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| Format: | Artículo científico |
| Sprache: | en |
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Servicio Nacional de Geología y Minería
2012
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| Online-Zugang: | https://www.redalyc.org/articulo.oa?id=173924966005 |
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Inhaltsangabe:
- U-Pb zircon constraints on the age of the Cretaceous Mata Amarilla Formation, Southern Patagonia, Argentina: its relationship with the evolution of the Austral Basin Augusto N. Varela Daniel G. Poiré Thomas Martin Axel Gerdes Francisco J. Goin Javier N. Gelfo Simone Hoffmann Ciencias de la Tierra Zircons Argentina Laser ablation Foreland basin Magallanes Basin) Despite the abundant fossil content of the Mata Amarilla Formation (Southern Patagonia, Santa Cruz Province, Argentina), its age has always generated a considerable number of questions and debates. The chronological data provided by invertebrates, dinosaurs, fish, turtles, plesiosaurs and fossil flora are contradictory. In this work, twenty U-Pb spot analyses by laser ablation were carried out on the outer parts of the zoned zircon crystals from a tuff layer of the middle section of the Mata Amarilla Formation, yielding a U-Pb concordia age of 96.23±0.71 Ma, which corresponds to the middle Cenomanian. The deposition of the lower section of the Mata Amarilla Formation marks the onset of the foreland stage of the Austral Basin (also known as Magallanes Basin); this transition is characterized by the west-east shift of the depositional systems, which is consistent with the progradation of the Cretaceous fold-and-thrust belt. Thus, the onset of the foreland stage could have occurred between the upper Albian and lower Cenomanian, as the underlying Piedra Clavada Formation is lower Albian in age. On comparing the data obtained with information from the Última Esperanza Province in Chile, it can be suggested that the initiation of the closure of the Rocas Verdes Marginal Basin occurred simultaneously. 2012 artículo científico 0718-7092 https://www.redalyc.org/articulo.oa?id=173924966005 en http://www.redalyc.org/revista.oa?id=1739 Andean Geology application/pdf Servicio Nacional de Geología y Minería Andean Geology (Chile) Num.3 Vol.39