The so-called Permian–Triassic mass extinction was followed by a prolonged period of ecological recovery that lasted until the Middle Triassic. Triassic stromatolites from the Germanic Basin seem to be an important part of the puzzle but have barely been investigated so far. Here, we analysed late Anisian (upper Middle Muschelkalk) stromatolites from across the Germanic Basin by combining petrographic approaches (optical microscopy, micro X-ray fluorescence, Raman imaging) and geochemical analyses (sedimentary hydrocarbons, stable carbon and oxygen isotopes). Palaeontological and sedimentological evidence, such as Placunopsis bivalves, intraclasts and disrupted laminated fabrics, indicate that the stromatolites formed in subtidal, shallow marine settings. This interpretation is consistent with δ¹³C_carb of about −2.1‰ to −0.4‰. Occurrences of calcite pseudomorphs after gypsum possibly suggest occasionally elevated salinities, which is well in line with the relative rarity of fossils in the host strata. Remarkably, the stromatolites are composed of microbes (perhaps cyanobacteria and sulphate-reducing bacteria) and metazoans such as non-spicular demosponges, Placunopsis bivalves and/or microconchids. Therefore, these ‘stromatolites’ should more correctly be referred to as microbe-metazoan build-ups. They are characterized by diverse lamination types, including planar, wavy, domal and conical ones. Microbial mats likely played an important role in forming the planar and wavy laminations. Domal and conical laminations commonly show clotted to peloidal features and mesh-like fabrics, attributed to fossilized non-spicular demosponges. Our observations not only point up that non-spicular demosponges are easily overlooked and might be mistakenly interpreted as stromatolites, but also demonstrate that microbe-metazoan build-ups were widespread in the Germanic Basin during Early to Middle Triassic times. In the light of our findings, it appears plausible that the involved organisms benefited from elevated salinities. Another (not necessarily contradictory) possibility is that the mutualistic relationship between microbes and non-spicular demosponges enabled these organisms to fill ecological niches cleared by the Permian–Triassic crisis. If that is to be the case, it means that such microbe-metazoan associations maintained their advantage until the Middle Triassic.

中文翻译：

---

日耳曼盆地安尼纪晚期微生物-后生动物的堆积：二叠纪-三叠纪危机的后果

所谓的二叠纪-三叠纪大灭绝之后是一段长时间的生态恢复，一直持续到中三叠纪。来自日耳曼盆地的三叠纪叠层石似乎是这个谜题的重要组成部分，但迄今为止几乎没有被研究过。在这里，我们通过结合岩相学方法（光学显微镜、微 X 射线荧光、拉曼成像）和地球化学分析（沉积碳氢化合物、稳定的碳和氧同位素）分析了来自日耳曼盆地的晚期 Anisian（上中 Muschelkalk）叠层石。古生物学和沉积学证据，例如Placunopsis双壳贝类、内碎屑和破碎的层压织物，表明叠层石形成于潮下带浅海环境中。这种解释与 δ ^13一致C_{碳水化合物}约为-2.1‰至-0.4‰。石膏后方解石假晶的出现可能表明盐度偶尔升高，这与宿主地层中化石的相对稀有性非常吻合。值得注意的是，叠层石由微生物（可能是蓝细菌和硫酸盐还原菌）和后生动物组成，如非针状海绵体、Placunopsis双壳贝类和/或微型贝类。因此，这些“叠层石”应该更准确地称为微生物-后生动物堆积物。它们的特点是不同的层压类型，包括平面、波浪、圆顶和锥形。微生物垫可能在形成平面和波浪形叠片方面发挥了重要作用。圆顶和圆锥形叠层通常显示凝结成球状特征和网状织物，这归因于化石的非针状海绵。我们的观察不仅表明非针状海绵很容易被忽视并可能被错误地解释为叠层石，而且还表明微生物-后生动物的堆积在早三叠世至中三叠世的日耳曼盆地很普遍。根据我们的研究结果，所涉及的生物从盐度升高中受益似乎是合理的。另一种（不一定是矛盾的）可能性是微生物和非针状海绵之间的共生关系使这些生物能够填补二叠纪-三叠纪危机所清除的生态位。如果是这样的话，这意味着这种微生物-后生动物的关联一直保持着它们的优势，直到中三叠世。