AbstractThe trap rocks have been studied at diamond-bearing regions within the eastern wall of the Tunguska Syneclise. The composition and structural features of pyroclastic rocks of a basaltic complex have been studied on the basis of lithotectonic analysis. The main volume of explosive volcanic rocks is composed of variously clastic tuffs. Their areal occurrence is related to epicenters of interpreted volcanic structures, which are a negative factor during diamond prospecting. The presence of arched intrusive plutons within the paleovalleys and kimberlite-controlling grabens is desirable during prospecting of new primary and placer diamond deposits.