Abstract An integrated palynological and geochemical approach has been initiated to date and to precise the geochemical events of the Pimenteiras Formation, in the Late Devonian from the Parnaiba Basin, Brazil. Based on good biostratigraphic markers and presence of index species among miospores, acritarchs and chitinozoa, the investigated sequences are referred to the Middle to early Late Frasnian. Among Miospores, Chelinospora concinna and Verrucosisporites bulliferus are likely to be from the BPi Interval Zone defined in the Amazon Basin. Chitinozoans of the Early to early Late Frasnian Angochitina (Lagenochitina) avelinoi zone of the Parnaiba Basin are present, and acritarch assemblages are also consistent with a Middle to early Late Frasnian age, by comparison to assemblages previously described in other Brazilian basins. Some important accompanying species of palynomorphs are illustrated. In the studied outcrops, black shale intervals are referred to top of the Radioactive Sale B and Radioactive Shale C according to Rodrigues (1995) definitions. Top of Radioactive Shale B shows good concentration of terrestrial organic matter, but low potential source of gas. By comparison Radioactive Shale C of the upper part of the Pimenteiras Formation, with important concentration of marine organic matter have low to high potential as source of gas and condensate. This study shows that a progressive flooding took place during the Devonian period in the Parnaiba Basin with maximum marine transgression in the Frasnian. These global events of interest for hydrocarbon exploration, are regarded as markers for Gondwanan regional chronostratigraphic correlations.

中文翻译：

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巴西 Parnaíba 盆地 Frasnian 全球海侵的孢粉学和地球化学

摘要 迄今为止，已经启动了一种综合孢粉学和地球化学方法，以精确计算巴西 Parnaiba 盆地晚泥盆世 Pimenteiras 组的地球化学事件。基于良好的生物地层标记和在小孢子、亚克氏菌和几丁质动物中存在的指示种，所研究的序列被称为中晚期弗拉斯期早期。在 Miospores 中， Chelinospora concinna 和 Verrucosisporites bulliferus 可能来自亚马逊盆地定义的 BPi 间隔区。存在 Parnaiba 盆地早至晚 Frasnian Angochitina (Lagenochitina) avelinoi 带的几丁质动物群，与先前在其他巴西盆地中描述的组合相比，acritarch 组合也与中至早晚 Frasnian 时代一致。说明了一些重要的孢粉型伴生物种。在所研究的露头中，根据 Rodrigues (1995) 的定义，黑色页岩层段被称为放射性页岩 B 和放射性页岩 C 的顶部。放射性页岩 B 顶部显示了良好的陆地有机质浓度，但潜在的气源较低。相比之下，Pimenteiras 组上部的放射性页岩 C 具有重要的海洋有机质浓度，作为气源和凝析油的潜力从低到高。这项研究表明，在泥盆纪期间，Parnaiba 盆地发生了渐进式洪水，弗拉斯尼阶的海侵最大。这些对油气勘探感兴趣的全球事件被视为冈瓦纳地区年代地层相关性的标志。