1967/ 1976
If you search the Black Metal band more close to Thrash metal sure Immortal is your band. "Immortal" Ep is a 7" Ep compiled with intro and two songs. The style is, not only in my view, a sort of mix between German Thrash Metal (Sodom, Destruction) and pure Black Metal (Venom, in first plan [if Venom is Black Metal] and Necrodeath) and also in some moment with Industrial sound and style. The final result is a sort of Black Thrash metal extremely evocative and not easy to listen to, due to tempo changes and Prog Metal final feeling.
The sound is poor, but because in 1991 this is the sound of Black Metal. The drums sound remember me first Grave Digger album or first albums of Helloween or Necrodeath but the obscure mix reduces the weight of drums.
In definitive if you search the origins of Thrash Black Metal and if German Thrash metal please you Immortal is you band and if you search the origins of Immortal this 7" Ep is a great purchase.