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- Title
Potencial gerador e maturidade térmica dos folhelhos da Formação Barreirinha, borda sul da Bacia do Amazonas, Brasil.
- Authors
Meirelles Góes, Vitoria Costa; Barreto Costa, Alexandre; Roberto Cerqueira, José; Caldas Abreu, Neila; Souza da Silva, Ayana; e Cima Miranda, Flávia Lima; de Souza Queiroz, Antônio Fernando; Portugal Severiano Ribeiro, Hélio Jorge
- Abstract
This work aims to evaluate the generating potential and the effect of the basic igneous intrusive on the thermal maturity of samples based on the study of organic geochemistry and palynology. A total of 15 rock samples was collected from an outcrop of Barreirinha Formation, on the Southern edge of the Amazon Basin. In this outcrop, a diabase sill was observed, which may have influenced the geochemical data of samples located at the top of the profile. The levels of total organic carbon (TOC; 0.04-2.06%) and the results of Rock-Eval pyrolysis indicate the presence of kerogen predominantly of types II and III, a potential hydrocarbon generator (S2; 0.04-3.00 mg HC / g rock) ranging from poor to medium, low concentration of free hydrocarbons (S1; 0.01-0.25 mg HC / g rock), and a variation in thermal maturity (Tmax: 359-605°C). The Terrigenous-Aquatic Ratio (TAR; 0.08-1.16) indicates the predominance of algal organic matter deposition, and the ratios of saturated biomarkers (Hopanes/Steranes; gammacerane/(gammacerane + C30 hopane); TTP / (TTP + DIA); and steranes C27- C28- C29) indicating a marine paleoenvironment with variable contribution of terrestrial components, due to the sea level oscillations that occurred during the Upper Devonian. The ratio between the isoprenoids Pristane and Phytane (Pr/Ph: 1.6-7.1) points to a sub-oxic environment. The results of gas chromatography and the saturated biomarker ratios of organic extracts [Ts/(Ts + Tm); C29 αββ/(αββ + ααα); C29S/(C29S + C29R)] indicate the variation in thermal maturity along the outcrop, and suggest the generation and migration of oil and gas, and/or the thermal degradation of some saturated biomarkers.
- Publication
Geologia USP: Série Científica, 2021, Vol 21, Issue 3, p3
- ISSN
1519-874X
- Publication type
Article
- DOI
10.11606/issn.2316-9095.v21-171844