I have little knowledge of clay petrology so I decided to take some time out and read this article.
This talks about Cow Head Breccia of middle cambrian to late lower ordovician age and the overlying middle ordovician “red shale”. The clay minerals in the Cow Head are illite, mixed-layered illite-smectite, chlorite, expandable chlorite and corrensite. They occur in three clay layered mineral suites named for the dominant clay minerals. The Cow Head Klippe in western Newfoundland contains three stratigraphically restricted suites of clay minerals
Beginning in the early lower ordivician , rich volcanic detritus was transported westward from a developing volcanic arc in central Newfoundland.