Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia
Establishing timescales for iron oxide copper-gold (IOCG) deposit formation and the temporal relationships between ores and the magmatic rocks from which hydrothermal, metal-rich fluids are sourced is often dependent on low-precision data, particularly for deposits that formed during the Proterozoic...
| Main Authors: | , , , , , , , , |
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| Format: | Journal Article |
| Published: |
Society of Economic Geologists
2020
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| Online Access: | http://purl.org/au-research/grants/arc/IH130200033 http://hdl.handle.net/20.500.11937/81955 |
| _version_ | 1848764452591108096 |
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| author | Courtney-Davies, Liam Ciobanu, Cristiana Tapster, Simon Cook, Nigel Ehrig, Kathy Crowley, James Verdugo-Ihl, Max Wade, Benjamin Condon, Daniel |
| author_facet | Courtney-Davies, Liam Ciobanu, Cristiana Tapster, Simon Cook, Nigel Ehrig, Kathy Crowley, James Verdugo-Ihl, Max Wade, Benjamin Condon, Daniel |
| author_sort | Courtney-Davies, Liam |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Establishing timescales for iron oxide copper-gold (IOCG) deposit formation and the temporal relationships between ores and the magmatic rocks from which hydrothermal, metal-rich fluids are sourced is often dependent on low-precision data, particularly for deposits that formed during the Proterozoic. Unlike accessory minerals routinely used to track hydrothermal mineralization, iron oxides are dominant components of IOCG systems and are therefore pivotal to understanding deposit evolution. The presence of ubiquitous, magmatic-hydrothermal U-(Pb)-W-Sn-Mo–bearing zoned hematite resolves a range of geochronological issues concerning formation of the ~1.6 Ga Olympic Dam IOCG deposit, South Australia, at up to ~0.05% precision (207Pb/206Pb weighted mean; 2σ) using isotope dilution-thermal ionization mass spectrometry (ID-TIMS). Coupled with chemical abrasion-ID-TIMS zircon dates from host granite and volcanic rocks within and enclosing the ore-body, a confident magmatic-hydrothermal chronology is defined. The youngest zircon date from the granite intrusion hosting Olympic Dam indicates magmatism was occurring up until 1593.28 ± 0.26 Ma. The orebody was principally formed during a major mineralizing event following granite uplift and during cupola collapse, whereby the hematite with the oldest age is recorded in the outer shell of the deposit at 1591.27 ± 0.89 Ma, ~2 m.y. later than the youngest documented magmatic zircon. Hematite dates captured throughout major lithologies, different ore zones, and the ~2-km vertical extent of the deposit support ~2 m.y. of hydrothermal activity. New age constraints on the spatial-temporal evolution of the formation of Olympic Dam are considered with respect to a mantle to crustal continuum model. Cyclical tapping of magma reservoirs to maintain crystal mushes for extended time periods and incremental building of batholiths on the million-year scale prior to main mineralization pulses can explain the ~2-m.y. temporal window temporal window inferred from the data. Despite the challenge of reconciling such an extended window with contemporary models for porphyry deposits (≤1 m.y.), formation of Proterozoic ore deposits has been addressed at high-precision and supports the case that giant IOCG deposits may form over millions of years. |
| first_indexed | 2025-11-14T11:19:35Z |
| format | Journal Article |
| id | curtin-20.500.11937-81955 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T11:19:35Z |
| publishDate | 2020 |
| publisher | Society of Economic Geologists |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-819552021-02-22T01:24:38Z Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia Courtney-Davies, Liam Ciobanu, Cristiana Tapster, Simon Cook, Nigel Ehrig, Kathy Crowley, James Verdugo-Ihl, Max Wade, Benjamin Condon, Daniel Establishing timescales for iron oxide copper-gold (IOCG) deposit formation and the temporal relationships between ores and the magmatic rocks from which hydrothermal, metal-rich fluids are sourced is often dependent on low-precision data, particularly for deposits that formed during the Proterozoic. Unlike accessory minerals routinely used to track hydrothermal mineralization, iron oxides are dominant components of IOCG systems and are therefore pivotal to understanding deposit evolution. The presence of ubiquitous, magmatic-hydrothermal U-(Pb)-W-Sn-Mo–bearing zoned hematite resolves a range of geochronological issues concerning formation of the ~1.6 Ga Olympic Dam IOCG deposit, South Australia, at up to ~0.05% precision (207Pb/206Pb weighted mean; 2σ) using isotope dilution-thermal ionization mass spectrometry (ID-TIMS). Coupled with chemical abrasion-ID-TIMS zircon dates from host granite and volcanic rocks within and enclosing the ore-body, a confident magmatic-hydrothermal chronology is defined. The youngest zircon date from the granite intrusion hosting Olympic Dam indicates magmatism was occurring up until 1593.28 ± 0.26 Ma. The orebody was principally formed during a major mineralizing event following granite uplift and during cupola collapse, whereby the hematite with the oldest age is recorded in the outer shell of the deposit at 1591.27 ± 0.89 Ma, ~2 m.y. later than the youngest documented magmatic zircon. Hematite dates captured throughout major lithologies, different ore zones, and the ~2-km vertical extent of the deposit support ~2 m.y. of hydrothermal activity. New age constraints on the spatial-temporal evolution of the formation of Olympic Dam are considered with respect to a mantle to crustal continuum model. Cyclical tapping of magma reservoirs to maintain crystal mushes for extended time periods and incremental building of batholiths on the million-year scale prior to main mineralization pulses can explain the ~2-m.y. temporal window temporal window inferred from the data. Despite the challenge of reconciling such an extended window with contemporary models for porphyry deposits (≤1 m.y.), formation of Proterozoic ore deposits has been addressed at high-precision and supports the case that giant IOCG deposits may form over millions of years. 2020 Journal Article http://hdl.handle.net/20.500.11937/81955 10.5382/econgeo.4772 http://purl.org/au-research/grants/arc/IH130200033 Society of Economic Geologists restricted |
| spellingShingle | Courtney-Davies, Liam Ciobanu, Cristiana Tapster, Simon Cook, Nigel Ehrig, Kathy Crowley, James Verdugo-Ihl, Max Wade, Benjamin Condon, Daniel Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia |
| title | Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia |
| title_full | Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia |
| title_fullStr | Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia |
| title_full_unstemmed | Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia |
| title_short | Opening the magmatic-hydrothermal window: high-precision U-Pb geochronology of the mesoproterozoic Olympic Dam Cu-U-Au-Ag deposit, South Australia |
| title_sort | opening the magmatic-hydrothermal window: high-precision u-pb geochronology of the mesoproterozoic olympic dam cu-u-au-ag deposit, south australia |
| url | http://purl.org/au-research/grants/arc/IH130200033 http://hdl.handle.net/20.500.11937/81955 |