Short-Term Evolution of Primary Sedimentary Surface Textures (Microbial, Abiotic, Ichnological) on a Dry Stream Bed: Modern Observations and Ancient Implications

Davies, Neil S.; Shillito, Anthony P.; McMahon, William J.

doi:10.2110/palo.2016.064

Cited by 23 publications

(23 citation statements)

References 27 publications

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“…Exposure surfaces are common and associated with this is the frosting of grains which would provide evidence for aeolian modification of exposed sands. Davies et al (2017) interpreted the surface in Fig. 5G as a shallow pond feature with ripples in the deepest part, a smooth pond margin and adhesion structures around the edges of the wet pond.…”

Section: Discussionmentioning

confidence: 99%

“…Davies et al . () interpreted the surface in Fig. G as a shallow pond feature with ripples in the deepest part, a smooth pond margin and adhesion structures around the edges of the wet pond.…”

Section: Lithofacies Descriptionsmentioning

confidence: 97%

“…G, where it can be seen that the ripples are being deformed into the flow, which is interpreted as a washout structure from surface run‐off during low tide. This is important because previous interpretations (Davies et al ., ) have suggested a subaerial to entirely continental origin for the formation of this structure. Deposition was under sub‐marine conditions and later subaerial exposure modified the ripples into adhesion structures and run‐off structures dissected and washed out the ripples.…”

Section: Lithofacies Descriptionsmentioning

confidence: 98%

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The applicability of modern tidal analogues to pre‐vegetation paralic depositional models

et al. 2018

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In modern siliciclastic environments terrestrial and aquatic vegetation binds substrate, controls weathering and erosion rates, influences run-off, sediment supply and subsequent depositional architecture. This study assesses the applicability of modern depositional models that are impacted by vascular vegetation, as analogues for ancient pre-land plant systems. A review of pre-Devonian published literature demonstrates a paucity of described tidal successions; this is possibly due to the application of modern analogues for interpreting the record when there is a lack of tidal indicators. This paucity suggests a need for revised models of tidal deposition that consider the different environmental conditions prior to land plant evolution. This study examines the OrdovicianSilurian Tumblagooda Sandstone, which is exposed in the gorge of the Murchison River and coastal cliffs near Kalbarri, Western Australia. The Tumblagooda Sandstone comprises stacked sand-rich facies, with well-preserved bedforms and trace fossils. Previous interpretations of the depositional setting have proposed from a mixed sheet-braided fluvial and intertidal flats; to a continental setting dominated by fluvial and aeolian processes. An enigmatic element is the rarity of mud-rich facies preserved in the succession. Outcrop logging, facies and petrographic analysis record dominantly shallow water conditions with episodes of emergence. Abundant ichnotaxa indicate that marine conditions and bi-directional flow structures are evidence for an intertidal and subtidal depositional environment. A macrotidal estuary setting is proposed, with evidence for tidal channels and repeated fluvial incursions. Physical and biogenic sedimentary structures are indicative of tidal conditions. The lack of clay and silt resulted in the absence of flaser or lenticular-bedding. Instead cyclic deposition of thin beds and foreset bioturbation replaced mud drape deposits. Higher energy conditions prevailed in the absence of the binding activity of plants in the terrestrial and marine realm. This is suggestive of different weathering processes and a reduction in the preservation of some sedimentary features.

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Section: Discussionmentioning

confidence: 99%

Section: Lithofacies Descriptionsmentioning

confidence: 97%

Section: Lithofacies Descriptionsmentioning

confidence: 98%

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The applicability of modern tidal analogues to pre‐vegetation paralic depositional models

et al. 2018

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“…This is particularly the case for bedding planes that we here distinguish with the term "true substrates": fossilized sediment-water (or sedimentair) interfaces that are the plan-view equivalents of chronostratigraphic surfaces in vertical profile (i.e., synoptic or sampled topography; Ganti et al, 2013;Paola et al, 2018). Not all true substrates can be recognized as such (Dott, 1983), but many can, particularly where they maintain an original morphology from the time of deposition (e.g., ripple marks) or host surficial ichnologic, biotic, sedimentary, petrographic, or pedogenic signatures (e.g., Miall and Arush, 2001;Davies et al, 2017).…”

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confidence: 99%

Incomplete but intricately detailed: The inevitable preservation of true substrates in a time-deficient stratigraphic record

Davies

Shillito

2018

Geology

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True substrates are defined as sedimentary bedding planes that demonstrably existed at the sediment-water or sediment-air interface at the time of deposition, as evidenced by features such as ripple marks or trace fossils. Here we describe true substrates from the Silurian Tumblagooda Sandstone of Western Australia, which have been identified by the presence of the surficial trace fossil Psammich nites. The examples are unexpected because they have developed along erosional internal bounding surfaces within a succession of cross-bedded sandstones. However, their seemingly counterintuitive preservation can be explained with reference to recent advances in our understanding of the time-incomplete sedimentary-stratigraphic record (SSR). The preservation of true substrates seems to be an inevitable and ordinary result of deposition in environments where sedimentary stasis and spatial variability play important roles. We show that the true substrates developed during high-frequency allogenic disturbance of migrating bedforms, forcing a redistribution of the loci of sedimentation within an estuarine setting, and subsequently permitting an interval of sedimentary stasis during which the erosional bounding surfaces could be colonized. These observations provide physical evidence that supports recent contentions of how sedimentary stasis and the interplay of allogenic and autogenic processes impart a traditionally underestimated complexity to the chronostratigraphic record of geological outcrop. CHRONOSTRATIGRAPHY AND TRUE SUBSTRATES It has been recognized for over a century that unconformities and sedimentary breaks riddle Earth's stratigraphic record at a variety of scales, such that two-dimensional (2-D) stratigraphic sections are fragmentary chronicles of elapsed geological time (Barrell, 1917; Sadler, 1981; Dott, 1983). Recently, a number of largely model-driven studies have explored the previously underappreciated causes and effects of this time-deficient SSR (Miall, 2015; Paola et al., 2018). Three recurring themes are: (1) Ordinariness: The SSR preferentially records mundane rather than dramatic events (Jerolmack and Paola, 2010; Paola, 2016). (2) Sedimentary stasis: The dominant sedimentation state under which the SSR accumulated was stasis; i.e., 'neither deposition nor erosion', rather than 'either deposition or erosion' (Ganti et al., 2011; Tipper, 2015; Straub and Foreman, 2018). (3) Spatial variation: Any time gaps in one 2-D stratigraphic section of a basin fill were likely compensated by contemporaneous deposition of strata elsewhere within the same basin (

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“…The preservation of skin textures within demonstrable surface traces shows that this stratigraphic surface can be considered to be a true substrate (Davies et al, 2017;: a sedimentary bedding plane which existed at the sediment-water or sedimentair interface at the time of deposition, and which was not degraded during the deposition of the overlying sands. The preservation of delicate footprint textures on a true substrate need not be unexpected, because the distal point source of the overlying crevasse splay sands means that their deposition at a specific footprint location was not necessarily coupled with erosion .…”

Section: Footprints At the Base Of The Lee Ness Sandstonementioning

confidence: 99%

Dinosaur-landscape interactions at a diverse Early Cretaceous tracksite (Lee Ness Sandstone, Ashdown Formation, southern England)

Shillito

Davies

2019

Palaeogeography, Palaeoclimatology, Palaeoecology

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An assemblage of dinosaur footprints is reported from the Lower Cretaceous (Berriasian-Valanginian) Ashdown Formation of East Sussex, southern England. The ichnofauna is concentrated around a 2 m thick stratigraphic marker, the Lee Ness Sandstone, where recent cliff retreat has revealed 85 recognisable footprints attributable to 13 morphotypes, many of which bear high-fidelity skin impressions. The newly identified morphotypes mean that this tracksite hosts one of the most diverse dinosaur ichnoassemblages in the well-documented Mesozoic record of Britain; recording the activity of theropod, ornithopod, thyreophoran and possibly sauropod tracemakers. Most of the footprints were emplaced on a single floodplain mudstone horizon beneath a fluvial crevasse splay sandstone, where preservation was favoured by cohesive sediment and a prolonged interval of sedimentary stasis, during which trackways could be imparted. The sedimentological context of the trackways reveals evidence of interactions between dinosaurs and the riverine landscape that they inhabited; including the development of microtopographies around footprints, which impacted invertebrate burrowing activity, and evidence for dinosaur wading below the bankfull level of small meandering channels and oxbow lakes. Modern analogue suggests that the large dinosaurs may have played a significant role as zoogeomorphic engineers within the ancient floodplain setting, but the imperfect translation of sedimentary environment to sedimentary rock means that geological evidence for such is ambiguous.

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Short-Term Evolution of Primary Sedimentary Surface Textures (Microbial, Abiotic, Ichnological) on a Dry Stream Bed: Modern Observations and Ancient Implications

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 23 publications

References 27 publications

The applicability of modern tidal analogues to pre‐vegetation paralic depositional models

The applicability of modern tidal analogues to pre‐vegetation paralic depositional models

Incomplete but intricately detailed: The inevitable preservation of true substrates in a time-deficient stratigraphic record

Dinosaur-landscape interactions at a diverse Early Cretaceous tracksite (Lee Ness Sandstone, Ashdown Formation, southern England)

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