A Marine Incursion in the Lower Pennsylvanian Tynemouth Creek Formation, Canada:Implications for Paleogeography, Stratigraphy and Paleoecology

We document the occurrence of a marine bed, and its associated biota, in the Lower Pennsylvanian (Langsettian) Tynemouth Creek Formation of New Brunswick, and discuss its implications for paleogeography, stratigraphy, and paleoecology. This is only the second marine interval found in the entire Pennsylvanian fill of the Maritimes Basin of Canada, the other being recently found in the broadly same-age Joggins Formation of Nova Scotia. Evidence for the new marine transgression comprises an echinoderm-rich limestone that infills irregularities on a vertic paleosol surface within the distal facies of a syntectonic fluvial megafan formed under a seasonally dry tropical climate. Gray, platy ostracod-rich shales and wave-rippled sandstone beds that directly overlie the marine limestone contain trace fossils characteristic of the Mermia Ichnofacies, upright woody trees, and adpressed megafloras. This association represents bay-fills fringed by freshwater coastal forests dominated by pteridosperms, cordaites, and other enigmatic plants traditionally attributed to dryland/upland habitats. The fossil site demonstrates that marine transgressions extended farther into the interior of Pangea than has previously been documented, and may allow correlation of the Tynemouth Creek and Joggins Formations with broadly coeval European successions near the level of the Gastrioceras subcrenatum and G. listeri marine bands. It also helps explain the close similarity of faunas between the Maritimes Basin and other paleotropical basins, if transgressions facilitated migration of marine taxa into the continental interior

Reply to comment on the paper by Davies et al. “Resolving MISS conceptions and misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic processes”

We thank Noffke (2017) for her comment and for providing an opportunity to clarify our classification of “sedimentary surface textures”. We accord great credit to Dr. Noffke and other dedicated researchers whose detailed work has brought microbially induced sedimentary structures (MISS) to the widespread attention of geoscientists. However, we stand by our assertion that attributing structures observed in practical field and laboratory studies to processes of formation is much more problematic than Noffke (2017) indicates. Indeed, points in the Comment confirm the need for a classification system that categorises the degree of certainty attributed to a given interpretation. We stress that our paper was not designed as a critique of previous studies of MISS but rather was designed to encourage a reasonable assessment of uncertainty in assigning sedimentary surface textures to physical processes or to MISS

Construction Process and Post-Construction Impacts of the Palm Jumeirah in Dubai, United Arab Emirates

The Palm Jumeirah is an artificial island located in Dubai, United Arab Emirates, created through the process of land reclamation. It was developed during an economic boom in Dubai, catering to the increased tourism and luxury living requirements of the city. Design of the Palm Jumeirah started in 2001 and construction has since been completed. Two other islands, the Palm Jebel Ali and the Palm Deira, are still under construction, and are on hold indefinitely following recent financial problems and slowing property markets in Dubai. The Palm Jumeirah was designed largely to combat the problem of limited development space, especially beachfront properties. The palm shape of the island was decided on as it provided significant beachfront area, while remaining culturally relevant and symbolic. Extensive dredging and land reclamation was required to build the two sections: the outer breakwater and the inner palm shape. Throughout the reclamation process, geographical surveys were completed to ensure that the island was being shaped correctly and built up to the designed elevation. After reclamation was complete, vibrocompaction was used to compact and strengthen the sand, making it a suitable base for construction. With construction completed, the impacts of the Palm Jumeirah can be observed. Specific areas of interest are the impacts on the island itself, the surrounding geography and the ecosystem. Analysing these areas can give an indication of the success of the project, and be used to develop improved methods of design and construction for similar projects in the future. The Palm Jumeirah is one of the largest artificial islands in the world, and is a significant coastal engineering feat. Such a large-scale project is accompanied with enormous challenges and requirements. This paper provides a background on the project, describes the challenges presented in construction, and analyses post-construction impacts and future considerations

Resolving MISS conceptions and misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic processes

The rock record contains a rich variety of sedimentary surface textures on siliciclastic sandstone, siltstone and mudstone bedding planes. In recent years, an increasing number of these textures have been attributed to surficial microbial mats at the time of deposition, resulting in their classification as microbially induced sedimentary structures, or MISS. Research into MISS has developed at a rapid rate, resulting in a number of misconceptions in the literature. Here, we attempt to rectify these MISS misunderstandings. The first part of this paper surveys the stratigraphic and environmental range of reported MISS, revealing that contrary to popular belief there are more reported MISS-bearing rock units of Phanerozoic than Precambrian age. Furthermore, MISS exhibit a pan-environmental and almost continuous record since the Archean. Claims for the stratigraphic restriction of MISS to intervals prior to the evolution of grazing organisms or after mass extinction events, as well as claims for the environmental restriction of MISS, appear to result from sampling bias. In the second part of the paper we suggest that raised awareness of MISS has come at the cost of a decreasing appreciation of abiotic processes that may create morphologically similar features. By introducing the umbrella term ‘sedimentary surface textures’, of which MISS are one subset, we suggest a practical methodology for classifying such structures in the geological record. We illustrate how elucidating the formative mechanisms of ancient sedimentary surface textures usually requires consideration of a suite of sedimentological evidence from surrounding strata. Resultant interpretations, microbial or non-microbial, should be couched within a reasonable degree of uncertainty. This approach recognizes that morphological similarity alone does not constitute scientific proof of a common origin, and reinstates a passive descriptive terminology for sedimentary surface textures that cannot be achieved with the current MISS lexicon. It is hoped that this new terminology will reduce the number of overly sensational and misleading claims of MISS occurrence, and permit the means to practically separate initial observation from interpretation. Furthermore, this methodology offers a scientific approach that appreciates the low likelihood of conclusively identifying microbial structures from visual appearance alone, informing the search for true MISS in Earth's geological record and potentially on other planetary bodies such as Mars

A meta-study of relationships between fluvial channel-body stacking pattern and aggradation rate: implications for sequence stratigraphy

A quantitative comparison of 20 literature case studies of fluvial sedimentary successions tests common assumptions made in published models of alluvial architecture concerning (1) inverse proportionality between channel-deposit density and floodplain aggradation rates, and (2) resulting characteristics of channel-body geometries and connectedness. Our results do not support the relationships predicted by established stratigraphy models: the data suggest that channel-body density, geometry, and stacking pattern are not reliable diagnostic indicators of rates of accommodation creation. Hence, these architectural characteristics alone do not permit the definition of accommodation-based “systems tracts” and “settings”, and this calls into question current sequence stratigraphic practice in application to fluvial successions

La multiplication de matériel de plantation de qualité pour améliorer l'état sanitaire et la productivité des cultures : pratiques clefs pour les bananiers et les bananiers plantain. Guide illustré

Available in English, French, Spanish and Arabic, on line and on CD-ROM, this illustrated guide summarizes the key practices for producing clean planting material of banana with a high yield potential for smallholders, depending on the pests and diseases which are present. The guide is also designed to contribute to better planning of the propagation of planting material for rural development and disaster relief projects. (Résumé d'auteur

Considering river structure and stability in the light of evolution: Feedbacks between riparian vegetation and hydrogeomorphology

River ecological functioning can be conceptualized according to a four-dimensional framework, based on the responses of aquatic and riparian communities to hydrogeomorphic constraints along the longitudinal, transverse, vertical and temporal dimensions of rivers. Contemporary riparian vegetation responds to river dynamics at ecological timescales, but riparian vegetation, in one form or another, has existed on Earth since at least the Middle Ordovician (c. 450 Ma) and has been a significant controlling factor on river geomorphology since the late Silurian (c. 420 Ma). On such evolutionary timescales, plant adaptations to the fluvial environment and the subsequent effects of these adaptations on aspects of fluvial sediment and landform dynamics resulted in the emergence, from the Silurian to the Carboniferous, of a variety of contrasted fluvial biogeomorphic types where water flow, morphodynamics and vegetation interacted to different degrees. Here we identify several of these types and describe the consequences for biogeomorphic structure and stability (i.e. resistance and resilience), along the four river dimensions, of feedbacks between riparian plants and hydrogeomorphic processes on contrasting ecological and evolutionary timescales.This is the author's accepted manuscript and will be under embargo until the 18th of September 2015. The final version is available from Wiley at onlinelibrary.wiley.com/doi/10.1002/esp.3643/abstrac