Ass 3 - How Diamonds Form

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Questions and Answers

What is a primary characteristic of diamond aggregates?

They are made up of many tiny randomly oriented diamond crystals. (correct)

They consist of large single diamond crystals.

They are porous and lightweight.

They contain various non-diamond minerals.

Where do superdeep diamonds typically form within the Earth's structure?

In volcanic regions

At the earth's surface

In the transition zone and lower mantle (correct)

In the upper mantle

Which type of volcanic eruption is primarily responsible for transporting diamonds to the earth’s surface?

Rhyolitic eruption

Basaltic eruption

Andesitic eruption

Kimberlite eruption (correct)

What is a characteristic feature of CLIPPIR diamonds?

They are large, inclusion-free, and irregular shaped. Signup and view all the answers

What is a significant factor that allows diamonds to be dated indirectly?

Inclusions of radioactive elements within some diamonds Signup and view all the answers

What is a characteristic of lamproite compared to kimberlite?

It is rich in potassium and magnesium. Signup and view all the answers

What is the primary cause of the blue color in blue diamonds?

Trace amounts of boron Signup and view all the answers

How deep do diamonds typically form in the Earth's mantle?

140 km Signup and view all the answers

Which type of diamond forms under conditions caused by a meteorite impact?

Impact diamonds Signup and view all the answers

How do the inclusions found in blue diamonds differ from those in other types of diamonds?

They consist of minerals not found in the upper mantle or transition zone. Signup and view all the answers

What happens to diamonds if the conditions under which they formed change?

They transform into a different form of carbon. Signup and view all the answers

What is the shape of the formation produced by a kimberlite eruption?

Deep carrot-shaped Signup and view all the answers

What defines the distinction of superdeep diamonds compared to crustal diamonds?

Superdeep diamonds form much deeper in the mantle. Signup and view all the answers

Where are diamond-bearing lamproites commonly found?

At the edges of cratons or immediately around them Signup and view all the answers

Which minerals are typically found in inclusions within superdeep diamonds?

Garnet and perovskite Signup and view all the answers

Which characteristic defines carbonado diamonds?

They are an aggregate form and considered the toughest. Signup and view all the answers

Which type of diamond forms deeper in the mantle than typical diamonds?

Superdeep diamonds Signup and view all the answers

What characteristic defines CLIPPIR diamonds?

They are large and inclusion-poor. Signup and view all the answers

In what kind of rocks do most diamonds form?

Peridotite and eclogite Signup and view all the answers

Under what conditions do diamonds typically form?

Temperature of 900 to 1400°C and pressure of 40 to 80 kilobars Signup and view all the answers

What process allows carbon atoms to bond and form diamonds?

Metasomatism Signup and view all the answers

Where are cratons typically found?

As the oldest parts of the earth's landmasses Signup and view all the answers

Which diamond type is characterized by its high purity and low levels of inclusions?

CLIPPIR diamonds Signup and view all the answers

What is the role of the lithosphere in diamond formation?

It provides the environment where the major igneous rock, peridotite, exist Signup and view all the answers

Very Small Crustal diamonds are typically used for ....?

Abrasives Signup and view all the answers

" Resorbed " means ....?

the surface of the diamond is partially dissolved during transport and have irregular shapes Signup and view all the answers

The subduction of oceanic plates creating CLIPPER diamonds results from what type of material?

Metallic Metal inclusions provide carbon from the exists of iron Signup and view all the answers

What type of environment do Julian Diamonds form?

formed from carbonate-rich fluids in the mantle transition zone and upper part of the lower mantle Signup and view all the answers

How do diamond atoms form differently than graphite ?

Diamond atoms are tightly connected by strong three-dimensional bonds in all directions, where graphite atoms form strong parallel bonds with weak bonds between them Signup and view all the answers

What is the main rock type associated with diamond-bearing eruptions that is more common than lamproite?

Kimberlite Signup and view all the answers

Which type of eruption typically produces a carrot-shaped formation?

Kimberlite eruption Signup and view all the answers

What geological process is responsible for delivering diamonds to the surface?

Eruption Signup and view all the answers

Where are diamond-bearing lamproites mainly found in relation to cratons?

At the edges Signup and view all the answers

Which statement is true about the metamorphic stability of diamonds?

Diamonds are stable only under specific conditions. Signup and view all the answers

What geological process primarily brings diamonds closer to the Earth's surface?

Mantle convection Signup and view all the answers

During subduction, which plate typically sinks beneath the other?

Oceanic plate Signup and view all the answers

What type of volcanic rock is typically produced by lamproite eruptions?

Potassium and magnesium-rich rock Signup and view all the answers

Which type of rock is primarily responsible for most of the diamond deposits found in the Earth?

Peridotite Signup and view all the answers

What is the typical depth where diamonds form in the Earth's mantle?

140 km Signup and view all the answers

What is the estimated temperature range necessary for natural diamond formation?

900 to 1400°C Signup and view all the answers

Which statement describes the explosive nature of lamproite eruptions compared to kimberlite eruptions?

They produce a more violent explosion than kimberlite eruptions. Signup and view all the answers

What type of geological structure is associated with the formation of superdeep diamonds?

Cratons Signup and view all the answers

What process describes the interaction of fluids or melts with rocks during diamond formation?

Metasomatism Signup and view all the answers

What is the pressure range thought to be necessary for the formation of diamonds?

40 to 80 kilobars Signup and view all the answers

Which model is thought to describe the formation of the majority of mined diamonds?

Lithospheric model Signup and view all the answers

What process is theorized to be linked to the formation of CLIPPIR diamonds?

Subduction of oceanic plates Signup and view all the answers

How does the transport of diamonds from the mantle to the surface predominantly occur?

Through volcanic eruptions of kimberlite or lamproite Signup and view all the answers

What is a major characteristic of crustal diamonds related to their formation location?

Form in the crust at or near the earth’s surface Signup and view all the answers

What type of fluid is believed to contribute to the formation of Juína diamonds?

Carbonate-rich fluids Signup and view all the answers

What is a characteristic of blue diamonds regarding their origin?

Are formed due to the subduction of hydrated oceanic plates Signup and view all the answers

Which type of diamond is most commonly linked to the impacts of meteorites?

Carbonado diamonds Signup and view all the answers

What mainly differentiates superdeep diamonds from crustal diamonds in terms of formation depth?

Superdeep diamonds form in the mantle at depths over 660 km Signup and view all the answers

What is a function of pressure in the formation of diamonds in the mantle?

Allows the formation of denser minerals Signup and view all the answers

Study Notes

Diamond Formation

Diamonds are made of carbon
Diamonds have strong 3-dimensional bonds
Graphite has strong parallel bonds with weak bonds between them
Diamonds form in the Earth's mantle
The Earth's crust is thin compared to the lower layers
The continental crust is thicker than the oceanic crust
The mantle layer is between the crust and the outer core
The lithosphere includes the crust and the uppermost part of the mantle
Plate tectonics involves the movement of 15 plates
Mantle convection drives plate movement
Diamonds form at depths of 250-300 km in the mantle

Diamond Formation Sources

Diamonds primarily form in peridotite and eclogite rocks
Peridotite is a type of igneous rock
Eclogite is a metamorphic rock formed from oceanic crust
Diamond formation needs high temperature (900-1400°C) and pressure (40-80 kilobars)
Two models for diamond formation: lithospheric and superdeep
Superdeep diamonds form in the transition zone and lower mantle (410-660 km and >660 km)
These diamonds often include unusual minerals like ringwoodite, wadsleyite, and Bridgmanite

Diamond Formation Processes

Diamonds form through metasomatism, the process of fluids or melts interacting with rocks
Fluid and melt reactions change rocks' composition as they move through the mantle
Superdeep diamonds, like CLIPPIR, blue, and Juína, often form through subducted oceanic plates
Carbon atoms must bond without oxygen at extreme pressure and heat
Metallic melt inclusions are associated with some diamonds
Trace amounts of boron can create blue diamonds
Crustal diamonds form near the Earth's surface through impacts
Large impact events can convert carbon to diamond
Diamonds are found in Kimberlite and Lamproite volcanic eruptions

Diamond Characteristics

Carbonado diamonds are an aggregate of intergrown crystals and are very tough
Diamonds are pure carbon without radioactive elements
Determining a diamond's age is difficult but can be inferred from mineral inclusions
Diamonds can be transported to the surface in kimberlite and lamproite eruptions
Kimberlite is richer in magnesium than lamproite, both lack feldspar
High temperature and pressure needed for diamond formation

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Description

This quiz explores the formation of diamonds, focusing on their carbon composition and the conditions required for their formation deep within the Earth's mantle. It also covers the differences between diamonds and graphite, and the geological processes such as plate tectonics and mantle convection that contribute to diamond formation. Test your knowledge on igneous and metamorphic rocks related to diamond sources!