The lower member of the Poleta Formation is well known for its abundant archaeocyaths, including an exceptionally preserved reef at Stewart’s Mill in Nevada. Large archaeocyath-bearing reefs are relatively uncommon, with most occurring as small nearshore patch reefs. Here, we describe a new 70 m-thick archaeocyath reef from the lower Poleta Formation, herein referred to as the Gold Point Reef, located near the townsite of Gold Point, Nevada. In spite of broad similarities with the Stewart’s Mill exposure, the Gold Point Reef shows an interplay between shoal and reef development over the ~ 70 m exposure that differs from what is observed at Stewart’s Mill. This reef also preserves a small shelly fauna in its uppermost 10 m, dominated by Hyolithellus. Three successive ecological stages of reef development are observed here: the pioneer stage characterized by a single rare frame-building species; the diversification stage involving about nine species of both frame-building and mud-sticking archaeocyaths; and the final foundering stage represented by one to two species of archaeocyaths and facies indicating reef demise, including abundant grainstone/packstone shoals and a silicified upper bed with a settlement of hyolitheminthes. During the apex of reef development here, there are large modular archaeocyaths, which were able to produce thick secondary skeletal tissue for a firm attachment; these archaeocyaths were capable of building large reefs in a variety of settings. Additionally, the carbon isotope profile recorded in the Gold Point Reef shows similarities to nearby exposures of the equivalent lower Poleta Formation, with the exception of a small negative downturn at the top of the reef that is not found in other locations. Combined with the documentation of facies changes over short lateral distances, the isotope data suggest that archaeocyathan reefs may have been time-transgressive across the shelf during deposition of the lower Poleta. Additionally, our work suggests that both here and globally, the specific biotic assemblage reflected the local influences of the environment on reef development, creating highly variable coeval paleocommunities even within a restricted area.

Poleta组的下层成员以其丰富的古生代而闻名，包括在内华达州Stewart's磨坊中保存完好的珊瑚礁。大型的带有古生物礁的礁石相对少见，大多数发生在小的近岸斑块礁上。在这里，我们描述了一个位于内华达州金点镇附近的，来自下波列塔组的新的70米厚的古礁，这里称为金点礁。尽管与斯图尔特磨坊的曝晒有着广泛的相似性，但金点礁显示了在约70 m的暴露时间内浅滩和珊瑚礁发育之间的相互作用，这与斯图尔特磨坊的观察结果有所不同。该礁还在其最高的10 m处保留了一个小的带壳动物区系，该区域以Hyolithellus为主。这里观察到珊瑚礁发育的三个连续生态阶段：以单个稀有框架构建物种为特征的先驱阶段；多样化阶段涉及大约九种框架构筑和粘泥古藻种；最终的建立阶段以一到两种古生物和岩相为代表，表明珊瑚礁灭绝，包括大量的花岗岩/ pack石浅滩和硅酸盐化的上层床，并沉积有玻璃状菊苣。在这里礁石的顶端发育过程中，有大型的模块化古珊瑚礁，它们能够产生较厚的次生骨骼组织，从而牢固附着。这些古细菌能够在各种环境中建造大型礁石。此外，金点礁中记录的碳同位素剖面显示出与附近的等低波列塔形成区附近的曝露相似，不同之处是在礁顶顶部有一个小的负倾角，而在其他位置则没有。结合沿短侧向相的相变记录，同位素数据表明，下波莱塔沉积期间，古礁珊瑚礁可能在整个大陆架上随时间变化。此外，我们的工作表明，无论是在本地还是全球，特定的生物群落都反映了环境对珊瑚礁发育的局部影响，即使在有限的区域内，也创造了高度变异的中世纪古群落。结合沿短距离的相变的记录，同位素数据表明，在下波莱塔沉积期间，古礁珊瑚礁可能在整个大陆架上随时间变化。此外，我们的工作表明，无论是在本地还是全球，特定的生物群落都反映了环境对珊瑚礁发育的局部影响，即使在有限的区域内，也创造了高度变异的中世纪古群落。结合沿短侧向相的相变记录，同位素数据表明，下波莱塔沉积期间，古礁珊瑚礁可能在整个大陆架上随时间变化。此外，我们的工作表明，无论是在本地还是全球，特定的生物群落都反映了环境对珊瑚礁发育的局部影响，即使在有限的区域内，也创造了高度变异的中世纪古群落。