Biological Self-Organization: Implications for Sedimentary Rocks with Examples From Shallow Marine Settings
Published:January 01, 2016
Thomas D. Olszewski, 2016. "Biological Self-Organization: Implications for Sedimentary Rocks with Examples From Shallow Marine Settings", Autogenic Dynamics and Self-Organization in Sedimentary Systems, David A. Budd, Elizabeth A. Hajek, Sam J. Purkis
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Self-organization refers to the emergence of large-scale ordered pattern starting from initially disordered conditions through small-scale interactions between components of a system. Although the influence of biological agents on sediments and landscapes is widely appreciated by sedimentary geologists, the role of life in sedimentary self-organization is less familiar. One of the oldest ecological concepts relevant to self-organization is ecological succession, which is the idea that species colonization of a virgin or a disturbed landscape follows a series of more or less orderly and predictable changes in taxonomic composition and habitat structure. Many early studies of ecological succession in the fossil record confounded allogenic facies succession reflecting environmental shifts with autogenic ecological changes driven by organism interactions. However, evidence for autogenic ecological succession can be found in a variety of depositional contexts and is particularly evident in environments that are influenced by ecosystem engineers (organisms that affect other species by physically modifying or building their habitats), like reefs and shell beds. In addition to influencing change in an ecosystem over time, biologically mediated feedbacks can also produce highly organized spatial patterns. The basic mechanism of spatial self-organization requires at least one negative feedback loop that acts at a distance. Although relatively few examples have been documented in the rock record, self-organized spatial dynamics have the potential to greatly influence the nature of depositional environments by altering the flow of matter and energy. Recognition of biotic feedbacks is necessary for a complete and predictive understanding of the architecture of the stratigraphic record, and it seems likely that with greater awareness of self-organization and autogenesis in the sedimentary record, the numberof biologically mediated examples will increase.
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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.