Geological structure and material composition of rocks and ores of the Kalyumnoe site.
Subsurface site “Kalumnoe” – Current data
The stratified series of the Synnyr massif in the area of the licensed block consists of rhythmic layering of alkaline gabbroids, as well as melanocratic syenites (at the base) associated with them, and leucocratic feldspathoid (nepheline, nepheline-calsilite or calsilite) syenites in the upper part. The rocks of the stratified series (in the study area and beyond in the northeastern part of the Synnyr massif) have a low-angle bedding of both feldspathoid syenites and alkaline gabbroids. The full dip of the rocks do not exceed 10-15 degrees (west, northwest), and only in the center of the subsurface site Kalumnoe a northwest dip with angles up to 30-35 degrees is observed.
The formation of the intrusive complex took place in the conjunction zone of two regional diagonal fault structures of the north-eastern and north-western strike. The formation of these structures began in the Proterozoic; along them there are still tectonic activities. As a result, there is a dense network of multidirectional disturbances, which are accompanied by crushing zones, slickensides, metasomatic occurrences of a different nature and scale. A fault set forms a series of small blocks on the study area, and the eastern part and the central part of the productive zone, where the rocks of the stratified series have maximum angles of incidence to the northwest, are characterized by maximum fragmentation. On the eastern flank, the fall of the rocks becomes more gentle, tends to zero, and the size of the blocks is noticeably enlarged.
The central part of the Synnyr alkaline massif is built of feldspathoid (calsilite, nepheline-calsilite and nepheline) syenites, alkaline gabbroids (shonkinites) and associated alkaline syenites with varying degrees of melanocracy, alkaline and nepheline containing syenites, lamprophyre dykes, veined alkaline and nepheline syenites, and extremely rare alkaline granites. Intensive processes of metasomatism led to the appearance of microcline, microcline-zeolite, microcline-sericite, sodalite-cancrinite, albite and albite-scapolite metasomatites.
Calsilite syenites (synnyrite): currently depending on structural and textural features they are divided into pseudoleucitic with the presence of a variety of symplectic aggregates of potassium feldspar and feldspathoids (from thin dactylotypic to micrographic) and granular varieties. In the geological section of the deposit stratified series, rocks composed of symplectic aggregates occupy the upper parts, while granular ones form the basis of deeper horizons. At the same time, pseudoleucitic rocks contain minimal amounts of dark-colored and accessory minerals, while the role of biotite and clinopyroxene significantly increases in granular ones and the concentration of apatite sharply increases.