Gold in Yurassic deposits of the Vilyuj synesclise; Zoloto v yurskikh otlozheniyakh Vilyujskoj sineklizy

A hypothesis explaining the origin of the Vilyuj gold-bearing province (South-Yakut) is studied. The formation of gold deposits is shown to result from the gold bedrock destruction in the Yurassic depositions. The karst origin of gold in connection with the Yurassic fluid-gas volcanicity is grounded both hydrothermally and metasomatically. The table data on strontium composition and on rubidium and strontium concentration in pebbles and rock waste of alkali (potash feldspar) trachytes and tuffs of alkali trachytes from `blended` bundle of the lower Yura selected in the middle flow of Amga river are presented here. The radiological age of alkali trachytes and their tuffs constitutes 203-218 mln. years. 20 refs.3 figs., 1 tab.