A poorly understood Mississippian to basal Pennsylvanian succession is preserved in parts of northern Utah, western USA. The mudrock- and carbonate-dominated Manning Canyon Formation and lateral equivalents have been referred to as “cyclothems” and might therefore be expected to preserve a record of repeated, late Paleozoic sea-level excursions similar to cyclothemic successions elsewhere in the paleotropics. In this paper, we document the sedimentology and stratigraphy of the Serpukhovian to earliest Bashkirian Manning Canyon Formation, focusing on surface exposures in the Oquirrh and Uinta Mountains and a cored subsurface intersection from central Utah. Four facies associations were identified in the Manning Canyon Formation: Mid-Shelf, Muddy Inner Shelf, Deltaic, and Coastal Plain, which are herein interpreted in the context of a muddy, semi-enclosed, epicontinental carbonate shelf fringed by a low-relief coastal plain. These facies associations are broadly comparable to recent and extant environments from a range of equatorial, clay-rich, deltaic, coastal plain, and offshore carbonate-producing environments in the Caribbean Sea, northern Australia, and SE Asia, which can be used as first-order analogues for the Manning Canyon Formation. These modern analogues suggest that several relative sea-level excursions of <40 m are recorded in the unit. The stratigraphically oldest records of substantial relative sea-level oscillations are in the lowermost Manning Canyon Formation. These preceded a more sustained pattern recorded by at least nine 4th-order, high-frequency and high-magnitude (≥40 m) sea-level cycles that characterize the upper two-thirds of the formation. Sea-level highstands are recorded by open marine shelf facies, whereas lowstands are recorded by incised channel and valley fills, and (presumed) laterally equivalent paleosols and thin coals. No record of high frequency/high magnitude relative sea-level oscillations comparable in character to those preserved in the Manning Canyon Formation was documented in the underlying stratigraphy. It is concluded that the Manning Canyon Formation may record the main onset of the eustatic signal associated with the main phase of the late Paleozoic Ice Age at ~330 Ma.

在美国西部犹他州北部的部分地区，人们对密西西比州到宾夕法尼亚州的基础演替一无所知。以泥岩和碳酸盐为主的曼宁峡谷地层及其横向等价物被称为“旋回”，因此有望保留与​​古生物学中其他地方的旋回演替相似的古生代晚期重复海底偏移的记录。在本文中，我们记录了Serpukhovian到最早的Bashkirian Manning峡谷地层的沉积学和地层学，重点研究了Oquirrh和Uinta山脉的地表暴露以及犹他州中部的带芯地下交汇处。在曼宁峡谷地层中确定了四个相系：中层架，泥泞的内层架，三角洲和沿海平原，在此以泥泞为背景进行解释，半封闭的陆上碳酸盐岩架，边缘为低浮起的沿海平原。这些相的关联可广泛地与加勒比海，澳大利亚北部和东南亚的一系列赤道，富含粘土，三角洲，沿海平原和近海碳酸盐岩生产环境中的最新和现存环境相比较。曼宁峡谷地层的有序类似物。这些现代的类似物表明，该单元中记录了<40 m的几个相对海平面偏移。相对海平面剧烈波动的地层最古老记录位于最低的曼宁峡谷地层。在形成更持久的模式之前，至少有九个四阶，高频和高震级（≥40m）海平面周期记录下来，这些周期是地层上部三分之二的特征。海平面高位是通过开放的海陆架相记录的，而低位则是通过切入的河道和河谷填充物以及（假定的）横向等效的古土壤和薄煤来记录的。在下层地层中，没有记录到与曼宁峡谷组中所保留的高频率/高幅相对海平面振荡有关的记录。结论是，曼宁峡谷组可能记录了与晚古生代冰期的主要相相关的约330 Ma的喜讯信号的主要发作。在下层地层中，没有记录到与曼宁峡谷组中所保留的高频率/高幅相对海平面振荡有关的记录。结论是，曼宁峡谷组可能记录了与晚古生代冰期的主要相相关的约330 Ma的喜讯信号的主要发作。在下层地层中，没有记录到与曼宁峡谷组中所保留的高频率/高幅相对海平面振荡有关的记录。结论是，曼宁峡谷组可能记录了与晚古生代冰期的主要相相关的约330 Ma的喜讯信号的主要发作。