View in EDS

Sodic-calcic alteration and transpressional shear along the Atacama fault system during IOCG mineralization, Copiapó, Chile.

Saved in:
Bibliographic Details
Title: Sodic-calcic alteration and transpressional shear along the Atacama fault system during IOCG mineralization, Copiapó, Chile.
Authors: Seymour, N. M.1,2,3 (AUTHOR) nseymour@oxy.edu, Singleton, J. S.1 (AUTHOR), Gomila, R.4,5 (AUTHOR), Arancibia, G.4 (AUTHOR), Ridley, J.1 (AUTHOR), Gevedon, M. L.6 (AUTHOR), Stockli, D. F.7 (AUTHOR), Seman, S. M.7 (AUTHOR)
Source: Mineralium Deposita. Oct2024, Vol. 59 Issue 7, p1295-1323. 29p.
Subject Terms: *Shear zones, *Hydrothermal alteration, *Tonalite, *Oxygen isotopes, *Rock texture
Abstract: The Punta del Cobre district near Copiapó 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 ~ 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 ~ 122 Ma and terminated before intrusion of the unstrained ~ 114 Ma Sierra Atacama diorite of the Copiapó batholith. Geochemical data show that the Copiapó 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 (~ 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 ~ 775-m-long andradite vein that cuts the shear zone formed broadly at the end of magmatism in the district (~ 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 Copiapó batholith. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
FullText Text:
  Availability: 0
Header DbId: enr
DbLabel: Energy & Power Source
An: 179460571
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
IllustrationInfo
Items – Name: Title
  Label: Title
  Group: Ti
  Data: Sodic-calcic alteration and transpressional shear along the Atacama fault system during IOCG mineralization, Copiapó, Chile.
– Name: Author
  Label: Authors
  Group: Au
  Data: <searchLink fieldCode="AR" term="%22Seymour%2C+N%2E+M%2E%22">Seymour, N. M.</searchLink><relatesTo>1,2,3</relatesTo> (AUTHOR)<i> nseymour@oxy.edu</i><br /><searchLink fieldCode="AR" term="%22Singleton%2C+J%2E+S%2E%22">Singleton, J. S.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Gomila%2C+R%2E%22">Gomila, R.</searchLink><relatesTo>4,5</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Arancibia%2C+G%2E%22">Arancibia, G.</searchLink><relatesTo>4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Ridley%2C+J%2E%22">Ridley, J.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Gevedon%2C+M%2E+L%2E%22">Gevedon, M. L.</searchLink><relatesTo>6</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Stockli%2C+D%2E+F%2E%22">Stockli, D. F.</searchLink><relatesTo>7</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Seman%2C+S%2E+M%2E%22">Seman, S. M.</searchLink><relatesTo>7</relatesTo> (AUTHOR)
– Name: TitleSource
  Label: Source
  Group: Src
  Data: <searchLink fieldCode="JN" term="%22Mineralium+Deposita%22">Mineralium Deposita</searchLink>. Oct2024, Vol. 59 Issue 7, p1295-1323. 29p.
– Name: Subject
  Label: Subject Terms
  Group: Su
  Data: *<searchLink fieldCode="DE" term="%22Shear+zones%22">Shear zones</searchLink><br />*<searchLink fieldCode="DE" term="%22Hydrothermal+alteration%22">Hydrothermal alteration</searchLink><br />*<searchLink fieldCode="DE" term="%22Tonalite%22">Tonalite</searchLink><br />*<searchLink fieldCode="DE" term="%22Oxygen+isotopes%22">Oxygen isotopes</searchLink><br />*<searchLink fieldCode="DE" term="%22Rock+texture%22">Rock texture</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The Punta del Cobre district near Copiapó 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 ~ 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 ~ 122 Ma and terminated before intrusion of the unstrained ~ 114 Ma Sierra Atacama diorite of the Copiapó batholith. Geochemical data show that the Copiapó 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 (~ 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 ~ 775-m-long andradite vein that cuts the shear zone formed broadly at the end of magmatism in the district (~ 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 Copiapó batholith. [ABSTRACT FROM AUTHOR]
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=enr&AN=179460571
RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1007/s00126-024-01259-2
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 29
        StartPage: 1295
    Subjects:
      – SubjectFull: Shear zones
        Type: general
      – SubjectFull: Hydrothermal alteration
        Type: general
      – SubjectFull: Tonalite
        Type: general
      – SubjectFull: Oxygen isotopes
        Type: general
      – SubjectFull: Rock texture
        Type: general
    Titles:
      – TitleFull: Sodic-calcic alteration and transpressional shear along the Atacama fault system during IOCG mineralization, Copiapó, Chile.
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Seymour, N. M.
      – PersonEntity:
          Name:
            NameFull: Singleton, J. S.
      – PersonEntity:
          Name:
            NameFull: Gomila, R.
      – PersonEntity:
          Name:
            NameFull: Arancibia, G.
      – PersonEntity:
          Name:
            NameFull: Ridley, J.
      – PersonEntity:
          Name:
            NameFull: Gevedon, M. L.
      – PersonEntity:
          Name:
            NameFull: Stockli, D. F.
      – PersonEntity:
          Name:
            NameFull: Seman, S. M.
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 10
              Text: Oct2024
              Type: published
              Y: 2024
          Identifiers:
            – Type: issn-print
              Value: 00264598
          Numbering:
            – Type: volume
              Value: 59
            – Type: issue
              Value: 7
          Titles:
            – TitleFull: Mineralium Deposita
              Type: main
ResultId 1