Volcano-Sedimentary and Hydrothermal Bentonite Deposits.

This paper is a study of volcanogenic bentonite. We examine the geological structural settings of the deposits, the paleogeographic environment of sedimentation, structural and textural features of the rocks, and their diagnostic features. We have identified ore-controlling factors in the generation of volcanogenic and hydrothermal bentonite. Comparative analysis has been performed of the original volcanogenic material sampled at deposits in Russia and abroad. The Dash-Salakhly deposit (Republic of Azerbaijan) and a bentonite-bearing province on Sakhalin Island were studied to find how bentonites of different genesis were formed. These studies provide evidence that the composition of the parent material for bentonite varies in a wide range, between basalt and rhyolite. The main factor that controls the generation of bentonite is the type of the sedimentation basin and physicochemical conditions rather than the composition of the parent material. [ABSTRACT FROM AUTHOR]