Thursday, 9 November 2017

Mafic dykes cross cut a granite

Mafic (basalt) dykes cross cut thegranite of the Burnside Batholith at Lowlands Beach.

I was very taken with the two planes of weakness highlighted here by right angled jogs in the intruding dyke. The locations where the dykes, which are around 25cm wide, pinch out and step across suggest to me a more sheared or rotational strain field.