Gold veins are formed when hot, gold-rich fluids move through cracks in the Earth's crust. As the fluids cool, the gold precipitates out of the solution and forms veins.

Scientists have long been trying to understand how these fluids move through the crust. One theory is that they are driven by convection, like the currents in a pot of boiling water. Another theory is that they are driven by pressure gradients, like the flow of water through a pipe.

A new study by researchers at the University of Alberta provides evidence to support the convection theory. The researchers studied the composition of gold veins in the Abitibi Greenstone Belt in Canada. They found that the veins are consistently oriented in a vertical direction, suggesting that they were formed by hot fluids rising from deep in the Earth.

The researchers also found that the veins are associated with areas of altered rock. The alteration is caused by the interaction of the hot fluids with the surrounding rock. This alteration is similar to the souring of milk, which is caused by the interaction of bacteria with the milk.

The researchers believe that the alteration of the rock around the gold veins is the key to understanding how the veins form. They propose that the alteration creates a pathway for the hot fluids to move through the crust. The fluids then rise through the pathway and deposit the gold as they cool.

The study provides new insights into the formation of gold veins. The findings could help geologists explore for gold deposits more effectively.

Source: University of Alberta