Geomorphic and Structural Controls on Facies Patterns and Sediment Composition in a Modern Foreland Basin
- M. Marzo and
- C. Puigdefábregas
Published Online: 14 APR 2009
Copyright © 1993 The International Association of Sedimentologists
How to Cite
Damanti, J. F. (1993) Geomorphic and Structural Controls on Facies Patterns and Sediment Composition in a Modern Foreland Basin, in Alluvial Sedimentation (eds M. Marzo and C. Puigdefábregas), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303995.ch17
- Published Online: 14 APR 2009
- Published Print: 16 SEP 1993
Print ISBN: 9780632035458
Online ISBN: 9781444303995
- Geomorphic and structural controls;
- Principal drainage geometries and facies products;
- straight, low-order streams perpendicular to the basin margin;
- large, complex drainage nets;
- longitudinally draining fluvial system;
- spatial distribution of lithologically distinct sediments
First-order controls on foreland-basin sedimentation can be inferred from facies patterns and sediment composition in the modern Bermejo basin of west-central Argentina. Sediment composition and texture are controlled to a great extent by drainage systems in the bounding structural provinces. The drainage networks themselves are products of complex interactions among structural style, bedrock lithology and climate.
Local drainage divides form on linear basin-bounding structures isolating portions of the sedimentary basin from sediment sources located in the interior of the mountain belt. Laterally extensive (along strike) bajada facies are produced in these areas. The distribution of bajadas is controlled by structural geometry. Sediment composition reflects the adjacent source-rock lithology.
The broad, topographically high interior of the mountain belt facilitates the formation of large integrated drainage nets that typically extend over a variety of source-rock lithologies. Point-source fans form where trunk streams fed by large drainage networks breach basin-bounding structures. Fan composition is heterogeneous reflecting the variety of lithologies exposed in the headwaters, and may contain material derived great distances (> 150 km) from the depositional site.
Variability in drainage geometry along the basin margin implies non-uniform sediment flux into the basin; the larger the drainage system the higher the sediment yield. Large drainage networks also may respond quickly to renewed uplift by releasing stored sediment. Small watersheds along the basin margin can only increase their sediment yield through increased bedrock erosion, and thus sediment supply changes may lag behind episodes of uplift.