Hypergenic transformation of titanite
Matrenichev V. Α., Skublov S. G.
Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2015. V. 144. N 6. P. 19-34
Full text is available
Language: Russian
Abstract
Transformations of titanite in the weathering crust were studied for this mineral from Archean granitoids of North Karelia. Structural, textural and mineralogical features of ancient, pre-metamorphic weathering are widespread in these rocks. Transformations correspond mostly to physical disintegration of substrate with patches of sandy eluvium. The initial stage of weathering is represented in titanite by formation of the porous «spotty» structure with segregations of iron and titanium oxides. These sites are characterized by significant decrease in concentration of iron, with considerably increasing content of aluminum. Contents of Y, Nb, Hf, Th become lower in 1.5—2 times, and REE lesser in 3 times. Progress in hypergenic transformation leads to the complete destruction of titanite with its replacement by aggregate of quartz, calcite, anatase and rare-earth fluorine-carbonates.
Key words: titanite, weathering crust, hypergenesis, Precambrian, geochemistry of minerals, REE.
