-PALYNOFLORAL AND PALEOENVIRONMENTAL CHARACTERIZATION OF THE SANTANA FORMATION (LOWER CRETACEOUS), 4-BO-1-PE WELL, ARARIPE BASIN, NORTHEAST BRAZIL.A paleoenvironmental characterization of the Santana Formation sedimentary rocks (4-BO-1-PE well), Araripe Basin, Late Aptian-Early Albian, was accomplished through qualitative and quantitative analyses of the palynofl ora. Palynological and lithological evidence indicate a predominantly continental depositional environment for this section, composed by a fl uvial, lacustrine deltaic system in a semi-arid climate. The detection of a single dinofl agellate cyst suggests that small sea ingressions took place during Aptian-Albian times in the region, as also verifi ed in other coeval strata of marginal Brazilian Cretaceous basins. Comparisons with palynofl oras from other continents support the hypothesis that this assemblage belongs to the North-Gondwana microfl oristic province.Key words: Araripe Basin, Lower Cretaceous, paleoenvironment, paleopalynology.RESUMO -A caracterização do paleoambiente da Formação Santana, bacia do Araripe, de idade Neoaptiana a Eoalbiana, foi realizada através de análise de associações palinofl orísticas recuperadas em testemunhos do poço 4-BO-1-PE. Evidências palinológicas e litológicas indicam um paleoambiente dominantemente continental, composto por um sistema fl uvio deltaico lacustre, sob clima quente árido a semiárido. A detecção da presença de um único exemplar de dinofl agelado corrobora a tese do início das pequenas ingressões marinhas que ocorreram durante o Aptiano-Albiano, a exemplo do verifi cado em outras bacias cretáceas brasileiras de mesma idade. A composição palinofl orística identifi cada enquadra-se àquelas observadas nas bacias do nordeste brasileiro e insere-se nas características das associações pertencentes à província microfl orística do Gondwana-Norte.Palavras-chave: bacia do Araripe, Cretáceo Inferior, paleoambiente, paleopalinologia.

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PALYNOFACIES ANALYSIS IN EVALUATION OF HYDROCARBON POTENTIAL GENERATOR OF THE POJUCA FORMATION, RECÔNCAVO BASIN. This paper deals with the study of source rock potential and its depositional environment. These strata belong to Pojuca Formation and occur in syn-rift sequence of the Early Cretaceous age (Hauterivian-Barremian) in the region of Aramari, a little-explored area of the northwestern Recôncavo Basin. The potential generator of these sediments was evaluated based on studies of palynofacies, Total Organic Carbon (TOC) analysis and Rock-Eval pyrolysis. For the evaluation of the maturation thermal of organic matter of the sediments was used the Spore Coloration Index (SCI); and the palynological study was used to identify the paleoenvironment of these strata. By integration of data from "Rock-Eval" pyrolysis and palynofacies it was possible to identify the prevalence of type II and III kerogen, with varying degrees of quality, allowing for individualization of three palynofacies. The material has predominance of amorphous organic matter of lacustrine origin, with TOC data ranging from 0.95% to 4.71%. The organic matter is a great potential hydrocarbon generator, indicated by S2 values that reach 26.33 mgHC/g rock. SCI values between 4.5-5.0 corresponding to 0.5 reflective of vitrinite (% Ro) demonstrated that the studied section is entering the maturation window. With the data acquired through palynofacies analysis and palynological associations, it can be inferred that a continental deposition environment (deltaiclake) characterizes the sedimentation of the Pojuca Formation with the presence of higrophytic and xerophytic elements, indicating that the vegetation developed in an arid and dry paleoclimate with wet niches locally and latitude next to the present. The data show that the studied area is placed in anoxic conditions containing good quality kerogen and suitable for the generation of hydrocarbons.

This paper describes a new chemical sample preparation methodology for palynological analysis with the concentration of particulate organic material. To demonstrate the method potentiality, chemical experiments were carried out on representative rock samples composed of different lithologies, environments, and ages, from five Brazilian basins. Five sedimentary samples were taken from subsurface being four from the core and one cutting, and additionally one from outcrop, making six samples. The experiments aimed to authenticate the effectiveness of using the Fluoclor chemical reagent to replacing hydrofluoric acid (HF) ordinarily used in the preparation of palynological samples. HF acid, in Brazil, has its trade restricted and controlled by the army, making its continual acquisition impossible. Because it is a chemical compound by combining hydrofluoric acid (HF) with a small addition (~ 13%) of hydrochloric acid (HCl), it is free of this control, making routine palynological samples processing method possible. To illustrate the product efficacy, tests were performed on sediments of different ages (Paleozoic, Mesozoic, and Cenozoic) and with diverse mineralogical compositions. The data obtained attended as a comparison with the same stratigraphic intervals samples, previously processed with hydrofluoric acid (HF). The results showed that, regardless of both the stratigraphic interval analyzed and the mineralogical composition of the samples, the percentage recovery of the organic groups, as well as the marine and non-marine palynomorphs, were equivalent, thus demonstrating the reliability of the new method for chemical processing palynological samples.