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DOI10.1016/j.palaeo.2017.06.030
Bioerosion of a modern bedrock stream bed by insect larvae (Conecuh River; Alabama): Implications for ichnotaxonomy; continental ichnofacies; and biogeomorphology
Savrda C.E.
发表日期2019
ISSN0031-0182
起始页码3
结束页码13
卷号513
英文摘要Observations along the Conecuh River, southern Alabama, demonstrate the impact that insect larvae can have on bioerosion of freshwater aquatic bedrock substrates. Eocene siliceous claystones and sandstones exposed along the river are locally densely riddled by modern burrows produced by chironomid (midge) and trichopteran (caddisfly) larvae. Chironomid larvae produce diminutive U-shaped burrows (U width = 2–7 mm, U length = 1–4 cm, burrow diameter = 0.5–2.0 mm) generally oriented normal to bedrock surfaces. Trichopteran larvae generally produce somewhat larger (burrow depth = 2–4 cm, burrow diameter = 4–6 mm), vertical, crudely Y-shaped burrows consisting of an upper U-tube, which is extended above the substrate by agglutinated chimneys, and one or two basal subvertical shafts. Both burrow types exhibit faint scratch traces on exposed burrow margins and silk-and-sediment linings that include a thicker constructed wall or septum in interlimb areas of their U-tubes. Distribution of the two structure types is controlled by bedrock texture and induration, tracemaker propensity to occupy transiently available substrates, and other as yet unidentified factors. Chironomid and trichopteran larvae burrows in these firmgrounds resemble the ichnotaxa Arenicolites and Polykladichnus, respectively. However, differences in burrow production in soft versus firm substrates, combined with uncertainties with regard to potential modes of preservation of the modern burrows, make it difficult to establish ichnotaxonomic equivalence and raise broader questions regarding inferred behavior and ichnotaxonomy of U-form burrows in firmgrounds (e.g., Rhizocorallium). Regardless of ichnotaxonomic assignment, ichnofabrics produced by modern insect larvae in fluvial firmgrounds closely match those diagnostic of the Glossifungites ichnofacies in marine and marginal strata, and thus the scope of this ichnofacies arguably should be expanded to include comparable ichnofossil assemblages preserved in ancient continental deposits. Beyond their implications for palichnology, observations made herein underscore the need to include bedrock stream channels and their biota in integrative biogeomorphologic investigations. © 2017 Elsevier B.V.
英文关键词Chironomid larvae; Firmground; Glossifungites ichnofacies; Ichnology; Trichopteran larvae
语种英语
scopus关键词bedrock; bioerosion; burrow; claystone; Eocene; fossil assemblage; ichnofabric; ichnofacies; ichnology; insect; larva; marine environment; preservation; sandstone; stream bed; taxonomy; Alabama; Conecuh County; United States; Arenicolites; Chironomidae; Hexapoda; Rhizocorallium; Trichoptera
来源期刊Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型期刊论文
条目标识符http://gcip.llas.ac.cn/handle/2XKMVOVA/151214
作者单位Department of Geosciences, 2050 Beard-Eaves Coliseum, Auburn UniversityAL 36849, United States
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Savrda C.E.. Bioerosion of a modern bedrock stream bed by insect larvae (Conecuh River; Alabama): Implications for ichnotaxonomy; continental ichnofacies; and biogeomorphology[J],2019,513.
APA Savrda C.E..(2019).Bioerosion of a modern bedrock stream bed by insect larvae (Conecuh River; Alabama): Implications for ichnotaxonomy; continental ichnofacies; and biogeomorphology.Palaeogeography, Palaeoclimatology, Palaeoecology,513.
MLA Savrda C.E.."Bioerosion of a modern bedrock stream bed by insect larvae (Conecuh River; Alabama): Implications for ichnotaxonomy; continental ichnofacies; and biogeomorphology".Palaeogeography, Palaeoclimatology, Palaeoecology 513(2019).
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