Chinle Formation
!!Under Construction and Review!!
Paleogeographic map of Utah during the time
that the Chinle Formation was deposited.
(Blakey, 2008)
The Chinle epicontinental deposits are found between Moab and Springdale, spanning south- eastern Utah to most of northern and northwest Arizona. Formed mostly in the Carnian and some Norian stages in the Late Triassic series of the Triassic period (230- 208 MY) in the Mesozoic Era, Chinle sedimentation is thought to have occurred in an enclosed continental basin. It represents a complex of alternating lacustrine and fluvial depositional systems.
The Petrified Forest National Park in Arizona contains fossilized conifer logs, which became driftwood on the Chinle River floodplains. The largest collection of petrified driftwood in a concentrated amount is found here, but the rest of the Chinle formation also contains some fossilized wood.
Driftwood located here has exquisite detail formed from the wood's cell tissue going through silification. Because of the silification process, silica is needed to fossilize the wood. It is thought one source of silica could have been a bentonitic volcanic ash. Chinle sediment was transported from the south, but Arizona doesn’t have any volcanoes of the appropriate age to contribute to the silification. It is predicted, if a bentonitic volcano’s ash provided the silica, it would have come from Nevada or even California, as there are bentonitic volcanoes of fitting age.
Conifers are the most commonly found fossilized plants in the Chinle Formation. Cycads, ferns, spores, pollen and horsetails also appear in the rock but not as abundantly. Eoginkos, fresh- water clams, snails, ostracods, fish, other small amphibians and reptiles are rare, but are found preserved within the Chinle formation. The Phytosaur, resembling a crocodile with a more slender snout, is also found, along with a theropod Coephysis.
Uranium mineralization is found to have occurred in Chinle stream deposits.
The Petrified Forest National Park in Arizona contains fossilized conifer logs, which became driftwood on the Chinle River floodplains. The largest collection of petrified driftwood in a concentrated amount is found here, but the rest of the Chinle formation also contains some fossilized wood.
Driftwood located here has exquisite detail formed from the wood's cell tissue going through silification. Because of the silification process, silica is needed to fossilize the wood. It is thought one source of silica could have been a bentonitic volcanic ash. Chinle sediment was transported from the south, but Arizona doesn’t have any volcanoes of the appropriate age to contribute to the silification. It is predicted, if a bentonitic volcano’s ash provided the silica, it would have come from Nevada or even California, as there are bentonitic volcanoes of fitting age.
Conifers are the most commonly found fossilized plants in the Chinle Formation. Cycads, ferns, spores, pollen and horsetails also appear in the rock but not as abundantly. Eoginkos, fresh- water clams, snails, ostracods, fish, other small amphibians and reptiles are rare, but are found preserved within the Chinle formation. The Phytosaur, resembling a crocodile with a more slender snout, is also found, along with a theropod Coephysis.
Uranium mineralization is found to have occurred in Chinle stream deposits.
