31 CRITICAL MINERAL DEPOSITS AND ORE SYSTEMS OF THE NORTHEAST (Poster)

This session will showcase new findings pertaining to critical mineral resources and hydrothermal-magmatic ore systems across the northeast. We welcome submissions involving fieldwork, geochemical, petrologic, geochronologic, and other approaches from micro- to macroscopic scales.

Monday, 23 March 2026
1:30 PM - 5:30 PM
CCC, Ballroom C

Source Region and Partitioning of Gold in Magmatic Systems

Paper number: 31-3
Program: Technical Sessions
Time: 1:30 PM – 1:30 PM

Authors

Abstract

As global demand for metals surges due to the transition to renewable energy technologies, understanding the formation of hydrothermal gold deposits is crucial for identifying new deposits. While economic gold concentrations often occur as shallow epithermal deposits (<3 km), the parent magmas originate in significantly deeper source regions (>15 km). Prior experimental research largely focused on low-pressure depositional environments, leaving the controls on gold incorporation uncertain. This study investigates gold solubility and partitioning between granitic melts and coexisting hydrothermal fluids across a broad pressure range (1–10 kbar) to simulate the journey from deep source regions to the upper crust, where viable deposits form. This study aims to resolve longstanding questions regarding whether magmas "scavenge" gold during transport or inherit it from gold-rich source regions. 

Samples were synthesized in a dual piston-cylinder apparatus for higher pressure experiments and a cold-seal pressure vessel for lower pressures. Experimental conditions were repeated with both native gold and AuCl3 to evaluate the impact of salinity on gold partitioning. Experiments utilized a granitic obsidian starting material and fractured quartz wafers to trap fluid inclusions. Gold is sequestered into vapor bubbles within vesiculated melt and trapped as multiphase fluid inclusions as the experiment is quenched. Quantitative analysis via electron probe microanalysis (EPMA) and fluid inclusion microthermometry was used to calculate partition coefficients. Future work will use Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICPMS) to directly measure the gold concentration of the fluid inclusions. 

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411344

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