Kudurs (mineral licks) on ultrabasic rocks in the Altai Mountains, Russia

Abstract

In the present study, the mineral and chemical compositions of kudurits consumed by wild ungulates and the chemical composition of forage vegetation near the water‑divide of the Abakan Range, Mountain Altai, Russia, were studied. It was found that the kudurits are represented by smectite‑vermiculite mineral associations with chlorite‑the products of hydrothermal transformation of metamorphosed ultrabasic rocks (serpentinites) following the intrusion of neighboring gabbroid dikes. Acid extracts (hydrogen chloride, pH 1.0) from kudurits most actively extract Ca, K, Mg, Fe and Na. In the composition of trace elements, Ba, Sr, Ni, Cu, Cr, Co, V, Zn and Li are most mobile. The comparison of the chemical composition of a kudurit and coprolite of red deer indicates that when mineral earth materials pass through the digestive tract out of all trace elements only about 0.4 g/kg of Na is reliably assimilated in the body, while kudurits simultaneously sorb and remove P, K, Mg and Ca. Chemical analyses of vegetation in places from which animals most often come to kudurs revealed high concentrations of rare earth elements. A rare‑earth‑sodium hypothesis of the cause of geophagy is developed, which may explain the majority of cases of regular consumption of earthy substances by animals and humans.