Origen y edad del complejo ultramáfico-máfico Tampanchi (Ecuador)
- F. Villares-Jibaja 1
- I.F. Blanco-Quintero 2
- A. García-Casco 1
- Pedro Reyes 3
- C. Lázaro 1
- J.A. Proenza 4
- 1 Univ. de Granada
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2
Universitat d'Alacant
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- 3 Escuela Politécnica Nacional, Ecuador
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4
Universitat de Barcelona
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ISSN: 1576-5172
Ano de publicación: 2021
Título do exemplar: X Congreso Geológico de España
Número: 18
Páxinas: 464
Tipo: Artigo
Outras publicacións en: Geotemas (Madrid)
Resumo
The Tampanchi Ultramafic-Mafic Complex, located in the Cordillera Real (Ecuador), is an oval-shaped intrusive body (6 km x 3 km) intruded within a metavolcanic and metavolcano-sedimentary sequence of Jurassic-Cretaceous age (Litherland et al., 1994). The main lithologies are wehrlite, olivine hornblende clinopyroxenite, hornblendite, hornblende gabbro, hor- nblende-bearing anorthosite, and leucogranite. These lithologies do not distribute in a concentric pattern and their contact relations are gradational and intrusive. Olivine and pyroxene show cumulate texture, while textural relations of amphibole in hornblendite and pyroxenite suggest reaction-replacement of pyroxene. Mineral composition, whole-rock geochemistry, and Rb-Sr and Sm-Nd isotopic data point to arc-related magmatism with similar characteristics to Alaskan-type complex. Estima- tions based on mineral composition suggest a hydrated basaltic parental magma emplaced at intermediate to shallow crustal levels (~3.5 kbar), and with an oxygen fugacity above the NNO buffer indicating crystallization from a relatively oxidized magma. U-Pb SHRIMP zircon age data constrain crystallization at ca. 75 Ma. These results confirm magmatic arc activity in the Cordillera Real during the Late Cretaceous, prior to the accretion of the Caribbean oceanic plateau.