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Decoupling of foreland basin subsidence from topography linked to faulting and erosion

Guy Simpson
Decoupling of foreland basin subsidence from topography linked to faulting and erosion
Geology (Boulder) (September 2014) 42 (9): 775-778


Many mountain ranges in regions of plate convergence are flanked by foreland sedimentary basins that are usually thought to result from flexing of the elastic lithosphere under the passive weight of sediments and thrust sheets emplaced in the mountain belt. However, in some places the depth of the foreland basin bears little relation to the weight of basin sediments and neighboring mountains, implying that this model is too simple and/or that additional forces must affect subsidence. Here I investigate this problem using a numerical model that incorporates coupling between an upthrusting mountain range and a subsiding basin. I show that only part of the subsidence reflected in the shape of a foreland basin is a flexural isostatic response to crustal thickening and sediment loading. The remaining subsidence results from dragging of the basin margin downward by slip on a range-front fault and related flexural deformation of the surrounding lithosphere. The maximum basin depth is shown to increase with increasing fault displacement and can become decoupled from the elevation of the mountain range, especially as erosion becomes increasingly important. Deeply eroded model mountain belts may have foreland basins several times deeper than flexural models predict on the basis of surface loads. These results challenge the prevailing view that fault-bounded foreland basins result solely from the passive weight of mountains and sediments acting on the lithosphere and they highlight that slip on major range-front reverse faults, when repeated over many earthquake cycles, may be recorded in their geometry and stratigraphic records.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 42
Serial Issue: 9
Title: Decoupling of foreland basin subsidence from topography linked to faulting and erosion
Author(s): Simpson, Guy
Affiliation: University of Geneva, Section of Earth and Environmental Sciences, Geneva, Switzerland
Pages: 775-778
Published: 201409
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2014-082778
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2014279
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201443
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