Carlin-type gold deposits hold up to about 9,000 parts per million gold in pyrite, invisible to the eye, hand lens, or pan, in gray silty limestone a forty-niner would have walked past. Four unrelated events built them: a reactive continental shelf, a mountain-building thrust, a brief Eocene fluid pulse, and later uplift. Where the gold came from is still argued.
Who's who
- Albert HofstraGeologist; co-author of the 2005 synthesis
- John Muntean+1 more episodeGeologist; proponent of the magmatic-hydrothermal model
- Christopher HenryGeologist who dated the most precisely dated Nevada deposit
- Victoria GrauchUSGS geophysicist who mapped deep crustal fault zones
- Meng ChaiLead author of a May 2026 paper placing the gold in host rocks
- Anthony Williams-JonesCo-author of the 2026 sedimentary-source paper
Where it happens
- Cortez Hills, NevadaMost precisely dated Carlin-type deposit, about 35.7 million years
- Roberts Mountains, NevadaThrust that stacked deep-water rock over the shelf
- Carlin Trend, NevadaCorridor of Eocene dikes and gold deposits
- Youjiang Basin, southwestern ChinaSecond-largest Carlin-type goldfield, a distant second
Timeline
- Late Devonian-Early MississippianThe Antler Orogeny thrusts deep-water rock eastward over the shelf.
- c. 42.5 million years agoEarliest dated Carlin-type mineralization in northern Nevada, at Twin Creeks.
- c. 35.7 million years agoCortez Hills forms, possibly within about 45,000 years.
- 16-10 million years agoMiddle Miocene extension tilts the deposits into reach.
- May 13, 2026A paper argues the gold was already in the host rocks.
Still debated
The source of the fluid and gold is unsettled: magmatic, deep metamorphic, meteoric water, or sedimentary rocks with only magmatic heat. Nobody disputes the Eocene timing, and why such deposits are concentrated almost only in Nevada is a conjunction of conditions, not a settled mechanism.