Chloritization


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chloritization

[‚klȯr·əd·ə′za·shən]
(chemistry)
The introduction of, production of, replacement by, or conversion into chlorite.

Chloritization

 

a metasomatic process in which the dark minerals of rocks and sometimes also the matrix itself are replaced by chlorites. Different types of chloritization are distinguished: regional postmagmatic chloritization of basic effusive rocks and their tuffs (seeGREENSTONE); chloritization of basic lavas associated with albitization (seeSPILITE) and of the dark minerals of acidic and intermediate igneous rocks (for example, the biotite and hornblende in granitoids); and hydrothermal chloritization of various rocks as a commonly occurring type of alteration near ores (seePROPYLITIZATION). The development of linear zones of chloritization indicates the presence of hydrothermal ore deposits.

References in periodicals archive ?
Biotite (41%) forms leafy aggregates consisting of heteroblastic and subidioblastic individuals with pleochroism from brown to pale green, and moderate chloritization.
The expected gold mineralization will be associated with breccia zones where the fault rock has been intensely sheared, altered and replaced with intense hematite and magnetite, chloritization, silicification and copper oxides related to the fault.
The alteration assemblage includes beresitization, potash feldspathization, chloritization, and carbonatization, occurring as bands in the ore-bearing faults and pervasive alteration of nearby wall rocks.
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.
In examined amphibolites is this stage characterised by occurrence of carbonate veinlets and chloritization of amphibole.
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.
On the other hand, upper limit of the time interval for emplacement of investigated dykes is defined by the origin of uranium hydrothermal mineralization, which caused chloritization and albitization of granodiorite porphyries.
Silicification, sericitisation and chloritization are the principal alteration types observed in the mine.
Albitization of the original plagioclase, chloritization of biotite and enrichment in hematite are common.
The Big Bug / Old Miner horizon is now thought, because of its intense chloritization, to be a vent feeder zone, so that the most likely place for a major deposit would be up-sequence and to the west, which would be in the Main Copper Mountain Claim Block.
Hydrothermal alteration zones, quartz-pegmatite veins and veinlets and dykes of sub-volcanic origins with intensive silicification, pyritization, and chloritization occur around the granodiorite stock body.