The early Permian was a key interval for the evolution of terrestrial ecosystems and tetrapods. One such ecosystem is preserved in the Bromacker lagerstätte (~294 Ma) of the Tambach Formation in the Thuringian Forest, central Germany. The depositional environments, climate, and tectonic evolution of the Tambach Formation have remained debated due to limited exposure and the absence of complete borehole data. We integrate new sedimentological observations from outcrops and two research boreholes drilled in 2022–2023 adjacent to the fossil site. Redbed lithofacies represent fluvial and alluvial architectural elements throughout the section, subdivided into four members. The Bielstein-Konglomerat overlies a slight angular unconformity above older sedimentary units in the west and fills paleovalleys within a rhyolitic complex in the east, comprising conglomeratic braidplain deposits interfingering northward with floodplain facies. The overlying Tambach-Sandstein consists of channelised sandstones of a braided channel belt in the south that grade into an episodically flooded floodplain towards the north. This fining-upward succession is terminated by the Bromacker-Sandstein, which contains metamorphic and granitic gravel derived from uplifted elements of the Mid-German Crystalline High. Shale-lined reactivation surfaces in channel sandstones indicate ephemerality within the fluvial system of the Bromacker-Sandstein which hosts the Bromacker lagerstätte in associated floodplain deposits. The Finsterbergen-Konglomerat records subsequent progradation of ephemeral distributary systems from the northwest. The Bielstein-Konglomerat and Tambach-Sandstein formed under stable tectonic and climatic conditions with perennial streams, whereas the Bromacker-Sandstein and Finsterbergen-Konglomerat record increasing aridity, seasonality, and periodic desiccation, imposing adaptive stress on the ecosystem. • Facies analysis of the Tambach Formation, hosting the Early Permian Bromacker Lagerstätte. • 3D facies distribution within the Tambach Basin derived from outcrops and new drillcores. • Aridification trend and tectonic relief building recognized within the late Asselian Tambach Formation.
Stubenrauch et al. (Sun,) studied this question.