| 词条 | Valle Alto Formation |
| 释义 |
| name = Valle Alto Formation | period = Tithonian | age = Late Jurassic ~{{fossil range|150|145}} | image = | imagesize = | caption = | type = Geological formation | prilithology = Shale, sandstone | otherlithology = Conglomerate | unitof = Quebradagrande Complex | subunits = | underlies = | overlies = | thickness = | area = | map = Blakey 150Ma - COL.jpg | map_caption = Paleogeography of Northern South America 150 Ma, {{small|by Ron Blakey}} | location | coordinates = {{coord|5|22|08|N|75|22|03|W|display=inline,title}} | region = Caldas Department Central Ranges Andes | country = {{COL}} | extent = | namedfor = Hacienda Valle Alto | namedby = González et al. | year_ts = 1977 | location_ts = San Félix | coordinates_ts = {{coord|5|22|08|N|75|22|03|W|display=inline}} | paleocoordinates_ts = {{coord|3.1|N|72.4|W|display=inline}} | region_ts = Caldas | country_ts = {{COL}} | thickness_ts = }} The Valle Alto Formation ({{lang-es|Formación Valle Alto}}, Jva) is a geological formation of the Central Ranges of the Colombian Andes. The formation is composed of shales, sandstones and conglomerates and dates to the Late Jurassic period. Ammonites and fossil flora have been found in the Valle Alto Formation. EtymologyThe formation was described and named in 1977 by González et al. after Hacienda Valle Alto, San Félix, Caldas.[1][2] LithologiesThe Valle Alto Formation is composed of shales, sandstones and conglomerates.[3] Stratigraphy, age and depositional environmentThe Valle Alto Formation, part of the Quebradagrande Complex, is not defined as a proper formation, rather as a collection of rocks of different facies origin segmented by tectonic forces of the Central Ranges.[1] The Valle Alto Formation has been deposited as the result of marine incursions from the proto-Caribbean into Colombia, preceding the larger-scale transgression of the Cretaceous.[4] Fossil contentFossils of Piazopteris branneri,{{refn|group=note|Piazopteris branneri listed as the Permian genus Glossopteris (branneri)[6]}} Cladophlebis sp., Classopollis sp., Ctenozamites sp., Desmiophyllum sp., Gleichenites sp., Nilssoniopteris sp., Otozamites sp., Pachypteris sp., Ptilophyllum sp., Rhabdoderas sp., Sagenopteris sp., Sandlingites sp., Sphenopteris sp., Substeuroceras sp., Trigonia sp., and Zamites sp. have been found in the Valle Alto Formation.[5][6] Outcrops{{Location map+ | Colombia Caldas Department| relief = 1 | width = 330 | float = left | places = | lat_deg = 5.368959 | lon_deg = -75.367470 | mark = Blue pog.svg | marksize = 12 | caption = Type locality of the Valle Alto Formation in Caldas }} The Valle Alto Formation is found near its type locality in the Central Ranges of the Colombian Andes, around Pácora and Salamina.[1] {{clearleft}}See also{{portal|Colombia|Paleontology|Prehistory of South America|Jurassic}}{{icon|FAC}} Geology of the Eastern Hills {{icon|B}} Geology of the Ocetá Páramo {{icon|C}} Geology of the Altiplano Cundiboyacense{{clearboth}} Notes1. ^1 2 Moreno Sánchez et al., 2007 2. ^Mojica, 1984, p.132 3. ^Isagen, 2009, p.9 4. ^Mojica & Kammer, 1995, p.170 5. ^1 Mojica, 1984, pp.131-132 6. ^Valle Alto Formation at Fossilworks.org References{{reflist|20em}}Bibliography
Maps
10 : Geologic formations of Colombia|Jurassic System of South America|Jurassic Colombia|Tithonian Stage|Fossiliferous stratigraphic units of South America|Paleontology in Colombia|Sandstone formations|Shale formations|Shallow marine deposits|Geography of Caldas Department |
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