fault-bend and fault-propagation folds.

Structures within rift basins affect depositional patterns by creating sites of uplift and erosion, by controlling pathways of sediment transport, and by defining the accommodation space for sediment deposition and preservation. The relationships among basin capacity (structurally controlled), sediment supply, and water supply determine the primary depositional regime in nonmarine rift basins, fluvial or lacustrine. Changes in basin capacity resulting from the growth of a rift basin may yield a tripartite stratigraphy (fluvial, deep lacustrine, and shallow lacustrine-fluvial) common to many nonmarine rift basins.

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Contents

SEPM Special Publication

Sedimentation in Continental Rifts

Robin W. Renaut
Robin W. Renaut
Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
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Gail M. Ashley
Gail M. Ashley
Department of Geological Sciences, Rutgers University, Piscataway, New Jersey 08854-8066, U.S.A.
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SEPM Society for Sedimentary Geology
Volume
73
ISBN electronic:
9781565761957
Publication date:
January 01, 2002

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