The role of transverse drainage in the development of foreland folds
- Pennsylvania State Univ., University Park, PA (United States)
It is a fact of some consequence that transverse streams in active fold and thrust belts often lie atop the culminations of the principal anticlines. The conventional explanation for this association is discordant superposition of transverse subsequent streams. Here the authors present the alternative hypothesis that antecedent transverse rivers maintain their courses during deformation, thereby effecting greater denudation rates in their vicinity. These higher rates unload fault bends and thrust tips, thus facilitating local fold growth. To test this hypothesis, a two-dimensional finite element program (TECTON) is employed to assess the effects of mass removal on the growth and propagation of folds in the Zagros foreland of Iran. The model encompasses a varying lithology, in accordance with the local stratigraphic column. A single thrust sheet with a ramp dipping at 30[degree], represents the main Zagros thrust. The author applies a horizontal pressure force of 3.8 [times] 10[sup 11] Pascals and simulate weathering by applying upward directed forces equal to the weight of material eroded off during a timestep. Results show that increased denudation of an emerging range not only enhances fold growth, but also facilitates propagation of the buckle folds. This arises because the total work performed in the development of a duplex fold is dominated by the work needed to move thrust slices up-section against the force of gravity. They therefore hypothesize that mass unloading in the very early stages of an orogen can plan an important role in the overall development of the mountain belt.
- OSTI ID:
- 5935264
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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