of the metasomatic biotite is observed in the Xinzhou 1000 m drill cores, and chloritization
is an essential process in which Mg-rich chlorite is produced.
of smectite, usually with corrensite as a transition phase, is a basic process of a change for 2:1 trioctahedral clay minerals (Ca and Mg smectite).
These features likely reflect hydrothermal alteration (e.g., silicification, sericitization, and chloritization
), as indicated by petrographic observation, and are not the result of magmatic fractionation.
In this depth range, the contents of [Na.sup.+], [K.sup.+], [Ca.sup.2+], and HC[O.sub.3.sup.-] significantly declined (Figure 5), which might be due to the precipitation of Cc4 as well as illitization and chloritization
Epidotization and chloritization
can be seen in fractures.
In active orogenic belt hydrothermal fluids alter feldspar and plagioclase into extremely fine grained quartz and mica in the form of muscovite or sericite by sericitization while the same fluids alter biotite and garnets into chlorite by chloritization
. Similarly the intergrowth reaction between plagioclase and k-feldspar produces fine blebs of quartz by myrmekitization which is extremely susceptible to ASR.
and Amouric, M.: 1984, Biotite chloritization
by interlayer brucitization as seen by HRTEM.
the last Hercynian phase of folding, the overthrusting of the basement by the cover rocks with lamination of the dolomite and country rock, the percolation of magnesian hydrothermal fluids and chloritization
of the aluminosilicate facies (mica schist, aplite, pegmatite), and finally metasomatic "talcification" of the dolomite and siliceous rocks.
This displacement is accompanied by hydrothermal alteration of granodiorite porphyries (chloritization
Silicification, sericitisation and chloritization
are the principal alteration types observed in the mine.