What geologic processes helped to form gold ore, oil, and aquifers?

Placer deposits are formed by alluvial processes within rivers and streams, and on beaches. Placer gold deposits form via gravity, with the density of gold causing it to sink into trap sites within the river bed, or where water velocity drops, such as bends in rivers and behind boulders.

No single geologic process did all those things. Gold is an element, a heavy element, so it accumulates in seams of hard rocks, quartz being most common. It accumulates over thousands of year