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dc.contributor.author
Isbell, John L.  
dc.contributor.author
Fedorchuk, Nicholas D.  
dc.contributor.author
Rosa, Eduardo L.M.  
dc.contributor.author
Goso, César  
dc.contributor.author
Alonso Muruaga, Pablo Joaquin  
dc.date.available
2024-02-22T12:35:25Z  
dc.date.issued
2023-05  
dc.identifier.citation
Isbell, John L.; Fedorchuk, Nicholas D.; Rosa, Eduardo L.M.; Goso, César; Alonso Muruaga, Pablo Joaquin; Reassessing a glacial landscape developed during terminal glaciation of the Late Paleozoic Ice Age in Uruguay; Elsevier Science; Sedimentary Geology; 451; 5-2023; 1-21  
dc.identifier.issn
0037-0738  
dc.identifier.uri
http://hdl.handle.net/11336/228006  
dc.description.abstract
Whalebacks, roche moutonnées, and S-forms carved on Ediacaran granitoids near Cerro de las Cuentas, Uruguay, along with overlying diamictites, siltstones, and sandstones displaying soft-sediment grooved and striated surfaces in the Pennsylvanian San Gregorio Formation, record the glacial to post-glacial transition in the linked Norte, southern Paraná and Chaco-Paraná basins of Uruguay, Brazil, and Argentina respectively. Early authors reported these features resulted from subglacial abrasion and deposition as lodgement tills and glaciotectonites. Our re-examination reveals a nuanced setting with changing ice thicknesses, subglacial kinematics, and ice proximal glaciomarine dynamics associated with advance and retreat of an ice stream, or multiple advances of the Uruguayan Ice lobe, during glaciation of the Late Paleozoic Ice Age (LPIA) in these basins. The preserved landforms indicate temperate glacial conditions. Whalebacks formed under 1.6 to 2.5 km-thick ice and likely formed when the lobe extended across the Uruguayan and Rio Grande do Sul shields into the adjacent Paraná Basin. Previously unidentified m-scale roches moutonnées cut into one whaleback developed under thinner ice where reduced basal pressure allowed for the opening of air and water-filled cavities, thus facilitating quarrying on the lee side of basement bumps. S-forms provide additional evidence for the occurrence of subglacial waters, indicating that the basal ice was at or above its pressure melting point. The lower meter of the overlying strata consists of interstratified trace fossil-bearing, laminated siltstones; thin-bedded diamictites; and current-rippled sandstones. Trace fossils belonging to the Mermia ichnofacies within the basal siltstones, as well as acritarchs in the overlying siltstones, suggest that these sediments were deposited in ice-proximal subaqueous settings with contributions from meltwater discharge. Graded siltstone laminae suggest settling from suspension likely from meltwater plumes, while thin-bedded diamictites were deposited either as debris flows or as two-component sedimentation with fines settling from suspension and coarser particles introduce as iceberg-rafted dropstones. Current-rippled sandstones indicate the occurrence of underflow currents. Soft-sediment troughs, grooves, and striations cutting these sediments display curved and sinuous paths with some features oriented perpendicular, and one oriented opposite to the overall trend. They contain marginal and terminal berms typical of iceberg scour marks suggesting transit across the area by icebergs calving from a tidewater ice front located to the SE.  
dc.format
application/pdf  
dc.language.iso
eng  
dc.publisher
Elsevier Science  
dc.rights
info:eu-repo/semantics/restrictedAccess  
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/  
dc.subject
ICEBERG KEEL MARKS  
dc.subject
LATE PALEOZOIC ICE AGE  
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ROCHE MOUTONNÉES  
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SAN GREGORIO FM  
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URUGUAYAN ICE LOBE  
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WHALEBACKS  
dc.subject.classification
Geología  
dc.subject.classification
Ciencias de la Tierra y relacionadas con el Medio Ambiente  
dc.subject.classification
CIENCIAS NATURALES Y EXACTAS  
dc.title
Reassessing a glacial landscape developed during terminal glaciation of the Late Paleozoic Ice Age in Uruguay  
dc.type
info:eu-repo/semantics/article  
dc.type
info:ar-repo/semantics/artículo  
dc.type
info:eu-repo/semantics/publishedVersion  
dc.date.updated
2024-02-22T11:34:45Z  
dc.journal.volume
451  
dc.journal.pagination
1-21  
dc.journal.pais
Países Bajos  
dc.journal.ciudad
Amsterdam  
dc.description.fil
Fil: Isbell, John L.. University of Wisconsin; Estados Unidos  
dc.description.fil
Fil: Fedorchuk, Nicholas D.. University of Wisconsin; Estados Unidos  
dc.description.fil
Fil: Rosa, Eduardo L.M.. University of Wisconsin; Estados Unidos  
dc.description.fil
Fil: Goso, César. Universidad de la República; Uruguay  
dc.description.fil
Fil: Alonso Muruaga, Pablo Joaquin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina  
dc.journal.title
Sedimentary Geology  
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/https://doi.org/10.1016/j.sedgeo.2023.106399