Burrowed Stiffgrounds on Estuarine Point Bars&lt;subtitle&gt;Modern and Ancient Examples, and Criteria for their Discrimination from Firmgrounds Developed Along Omission Surfaces&lt;/subtitle&gt;

Lettley, Curtis D.; Gingras, Murray K.; Pearson, Nadine J.; Pemberton, S. George

doi:10.2110/pec.07.52.0325

Cited by 7 publications

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“…Laterally traceable firmgrounds that possess relatively homogenous, planar and distinct surfaces with robust traces are much more likely to be significant, at least stratigraphically, than heterogeneous stiffgrounds possessing less firm, more compressible substrates that have not yet underdone burial or compaction (Lettley et al . ).…”

Section: Discussionmentioning

confidence: 97%

“…Lettley et al . () indicated that the discrimination between stiffground and firmground is a significant factor in assessing the significance of a Glossifungites ichnofacies surface. Laterally traceable firmgrounds that possess relatively homogenous, planar and distinct surfaces with robust traces are much more likely to be significant, at least stratigraphically, than heterogeneous stiffgrounds possessing less firm, more compressible substrates that have not yet underdone burial or compaction (Lettley et al .…”

Section: Discussionmentioning

confidence: 99%

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Spatial, temporal and palaeoecological significance of exhumed firmgrounds and other associated substrate types in Netarts Bay, Oregon, USA

Hodgson

Gingras

Zonneveld

2015

LET

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-P. 2015: Spatial, temporal and palaeoecological significance of exhumed firmgrounds and other associated substrate types in Netarts Bay, Oregon, USA. Lethaia, Vol. 48, Important palaeoecologic and stratigraphic information can be obtained by observing trace assemblages within various substrate types in a modern intertidal marine environment. Overall, there has been a lack of studies conducted concerning quantitative firmness measurements on firmground, stiffground and softground substrates in a modern intertidal setting, and the combined palaeoecological and stratigraphic significance of such substrates. This study assesses the sedimentologic and neoichnologic nature of associated peaty-clay firmground, silty-sand firmground, woodground, stiffground and softground substrates in Netarts Bay, Oregon, USA, to gain a more complete understanding of the potential palaeoecologic and stratigraphic utility of these substrates in an intertidal setting. A north-south-oriented transect was conducted along the eastern margin of Netarts Bay where descriptions of surface and sub-surface biogenic and sedimentary structures were conducted via trenching, boxcoring and epoxy resin casting with results recorded and photographed. A sample of 18 different organisms creating biogenic structures were obtained, stored in glass jars and preserved with an 80% ethyl alcohol solution. Quantitative substrate firmness measurements were conducted on four of the five different substrate types using a modified Brinell firmness test. In Netarts Bay, firmground substrates and associated trace assemblages displaying larger, more robust, vertical traces likely have a higher preservation potential compared with stiffground to softground substrates that have trace assemblages composed of smaller traces that tend to grade into a horizontal position. Firmground substrate in Netarts Bay display more homogenous and firmer profiles (1.28 9 10 6 Pa to 2.77 9 10 6 Pa) than those of more heterogeneous stiffground (1.37 9 10 5 Pa to 2.44 9 10 6 Pa) and softground (8.60 9 10 4 Pa to 3.73 9 10 5 Pa) substrate. The relatively planar Pleistocene-aged firmground substrates and associated in situ woodground substrates at Netarts Bay were found to be laterally extensive and mappable stratigraphically significant surfaces. This is in contrast to the highly variable, non-significant, erosionally derived stiffground and bay-derived softground substrates that are neither extensive nor mappable. Trace assemblages in the peaty-clay and silty-sand firmgrounds studied were representative of a Glossifungites ichnofacies assemblage while associated in situ woodground trace assemblages comprised localized Studying the trace-making behaviour of modern organisms in relation to various physico-chemical stressors is important to aid in furthering our understanding of similar biogenically created structures in the rock record. Various physico-chemical stresses include, but are not limited to; substrate consistency, sediment cohesiveness, food-resource availability, hydraulic energy...

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Spatial, temporal and palaeoecological significance of exhumed firmgrounds and other associated substrate types in Netarts Bay, Oregon, USA

Hodgson

Gingras

Zonneveld

2015

LET

Self Cite

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Sedimentary deposits and bioturbation in an Early Cretaceous subarctic stormy greenhouse shelf environment

2023

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This study of the Aptian lower part of the Carolinefjellet Formation in Svalbard, Norwegian high Arctic, is based on well cores and outcrop section in the Adventdalen area of Spitsbergen and reports on the deposits and bioturbation structures of an ancient subpolar marine shelf from a well-known period of global greenhouse climate. The study documents the sedimentation conditions and benthic fauna activity on a warm-water aggrading shelf subject to harsh Arctic wave climate and eurybatic base-level changes, with episodic bottom incursions of cold polar water. Lithofacies associations and 38 observed ichnotaxa represent subenvironments ranging from offshore to lower shoreface and hosting the Cruziana ichnofacies in its distal to proximal expression, with a brief mid-Aptian encroachment of middle shoreface zone with a distal expression of the Skolithos ichnofacies. The ichnofacies are variously impoverished compared to their archetypes. The sediment bioturbation intensity varies, but similar lithofacies associations show a comparable intensity throughout the stratigraphic succession, which indicates an ichnofauna ecology controlled by the seafloor hydraulic regime and oxygenation, and thus mainly by the wave climate and relative sea-level changes. Sandstone tempestites indicate high-frequency storms, commonly exceeding the magnitude of largest modern hurricane events. The study confirms that a change in global climate mode, such as the Early Cretaceous warming, entails extreme weather conditions.

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Ichnology of tidal ravinement omission surfaces in siliciclastic transgressive deposits from the Puesto El Moro formation (Upper Cretaceous), Southern Patagonia, Argentina

Richiano

Paz

Varela³

et al. 2023

Ichnos

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Burrowed Stiffgrounds on Estuarine Point Bars<subtitle>Modern and Ancient Examples, and Criteria for their Discrimination from Firmgrounds Developed Along Omission Surfaces</subtitle>

Cited by 7 publications

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Spatial, temporal and palaeoecological significance of exhumed firmgrounds and other associated substrate types in Netarts Bay, Oregon, USA

Spatial, temporal and palaeoecological significance of exhumed firmgrounds and other associated substrate types in Netarts Bay, Oregon, USA

Sedimentary deposits and bioturbation in an Early Cretaceous subarctic stormy greenhouse shelf environment

Ichnology of tidal ravinement omission surfaces in siliciclastic transgressive deposits from the Puesto El Moro formation (Upper Cretaceous), Southern Patagonia, Argentina

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