Originally Posted by El Gordo
I don't care if Cliff Burton came back from the dead and told me that Destruction EP isn't thrash... it's fucking thrash. Was it important to the fledgling black metal movement at that time? Yes, but it's thrash, especially in 1984.
Exactly. The first wave encompasses a number of different styles. When people call the early teutonic thrash records black metal, it's really just a loose term for the combination of imagery, lyrics, and production values that would later influence the second wave. It's not a genre, but more of an era of bands that have similarities without a definitive sound.