Tapeats Sandstone

Within the eastern Grand Canyon, the Tapeats Sandstone is separated from the underlying Precambrian rocks by the Cambrian Sixtymile Formation.In one basin, the Cambrian Sixtymile Formation is preserved in a synclinal paleotopographic low in the Great Unconformity and separates the Tapeats Sandstone from it and the Grand Canyon Supergroup.The highest paleomonadnocks on this paleosurface are composed of Shinumo Quartzite and other erosion resistant strata of the Grand Canyon Group form paleocuestas of lesser and intermediate height.[2][11] In the western Grand Canyon, the Tapeats Sandstone unconformably overlies a similar hilly and weathered paleosurface underlain by the Vishnu Basement Rocks.The relief on the Great Unconformity in the Grand Canyon represents ancient valleys and hills that influenced sedimentation patterns within the Tapeats Sandstone along with the local basement lithology.[3][11][13] Throughout the Grand Canyon area, the Precambrian bedrock underlying the Tapeats Sandstone and Great Unconformity was extensively weathered and eroded during prolonged periods of subaerial exposure.Last studied by Sharp in 1940,[13] a highly altered ancient weathering horizon is locally preserved within the Precambrian rocks immediately underlying the Tapeats Sandstone.[11][15] The Tapeats Sandstone consists of a mixture shallow marine, intertidal, and coastal plain deposits associated with an eastward advancing shoreline.[9][10][11] In 2018, Karlstrom and others studied the age of detrital zircons from the Tapeats Sandstone in the Grand Canyon and southern Nevada using U-Pb dating.The extensive Tonto Trail lies on parts of the Tapeats Sandstone, and the platform on the south side of Granite Gorge.
Figure 1. A geologic cross section of the Grand Canyon. [ 12 ]
Stratigraphic rangePreꞒRedwall LimestoneGeological formationTonto GroupBright Angel ShaleVishnu Basement RocksUnkar GroupNankoweap FormationChuar GroupSixtymile FormationsandstoneconglomerateUnited States of AmericaTapeats Creekgeologic formationgeologic unitPhanerozoicstrataArizonaCaliforniaNevadaMuav LimestoneFrenchman Mountain Dolostonetype localitysedimentary structurescross-beddingconglomeraticquartzfeldsparcross sectionGreat Unconformityangular unconformityGrand Canyon SupergroupnonconformitymetamorphicplutonicpaleosurfacepaleomonadnocksShinumo Quartzitepaleocuestasregolithinvertebrateburrowstrace fossilsbrachiopodstrilobitesarthropodsOlenelluslingulateLingulapaterinateobolellidbioturbatedannelidgastropodscrustaceanszirconsU-Pb datingTonto TrailVishnu SchistGeology of the Grand Canyon areaSauk sequencePalaeoworld