Metamorphic evidence of early post-Bushveld sills in the Penge iron formation, Transvaal sequence, eastern Transvaal.

Mafic ("diabase') sills present in the Penge iron formation in the eastern Transvaal at Penge belong to the amphibolitic group of sills which are generally considered to be older than the Bushveld complex. The present investigation, however, suggests that this assumption may be invalid and that these sills post-date the peak metamorphic episode related to the intrusion of the Bushveld complex. This interpretation is based on the observation that a hornblende-clinopyroxene-fayalite-bearing contact metamorphic assemblage overprints a Bushveld-related grunerite-bearing metamorphic assemblage immediately adjacent to these sills. (Authors' abstract)-A.W.H.