|
Chama Basin
The Chama Basin is a geologic structural basin located in northern New Mexico. The basin closely corresponds to the drainage basin of the Rio Chama and is located between the eastern margin of the San Juan Basin and the western margin of the Rio Grande Rift. Exposed in the basin is a thick and nearly level section of sedimentary rock of Permian to Cretaceous age, with some younger overlying volcanic rock. The basin has an area of about . Stratigraphy In stratigraphic order (youngest to oldest), the stratigraphic units of the Chama Basin are: :Cretaceous ::Graneros Shale Member, Mancos Shale ::Twowells Sandstone Tongue, Dakota Formation :: Whitewater Arroyo Shale Tongue, Mancos Shale :: Paguate Sandstone Tongue, Dakota Formation :: Clay Mesa Shale Tongue, Mancos Shale ::Cubero Sandstone Tongue, Dakota Formation ::Oak Canyon Member, Dakota Formation ::Encinal Canyon Member, Dakota Formation :Jurassic ::Burro Canyon Formation ::Morrison Formation ::Bluff Sandstone ::Summerville ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burro Canyon Formation
The Burro Canyon Formation is an Early Cretaceous Period sedimentary geologic formation, found in western Colorado, the Chama Basin and eastern San Juan Basin of northern New Mexico, and in eastern Utah, US. Description The lithology of the Burro Canyon Formation is dominated by medium- to fine-grained sandstone, much of which has rounded chert and quartz pebbles above scour surfaces. The Burro Canyon Formation was deposited in a braided-stream system. The formation overlies the Morrison Formation, with the boundary placed at the first conglomeratic sandstone bed. It underlies the Dakota Formation, from which it is distinguished by the presence of green mudstone and the absence of carbonaceous material. It is similar to the Cedar Mountain Formation on the west side of the Colorado River and the two formations have been interpreted as interfingering alluvial fans from separate source regions. The Jackpile Member of the Morrison Formation may be its lateral equival ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zuni Mountains Formation
The Shinarump Conglomerate is a geologic formation found in the Four Corners region of the United States. It was deposited in the early part of the Late Triassic period. Description The Shinarump Conglomerate is a highly resistant coarse-grained sandstone and pebble conglomerate, (minor or major conglomerates are a typical base layer after unconformities or disconformities; the Shinarump is a major conglomerate) with rare lenses of mudstone, sometimes forming a caprock because of its hardness, cementation, and erosion resistance. The Shinarump is found throughout the Colorado Plateau with significant exposures as the canyon rimrock in the vicinity of Canyon De Chelly National Monument, at the north-northeast of the Defiance Plateau/Defiance Uplift. At Canyon De Chelly the Shinarump Conglomerate was laid down upon De Chelly Sandstone-(280 Ma, an erosion unconformity of 50 my), in a region at the west foothill region of the mostly north-south trending Chuska Mountains of northeast Ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shinarump Formation
The Shinarump Conglomerate is a geologic formation found in the Four Corners region of the United States. It was deposited in the early part of the Late Triassic period. Description The Shinarump Conglomerate is a highly resistant coarse-grained sandstone and pebble conglomerate, (minor or major conglomerates are a typical base layer after unconformities or disconformities; the Shinarump is a major conglomerate) with rare lenses of mudstone, sometimes forming a caprock because of its hardness, cementation, and erosion resistance. The Shinarump is found throughout the Colorado Plateau with significant exposures as the canyon rimrock in the vicinity of Canyon De Chelly National Monument, at the north-northeast of the Defiance Plateau/Defiance Uplift. At Canyon De Chelly the Shinarump Conglomerate was laid down upon De Chelly Sandstone-(280 Ma, an erosion unconformity of 50 my), in a region at the west foothill region of the mostly north-south trending Chuska Mountains of northea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salitral Formation
The Salitral Formation is a Late Triassic geologic formation found in north-central New Mexico, primarily the northwestern Jemez Mountains. It is an older subunit of the Chinle Group (or formation), overlying the Shinarump Conglomerate and underlying the Poleo Formation. History of investigation The unit was originally designated as the Salitral Shale tongue of the Chinle Formation by Wood and Northrup in 1946, as part of their petroleum survey of the region. It was presumably named for Salitral Creek (). Lucas and Hunt raised it to formation rank in 1992 in the same study in which they raised the Chinle Formation to group rank. Other authors prefer a lower rank, as the Salitral Member of the Chinle Formation. Geology The formation consists of variegated mudstone and is assigned to the lower ( bentonitic) Chinle Group. The Salitral extensively intertongues with the underlying Shinarump Conglomerate (formerly known in the Jemez as the Agua Zarca Sandstone) and pinches out in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poleo Formation
The Poleo Formation is a geologic formation in northern New Mexico. Its stratigraphic position corresponds to the late Triassic epoch. Description The Poleo Formation is a cliff-forming formation composed mostly of yellowish-gray fine to medium sandstone, but with up to 20% conglomerate. The sandstone shows cross bedding and cuspate ripples. It resembles the Shinarump Conglomerate, and the two formations can be difficult to distinguish where they are not separated by the Salitral Formation. However, the Poleo Formation is finer grained and shows other distinguishing lithological features. The lower contact with the Salitral Formation is sharp and scoured, while the upper contact with the Petrified Forest Formation is gradational. The Poleo Formation has an inverse thickness relationship with the Salitral that suggests the thick sections fill valleys cut into the Salitral. The formation is exposed throughout the Chama Basin, the Nacimiento Mountains, and Jemez Mountains of New Mex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petrified Forest Formation
The Petrified Forest Member is a stratigraphic unit of the Chinle Formation in Arizona, Colorado, New Mexico, Nevada, and Utah. It preserves fossils dating back to the Triassic period. Subunits Beds (are in alphabetical order, asterisks (*) indicate usage by the U.S. Geological Survey, other usages by state geological surveys): * Capitol Reef Bed (UT*) * Correo Sandstone Bed (NM*) * Sonsela Sandstone Bed (AZ*,NM*) In the Chama Basin of New Mexico, the Chinle Formation is promoted to group status and the Petrified Forest Formation has the following members: * Painted Desert Member * Mesa Montoso Member The Mesa Montosa Member is up to thick and is mostly composed of sandstone (44%) and mudstone (35%), with a lesser proportion of siltstone (20%). The color is reddish brown to brown and the sandstone is thinly bedded and ripple laminated. The Painted Desert Member is up to thick and is primarily reddish brown bentonitic mudstone. The name was originally applied to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock Point Formation
The Rock Point Formation is a geologic formation in New Mexico, Arizona, and Utah. It preserves fossils dating back to the late Triassic. Description The formation is up to 70 m thick and is mostly reddish-brown and grayish-red massive siltstone and fine sandstone beds. It is the uppermost portion of the Chinle Group wherever it is exposed. In the Chama basin, its base is placed at the first persistent sandstone bed above the mudstones of the Petrified Forest Formation. Its contact with the overlying Entrada Sandstone is sharp. Fossils The Whitaker quarry of Ghost Ranch, New Mexico is believed to be located in the Rock Point Formation, although these beds have also controversially been assigned to the Owl Rock Formation. This quarry has also been referred to as the ''Coelophysis'' quarry due to preserving a large number of specimens of the early theropod dinosaur ''Coelophysis bauri''. History of investigation The unit was first named by J.W. Harshbarger, C.A. Repenning, and J. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinle Group
The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In New Mexico, it is often raised to the status of a geological group, the Chinle Group. Some authors have controversially considered the Chinle to be synonymous to the Dockum Group of eastern Colorado and New Mexico, western Texas, the Oklahoma panhandle, and southwestern Kansas. The Chinle Formation is part of the Colorado Plateau, Basin and Range, and the southern section of the Interior Plains.GEOLEX database entry for Chinle USGS (viewed 19 March 2006) A probable separate depositional basin within the Chinle is found in northwestern Colorado and northeastern U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic. The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it was well into the middle of the Triassic before life recovered its former diversity. Three categories of organisms can be distinguished in the Triassic record: survivors from the extinction event, new groups that flourished briefly, and other new groups that went on to dominate the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized subgroup of arch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entrada Sandstone
The Entrada Sandstone is a formation in the San Rafael Group found in the U.S. states of Wyoming, Colorado, northwest New Mexico, northeast Arizona, and southeast Utah. Part of the Colorado Plateau, this formation was deposited during the Jurassic Period sometime between 180 and 140 million years ago in various environments, including tidal mudflats, beaches, and sand dunes. The Middle Jurassic San Rafael Group was dominantly deposited as ergs (sand seas) in a desert environment around the shallow Sundance Sea. Description At its type section at Entrada Point, located in the northern part the San Rafael Swell in Emery County, Utah, the Entrada consists of red silty sandstone and lesser interbedded mudstone and is a slope-forming formation. This part of the Entrada is sometimes described as the "earthy facies". Here the Entrada is overlain by the Curtis Formation, and overlies the Carmel Formation.To the south and east, the Entrada transitions to cliff-forming red or white crossb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Todilto Formation
The Todilto Formation is a geologic formation in northern New Mexico and southeastern Colorado. It preserves fossils dating back to the Callovian stage of the middle Jurassic period. Description The formation consists of evaporites. It is divided into a lower calcareous shale (the Luciano Mesa Member) up to thick, and an upper gypsum bed (the Tonque Arroyo Member). Based on varve counts in the Luciano Mesa Member, the formation was laid down in a geologically brief period of time, likely in a salina (a coastal body of saline water) that was replenished both by rivers and by seepage or periodic flooding from the Sundance Sea. The varves show a 10 to 13 year periodicity that is interpreted as the solar sunspot cycle, showing that this cycle has existed for at least 160 million years. The contact with the underlying Entrada Formation is very sharp and may indicate the Todilto Sea formed catastrophically from a breach in a barrier between the basin and the Sundance Sea. The pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
