Ore Deposits Geology Week 2asasdsd
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Transcript of Ore Deposits Geology Week 2asasdsd
ORE DEPOSIT GEOLOGY
CONTENTS : WEEK 2
a) ORE STRUCTURES / TEXTURES
Ore Textures (megascopic)
Ore Textures (megascopic)
Replacement textures
Exolution textures
Void-filling textures
Others
b) ORE FORMING MELTS / SOLUTIONS
Magma and Magmatic fluids
Occurences related to crystallisation of magma
Hydrothermal fluids
ORE DEPOSIT GEOLOGY
LEARNING OUTCOMES
(What You will have obtained after the class hour)
You will be able to
• recognise and identify different types of textures , and relate them to ore minerals
• infer types of mineral deposits and mineral paragenesis based on textures
ORE TEXTURES
• Megascopic and three dimentional appearance of ore and gangue minerals making up an ore
• Definiton of megascopic view of an ore. i.e. How it looks, howw we describe the sample
ORE TEXTURES
1) Massive texture
Ores in which samples have rather homogene character & fearure, and usually made up of one ore few minerals
Characteristic of mineral deposits formed usually at high temperatures
Sample:
a) Cr, Fe, Ni-Cu deposits
b) Skarn-type deposits
c) VMS deposits Sudbury Ni-Cu deposit
ORE TEXTURES
Sudbury Ni-Cu yatağı
1) Massive texture
Ores in which samples have rather homogene character & fearure, and usually made up of one ore few minerals
Characteristic of mineral deposits formed usually at high temperatures
Sample:
a) Cr, Fe, Ni-Cu deposits
b) Skarn-type deposits
c) VMS deposits
ORE TEXTURES
Pyrotite; Dereli skarn deposit
1) Massive texture
Ores in which samples have rather homogene character & fearure, and usually made up of one ore few minerals
Characteristic of mineral deposits formed usually at high temperatures
Sample:
a) Cr, Fe, Ni-Cu deposits
b) Skarn-type deposits
c) VMS deposits
ORE TEXTURES
Çayeli VMS deposit
1) Massive texture
Ores in which samples have rather homogene character & fearure, and usually made up of one ore few minerals
Characteristic of mineral deposits formed usually at high temperatures
Sample:
a) Cr, Fe, Ni-Cu deposits
b) Skarn-type deposits
c) VMS deposits
2) Disseminated texture
Textures in which disseminations of minerals accumulate throughout the sample, giving the rock usually homogenous view
Characteristic in podiform cromite deposits
ORE TEXTURES
chromite; Kop podiform chromite deposit
ORE TEXTURES
Chromite; Kop podiform chromite deposit
2) Disseminated texture
Textures in which disseminations of minerals accumulate throughout the sample, giving the rock usually homogenous view
Characteristic in podiform cromite deposits
3) Ring texture
Ore samples in which ore minerals are in the form of rings, bracelets, etc.
Characteristic for podiform type chromite deposits, as well as deposits formed by weathering (bauxite deposits
Chromite; Kop podiform chromite deposit Rings are chromite
Slayt-10
ORE TEXTURES
Slayt-11
ORE TEXTURES
Bauxite: Al ore
3) Ring texture
Ore samples in which ore minerals are in the form of rings, bracelets, etc.
Characteristic for podiform type chromite deposits, as well as deposits formed by weathering (bauxite deposits
4) Banded or laminated texture
Ores in which ore minerals or disseminations of ore minerals accumulate as bands of mm to cm in thickness.
Characteristic in podiform chromite deposits
Slayt-12
ORE TEXTURES
Chromite bands in harzburgite
Slayt-13
ORE TEXTURES
4) Banded or laminated texture
Ores in which ore minerals or disseminations of ore minerals accumulate as bands of mm to cm in thickness.
Characteristic in podiform chromite deposits
Chromite bands in harzburgite
Slayt-14
ORE TEXTURES
Carbonate nodules
5) Nodular texture
Ores in which minerals are formed at the surface and have the kidney-like shape
When nodules are in cm scale, it is called oolitic texture, when in mm scale, then pisolitic texture.
Sedimentary Fe-Mn deposits, travertine depoits
Slayt-15
ORE TEXTURES
Oolitik yumrular
5) Nodular texture
Ores in which minerals are formed at the surface and have the kidney-like shape
When nodules are in cm scale, it is called oolitic texture, when in mm scale, then pisolitic texture.
Sedimentary Fe-Mn deposits, travertine depoits
6) Stockwork texture
Ore minerals are along veinlets cross-cutting each other
ağsal kuvars ve pirit
ORE TEXTURES
7) Brecciated texture
Ores which have undergone deformation following its formation, giving rise to brecciation of rock as well as minerals.
Brecciation takes place after the mineralisation.
Çayeli (Rize) bakır madeninde breşleşmiş cevher kütlesi (pirit, kalkopirit, sfalerit ve gang mineralleri)
ORE TEXTURES
8) Breccia-fill texture
The ores in which ore minerals fill in the gaps formed due to brecciation of rock
i.e. The brecciation is before the mineral occurrence
Found usually in htrothermal deposits
breşleşmiş damar içerisindeki boşlukların galen tarafından doldurulması.
ORE TEXTURES
9) Cellular texture
The ore or rock in which ore and gangue minerals leave voids due mainly to escape of gas during cooling of fuids.
Occurs mainly in replacement type deposits.
Characteristic in epithermal Au deposits
Cerattepe (Kafkasör, Artvin) Au deposit
ORE TEXTURES
Emirli (Ödemiş, İzmir) antimony deposit
ORE TEXTURES
9) Cellular texture
The ore or rock in which ore and gangue minerals leave voids due mainly to escape of gas during cooling of fuids.
Occurs mainly in replacement type deposits.
Characteristic in epithermal Au deposits
CEVHER YAPILARI
10) Dendiritic texture
The ore or any rock in which ore and gangue minerals are deposited or crystallised in the form of branching tree.
Occurs under surficial conditions.
Characteristic for Mn occurences
Manganese dendirites (Abdulaliler Mn occurrence, Maçka, Trabzon
CEVHER YAPILARI
11) Sferulitic texture
Any rock or ore specimen in which minerals are crystallised in the form of spherulites
Occurs mainly during low temperature crystallisation under near-surface conditions
Characteristic for zeolite, chlorite occurences
Stibnite sferülites (Emirli Sb deposit, Ödemiş)
CEVHER YAPILARI
12) Colloidal Texture
Any rock that is formed as a result of colloidal (in the form of a gel) transport of particles.
Occurs as concentric layers around a microscopic particle
ORE TEXTURES
13) Void-filling textures
Characteristic in low temperature, silica enriched (epithermal type Au) deposits.
a) Banded texture,
b) Comb texture,
c) Cokard texture
d) colloform texture
1
A geod (piece of rock which has a large void in it)
ORE TEXTURES
2
Sample opened up a little
ORE TEXTURES
3
Sample opened completely.
ORE TEXTURES
Slayt-28
13) Void-filling textures
a) Banded texture,
Minerals are crystallised along certain zones or bands which may or may not repeat symmetrically Usually occurs in epithermal deposits
Direction of crystallisation
Quartz
Carbonate
ORE TEXTURES
ORE TEXTURES
13) Void-filling textures
a) Banded texture,
1) Symmetricly banded texture
Usually a piece of vein in which crystallisation of minerals takes place symmetrically from the wall to the center of the vein, such as a-b-c-b-a
Gümüşköy Ag deposit (Kütahya).
ORE TEXTURES
Murgul (Artvin) Cu deposit (wall rock-quartz- ametist-quartz-chalcopyrite zones)
13) Void-filling textures
a) Banded texture,
1) Asymmetricly banded texture
Usually a piece of vein in which crystallisation of minerals takes place in the form of asymmetrical zones or bands, such as a-b-c
ORE TEXTURES
13) Void-filling textures
b) Comb texture
A piece of vein in which crystallisation of minerals (usually quartz) takes place as single euhedral crystals growing towards the center of the vein. Characteristic in epithermal systems Olucak (Gümüşhane) Au occurrence
ORE TEXTURES
13) Void-filling textures
c) Cocard Texture
A colloidal-like texture in which mineral precipitation takes place around a megascopic particle or piece of rock. Characterisitic in low T systems
ORE TEXTURES
A colloidal-like texture in which mineral precipitation takes place in te form of symmetric or asymmetric circular or elliptical zones around a microscocopic particle. Characterisitic in low T systems
Çataltepe (Tonya) vein type Pb-Zn deposit
13) Void-filling textures
d) Colloform Texture
ORE TEXTURES
A colloidal-like texture in which mineral precipitation takes place in te form of symmetric or asymmetric circular or elliptical zones around a microscocopic particle. Characterisitic in low T systems
13) Void-filling textures
d) Colloform Texture
MICROSCOPIC TEXTURES
Microscopic Texture refers to the physical appearance or character of a rock, such as grain size, shape, arrangement, and pattern microscopic level. This includes the geometric aspects and relations amongst the minerals. Instead of texture, the term microstructure is preferred by some petrographers
How they are formed? – What they tell us ? 1) Features of hyrothermal fluid 2) Physical characteristic of country rock 3) Physical characteristic of country rock 4) Changes in T and P during crystallisation of minerals
MICROSCOPIC TEXTURES
What they tell us? 1) Temporal relations between gangue and ore minerals
• When a mineral was formed and how it was formed? 2) Mineral paragenesis and succession of mineralisation 3) Formational temperatures of ore and gangue minerals 4) Briefly, conditions under which the ore was formed
Types of microscopic ore textures 1) Ornatım dokuları, 2) Eksolüsyon dokuları 3) Boşluk dolgusu dokuları
MICROSCOPIC TEXTURES
Zerbanos Yayla Cu-Pb-Zn vein, Maçka, Trabzon)
1) Replacement textures
Forms as a result of the interaction of a fluid while it goes through already-formed minerals due to cooling and exchange of ions between the fluids and the minerals
a) Infilling of a fracture by a mineral
MICROSCOPIC TEXTURES
1) Replacement textures
b) Occurrence of a mineral as island or discrete pieces of mineral within
another minerl
Zerbanos Yayla Cu-Pb-Zn
vein, Maçka, Trabzon)
MICROSCOPIC TEXTURES
1) Replacement textures
c) Occurrence of a mineral as island or discrete pieces of mineral within
another minerl
Zerbanos Yayla Cu-Pb-Zn
vein, Maçka, Trabzon)
MICROSCOPIC TEXTURES
1) Ornatım Dokuları:
c) Intrusion of a mineral through another mineral
Replaement of bornite
by chalcopyrite
MICROSCOPIC TEXTURES
1) Replacement textures:
d) Irregularly surrounding of a mineral around / along another mineral
Tetrahedrite and galena
around chalcopyrite
MICROSCOPIC TEXTURES
1) Replacement textures:
e) Encompassing a mineral
A silver mineral around
another silver mineral from
Gümüşköy, Kütahya
MICROSCOPIC TEXTURES
1) Replacement textures:
f) Irregularly intrusion of a mineral within a mineral
Replacement od sphalerite
by tehtahedrite. Bakacak,
Ordu
MICROSCOPIC TEXTURES
2) Exolution textures:
Katı ergiyik içerisinde bulunan bileşenlerin özellikle sıcaklığın
düşmesine bağlı olarak birbirinden ayrlması ve ergiyik içerisinde az
olarak bulunan fazın ana faz içerisinde ayrı olarak kristalleşmesiyle
oluşan doku türüdür. Bu doku türü oluşum sıcaklığının
belirlenmesinde son derece faydalıdır.
Some Exolution textures
Pirotin içinde pendlantit
Kalkopirit içinde kübanit
Sfalerit içinde kalkopirit: 400oC
Stannit içinde sfalerit: 325 oC
Manyetit içinde ilmenit
İlmenit içinde hematit
Hematit içinde ilmenit
Sfalerit içinde kalkopirit:
MICROSCOPIC TEXTURES
2) Exolution textures:
0102030405060708090100
A SixOy B SixOy
T2
T4
T3
T1X3X2
Sıvı (Ergiyik)
X1T2
T4
T3
T1
Karışabilirlik aralığı
T
Homojen
c
a
Moleküler %
MICROSCOPIC TEXTURES
2) Exolution textures:
a) Inclusions:
Chalcopyrite inclusions
within sphalerite.
Zerbanos Yayla Cu-Pb-
Zn vein, Maçka,
Trabzon)
MICROSCOPIC TEXTURES
2) Exolution textures:
b) Lattice texture :
Chalcopyrite lattice in
bornite
MICROSCOPIC TEXTURES
2) Exolution textures:
a) Lattice texture:
MICROSCOPIC TEXTURES
3) Boşluk Dolgusu Dokuları:
Same as megascopic void-filling textures
MICROSCOPIC TEXTURES
3) Boşluk Dolgusu Dokuları:
1) Microveins of a mineral within another mineral
Tetrahedrite vein within
chalcopyrite
Zerbanos Yayla Cu-Pb-
Zn damarı, Maçka,
Trabzon)
MICROSCOPIC TEXTURES
3) Void-filling texture
2) Veinlets
Tetrahedrite-veinlets in
chalcopyrite
Zerbanos Yayla Cu-Pb-Zn
vein, Maçka, Trabzon)
MICROSCOPIC TEXTURES
3) Boşluk Dolgusu Dokuları:
Breccia-infill texture
CEVHER DOKULARI
3) Void-filling texture
4) Colloform texture
CEVHER DOKULARI
4) Other Textures
a) Needle-like textures
CEVHER DOKULARI
4) Other Textures
b) Kink-banded textures
Stibnite kink-bands (Gümüşler, Niğde).
c) Dissolution textures
Dissolution of pyrite (Gümüşler, Niğde).
Pyrite
Pyrite
lst
lst
lst
Barite
Sphalerite+galena+fahlore
2 cm
Limestone
kçt
kçt
kçt
kçt
kçt
ORE: Mineral Paragenesis - 1
ORE: Mineral Paragenesis - 2
1
2
3
5
1
2 1
5
3
6
4
ORE: Mineral Paragenesis - 3
4 6 1
5 4
2
1
4
1
3 3’
3
3’
6
4
ORE: Mineral Paragenesis - 4
%45,941 Cu, %16,863 Te, % 9, 046 As, % 0,533 Zn, % 0,44 Ag, %0,276 Fe, % 25,58 S
0, 74 at. % Cu+Fe+Zn+Ag, 0,263 at. % Te+As+Sb, 0,768 at. % S
Cu12Te4S13 : Goldfieldit
Mik
rop
rob