How old is the chinle formation

What can the rocks tell us? Think of the colorful layers as pages in a massive book. The first chapter of this geological text is the Chinle Formation. Chinle Formation. The colorful badland hills, flat-topped mesas, and sculptured buttes of the Painted Desert are primarily made up of the Chinle Formation, mainly fluvial river related deposits. Pleistocene and Holocene Epoch 1. At higher elevations in the northern part of the park, ,year-old dunes can be found. Younger dunes, around 10, years old, are found in drainage areas that contain sand such as Lithodendron Wash.

The youngest dunes are found throughout the park, in all settings, deposited around a thousand years ago. These dune deposits are largely stabilized by vegetation, especially grasses. While not as numerous as the fossils of the Chinle Formation, fossils have been found even in the quaternary sediments, including fragments of an ancestral proboscidean elephants and their relatives, such as mammoths. During the Late Miocene and Early Pliocene Epochs of the Neogene Period million years ago a large lake basin with ephemeral lakes covered much of Northeastern Arizona.

Fine-grained fluvial and lacustrine lake related sediment such as silt, clay, and sand represent the lower part of the Bidahochi Formation. Volcanoes, both nearby and as far as the Southwestern Nevada Volcanic field, spewed ash and lava over the land and into the basin.

Many of the volcanoes were phreatomagmatic, when ground or lake-water mingled with eruptive material magma to cause explosive eruptions. The resulting ash formed fine-grained deposits that were deposited within the lake sediments. After a few million years of erosion, most of the Bidahochi Formation has been removed from the park area, leaving volcanic scoria cones and maars flat-bottom, roughly circular volcanic craters of explosive origin.

The vent from one of these maars is exposed on the Painted Desert Rim across the park road to the east of Pintado Point. Chinle Formation [of Dockum Group]. Claystone, micaceous, greenish, red with reduction spots, interbedded with sandstone, fine-grained, in thin beds.

Thickness up to feet. Age is Triassic. Rowley, P. Is oldest bedrock unit mapped in the quadrangle, but is shown on cross section to unconformably overlie Moenkopi Formation Lower Triassic in the subsurface; unconformably underlies Glen Canyon Sandstone Upper Triassic and Lower Jurassic.

Map unit described as soft to moderately resistant medium-red and pink, or subordinate light-gray and light-green, thin- to medium-bedded ripple-marked cross-bedded siltstone, fine-grained sandstone, claystone, and shale.

Only a partial section, about 40 m ft thick, is exposed. It belongs to the upper member and the upper siltstone member of Poole and Stewart High and others and Picard , however, included the upper and red siltstone members of Poole and Stewart in the Nugget Sandstone. Map unit about m ft thick in nearby areas Poole and Stewart, , and generally thickens southward in the Colorado Plateaus province Stewart and others, Map unit described as shale, siltstone, sandstone, thin limestone lentils, and mudstone; mostly dusky-red with thin greenish shales; thickness up to 1, ft.

Chinle thought to be equivalent to the entire Dockum sequence and therefore not a suitable term for a part of Dockum. Dubiel, R. Was deposited in a complex fluvial-deltaic-lacustrine system. Paleovalleys eroded into underlying Moenkopi Formation by degradational fluvial system in Chinle time.

Contains numerous fossils--fish scales and bones, lungfish burrows, SCOYENIA worm burrow , coprolites, conchostracans, ostracods, vertebrates, gastropods, and pelecypods. Subsequent rise in baselevel in Chinle time resulted in infilling of the paleovalleys. First, paleovalleys filled in Shinarump time; second, headward deposition proceeded up paleovalleys, the water table rose, seasonal flooding, and increased volcanic activity occurred in Monitor Butte and Moss Back times; third, sinuous, ash-laden channels, splays, and floodplains prograded over marshy areas in Petrified Forest time; fourth, lakes, ponds, and streams existed in Owl Rock time; and fifth, as a result of a lower water table, playa mudflat and ephemeral channel sandstones deposited in Church Rock time.

Lucas, S. Correlation chart. Rock Point Member, formerly assigned as the basal member of the Wingate in area, is reassigned to the Chinle. Rock Point has geographic distribution, depositional environment, lithology, bedding, and sedimentary characteristics similar to Chinle, but dissimilar from cliff-forming sandstone of the eolian erg of the restricted Wingate.

No one has disputed the correlation of these two members with each other, and with the Dolores Formation. Lukachukai Member of Wingate abandoned. Sandstone formerly assigned to the Lukachukai are assigned to the Wingate Sandstone.

Not used in east-central NM. Upper Triassic rocks of east-central NM were deposited in a basin separated from the one in which Chinle of the Colorado Plateau was deposited. Name Dockum Group or Formation not used because Dockum was not defined precisely. Upper Triassic rocks formerly assigned to Chinle in east-central NM are renamed. The lower shale member of Chinle is named Garita Creek Formation. The upper shale member is named Bull Canyon Formation. Redonda Member of Chinle is redesignated Redonda Formation.

Overlies Moenkopi Formation disconformably. Underlies Iyanbito Member of Entrada Sandstone disconformably. Bluewater Creek replaces use of Monitor Butte in this area. Petrified Forest divided into a lower part, Sonsela Sandstone Bed, and an upper part. History of nomenclature chart. Divided in Valencia, Socorro, and Lincoln Cos. Santa Rosa Formation is used to the east in Lincoln Co. The red-brown conglomerate, sandstone, siltstone, and mudstone of the Upper Triassic Chinle Formation in the Eagle basin is a succession of fluvial channel, floodplain, lacustrine-deltaic, lacustrine, and eolian deposits.

The conglomerate was deposited in paleovalleys cut into the underlying State Bridge Formation. Sediment transport directions were from the ancestral Uncompahgre and the ancestral Front Range. Upper part thins due to erosion prior to deposition of the overlying Entrada Sandstone. A tropical monsoonal climate suggested for early Chinle time. Eolian deposits in the upper part are due to drier climatic conditions caused by the northward migration of Pangea moving CO out of the monsoonal climes.

Correlation chart and cross sections showing detailed relationships of parts of Chinle. These sandstones are older than the eolian sandstone above the Chinle in the Eagle basin.

The upper unit is lighter in color than the lower unit, and is probably a correlative of the Lower Jurassic Navajo Sandstone to the south in UT. Cross section and correlation chart show divisions of Chinle in northern UT and adjoining northern CO.

Hintze, L. Conformably overlies Moenkopi Formation; conformably underlies Moenave Formation. Combined thickness of members is up to m. Former usage and, if known, replacement name given in parentheses. This may be explained within brackets [ ]. USA Gov U. Department of the Interior U. Geologic Unit: Chinle Search archives.

Publication: Gregory, H. Summary: Pg. Summary: Chinle formation. Publication: Wilmarth, M. Publication: Dobrovolny, Ernest, and Summerson, C. Summary: Divided into a lower member to ft thick and the newly named Redonda member.

Publication: Wood, G. Publication: Bachman, G. Publication: Robeck, R. Publication: Harshbarger, J. Publication: Stewart, J.

Hence, the biotic turnover preserved in the mid-Sonsela Member at PFNP is also middle Norian in age, but may, at least partially, be an artifact of a condensed section. Model 2 following the magnetostratigraphic-based age model for the CPCP core 1A suggests instead that the ages from the lower and middle Sonsela Member are inherited populations of zircon crystals that are 1—3 Ma older than the true depositional age of the strata.

This results in a model in which no sudden decrease in sediment accumulation rate is necessary and implies that the base of the Sonsela Member is no older than ca.

Our age models demonstrate the powers, but also the challenges, of integrating detrital CA-ID-TIMS ages with magnetostratigraphic data to properly interpret complex sedimentary sequences. Shibboleth Sign In. OpenAthens Sign In. Institutional Sign In. Sign In or Create an Account. User Tools. Sign In. Advanced Search. Skip Nav Destination Article Navigation. Close mobile search navigation Article navigation.

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