Part 1- Intro

Question 0

What do ppm and ppb mean in terms of trace elements?

Answer 0

• Ppm = 1 micro g in 1g of rock

* Ppb = 1ng in 1g of rock

Question 1

What are trace element abundances usually quoted in?

Answer 1

Ppm or ppb

Question 2

What do major elements govern in rocks?

Answer 2

The mineralogy

Question 3

What do trace elements do in a rock?

Answer 3

Substitute into mineral phases

Question 4

What is a lithophile element?

Answer 4

• “rock-loving”

* partition into silicate phases

Question 5

What is a siderophile element?

Answer 5

• “metal-loving”

* Partition into metallic liquids

Question 6

What is a chalcophile element?

Answer 6

• “Sulphur-loving”

* Partition into sulphide liquids

Question 7

What is an atmosphile elements?

Answer 7

• Highly-volatile

* Form gases or liquids at Earth’s surface

Question 8

Which two groups of elements bond together with which type of bonding to form oxide silicate minerals?
Therefore what classification do they belong to?

Answer 8

• Low and high electronegativity elements forming iconic bonds
• lithophile

Question 9

What electronegativities do siderophile and chalcophile elements have? What bonding do they prefer?

Answer 9

• Intermediate

* Covalent and metallic

Question 10

What type of sulphide liquids does the term chalcophile include?

Answer 10

Magmatic NOT AQUEOUS

Question 11

What does HSE stand for?

Answer 11

Highly Siderophile Elements

Question 12

Give an example of an element that exhibits more than one type of Goldschmidt’s behaviour…

Answer 12

Nickel- is siderophile therefore concentrates in the core.

Behaves as lithophile in the mantle and substitutes for Mg in olivine

Question 13

How does ionic radius vary across a period?

Answer 13

Decreases

Question 14

How does ionic radius vary down a group?

Answer 14

Increases

Question 15

How much can the ionic radii of ions vary for them to be able to substitute?

Answer 15

Up to 15%

Question 16

How much can an ions charge vary by before it isn’t substituted?

Answer 16

One unit

Question 17

Are elements with a higher or lower ionic potential preferred for substitution?

Answer 17

Higher because they form stronger bonds

Question 18

When size and charge of the substituting ions are similar what else can stop substitution occurring? (2)

Answer 18

• Different electronegativities

* Form bonds of different ionic character

Question 19

What is the camouflage principle?

Give an example.

Answer 19

When two ions have virtually the same charge, ionic radii and electronegativity.

E.g.
Zr and Hf in Zircon

Question 20

What is the capture principle?

Answer 20

When a trace is used in a mineral over a major because the trace has a higher ionic potential

Question 21

What is the admission principle?

Answer 21

When ions are incorporated that have a lower ionic potential than the major

Question 22

What essential does a partition/distribution (KD) coefficient mean?

Answer 22

How well a trace element partitions in a mineral from a melt

Question 23

What KD value do compatible elements have?

Do they prefer solid or melt

Answer 23

KD > 1

Prefer solid phase

Question 24

What KD value do incompatible elements have?

What phase do they prefer?

Answer 24

KD < 1

Prefer Liquid

Question 25

What is the bulk partition coefficient (D)?

Answer 25

The sum of the individual partition coefficients weighed according to the relative proportions (mass fraction) of the mineral phases present

Question 26

How can elements be deemed compatible in the mantle?

Answer 26

If they can substitute for the major cations that exist there

Question 27

What does PGE stand for?

Are they compatible in the mantle?

Answer 27

Platinum Group Elements

Yes- partition strongly into mantle sulphides

Question 28

What elements do the HSE include?

Answer 28

PGE and Re

Question 29

Give an example of 2 elements that are incompatible in the mantle and thus where are they enriched?
Which of the 2 is more incompatible.

Answer 29

Rubidium (Rb) and Strontium (Sr)
Enriched in melt phases.
Rb is more incompatible.

Question 30

What does LILE stand for

Answer 30

Large Ion Lithophile Elements

E.g. Rb, Sr, Cs, Ba

Question 31

What is the only type of mineral in which Sr is compatible?

Where are the most dramatic Rb/Sr fractionations due to this?

Answer 31

• Feldspars

* Continental crust

Question 32

What does REE stand for?

Answer 32

Rare Earth Elements (lanthanides)

Question 33

Which of the REEs are most compatible?

Answer 33

The “heavy” REEs

Question 34

Which is the most important mantle phase for REE fractionation?

Answer 34

Garnet

- heavy REEs are significantly more compatible (KD = 5) than LREE (KD = 0.02)