Alluvial architecture of fluvio-deltaic successions: a review with special reference to Holocene settings

Abstract

Alluvial architecture has been subject of many studies because of the occurrence of natural resources in ancient fluvial successions. This paperprovides an overview of the current state of research on alluvial architecture with special reference to Holocene fluvio-deltaic settings. Severalexamples from modern fluvio-deltaic areas, especially the Holocene Rhine-Meuse delta (the Netherlands) and the Lower Mississippi Valley(U.S.A.), are used to illustrate the architectural elements that can be distinguished in fluvial successions and to show the influence of the variouscontrols on alluvial architecture (base level, climate, tectonism, aggradation, avulsion, and compaction). Avulsion is regarded as a principalprocess in the formation of fluvio-deltaic sequences, because it determines the location and number of active channels on the floodplain. Theavulsion mechanism is still subject of debate, though. A brief description of the evolution of process-based alluvial-architecture models is given.These models simulate the proportion and distribution of coarse-grained channel belts in fine-grained overbank deposits. The major drawback ofthe present-day alluvial-architecture models is the lack of (three-dimensional) quantitative field data to test and validate them. The paperconcludes with the suggestion to collect more architectural data from natural fluvial settings, to improve simulation of channel-belt geometryin alluvial-architecture models, and to implement new data and knowledge of fluvial processes into models.