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| Author(s): |
Maria Carolina da Cruz Miranda
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Geociências (IG/BT) |
| Defense date: | 2010-04-05 |
| Examining board members: |
Dilce de Fátima Rossetti;
Marcelo Cancela Lisboa Cohen;
Paulo Cesar Fonseca Giannini;
Luiz Carlos Ruiz Pessenda;
Claudio Riccomini
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| Advisor: | Dilce de Fátima Rossetti |
| Abstract | |
Analysis of Quaternary sediments in Amazonia is of great interest for reconstructing the dynamic evolution of its drainage basin, and to support discussions related to paleoclimate, sea level and tectonics. Few studies emphasize this type of approach, which is mainly due to lack of natural exposures due to the low topography of the area. This work integrates facies analysis, radiogenic dating, 13C, 15N and C/N analyses of an 124 m-thick obtained in the area located near Lake Arari, northeastern Marajó Island, State of Pará. The studied sediments were deposited in the last 50 ka, and record the following depositional environments: fluvial channel, represented by massive, moderately sorted, fine- to coarse-grained, locally conglomeratic, sand, and subordinate mud with parallel lamination, which are arranged in several fining upward cycles up to 8 m thick; outer estuarine basin to shallow marine, mainly consisting of mud with parallel to streaky lamination, interbedded with lenticular and wavy/flaser heterolithic layers, forming a coarsening upward succession; inner estuarine basin, lithologically similar to the outer estuarine basin to shallow marine deposits, with smaller thickness (up to 10 m), and with layers arranged in coarsening and fining upward cycles; tidal flat, formed by lenticular and wavy/flaser heterolithic layers, which are locally interbedded with massive sand packages up to 1 m thick, forming finning upward cycles up to 4 m thick; estuarine channel, formed by a succession about 15 m thick, consisting of fine to coarse-grained sand and, secondarily, heterolithic deposits, which are arranged in both (AU) | |