Bimodal volcanism Bimodal volcanism Bimodal volcanism is the eruption of both mafic and felsic lavas from a single volcanic centre with little or no lavas of intermediate composition. This type of volcanism is normally associated with areas of extensional tectonics, particularly rifts. Most occurrences of bimodal volcanism are associated with thinning of the crust and the presence of such rocks in metamorphic sequences has been used to provide evidence for past rifting events. Most examples come from areas of active continental rifting such as the Basin and Range Province. Bimodal volcanism has also been described from areas of transtension, the early phases
Blake River Megacaldera Complex respect to both hydrothermal Cu-Zn massive sulfides and gold-rich massive sulfides. The Blake River Megacaldera Complex consists of mainly mafic to intermediate volcanic flows and less abundant felsic volcanic flows and intercalated pyroclastic rocks, which underwent three stages of major volcanic activity. The Blake River Megacaldera Complex is considered a supervolcano due to its great size and its multiple dikes and vents. The Misema Caldera is in the order of , making the complex similar to the Yellowstone Caldera in Wyoming, Lake Toba in Indonesia and strikingly similar in structure to the Olympus Mons caldera on Mars. As a result,