| At depth, some kimberlite breccias grade into root zones of dikes made of unfragmented rock. |
| Basement rocks consist of Tortonian volcanic rocks unconformably overlain by Messinian marine marls, coral-reef limestones and carbonate breccias. |
| In these types of deposits, gold and silver are precipitated by hot springs in fissures, faults, and explosive breccias in the upper portions of the mineral system. |
| These eruptions deposited pebble-grade volcaniclastic breccias of an intermediate composition within a few kilometres of the Rio Tinto Anticline. |
| The mafic sheets have not contributed at all to the felsic volcanic-derived volcaniclastic breccias, thus supporting an intrusive origin for the mafic volcanic rocks. |
| They consist of intrusive materials, breccias, tuffs and massive peripheral lava flows. |
