Characteristics of two Pleistocene channel-fill deposits and their implication on the interpretation of megasequences in ancient sediments
Article first published online: 14 JUN 2006
Volume 32, Issue 1, pages 59–67, February 1985
How to Cite
LAJOIE, J. and ST-ONGE, D. A. (1985), Characteristics of two Pleistocene channel-fill deposits and their implication on the interpretation of megasequences in ancient sediments. Sedimentology, 32: 59–67. doi: 10.1111/j.1365-3091.1985.tb00492.x
- Issue published online: 14 JUN 2006
- Article first published online: 14 JUN 2006
- received 2 April 1984 revision 10 June 1984
Two Pleistocene channel fills located in two different geological settings, on Guadeloupe in the lesser Antilles and along the Coppermine River in the Northwest Territories of Canada, have different clast compositions, scale, and origin of fragmentation but have similar depositional characteristics. Massive bedding or absence of structures caused by traction, sharp non-erosive contacts, reverse coarse-tail grading, matrix-supported clasts together indicate a debris-flow mechanism in which mixtures of fine and coarse sediments moved downslope by laminar flow. Field evidence suggests subaqueous deposition for both deposits. Both bed thickness (BTh)/maximum grain size (MGS) ratios and correlations appear characteristic of subaqueous masses capable of flowing on slopes less than 1°.
The two channel fills have random BTh and MGS variations, they do not thin and fine up-section. It is suggested that fills originating from laminar mass transport could normally have random BTh and MGS up-section variations. In flysch and volcaniclastic sequences, where coarse sediments interpreted as laminar flow deposits are common, up-section BTh and MGS variations may result from processes related to source, slope, and flow characteristics rather than from the environment in which the sediments accumulate (channel).