page_title: Rya Formation
section_title: Depositional environments
hierarchical_section_title: Rya Formation / Description / Depositional environments
caption_attribution_description: English: Laurasia (Laurentia , Baltica, and Siberia) forming the northern part of the supercontinent Pangaea at 200 Ma. Made using GPlates: Citations: Golonka, J. (2007), Late Triassic and Early Jurassic palaeogeography of the world, Palaeogeography, Palaeoclimatology, Palaeoecology, 244(1-4), 297-307. Müller, R., M. Sdrolias, C. Gaina, and W. Roest (2008), Age, spreading rates, and spreading asymmetry of the world's ocean crust, Geochemistry, Geophysics, Geosystems, 9(Q04006), 19. Seton, M., R. Müller, S. Zahirovic, C. Gaina, T. Torsvik, G. Shephard, A. Talsma, M. Gurnis, M. Turner, and M. Chandler (2012), Global continental and ocean basin reconstructions since 200 Ma, Earth-Science Reviews, 113(3-4), 212-270. Torsvik, T., and R. Van de Voo (2002), Refining Gondwana and Pangea Palaeogeography: Estimates of Phanerozoic non dipole (octupole) fields, Geophysical Journal International, 151(3), 771-794. Wright, N., S. Zahirovic, R. D. Müller, and M. Seton (2013), Towards community-driven, open-access paleogeographic reconstructions: integrating open-access paleogeographic and paleobiology data with plate tectonics, Biogeosciences, 10, 1529-1541
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: Deposition of the Rya Formation began with nearshore coarse clastics, and continued with offshore mudstones with tempestites (the Döshult Member), followed by offshore muddy sediments with a brief non-marine interval (the Pankarp Member), and ended with deposition of open marine low-energy deposits (Katslösa and Rydebäck Members). The marine Rya Formation shows an overall fining-upwards trend, and an up-section bathymetric deepening of the depositional environment. The depositional environment in western Skåne was either physically protected from the storm energy due to basin topography, or deposition in Skåne took place below storm wavebase. Berthierine ooids occur scattered in the Katslösa
  Member and are increasingly abundant up-section in the Rydebäck Member. There is a possibility that iron ooid formation was promoted by precipitation of iron and silica from volcanic fluids rising up through the substrate, as has been reported from modern marine sediments offshore Indonesia. This hypothesis has emerged with the publication of age data for the volcanic rocks in Skåne, which now appear to be comparable in age to the prominent iron ooid-bearing deposits, i.e. the Rydebäck Member and the Röddinge Formation.
caption: Early Jurassic paleogeography
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