Geology

Zavarotnaja Bay

In the night of July, 28th, we reached this little harbour with our boats.

[The harbour at the Zavraotnaja Bay]

The harbour was built for the transport of propylite, a rock that was mined 10 km from there in the mountains west of the lake. The deposit of this rock was discovered in the 1960´s and had some importance for the former USSR, because it was the only significant source for high quality propylite in the whole country. This rock is a hydrothermal altered volcanic tuff with 65 to 70% SiO₂ content. Its mineralogical composition is 20% quartz, epidote, chlorite and prehnite. It is a compact, very hard rock of a green colour.

[Propylite]

The mine was operated until the end of the 1980´s by open pit and underground mining. The propylite was used for the surface finishing of special steels, especially military ones.
The mountains behind the harbour belong to the Baikalsky Range, in which also the famous Lena River has its springs. Between the Zavarotnaja Bay and the camp of the Baikalsky reservation, where we stopped next, the geology is dominated by large granitic intrusion. In the hanging wall of the inrusion a volcanic series crops out with a volcanic slot from the intrusion. These volcanic series are the reason for the occurrence of the propylite and zones of enrichment of different metals like gold, copper, REE and some others. But these metal occurrences are just small with low ore grades, so they have no economic importance.

top