Exploring the Link Between Seismic Activity and Gold Nugget Formation in Quartz Veins

Exploring the Link Between Seismic Activity and Gold Nugget Formation in Quartz Veins

Sub: Geo

Sec: Physiography

Why in News

Recent research published in Nature Geoscience on September 2 has proposed a novel explanation for why gold nuggets are frequently found in orogenic quartz veins in mountainous regions. This study offers insights into the role of seismic activity and the piezoelectric properties of quartz in the formation of these gold deposits, a phenomenon that has puzzled scientists for years.

Explained:

Researchers have discovered that the formation of gold nuggets in orogenic quartz veins may be driven by seismic activity. Experiments confirmed that seismic waves from earthquakes can cause these reactions, gradually accumulating gold over time. This study provides a new explanation for the localization of gold nuggets in quartz veins, emphasizing the role of seismic activity and basic scientific principles in natural gold formation.

Gold Nuggets: Gold nuggets are naturally occurring lumps of gold, usually composed of high-purity gold (around 85-95%).They can contain small amounts of silver and other trace metals.

Gold nuggets vary widely in size, from tiny particles visible only under a microscope to large pieces weighing several kilograms.

The largest recorded gold nugget, the “Welcome Stranger,” weighed approximately 72 kilograms.

Gold nuggets are primarily found in alluvial deposits, which are the result of erosion and weathering of gold-bearing rocks.

Orogenic gold systems, contributing to up to 75% of the gold mined globally.

Formed through the process of piezo catalysis in quartz veins, where mechanical stress and seismic activity cause gold to deposit on the quartz.

The primary geological environment for gold nugget formation is orogenic gold systems, which are formed by the collision of tectonic plates.

Major gold nugget discoveries have been made in regions such as the Witwatersrand Basin in South Africa, the Goldfields of Australia, and the Yukon Territory in Canada. India has mined gold in regions like Kolar Gold Fields.

Quartz:

Quartz is a hard, crystalline mineral composed of silicon dioxide (SiO₂).

It is the second most abundant mineral in Earth’s continental crust, after feldspar.

Quartz is known for its hardness (7 on the Mohs scale) and resistance to weathering, making it a durable and long-lasting mineral.

It typically forms hexagonal crystals and is often transparent or translucent, with a glassy lustre.

Quartz comes in many varieties, including clear quartz (rock crystal), amethyst (purple), citrine (yellow), rose quartz (pink), and smoky quartz (brown to black).

It is commonly found in veins, pegmatites, and hydrothermal deposits, often associated with other minerals like gold, feldspar, and mica.

Quartz is piezoelectric, meaning it generates an electric charge when subjected to mechanical stress. This property is utilized in various technological applications, such as in quartz watches, pressure gauges, and electronic devices.

High-purity quartz is used in the production of silicon chips, which are essential components of electronic devices.

Major sources of quartz include Brazil, the United States (particularly Arkansas), Madagascar, and India. In India, quartz deposits are found in states like Rajasthan, Andhra Pradesh, and Tamil Nadu.

Seismic Waves:

Seismic waves are energy waves generated by the sudden release of energy in the Earth’s crust, typically due to earthquakes or volcanic activity.

They are classified into two main types: Body Waves and Surface Waves.

Body Waves: Travel through the Earth’s interior and include Primary (P) waves and Secondary (S) waves.

Surface Waves: Travel along the Earth’s surface and include Love waves and Rayleigh waves.

Primary (P) Waves: P-waves are the fastest seismic waves and the first to be detected by seismographs. They are compressional waves, moving in the direction of wave propagation, causing particles to move back and forth.

P-waves can travel through solids, liquids, and gases.

Secondary (S) Waves: S-waves are slower than P-waves and arrive after them. They are shear waves, moving perpendicular to the direction of wave propagation, causing particles to move up and down or side to side.

S-waves can only travel through solids, not through liquids or gases.

Surface Waves: Surface waves travel slower than body waves but are responsible for most of the shaking felt during an earthquake.

• Love Waves: Move the ground side to side in a horizontal plane.
• Rayleigh Waves: Cause a rolling motion, moving the ground up and down and side to side, similar to ocean waves.

Earthquake Measurement:

• The Richter scale measures the magnitude of an earthquake based on the amplitude of seismic waves.
• The Moment Magnitude Scale (Mw)is more commonly used today as it provides a more accurate measure of an earthquake’s size, considering the area of the fault that slipped and the amount of slip.

Seismic Waves and Mineral Formation:

• Seismic waves can trigger piezoelectric effects in certain minerals like quartz, leading to chemical reactions that may result in the deposition of minerals, such as gold, in quartz veins.

This study offers a compelling explanation for the formation of gold nuggets in quartz veins, attributing it to the piezoelectric properties of quartz and the mechanical stress induced by seismic activity. These findings not only solve a long-standing geological mystery but also underline the importance of basic scientific principles in understanding natural phenomena.