Illite-Chlorite zone
Chemical Process (Alteration) - Open system under ground (Neutral metasomatism)
Correlated: Prehnite-Pumpellyite facies, Albite-Epidote-hornfels facies
Synonym
Illite zone, Chlorite zone, Propylite zone, Sericite zone
Index Minerals
Illite, Chlorite, Adularia, Albite
Required Geological Setting
Occurrence
Metasomatic zone formed by neutral hydrothermal fluid of 220-300 degree associated with Andesitic magma activities. This alteration is called Illitization, Chloritization, or Sericitization, and is a part of Propylitization. Illite-Chlorite zone may be associated with Kuroko massive sulfide deposits, Backarc-type massive sulfide deposits, Cyprus-type massive sulfide deposits, Felsic-Siliclastic type massive sulfide deposits, Moderate-T hydrothermal deposits, or Porphyry copper deposits.
Distribution of sericitization zones described in this site. Yellow lines are volcanic fronts.
Change of mineral assemblages
- [ Extinct ] Smectite/Illite, Smectite/Chlorite
- [ Appear ] Illite, Chlorite, Adularia, Prehnite, Albite
Mineral Assemblages
- [ Felsic Rocks ] Illite, Adularia, Quartz, Pyrite, Calcite, (Anhydrite)
- [ Mafic Rocks ] Chlorite, Epidote, Prehnite, Albite, Calcite, (Pumpellyite, Dolomite)
Localities
- Awashiro Mine (Sericitization)
- Harimichi Pass (Sericitization)
- Iri-Kruizawa (Thulite)
- Kami-Takeshi (Epidote, Nodule)
Related Occurrences
- Halloysite zone (Alunite zone, Argillized zone)
- Kaolinite zone (Alunite zone, Argillized zone)
- Minamiite-Alunite zone (Alunite zone)
- Pyrophyllite zone
- Smectite zone (Argillized zone)
- Interstratified mineral zone (Argillized zone)
- Illite-Chlorite zone (Propylite zone)
- Epidote-Actinolite zone
- Stilbite-Mordenite zone (Zeolite zone)
- Heulandite-Analcime zone (Zeolite zone)
- Laumontite-Albite zone (Zeolite z., Propylite z.)
- Wairakite-Albite zone (Zeolite zone)