Genetic Processes of Ore Formation Overview

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What is the key process involved in the migration of hydrothermal fluids in ore formation?

Percolation through any type of rock

Fluid flow along interconnected cracks and fractures (correct)

Sudden expulsion from the volcanic system

Random dispersion throughout the rock matrix

In hydrothermal systems, the geometry of ore bodies is primarily dependent on:

The type of hydraulic equipment used in the process

The geometry of the fluid conduits (correct)

The size of the mineral grains within the ore

The color of the surrounding rocks

What type of structures are preferred for fluid focussing in ore formation?

Flat, horizontal layers of rocks

Mountainous terrain

Shear zones, faults, breccias, and stockworks (correct)

Rounded boulders

What factor plays a significant role in concentrating dissolved constituents into a portion of the Earth's crust for ore formation?

Rock strength and structural conduits Signup and view all the answers

Which type of flow helps define the geometry of the orebody in hydrothermal systems?

Focused flow through restricted channel ways Signup and view all the answers

What characteristic defines the migration of fluid along shear zones to provide geometric focusing and enhanced fluid interaction?

Kilometre-scale migration Signup and view all the answers

What is the driving mechanism for fluid migration in hydrothermal systems?

Temperature gradient (convection) Signup and view all the answers

How does fluid convection around a magmatic intrusion occur?

Driven by heat anomaly Signup and view all the answers

What controls the precipitation of metals from hydrothermal fluids?

Reduction in solubility of the metal-ligand complex Signup and view all the answers

What is the primary mechanism for extracting metals from hydrothermal fluids?

Destabilizing the metal-ligand complex Signup and view all the answers

Which factor contributes to fluid migration in hydrothermal systems due to rock deformation?

Tectonic stress Signup and view all the answers

What causes the metal to be deposited in the host rock in hydrothermal systems?

Destabilization of the metal-ligand complex Signup and view all the answers

What results in the loss of volatiles like CH4 and CO2 in hydrothermal systems?

Boiling and effervescence Signup and view all the answers

Which reduction mechanism causes reduced volatile species to partition more readily into the vapor phase?

2H2O + CO2 = 2O2 + CH4 Signup and view all the answers

What does an increase in the pH of the residual fluid indicate in hydrothermal systems?

Loss of volatiles Signup and view all the answers

How do rapid pressure releases occur in hydrothermal systems?

Hydraulic fracturing Signup and view all the answers

What leads to an increase in the oxygen fugacity (fO2) of the fluid in hydrothermal systems?

Oxidation of the fluid Signup and view all the answers

What increases the ratio of SO4 to H2S (SO4²⁻/HS⁻ ratio) in the residual ore fluid?