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Browsing by Author "Buatois, Luis"

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    Bioturbators as ecosystem engineers in space and time
    (Palaeontology, 2024) Mangano, Maria Gabriela; Buatois, Luis; Minter, Nicholas John; Gougeon, Romain
    Biogenic sedimentary structures offer a unique perspective for understanding the role of the biosphere in the interaction with other Earth subsystems and the building up of our planet. The record of their ancient equivalents provides a wealth of information for reconstructing the role of bioturbators as ecosystem engineers using multiple ichnological proxies and methods. In this study, we present an overview of how bioturbation has worked across a broad range of spatial and temporal scales from the perspective of ecosystem engineering. Comprehensive and systematic datasets allow analyses at regional and global spatial extents, and especially over long temporal scales where sampling intensity and rock record biases can be considered. Our results underscore the significance of the Cambrian Explosion in the establishment of modern-style shallow marine ecosystems and of the Ordovician Radiation for their deep marine counterparts, as well as the continuous ecosystem impact of bioturbation during Palaeozoic terrestrialization. Comparable datasets for the rest of the Phanerozoic have not yet been compiled. However, preliminary information indicates that colonization of ultra-deep tiers, the rise to prominence of regenerators, increased burrowing efficiency, and increased compartmentalization of the endobenthic ecospace, were products of the Mesozoic Marine Revolution. The trace-fossil record offers hard data to evaluate bioturbation as a driving force in ecosystem re-structuring and as a key factor in geobiological cycles. Models assessing these fundamental issues should be rooted empirically at different scales, from both autoecological and synecological to macroecological, making the best possible use of the rich and rapidly developing ichnological toolbox.
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    Evaluating Trace Fossils, Fluvial Architecture, and Colonization Patterns in Channel and Overbank Deposits from the Miocene Vinchina Formation, Vinchina Basin, Western Argentina
    (Society for Sedimentary Geology (SEPM), 2024-10-24) Valencia, Gustavo L.; Buatois, Luis; Mangano, Maria Gabriela; Farina, Martin; Krapovickas, Verónica
    Trace-fossil distribution within the framework of three-dimensional fluvial architecture has been commonly overlooked. The Miocene Vinchina Formation in western Argentina preserves extensive outcrops of fluvial deposits, including architectural elements of both anastomosing and braided systems identified along the Quebrada de La Troya. Multistorey sandy channels, amalgamated sandy channels, heterolithic multistorey channels, channels with gravel bars, abandoned channels, muddy floodplains, crevasse splays, and crevasse channels have been identified. Of these, only the deposits of three elements were bioturbated, namely crevasse splays, anastomosing abandoned channels, and braided abandoned channels. Vertical simple burrows (Skolithos isp.), large-sized J burrows (Capayanichnus vinchinensis), and simple horizontal burrows (Palaeophycus tubularis) are the most common trace fossils in the Vinchina Formation. Other elements include the horizontal meniscate trace Taenidium barretti and the vertebrate footprints Tacheria troyana, Macrauchenichnus troyana, and Ardeipeda isp. The trace-fossil assemblages identified in the Vinchina Formation collectively illustrate the Scoyenia Ichnofacies. In addition, five ichnofabrics are characterized. The position of the water table, substrate consistency, flow energy, and time between depositional events under arid to semi-arid climate conditions were the main parameters controlling bioturbation. Based on detailed observation of the cross-cutting relationship among ichnotaxa, the ichnofabric distribution and the preservation features of the trace fossils studied, a colonization sequence for each of the subenvironments of the Vinchina Formation is proposed in this study. In addition to integration with conventional facies analysis, articulating ichnologic data and fluvial architecture provides further insights into the application of trace fossils to unravel the sedimentary dynamics of alluvial systems.