Record details

Title
    Modern and Palaeozoic iron ooids - a similar volcanic origin
Statement of responsibility
    U. Sturesson, J.M. Heikoop, M.J. Risk
Author
    Heikoop, J. M.
    Risk, M. J.
    Sturesson, U.
Language
    anglicky
Source title - serial
    Sedimentary geology
Vol./nr.
    Vol. 136, no. 1-2
Pages
    p. 137-146
Year
    2000
Notes
    3 obr., 2 fot., 2 tab.
    il.
    Obsahuje bibliografické odkazy
    Zkr. název ser.: Sedimentary Geol.
Subject group
    Barrandien
    chamosit
    geologie mořská
    hematit
    limonit
    ooid
    ordovik
    petrogeneze
    pražská pánev
    recent
    rudy Fe
    sedimentace lagunární
    sedimentace mořská
    sedimentace recentní
    struktura oolitická
    vulkanismus
Geographical name
    ČR-Čechy
    Ejpovice (Rokycany)
    Estonsko
    Indonésie
    Švédsko
    Velká Británie-Wales
Keyword
    Iron
    Modern
    Ooids
    Origin
    Palaeozoic
    Similar
    Volcanic
Abstract (in english)
   The discovery of an unconsolidated deposit of iron ooids of a kind not previously described, and in the vicinity of a volcanic island in Indonesia has shed new light on the genesis of many ancient iron oolites. The discovery shows that iron ooid formation is geologically a rapid process. The ooids form by chemical precipitation of cryptocrystalline iron oxyhydroxides on available grains on the seafloor, from seawater enriched with Fe, Al and Si. The enrichment can be a result of hydrothermal fluids, volcanic ash falls into shallow basins or rapid weathering of fresh volcanic rocks Ordovician iron ooids from northern Europe are strikingly similar to the modern ooids in chemical composition, REE distribution and internal structures. The differences in mineralogy can be explained as diagenetic transformation reactions under different environments.
   A model for the formation of the Ordovician iron ooids in northern Europe from volcanoclastic material is presented, which could be applicable to other ancient oolites in the world
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    9. 2. 2007
Import date
    8. 8. 2012