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| DOI | 10.1007/S00126-024-01259-2 | ||||
| Año | 2024 | ||||
| Tipo | artículo de investigación |
Citas Totales
Autores Afiliación Chile
Instituciones Chile
% Participación
Internacional
Autores
Afiliación Extranjera
Instituciones
Extranjeras
The Punta del Cobre district near Copiapo is a center of iron oxide-copper-gold (IOCG) mineralization spatially and temporally associated with regional sodic-calcic hydrothermal alteration, the Atacama fault system (AFS), and two phases of Early Cretaceous magmatism. Here, we investigate the spatiotemporal and geochemical relationships between magmatism, ductile deformation, and hydrothermal alteration along the similar to 200 to 300-m-thick steeply NW-dipping Sierra Chicharra shear zone, interpreted to be the major strand of the AFS. Mylonitic fabrics and oblique sinistral-reverse kinematic indicators together record coaxial flattening in a transpressional regime. Deformation on the AFS took place before, during, and after intrusion of the synkinematic Sierra Chicharra quartz diorite of the Coastal Cordillera arc at similar to 122 Ma and terminated before intrusion of the unstrained similar to 114 Ma Sierra Atacama diorite of the Copiapo batholith. Geochemical data show that the Copiapo batholith was more mafic and more K-rich than the calc-alkaline Coastal Cordillera arc. This time period thus overlaps IOCG mineralization in the Punta del Cobre district (similar to 120 to 110 Ma). Multiple phases of sodic-calcic alteration in and around the AFS shear zone are recognized. Textures of altered rock in the shear zone show both synkinematic assemblages and post-kinematic hydrothermal oligoclase. A similar to 775-m-long andradite vein that cuts the shear zone formed broadly at the end of magmatism in the district (similar to 95 Ma). Oxygen isotope ratios from the vein indicate that hydrothermal fluids were likely magmatically derived. Together, this work shows the AFS-related shear zone and nearby IOCG mineralization developed in a regional transpressional regime produced by SE-directed oblique convergence across a NE-striking shear zone. IOCG-related magmatic-hydrothermal fluids exploited this transcrustal shear zone to produce multiple episodes of regional sodic-calcic alteration formed from fluids exsolved from magmas or driven by the heat of the Coastal Cordillera arc and Copiapo batholith.
| Ord. | Autor | Género | Institución - País |
|---|---|---|---|
| 1 | Seymour, N. M. | Mujer |
COLORADO STATE UNIV - Estados Unidos
Universidad de Stanford - Estados Unidos Occidental Coll - Estados Unidos Stanford University - Estados Unidos Colorado State University - Estados Unidos Occidental College - Estados Unidos |
| 2 | Singleton, J. S. | Hombre |
COLORADO STATE UNIV - Estados Unidos
Colorado State University - Estados Unidos |
| 3 | Gomila, Rodrigo | Hombre |
Pontificia Universidad Católica de Chile - Chile
Univ Padua - Italia Università degli Studi di Padova - Italia |
| 4 | ARANCIBIA-HERNANDEZ, GLORIA CECILIA | Mujer |
Pontificia Universidad Católica de Chile - Chile
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| 5 | Ridley, John | Hombre |
COLORADO STATE UNIV - Estados Unidos
Colorado State University - Estados Unidos |
| 6 | Gevedon, M. L. | - |
Colorado Coll - Estados Unidos
Colorado College - Estados Unidos |
| 7 | Stockli, Daniel F. | Hombre |
Univ Texas Austin - Estados Unidos
The University of Texas at Austin - Estados Unidos |
| 8 | Seman, S. M. | - |
Univ Texas Austin - Estados Unidos
The University of Texas at Austin - Estados Unidos |
| Fuente |
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| National Science Foundation |
| Directorate for Geosciences |
| SCELC |
| Millennium Nucleus Center for Metal Tracing Along Subduction NC |
| Agradecimiento |
|---|
| The authors would like to thank M. Hernandez for field assistance, D. Adams for SEM assistance at USGS Denver, D. Burns for EMPA assistance at Stanford, and L. Stockli for laboratory assistance at UT-Austin. G. Heuser, Y. Kuiper, J. Hourigan, M. Grove, A. Pamucku, and J. Barnes are thanked for helpful discussions. The authors would like to thank N. Jansson, F. Tornos, N. Oliver, J. Andersson, and two anonymous reviewers for their detailed and constructive feedback on this manuscript. |
| Open access funding provided by SCELC, Statewide California Electronic Library Consortium This work was funded by National Science Foundation Grant #1822064 to J. Singleton and Society of Economic Geologists Student Research Grant to N. Seymour. G. Arancibia acknowledges funding from Millennium Nucleus Center for Metal Tracing Along Subduction NC #130065. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award ECCS-2026822. |