|Premise||Unit, defined by Van Adrichem Boogaert and Kouwe (1995).|
|Derivatio nominis||Named after the small river Geul in the south of the province of Limburg and adjoining Belgium, where some outcrops of this subgroup can be found.|
|Type section||Location map||See figure (pdf)|
|Depth||2438 to 4303 m|
|Length||1865 m along hole|
|Definition||Group of formations, comprising a cyclic succession of predominantly fine-grained siliciclastic deposits devoid of coal seams. In the northwestern offshore the subgroup locally includes a sandstone-dominated succession.|
|Age||The deposits of the Geul Subgroup are roughly Namurian in age, but locally they can extend into the Westphalian A. For palynological marker species, the reader is referred to Smith (1967) and Clayton (1977) . Figure C.2 (see pdf) presents the ranges of a number of palynomorph marker species in the Netherlands. Biostratigraphic resolution can attain a high degree of detail in the Namurian by combining palynological data with information on goniatites (in marine bands), conodonts, ostracodes, foraminifers or macroscopic plant remains (including megaspores). A review of these zonations is given by Paproth (1983) .|
|Depositional Setting||The deposits of this subgroup reflect the first stage of the Silesian basin: delta sedimentation in a lacustrine basin with frequent marine incursions. The subgroup demonstrates a long-term regression from north to south. Depositional cycles start with a basal marine band, followed by a thick coarsening-upward interval, composed of fine-grained turbiditic and deltaic sands and mudstones. Some cycles are capped by a massive mouth bar or distributary-channel sandstone. Delta-plain deposits (coal seams) are absent from the Geul Subgroup|
|References||See References Upper Carboniferous|
Van Adrichem Boogaert, H.A. & Kouwe, W.F.P., 1993-1997. [Stratigraphic unit]. In: Stratigraphic Nomenclature of the Netherlands.
Retrieved [Datum] from [url].