Frank G. Ethridge, 1985. "Modern Alluvial Fans and Fan Deltas", Recognition of Fluvial Depositional Systems and their Resource Potential, Romeo M. Flores, Frank G. Ethridge, Andrew D. Miall, William E. Galloway, Thomas D. Fouch
Download citation file:
Alluvial fans constitute a distinct landform and depositional system characteristic of piedrrnt areas. Fisher and Brown (1972) describe alluvial fans as cone-shaped piles of sediment built where streams issue from a highland into an adjacent lowland. Fan deltas and clastic wedges are related features that belong under the same general heading of Fan Systems. Fan deltas are alluvial fans that build into a standing body of water (ocean, sea, lake, etc.). They generally have a distinct group of distal environments that owe their existance to this body of water. Proximal environments of fan deltas and alluvial fans are quite similar. Clastic wedges comprise a series of overlapping alluvial fan and/or fan delta deposits. The term clastic wedge has generally been applied to these thick sequences of coarse detrital units associated with fault block rrountains.
Bull (1962, 1963, 1964 and 1968) conducted extensive investigations of rrdern, arid and semi-arid region alluvial fans. These investigations are summarized in two later papers (Bull, 1972 and 1977). Morphologically arid-region alluvial fans are cone-shaped deposits that can be divided into three geornorphologic units: fan head (proximal fan), mid fan, and fan base (distal fan; Fig. 1C). Arid-region alluvial fans generally displays a concave longitudinal profile (Fig. 1C) and a convex transverse profile (Fig. 1B). Fan surfaces slope from less than 1m to about 40m/km. Individual fans have lengths of i to 6 km and areas of 1 sq km to 900 sq km (Fisher and Brown, 1972; Spearing, 1975) although coalescing fans can form laterally
Figures & Tables
The understanding of fluvial environments and processes that operate within them as well as their products in the geological record is a recent development. During the past decade, facies analysis of fluvial rocks has been increasingly used to explore for and develop hydrocarbons, coal, uranium and metallic minerals. The rapid growth in the database on fluvial depositional systems coupled with the need to recognize the economic potential of their deposits has yielded numerous resources which deal with recognition and classification of the whole spectrum of fluvial systems, fluvial processes and their products, facies models of ancient fluvial deposits, and application of fluvial models to resource exploration and development. This notebook is an outgrowth of the burgeoning geological investigations of fluvial rocks and their associated potential. The notebook is divided into 11 chapters the cover methodology and classification of fluvial systems as well as modern and ancient deposits of alluvial fans, fan deltas, braided systems, meandering streams and anastomosed streams. In addition, application of facies modeling to exploration and development of hydrocarbons, coal and uranium is discussed for the Rocky Mountain region, Mid Continent, Gulf Coast and western China.