A Record of Tectonic Plumbing
Deep within Myanmar's Sagaing Region, the earth's crust holds a detailed record of ancient hydrothermal activity. The Yinmabin deposits consist of countless veins of antimony ore that fill a network of fractures in the surrounding rock. These deposits were formed when superheated, mineral-rich water, driven by tectonic forces, forced its way up from deep within the earth. As these fluids traveled through cracks in older sedimentary rocks, they cooled and precipitated their dissolved mineral load. The result is a complex, three-dimensional network of ore that maps the exact pathways the fluids took millions of years ago.
The primary host rocks belong to the Pane Chaung Formation, a thick sequence of turbidites—sediments deposited by ancient underwater landslides. This formation dates back to the Late Triassic period, between 233 and 206 million years ago. The tectonic activity that created the fractures and provided the heat for mineralization is linked to the ongoing collision of the Indian and Eurasian plates. This immense geological pressure cracked the crust, allowing magmatic heat to drive the circulation of hydrothermal fluids at temperatures between 140 and 260 °C. These fluids dissolved metals from a deep source and carried them upwards. As the fluids ascended into cooler rock, the change in temperature and pressure caused the dissolved elements to crystallize, filling the fissures with a metallic bounty.