A positive fold test from Nipissing diabase

Positive fold tests are reported on two remanence components resolved from the same Nipissing diabase sills. These tests conclusively indicate that the region south of the Sudbury Basin in the Southern Structural Province has been subjected to two distinct deformational episodes subsequent to the intrusion of the Nipissing diabase. One event precedes (1850–2150 Ma) and one event postdates (1250–1850 Ma) intrusion of the Sudbury irruptive. Some …