ORE DEP (ULTRAMAFIC TO MAFIC)

Question 1

Deposits related to direct crystallization of magma and usually form in the magma chamber and thus, are deep seated

Answer 1

Magmatic Segragation Deposits

Question 2

Processes that forms or concentrates ore in a Magmatic Segegration Deposit (3)

Answer 2

1) Gravitative Settling
2) Immiscibility
3) Filter Pressing

Question 3

A large sill like body of igneous rocks which exhibit VERTICAL LAYERING or difference in COMPOSITION OR TEXTURE which may cover an area from 100 sq.km to 50,000 sq.km. and several hundred to over a kilometer thickness

Answer 3

Layered Mafic Intrusion

Question 4

What is the average age of the World’s LMIs?

Answer 4

Proterozoic

Question 5

In which landforms do LMIs usually occur?

Answer 5

Stable platform as Intrusion

Question 6

What is the average composition of LMIs?

Answer 6

Gabbro

Question 7

How many LMIs are known in the world?

Answer 7

8

Question 8

How many LMIs have deposits of Cr?

Answer 8

3 of which two are mined from chromium
1) Bushveld , SA
2) Great Dyke, Zimbabwe

Question 9

Only LMI mined for Platinum?

Answer 9

Bushveld

Question 10

Largest Cr Resourve accounting to 70% of the world’s
Largest PGE Resource

Answer 10

Bushveld Igneous Complex

Question 11

In what part of the Busveld Complex are rich in PGEwith Chromite?

Answer 11

Merensky Reef and UG2

Question 12

what type of intrusion is the BIC?

Answer 12

Lopolith

Question 13

Main Chromitite Seam in BIC?

Answer 13

Steelport Main Chromite Seam (UC1)

Question 14

Chromite in Anorthosite deposit?

Answer 14

UG1

Question 15

Largest Ni Resource said to be derived due to complete melting of continental crust due to meteorite impact

Answer 15

Sudbury Crater, Canada

Question 16

Percentage of Intermediate to Calcic Plag

Answer 16

90%

Question 17

Age of most anorthosite

Answer 17

Proterozoic

Question 18

Two types of Anorthosite hosted - Ti

Answer 18

1) LMI fromed by gravitational settling mostly composed of Anorthite
2) Proterozoic Massif or plutons containg andesine to Labradorite (An 35-65)

Question 19

Titaniferous ores in Anorthsoites

Answer 19

Ilmenite - FeTiO3
Rutile TiO2

Question 20

IN what type of magma is an Fe-Ti oxide liquid a residue?

Answer 20

Mafic Magma Differentiation

Question 21

Two Types of Proterozoic Anothoside

Answer 21

1) Ilmenite Rich -Andesine Types
2) Magnetite-Ilmenite Rich - Labradorite Typr

Question 22

One of the two types, SHALLOWLY derived by partial melting or contaminated by LOWER Continental Crust Material

Answer 22

Andesine Type (Ilmenite Rich)

Question 23

Example of Ilmenite rich Anorthosite which is also the largest deposit of Ti in the World

Answer 23

Lac Tio, Quebec, Canada

Question 24

Forms by differentiaion of an anorthosite-gabbro magma

Answer 24

Labradorite Type (Magnetite-Ilmeite Rich)

Question 25

Volatile CO2 Rich
K-Ultramafic rock
Related toPhreatomagmatic Breccia Pipe or Igneous Dike (Diatreme)
dominated by OLIVINE with subordinate mienrals of Mantle Origin

Answer 25

Kimberlites

Question 26

Ca Olivine

Answer 26

Monticellite

Question 27

Potassic Rich Mg-Lamprophyres

Answer 27

Lamproites

Question 28

Age of Productive Kimberlites

Answer 28

80-100 Ma
250 Ma
1000 -1100 Ma

Question 29

Most productive Kimberlites?

Answer 29

Mesozoic

Question 30

Alteration of diamonds in which the microstructure of some carbon and low alloy steels break down after long exposure to elevated temperatures causing material to weaken and be susceptible to cracking failures

Answer 30

Graphitization

Question 31

partial or complete remelting or dissolution of a mineral by magma resulting from change in P,T or Composition

Answer 31

Resorption

Question 32

Major Producers of diamon in the later 1980s

Answer 32

1) South Africa
2) Zaire
3) Russia

Question 33

Majority of Diamond (90%) deposits are derived from?

Answer 33

Placer deposits

Question 34

represent a rapdi, violent upward rush of deep mantle material from the asthenosphere 200 kms below the surface in the form of a diatreme with explosive surface expression

Answer 34

Geological Boreholes (Kimberlites)

Question 35

Methos of Diamond Extraction or recovery which uses ferosilicon in which diamong adhere to greased surface

Answer 35

Haevy Liquid Seperation

Question 36

A method in which a jet of air activated by photocells that perceive visible light flrouresence is emitted in diamond by an x-ray beam as concentrates move along a V belt the air jet popping diamonds and adjacent particles off

Answer 36

Sortex Method

Question 37

Cylindrical Pipelike bodies of Calcite, Dolomite and/or Sierite which are concentrcally znes w

Answer 37

Carbonatites

Question 38

What are the ages of Such deposits?

Answer 38

E.Proterozoic to Recent

Question 39

Two types of Carbonatite

Answer 39

1) Magnetite Apatite Rich - Palabroa
2) REE-Fl-Ba-Rich - Mountain Pass, USA

Question 40

Complex consising of micacaeous pyroxenite, a diopside-phlogopite rock containing 15% Apaatite

Answer 40

Palabora South Africa

Question 41

Which of the three types are most economocically important

Answer 41

Central Pipe (Loolekop)

Question 42

Deposits mined in Carbonatites?

Answer 42

Copper and Phosphate

Question 43

Type of Carbonatites in which Cu occur as chalcopyrite veinlets, low P-Ti-Fe

Answer 43

Transgressive Carbonatite

Question 44

Carbonatite in which Cu is mainly in Bornite dissemination, low P-Ti-Fe

Answer 44

Banded Carbonatite

Question 45

Type of carbonatite in which Cu occurs as Bornite Disseminations w/ minor Chalcopyrite high P-Ti-Fe

Answer 45

Forkstorite