Holocene environmental changes in Carajás Region (Pará, Brazil) recorded by lacustrine deposits

Cordeiro, R. C.; Turcq, Bruno; Suguío, Kenitiro; Ribeiro, Carlos; Silva, Arlei O.; Siffedine, A.; Martin, Len

doi:10.1080/03680770.1995.11900830

Cited by 18 publications

(26 citation statements)

References 6 publications

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“…Corvoheteromeyenia australis, which is now restricted to southern South America, stands out as an indicator of colder and wetter weather. Accordingly, the data suggest that polar incursions originating in Antarctica were common during the late Pleistocene and may have played a notable role in the humidity of central Brazil during the period > 51,780 ± 400 14 C yr BP until the beginning of the LGM, when drier conditions began to predominate. Corvomeyenia thumi is again confirmed as a sponge species indicator of environments subjected to marked seasonal droughts.…”

Section: Final Remarksmentioning

confidence: 84%

“…The TL resulted in an age of 34,700 ± 5000 yr BP, whereas that obtained using OSL was 27,500 ± 4000 yr BP. Radiocarbon dating of the basal-most layer (Layer # 5 from Section 1) indicated an age of more than 53,780 years 14 C yr BP for a fragment of fossil wood and 51,780 ± 400 14 C yr BP for a fern frond [32]. In addition to these, in layer subsequent to the base (Layer # 2 from Section 2), radiocarbon dating of an angiosperm leaf obtained an age from 48,333 ± 400 years 14 C yr BP [32] (Figure 1 and Figure 2).…”

Section: Study Areamentioning

confidence: 99%

“…Phase I, which was older than 51,780 14 C yr BP [32], was formed during high levels of precipitation, as indicated by the diamictites and also by the conglomerates, favouring flows of unselected sediments resulting from the erosion of the dome and that accumulated in the areas with less steep slopes (Figure 8(a)). Machado and colleagues [34] demonstrated that a similar process is occurring in the dome of the Serra Negra, which exhibits a centripetal drainage system that accumulates in the centre.…”

Section: Phases I and Iimentioning

confidence: 99%

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Late Pleistocene Climatic Changes in Central Brazil Indicated by Freshwater Sponges

Machado¹,

Volkmer‐Ribeiro²,

Iannuzzi³

2014

IJG

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The Cemitério Palaeolake deposit in Catalão, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14 C yr B.P. The unprecedented presence of spongillite and diatomite layers in this deposit was investigated using spicules of continental sponges as proxy data for environmental and climate reconstruction, which was relatively extensive for the ages examined. From the analysis of the sedimentary features and the associations of spicules preserved in the deposit, it was possible to reconstruct the evolution of the limnic system. Five developmental stages were thus identified, corresponding to the installation (lotic and erosion phase), establishment and development of the lake and its colmatation, the latter correlating to the Last Glacial Maximum (LGM). Moreover, based on the ecological requirements of the sponge species identified in the deposit, it was possible to infer the likely weather patterns related to respective phases of the lake. The presence of the sponge species Corvoheteromeyenia australis, presently recorded only from southern South America, indicated that polar incursions originating from the Antarctic were frequent during the last glacial period and might have played a notable role in what is now central Brazil. However, for a short time, drier and hotter weather conditions might have predominated, as suggested by the presence of the species Corvomeyenia thumi.

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Section: Final Remarksmentioning

confidence: 84%

Section: Study Areamentioning

confidence: 99%

Section: Phases I and Iimentioning

confidence: 99%

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Late Pleistocene Climatic Changes in Central Brazil Indicated by Freshwater Sponges

Machado¹,

Volkmer‐Ribeiro²,

Iannuzzi³

2014

IJG

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“…The observed increase in mercury deposition rate after the LGM, may therefore be linked to drier periods and a higher frequency of forest fires, which release larger amounts of mercury from the biomass and the soils. Evidence for an increased frequency of forest fires comes from charcoal deposits in soils (Pessenda et al 1998a(Pessenda et al , 1998b and sediments (Cordeiro 1995;Cordeiro et al 1997;Lacerda et al 1999;Turcq et al 1998). In the clastic event about 18,000 years ago, mercury concentrations were highly variable, but the average value of 210 ± 160 ng g −1 is similar to the pre-LGM value of 233 ± 130 ng g −1 (Table 2).…”

Section: Resultsmentioning

confidence: 99%

Chronology of the Atmospheric Mercury in Lagoa da Pata Basin, Upper Rio Negro Region of Brazilian Amazon

et al. 2001

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ABSTRACT. We present prehistoric mercury accumulation rates in a dated sediment core from Lagoa da Pata, a remote lake in São Gabriel da Cachoeira, northern Amazon. The sediment samples were subdivided for mercury and radiocarbon analyses. A group of 18 samples have been prepared at ANU for 14 C dating by accelerator mass spectrometry (AMS). The dating results show a good correlation with depth in the core, down to 41,500 BP. Three distinct sections are clearly identified in the core. They consist of upper and lower organic-rich layers, separated by an inorganic layer which represents a short period of rapid accumulation around 18 ka BP. The mercury accumulation rate is found to be larger in the upper layer (18 ka to present) than in the lower one (41 ka to 25 ka), by a factor of three. The larger accumulation rate of mercury is probably associated with warmer temperatures and a higher frequency of forest fires during the Holocene.

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“…O aparecimento dos campos, indicativo de períodos mais secos, ocorreu provavelmente entre 60.000-40.000 anos AP, 23.000-11.000 anos AP e 7.500-3.500 anos AP (Sifeddine et al, 1994). Nesta última fase observaram-se restos de vegetais carbonizados, indicando a ocorrência de incêndios freqüentes na região (Turcq et al, 1993, Cordeiro et al, 1997, Elias et al, 2001.…”

Section: Introductionunclassified

Dinâmica do ecótono floresta-campo no sul do estado do Amazonas no Holoceno, através de estudos isotópicos e fitossociológicos

et al. 2007

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ResumoCom o emprego dos isótopos do carbono ( 12 C, 13 C, 14 C) da matéria orgânica do solo (MOS) e das plantas, é apresentado um estudo comparativo entre perfis orgânicos de solos formados em depressões de áreas cobertas por ecossistemas de campos e florestas ao sul do estado do Amazonas, visando o entendimento da dinâmica da paleovegetação. A dinâmica da vegetação atual na região foi avaliada utilizando-se estudos fitossociológicos e caracterizações botânica e isotópica (δ 13 C) das espécies de plantas presentes em duas bordas floresta-campo. Teores de carbono orgânico total foram superiores nas camadas superficiais no campo, quando comparados com a floresta. Dados de δ 13 C associados à cronologia do 14 C indicaram predomínio de plantas C 3 no início do Holoceno em ambos os ecótonos. Entre aproximadamente 7.000-3.000 anos AP verificou-se a influência crescente de plantas C 4 , indicando regressão da floresta com possível presença de um clima mais seco. A partir de aproximadamente 3.000 anos AP os dados sugeriram expansão da floresta provavelmente relacionada ao retorno a um clima mais úmido. A presença de algumas espécies características da borda, como a Sclerolobium paniculatum e Himatanthus sucuuba, nos campos, sugere o atual avanço da floresta sobre os mesmos. Estas espécies estariam sendo as bioindicadoras desse avanço. PALAVRAs-CHAVeIsótopos do carbono, Dinâmica de vegetação, Holoceno, Fitossociologia, Amazônia. Vegetation dynamics during the Holocene in a forest-savanna transition, Southern Amazon Basin, based on isotope and phytosociological studiesAbstRACt This paper presents a comparative study between organic soil horizons formed in depressions located at the forest/savanna boundary in the Southern Amazon Basin. The influence of the paleovegetation dynamics, based on carbon isotope ( 12 C, 13 C and 14 C) data of soil organic matter (SOM) and plants was evaluated, as well as the present vegetation dynamics, inferred from the modern vegetation structure, composition and phytosociology. The uppermost soil horizon in savanna showed higher total carbon content than in forest. 13 C and 14 C data from soil samples indicated a predominance of C 3 plants in the early Holocene. About 7000 to 3000 14 C yr BP the influence of C 4 plants increased, indicating savanna expansion probably related to a drier climate in the region. Since approximately 3000 14 C yr BP, the carbon isotope data suggest the expansion of forest probably due to a wetter climate. The presence of typical boundary plant species (Sclerolobium paniculatum and Himatanthus sucuuba) in the savanna also suggested present forest expansion.

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Holocene environmental changes in Carajás Region (Pará, Brazil) recorded by lacustrine deposits

Cited by 18 publications

References 6 publications

Late Pleistocene Climatic Changes in Central Brazil Indicated by Freshwater Sponges

Late Pleistocene Climatic Changes in Central Brazil Indicated by Freshwater Sponges

Chronology of the Atmospheric Mercury in Lagoa da Pata Basin, Upper Rio Negro Region of Brazilian Amazon

Dinâmica do ecótono floresta-campo no sul do estado do Amazonas no Holoceno, através de estudos isotópicos e fitossociológicos

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