Magnetostratigraphy of the Miocene Las Arcas Formation, Santa María Valley, northwestern Argentina
The first magnetostratigraphic study of the Las Arcas Formation (Late Miocene) was carried out in Las Totoritas creek (26o12'S; 65o47'W, NW Argentina), a key place in between of two geological provinces: Northwestern Pampean Ranges and Eastern Cordillera, in northwestern Argentina. This wa...
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| Autores principales: | , |
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2015
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v63_n_p101_Spagnuolo http://hdl.handle.net/20.500.12110/paper_08959811_v63_n_p101_Spagnuolo |
| Aporte de: |
| Sumario: | The first magnetostratigraphic study of the Las Arcas Formation (Late Miocene) was carried out in Las Totoritas creek (26o12'S; 65o47'W, NW Argentina), a key place in between of two geological provinces: Northwestern Pampean Ranges and Eastern Cordillera, in northwestern Argentina. This was accompanied by isotopic dating (9.01±0.12Ma, 40Ar-39Ar in amphibole) of the unit, obtained from a 3.4m thick tuff intercalated at ~45m above the base. The Las Arcas Formation is 810m thick at the sampling locality and it is mainly composed of tabular reddish conglomerates, sandstones and siltstones in both coarsening- and thickening-upward arrangements. The exposed section was sampled at 48 sites, 26 of which are interpreted as carrying primary magnetization. The new magnetostratigraphic column was correlated with the Geomagnetic Polarity Time Scale (GPTS), and suggests that deposition of the Las Arcas Formation strata started at around 9.1Ma and ended around 6.8Ma. The paleomagnetic pole obtained for this unit (Dec=8.7° Inc=-43.9° dp=14.9dm 9.3) indicates that this area underwent non-significant rotation (11.0°±13.6°) since the Late Miocene. © 2015 Elsevier Ltd. |
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