What is Paragenetic sequence?
paragenesis, the sequence in which the minerals are formed in an ore deposit. Variations in the pressure and temperature and in the chemical constituents of a hydrothermal solution will result in the precipitation of various minerals at different times within the same ore deposit.
What is the meaning of Paragenetic?
: the formation of minerals in contact in such a manner as to affect one another’s development.
What is metamorphic paragenesis?
Paragenesis is a petrologic concept meaning an equilibrium sequence of mineral phases. It is used in studies of igneous and metamorphic rock genesis and importantly in studies of the hydrothermal deposition of ore minerals and the rock alteration (vein metasomatism) associated with ore mineral deposits.
What is wall rock alteration?
wall-rock alteration A reaction of hydrothermal fluids with enclosing rocks, causing changes in mineralogy that are most marked adjacent to the vein and become less distinct further away. See HYDROTHERMAL ACTIVITY; and HYDROTHERMAL MINERAL.
What is mineral zoning?
The term ‘mineral zoning’ refers to the systematic spatial variation in the composition of a single mineral grain. Concentric zonation reflects compositional variations perpendicular to the crystal surfaces, whereas sector From: mineral zoning in The Oxford Companion to the Earth »
What is AKF diagram?
[¦ā¦kā¦ef ′dī·ə‚gram] (petrology) A triangular diagram showing the chemical character of a metamorphic rock in which the three components plotted are A = Al2O3+ Fe2O3+ (CaO + Na2O), K = K2O, and F = FeO + MgO + MnO.
How do zeolite facies form?
Minerals in this series include zeolites, albite, and quartz. This occurs by dehydration of the clays during compaction, and heating due to blanketing of the sediments by continued deposition of sediments above.
What are the types of alteration?
Types of alterations
- Potassic alteration.
- Phyllic (sericitic) alteration.
- Propylitic alteration.
- Argillic alteration.
- Silicification.
- Carbonatization.
- Greisenization.
- Hematitization.
What is ore bearing fluid?
Minerals are formed by changes in chemical energy in systems which contain one fluid or vapor phase. In nature, minerals are formed by crystallisation or precipitation from concentrated solutions. These solutions are called as ore-bearing fluids.
Which mineral shows zoning?
Normal or continuous zoning: zoning in which the outer portions of the crystal have a lower-temperature composition than the core. Usually reflects progressive change of melt composition during growth of the crystal. Plagioclases are normally zoned from calcic cores to more sodic rims.
What causes mineral zoning?
Zoning results from the mineral’s inability to maintain chemical equilibrium with a magma during rapid cooling; the zonation represents a frozen picture of the continuous reaction series for that mineral.
What is Chemographic diagram?
Minerals and rocks have chemical compositions that comprise some of the most important data for phase equilibria studies. Important relationships among rocks and minerals can be discovered or demonstrated by the construction of composition diagrams (also called chemographic diagrams) to display the data.
What rocks are in the zeolite facies?
This facies also called “zeolite facies” contains mica, smectite-group-minerals, kaolinite-group minerals, chlorite s.s.s. quartz and hematite in metapelitic rocks. Zeolites which this metamorphic facies takes its name from are only present in metabasic and quartz-feldspar rocks.
What is a zeolite mineral?
zeolite, any member of a family of hydrated aluminosilicate minerals that contain alkali and alkaline-earth metals. The zeolites are noted for their lability toward ion-exchange and reversible dehydration.
How are minerals altered?
Alteration minerals are typically formed by mineral replacement, direct deposition, (filling in vesicles, vugs or fractures) or leaching (dissolution without replacement).
What is alterations in geology?
[… in rocks] Any change in the mineralogic composition of a rock brought about by physical or chemical means, esp. by the action of hydrothermal solutions; also, a secondary, i.e., supergene, change in a rock or mineral.