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首页> 外文期刊>Brazilian Journal of Geology >Facies analysis, sequence stratigraphy and chemostratigraphy of the Sete Lagoas Formation (Bambui Group), northern Minas Gerais State, Brazil: evidence of a cap carbonate deposited on the Janu??ria basement high
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Facies analysis, sequence stratigraphy and chemostratigraphy of the Sete Lagoas Formation (Bambui Group), northern Minas Gerais State, Brazil: evidence of a cap carbonate deposited on the Janu??ria basement high

机译：巴西米纳斯吉拉斯州北部Sete Lagoas组（Bambui组）的相分析，层序地层学和化学地层学：沉积在Janu ?? ria基底高处的碳酸盐盖层证据

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Sedimentary rocks of the Sete Lagoas Formation, exposed in the left margin of the S?￡o Francisco river (Minas Gerais State, Brazil), were deposited on the Janu??ria-Itacarambi basement high. They show both lateral and vertical rock stacking along continuous outcrops, allowing us to carry out detailed facies analysis and sequence stratigraphy studies. Our studies also integrate data from geological mapping, macro and microscopic petrography and high-resolution C and O isotope analysis. Eight facies and four facies associations make up a sequence composed by a transgressive tract in the base, and a high stand tract in the upper portion, separated by a maximum flooding surface. The high stand tract shows a progradation stacking from the basement high apex towards progressively deeper basement areas. This stratigraphic framework, associated with others stratigraphic and isotopic features, indicates that the now exposed Janu??ria basement high also represents a paleo-high during the sedimentation event. Aragonite pseudomorphs and dolomites coupled with ?′ 13 C values of -5a?° characterize the basal carbonate of the transgressive tract as a cap carbonate. Records of the Cloudina fossil, recognized in the high stand tract, indicate a Late Ediacaran age for the upper portion of the studied stratigraphic sequence.
机译：Sete Lagoas组的沉积岩暴露在圣弗朗西斯科河（巴西米纳斯吉拉斯州）的左边缘，沉积在Januria-Itacarambi地下室的高处。它们显示了沿连续露头的横向和纵向岩石堆积，使我们能够进行详细的相分析和层序地层学研究。我们的研究还整合了地质制图，宏观和微观岩相学以及高分辨率C和O同位素分析的数据。八个相和四个相的组合构成了一个序列，该序列由基部的海侵道和上部的高立位道组成，并由最大的淹没面隔开。高站道显示出从地下室高顶点到逐渐变深的地下室区域的堆积。该地层框架与其他地层和同位素特征有关，表明现在暴露的Janu ?? ria基底高也代表了沉积事件期间的古高。文石假晶型和白云岩加上-5'α°的α'13 C值将海侵道的基碳酸盐表征为帽状碳酸盐。在高阶地带中认识到的Cloudina化石的记录表明，所研究地层序列的上部具有晚埃迪卡拉纪。

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