What is QSP alteration?

In these systems, phyllic alteration is commonly expressed as a quartz- 28. sericite-pyrite (QSP) assemblage that replaces original feldspars and mafic silicates (Beane, 1982), but some expressions of phyllic. 29. alteration include carbonate minerals (Sillitoe, 2010).

What is hydrothermal alteration?

Hydrothermal alteration is defined as any alteration of rocks or minerals by the reaction of hydrothermal fluid with preexisting solid phases.

What is alteration assemblages?

Alteration assemblages vary with depth and with degree of fluid interaction. In deep environments, the most highly altered areas are veins and thin selvages, or halos, that surround them. The selvages are generally <10 cm in diameter and composed of major sericite and minor quartz.

What is an alteration zone?

Alteration zones can be created around a number of the structural features (faults, shear zones, plugs, dykes and unconformities), and are defined as either alteration haloes, where the pre-existing rock property values are enhanced or depleted, or as replacement zones, where the original rock property values ar …

What causes metasomatism?

In the metamorphic environment, metasomatism is created by mass transfer from a volume of metamorphic rock at higher stress and temperature into a zone with lower stress and temperature, with metamorphic hydrothermal solutions acting as a solvent.

What is The phyllic alteration of copper?

It is commonly seen in copper porphyry ore deposits in calc-alkaline rocks. Phyllic alteration is characterised by the assemblage of quartz + sericite + pyrite, and occurs at high temperatures and moderately acidic (low pH) conditions.

What is Phyllic alteration in porphyry?

Phyllic alteration is often closely associated with argillic alteration, which occurs at lower temperatures and dominantly affects plagioclase. Phyllic alteration typically forms in the base-metal zone of a porphyry system.

What is Phyllic alteration in geology?

Phyllic alteration. Phyllic alteration is a hydrothermal alteration zone in a permeable rock that has been affected by circulation of hydrothermal fluids. It is commonly seen in copper porphyry ore deposits in calc-alkaline rocks.

What is porphyry copper?

The term “porphyry copper” is derived from the texture of the igneous rock that forms these intrusive bodies. Porphyritic texture is characterized by larger crystals of feldspar and quartz, known as phenocrysts, which are surrounded by a matrix of very fine-grained crystals.