The Kupferschiefer (German for Copper Shale, also called Copper Slate) or Kupfermergel (Copper Marl), (T1 or Z1) is an extensive and remarkable sedimentary unit in Central Europe. The relatively monotonous succession is typically 30 to 60 centimetres (12 to 24 in) and maximum 2 metres (6.6 ft) thick, but extends over an area of 600,000 square kilometres (230,000 sq mi) across the Southern Permian Basin. The Kupferschiefer can be found in outcrop or in the subsurface straddling six countries, including parts of the southern North Sea. The lateral equivalent outcropping in England is called Marl Slate.
Despite its distinctive nature, the Kupferschiefer is not ranked as a formation but is officially declared a sub-unit of the Werra Formation, the lowest formation of the Zechstein Group, overlying the Rotliegend Group. The unit has been dated to 257.3 ± 1.6 Ma, placing it in the Wuchiapingian stage of the Late Permian.
The Kupferschiefer comprises black shales, bituminous marls, mudstones and limestones deposited mostly in an open marine setting, with the borders of its extension deposited in a shallow marine environment. At time of deposition, the area what is now northern Europe was covered by an enclosed sea; the Zechstein sea, characterized by anoxic conditions.
The Kupferschiefer is renowned for hosting one of the most important copper deposits in the world, which were mined at least since 1199 AD. Other mineral resources found in the unit include zinc, vanadium, lead and silver.
The Kupferschiefer is also an important lagerstätte; having provided fossils of early Archosauromorph reptiles, the ancestors to modern crocodiles and extinct dinosaurs, as well as pareiasaurs, many fossil fish, including Coelacanthus granulatus, Dorypterus hoffmanni and Palaeoniscum freieslebeni, flora and other fossils. Famous finds from the unit include Parasaurus geinitzi, Protorosaurus speneri, Weigeltisaurus jaekeli and Glaurung schneideri.
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