Data from: Xianella: a new mat-forming calcified cyanobacterium from the Middle–Late Ordovician of North China

Xianella hongii gen. et sp. nov. is described from the Middle–Late Ordovician of Shaanxi, China and interpreted as a calcified cyanobacterial sheath. Xianella filaments formed cable-like strands that constructed thick fenestral layers. The specimens occur in metre-sized limestone blocks, possibly derived from local collapse of a reefal platform margin. In combination with micrite, some of which is intraclastic and peloidal, Xianella created thick and extensive stacks of layered calcified fenestral fabric that appear to be synsedimentarily calcified open-frame mat deposits. The fenestrae range from small, laminose and very irregular, to large equidimensional areas ~2 cm across. Fenestrae with rounded outlines resemble primary gas bubbles observed in present-day microbial mats. These delicate fabrics are comparable in structure and quality of preservation with those of some Proterozoic silicified stromatolitic mats.

本文记述了产自中国陕西中晚奥陶世的新属新种洪氏Xianella（Xianella hongii gen. et sp. nov.），该类群被认定为钙化蓝细菌鞘。其丝状体形成缆绳状丝束，并构筑出厚实的窗孔层。标本赋存于米级石灰岩块体中，其来源大概率为礁型台地边缘的局部垮塌事件。该属与微晶灰岩（部分为内碎屑及球粒微晶灰岩）共同形成了厚层且广泛分布的层状钙化窗格构造，这类构造应属于同沉积钙化的开放式框架席状沉积体。其窗孔形态多样，从小型层状且极不规则的结构，跨度至直径约2厘米的大型等轴状区域。轮廓圆润的窗孔与现代微生物席中观测到的原生气泡构造极为相似。这些精细的构造在结构特征与保存质量上，可与部分元古宙硅化叠层石席相媲美。