Geology and mineralogy of the Novo-Akhmirovskoe deposit of lithium topaz-zinnwaldite granites (East Kazakhstan)

Abstract

Research subject. The Novo-Akhmirovskoe lithium-bearing deposit in the East Kazakhstan region, which is represented by an intrusive layer of topaz-zinnwaldite granites, is located within of the Kalba-Narym-Koktogai lithium-tantalum raremetal-granite belt. Being part of the Altai collision system, this belt is considered unique in terms of its length (more than 1000 km). Ores in the Novo-Akhmirovskoe deposit are represented by massive to low porphyry leucocratic granites composed of quartz (30–40%), albite (25–40%), microcline (15–35%), lithium mica varying in composition from zinnwal dite to lepidolite (up to 10%) and topaz (up to 5%). According preliminary estimates, the Novo-Akhmirov deposit is factually a poor lithium deposit with the Li2O content of 0.2–0.4 wt % and the estimated Li2O reserves of 110 thousand tones. Despite the favourable infrastructure and close proximity of this stock to Ust-Kamenogorsk mining and chemical-metallurgical enterprises, its ore-generating potential has not been sufficiently studied.Materials and Methods. In this research, we obtained new data on the geological structure, age, mineral composition and formation conditions of topaz-zinnwaldite granites in the Novo-Akhmirovskoe deposit. In addition, a comparative analysis of these ores with the topaz-biotite granites of the Black Sopka massif (0.6–0.7 wt % Li2O in protolitionite) and spodumene granite porphyries of the Alakha stock (Li2O = 0.9–1.1 wt %) was conducted. Results and Discussion. It is concluded that the development of this unique nonpegmatite lithium-bearing deposit requires deep exploratory drilling, mineralogical and technological research of core samples and reconsideration of economic efficiency parameters.