Abstract
Fluid and Metal Sources in Archean Orogenic Gold Deposits
Fluid and Metal Sources in Archean Orogenic Gold Deposits
The Source of Fluid and Metals in Archean Orogenic Gold Deposits
International Applied Geochemistry Symposium, Adelaide 15/10/2024
In this presentation, I show evidence that;
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Archean greenstone-hosted gold systems are mineralogically and geochemically zoned when observed at the scale of a gold "camp".
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Orogenic gold veins were formed within the footprints of rock volumes that were hydrothermally altered prior to metamorphism.
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The early hydrothermal systems were formed at very shallow crustal levels and would have been dominated by hydrous phyllosilicate minerals.
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Metamorphic fluid and ore metals were locally derived and have moved over distances of tens to hundreds of meters.
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Molar element ratios allow us to "see through" the metamorphism.
If you are looking at the Powerpoint file, also follow the notes pages, as there is extra descriptions in here that you won't see in presentation mode.
Abstract
Pathfinder Footprints of Eastern Australian Mineral Deposits
Pathfinder Footprints of Eastern Australian Mineral Deposits.
Mines and Wines "Discoveries in the Tasmanides", 06/09/2024
To measure a pathfinder element footprint, we need an analytical method that measures an element at least down to the far field background level, ie average crustal abundance. It is only since the widespread uptake of ICP-MS that we have been able to achieve that. During the 1960’s, 70’s and 80’s, lots of new deposits were discovered via geochemical surveys with direct detection of the target metal. I think we have failed to make effective use of pathfinder geochem from ICP-MS data because the patterns of element dispersion are not adequately documented in public domain literature.
In this presentation, I give an example of the geochemical footprint of a porphyry copper system, a low sulfidation epithermal district (Pajingo) and a VMS district (Hellyer). If you are looking at the Powerpoint file, also follow the notes pages, as there is extra descriptions in here that you won't see in presentation mode.
Applied Lithogeochemistry
in the Eastern Goldfields
Applied Lithogeochemistry in the Eastern Goldfields
Big Day Out Symposium 20/03/2023
This is my presentation given at the Kalgoorlie "Big Day Out" on 20/03/2023, sponsored by Raglan Drilling and the Geological Survey of Western Australia. I have added lots of text in the notes page to help explain my thoughts, so display this in a powerpoint mode where you can read the notes below the slide page.
Advances in Exploration Geochemistry
Sydney Mineral Exploration Discussion Group (SMEDG), 25/08/2022
This is my presentation given at the 50th anniversary of the Sydney Mineral Exploration Discussion Group (SMEDG) on 25th August, 2022. The invited theme was to discuss the most significant advances in geochemistry in recent time, but also to reflect on how we use our data, and what things we need to do better. I added a brief case study on how routine exploration data, collected by 4 acid digest ICP-MS, can inform us about geological processes; in this case the evolution of alkalic magmas associated with gold rich porphyry systems. I have added lots of text in the notes page to help explain my thoughts, so don't just view in slideshow mode.
Magmatic Geochemistry for Exploration Geologists
"Geohug" Webinar from 26th February 2021
This powerpoint point file was from a webinar sponsored by ALS on 25th February 2021. It introduces some basics about assay methods, QAQC, databases, and interpretation of data. This is some useful reading matter to go through before starting the "teach yourself" tutorials.
How to Make the Most of Your Multielement Geochemistry
AusIMM Pacrim, Auckland 04/04/2019