Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality

This study includes a thorough systematic analysis of the ichnological record in the uppermost section of the Agua de la Mula Member of the Agrio Formation (Mendoza Group) in the Neuquén Basin (Argentina). The Bajada del Agrio section represents an environment evolving from marine to marginal-marine...

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Autores principales: Fernández, D.E., Pazos, P.J.
Formato: JOUR
Materias:
Agrio formation
Argentina
Cretaceous
Ichnology
Marginal marine environment
Neuquén basin
Salinity
facies
fossil record
ichnology
marine ecosystem
marine sediment
salinity
tidal flat
Neuquen Basin
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00027014_v49_n4_p505_Fernandez
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00027014_v49_n4_p505_Fernandez2023-10-03T13:53:12Z Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality Fernández, D.E. Pazos, P.J. Agrio formation Argentina Cretaceous Ichnology Marginal marine environment Neuquén basin Salinity Cretaceous facies fossil record ichnology marine ecosystem marine sediment salinity tidal flat Argentina Neuquen Basin This study includes a thorough systematic analysis of the ichnological record in the uppermost section of the Agua de la Mula Member of the Agrio Formation (Mendoza Group) in the Neuquén Basin (Argentina). The Bajada del Agrio section represents an environment evolving from marine to marginal-marine. Five main facies were defined: (1) an oolitic-skeletal bar; (2) transgressive pelites and coquinas (biodastic conglomerates); (3) progradational coarsening-upward sandstones; (4) heterolithic deposits; and (5) heterolithic and carbonatic deposits. Fluctuating salinity and/or hypersalinity is inferred in the open tidal-flat deposits (facies 4). Sixteen ichnotaxa were identified and three types of trace fossils were described using open nomenclature because of the poor preservation of the material. Three ichnoassemblages are described. The section yielded trace fossils of callianasid decapods, palaeotaxodont bivalves, annelids and small tetrapods. Paleoenvironmental information drawn from trace fossils is coincident with sedimentologic evidence. It also highlights the current lack of accurate ichnological models for marginal marine hypersaline or fluctuating-saline environments, and suggests that sharp salinity changes in the environment not necessarily implie a decrease in ichnodiversity. Fil:Fernández, D.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Pazos, P.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00027014_v49_n4_p505_Fernandez
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Agrio formation
Argentina
Cretaceous
Ichnology
Marginal marine environment
Neuquén basin
Salinity
Cretaceous
facies
fossil record
ichnology
marine ecosystem
marine sediment
salinity
tidal flat
Argentina
Neuquen Basin
spellingShingle Agrio formation
Argentina
Cretaceous
Ichnology
Marginal marine environment
Neuquén basin
Salinity
Cretaceous
facies
fossil record
ichnology
marine ecosystem
marine sediment
salinity
tidal flat
Argentina
Neuquen Basin
Fernández, D.E.
Pazos, P.J.
Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality
topic_facet Agrio formation
Argentina
Cretaceous
Ichnology
Marginal marine environment
Neuquén basin
Salinity
Cretaceous
facies
fossil record
ichnology
marine ecosystem
marine sediment
salinity
tidal flat
Argentina
Neuquen Basin
description This study includes a thorough systematic analysis of the ichnological record in the uppermost section of the Agua de la Mula Member of the Agrio Formation (Mendoza Group) in the Neuquén Basin (Argentina). The Bajada del Agrio section represents an environment evolving from marine to marginal-marine. Five main facies were defined: (1) an oolitic-skeletal bar; (2) transgressive pelites and coquinas (biodastic conglomerates); (3) progradational coarsening-upward sandstones; (4) heterolithic deposits; and (5) heterolithic and carbonatic deposits. Fluctuating salinity and/or hypersalinity is inferred in the open tidal-flat deposits (facies 4). Sixteen ichnotaxa were identified and three types of trace fossils were described using open nomenclature because of the poor preservation of the material. Three ichnoassemblages are described. The section yielded trace fossils of callianasid decapods, palaeotaxodont bivalves, annelids and small tetrapods. Paleoenvironmental information drawn from trace fossils is coincident with sedimentologic evidence. It also highlights the current lack of accurate ichnological models for marginal marine hypersaline or fluctuating-saline environments, and suggests that sharp salinity changes in the environment not necessarily implie a decrease in ichnodiversity.
format JOUR
author Fernández, D.E.
Pazos, P.J.
author_facet Fernández, D.E.
Pazos, P.J.
author_sort Fernández, D.E.
title Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality
title_short Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality
title_full Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality
title_fullStr Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality
title_full_unstemmed Ichnology of marginal marine facies of the Agrio Formation (lower cretaceous, Neuquén basin, Argentina) at its type locality
title_sort ichnology of marginal marine facies of the agrio formation (lower cretaceous, neuquén basin, argentina) at its type locality
url http://hdl.handle.net/20.500.12110/paper_00027014_v49_n4_p505_Fernandez
work_keys_str_mv AT fernandezde ichnologyofmarginalmarinefaciesoftheagrioformationlowercretaceousneuquenbasinargentinaatitstypelocality
AT pazospj ichnologyofmarginalmarinefaciesoftheagrioformationlowercretaceousneuquenbasinargentinaatitstypelocality
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