Circum-Superior Belt northwestern Superior craton margin intrude an older, 2,090 to 2,070 million-year-old dike swarm. The Ospwagan Group is younger than and the 1,864 million-year-old Winnipegosis komatiite belt lies to the southwest. Numerous tectonic settings have been suggested for triggering magmatism in the Fox River Belt, including a marginal basin rifting event. At the southern portion of the Circum-Superior Belt, a group of fragmental sediments composed of iron formation was formed during a period of magmatic activity in the Marquette Range Supergroup. Included in the Marquette Range Supergroup is the Hemlock Formation, a bimodal volcanic group that is estimated to have an
Ring of Fire (1991 film) Ring of Fire (1991 film) Ring of Fire is a 1991 documentary film in IMAX format. It looks at some of the varieties of volcanism and earthquake activity in the Ring of Fire, around the Pacific Rim. The film runs 40 minutes. The film was jointly presented by the Fort Worth Museum of Science and History in Fort Worth, Texas, the Science Museum of Minnesota in Saint Paul, Minnesota, and the Reuben H. Fleet Space Theater and Science Center in San Diego, California. The film has eight main segments, corresponding to chapters in the DVD release: 1. "Ring of Fire":