Autogenic Dynamics and Self-Organization in Sedimentary Systems
Autogenic dynamics and self-organization in sedimentary systems are increasingly viewed as significant and important processes that drive erosion, sediment transport, and sediment accumulation across the Earth’s surface. These internal dynamics can dramatically modulate the formation of the stratigraphic record, form biologically constructed depositional packages, affect ecological patterning in time and space, and impact aspects of geochemical sedimentation and diagenesis. The notion that autogenic processes are local phenomena of short duration and distance is now recognized as false. Understanding autogenic dynamics in sedimentary systems is thus essential for deciphering the morphodynamics of moderns sedimentary systems, accurately reconstructing Earth history, and predicting the spatial and temporal distribution of sedimentary and paleobiologic features in the stratigraphic record. The thirteen papers in this volume present exciting new ideas and research related to autogenic dynamics and self-organization in sedimentology, stratigraphy, ecology, paleobiology, sedimentary geochemistry, and diagenesis. Five papers summarize the current state of thinking about autogenic processes and products in fluvial-deltaic, eolian, and carbonate depositional systems, and in paleobiologic and geochemical contexts. A second group of papers provide perspectives derived from numerical modeling and laboratory experiments. The final section consists of field studies that explore autogenic processes and autogenically modulated stratigraphy in five case studies covering modern and ancient fluvial, deltaic, and shelf settings. This SP should stimulate further research as to how self-organization might promote a better understanding of the sedimentary record.
A Mind of Their Own: Recent Advances in Autogenic Dynamics in Rivers and Deltas
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Published:January 01, 2016
Abstract
The science of the internally generated behavior and spatial organization of depositional systems has come a long way since Beerbower first coined the term “autocycles” to refer to fining-upward sequences generated by river meander migration, cutoff, and eventual return. Ongoing research has broadened the scope and scale range of known autogenic dynamics, even as a unifying theme—sediment storage and release—has emerged. Many internally generated processes do not have a single characteristic length or time scale but rather occupy a broad scale range (hence, “autocyclic” has been gradually replaced by “autogenic”). But even where they are broad, the scale ranges for autogenic processes are bounded by limiting time and length scales. The central role of sediment storage and release provides a means of estimating these limiting length and time scales based on mass balance, geometry, and mean sediment flux. Recent research has also allowed us to expand the upper limits of autogenic behavior to time scales of 105 to 106 years. Finally, we recognize that autogenic dynamics is not simply superimposed on allogenic signals but interacts strongly with, modifies, and even destroys allogenic input. That the autogenic imprint on the stratigraphic record is stronger and more complex than once thought can be seen as an opportunity to focus on using the record to learn about intrinsic surface behavior under pre-human conditions, rather than simply as an archive of externally imposed signals.
- avulsion
- bars
- bedforms
- bedload
- channels
- deltaic sedimentation
- deltas
- dynamics
- experimental studies
- fluvial environment
- fluvial features
- fluvial sedimentation
- laboratory studies
- mass balance
- meanders
- rivers
- sediment transport
- sedimentation
- sediments
- storage
- stream sediments
- transport
- autogenic processes