globalchange  > 过去全球变化的重建
DOI: 10.1016/j.palaeo.2015.04.013
论文题名:
Diatom, phytolith, and pollen records from a 10Be/9Be dated lacustrine succession in the chad basin: Insight on the miocene-pliocene paleoenvironmental changes in Central Africa
作者: Novello A.; Lebatard A.-E.; Moussa A.; Barboni D.; Sylvestre F.; Bourlès D.L.; Paillès C.; Buchet G.; Decarreau A.; Duringer P.; Ghienne J.-F.; Maley J.; Mazur J.-C.; Roquin C.; Schuster M.; Vignaud P.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 430
起始页码: 85
结束页码: 103
语种: 英语
英文关键词: Climate ; Hominin ; Lake chad ; Miocene-Pliocene ; Sahara-Sahel ; Vegetation
英文摘要: A discontinuous 200m-long borehole drilled in the Bol Archipelago (13°N, Lake Chad) provided 25 samples, which were dated using the 10Be/9Be method and analyzed for their micro-biological content. The dating provided ages ranging from 6.3±0.1 to 2.6±0.1Ma, a period contemporaneous with the Pliocene fossil localities located in the current Djurab desert of Chad (16-17°N).Well-preserved diatom assemblages first occurred at 4.7 ± 0.1. Ma and were dominated by the freshwater planktonic genera Aulacoseira and Stephanodiscus until the end of the Pliocene. This supports the recurrence of lacustrine conditions at Bol during all the Pliocene. The presence of pelite and argillaceous deposits in the core before 4.7 ± 0.1 Ma, however, suggests that the lake settled earlier, at least since 6.3 ± 0.1 Ma. The abundance of Afromontane pollen taxa at 4.2 ± 0.1 Ma and the occurrence of trapeziform polylobate phytoliths throughout the sequence suggest significant vegetation inputs from the southern highlands, while the importance of kaolinite in the clay sediments indicates a water supply predominantly from the south during the Pliocene. Phytolith assemblages are all dominated by lobate grass silica short cells and by blocky and elongate types, which attest to the presence of herbaceous-dominated vegetation around Bol and/or in the southern drainage basin during the Pliocene. This result is also supported by the pollen assemblage described at 4.2 ± 0.1. Ma, which shows highest affinity for the savanna biome. Moreover, low values for the Xerophytic grass phytolith index indicate the presence of humid-loving (mesophytic and aquatic) grass communities in this vegetation. At last, significant variations in the abundance of blocky and elongate phytoliths are indicative of local alternations of fully lacustrine and marshy conditions at Bol. Particularly between 3.6 and 2.7 Ma, the abundance of silicified bulliform cells combined with the absence of diatoms support a significant lacustrine reduction at Bol favoring the increasing of local marshy vegetation. © 2015 Elsevier B.V.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68919
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作者单位: IPHEP, Institut de Paléoprimatologie, Paléontologie Humaine: Evolution et Paléoenvironnements, UMR 7262 CNRS-INEE - Université de Poitiers, 6 rue Michel Brunet, Poitiers, Cedex 9, France; Aix-Marseille Université, CNRS-IRD UM 34 CEREGE, TechnopÔle de l'Environnement Arbois-Méditerranée, BP80, Aix-en-Provence, France; Département de Paléontologie, Université de N'Djamena, N'Djamena, Chad; IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers, UMR 7285 CNRS - Université de Poitiers, 4 rue Michel Brunet - TSA 51106, Poitiers, Cedex 9, France; Institut de Physique du Globe de Strasbourg, UMR7516, CNRS - Université de Strasbourg/EOST, 1 rue Blessig, Strasbourg, Cedex, France; IRD and oDépartement Paléoenvironnements, Institut des Sciences de l'Evolution de Montpellier, UMR 5554 CNRS, Université de Montpellier II, Montpellier, Cedex 5, France

Recommended Citation:
Novello A.,Lebatard A.-E.,Moussa A.,et al. Diatom, phytolith, and pollen records from a 10Be/9Be dated lacustrine succession in the chad basin: Insight on the miocene-pliocene paleoenvironmental changes in Central Africa[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,430
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