The Bangor Limestone is a Mississippian (Chesterian) shallow marine carbonate formation exposed over a large portion of the Interior Low Plateaus province of northern Alabama. It is dominated by oolitic grainstone and skeletal wackestone and packstone, but in one outcrop near Moulton, Alabama, the Bangor contains a five m thick, 25 m wide, oolite-biodetrital mound-tidal flat succession. This sequence is interpreted as a 4th order sea level cycle.Four petrofacies (oolite, mound, skeletal and mudstone/dolomicrite) and four diagenetic phases (iron oxide, fibrous calcite cement, calcite spar cement and dolomite) are distinguished at the study site. Iron oxide, a minor component, stained and/or coated some ooids, intraclasts and skeletal components in the oolite petrofacies. Many of the allochems were stained prior to secondary cortical growth suggesting a short period of subaerial exposure during oolite sedimentation. The oolite petrofacies also contains minor amounts of fibrous calcite cement, a first generation marine cement, and rare infiltrated micrite that might represent a second phase of marine cement, or a first phase of meteoric cement (i.e., “vadose silt”) (Dunham 1969). Intergranular pore space in all four petrofacies is filled with up to three phases of meteoric calcite spar cement. The most complete record of meteoric cementation is preserved within coralline void spaces in the mound petrofacies and indicates precipitation in the following order: (1) non-ferroan scalenohedral spar, (2) ferroan drusy spar (0.1–0.4 wt% Fe2+) and (3) non-ferroan drusy spar. The first scalenohedral phase of meteoric cement is distributed throughout the oolite and mound petrofacies. The ferroan phase of meteoric,calcite is a void-filling cement that is abundant in the mound petrofacies and less common in the skeletal and mudstone/dolomicrite petrofacies. Non-ferroan drusy calcite is pervasive throughout the Bangor Limestone at the Moulton study site.Growth of the fourth diagenetic phase, dolomite, was the dominant event in the micrite/dolomicrite petrofacies, particularly just below an irregular surface overlain by a brecciated interval. The irregular surface is interpreted as an exposure surface. Three phases of dolomite occur below the exposure surface. The majority is finely crystalline, anhedral, and enriched in Si4+, criteria which support a supratidal or mixed hypersaline έteoric origin. Secondary phases of coarser euhedral non-ferroan and ferroan dolomite are restricted to fenestrae and other voids in the micrite/dolomicrite petrofacies and were precipitated during subsequent meteoric diagenesis.Diagenesis of the Bangor Limestone at the Moulton outcrop was dominated by synsedimentary and very early meteoric processes driven by periods of subaerial exposure. Large voids within the mound petrofacies were particularly important, as they remained open long enough to record a more detailed early meteoric cement stratigraphy that might not be evident in Bangor Limestone outcrops elsewhere in Alabama.

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生物碎屑珊瑚丘复合体：密西西比班戈石灰岩早期成岩过程的关键

班戈石灰岩是密西西比（切斯特）浅海碳酸盐岩地层，暴露在阿拉巴马州北部内陆低高原省的大部分地区。它以鲕粒粒岩和骨架瓦砾岩和泥灰岩为主，但在阿拉巴马州莫尔顿附近的一处露头中，班戈包含一个 5 m 厚、25 m 宽的鲕粒-生物碎屑丘-潮坪系列。该层序被解释为第 4 级海平面旋回。研究地点区分了四种岩相（鲕粒岩、土丘、骨架和泥岩/白云岩）和四种成岩相（氧化铁、纤维状方解石胶结物、方解石晶石胶结物和白云石）。氧化铁，一种微量成分，染色和/或包覆了鲕粒岩相中的一些鲕粒、碎屑和骨骼成分。许多异质体在继发性皮质生长之前被染色，表明在鲕粒沉积过程中存在短期的地下暴露。鲕粒岩相还含有少量纤维状方解石胶结物、第一代海相胶结物和稀有的渗透泥晶，它们可能代表海相胶结物的第二相或流星胶结物的第一相（即“渗流粉砂”）（Dunham 1969 ）。所有四种岩相中的粒间孔隙空间都充满了多达三相的陨石方解石晶石胶结物。最完整的陨石胶结记录保存在丘岩相的珊瑚状空隙空间内，并按以下顺序指示降水：（1）非铁质偏三角面体晶石，（2）铁质晶石（0.1-0.4 wt% Fe2+）和（ 3) 非铁质晶石晶石。陨石胶结物的第一偏三角面体相分布在鲕粒岩和丘岩相中。陨石、方解石的铁质相是一种充填空隙的胶结物，在丘岩相中含量丰富，而在骨架和泥岩/白云石岩相中较少见。有色金属球状方解石在 Moulton 研究地点的整个班戈石灰岩中普遍存在。第四成岩阶段白云岩的生长是泥晶/白云岩岩相中的主要事件，特别是在被角砾岩层覆盖的不规则表面之下。不规则表面被解释为暴露表面。三相白云石出现在暴露面以下。大多数是精细结晶、正面体和富含 Si4+，支持潮上或混合高盐度 έteoric 起源的标准。粗自形非铁质和铁质白云石的次生相仅限于泥晶/白云石岩相中的窗孔和其他空隙，并在随后的陨石成岩作用中沉淀。 Moulton 露头的班戈石灰岩的成岩作用主要是同沉积和非常早期的陨石过程由地下暴露时间驱动。土丘岩相内的大空隙尤其重要，因为它们保持开放的时间足够长，可以记录更详细的早期陨石胶结地层，这在阿拉巴马州其他地方的班戈石灰岩露头中可能并不明显。Moulton 露头的班戈石灰岩的成岩作用主要是由地下暴露时期驱动的同沉积作用和非常早期的陨石作用形成的。土丘岩相内的大空隙尤其重要，因为它们保持开放的时间足够长，可以记录更详细的早期陨石胶结地层，这在阿拉巴马州其他地方的班戈石灰岩露头中可能并不明显。Moulton 露头的班戈石灰岩的成岩作用主要是由地下暴露时期驱动的同沉积作用和非常早期的陨石作用形成的。土丘岩相内的大空隙尤其重要，因为它们保持开放的时间足够长，可以记录更详细的早期陨石胶结地层，这在阿拉巴马州其他地方的班戈石灰岩露头中可能并不明显。