Circum-Superior Belt event in Australia and 1,860 million year old magmatism of the Mashonaland event in Africa. The other questionable suggestion related to the Circum-Superior Belt is the existence of a suggested 1,900 million year old global superplume event. The long Labrador Trough, extending from Ungava Bay through Quebec and Labrador, includes two volcano-sedimentary series, the first ranging from 2,170 to 2,140 million years old and second ranging from 1,883 to 1,870 million years old. This magmatism is considered to have formed as a result of back-arc volcanism. The youngest magmatic series (1883-1870 Ma) contains 1,880 million-year-old carbonatites and lamprophyres. 1,883 to
Circum-Superior Belt extend over across the western portion of the Superior craton from near the Fox River Belt in the north to near Lake Superior in the south. This magmatic crossing creates a relationship with the 1,880 million-year-old magmatism in the northwestern portion of the Circum-Superior Belt and magmatism in the Marguette Range Supergroup on the southern portion of the Circum-Superior Belt. In addition, the north-northwest trend of the Pickle Crow dikes and the absolute north-northeastern trend of the Molson dike swarm combine to an area north of the northwestern portion of the Circum-Superior Belt. This might determine the zone of a