Gravimetric survey and modeling of the basement morphology in the sedimentary thickness characterization, NE portion of Paraná Sedimentary Basin - Brazil

Abstract

The northeast portion of the Paraná Sedimentary Basin is distinguished by structural highs as the known Pitanga Dome, an uplifted structure identified in the last century. It represents a geological and evolutionary evidence of the Paraná Sedimentary Basin and has undergone inspired studies and intense exploration surveys. This study consists of a gravimetric survey in the Pitanga Dome area, State of São Paulo, Brazil. The Bouguer gravity anomalies have been identified and related to the structural high, sedimentary thickness, and the basement morphology. Processing and enhancement techniques were used for forward modeling based on previous studies. The three models from profiles sectioning the dome have a sedimentary thickness varying from 200 to 1.250 meters. The adopted methodology has provided important results determining that the Pitanga Dome can be understood through rational 3D visualization. The area can be interpreted as an undulating basement with thinning of sedimentary rocks related to deep features (structures) in the crust/ mantle limit (Moho uplift). This characteristic is confirmed by the sedimentary layer thickening present throughout the surrounding area. The results also offer important insights and support for further studies concerning the genesis and evolution of this and other uplifted structures of the Paraná Sedimentary Basin. KEYWORDS:Paraná basin; Gravimetry; Modeling. RESUMO: A porção nordeste da Bacia Sedimentar do Paraná distingue-se pelos altos estruturais e o conhecido Domo de Pitanga, uma estrutura de soerguimento identificada no século passado. Representa uma evidência geológica e evolutiva da Bacia Sedimentar do Paraná sendo alvo de diversos estudos e pesquisas de exploração. Este estudo consiste em uma aquisição gravimétrica na área do Domo de Pitanga, Estado de São Paulo, Brasil. As anomalias Bouguer são relacionadas com o alto estrutural, espessura de sedimentos e morfologia do embasamento. Técnicas de processamento e realce foram usadas para modelagem direta com base em estudos anteriores. Três modelos foram gerados em perfis seccionando o domo e apresentam espessuras de sedimentos variando de 200 a 1.250 metros. A A metodologia adotada forneceu importantes resultados estabelecendo o entendimento através da visualização 3D racional do Domo de Pitanga. A área pode ser interpretada como uma ondulação do embasamento com afinamento na espessura dos sedimentos associado a estruturas em profundidade no limite crosta/manto (soerguimento da Moho). Esta característica é confirmada pelo espessamento das camadas sedimentares em toda área circundante. Os resultados também fornecem importantes subsídios e apoio a novos estudos sobre a gênese e evolução deste e de outros altos estruturais na Bacia Sedimentar do Paraná. PALAVRAS-CHAVE: Bacia do Paraná; Gravimetria; Modelagem. Gravimetric survey and modeling of the basement morphology in the sedimentary thickness characterization, NE portion of Paraná Sedimentary Basin -Brazil Aquisição gravimétrica e modelagem da morfologia do embasamento...

Intraplate Strike-Slip Corridor within South America (NE Border of the Paraná Basin) Unveiled by Structural Analysis of Faults and Fracture Swarms

“…With the aim of unravelling the geological setting of geo-resources embedded in this basin, a large number of investigations have been conducted both at the regional (basin/continental-to-subcontinental) and at the local scale. Studies include the collection of geophysical data as well as field structural measurements (e.g., Milani [37]; Milani and Zalán [26]; Strugale et al [61]; Costa et al [62]; Fries et al [63]). The gathered information revealed the main structural trends of the Precambrian basement and of the Paleozoic-to-Cenozoic covers (Zalán et al [20]; Hasui et al [64]), and confirmed the role of inherited weakness zones in the development and following deformation of the basin (Milani [37]; Zalán et al [10]; Milani and Ramos [43]; Zalán et al [20]; Almeida [11]; Campanha and Brito Neves [25]; Strugale et al [61]).…”

“…The common finding of the performed scientific investigations is that the tectonic framework of the Paraná basin, and specifically of its northeastern margin, is characterized by two main azimuthal trends of structural alignments, namely NE-SW and NW-SE (Soares et al [18]; Ferreira [69]; Fulfaro et al [17]; IPT [70]; Zalán et al [10]; Milani et al, [71]; Zalán et al [20]; Quintas [72]; Saad [73]; Strugale et al [61]; Campos et al [74]; Fries et al [63]; and Pinheiro et al [67]). These directions correspond to joints, faults, fault zones, network of faults or shear zones, morphological alignments detected from air photo, lineaments or lineament domains identified on satellite images or else from aeromagnetic and gravimetric images.…”