Mountains, monsoons, and megafans

Research output: Contribution to journalArticlepeer-review

149 Scopus citations

Abstract

In certain cases, the rivers draining mountain ranges create unusually large fan-shaped bodies of sediment that are referred to as fluvial megafans. We combine information from satellite imagery, monthly discharge and precipitation records, digital elevation models, and other sources to show that the formation of fluvial megafans requires particular climatic conditions. Specifically, modern fluvial megafans in actively aggrading basins are produced by rivers that undergo moderate to extreme seasonal fluctuations in discharge that result from highly seasonal precipitation patterns. The global distribution of modern megafans is primarily restricted to 15°-35° latitude in the Northern and Southern Hemispheres, corresponding to climatic belts that fringe the tropical climatic zone. No relationship exists between megafan occurrence and drainage-basin relief or area. The tendency of rivers with large fluctuations in discharge to construct megafans is related to the instability of channels subject to such conditions. Because of the correlation between seasonal precipitation and megafan occurrence, the recognition of fluvial megafan deposits in ancient stratigraphic successions may provide critical information for paleoclimate reconstructions.

Original languageEnglish (US)
Pages (from-to)289-292
Number of pages4
JournalGeology
Volume33
Issue number4
DOIs
StatePublished - Apr 2005

Keywords

  • Avulsion
  • Fluvial
  • Megafan
  • Monsoon
  • Paleoclimate
  • Sedimentation

ASJC Scopus subject areas

  • Geology

Fingerprint Dive into the research topics of 'Mountains, monsoons, and megafans'. Together they form a unique fingerprint.

Cite this