Mandelstein ( German: Mandelstein ; from mandel - almonds and stein - stone) is an effusive rock with an almond -stone structure - large, somewhat elongated pores filled with various mineral neoplasms ( quartz , zeolites , chlorite , calcite ) [1] .
Content
- 1 Structure
- 2 breed formation
- 3 Deposits
- 4 notes
- 5 Links
Structure
In the Mandelstein rock, the existing gas voids and leaching voids are filled with silica minerals, carbonates , zeolites .
Breed Formation
Mandelshteins are formed when volcanic strata fall to a depth of more than several kilometers in the process of low-grade metamorphism . The processes of filling the voids contributes to the increased heat flow in volcanic areas.
In powerful trap formations (Kyuinou, Sibirskaya, Dekanskaya, Karru , Patagonskaya) and in sub-trap sequences, metamorphism is caused by the following reasons:
- Intermediate magmatic foci of vertical extent due to the expelled magma become thinner.
- There is a deflection of sections of earth platforms under the weight of many kilometers of plateau basalts and basites. Such a dive occurred under the weight of ice in Antarctica, Greenland, the Baltic Sea region.
Deposits
Mandelstein is found in the form of flows, interlayers in volcanic-sedimentary strata in river basins. Often found in beach pebbles.
Notes
- ↑ General geology: in 2 volumes / Under. ed. A.K. Sokolovsky. - M .: KDU, 2006. - T. 2. - S. 67. - ISBN 5-98227-143-8 .
Links
- Rocks (Inaccessible link) . Sochi branch of the Russian Geographical Society (July 31, 2011). Date of treatment December 7, 2015. Archived January 13, 2016.
- Spiridonov, E. M. [et al.] Geological conditions, parameters, and time for the transformation of porous basalts into almond-stone (mandelstein, including with agates) . III All-Russian Symposium on Volcanology and Paleovolcanology "Volcanism and Geodynamics". September 5-8, 2006 (Russia, Republic of Buryatia, Ulan-Ude) . Geology section of Digital Earth RAS project.