Engineering the Cambrian explosion: the earliest bioturbators as ecosystem engineers

By applying modern biological criteria to trace fossil types and assessing burrow morphology, complexity, depth, potential burrow function and the likelihood of bioirrigation, we assign ecosystem engineering impact (EEI) values to the key ichnotaxa in the lowermost Cambrian (Fortunian). Surface traces such as Monomorphichnus have minimal impact on sediment properties and have very low EEI values; quasi-infaunal traces of organisms that were surficial modifiers or biodiffusors, such as Planolites, have moderate EEI values; and deeper infaunal, gallery biodiffusive or upward-conveying/downward-conveying traces, such as Teichichnus and Gyrolithes, have the highest EEI values. The key Cambrian ichnotaxon Treptichnus pedum has a moderate to high EEI value, depending on its functional interpretation. Most of the major functional groups of modern bioturbators are found to have evolved during the earliest Cambrian, including burrow types that are highly likely to have been bioirrigated. In fine-grained (or microbially bound) sedimentary environments, trace-makers of bioirrigated burrows would have had a particularly significant impact, generating advective fluid flow within the sediment for the first time, in marked contrast with the otherwise diffusive porewater systems of the Proterozoic. This innovation is likely to have created significant ecospace and engineered fundamentally new infaunal environments for macrobiotic and microbiotic organisms alike

The impact of seismic interpretation methods on the analysis of faults: a case study from the Snøhvit field, Barents Sea

Five seismic interpretation experiments were conducted on an area of interest containing a fault relay in the Snøhvit field, Barents Sea, Norway, to understand how the interpretation method impacts the analysis of fault and horizon morphologies, fault lengths, and throw. The resulting horizon and fault interpretations from the least and most successful interpretation methods were further analysed to understand their impact on geological modelling and hydrocarbon volume calculation. Generally, the least dense manual interpretation method of horizons (32 inlines and 32 crosslines; 32 ILs × 32 XLs, 400 m) and faults (32 ILs, 400 m) resulted in inaccurate fault and horizon interpretations and underdeveloped relay morphologies and throw, which are inadequate for any detailed geological analysis. The densest fault interpretations (4 ILs, 50 m) and 3D auto-tracked horizons (all ILs and XLs spaced 12.5 m) provided the most detailed interpretations, most developed relay and fault morphologies, and geologically realistic throw distributions. Sparse interpretation grids generate significant issues in the model itself, which make it geologically inaccurate and lead to misunderstanding of the structural evolution of the relay. Despite significant differences between the two models, the calculated in-place petroleum reserves are broadly similar in the least and most dense experiments. However, when considered at field scale, the differences in volumes that are generated by the contrasting interpretation methodologies clearly demonstrate the importance of applying accurate interpretation strategies.publishedVersio

The co-evolution of biology anf taphonomy across the proterozoic-cambrian transition

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Physical, biological, geochemical and sedimentological controls on the ichnology of continental slope channel systems

RC acknowledges the support of a postdoctoral fellowship from the PRACSS Consortium (funded by BG Group, BP, DONG, RWE Dea, Petrochina, Statoil and Tullow Oil). DMc acknowledges the financial support of a Canada Research Chair and an NSERC Discovery Grant. Our colleagues Bryan Cronin, Fabiano Gamberi, Larissa Hansen, Liam Herringshaw and Christopher Phillips are thanked for their discussions and comments. Elisabeth Kahlmeyer is thanked for assistance with drafting. We are grateful for the helpful advice and constructive feedback from the reviewers Steve Hubbard and David Hodgson, whose suggestions greatly strengthened the manuscript.Peer reviewedPostprin

Osmotrophic biofilms: from modern to ancient

Biofilms and microbial mats can be regarded as among the most vigorous and\ud ancient ecosystems found on Earth (Noffke et al., 2006). In contrast with planktonic\ud microbes, the extracellular polymeric substance in which they are usually\ud embedded renders the microbes in biofilms relatively resilient to adverse environmental\ud changes (Costerton and Stoodley, 2003). Biofilms are usually multilayered\ud and involve consortia of microbes, in which all the materials needed to sustain\ud life can be recycled (Stolz, 2003). A viable microbial mat is therefore quite likely\ud to contain a mixture of autotrophic fixers of carbon dioxide, heterotrophic consumers\ud that feed by ingestion of organic particles, and others that have adapted\ud to recycle the preformed organic matter by means of enzymatic digestion and\ud absorption through the cell wall – called osmotrophy

Osmotrophic biofilms: from modern to ancient

Biofilms and microbial mats can be regarded as among the most vigorous and ancient ecosystems found on Earth (Noffke et al., 2006). In contrast with planktonic microbes, the extracellular polymeric substance in which they are usually embedded renders the microbes in biofilms relatively resilient to adverse environmental changes (Costerton and Stoodley, 2003). Biofilms are usually multilayered and involve consortia of microbes, in which all the materials needed to sustain life can be recycled (Stolz, 2003). A viable microbial mat is therefore quite likely to contain a mixture of autotrophic fixers of carbon dioxide, heterotrophic consumers that feed by ingestion of organic particles, and others that have adapted to recycle the preformed organic matter by means of enzymatic digestion and absorption through the cell wall – called osmotrophy

Martin Brasier's contribution to the palaeobiology of the Ediacaran–Cambrian transition

Martin Brasier's work spanned almost the entire geological column, but the origin of animals and the nature of the Cambrian explosion were areas of particular interest to him. Martin adopted a holistic approach to the study of these topics that considered the interplay between multiple geological and biological phenomena and he sought to interpret the fossil record within the broad context of geological, biogeochemical and ecological changes in the Earth system. Here we summarize Martin's main contributions to this area of research and assess the impact of his findings on the development of this field

Genesis and character of thin-bedded turbidites associated with submarine channels

Acknowledgements We acknowledge the support of the PRACSS Joint Industry Project at University of Aberdeen, funded by BG Group, BP, DONG, RWE Dea, Petrochina, Statoil and Tullow Oil. We also acknowledge the entire crew of the Urania Research vessel which was used to acquire the CHIRP lines, bathymetric data and gravity cores from the Tyrrhenian Sea, Italy. Our colleagues Michal Janocko and Mike Mayall are thanked for the discussions and comments. Our colleagues Pan Li, Amanda Santa Catharina, Guilherme Bozetti and Matheus Silveira Sobiesiak are thanked for their assistance during field work where some of the ideas in this paper were synthesized. Finally we thank one anonymous reviewer and Brian Romans for their invaluable feedback which made some of the ideas introduced in this review much more succinct.Peer reviewedPostprin