Compartimentação geomorfológica e processos deposicionais no megaleque fluvial do rio São Lourenço, Pantanal mato-grossense

doi:10.5327/z0375-75362012000500003

Cited by 7 publications

(1 citation statement)

References 7 publications

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“…This erosive intensity can alternate according to the climatic and hydropedological conditions in different epochs. However, comparing the dates with the environmental variations described by Corradini and Assine (2012) and by McGlue et al (2012), it can be observed that these profiles passed through a drier period with higher sedimentation that were favorable to concentration of ions in the soil and the formation of saline and sodic characters. Because the current climate conditions are more humid, the incision of the rivers is more accentuated and, consequently, erosion processes predominate, which are the main aspect 5000 μm 5000 μm 5000 μm 1000 μm Figure 7.…”

Section: Soil Properties and Pedogenetic Processesmentioning

confidence: 99%

Genesis and Classification of Sodic Soils in the Northern Pantanal

Oliveira

Chiapini

Nascimento

et al. 2017

Rev. Bras. Ciênc. Solo

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ABSTRACT:The simultaneous occurrence of high levels of exchangeable sodium percentage (ESP) and alkalinity in soils imposes restrictions on plant development and affects physical properties such as porosity, bulk density, permeability, and hydraulic conductivity. Although sodic soils are frequent in the flood plain of the São Lourenço River, northern Pantanal, Brazil, few studies focus on their formation and classification, especially with regard to specific processes and detailed classification into lower categorical levels by the different systems available. The aim of this study was to identify the predominant pedogenetic processes occurring in sodic soils of the flood plain of the São Lourenço River to understand their genesis and assess how taxonomic classification systems contemplate the variations in soil properties. Five profiles were selected in sites with different progressive stages of dissection from erosion (P1, P2, P3, P4, and P5). At each site, a pit was dug for morphological description of the profiles and for collecting samples for chemical, particle size, mineralogical, micromorphological, and chronological analyses. Each profile was classified according to the Soil Taxonomy, World Reference Base (WRB), and Brazilian Soil Classification System (SiBCS/ Sistema Brasileiro de Classificação de Solos). Argilluviation is the predominant process, with a localized and intense ferrolysis action in the E/Bt transition zones in profile P5. Soils showed signs of lithologic discontinuity. This makes it difficult to distinguish how much of the textural gradient is inherited from fluvial sedimentation processes and how much is the result of pedogenetic processes. In the most advanced stage of alteration, P5 had a paler color, thickening of the E horizon, and an abrupt and irregular transition entering the Bt horizon in the form of a "tongue". When passing from the most preserved to the most eroded area, ferrolysis becomes more intense in the E/Bt transition, the electrical conductivity values decrease, and the ESP values increase, suggesting the sodification process. Under Soil Taxonomy criteria, P5 was classified as Natraqualf and the other profiles were classified as Natrudalf; under the WRB, however, all profiles were classified as Solonetz. The SiBCS exhibited variation at the Order level, with P5 classified as Planossolo and the others as Luvissolo. Despite an indication of different processes at the Order level, the SiBCS does not yet contemplate the sodic character in the studied Luvissolos. We propose inclusion of the sodic character at the Great Group level, as has already occurred with other SiBCS classes.

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Section: Soil Properties and Pedogenetic Processesmentioning

confidence: 99%

Genesis and Classification of Sodic Soils in the Northern Pantanal

Oliveira

Chiapini

Nascimento

et al. 2017

Rev. Bras. Ciênc. Solo

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Geology and Geomorphology of the Pantanal Basin

Assine¹,

Merino²,

Pupim³

et al. 2015

The Handbook of Environmental Chemistry

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What is an inlier sedimentary basin? What are the main mechanisms of sedimentary infilling? How do the depositional systems behave? And last, but certainly not the least, what geological events occurred in the last million years and continue to take place in the Pantanal area today? These issues are considered in this chapter, based on available geological, geomorphological, and geochronological datasets. The Pantanal is an active sedimentary basin with numerous faults and associated earthquakes. Movements along these faults cause subsidence on blocks within the basin, generating depressions that are highly susceptible to flooding, and also create accommodation space for sediment storage. One hypothesis on the origin of the Pantanal Basin relates the processes of subsidence with tectonic activity in the Andean orogen and foreland system during the Quaternary. Alternatively, the lack of geochronological data leaves open the possibility that the basin formed much earlier, perhaps during an interval of widespread tectonism in Brazil during the Eocene. The modern Pantanal depositional tract is composed of the Paraguay River trunk system, numerous fluvial megafans and interfan floodplains, and thousands of lakes, many of them integral to the Nhecolândia landscape. The Pantanal's geomorphology is most likely the product of climatic fluctuations and environmental changes that have been occurring since the Late Pleistocene.

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Brazilian Pantanal: A Large Pristine Tropical Wetland

Assine

2015

World Geomorphological Landscapes

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The Pantanal is a Quaternary sedimentary basin located in the central-west region of Brazil. Its origin has been linked to stresses transmitted from the western margin of the South American continent into the interior of the craton. Therefore, the Pantanal is part of the Andean foreland system. It presents alluvial plain morphology with altitudes between 80 and 200 m surrounded by desiccated plateaus. Northeast-southwest-aligned faults, many associated with the Transbrasiliano Lineament, control part of the drainage network within the Pantanal Basin. The Paraguay River meanders through an extensive fluvial plain, bordering Precambrian terrains at the western edge of the basin. The Paraguay River is the main river of a depositional system characterized by fluvial megafans, among which the Taquari River megafan stands out. Since the Late Pleistocene, the Pantanal landscape has been changing in response to a climate shift from colder and drier to wetter and warmer conditions. These climate changes are recorded in the Pantanal landscape, which is marked by relict depositional landforms of varying ages formed in environmental and climatic conditions differing from the present. The thousands of Nhecolândia lakes located in the southern sector of the Taquari megafan are examples of relict landforms. These lakes are mostly freshwater lakes connected through rainwater runoff, forming wide and shallow channels (locally called "vazantes") that drain the fluvial plain during and after the wet season. In contrast, some saline lakes (locally called "salinas") remain isolated from the surface drainage and are relict landforms of a degrading landscape. The Pantanal is a large tropical wetland exhibiting mostly native vegetation, where wildlife is preserved in its natural habitats. The rivers building the fluvial megafans are prone to frequent avulsions, shifting their channels according to sediment infilling dynamics in the fluvial plain. These shifts in river courses result in considerable changes in the hydrography and geography of the flood plain. KeywordsBrazilian Pantanal Á Wetlands Á Fluvial landscape Á Changing rivers IntroductionThe Pantanal is located between latitudes 16 and 21°S; 90 % of its area is situated within the central-west region of Brazil, with the remaining area extending into Paraguay and Bolivia. The Pantanal is an inland depression within the hydrographic basin of the Upper Paraguay River, with altitudes between 80 and 190 m above sea level, and it is surrounded by plateaus carved in Paleozoic sedimentary rocks and Precambrian crystalline rocks. The Pantanal is an alluvial plain dominated by rivers showing a seasonal hydrological cycle, with extensive floods occurring between December and May. Extending over 135,000 km 2 , the Pantanal is one of the most important wetlands in the world (Por 1995; Fraser and Keddy 2005;Junk et al. 2006). It is

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Compartimentação geomorfológica e processos deposicionais no megaleque fluvial do rio São Lourenço, Pantanal mato-grossense

Cited by 7 publications

References 7 publications

Genesis and Classification of Sodic Soils in the Northern Pantanal

Genesis and Classification of Sodic Soils in the Northern Pantanal

Geology and Geomorphology of the Pantanal Basin

Brazilian Pantanal: A Large Pristine Tropical Wetland

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