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Structure of coarse grained braided stream alluvium*

Published online by Cambridge University Press:  06 July 2012

B. J. Bluck
B. J. Bluck
Affiliation:
Department of Geology, University of Glasgow
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Synopsis

Grain size characteristics of the sediment and the flow stage characteristics of the river are the two most important factors influencing sedimentation in the channel zone. Climate is important in its influence on floodplain (overbank) sediment.

Supra-bar platform (upper) parts of mature bars from a wide range of climatic conditions consistently show a sequence in the development of contained sedimentary structures which is related to the flow stage. At high stage, in rivers where the bed materials are quite mobile, the bar form is not thought to be present: the form develops on the falling stage, and the bar is dissected on the lowest stage. The various bar forms have a related diagnostic structure which determined from the nature and distribution of the stratification types, and the manner of their deposition on the falling flow stage. The exposed (supra-platform) parts of lateral bars have a side and longitudinally filled inner channel which comprises fine sediment. Medial bars have converging cross-strata in sands which are overlain partly by gravels in an upward coarsening sequence.

Lateral migration of the channel zone, brought about by the preferential bar accretions to one side, results in building of a lithosome, the facies structure of which is partly determined by the nature of the bar accretions. As the channel migrates the abandoned bars may be covered with fine sediments so as to build up an upward fining sequence. The nature of the fine overbank part of the braided stream cycle is as complex as the coarse lower, so that a highly variable vertical sequence of lithological types is likely to be constructed.

Upward fining cycles are also built by some fine braided streams but they are the product of a single flood rather than lateral channel migration. Braided stream deposits are distinguishable from those of small, coarse meandering stream deposits by the presence of inner accretionary banks in the latter, and inner channels in the former.

Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 70 , Issue 10-12 , 1979 , pp. 181 - 221
Copyright
Copyright © Royal Society of Edinburgh 1979

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References

Allen, J. R. L., 1963. The classification of cross stratified units, with notes on their origin. Sedimentology, 2, 93–114.CrossRefGoogle Scholar
Allen, J. R. L., 1968. Current Ripples. Amsterdam: North-Holland Publishing Company, 433 pp.Google Scholar
Allen, J. R. L., 1973. Features of cross stratified units due to random and other changes in bed forms. Sedimentology, 20, 189–202.Google Scholar
Bertram, G. E. and Bluck, B. J. (manuscript). Upward fining terrace deposits, Southern Iceland.Google Scholar
Bluck, B. J., 1967. Deposition of some upper Old Red Sandstone conglomerates in the Clyde area: A study in the significance of bedding. Scott. J. Geol., 3, 139–167.CrossRefGoogle Scholar
Bluck, B. J., 1971. Sedimentation in the meandering river Endrick. Scott. J. Geol., 7, 93–138.CrossRefGoogle Scholar
Bluck, B. J., 1974. Structure and directional properties of some valley sandur deposits in southern Iceland. Sedimentology, 21, 533–554.CrossRefGoogle Scholar
Bluck, B. J., 1976. Sedimentation in some Scottish rivers of low sinuosity. Trans. Roy. Soc. Edinb., 69, 425–456.Google Scholar
Boothroyd, J. C. and Ashley, G. M., 1975. Processes, bar morphology, and sedimentary structures on braided fans, Northeastern Gulf of Alaska. In Glaciofluvial and Glaciolacustrine Sedimentation, eds Joplin, A. V. and McDonald, B. C.S.E.P.M. Special Publ., 23, 193–222.Google Scholar
Born, S. M. and Ritter, D. F., 1970. Modern terrace development near Pyramid Lake, Nevada, and its geologic implication. Bull. Geol. Soc. Am., 81, 1233–1242.CrossRefGoogle Scholar
Cant, D. J. and Walker, R. G., 1978. Fluvial processes and facies sequences in the sandy braided South Saskatchewan River, Canada. Sedimentology, 25, 625–648.CrossRefGoogle Scholar
Emmett, W. W., 1976. Bed load transport in two large, gravel bed rivers, Idaho and Washington. Proc. 3rd Federal Agency Conference, Denver, Colorado, 4–101.Google Scholar
Eynon, G. and Walker, R. G., 1974. Facies relationships in Pleistocene outwash gravels, southern Ontario: a model for bar growth in a braided river. Sedimentology, 21, 43–70.CrossRefGoogle Scholar
Glen, L. C., 1925. Geology and physiography of the Red River boundary between Texas and Oklahoma. Pan-Am. Gel., 43, 365.Google Scholar
Joplin, A. V., 1963. Hydraulic studies on the origin of bedding. Sedimentology, 2, 115–121.CrossRefGoogle Scholar
Karcs, I., 1972. Sedimentary structures formed by flash floods in southern Israel. Sediment. Geol., 7, 161–182.CrossRefGoogle Scholar
Klimek, K., 1972. Present-day fluvial processes and relief in the Skeidararsandur plain, Iceland. Bull. Polska Akad. Inst. Geog., 94, 1–139.Google Scholar
Mcdonald, B. C. and Banerjee, I., 1971. Sediments and bed forms on a braided outwash plain: Can. J. Earth Sci., 8, 1282–1301.CrossRefGoogle Scholar
Mcgowen, J. H. and Garner, L. E., 1970. Physiographic features and stratification types of coarse grained point bars: modern and ancient examples: Sedimentology, 14, 77–111.CrossRefGoogle Scholar
Mckee, E. D., Crosby, E. J. and Berryhill, H. L., 1967. Flood deposits, Bijou Creek, Colorado, June, 1965. J. Sedim. Petrol., 37, 829–851.CrossRefGoogle Scholar
Miall, A. D., 1977. A review of the braided river depositional environment. Earth-Sci. Rev., 13, 1–62.CrossRefGoogle Scholar
Ray, P. K., 1976. Structure and sedimentological history of the overbank deposits of Mississippi point bar. J. Sedim. Petrol., 46, 788–801.Google Scholar
Rust, B. R., 1972. Structure and process in a braided river. Sedimentology, 18, 221–245.CrossRefGoogle Scholar
Smith, N. D., 1970. The braided stream depositional environment: comparison of the Platte river with some Silurian clastic rocks, North Central Appalachians. Bull. Geol. Soc. Am., 81, 2992–3014.Google Scholar
Smith, N. D., 1971. Pseudo-planar cross stratification produced by very low amplitude sand waves. J. Sedim. Petrol., 41, 69–73.Google Scholar
Smith, N. D., 1972. Some sedimentological aspects of planar cross-stratification in a sandy braided river. J. Sedim. Petrol., 42, 624–634.Google Scholar
Smith, N. D., 1974. Sedimentology and bar formation in the upper Kicking Horse River, a braided outwash stream. J. Geol., 82, 205–224.CrossRefGoogle Scholar
Thorarinsson, S., 1956. The Thousand Years Struggle Against Ice and Fire. Boavtgefa Menningarsdjods.Google Scholar
Williams, P. F. and Rust, B. R., 1969. The sedimentology of a braided river. J. Sedim. Petrol., 39, 649–679.Google Scholar