page_title: Rya Formation
section_title: Basin history
hierarchical_section_title: Rya Formation / Basin history
caption_attribution_description: English: Coarse summary of the locations as discussed in Blackburn, Terrence J.&#32;(2013).&#32;"Zircon U-Pb Geochronology Links the End-Triassic Extinction with the Central Atlantic Magmatic Province". Science&#32;340: 941–945. DOI:10.1126/science.1234204.
context_page_description: The Rya Formation is a geologic formation in Skåne County, southern Sweden. It is Early to early Middle Jurassic in age. The Rya Formation comprises siltstones, claystones, sandstones, mudstones and rare coal beds. The formation overlies the Höganäs Formation and is overlain by the Vilhelmsfält and Mariedal Formations.
  The formation was deposited in the Höganäs and Øresund Basins that formed in the earliest Jurassic as part of the break-up of Pangea. The 295 metres thick formation comprises four members, from base to top the Döshult, Pankarp, Katslösa and Rydebäck Members. The depositional environment of the formation ranges from continental to open marine.
  The Rya Formation has provided fossils of a number of sharks, ammonites, bivalves and ichnofossils. Coalified wood occurs as scattered pieces up to 6 centimetres long and indeterminate belemnites, echinoids, serpulids, ostracods and nodosariid foraminifera were also recorded in the formation. Iron ooids containing erratic boulders, called Geschiebe in German, attributed to the Rya Formation were found in Holstein, northern Germany.
context_section_description: Basement
  The basins where the Rya Formation was deposited form part of the Sorgenfrei-Tornquist Zone (STZ) of the Trans-European Suture Zone, the boundary between Baltica to the northeast and Peri-Gondwana to the southwest. The orogeny was active in the Late Ordovician, or approximately 445 million years ago.
  At the Carboniferous-Permian boundary around 300 Ma, the area was influenced by the Skagerrak-Centered Large Igneous Province, another large igneous province stretching across the North Sea, the eponymous Skagerrak between Denmark and Sweden and to the northwest up to northern England and Scotland.
  Break-up of Pangea
  The basins of southern Sweden and eastern Denmark were formed during the latest Triassic and earliest Jurassic. During this time the Central Atlantic magmatic province (CAMP), with an estimated 11,000,000 square kilometres (4,200,000 sq mi) the largest igneous province in Earth's history, was formed to the present southwest of the Danish-Swedish realm. In the Skåne area, the Central Skåne Volcanic Province was active during the time of deposition of the Rya Formation, commencing around the Sinemurian-Pliensbachian boundary. The earliest magmatism was partly emplaced into and across pre-existing extensional basin structures. The first and the main volcanic phase of this volcanic province occurred in the Early Jurassic (late Sinemurian to Toarcian) at 191–178 Ma. Analysis of the volcanic rocks produced by this Jurassic volcanism suggests a continental Strombolian-type eruptive character close to the oceans of the Early Jurassic. No correlative pyroclastic beds have yet been identified in sedimentary basins surrounding central Skåne.
  Toarcian
  During deposition of the Rydebäck Member, the Toarcian turnover happened. This event at the Pliensbachian-Toarcian boundary characterized by widespread anoxic conditions globally, led to the extinction of various groups of flora and fauna. Taxa inhabiting the upper water column were unaffected by anoxia and included ammonites and belemnites. Epifaunal taxa adapted to low-oxygen conditions, such as the buchiids, posidoniids and inoceramids, flourished in the post-extinction environment during the survival interval.
caption: Extent of the CAMP
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