气候变化领域集成服务门户(CCPortal): Origin of paleovalleys on the Rio Grande do Sul Shield (Brazil): Implications for the extent of late Paleozoic glaciation in west-central Gondwana

CCPortal

DOI	10.1016/j.palaeo.2018.04.013
	Origin of paleovalleys on the Rio Grande do Sul Shield (Brazil): Implications for the extent of late Paleozoic glaciation in west-central Gondwana
	Fedorchuk N.D.; Isbell J.L.; Griffis N.P.; Montañez I.P.; Vesely F.F.; Iannuzzi R.; Mundil R.; Yin Q.-Z.; Pauls K.N.; Rosa E.L.M.
发表日期	2019
ISSN	0031-0182
卷号	531
英文摘要	The location, longevity, and geographic extent of late Paleozoic ice centers in west-central Gondwana remain ambiguous. Paleovalleys on the Rio Grande do Sul Shield of southernmost Brazil have previously been interpreted as fjords carved by outlet glaciers that originated in Africa and emptied into the Paraná Basin (Brazil). In this study, the sedimentology, stratigraphy, and provenance of sediments infilling two such paleovalleys (the Mariana Pimentel and Leão paleovalleys) were examined in order to test the hypothesis that an ice center over present day Namibia drained across southernmost Brazil during the Carboniferous and Permian. Contrary to previous findings, the facies assemblage from within the paleovalleys is inconsistent with a fjord setting and no clear evidence for glaciation was observed. The facies show a transition from a non-glacial lacustrine/estuarine environment, to a fluvial-dominated setting, and finally to a restricted marine/estuarine environment. Detrital zircon results present a single population of Neoproterozoic ages (c. 800–550 Ma) from the paleovalley fill that matches the ages of underlying igneous and metamorphic basement (Dom Feliciano Belt) and is incongruent with African sources that contain abundant older (Mesoproterozoic, Paleoproterozoic, and Archean) zircons. Furthermore, results suggest that the formation of the paleovalleys and the deposition of their fill were controlled by the reactivation of Neoproterozoic basement structures during the Carboniferous and Permian. The lack of evidence for glaciation in these paleovalleys highlights the need for detailed studies of supposed late Paleozoic glacial deposits. These results are supportive of the hypothesis that well-established glacial sediments on the Rio Grande do Sul Shield (southern margin of the Paraná Basin) may be the product of a separate lobe extending north across Uruguay, rather than a single, massive ice sheet draining west from Africa. © 2018 Elsevier B.V.
英文关键词	Detrital zircon geochronology; Itararé Group; Late Paleozoic ice age; Paraná Basin; Pull-apart basin; Rio Bonito Formation
语种	英语
scopus关键词	Carboniferous; continental lithosphere; detrital deposit; estuarine environment; facies analysis; geochronology; glacial deposit; Gondwana; ice sheet; lacustrine deposit; late glacial; lithostratigraphy; metamorphic facies; Paleozoic; sediment transport; valley; zircon; Brazil; Dom Feliciano Belt; Namibia; Parana Basin; Rio Grande do Sul; Uruguay; Katsuwonus pelamis
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/150879
作者单位	Department of Geosciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, United States; Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA 95616, United States; Department de Geologia, Universidade Federal do Paraná, Caixa Postal 19001, Curitiba, PR CEP 81531-980, Brazil; Centro de Investigações do Gondwana, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91.509-900, Brazil; Berkeley Geochronology Center, Berkeley, CA 94709, United States
推荐引用方式 GB/T 7714	Fedorchuk N.D.,Isbell J.L.,Griffis N.P.,et al. Origin of paleovalleys on the Rio Grande do Sul Shield (Brazil): Implications for the extent of late Paleozoic glaciation in west-central Gondwana[J],2019,531.
APA	Fedorchuk N.D..,Isbell J.L..,Griffis N.P..,Montañez I.P..,Vesely F.F..,...&Rosa E.L.M..(2019).Origin of paleovalleys on the Rio Grande do Sul Shield (Brazil): Implications for the extent of late Paleozoic glaciation in west-central Gondwana.Palaeogeography, Palaeoclimatology, Palaeoecology,531.
MLA	Fedorchuk N.D.,et al."Origin of paleovalleys on the Rio Grande do Sul Shield (Brazil): Implications for the extent of late Paleozoic glaciation in west-central Gondwana".Palaeogeography, Palaeoclimatology, Palaeoecology 531(2019).