Although intensified work on the volcaniclastic-rich sediments of the fossil-bearing Mussentuchit Member (uppermost Cedar Mountain Formation, Utah) has provided a refined chronostratigraphic framework, paleoenvironmental interpretations remain cryptic. To resolve this, we performed facies analysis and architectural reconstruction on exposed Mussentuchit Member outcrops south of Emery, central Utah, USA. Contrary to previous interpretations (fluvial, lacustrine), we identified a broad suite of facies that indicate that deposition occurred on the landward part of a paralic depocenter, influenced by both distal alluvial and proximal coastal systems. We conclude that the Mussentuchit Member was a sink for suspension-settling fines with most undergoing pedogenic alteration, analogous to the modern coastal plain of French Guiana (Wang et al. 2002; Anthony et al. 2010, 2014). However, this landward paralic depocenter was not uniform through time. Sedimentological evidence indicates landscape modification was ongoing, influenced by an altered base-level (high groundwater table, long residency of water in sediments, shifts in paleosol types, heavier to lighter δ18O, and distinct shifts in relative humidity (ε); common in coastal settings). If the above data is coupled with recent age data, we interpret that the Mussentuchit Member correlates to the S.B. 4 Greenhorn Regression (Thatcher Limestone) of the adjacent Western Interior Seaway to the east. As a landward paralic depocenter, the Mussentuchit would have been sensitive to base-level conditions in response to ongoing tectonic processes pushing the foredeep east, and lower paleo-CO2 levels coupled with a minor global sea-level fall (brief glacial phase) just before to the Cenomanian–Turonian Thermal Maximum. Altogether, our results not only strengthen linkages in the central Western Interior Seaway, but simultaneously results in novel linkages to near-coeval paralic depocenters across mid-Cenomanian North America.

中文翻译：

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美国犹他州中部雪松山组 Mussentuchit 成员沿海平原的 Paralic 沉积学

尽管对含化石的 Mussentuchit 段（犹他州雪松山组的上层）富含火山碎屑的沉积物进行了深入研究，提供了一个完善的年代地层框架，但对古环境的解释仍然很神秘。为了解决这个问题，我们对美国犹他州中部埃默里以南暴露的 Mussentuchit 成员露头进行了相分析和建筑重建。与之前的解释（河流、湖泊）相反，我们确定了一系列广泛的相，表明沉积发生在近岸沉积中心的陆地部分，受远端冲积和近端沿海系统的影响。我们得出的结论是，Mussentuchit 段是悬浮沉降罚款的汇点，其中大部分经历了成土变化，类似于法属圭亚那的现代沿海平原（Wang 等人，2002；安东尼等人。2010 年，2014 年）。然而，随着时间的推移，这个向陆的paralic depocenter并不统一。沉积学证据表明，景观正在发生变化，受基础水平变化的影响（地下水位高、水在沉积物中的长期驻留、古土壤类型的变化、δ18O 从重到轻，以及相对湿度（ε）的明显变化；在沿海地区很常见设置）。如果上述数据与最近的年龄数据相结合，我们认为 Mussentuchit 成员与东部相邻的西部内陆航道的 SB 4 Greenhorn 回归（撒切尔石灰岩）相关。作为一个向陆的近海沉积中心，Mussentuchit 对基地水平的条件很敏感，以响应持续的构造过程将前深部向东推，以及在 Cenomanian-Turonian 热最大值之前较低的古二氧化碳水平以及全球海平面的轻微下降（短暂的冰期）。总而言之，我们的研究结果不仅加强了中西部内陆航道的联系，而且同时导致了与北美中部 Cenomanian 近同时代的副沉积中心的新联系。