Print this pageAbstract: Petrology and Petrography of Great Blue Formation at Wellsville Mountain, Utah
Great Blue Formation (Upper Mississippian) in the Deweyville section of Wellsville Mountain, Utah, is composed of seven distinct facies. Three members are formed by these seven facies: (1) lower limestone member; (2) median shale member; and (3) upper limestone member. Facies forming each member are as follows, from the top down: upper limestone member, (7) mudstone-packstone dolomite sandstone facies, (6) wackestone facies; median shale member, (5) mudstone-packstone claystone facies; and lower limestone member, (4) mudstone-packstone facies, (3) oolite facies, (2) wackestone-packstone facies, (1) wackestone dolomite sandstone facies.
These facies accumulated in an unstable depocenter in the eastern part of the Cordilleran miogeosyncline and are interpreted as having formed in the following environments: shoaling ooid-producing marine waters; very small localized reefs or banks of mostly solitary corals, accompanied by bryozoans and crinoids forming behind the shoal; skeletal detritus scattered behind the small localized reefs or banks; a pelletal-enriched zone behind skeletal detritus; and lagoonal conditions behind the pelletal zone and nearest to the craton. Shifts or oscillations of the environment of deposition within these facies may have been abrupt, producing sharp contacts between individual units with occasional complete changes in rock type.
AAPG Search and Discovery Article #90961©1978 AAPG Annual Convention and Exhibition, Oklahoma City, Oklahoma