BASITE INTRUSIONS IN THE LATE PRECAMBRIAN HISTORY OF OMOLON MASSIF (GEOLOGIC AND GEOCHRONOMETRIC DATA)

Abstract

The results of K-Ar and Rb-Sr isochronous dating of the Late Precambrian basite intrusive rocks of Omolon Massif serve as a basis for the author to make generalized conclusions. According to the geologic interpretation of a histogram of 37 K-Ar age determinations, Strelkinsky gabbro-diabase complex formed not later than 890 mln years ago and signified the maiden episode of magmatism in the Riphean-Phanerozoic history of Omolon Massif. The results of Rb-Sr isochronous dating do not allow researchers to make an unambiguous interpretation of them. Both the Early Riphean age of Strelkinsky Complex (about 1500 Ma) can be suspected, as well as repeated manifestations of basite intrusive magmatism, which occurred during the time interval since the terminating formation of crystalline foundation through the starting formation of the sedimentary cover of Omolon Massif. According to Rb-Sr age determinations, Fe and Au minerals are related to the active foundation processes through the Riphean. In consideration of Rb-Sr dates, the genetic relationships between Fe ores and Au mineralization, and the Riphean active stage of the Omolon Massif foundation are discussed in this paper.