How can minerals deposits be formed; GEOLOGICAL PROCESSES; Ore Fluids; Ore Forming Processes; Concentrating Processes; Magmatic mineral deposits; Residual mineral deposits ; Placer deposits; Sedimentary mineral deposits; Metamorhogenic mineral deposits; Hydrothermal mineral deposits ; Magmatic Deposits Cumulate deposits: fractional crystallization processes can concentrate metals (Cr, Fe, PGE, Pt, Ni, Ti, Diamond )) Pegmatites : late staged crystallization forms pegmatites and many residual elements are concentrated (Li, Ce, Be, Sn, U, Rare Earths (REE), Feldspar, Mica, Gems). magmatic deposits; Mode of Formation of Magmatic Ores Deposits; Mode of Formation of Orthomagmatic Ores ; Fractional Crystallization (or Crystal fractionation ); Magmatic (or Liquid ) Immiscibility; Simple crystallization without concentration (Dissemination); Segregation of early formed crystals; (Layer Types); Injection of material concentrated elsewhere by differentiation Residual liquid segregation; Residual liquid injection; Immiscible liquid segregation; Immiscible-liquid-injection; Early magmatic deposit; Late magmatic deposit; Types of Magmatic Ore Deposits:Chromite; Fe-Ti (± V) oxides; Ni – Cu – Fe (± Pt) sulfides; Platinum Group Elements (PGEs); REE, and Zr in Carbonatites; Diamond in kimberlites.

1. LECTURE 3:
MAGMATIC MINERAL DEPOSITS
Prof. Dr. Hassan Z. Harraz
Geology Department, Faculty of Science, Tanta University
hharraz2006@yahoo.com
Spring 2020

2. The Rock Cycle
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3. 1) GEOLOGICAL PROCESSES
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4. 2) Ore Fluids
2.1) Ground water:
✓Meteoric Water
✓Connate Water
2.2) Sea water
2.3) Magmatic Fluids
2.4) Hydrothermal Fluids
2.5) Magmatic-Hydrothermal Fluids
2.6) Metamorphic water
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5. 3) Ore Forming Processes
Most ore-forming processes on earth are related to water (no water on
the Moon, other processes?)
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6. 4) Concentrating Processes
➢Leaching
➢Weathering and sedimentation
➢Supergene enrichment (water table effect, due to
descending fluids)
➢Hypogene enrichment (due to ascending fluids)
➢Metamorphism (usually disperses)
➢Granitization
➢Vein migration and changes in T, P, fO2, pH etc.
➢Gravity settling
➢Filter pressing
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7. 5) How can minerals deposits be formed?
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8. i) Deposits from igneous processes
ii) Deposits from magmatic-hydrothermal
processes
iii) Deposits from hydrothermal processes
iv) Deposits by surficial or supergene processes
v) Deposits from sedimentary processes
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9. 5.1) Ore Deposit Types
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10. 5.2) Ore usually formed by various processes in different environments
Example: Copper Ore Deposits
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11. I) Endogenous (Internal)
processes
(Radioactive, internal heat driven
largely)
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12. 12

13. WHAT ARE MAGMATIC DEPOSITS?
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14. MODE OF
FORMATION
OF
MAGMATIC
ORE
DEPOSITS Desirable element preferentially
concentrated into low-volume melt.
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15. MODE OF FORMATION OF MAGMATIC ORE DEPOSITS
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16. Formation of Magmatic Mineral Deposit by Crystal Settling
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17. Mode of Formation of Orthomagmatic Ores:
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18. Mode of Formation of Magmatic Ores Deposits:
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19. Magmatic Deposits: Immiscibility
➢Separation and non-mixing of liquid phases of a
magma (e.g., A sample of nickel-bearing rock from
Nickel deposits of Sudbury).
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20. Schematic representation of processes associated with the formation
of layered mafic complexes
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21. 21

22. Classification of Magmatic Ore Deposits
❑The magmatic deposits are classified into
two major groups:
(i) Early magmatic deposit, and
(ii) Late magmatic deposit.
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23. CLASSIFICATION OF MAGMATIC DEPOSITS
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24. Early Magmatic Deposits
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25. Late Magmatic Deposits
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26. 26

27. I) CHROMITE DEPOSITS
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28. http://pubs.usgs.gov/bul/b2156/b2156.pdf
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29. 29
Formation of stratiform
chromite:
Chromite, the main ore
mineral of chromium,
crystallizes from a magma
and, because it is denser
than the magma, sinks to the
bottom and accumulates in a
process called crystal
settling.

30. 30

31. 31
Plutonic rock bodies of basaltic composition with stratiform
chromite that are layered or banded (Bushveld chromitite).

32. STRATIFORM VS PODIFORM Chromite DEPOSITS:
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33. Disseminated
texture
Textures in which
disseminations of
minerals
accumulate
throughout the
sample, giving the
rock usually
homogenous view
Characteristic in
podiform chromite
deposits
chromite; Kop podiform chromite deposit
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34. II) Ni – Cu – Fe (± Pt) sulfide deposits in Ultramafic and Mafic rocks
(or Ni – Cu – Fe (± Pt) Type Magmatic Massive Sulphides)
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35. II) Ni – Cu – Fe (± Pt) sulfide deposits in ultramafic and mafic rocks
(or Ni – Cu – Fe (± Pt) Type Magmatic Massive Sulphides)
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36. Platinum Group Elements (PGEs)
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37. Orthomagmatic PGE-Ni-(Cu)
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38. 38

39. 39

40. 40

41. The Bushveld Complex, South Africa (2.1 Ga)
Simplified geologic
map and cross section
of the Bushveld
Complex ( After
Willemse, 1964;
Wager and Brown,
1968; Irvine et al.,
1983).
The biggest Layered
Mafic Intrusions (LMI):
300-400 km x 9 km
The Red Granite
intruded 50-100 Ma
afterwards
The Bushveld is the
source of most of the
world’s : Pt, Pd, Cr &
V
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42. 42

43. III) Fe- Ti oxides associated with Precambrian Anorthosites, and Magnetite deposits (Fe-
P) associated with Alkalic Volcanic Complexes.
III) Fe-Ti (± V) Oxides
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44. B) Magnetite – Apatite deposits in alkalic volcanic complexes (Kiruna type)
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45. Bedded hematite ash and lappilli. This deposit is composed of loose,
uncemented, material that can be dug out by hand..
EL LACO , Quebec Magnetite Deposit
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46. 46

47. IV) REE, and Zr in Carbonatites
(or ; Carbonatites and their associated ore deposits)
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48. V) Diamond in kimberlites
Diamond Graded
Magmatic - Special
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49. Diamond Reserves
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50. 50

51. Diamond Locations
At these depths stable form of carbon switches from
graphite to Diamond
Red and Dark Green Mark the
Spot
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52. Kimberlite Pipes and Diamonds
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53. Kimberlite does not make diamonds
It drags them
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54. Deposits from Magmatic-Hydrothermal Ore Forming Processes
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55. 55
Pegmatite

56. I) Pegmatite Ore Deposits
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58. Pegmatite ore deposits may be especially valuable if the rocks are coarse-
grained, so that the minerals of interest are more easily removed.
Gemstones, such as beryl, aquamarine, tourmaline, ruby, and emerald, are
very rare and are found as pegmatites.
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60. II) Greisens and Associated Sn – W Deposits
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61. Follow me on Social Media
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https://www.linkedin.com/in/hassan-harraz-3172b235
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