U-Pb and Lu-Hf zircon geochronology of the Cañadón Asfalto Basin, Chubut, Argentina: Implications for the magmatic evolution in central Patagonia

摘要: Abstract The Canadon Asfalto basin, central Chubut, Argentina, comprises a volcano-sedimentary sequence related to the opening of Atlantic Ocean during Mesozoic times. Lonco Trapial, and Calcareo formations are main units evolution this basin. Las Chacritas Puesto Almada members distinguished in Formation. LA-HR-ICP-MS U-Pb Lu-Hf data on zircon were obtained these units. Trapial Formation gave weighted average age 172.3 ± 1.8 Ma. A pyroclastic level from Member 168.2 ± 2.2 Two concordant ages 160.3 ± 1.7 Ma laminated tuffite 158.3 ± 1.3 for Member. maximum depositional constrain sedimentary provenance areas basin: 1) sample Sierra de la Manea range, where controversial unit either or formation occurs, an 176.6 ± 1.0 younger crystals indicate that may be 2) sandstone with cross-stratification 173.6 ± 6.4 In terms isotopes, two magmatic events identified Patagonia: Mamil Choique event characterized by negative e Hf values around −5.0 representing recycling Permian times Mesoproterozoic crust (T DM ∼1.5 Ga), (−8.2) positive (+4) Meso- Neoproterozoic T between 1.5 0.8 Ga. is three cycles: C1 magmatism, C2 volcanism, C3 volcanism. These cycles Marifil, Chon Aike El Quemado volcanics Patagonia Neuquen Basin Mesozoic.