Magnetic and Paleomagnetic Studies of the Nipissing Diabase, Lake Matinenda Area, Ontario

Abstract

Samples of the Nipissing diabase were collected for rock-magnetic and paleomagnetic studies around and west of Lake Matinenda, Ontario. The specimens have been classified into three groups, based on their stability of natural remanent magnetism, using the alternating field demagnetization technique.Opaque petrological studies showed that the specimens which possessed magnetite–ilmenite exsolution were magnetically very stable. The specimens without any exsolution possessed weak and unstable magnetization.Sphene was identified in the alteration product of ilmenite using X-ray techniques. Curie point measurements indicated low titanium content in the specimens which contained exsolution of ilmenite in magnetite.The pole position, calculated from five significant sites located around and west of Lake Matinenda is 69.9 °W, 15.6 °S (A95 = 6.1°).