Ore Deposits Geology Week 1

transcript

ORE DEPOSITS

CONTENTS OF THE WEEK 1

INTRODUCTION – Definitions

– General Definitions

– Genetic Definitions

– Mineralogic Definitions

Slayt - 1

INTRODUCTION

For Details of the Ore Deposits Geology • http://obs.ktu.edu.tr/en • http://www.katalog.ktu.edu.tr/DersBilgiPa

keti/bolum.aspx?pid=5&lang=1 – Syllabus – Study material – Exams, quizzes, labs, etc.

INTRODUCTION

Objective of the course: The course • provides students with basic knowledge of processes

leading to formation of mineral deposits, • teaches students practical tips related to mineralized

and unmineralized samples, and for recognizing hydrothermal alteration patterns,

• teaches students known models of mineral deposits with best examples from around the globe

INTRODUCTION Literature • Akçay, M. 2004; Maden yatakları, yayınlanmamış ders notları,

KTÜ, Trabzon - Unpublished lecture notes • Kırıkoğlu, S., 2002; Maden Yatakları, İTÜ • Akçay, M. 2009; Power point presentations related to weekly

content of the course. http://www.makcay.ktu.edu.tr/dersler • Temur, S. 2001; Metalik maden yatakları. Nobel Yayınları,

Ankara • Gökçe, A., 2000; Maden Yatakları. Cumhuriyet Üniversitesi

Yayınları No: 85, Sivas • Guilbert, J.M, Park, C.F.,Jr., 1986; The Geology of Ore

Deposits. Freeman and Coampany, New York

Definitions: General Terms

Any kind of rock, mineral and their assemblage that have an economical value and that can be produced with a profit.

Metallic ores Gold, Silver, Copper

Non-metalic Ores

Industrial raw materials Kil yatakları, mermer, vs.

Energy materials

Ornamental stones Opal, zümrüt, vs.

Fossil fuels Oil, coal

Geothermal energy

Thermal waters

Nucleer energy U and Th deposits

Metallic Ore:

Any kind of resourcef rom which metal production is made through metallurgic processes following extraction of ore from the mine area.

Industrial raw materials

Any kind of resource that can be used as they are extracted from the mine site, or following through minor physical and chemical processes that will not change the composition of the extracted material.

Genel Terimler Ornamental stones

Any mineral which is resistant to chemical and physical weathering and decay, and which has alluring and appealing colour and textures (diamond, garnet, saphire, etc).

Garnet

Rhodocrosite

Ore Mineral Any mineral within a metallic ore bodywhich can be produced with a profit .(e.g. Chalcopyrite, galena, barite, etc.)

Gangue mineral Any mineraal within a metallic ore body which cannot be produced with a profit at the time of mining. (e.g. pyrite, (suphide), barite (sulphate), quartz (silicate)

Stibnite

Unprocessed Ore

An extracted ore which has just been extracted from the mine site, but has not yet undergone any chemical, mineralogical or metallurgical processing.

Reserve: Total mass of an ore body given in ton.

Grade: the amount of any mineral or compound within an ore body expressed in g/ton, %, etc.

A) Syngenetik ? B) Epigenetik ?

Syngenetic Ore Deposit

An ore deposit which has been formed together with the host rock, indicating that the ore minerals and the rock hosting them are contemparenous.

Genesis = Formation= Origin

SYN = Contemparenous, same,

EPİ = Formation after the host

Epigenetic Ore Deposit

An ore deposit which has been formed after the formation of the host rock showing that the rock pre-dates the ore minerals.

Definitions: Genetic Terms

Mineralogic Terms

Paragenesis:

Mineral assocation present within an ore body. All the minerals composing the mineralogy of the ore deposit

Succession

The sequence or timing of formation of minerals present within an ore body.

Morhology of Mineral Deposits

A) Regular Ore Deposits 1) Stratiform deposits 2) Strata-bound deposits 3) Vein type deposits 4) Lense-shaped deposits. B) Semi-Regular Ore Deposits 1) Pipes and mantos C) Irregular Ore Deposits 1) pods 2) veinlets 3) Disseminations

Regular Ore Deposits An ore occurrence that can be followed easily along strike, and that has almost constant orregularly chanhing width and thickness

UltrabazikKromit

Manyetit

Kireçtaşı Galena, sphalerite

1) Stratiform Deposits Ore formations characterised by layers or beds parallel to bedding or magmatic layering. The ratio of length and width to thickness are very high. Found mainly in sedimentary and magmatic ore deposits such as chromite deposits. Ore formation in these deposits is syngenetic.

Regular Ore Deposits 2) Strata-bound deposits • Similar to stratiform deposits in appearance • But their formation is epigenetic • They form zones parallel or sub-parallel to the bedding or schistocity of

sedimentary and mertamorphic rocks, respectively. Ore depoists found along marble-schist contacts such as Sb-Au deposits in Turkey can be given as an example.

Limestone

Schist

Stibnite, Cinnabar, Gold

Schist

Stibnite, Cinnabar, Gold

3) Veins Thickness is much less

than other dimensions

Both surfaces parallel to each other,

They are placed by cutting through the rock alng faults and joints

Has an epigenetic occurrence

Can be considered as faults

Regular Ore Deposits

Fault or crack / joint

Basalt

Contact between vein and wall rock

Ore zone

Hanging wall Footwall

3) Veins

Slayt-20

a) Enrichment zones in veins: Thickness of the veins may change based on the lithological variations. More ductile lithologies are broken more easily and develop well developed fracture zones. Units with plastic behaviour, however, prevent the fractures to develop.

Kumtaşı

Ş e y l

K u m t a ş ı D i r e n ç s i z

D i r e n ç l i

3) Veins

a) Crosscutting fractures

Bazalt

b) Enrichment due to changing wall rock lithology

Granit

Regular Ore Deposits Enrichment zones in veins:

1) Step-like veins

Daha azdayanımlı yankayaç

2) Room-like veins

Kireçtaşı

3) Lense-like veins

4) wedge-like veins

5) sward-like veins 6) Groove/ saddele veins

Semer damar

Oluk damar

Regular Ore Deposits Vein types: As to be seen below, veins are divided into groups based

on their shapes. Therefore the names are variable

Regular Ore Deposits 4) Lenses Characteristic in pegmatitic and exhalative ore deposits, they have a lense-like shape and show thinning in every. Vary in size. Their length is bigger than their width and thickness.

Ore deposits whose continuity is not as well-developed as regular deposits. However, they can be traced along strike and mining plan is made rather easily in such deposits.

Kimberlite pipe

Wall Rock

Pipes and Mantos Pipes are cylindirical or tube shaped vertical or semi-vertical enrichment zones which has an oval horizontal section and decrease in thichness with depth. They are developed along intersection zones of faults, large joints and dykes. Au, Pt, Sn and diamond can be mined from such deposits. e.g. kimberlite pipes in S . Africa. Mantos are the horizontal or semi-horizontal pipes

Semi-Regular Ore Deposits

Ore deposits with variable directions and dimensions, and no geometrical shape. Therefore difficult to follow during mining. Necessitatess a lot more drilling during feasibility stage to be able determine the boundaries of ore.

Stacks or pods Ore zones with no geometrical shape. They may have variable and abrubtly changing boundaries Known as stocks. Characteristic in metasomatic ore deposits developed mainly in karstic zones. Some chromite deposits also have stack-like occurrence.

Irregular Ore Deposits

Ore deposits with variable directions and dimensions, and no geometrical shape. Therefore difficult to follow during mining. Necessitatess a lot more drilling during feasibility stage to be able determine the boundaries of ore. Stacks or pods

Morhology of Mineral Deposits Irregular Ore Deposits

Veinlets or Stockworks Ore deposits in which ore minerals are along tiny and mm to cm—thick veinlets cutting each other. The orientation od veinlets are usually parallel to the main fracture zones. They are also known as stockwork deposits. Characteristic in porphyry type deposits.

Irregular Ore Deposits

Mikrodiyorit

Veinlets Ore deposits in which ore minerals are along tiny and mm to cm—thick veinlets cutting each other. The orientation od veinlets are usually parallel to the main fracture zones. They are also known as stockwork deposits. Characteristic in porphyry type deposits.

Irregular Deposits

Disseminations Ore minerals are scattered as individual inclusions or small clusters of inclusions. Such inclusions or clusters usually follow microscopic joints which are parallel to main megascopic joints present in the rock

Murgul Cu yatağı

Irregular Deposits

Ore Deposits Geology Week 1

Documents