Black Shales

I'm a bit puzzled on the comment 'black shales with Zn, Ag and V background'
Is this based on the fact that we have these black shales? Either from previous drilling, or are at surface?
If the deposit is going to be large, one would hope there is a surface geochemical signature. Unless of course there is a massive ground cover of transported material?
Anyway, I am hopeful for good results, but would have liked to see that there is some Zn, Ag or any base metals, etc at the surface in a geochemical survey.
Looking forward to the outcome.