Vein- or Fissure- Filling Deposits of Native Gold and Silver

Multiple Choice

Vein- or fissure- filling deposits of native gold and silver, or copper and zinc sulphides, would be more common in _________.

A) hydrothermally fractured rocks in the contact- metamorphic zone formed above a shallow felsic pluton like the setting at Yellowstone
B) in limestone dissolution and collapse breccias such as occur at Pine Point, NWT
C) rocks formed deep in a layered magma chamber like the Bird River Sill in Manitoba
D) in faults, impactites, and shattered rock of a meteorite impact zone like Sudbury