Topic 10 Flashcards
Hematitization is commonly associated with which type of alteration in rocks?
A. Silica replacement
B. Iron oxidation leading to a reddish hue
C. Carbonate deposition forming white streaks
D. Sulfide mineralization creating metallic luster
B. Iron oxidation leading to a reddish hue
What is the primary result of greisenization in granite?
A. Formation of a greenish hue due to the presence of chlorite
B. Alteration of feldspar to form quartz and mica (muscovite)
C. Conversion of granite into basalt
D. Introduction of sulfide minerals
B. Alteration of feldspar to form quartz and mica (muscovite)
Which of the following geological processes can lead to silicification?
A. Hydrothermal activity
B. Volcanic eruptions
C. Groundwater action
D. All of the above
D. All of the above
When a veinlet cuts across a vein in veinlet chronology, what does this indicate?
A. The veins formed before the veinlets
B. The veins formed after the veinlets
C. The veins and veinlets formed simultaneously
D. The veins are unrelated to veinlets
A. The veins formed before the veinlets
Alteration of an igneous rock during the final crystallization stages (very high-T) of the molten rock, but some changes can be delayed after solidification.
A. Deuteric Alteration
B. Retrograde Alteration
C. Prograde Alteration
D. Hydrothermal Alteration
A. Deuteric Alteration
Secondary Biotite forms at high temperature replacement (240-500°C) of plagioclase and Fe-mags due to hydrothermal and regional metamorphic process.
A. True
B. False
B. False
Chemical formula of Magnetite (Secondary).
A. Fe3O4
B. Fe4O3
C. Fe3O5
D. Fe4O4
A. Fe3O4
A sulphate mineral that is common in VMS and mixing zones of high-sulfidation epithermal deposits.
A. Gypsum
B. Anhydrite
C. Barite
D. Alunite
C. Barite
Anhydrite occurs in neutral and acidic zones (pH 6-2). It is abundant in ____________, especially where acid and neutral mix. It is also indicative of boiling.
A. Alteration zones
B. Boiling zones
C. Cooling zones
D. Permeable zones
D. Permeable zones
- (Fe₂O₃) a mineral that is common in oxidized (hypogene) skarn deposit.
A. Specularite
B. Magnetite
C. Calcite
D. Magnesite
A. Specularite
Is a ubiquitous iron sulfide alteration mineral occurring in most hydrothermal deposits.
A. Calcite
B. Epidote
C. Albite
D. Pyrite
D. Pyrite
Characterized by the destruction of primary minerals, such as feldspar and mica, and the formation of clay minerals.
A. Advanced Argillic
B. Propylitic
C. Potassic
D. Skarn
A. Advanced Argillic
Form as a result of alteration that occurs when hydrothermal fluids interact with a protolith of either igneous or sedimentary origin.
A. Argillic
B. Propylitic
C. Potassic
D. Skarn
D. Skarn
Vuggy silica is characterized by small cavities developed in a rock resulting in a spongy appearance, caused by extreme ______________ of all minerals and major elements.
A. heating
B. acidic leaching
C. oxidation
D. NOTC
B. acidic leaching
Alunite is an analog of __________ and, a very low-T supergene, where aluminum replaces Fe³⁺.
A. Gold
B. Cassiterite
C. Wolframite
D. Jarosite
D. Jarosite
Hydrothermal alteration zone that occurs under low temperatures and higher pH, with minerals like chlorite, epidote, and carbonates
Propylitic
Which hydrothermal alteration zone is characterized by high temperatures, potassium enrichment, and minerals such as orthoclase, sanidine, and microcline?
Potassic
Characterized by the alteration of primary minerals to secondary minerals such as muscovite, kaolinite, and sericite
Phyllic
Which sulfide mineral is a common indicator of gold deposition during the retrograde stage of hydrothermal processes?
Pyrite
This is part of your oxy-salts group specifically as Tungstates that has the chemical formula of CaWO4
Scheelite
Sodium can substitute for potassium in alunite, and when the Na content is high, it is called ____________
Natroalunite
Greisenization happens when fluids rich in fluorine, boron, or other volatiles interact with the granite, altering its original minerals like feldspar and turning them into _____________.
Greisen
____________ is a late-stage clay mineral, it overprints hypogene alteration or as supergene mineral in nearly all hydrothermal deposits.
Kaolinite
It is the alteration type occurrence of opal.
Advanced argillic
These are minerals at or near-surface.
Supergene Minerals
Primary hydrothermal/unaltered minerals
Hypogene Minerals
It is a process or alteration associated with oxidizing fluids, forming high Fe3+ / Fe2+ ratio
Hematitization
Retrograde alteration of epidote: ___________ and ___________.
Chlorite and Calcite
Conversion of a carbonate mineral or rock into a silicate mineral or rock; common in prograde stage of skarn and porphyry deposits.
Silication
