STRATIGRAPHIC, DEPOSITIONAL ENVIRONMENTAL AND PALEONTOLOGIC ANALYSIS OF THE HARRISBURG MEMBER OF THE KAIBAB FORMATION IN NORTH CENTRAL ARIZONA

Stratigraphic analysis of the Harrisburg Member of the Kaibab Formation on the north Kaibab Plateau in north central Arizona showed the presence of nine stratigraphic units. The contact between the Fossil Mountain Member and the Harrisburg Member is noted by a change from a thick-bedded cherty fossiliferous limestone, to a thin-bedded fossiliferous limestone of unit one. Unit 2 is a thin-bedded dolostone. A laminated sandstone containing well-rounded quarts grains makes up unit 3. The upper contact of unit 3 is marked by a weathered surface and represents a disconformity suggesting subaerial exposure. A poorly exposed red siltstone make up unit 4. A fossiliferous laminated dolostone with a white siliceous cap makes up unit 5. Above the fossiliferous laminated dolostone is a covered slope representing unit 6. Unit 7 is a thin-bedded fossiliferous dolostone that contains silicified nautiloids, ammonites, gastropods, trilobites and brachiopods along with burrows. Unit 8 is a covered slope. Unit 9 is the uppermost unit and contains a fossiliferous dolostone with silicified nautaloids, ammonites and gastropods. Above the Harrisburg Member is a major disconformity filled by the Rock Canyon Conglomerate and Triassic Moenkopi Formation.

Deposition of the lower part of the Harrisburg Member occurred on a shallow marine shelf during a regression representing the end of the lower Kaibab sequence. Units five through nine were deposited during a transgression, on a low energy marine shelf representing a second transgression and a younger sequence.