PETROLOGY AND ORE MINERALIZATION OF ULTRABASITES OF THE TERNOVKA MASSIF OF THE DEVLADOVO REGIONAL FAULT ZONE

Velikanova O.Y., Velikanov Y.F.

M.P. Semenenko Institute of geochemistry, mineralogy and ore formation of NAS of Ukraine, Kyiv, Ukraine, olgavelikanova1@rambler.ru

 

The Ternovka massif is located in the south-eastern flank of the Ternovka syncline, strikes submeridionally 5 km at thickness from 300 to 400 m.

The massif consists of peridotites and dunites emplaced in medium-crystalline metabasic host rocks. Peripheral parts of the massif contain actinolite-tremolite, talc-chlorite and talc-calcareous rocks. Locally, the ultrabasites are serpentinitized, carbonatized, talcitized, amphibolitized or chloritized.

The Ternovka ultrabasites are subalkaline (K_A = 0.4 %) high magnesim rocks (K_M = 89.5 % at F/M =  6.3 %). Major prospective ore elements in the ultrabasites are Ni, Co, Cu, Cr, Au and Pt.

Average Ni content in peridotites and serpentinites – 0.23 %. In residual soil, Ni concentration reaches 2 %. Average content of Co in peridotites and serpentinites is around 0,02 %. Ni and Co are preferentially concentrated as impurities in magnesium-ferrous silicates. In additional, Ni is accumulated in millerite and pentlandite but also was detected in actinolite (0.1 %), magnetite (0.14 %), pyrrhotite (0.6 %) and talk (0.4 %).

Cu is mostly accumulated in chalcopyrite although minor Cu was also detected in pyrite and pyrrhotite.

Cr concentration varies from 0.2 to 0.69 %. Chromite is a single Cr-mineral in the rocks.  In additional, Cr dopes olivine (0.25 %), actinolite (0.26 %), chrysolite (0.21 %), chlorite (0.28 %) and magnetite (0.60 %).

Au content in the ultrabasites reaches 0.015 ppm in the zones of superimposed sulfide mineralization, quartzification and carbonatization. Anomalous Au contents up to 0.3 ppm were found in a late quartz veinlet.

Of PME, the ultrabasites contain up to 0.014 ppm of Pd. Ir and Rh were detected as traces.