@Article{LatrubesseSCMTHBA:2012:LaQuMe,
               author = "Latrubesse, Edgardo Manuel and Stevaux, Jos{\'e} C{\^a}ndido and 
                         Cremon, {\'E}dipo Henrique and May, Jan-Hendrik and Tatumi, Sonia 
                         Hatsue and Hurtado, Mart{\'{\i}}n A. and Bezada, Maximiliano and 
                         Argollo, Jaime B.",
          affiliation = "{} and {} and {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Late Quaternary megafans, fans and fluvio-aeolian interactions in 
                         the Bolivian Chaco, tropical South America",
              journal = "Palaeogeography, Palaeoclimatology, Palaeoecology",
                 year = "2012",
               volume = "356-357",
                pages = "75--88",
                month = "Oct.",
             keywords = "air mass, alluvial fan, biome, deflation, dune field, eolian 
                         deposit, fluvial deposit, orography, rainfall, subtropical region, 
                         Bolivia, Gran Chaco, South America, chaco, fluvio-aeolian, 
                         megafans, paleogeography, quaternary, tropical South America.",
             abstract = "The Chaco is a huge plain and a main biogeographic biome of South 
                         America dominated by subtropical semi-deciduous vegetation that 
                         spreads on the Andes footslope on more than 800,000km 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 28ka) 
                         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 ~1.5ka. 
                         During the Holocene, the megafans and aeolian systems didn't reach 
                         Late Pleistocene size and level of activity.",
                  doi = "10.1016/j.palaeo.2012.04.003",
                  url = "http://dx.doi.org/10.1016/j.palaeo.2012.04.003",
                 issn = "0031-0182",
                label = "lattes: 7888258901938956 3 LatrubesseSCMTHBA:2012:LaQuMe",
             language = "en",
        urlaccessdate = "30 abr. 2024"
}