Age paradoxes of Devonian magmatism of the northeastern part of the Kola Peninsula |
| |
Authors: | E N Terekhov A S Baluev T F Shcherbakova I S Ipat’eva |
| |
Institution: | 1.Geological Institute,Russian Academy of Sciences,Moscow,Russia |
| |
Abstract: | A structural-geochemical study has been conducted on the dikes of presumably Devonian mafic rocks confined to a small graben
filled in with Riphean sedimentary rocks hosted by Early Precambrian granite-gneiss of the Murmansk block. It has been demonstrated
that the dolerite dikes of this region can be considered as manifestations of trap magmatism whose products fill in the foundation
of the East Barents riftogenic downfold. In turn, manifestations of alkaline and kimberlite rocks of the White Sea region
are confined to the peripheral portion of the trap magnetism area. Zircons from dolerite transecting Late Riphean sediments
examined in two laboratories have a concordant age of 2.74–2.72 Ba, while zircons from a similar dike located in granite-gneiss
of the basement are characterized by an age range of 2700–155 Ma, and the concordant age based on 4 points is 790 Ma. All
these factors indicate that the age determinations of the mafic rocks are ambiguous, particularly in the zone of transition
from the center of the trap province to its periphery, where alkaline magmatism is observed. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|