The Interplay of Evolved Seawater and Magmatic-Hydrothermal Fluids in the 3.24 Ga Panorama Volcanic-hosted Massive Sulfide Hydrothermal System, North Pilbara Craton, Western Australia  


Authors / CoAuthors

Drieberg, S.L. | Hagemann, S. | Huston, D.L. | Landis, G. | Ryan, C.G. | van Achterbergh, E. | Vennemann, T.

Abstract

In addition to typical seafloor VHMS deposits, the ~3240 Ma Panorama district contains contemporaneous greisen- and vein-hosted Mo-Cu-Zn-Sn occurrences that hosted by the Strelley granite complex, which drove VHMS circulation. High-temperature alteration zones in volcanic rocks underlying the VHMS deposits are dominated by quartz-chlorite±albite assemblages, with lesser low-temperature quartz-sericite±K-feldspar assemblages, typical of VHMS hydrothermal systems. Alteration assemblages associated with granite-hosted greisens and veins, which do not extend into the overlying volcanc pile, include quartz-topaz-muscovite-fluorite and quartz-muscovite(sericite)-chlorite-ankerite. Fluid inclusion and stable isotope data suggest that the greisens formed from high temperature (~590C), high salinity (38-56 wt % NaCl equiv) fluids with high densities (>1.3 g/cm3) and high -18O (9.3±0.6-), which are compatible with magmatic fluids evolved from the Strelley granite complex. Fluids in the volcanic pile (including the VHMS ore-forming fluids) were of lower temperature (90-270C), lower salinity (5.0-11.2 wt % NaCl equiv), with lower densities (0.88-1.01 g/cm3) and lower -18O (-0.8±2.6), compatible with evolved Paleoarchean seawater. Fluids that formed the quartz-chalcopyrite-sphalerite-cassiterite veins, which are present within the upper granite complex, were intermediate in temperature and isotopic composition (T = 240-315C; -18O = 4.3±1.5-) and are interpreted to indicate mixing between the two end-member fluids. Evidence of mixing between evolved seawater and magmatic-hydrothermal fluid in the granite complex, along with a lack of evidence for a magmatic component in fluids from the volcanic pile, suggest partitioning of magmatic-hydrothermal from evolved seawater hydrothermal systems in the Panorama VHMS system, interpreted as a consequence swamping of the system by evolved seawater or density contrasts.

Product Type

nonGeographicDataset

eCat Id

69971

Contact for the resource

  Custodian

MNHD  

  Point of contact

Commonwealth of Australia (Geoscience Australia)  
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia

Keywords

  • External Publication
( Theme )
  • alteration
( Theme )
  • depositional mechanisms
( Theme )
  • economic geology
( Theme )
  • fluid flow drivers
( Theme )
  • fluid flow pathways
( Theme )
  • fluid inclusions
( Theme )
  • geochemistry
( Theme )
  • geology
( Theme )
  • isotopes
( Theme )
  • metallogenesis
( Theme )
  • mineral deposits
( Theme )
  • salinity
( Theme )
  • fluid reservoirs
  • AU-WA
Australian and New Zealand Standard Research Classification (ANZSRC)
  • Earth Sciences
  • Published_Internal

Publication Date

2009-12-16T00:00:00

Creation Date

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Australian Government Security ClassificationSystem    

Classification - unclassified

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Creative Commons Attribution 4.0 International Licence    

Access - restricted

Use - license

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Purpose

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unknown

Topic Category

geoscientificInformation

Series Information

Lineage

Unknown

Parent Information

Extents

[-21.5, -21.0, 119.0, 119.5]

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