Hydrothermal Ore Deposits

Summary

This educational video explores hydrothermal deposits, which form from hot water solutions carrying metals from magma. It explains the formation of epigenetic deposits and classifies them into hypothermal, mesothermal, and epithermal based on depth and temperature. The script also discusses two types of hydrothermal deposits: cavity filling and replacement, with examples like Fisher veins and replacement loads. It covers various deposit types, their characteristics, and the metals they contain, providing a comprehensive look at the subject.

Takeaways

• 🌋 Hydrothermal deposits are formed from hot water solutions that carry metals from magma after magmatic differentiation.
• 🔥 The term 'epigenetic' refers to deposits formed after the formation of the host rock, and hydrothermal processes are key in their formation.
• 🏺 Common metals found in hydrothermal deposits include gold, silver, copper, lead, zinc, and mercury.
• 🌡️ Hydrothermal deposits are classified based on depth and temperature of deposition into hypothermal, mesothermal, and epithermal groups.
• 🏰 Hypothermal deposits form at great depths and high temperatures (300-500°C), and may contain native gold, sulfides, and oxides.
• 🏞️ Mesothermal deposits form at intermediate depths and temperatures (200-300°C), and are typically rich in copper, zinc, silver, and gold.
• 🌅 Epithermal deposits form at shallow depths and lower temperatures (50-200°C), and are often sources of silver, gold, and mercury.
• 🔩 Hydrothermal deposits can also be classified based on formation mode into captive filling deposits and replacement deposits.
• 🏰 Cavity filling deposits occur when hydrothermal solutions deposit minerals in openings within rocks, without involving replacement.
• 🔄 Replacement deposits form through chemical interaction between hydrothermal solutions and country rock, leading to the deposition of ore minerals.
• 📊 Types of cavity filling deposits include fissure veins, stockwork, saddle reefs, ladder veins, and gossan veins, each with distinct characteristics and settings.

Q & A

What does the term 'hydrothermal' mean in the context of mineral deposits?

In the context of mineral deposits, 'hydrothermal' refers to hot water with temperatures ranging from 50 to 500°C, which carries metals originally present in magma, resulting from magmatic differentiation.

What are epigenetic deposits?

Epigenetic deposits are those that are formed after the formation of the host rock, and deposits formed by hydrothermal solutions are called hydrothermal deposits.

List the common metals found in hydrothermal deposits.

Common metals found in hydrothermal deposits include gold, silver, copper, lead, zinc, and mercury.

What are the three groups of hydrothermal deposits based on depth and temperature of deposition?

The three groups of hydrothermal deposits based on depth and temperature of deposition are hypothermal, mesothermal, and epithermal deposits.

At what temperature range do hypothermal deposits form?

Hypothermal deposits form at great depths and high temperatures, with temperatures ranging from 300 to 500°C.

What are the characteristics of mesothermal deposits?

Mesothermal deposits form at intermediate depths and temperatures, with temperatures ranging from 200 to 300°C.

What is the temperature range for the formation of epithermal deposits?

Epithermal deposits form at shallow depths and relatively low temperatures, with temperatures ranging from 50 to 200°C.

What are the two classifications of hydrothermal deposits based on the mode of formation?

Hydrothermal deposits are classified into two groups based on the mode of formation: cavity filling deposits and replacement deposits.

How do cavity filling deposits form?

Cavity filling deposits form when hydrothermal solutions deposit their dissolved minerals in various types of openings present in the rock, without involving replacement.

What are some common types of cavity filling deposits?

Common types of cavity filling deposits include fissure veins, share zone deposits, stock work, saddle reefs, ladder veins, and gossan veins.

How do replacement deposits differ from cavity filling deposits?

Replacement deposits form due to chemical interaction between the hydrothermal solution and the country rock, where the original minerals are dissolved and replaced by ore minerals.

What are the three types of replacement deposits?

The three types of replacement deposits are massive deposits, replacement load, and disseminated deposits.