Full text
| |
| Author(s): |
Andre Luiz de Souza Celarino
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Geociências |
| Defense date: | 2011-03-16 |
| Examining board members: |
Francisco Sérgio Bernardes Ladeira;
Pablo Vidal Torrado;
Ricardo Marques Coelho
|
| Advisor: | Francisco Sérgio Bernardes Ladeira |
| Abstract | |
The Mogi Guaçu river, near to Estação Ecológica de Jataí (Luis Antônio-SP), shows high sinuosity on its channel and many abandoned meaders caused by lateral migration and main course's avulsion. This situation is responsible by a specific configuration for the soils which are localized at terrace and at the river's alluvial plain. For a better understanding of the local morphopedogenesis, a profiles' sequence and some boreholes were made in order to investigate the lateral continuity of the soil horizons, and then perform chemical analysis, particle size distribution, mineralogy, micromorphology and datings.This process enabled the identification of horizons rich in organic matter which fills the lowland and the old's alluvial plain, which are developing above residual deposits of 130.000B.P, in according to the dating of one of the profiles. These horizons have different genesis. One of them, classified as histic horizon (H), developed filling an older abandoned meander, while the horizons above, compound by a sequence of humic A horizons, were deposited later on high energy river environment, at some point where it has been cut its thalweg in some meters and moved away of the alluvial plain. This horizon was buried by alluvial sediments and the preservation of organic matter was efficient, despite of showing lower amounts of organic carbon than H horizon.The mineralogy has shown that Caulinite is the predominant mineral in clay fraction, although Gibbsite and HIV also exist. HIV may be the result of neoformation, indicating an actual situation of free drainage, or, its presence is allochthounous. The micromorpholy has shown preserved redox lineament on the bottom of profile 3, porosities associated to water loss processes by surface and big granulometric differences between the profiles. One of the biggest differences refers to the grain selection's reduction of the skeleton in the direction of the slope to the alluvial plain. The molar ratios indicated gaps on 2A horizon in the P5 and P3, and between Ah and H horizons, on profile 4, showing different profile conditions of soil forming. The formation process of those horizons is linked with lateral migration of the river Mogi Guaçu and incision of its thalweg, which provides reducing conditions for the amount of organic matter, resulting in higher and lesser moments of accumulation.By datings was possible propose paleoterrace and alluvial plain formation chronology of last 130.000 years and associated soils, although, the considerations made about paleoclimate and structural factors influence aren't conclusive, due to geologic and geomorphologic dynamic of area, that is much specific (AU) | |