Early Cambrian wave-formed shoreline deposits: the Hardeberga Formation, Bornholm, Denmark

Lars B. Clemmensen, Aslaug C. Glad, Gunver K. Pedersen

    Publikation: Bidrag til tidsskriftArtikelForskningpeer review

    6 Citationer (Scopus)

    Abstrakt

    During the early Cambrian, the Danish island Bornholm was situated on the northern edge of the continent Baltica with palaeolatitudes of about 35°S. An early Cambrian (Terreneuvian) transgression inundated large areas of Baltica including Bornholm creating shallow marine and coastline environments. During this period, wave-formed shoreline sediments (the Vik Member, Hardeberga Formation) were deposited on Bornholm and are presently exposed at Strøby quarry. The sediments consist of fine- and medium-grained quartz-cemented arenites in association with a few silt-rich mudstones. The presence of well-preserved subaqueous dunes and wave ripples indicates deposition in a wave-dominated upper shoreface (littoral zone) environment, and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and/or changing meteorological conditions. Discoidal structures (medusoids) are present in the quarry, but due to the relative poor preservation of their fine-scale structures it is difficult to determine if the discoids represent true medusae imprints or inorganic structures. The preservation of the shallow-water bedforms as well as the possible medusae imprints is related to either the formation of thin mud layers, formed during a period of calm water when winds blew offshore for a longer period, or to the growth of bacterial mats. The orientation of the wave-formed bedforms indicates a local palaeoshoreline trending NE–SW and facing a large ocean to the north.

    OriginalsprogEngelsk
    Sider (fra-til)1889-1903
    Antal sider15
    TidsskriftInternational Journal of Earth Sciences
    Vol/bind106
    Udgave nummer6
    DOI
    StatusUdgivet - 1 sep. 2017

    Programområde

    • Programområde 3: Energiressourcer

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