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.
Clustering of Elongate Muddy Delta Lobes within Fluvio–Lacustrine Systems, Jurassic Kayenta Formation, Utah
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Published:January 01, 2016
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CiteCitation
Galen Huling, John Holbrook, 2016. "Clustering of Elongate Muddy Delta Lobes within Fluvio–Lacustrine Systems, Jurassic Kayenta Formation, Utah", Autogenic Dynamics and Self-Organization in Sedimentary Systems, David A. Budd, Elizabeth A. Hajek, Sam J. Purkis
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Abstract
The Kayenta Formation, Warner Valley, Utah, shows lateral and vertical clustering of mud-delta propagating-channel sand bodies within a matrix of fine-grained open-lake deposits and further provides opportunity to develop a fluvio-deltaic depositional-process model. Clustering due to nonrandom stream avulsion is well documented for high-accommodation fluvial systems operating in alluvial plains but not well established for lacustrine systems with abundant fluvio-deltaic lobes. Kayenta Formation delta lobes have similar spatial clustering to those observed in fluvial channel belts and possibly extend this clustering concept to fluvio-lacustrine systems. Lithofacies were mapped on three large photo panoramas, and architectural-element analysis was used to identify bounding surfaces of fluvial channel-deltaic lobes. Fluvio-lacustrine delta lobes reflect linear channels that propagate across mud deltas with negligible bifurcation and generate fluvial channel belts incised into lake mudstone. Channels are associated with thin sand sheets or “blow-out wings” that extend multiple channel widths from the channel and cover levee and mud-delta deposits, but delta-front sand beds are absent. The stages of evolution for these propagating channels is preserved in the variation of channel-lobe architecture and reflects mud-delta propagation at the mouth of each channel in the absence of delta-front sand. Sand is outpaced by mud in the ever-lengthening channel, which reduces sand at the channel mouth and diminishes necessity for channel bifurcation. The resulting deposit is thus a frontal mud-delta lobe bisected by a later single sandy channel belt with lateral sand wings. Statistical analysis of these channel belts shows clustering. Clustering of fluvial bodies within shallow lakes is significant in predictive reservoir models because it improves connectivity and localization of delta-lobe reservoirs. The clustering of delta lobes in fluvio-lacustrine systems is theorized to reflect the preferential channel avulsion centered on the axis of the primary channel feeding into the lake and preferential avulsion fairways of feeder channels. Both the segregation of sand and mud though channel lengthening and the clustering are explainable in fully autocyclic terms. The needed allocyclic driver to trigger these fluvio-lacustrine processesis an accommodation rate sufficiently low compared with lake filling rate as to maintain shallow-water conditions across the lake system through multiple generations of channel propagation.
- aggradation
- Alberta
- avulsion
- Canada
- clastic rocks
- connectivity
- deltaic environment
- floodplains
- fluvial environment
- fluvial features
- fluviolacustrine environment
- Jurassic
- Kayenta Formation
- lacustrine environment
- lithofacies
- Mesozoic
- modern analogs
- mudstone
- planar bedding structures
- reservoir properties
- reservoir rocks
- sand bodies
- sedimentary rocks
- sedimentary structures
- shallow-water environment
- statistical analysis
- United States
- Utah
- Western Canada
- Warner Valley
- Lake Zama