SILICIFIED ONCOIDS IN THE MUSCHELKALK (MIDDLE TRIASSIC) OF KLEINHERINGEN (THURINGIA): Documentation of a Unique In Situ Microfacies Horizon

This paper documents a rare occurrence of silicified oncoids within the Lower/Middle Muschelkalk (Middle Triassic) at Kleinheringen, Thuringia. The study, based on "rescue geology" during bridge construction, reveals how early diagenetic silicification acted as a selective preservative, protecting microbial laminations from later compaction and recrystallization. The find identifies a paleo-shoal environment and provides a critical in situ reference for analogous oncolitic cherts found as erratics in Upper Silesia (Poland). As the site is now permanently inaccessible due to infrastructure development, this documentation serves as a unique record of the Germanic Basin’s microfacies variability and diagenetic history.