MICROTOPOCHEMISTRY AND GEOCHEMICAL FEATURES OF A PYRITE NODULE OF СARBONACEOUS SILTSTONES OF THE SAF′YANOVKA MASSIVE SULFIDE DEPOSIT (CENTRAL URAL)

Abstract

Pyrite nodules of carbonaceous siltstones of the Saf´yanovka nonmetamorphosed massive sulfide deposit consist of a porous poikilitic pyrite core (zone A), which is partly transformed to metacrystalline pyrite aggregates at the periphery (zones В и С). According to LA-ICP-MS data, elements both of ore (Cu, Zn, Pb, In, Cd, Sn, Fe, S, Co, Ni, Se, Au, Sb and Bi) and hyaloclastic (Si, K, Al, Mg, Ga, V) associations are concentrated in the core centre (zone A). The elements of ore association are also dominant in the zone B. The zone С is depleted in trace elements except for As (up to 0.7 wt. %). Comparing with pyrite nodules from sulfide turbidites, this nodule exhibits much higher contents of Au (up to 35.3 ppm) and Ni (up to 614 ppm). It is supposed that organic material is a further additional source of Au and Ni in pyrite nodules hosted in black shales. In contrast to pyrite nodules from the Bracemac-McLeod (Canada) and Lahanos (Pontides) massive sulfide deposits (Genna, Caboury, 2015; Maslennikov et al., 2017), the outer zone of the Saf’yanovka pyrite nodule is depleted in most trace elements indicating incomplete geochemical cycle of autigenic mineral formation.

Keywords

• saf´yanovka deposit
• carbonaceous siltstones
• diagenesis
• pyrite nodule
• trace elements