Cryogenian cap carbonates that overlie Sturtian glacial deposits were formed during a post‐glacial transgression. Here, we describe microfossils from the Kakontwe Formation of Zambia and the Taishir Formation of Mongolia—both Cryogenian age, post‐Sturtian cap carbonates—and investigate processes involved in their formation and preservation. We compare microfossils from these two localities to an assemblage of well‐documented microfossils previously described in the post‐Sturtian Rasthof Formation of Namibia. Microfossils from both new localities have 10 ± 1 μm‐thick walls composed of carbonaceous matter and aluminosilicate minerals. Those found in the Kakontwe Formation are spherical or ovoid and 90 ± 5 μm to 200 ± 5 μm wide. Structures found in the Taishir Formation are mostly spherical, 50 ± 5 μm to 140 ± 5 μm wide, with distinct features such as blunt or concave edges. Chemical and mineralogical analyses show that the walled structures and the clay fraction extracted from the surrounding sediments are composed of clay minerals, especially muscovite and illite, as well as quartz, iron and titanium oxides, and some dolomite and feldspar. At each locality, the mineralogy of the microfossil walls matched that of the clay fractions of the surrounding sediment. The abundance of these minerals in the walled microfossils relative to the surrounding carbonate matrix and microbial laminae, and the presence of minerals that cannot precipitate from solution (titanium oxide and feldspar), suggests that the composition represents the original mineralogy of the structures. Furthermore, the consistency in mineralogy of both microfossils and sediments across the three basins, and the uniformity of size and shape among mineral grains in the fossil walls indicate that these organisms incorporated these minerals by primary biological agglutination. The discovery of new, mineral‐rich microfossil assemblages in microbially laminated and other fine‐grained facies of Cryogenian cap carbonates from multiple localities on different palaeocontinents demonstrates that agglutinating eukaryotes were widespread in carbonate‐dominated marine environments in the aftermath of the Sturtian glaciation.

中文翻译：

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来自低温盖碳酸盐的生物凝集真核微化石。

在冰期后海侵过程中形成了覆盖斯图尔特冰川沉积物的低温盖碳酸盐岩。在这里，我们描述了来自赞比亚的Kakontwe组和蒙古的Taishir组的微化石，包括低温时代，图尔图斯帽后碳酸盐时代，并研究了它们的形成和保存过程。我们将这两个地区的微化石与先前在纳米比亚的斯图尔特后拉斯托夫组中描述的一组有据可查的微化石进行了比较。来自这两个新地方的微化石的壁厚为10±1μm，由碳质物质和铝硅酸盐矿物组成。Kakontwe组中发现的那些是球形或卵形的，宽90±5μm至200±5μm。在塔希尔组中发现的结构大多为球形，宽度为50±5μm至140±5μm，具有明显的特征，例如钝或凹陷的边缘。化学和矿物学分析表明，围墙结构和从周围沉积物中提取的粘土成分是由粘土矿物组成的，尤其是白云母和伊利石，以及石英，铁和钛的氧化物，以及一些白云石和长石。在每个地方，微化石壁的矿物学与周围沉积物的粘土部分的矿物学相匹配。相对于周围的碳酸盐基质和微生物薄片，壁微化石中这些矿物的含量很高，并且存在无法从溶液中沉淀的矿物（氧化钛和长石），表明该成分代表了该结构的原始矿物学。此外，三个盆地中微化石和沉积物的矿物学上的一致性，以及化石壁中矿物颗粒之间大小和形状的均一性表明，这些生物体是通过主要的生物凝集作用掺入了这些矿物的。在来自不同古大陆的多个地方的低温层状碳酸盐岩的微生物层合和其他细粒相中发现了新的，富含矿物质的微化石组合，这表明凝结的真核生物在斯图尔特冰川形成后广泛存在于以碳酸盐为主的海洋环境中。