Lithology and Petrology of the Stanley and Jackfork Formations

摘要: The sandstones of the Stanley and Jackfork formations represent two arenite types indigenous to geosynclines. Bedding characteristics, intra-formational stratigraphy, depositional structures are described. formation consists shale, graywacke, silts tone, siliceous tuff, interbedded in more or less rhythmic fashion. graywackes do not show clear evidence grading, although they present other features characteristic sequences graded arenites. principally sandstone, with minor amounts shale. Ripple marking bedding-plane structures, cross-bedding, rare Stanley, uncommon those Jackfork. quartz grains were assigned either an igneous a metamorphic source on basis shape. Percentages rock fragments, feldspar, heavy minerals also determined, roundness estimated. In addition, grain size distributions plotted. ...