Abstract
The paper presents mineralogical, crystallochemical, and Rb–Sr age data on globular layer silicates of the glauconitic series from lower horizons of the Upper Riphean Kil'din Group, Srednii Peninsula. Chloritization significantly changed the globular Al-glauconite in sandstones of the Parajarvinskaya Formation. However, it almost did not affect glauconite globules in sandstones of the Palvinskaya Formation and altered only clayey component of the rock. Mossbauer spectroscopy showed that Al-glauconite in the Palvinskaya Formation was affected by secondary transformations, which caused the Fe2+ oxidation in octahedral sheets and loss of radiogenic 87Sr. The transformations were presumably related to exhumation of rocks of the Parajarvinskaya and Palvinskaya formations to the circulation level of the oxygen-rich meteoric waters. Thus, Rb–Sr datings obtained for Al-glauconites of the Palvinskaya (781–786 Ma) and Parajarvinskaya(744–751 Ma) formations correspond to the tectonic uplift of Kil'din rocks and have no stratigraphic significance.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
