Banca de DEFESA: Rick Souza de Oliveira

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Rick Souza de Oliveira
DATE: 13/07/2023
TIME: 08:30
LOCAL: Sala de videoconferência e Teams
TITLE:

Crustal framework and tectono-sedimentary evolution of the Acre Basin

KEY WORDS:

sub-Andean Basins; Iquitos Arch; Andes; Juruá orogeny; Amazonian Craton; Sunsás.

PAGES: 288
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

Understanding of the crustal transition between orogenic zones and cratonic terranes in distal regions of foreland basins has increased, but analysis is often limited by sedimentary cover. Although the Andes are one of the classic examples of subduction, little is known about the area of influence of the fold-thrust belt in the deformation of the distal retroarc region. In this context, the Acre Basin, for presenting a lack of studies about its basement and filling, becomes a key tectonic environment due to its peculiar location, specifically between the Amazonian Craton and the sub-Andean zone, in the Peruvian flat slab region. Therefore, this thesis seeks to map the depths of the basement, estimate the crustal compositions, identify the main depocenters, structures, boundaries and propose a tectono-stratigraphic evolution for the Acre Basin in order to understand the lithospheric evolution, its relationship with the Amazonian Craton and its positioning within the Andean orogeny. For that, an integrated methodological approach was used that included potential methods, 2D seismic and well data. Tilt depth estimates indicate a basement between 500 and 7,800 m, with greater sedimentary thicknesses in the northern portion of the basin. Potential source groups were modeled between 0.1 and 22 km and Moho depths between 26 and 37 km. The modeling also points to an upper crust consisting predominantly of low-grade meta-sedimentary and metamorphic rocks and granites, indicating that the sub-Andean and Acre basins share a basement with similar composition. There are indications that the basement of the Acre Basin is essentially formed by the Sunsás province of the Amazonian Craton. Local differences in basement depth, magnetic susceptibility and exploratory potential led to the subdivision into Divisor and Xapuri sub-basins, in the north and south of the Fitzcarrald Arch, respectively. The depositional history of the Acre Basin is marked by great control exerted by faults, through an alternation between extensional and compressional regimes, where the basement and the structural inheritance of ancient faults, many times defined the deposition and the style of deformation in younger periods. The definition and mapping of six seismic units with ages between the Devonian and the Neogene, confirmed by restoration, indicated a tectonic history compatible with the main events registered in the sub-Andean basins, marked by an intercalation between syneclisis, rift and compressional regimes. Seismic units representative of the Famatinian, Gondwanide, Juruá and Andean oregenies, and the Pangea breakup were identified. The current positioning of the Iquitos Arch was conditioned by a locally non-elastic uplift mechanism related to the upper Jurassic basement high (Javari High), Cenozoic reactivation of Triassic rift faults, and by the uplift of intra-foreland basement blocks in thick-skinned tectonics during the Andean phase Quechua III. Thus, in addition to placing the Acre Basin in the context of the sub-Andean basins, composing the Foredeep of the Western Amazon installed during the Neogene, these deposits help to understand the geodynamic mechanisms and the complexity of the Andean deformation even in regions distal to the fold-thrust belt.

BANKING MEMBERS:
Interno - 113.138.381-87 - CARLOS JOSE SOUZA DE ALVARENGA - AMU
Externo à Instituição - DAVID LOPES DE CASTRO - UFRN
Externo à Instituição - FERNANDO FLECHA DE ALKMIM - UFOP
Externo à Instituição - MARTIN BERNARD RODDAZ - UPS
Presidente - 2341034 - ROBERTA MARY VIDOTTI