Biogenic sedimentary structures decrease in diversity and abundance with increasing water depth across the size-graded shelf of south-central Texas. Regional biorurbation patterns are related to macrobenthic infaunal assemblages and sediment facies. Dense and diverse assemblages of biogenic sedimentary structures are associated with shallow-water areas with relatively coarse substrates, low sedimentation rates, and dense and diverse infaunal assemblages. The outer shelf zone exhibits little biorurbation due to the presence of very few organisms, high sedimentation rates, and an underconsolidated substrate of muddy sediments of near-uniform grain size. Most traces have limited distribution ranges, high preservation potential, and vertical to subvertical orientation (or represent deep subhorizontal burrowing). In the rock record, estimating the degree of bioturbation in mud beds is the key to correctly interpreting regional bioturbation patterns for size-graded shelf deposits.
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Organisms of one sort or another today inhabit virtually every sediment environment on Earth, and the rock record tells us that this has been the case through the greater part of our planet’s history. Furthermore, organisms leave their mark in most sedimentary settings, either directly in the form of body fossils or indirectly as biogenic structures. In addition to their often profound modifying effects on substrates, ancient biogenic structures preserve a record of organism behavioral activity in response to substrate and other paleoenvironmental controls. Thus, biogenic structures can be highly useful as facies indicators and can provide valuable clues to the interpretation of paleodepositional environments. The purpose of this volume is to present a broad spectrum of case-book examples of the use of biogenic structures in the interpretation of depositional environments.