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Piedra Lumbre Formation
The Piedra Lumbre Formation is a geologic formation that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology yields a maximum age of 1475 million years, corresponding to the Calymmian period. Description The Piedra Lumbre Formation consists of light gray to black phyllite or schist. The formation has been subject to extreme deformation within the Hondo syncline that confuses the stratigraphic picture.Bauer 2004, p.200 The formation can be divided into three members, beginning with a lower member, about thick, of quartz-muscovite-biotite-garnet-staurolite phyllitic schist. This is characterized by light gray crenulated cleavage surfaces sprinkled with small garnet, biotite, and staurolite crystals. The middle member is interbedded light gray schist and quartzite, with the top primarily black phyllitic schist with white banding. The quartzite beds towards the base of this member contain thin calcareous beds. The upper member is of phyllitic s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
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 (geology), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syncline
In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed smaller folds. Synclines are typically a downward fold (synform), termed a synformal syncline (i.e. a trough), but synclines that point upwards can be found when strata have been overturned and folded (an antiformal syncline). Characteristics On a geologic map, synclines are recognized as a sequence of rock layers, with the youngest at the fold's center or ''hinge'' and with a reverse sequence of the same rock layers on the opposite side of the hinge. If the fold pattern is circular or elongate, the structure is a basin. Folds typically form during crustal deformation as the result of compression that accompanies orogenic mountain building. Notable examples * Powder River Basin, Wyoming, US * Sideling Hill roadcut along Interstat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rinconada Formation
The Rinconada Formation is a geologic formation that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology establishes a maximum age for the Rinconada Formation of about 1723 Mya, placing it in the Statherian period of the Precambrian. Description The formation consists of gray to buff quartz-muscovite schist with some inberbedded quartzite and metaconglomerate. which fills an inverted syncline in the northern Picuris Mountains. It is missing from the Hondo Group in the Tusas Mountains. Detrital zircon geochronology establishes a minimum age for the Rinconada Formation of 1762 Mya. However, this reflects the crystallization age of the source rocks, and the true age is likely closer to 1723 Mya based on zircon ages in the underlying Ortega Formation. This indicates a shift in source region between the Ortega Formation and the Rinconada Formation. The formation is divided into three informal members. The first is composed of staurolite gne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Picuris Orogeny
The Picuris orogeny was an orogenic event in what is now the Southwestern United States from 1.43 to 1.3 billion years ago in the Calymmian Period of the Mesoproterozoic. The event is named for the Picuris Mountains in northern New Mexico and interpreted either as the suturing of the Granite-Rhyolite crustal province to the southern margin of the proto-North American continent Laurentia or as the final suturing of the Mazatzal crustal province onto Laurentia. According to the former hypothesis, this was the second in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism. Description Age and isotope data show that southern North America is composed of a series of northeast-trending provinces representing island arc terranes accreted onto the 1800 Mya core of La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hondo Group
The Hondo Group is a group of geologic formations that crops out in most of the Precambrian-cored uplifts of northern New Mexico. Detrital zircon geochronology gives a maximum age for the lower Hondo Group of 1765 to 1704 million years (Mya), corresponding to the Statherian period. Geology The Hondo Group consists of a lower very clean quartzite (the Ortega Formation) and upper schists, quartzites, and slates. The total thickness is about .Montgomery 1953 The upper section is absent in the Tusas Mountains, where the Hondo Group is essentially synonymous with the Ortega Formation. The upper section is assigned to the Rinconada Formation in the Picuris Mountains. The most complete section is in the northern Picuris Mountains, where the Hondo Group fills an overturned syncline. Detrital zircon geochronology establishes an age for the lower Hondo Group of 1765 to 1704 Mya.Jones ''et al.'' 2011 The Pilar and Piedra Lumbre Formations were originally included in the Hondo Group ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mya (unit)
Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese language, ISO 639-3 code is * Moruya Airport's IATA code * The IOC, license plate, and UNDP country code for Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ... ("MYA") People * Mya (given name) * Mya (singer) (Mya Marie Harrison, born 1979), an American R&B singer-songwriter and actress * Bo Mya (1927–2006), nom de guerre of a Myanmar rebel leader, chief rapist of the Karen National Union Other uses * ''Mýa'' (album), a 1998 album by Mýa * ''Mya'' (bivalve), a genus of soft-shell clams * MYA (unit) for "million ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. Foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression. The foliation in slate is called " slaty cleavage". It is caused by strong compression causing fine grained clay flakes to regrow in planes perpendicular to the compression. When expertly "cut" by striking parallel to the foliation, with a specialized tool in the quarry, many slates will display a property called fissility, forming smooth flat sheets of stone which have long been used for roofing, floor tiles, and other purposes. Slate is frequently grey in color, especially when seen, en masse, covering roofs. However, slate occurs in a variety of colors even from a single locality; f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of hematite. Other colors, such as yellow, green, blue and orange, are due to other minerals. The term ''quartzite'' is also sometimes used for very hard but unmetamorphosed sandstones that are composed of quartz grains thoroughly cemented with additional quartz. Such sedimentary rock has come to be described as orthoquartzite to distinguish it from metamorphic quartzite, which is sometimes called metaquartzite to emphasize its metamorphic origins. Quartzite is very resistant to chemical weathering and often forms ridges and resistant hilltops. The nearly pure silica co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staurolite
Staurolite is a reddish brown to black, mostly opaque, nesosilicate mineral with a white streak. It crystallizes in the monoclinic crystal system, has a Mohs hardness of 7 to 7.5 and the chemical formula: Fe2+2Al9O6(SiO4)4(O,OH)2. Magnesium, zinc and manganese substitute in the iron site and trivalent iron can substitute for aluminium. Properties Staurolite often occurs twinned in a characteristic cross-shape, called cruciform penetration twinning. In handsamples, macroscopically visible staurolite crystals are of prismatic shape. The mineral often forms porphyroblasts. In thin sections staurolite is commonly twinned and shows lower first order birefringence similar to quartz, with the twinning displaying optical continuity. It can be identified in metamorphic rocks by its swiss cheese appearance (with poikilitic quartz) and often mantled porphyroblastic character. Name The name is derived from the Greek, ''stauros'' for cross and ''lithos'' for stone in referenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garnet
Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different species are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. The garnets make up two solid solution series: pyrope-almandine-spessartine (pyralspite), with the composition range ; and uvarovite-grossular-andradite (ugrandite), with the composition range . Etymology The word ''garnet'' comes from the 14th-century Middle English word ''gernet'', meaning 'dark red'. It is borrowed from Old French ''grenate'' from Latin ''granatus,'' from ''granum'' ('grain, seed'). This is possibly a reference to ''mela granatum'' or even ''pomum granatum'' (' pomegranate', ''Punica granatum''), a plant whose fruits contain abundant and vivid red seed covers ( arils), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotite
Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron- endmember annite, and the magnesium-endmember phlogopite; more aluminous end-members include siderophyllite and eastonite. Biotite was regarded as a mineral ''species'' by the International Mineralogical Association until 1998, when its status was changed to a mineral ''group''. The term ''biotite'' is still used to describe unanalysed dark micas in the field. Biotite was named by J.F.L. Hausmann in 1847 in honor of the French physicist Jean-Baptiste Biot, who performed early research into the many optical properties of mica. Members of the biotite group are sheet silicates. Iron, magnesium, aluminium, silicon, oxygen, and hydrogen form sheets that are weakly bound together by potassium ions. The term "iron mica" is sometimes used for iron-rich biotite, but the term also refers to a flaky micaceou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscovite
Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavage yielding remarkably thin laminae (sheets) which are often highly elastic. Sheets of muscovite 5 meters × 3 meters (16.5 feet × 10 feet) have been found in Nellore, India. Muscovite has a Mohs hardness of 2–2.25 parallel to the 01face, 4 perpendicular to the 01and a specific gravity of 2.76–3. It can be colorless or tinted through grays, browns, greens, yellows, or (rarely) violet or red, and can be transparent or translucent. It is anisotropic and has high birefringence. Its crystal system is monoclinic. The green, chromium-rich variety is called fuchsite; mariposite is also a chromium-rich type of muscovite. Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic roc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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