Isotope geochronology and vertebrate paleontology in Mexico: Panorama and critical appraisal
The combined isotopic/paleontologic approach drove a qualitativeleap in understanding Earth’s geologic history/evolution, yet, in spiteof its early start, it is still not widely used in México. Here we report 28sites where such an approach was applied; their space/time distributionis uneven, leaving...
| Autores: | , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2015 |
| País: | México |
| Institución: | Universidad Nacional Autónoma de México |
| Repositorio: | Redalyc-UNAM |
| OAI Identifier: | oai:redalyc.org:57240685011 |
| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=57240685011 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciencias de la Tierra Mexico Cenozoic Jurassic Cretaceous geochronology |
| Sumario: | The combined isotopic/paleontologic approach drove a qualitativeleap in understanding Earth’s geologic history/evolution, yet, in spiteof its early start, it is still not widely used in México. Here we report 28sites where such an approach was applied; their space/time distributionis uneven, leaving morphotectonic provinces and/or geochronologicintervals little or not studied at all. The sites are located in eightmorphotectonic provinces, their age spans the Jurassic-Pliocene asfollows: Baja California Península (BCP), one Cretaceous and oneMiocene site. Northwestern Ranges, Basins and Plains (NW), oneMiocene site. Sierra Madre Occidental (SMOc), four Miocene sites.Central Plateau (CeP), one Late Eocene and eight Miocene/Pliocenesites. Sierra Madre Oriental (SMOr), one Jurassic and one Miocenesites. Trans-Mexican Volcanic Belt (TMVB), two Miocene and threePliocene sites. Sierra Madre del Sur (SMS), one Eocene and threeMiocene sites. Sierra Madre de Chiapas (SMCh), one Miocene site.The Chihuahua-Coahuila sierras, basins and plateaus, Gulf CoastalPlain and Yucatan Platform lack such sites.The Pliensbachian Huizachal site (SMOr) lies in the rift system thatsplit central-eastern Pangea and contains Mexico’s oldest vertebratefauna. The Late Campanian El Rosario site (BCP) is located in thenamesake Forearc Basin, its fauna shows moderate endemism. TheCenozoic sites lie in graben structures and record episodes of tectonicand magmatic activity. The Eocene Marfil (CeP) and Yolomécatl (SMS)sites occur in post-Laramide basins, their Bridgerian and Duchesnian/Chadronian faunas show boreal affinities and strong endemism. TheEarly Miocene Tubutama (NW) and Suchilquitongo (SMS) sites recordtectonic/magmatic activity around 20 Ma, and their faunas displayNorth American affinities and moderate endemism.The Middle Miocene La Purísima (BCP), Matatlán (SMS), ElCamarón (SMS) and Ixtapa (SMCh) sites record tectonic and magmaticactivity circa 15 Ma; the three latter ones disclose a volcanic beltextending from central Oaxaca to northern Chiapas; their faunasshow North American affinities and evidence local cladogenesis.The Late Miocene Paso del Águila (SMOr), El Resbalón, Cofradía,Tepezalá, El Trapiche (SMOc), Rancho El Ocote (CeP) and Tecolotlán(TMVB) sites record tectonic/magmatic activity between 9.5 and 5.0Ma; their mammals involve Late Clarendonian-Early Hemphillianand Hemphillian chronofaunas. The younger fauna reveals an earlyappearance of South American taxa in North America. The importantChapala site (TMVB) still lacks isotopic ages associated to Late Tertiaryvertebrates.The pliocene GTO 43, Rancho El Ocote, GTO 2D, Garbani,GTO 11, Pantera, GTO 12B, Estancia, GTO 5A, Rancho El Ocote,GTO 55 sites (CeP), Santa María Amajac, Charo and Buenaventura sites(TMVB) record a 4.5–3.5 Ma tectonic/volcanic activity; their Blancanchronofauna includes numerous South American taxa, disclosing thatthe Great American Biotic Interchange reached its peak. These sites/sequences als |
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