The felsic rocks of the Mashavera and Gasandami Suites were deposited during a ~6.6 m.y.-long silicic magmatic flare-up event, which together with the Tandzia Suite mafic rocks, documents Late Cretaceous bimodal magmatism in an extensional tectonic setting. The Mashavera and Gasandami rhyolite and dacite have yielded U-Pb LA-ICP-MS and TIMS zircon ages between 87.14 ± 0.16 and 81.64 ± 0.94 Ma, which are in line with the Coniacan-Santonian ages of radiolarian fauna of the Mashavera Suite.
Late Cretaceous, low-K, calc-alkaline to high-K rhyolite of the Mashavera and Gasandami Suites is the predominant rock type of the district, and is accompanied by subsidiary dacite, and rare high-alumina basalt and trachyandesite of the Tandzia Suite. The Bolnisi district is a distinct tectonic zone of the Lesser Caucasus, which is considered to represent the eastern extremity of the Turkish Eastern Pontides.
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