Arid
DOI10.1016/j.palaeo.2012.04.003
Late Quaternary megafans, fans and fluvio-aeolian interactions in the Bolivian Chaco, Tropical South America
Latrubesse, Edgardo M.1; Stevaux, Jose C.2; Cremon, Edipo H.3; May, Jan-Hendrik4; Tatumi, Sonia H.5; Hurtado, Martin A.6; Bezada, Maximiliano7; Argollo, Jaime B.8
通讯作者Latrubesse, Edgardo M.
来源期刊PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
ISSN0031-0182
出版年2012
卷号356页码:75-88
英文摘要

The Chaco is a huge plain and a main biogeographic biome of South America dominated by subtropical semideciduous vegetation that spreads on the Andes footslope on more than 800,000 km(2) through Bolivia, Argentina and Paraguay. The climate is tropical wet-dry and the South American Summer Monsoon (SASM) leads to intensive convective rainfall during the summer season. Some of the world’s largest river-fans such as the Parapeti and Grande rivers megafans developed in the Bolivian Chaco. Our research was based on morpho-sedimentary information and sustained by 25 OSL dating of fluvial and aeolian sediments. We demonstrate that these megafans are bigger than previously postulated by some authors. Morphostratigraphic analysis, geochronological data and regional correlations suggest that the Chaco megafans and large piedmont fans were generated and reached maximum development during the middle pleniglacial and early pleniglacial (ca. 60 to 28 ka) because of the presence of colder and more seasonal conditions (dry-wet intense contrasting seasons) than those existing today in the Amazon and the Bolivian plains. We suggest that a main mechanism triggering the megafan development was the presence of an intense monsoonal effect on the Eastern flank of the Andes that enhanced rainfall by orographic excitation during MIS 3 and the early part of MIS 2 that produced an increase in discharge and sediment supply. Concomitantly to fluvial processes the deflation of fluvial belts occurred and big sand dune fields developed by winds blowing out from North to South following the same pattern the South American lower level jet follows presently. Maximum aridity was reached during MIS 2 with the deposition of loess deposits on the piedmont areas and megafan surfaces, the continuous generation of aeolian dunes and a remarkable decrease in the fluvial activity. Cold air mass related to the polar advection (friagens or surazos) probably affected the area with more intensity and frequency. The Lateglacial was also arid but probably less extreme than the LGM. During a good part of the Holocene the climatic conditions were still arid to semiarid but became more similar to the present sub-humid climate since similar to 1.5 ka. During the Holocene, the megafans and aeolian systems didn’t reach Late Pleistocene size and level of activity. (c) 2012 Elsevier B.V. All rights reserved.


英文关键词Chaco Megafans Quaternary Fluvio-aeolian Paleogeography Tropical South America
类型Article
语种英语
国家USA ; Brazil ; Australia ; Argentina ; Venezuela ; Bolivia
收录类别SCI-E
WOS记录号WOS:000309319300007
WOS关键词FORELAND BASIN SYSTEM ; CENTRAL ANDES ; LANDSCAPE EVOLUTION ; DYNAMICS ; CLIMATE ; RIVER ; VEGETATION ; HOLOCENE ; AMAZON ; CIRCULATION
WOS类目Geography, Physical ; Geosciences, Multidisciplinary ; Paleontology
WOS研究方向Physical Geography ; Geology ; Paleontology
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/174316
作者单位1.Univ Texas Austin, Dept Geog & Environm, Austin, TX 78712 USA;
2.Univ Estadual Maringa, GEMA Dept Geog, BR-87020900 Maringa, Parana, Brazil;
3.Natl Inst Space Res INPE, Remote Sensing Div DSR, BR-12227010 Sao Jose Dos Campos, SP, Brazil;
4.Univ Wollongong, Sch Earth & Environm Sci, Wollongong, NSW 2500, Australia;
5.Univ Nacl Estadual Sao Paulo, Fac Tecnol, FATEC, Lab Vidros & Datacoes, BR-01124060 Sao Paulo, Brazil;
6.Univ Nacl La Plata, Inst Geomorphol & Soils, RA-1900 La Plata, Argentina;
7.Univ Pedag El Liberrador, Dept Geosci, Caracas, Venezuela;
8.Univ Mayor San Andres, Dept Geol, La Paz, Bolivia
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GB/T 7714
Latrubesse, Edgardo M.,Stevaux, Jose C.,Cremon, Edipo H.,et al. Late Quaternary megafans, fans and fluvio-aeolian interactions in the Bolivian Chaco, Tropical South America[J],2012,356:75-88.
APA Latrubesse, Edgardo M..,Stevaux, Jose C..,Cremon, Edipo H..,May, Jan-Hendrik.,Tatumi, Sonia H..,...&Argollo, Jaime B..(2012).Late Quaternary megafans, fans and fluvio-aeolian interactions in the Bolivian Chaco, Tropical South America.PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY,356,75-88.
MLA Latrubesse, Edgardo M.,et al."Late Quaternary megafans, fans and fluvio-aeolian interactions in the Bolivian Chaco, Tropical South America".PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 356(2012):75-88.
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