| 词条 | Choiyoi Group |
| 释义 |
| name = Choiyoi Group | image = | caption = | type = Group | period = Triassic | age = Permian-Triassic | prilithology = Basaltic lava flow, breccia, andesite, rhyolitic ignimbrite | otherlithology = Dacite | namedfor = | namedby = Stipanicic et al. | year_ts = 1968 | region = | country = {{ARG}} {{CHL}} | coordinates = | unitof = Frontal Cordillera, San Rafael Massif, Principal Cordillera | subunits = El Palque Fm., Horcajos Fm., Portezuelo del Cenizo Fm., Tambillos Fm., Vega de Los Machos Fm. | underlies = Mendoza Group, Cuyo Group | overlies = | thickness = {{convert|2|–|4|km|ft|abbr=on}} | extent = | area = >{{convert|200000|km2|sqmi|abbr=on}} | map = | map_caption = }}Choiyoi Group ({{lang-es|Grupo Choiyoi}}{{refn|name=note 1|group=note|Pablo Groeber described the group as early as in 1918. Subsequently the Choiyoi Group became known by a variety of names. The current name dates to the 1968 work of Stipanicic and co-workers where the group was described in a locality in Somún Cura Massif, Río Negro Province.[1]}}) is a Permian and Triassic-aged group of volcano-sedimentary formations in Argentina and Chile. The group bears evidence of bimodal-style volcanism related to an ancient subduction zone that existed along the western margin of the supercontinent Gondwana.[1][3] The Choiyoi Group has a large areal extent through western Argentina and parts of Chile, covering at least {{convert|200000|km2|sqmi}}, but probably around {{convert|500000|km2|sqmi}}. While the subsurface extent of the group is large, exposures in Argentina are most common in the Frontal Cordillera, the San Rafael Massif and the Principal Cordillera of southern Mendoza and northern Neuquén.[1] In parts the group reaches thicknesses of 2 to 4 km.[2] The plutonic equivalent of the Choiyoi Group volcanic material are mostly granitoids.[2] The remnants of the magmatic arc that produced much of volcanic material is now preserved as a series of batholiths, including the Coastal Batholith of central Chile in the Chilean Coast Range. During the Permian the zone of arc magmatism moved 350 km inland from the Chilean Coast Range, reaching San Rafael about 280 million years ago.[3] Many Triassic basins in southern South America, including Cuyo Basin, have their lowermost sections made up of Choiyoi Group formations.[3] StratigraphyThe Choiyoi Group can be stratigraphically subdivided into a Lower Choiyoi Group and an Upper Choiyoi Group.[3] In the Lower Choiyoi Group basaltic lava flows, andesites and breccias are common.[2] Volcanic rocks and sediments in the Lower Choiyoi Group belong to the calc-alkaline magma series and have also other geochemical signatures indicative of an origin in subduction zone volcanism.[4] Volcanic rocks of the Lower Choiyoi in La Pampa and westernmost Buenos Aires Province have shoshonitic and syenitic features.[4] Part of the Lower Choiyoi Group were erupted in association with the San Rafael orogeny while some Choiyoi Group sediments were deformed by the same orogeny.[4] Rhyolitic ignimbrites and lavas are more common in the Upper Choiyoi Group.[2]The Choiyoi Group include the following formations:
Notes1. ^{{cite journal |last=Llambías |first=Eduardo J. |last2=Quenardelle |first2=Sonia |last3=Montenegro |first3=Teresita |date=2003 |title=The Choiyoi Group from central Argentina: a subalkaline transitional to alkaline association in the craton adjacent to the active margin of the Gondwana continent |url=https://www.researchgate.net/publication/235452239 |journal=Journal of South American Earth Sciences |publisher=Elsevier |volume=16 |issue= 4|pages=243–257 |doi=10.1016/S0895-9811(03)00070-1 |access-date=|bibcode=2003JSAES..16..243L }} 2. ^1 2 3 4 5 {{cite journal |last=Martinez |first=A. |last2=Giambiagi |first2=L. |date=2010 |title=Evolución petrológica y geoquímica del magmatismo bimodal Permo-Triásico del Grupo Choiyoi en el cordón del Portillo, Mendoza, Argentina |url=http://www.unioviedo.es/reunido/index.php/TDG/article/view/214 |journal=Trabajos de Geología |publisher=Universidad de Oviedo |volume=30 |issue= |pages=432–451 |doi= |language=Spanish |access-date=5 January 2016}} 3. ^{{cite journal |last=Spalletti |first=L.A. |last2=Fanning |first2=C.M. |last3=Rapela |first3=C.W. |date=2008 |title=Dating the Triassic continental rift in the southern Andes: the Potrerillos Formation, Cuyo Basin, Argentina |journal=Geologica Acta |publisher= |volume=6 |issue=3 |pages=267–283 |doi= }} 4. ^1 2 3 4 5 {{cite journal |last=Kleiman |first=Laura E. |last2=Japas |first2=María S. |date=2009 |title=The Choiyoi volcanic province at 34°S–36°S (San Rafael, Mendoza, Argentina): Implications for the Late Palaeozoic evolution of the southwestern margin of Gondwana |url=https://www.researchgate.net/publication/241406241 |journal=Tectonophysics |publisher= |volume=473 |issue= 3–4|pages=283–299 |doi= 10.1016/j.tecto.2009.02.046|access-date=5 January 2016|bibcode=2009Tectp.473..283K }} 5. ^1 {{cite journal |last=Vallecillo |first=Graciela |last2=Caballero |first2=María M. |last3=Rocher |first3=Sebastián |last4=Espin |first4=Eleonora |date=2010 |title=Analisis del grupo Choiyoi (permotriásico), cordillera frontal de Calingasta, provincia de San Juan |url=http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0004-48222010000100022&lang=pt |journal=Revista de la Asociación Geológica Argentina |publisher= |volume=66 |issue=1–2 |pages= |doi= |access-date=5 January 2016 |language=Spanish}} 6. ^1 2 {{cite journal |last=Rapalini |first=Augusto E. |last2=Vilas |first2=Juan F. |date=1991 |title=Tectonic rotations in the Late Paleozoic |url=http://gji.oxfordjournals.org/content/107/2/333.full.pdf+html |journal=Geophysical Journal International |publisher= |volume=107 |issue= 2|pages=333–351 |doi= 10.1111/j.1365-246X.1991.tb00829.x|access-date=5 January 2016}} 7. ^{{cite journal |last=Koukharsky |first=Magdalena |last2=Ottone |first2=Eduardo G. |date=2011 |title=Plantas Fósiles del Grupo Choiyoi, Cordillera Frontal a la Latitud del río Mendoza |url=http://www.scielo.org.ar/scielo.php?pid=S0004-48222011000200004&script=sci_arttext&tlng=pt |journal=Revista de la Asociación Geológica Argentina |publisher= |volume=68 |issue=2 |pages= |doi= |access-date=11 January 2016 |language=Spanish}} References{{portal|Geology|Argentina|Chile|Permian|Triassic|Prehistory of South America}}{{reflist}}{{Major South American geological formations}} 11 : Geologic formations of Argentina|Geologic formations of Chile|Permian System of South America|Permian Argentina|Permian Chile|Permian volcanism|Triassic System of South America|Triassic Argentina|Triassic Chile|Triassic volcanism|Neuquén Basin |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。