Microbialites undergo a well – documented resurgence following the Permian – Triassic mass extinction. This comeback has been attributed to several causes, including the emptying of Early Triassic ecosystems by the severity of the extinction, a decline in burrowing activity and intensity, and the unusual chemistry of Early Triassic oceans. A laterally – continuous stromatolite horizon found within the Lower Triassic Virgin Limestone was examined at the Blue Diamond, NV U.S.A. locality in order to determine the factors that led to growth of the stromatolites, and by extension, the environmental conditions that led to the formation of widespread microbialites in the aftermath of the Permian-Triassic mass extinction. The Virgin Limestone at the study locality consists of ~6 m – thick cycles of shale and siltstone that pass upwards into bioturbated lime mudstone, and are capped by oolitic packstone or grainstone. Each ~6 m – thick cycle represents a rapid sea level rise that led to the deposition of fine – grained clastics below storm wave base, followed by deposition of coarsening – upwards carbonates that were deposited in progressively shallower environments. Analysis of redox-sensitive trace metals (U. V and Mo) from the shale and siltstone interbeds indicate that the fine – grained clastics were deposited under dysoxic waters, however, extensive bioturbation and macrofossils from the carbonate units indicates better aeration of shallower settings. The stromatolites occur within a single, laterally extensive horizon, and 4 distinct stromatolite morphologies are observed along a 3 km long transect, including: 1) aggregates of high-relief hemispherical domes and columnar stromatolites with well-developed laminae that are up to 0.75 m thick; 2) lozenge-shaped aggregates of intergrown columnar stromatolites with dimpled top surfaces; 3) isolated hemispheroids; and, 4) meandering ridges of intergrown domes that are small, low – relief (usually <7 cm), and have a clotted fabric. Isolated hemispheroids are found across the entire study area, while the large hemispherical and columnar aggregates, lozenge-shaped masses and the small intergrown domes are found in the southern, central and northern portion of the study area, respectively. Analysis of trace metals from shale directly underlying the stromatolites reveals an intensification of dysoxic conditions that may have initiated mound growth, while the occurrence of distinct burrows and a sparse fauna within the stromatolites indicates at least partially – oxygenated conditions as the stromatolites developed on the seafloor. Overall, stromatolite growth was controlled by a combination rapid calcification of the mounds related to the unusual carbonate chemistry of Early Triassic oceans, a microbial bloom driven by N – fixing diazotropic cyanobacteria, and possibly intermittent dysoxic conditions that limited grazing metazoans. Comparison of Lower Triassic stromatolites from the Blue Diamond locality to others from the western United States reveals the importance of localized conditions in initiating microbialite growth and determining the complexity of microbialite ecosystems.

二叠纪-三叠纪生物大灭绝后，微辉石经历了一次有据可查的复兴。这种卷土重来归因于多种原因，包括由于物种灭绝的严重性使早期三叠纪生态系统排空，洞穴活动和强度下降以及早期三叠纪海洋化学异常。在美国内华达州的蓝钻石地区，对下三叠纪处女石灰岩中发现的横向连续的叠层石层进行了研究，以确定导致叠层石生长的因素，进而确定了导致叠层石形成的环境条件。二叠纪-三叠纪大灭绝的结果是广泛的微生物。研究地点的初生石灰岩由〜6 m组成–页岩和粉砂岩的厚循环，向上循环进入经过生物扰动的石灰泥岩，并由橄榄质泥岩或粒岩覆盖。每个〜6 m –厚的周期表示海平面迅速上升，导致细粒碎屑沉积在风暴波基下，随后又沉积了粗化–向上沉积的碳酸盐，这些碳酸盐逐渐沉积在较浅的环境中。对页岩和粉砂岩夹层中对氧化还原敏感的痕量金属（铀和钼）的分析表明，细粒碎屑沉积在缺氧水域下，但是，碳酸盐岩单元广泛的生物扰动和大型化石表明，浅层环境通气性更好。叠层岩发生在单个横向扩展的视野内，在3 km长的样带上观察到4种不同的叠层石形态，包括：1）高浮雕半球形穹顶和柱状叠层石的聚集体，这些叠层石层厚达0.75 m，发育良好的薄片。2）互生的柱状叠层石的菱形聚集体，其顶部表面凹陷。3）孤立的半球体；4）相互交错的圆顶曲折的脊，小而低，浮雕（通常小于7厘米），且具有凝结的织物。在整个研究区域中发现了孤立的半球体，而在研究区域的南部，中部和北部则分别发现了大的半球形和柱状聚集体，菱形块和小的相互交织的圆顶。对直接在叠层石下面的页岩中的痕量金属的分析显示，可能已经引发土堆生长的缺氧条件加剧了，而叠层石内部出现明显的洞穴和稀疏动物群则表明至少有一部分是含氧条件，因为叠层石在海底发育。总体而言，叠层岩的生长受与早期三叠纪海洋异常碳酸盐化学相关的丘快速钙化，N-固定的重氮蓝细菌驱动的微生物开花以及可能限制放牧后生动物的间歇性缺氧条件的共同控制。