| Bioturbation affects physical and biogeochemical sediment properties creating mm- to cm-scale burrow microenvironments. Burrow microenvironments influence diagenetic processes, but previous studies discount the importance of burrow architecture at microscale levels. Studies of modern and ancient marine deposits from Canada, U.S., and Denmark presented herein investigate three aspects of burrow-mediated diagenesis: variation and description of microscale physical burrow characteristics, biogeochemical redox cycling around burrows, and burrow-mediated cementation in the rock record.;Biogeochemical examination indicates burrow structure influences redox cycling in sediments. Oxygen-diffusion profiles suggest invertebrate burrows from Willapa Bay, WA impede or enhance diffusion based on burrow architecture. In Odense, Denmark, Nereis diversicolor burrowing and irrigation activities affect iron and sulfur dynamics, favouring more oxidized species and processes in iron and sulfur cycling. Internal geochemical cycling exists within the mucous lining and burrow wall, indicating the lining and wall have distinct biogeochemical properties. Sulfur (delta34S) isotopes show a gradient from the burrow lining to the ambient sediments, likely resulting from suppressed sulfate reduction rates and reoxidation of sedimentary sulfides surrounding the burrow. Results indicate stable isotopes can preserve the effects of bioturbation, and act as effective paleoenvironmental tools.;Stable isotopic analysis of Cretaceous Rosselia socialis burrow concretions show burrow microenvironments create diagenetic effects persisting into the rock record. Isotopic signatures of carbonate cements from R. socialis burrows reveal the early cementation history, and geochemical conditions of the initial sedimentary environment. Cementation occurred near the sediment surface during methanogenesis, and prior to lithification of surrounding sediments, while cyclic and seasonal variation in the composition of depositional waters (mixed marine and groundwater) controlled cement precipitation.;The data presented herein elucidates the relationship of environment, behaviour, and burrow structure to the formation of physicochemical burrow microenvironments that affect diagenetic processes in modern and ancient deposits.;Micromorphological study shows burrowing invertebrates produce distinct burrow-wall micromorphologies. Three micromorphological characteristics distinguish intertidal burrows including grain orientation and grain-size distribution, nature of the mucous lining, and presence of wall sculpture. In continental and marine trace fossils, four proposed wall-lining types (organic, plastered, reamed and constructional) describe the variation of burrow-wall micromorphologies. |
