Altered rock type is strongly associated with intense silicification, pyritization, chloritization
and illitization and its protolith are commonly volcanic breccia and tuff (Fig.
Volcanic host rocks have hydrothermally been altered and can be divided into four parts vertically: kaolinization, chloritization
, epidotization, and silicification.
Pyroxene crystals are altered, affected by chloritization
The inferred paragenetic sequence of the studied sandstone include both physical and chemical compaction, dissolution of feldspars and kaolinitization, chloritization
and illitization ofsmectite, quartz overgrowth, calcite cementation and dolomitization, uplifting and deformational bands formation, and iron oxide/hydroxide cementation and its partial dissolution.
of Late Ordovician K-bentonites from the northern Baltic Palaeobasin - influence from source material or diagenetic environment?
In the depocentre of the basin, a low-grade metamorphic event (hydrothermalism) took place, leading to some mineralogical changes in the original petrofacies, including silicification, chloritization
and the albitization of feldspars.
The appearance of a similar phenomenon as an evident relict in the Dividal Group rocks of Lapland is remarkable, because during the local post-diagenetic deep changes (sericitization and chloritization
of sedimentary rocks), the reduction, which is probably caused not by organic matter, but by other reductive fluids, encompasses the entire rock massive.
Clearly, hydrothermal breccias, related pervasive alteration and mineralization (silicification, chloritization
, and greisenization) in GRI and GRII (Kooiman et al.
The Lasenice granite was described as an independent early-stage intrusion in the Moldanubian batholith, because it shows an intensive tectonic deformation, partly connected with a chloritization
(Klecka and Rajlich 1984).
Laterally extensive sericitization and chloritization
affect the Contact Unit's basal footwall breccia.