Processes and Environments of the Brazilian Quaternary

Bigarella, João José; Mousinho, Maria Regina; Silvia, Jorge Xavier da; Processes,

doi:10.2307/j.ctt1w6tb9v.27

Cited by 16 publications

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“…In southeastern Brazil, the deposition of colluvium has been attributed to concentrated rainfall and open vegetation cover, which characterized the wet–dry transitions of late Quaternary climates (Bigarella et al . ; Meis & Moura ; Modenesi ). In eastern South African badlands, Clarke et al .…”

Section: Discussionmentioning

confidence: 99%

LateQuaternary colluvial deposits in theBocainaPlateau, southeasternBrazil highlands: age and palaeoenvironmental consequences

Hiruma

Modenesi-Gauttieri

Riccomini

2012

Boreas

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Despite the generalized occurrence of colluvial deposits in the humid tropical areas of southeastern Brazil, regional correlation is difficult because the deposits are discontinuous, and chronological data are very scarce and scattered. For the first time, colluvial deposits in the Bocaina Plateau are described, including 18 radiocarbon ages from 12 profiles. The plateau is located on the eastern flank of the Continental Rift of Southeastern Brazil and is the highest part of the Serra do Mar, with elevations up to 2000 m above sea level. Because the Bocaina Plateau is part of the summit surfaces of southeastern Brazil, it was subjected to specific climatic conditions during the Quaternary. Colluvial deposits on the lower hillslopes and edges of amphitheatres can show complex sequences with up to three intercalated dark humic horizons, corresponding to Late Pleistocene and Holocene phases of morphodynamic activity and pedogenesis. Ages of palaeosols vary from 650±50 a BP to 36 880±980 a BP. Landforms and colluvia on the Bocaina Plateau are very similar to those found on the opposite flank of the continental rift, on the Campos do Jordão Plateau. Ages of buried soils point to similar soil formation and colluviation episodes in the two plateaus. As in Campos do Jordão, the succession of erosive, depositional and pedogenetic processes on the altos campos hillslopes is probably related to late Quaternary climate changes.

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Section: Discussionmentioning

confidence: 99%

LateQuaternary colluvial deposits in theBocainaPlateau, southeasternBrazil highlands: age and palaeoenvironmental consequences

Hiruma

Modenesi-Gauttieri

Riccomini

2012

Boreas

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“…comm. }), resulting in a distinct – albeit hypothetical – temporal rotation of geomorphological processes (Bigarella et al ., 1965, 1991; Clapperton, 1993). According to this line of reasoning, interglacial periods supported warmer, more humid climatic conditions.…”

Section: Geology and Palaeoclimatologymentioning

confidence: 99%

Brazilian Páramos I. An introduction to the physical environment and vegetation of the campos de altitude

Safford

1999

Journal of Biogeography

258

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Summary Aim The campos de altitude are a series of cool‐humid, grass‐dominated formations restricted to the highest summits of the southeastern Brazilian Highlands. Relatively little is known of the ecology, biogeography, or developmental history of this archipelago of mountaintop formations. This contribution presents an overview of our present state of knowledge with respect to the past and present physical environment and vegetation of the campos de altitude. The aim is (1) to introduce an international audience to the natural history of these diminutive yet important ecosystems, and (2) to provide the background for a series of forthcoming contributions that will treat the ecology of the campos de altitude and explore physical and biotic relationships between these ‘Brazilian páramos’ and similar formations in the high mountains of equatorial South and Central America. Location Beginning at altitudes of 1800–2000 m, the campos de altitude are found atop the highest summits of the main ranges of the southeastern Brazilian Highlands, between the states of Santa Catarina and Minas Gerais/Espírito Santo. Methods Drawing upon both original data and previously published results, this contribution reviews what we presently know about the physical environment and vegetation of the campos de altitude, in the context of geographic setting, geology, palaeoclimatology and palaeobotany, modern climate, modern vegetation, and conservation. Results and main conclusions Uplift of the southeastern Brazilian ranges to altitudes high enough to support orographic grasslands may have occurred as early as the middle‐ to late‐Tertiary; pollen records show that campos de altitude have been extant on southeastern summits at least since the Late Pleistocene. The present‐day climate of the campos de altitude is cool and (per)humid, but patterns of rainfall, temperature, and frost are distinctly seasonal. Although the flora of the campos de altitude is highly diverse and characterized by a high degree of endemism, the campos de altitude maintain strong floristic similarities to equatorial alpine formations of the Andean and Central American Cordillera; these similarities also extend to climate, soils, and vegetation physiognomy. Anthropogenic fires and grazing are widespread in the campos de altitude and probably contribute significantly to the modern structure of vegetation communities.

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“…Os geólogos americanos Damuth e Fairbridge (1970) apresentam, em um trabalho que serve de base para as discussões a respeito das condições climáticas no Brasil durante o Período Quaternário, principalmente no Pleistoceno, fundamentos para explicar as mudanças nas circulações atmosféricas e correntes oceânicas. Eles também se basearam em diversos estudos para a mesma área, principalmente em Bigarella e Andrade (1965) e Bigarella et al (1965), os quais apresentam evidências das variações climáticas nas formas de relevo das regiões consideradas.…”

Section: Introductionunclassified

Novas Informações Sobre Geocronologia Em Níveis De Baixo Terraço Fluvial Do Rio Mogi Guaçu, Sp, Brasil

Storani

Filho

2015

Rev. Bras. Geomorfol.

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Este trabalho visa complementar estudo inicialmente realizado por Perez Filho et al. (1980) em terraços fl uviais do Rio Mogi Guaçu, na área da Fazenda Campininha, no município paulista de Mogi Guaçu. Foram coletadas amostras de coberturas superfi ciais que recobrem três níveis de terraços, além de amostra em pedimento adjacente. Tais amostras foram submetidas à datação absoluta através do método de Luminescência Opticamente Estimulada (LOE), que determina o período da última exposição do material sedimentar à luz do sol. Os resultados das datações apontam diferentes idades do material superfi cial em cada um dos três diferentes níveis de terraço do perfi l, sendo o nível mais distante do rio e com maior altitude, mais velho (aproximadamente 1.900 anos), o nível denominado II, intermediário, mais novo que o superior (aproximadamente 1.150 anos) e o nível III, mais próximo ao canal fl uvial, o mais recente (aproximadamente 630 anos). A cobertura do pedimento é datado com aproximadamente 3.650 anos. Esses resultados indicam a possibilidade de existência de oscilações climáticas no período pré-atual, sendo que períodos mais secos (possivelmente há 1.900, 1.150 e 630 anos) permitiriam o desenvolvimento dos níveis de terraço, com deposição de material sedimentar arenoso, enquanto que períodos mais úmidos intermediários poderiam ter causado entalhamento do canal em distintos momentos, com diferenciação de tais níveis.

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Processes and Environments of the Brazilian Quaternary

Cited by 16 publications

References 0 publications

LateQuaternary colluvial deposits in theBocainaPlateau, southeasternBrazil highlands: age and palaeoenvironmental consequences

LateQuaternary colluvial deposits in theBocainaPlateau, southeasternBrazil highlands: age and palaeoenvironmental consequences

Brazilian Páramos I. An introduction to the physical environment and vegetation of the campos de altitude

Novas Informações Sobre Geocronologia Em Níveis De Baixo Terraço Fluvial Do Rio Mogi Guaçu, Sp, Brasil

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