|
Tererro Formation
The Tererro Formation is a Formation (geology), geologic formation in Sangre de Cristo Mountains of New Mexico. It preserves fossils dating back to the early Mississippian. Description The formation is mostly crystalline or calcarenite limestone with a total thickness of up to . It is exposed throughout the Sangre de Cristo Mountains and in the San Luis basin, San Luis, Las Vegas-Raton basin, Las Vegas-Raton, Palo Duro basin, Palo Duro, and Estancia Basins, as well in the western Tusas Mountains and the Nacimiento Mountains. It lies Unconformity (geology), unconformably on the Espiritu Santo Formation and is unconformably overlain by the Log Springs Formation in the Nacimiento Mountains, the Flechado Formation in the northern Sangre de Cristo Mountains, and the La Pasada Formation in the southern Sangre de Cristo Mountains. The formation is divided into the Macho Member (geology), Member, which is a massive ledge-forming limestone breccia (thickness ); the Turquillo Member, a th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Luis Basin
The San Luis Valley is a region in south-central Colorado with a small portion overlapping into New Mexico. The valley is approximately long and wide, extending from the Continental Divide on the northwest rim into New Mexico on the south. It contains 6 counties and portions of 3 others. It is an extensive high-elevation depositional basin of approximately with an average elevation of above sea level. The valley is a section of the Rio Grande Rift and is drained to the south by the Rio Grande, which rises in the San Juan Mountains to the west of the valley and flows south into New Mexico. The San Luis Valley has a cold desert climate but has substantial water resources from the Rio Grande and groundwater. The San Luis Valley was ceded to the United States by Mexico following the Mexican–American War. Hispanic settlers began moving north and settling in the valley after the United States made a treaty with the Utes and established a fort in the early 1850s. Prior to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conglomerate (geology)
Conglomerate () is a clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel-size clasts. A conglomerate typically contains a matrix of finer-grained sediments, such as sand, silt, or clay, which fills the interstices between the clasts. The clasts and matrix are typically cemented by calcium carbonate, iron oxide, silica, or hardened clay. Conglomerates form by the consolidation and lithification of gravel. They can be found in sedimentary rock sequences of all ages but probably make up less than 1 percent by weight of all sedimentary rocks. In terms of origin and depositional mechanisms, they are closely related to sandstones and exhibit many of the same types of sedimentary structures, e.g., tabular and trough cross-bedding and graded bedding.Boggs, S. (2006) ''Principles of Sedimentology and Stratigraphy.'', 2nd ed. Prentice Hall, New York. 662 pp. Friedman, G.M. (2003) ''Classification of sediments and sedimentary rocks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, W. H. Freeman, 2nd ed, 529 pp. The term ''mudstone'' is also used to describe carbonate rocks ( limestone or dolomite) that are composed predominantly of carbonate mud. However, in most contexts, the term refers to siliciclastic mudstone, composed mostly of silicate minerals. The NASA Curiosity rover has found deposits of mudstone on Mars that contain organic substances such as propane, benzene and toluene. Definition There is not a single definition of mudstone that has gained general acceptance,Boggs 2006, p.143 though there is wide agreement that mudstones are fine-grained sedimentary rocks, composed mostly of silicate grains with a grain size less than . Individual grains this size are too small to be distin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breccia
Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, tectonic breccia, igneous breccia, impact breccia, and hydrothermal breccia. A megabreccia is a breccia composed of very large rock fragments, sometimes kilometers across, which can be formed by landslides, impact events, or caldera collapse. Types Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. Like conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. These indicate that the gravel was deposited very close to its source area, since other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Member (geology)
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features ( facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Pasada Formation
The La Pasada Formation is a geologic formation in the southern Sangre de Cristo Mountains of New Mexico. It preserves fossils dating back to the early to middle Pennsylvanian. Description The formation is a cyclic carbonate consisting of alternating limestone and shale with some thin sandstones. Total thickness is . The formation is more clastic towards its base (50% shale and siltstone) than towards its upper portion (24% shale and siltstone). The shales are noncalcareous and greenish towards the base but become gray, calcareous, and often fossiliferous towards the upper portion. The formation shows considerable lateral variability, grading into the Flechado Formation to the north. The lower half of the formation is interpreted as a shallow marine nearshore sequence with occasional nonmarine intervals with thin coal beds. The upper half was deposited under neritic offshore marine conditions with infrequent nonmarine intervals. File:Pasada massive bed.jpg, Massive li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flechado Formation
The Flechado Formation is a geologic formation in the northern Sangre de Cristo Mountains of New Mexico. It preserves fossils dating back to the early to middle Pennsylvanian. Description The Flechado Formation consists of low- feldspar sandstone and shale alternating with thin beds of limestone. The total thickness is . It overlies the Tererro Formation and is overlain by the Alamitos Formation. The formation is well to extremely well cemented in the type area, so that it can be difficult to distinguish from the Precambrian Ortega Formation. The formation grades laterally into the La Pasada Formation to the south of the Rio Pueblo, with the clastic beds of the Flechado abruptly thinning and transitioning to carbonate beds of the La Pasada over a distance of about . The terrigenous sediments of the Flechado Formation were likely derived from the southern part of Uncompahgre uplift during uplift on the west side of the Picuris-Pecos fault. File:Flechado Formation type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Log Springs Formation
The Log Springs Formation is a geologic formation in the Jemez, Nacimiento, and Sandia Mountains of New Mexico. Its age is poorly constrained but is thought to be Namurian (late Mississippian to early Pennsylvanian). Description The Log Springs Formation is a sequence of continental red beds interpreted as reworked terra rossa soils and sediments from nearby highlands filling karst topography in the underlying Arroyo Penasco Group. Its outcrops are spotty everywhere but near the type section in the southern Jemez Mountains, where it is thick, and it does not crop out in the Sangre de Cristo Mountains. The lowermost 3 meters of the formation are hematitic shales with numerous 1 to 5 mm oolites or pisolites. The upper part of the formation is an upward coarsening sequence of crossbedded argillaceous reddish sandstones. These include abundant clasts of Precambrian gneiss, greenstone, and quartz. Though lacking in fossils, the formation is estimated as being Namurian (late Mis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity (geology)
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nacimiento Mountains
The Sierra Nacimiento (official name), or Nacimiento Mountains, are a mountain range in the northwestern part of the U.S. state of New Mexico. They are just west of the more prominent Jemez Mountains near the town of Cuba, and are separated from them by the Río Guadalupe and the Río de Las Vacas. This article will consider them as a unit together with the San Pedro Mountains, which are a smaller range contiguous with the Sierra Nacimiento on the north, and which are also part of the Nacimiento UpliftConfusingly, Nacimiento Peak is more properly part of the San Pedro Mountains. SeNacimiento Peak on TopoQuest and lie at the edge of the greater San Juan Basin, which sits atop the Colorado Plateau.Fagan 2005, p. 46. The combined range runs almost due north-south with a length of about 40 mi (65 km). The highest point in the combined range is the high point of the San Pedro Peaks, known unofficially as San Pedro Peak, 10,605 ft (3,232 m).The San Pedro Peaks are a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tusas Mountains
The Tusas Mountains are a mountain range in northern New Mexico, extending slightly into southern Colorado. They are considered the southeasternmost part of the San Juan Mountains. Grouse Mesa, , is the highest peak in the range. The mountains are located to the west of Taos and northwest of Santa Fe. The Tusas Mountains are a wide region of upland mesas and gently sloping mountains, dissected in places by deep canyons. Geography The eastern part of the range is primarily located in the Carson National Forest, bordered by the Taos Plateau volcanic field and Rio Grande del Norte National Monument to the east. It provides the headwaters for the Rio San Antonio, a tributary of the Conejos River (which flows into the Rio Grande in Colorado), and further south the Rio Tusas and Rio Vallecito, which form the Rio Ojo Caliente, a tributary of the Rio Chama (also a Rio Grande tributary). Numerous volcanic features are located along the eastern edge of the range bordering the Taos plateau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
