The Precuyano cycle in northern Cordillera del Viento corresponds to a volcano-sedimentary sequence with U-Pb zircon SHRIMP ages between 187. 9 ± 1.8 and 181.2 ± 2.4 Ma (Pliensbachian to lower Toarcian). The lower section is predominantly basic to mesosilicic with few clastic and a distinctive jasper level. The upper section is volcanic, essentially of acidic nature. This sequence which is continental with records of restricted marine environment and represents the transition from sin-rift to post-rift stages, was assigned to the Colomichicó Formation and correlates with La Primavera and Milla Michicó Formations that crop out to the south of this mountain range. Magmatic zircons indicate a source with strong juvenile component of Neoproterozoic age and a subordinate component of recycled Mesoproterozoic crust. The inherited zircons suggest incorporation into the magma of crustal rocks with ages between Paleozoic and Archaean with mixed juvenile component and crustal recycling. Multi-elemental diagrams, together with La/Nb > 1, Ba/ Nb > 40, La/Ta > 25, Ba/La > 20 and Ta/Hf < 0.15 ratios prevailing for the basic to mesosilicic rocks characterize a magmatism generated in a volcanic arc, showing intraplate affinity (La/Ta < 25, Ta/Hf > 0.15 and Ba/La decrease) towards the top of the sequence. The interruption of the subduction that must have occurred at this latitude from Late Permian to late Early Jurassic according with diverse authors lead to explain this magmatism through melting by decompression of a mantle affected by metasomatism related to a previous subduction process.
|Number of pages||26|
|Journal||Revista de la Asociacion Geologica Argentina|
|Publication status||Published - 2018|
- volcanismo bimodal
- Pliensbachiano - Toarciano
- Cordillera del Viento
- bimodal volcanism