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GLE 2024 (Day 3) > ORE DEP (INTERMEDIATE TO FELSIC) > Flashcards

ORE DEP (INTERMEDIATE TO FELSIC) Flashcards

1
Q

Young Mountain Belts has this composition

A

CalcAlkaline

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2
Q

Intrusion related deposit formed from segegration of magma fluid rich in iron with 4-5% of Phosphorous

A

Igneous Iron Deposit

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3
Q

2 types of Igneous Iron deposits

A

1) Volcanic sedimentary or Sedimentary
2) Intrusive Magmatic Segegation Ore

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4
Q

type of Igenous iron deposit source of important resource and the ferruginous melt vents to the surface as STRATABOUND IRON RICH DEPOSIT

A

Volcanic Sedimentary or Sedimentary

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5
Q

Type of igneous iron deposit in which the ferruginous melt is injected in an intrusive body forming podlike magnetite

A

Intrusive Magmatic Segregation Ore

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6
Q

Most productive Iron Deposit (Magmatic Segregation) in the World

A

Kirunaavara Mine in Sweden

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7
Q

Refers to HIGH PHOSPHOROUS IRON ORES (>2% P)

A

Kiruna type Ore

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8
Q

Large Volume, commonly low - medium grade deposit, primarily of Chalcopyrite and Molybdenite which exhibits HYPOGENE Sulphide and alteration silicate zoning and is temporally and spatially related to a epizonal calc-alkaline - alkaline porphyritic intrusions

Riley
Represent repeated and distinct mode of hydrothermal fluid escape from large intrusions i the crust (Magmatic Hydrothermal)

Large tonnage deposit (1Mt to 10 Gt) of ore in prevasively altered and veined rock in w/c ore minerals are uniformly dissemiated at relatviey LOW grades

A

Porphyry Base Metal Deposits

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9
Q

Mode of Mineralization

A

HF flow along dense network of small fractures through large volume of rock
where mineralization occurs both in the veins and isseminated in altered rock

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10
Q

Important Ore minerals in Porphyry deposist (riley)

A

1) Suflides of Cu and Cu-Fe
Chalcopyr, Bornite, Chalcocite
2) Sulfides of Mo Molybdenite
3) Native Gold (Rare)
4) Oxide of W (Scheelite (ca) and Wolframite (Fe-Mn)
5) Oxide of Sn Cassiterite

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11
Q

Ore Metal Content is dependent on

A

Tectonic Setting
Composition of Host Intrusion COmplex

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12
Q

Conditions of Formation of Porphyry Cu deposits

A

Depth: 2-4 km (Epizonal)
Pressure: <1-2 Kbar
Temp of Formation: 750-850 deg cel
Temp of Mineralization: 250-500 deg cel

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13
Q

How much of the World’s Cu is Prophyry?

A

75%

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14
Q

How much of the world’s Moly is Poprhyry?

A

50%

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15
Q

How much of the world’s Gold is from Porphyry?

A

20%

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16
Q

Grades of Por Cu

A

0.3-1.5% Cu

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17
Q

Grade of Por Au

A

Nil - 1.5 g/t Au

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18
Q

Grades of Por Mo

A

<0.01 -0.04%

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19
Q

Most sticking feature of a porphyry Cu/metal deposit?

A

Large Areas <1-2 sq.km.

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20
Q

Dominant Economic Cu Ore Mineral

A

Chalcopyrite

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21
Q

other Cu Ore

A

Bornite
Covellite
Cuprite
Chalcocite

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22
Q

Main Ore of Mo

A

Molybdenite

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23
Q

Improtant for a lot of deposits esp PCDs to make them economic and substantially higher in Cu Grade

A

Supergene Enrichment

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24
Q

Porphyry Model Variants occuring in Continental Magmatic Arcs and associated with I type porphyritic Intrusive and has low Mo grade

A

Porphyritic Mo

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25
Q

Porphyry Model Variant occuring in Island Arc, few in continental arcs, contain more magetite than Porphyry Cu-Mo

A

Porphyritic Cu-Au

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26
Q

Poprhyry Model Variant occuring in Tectonic and Continental Rifts associated with A-type high silicic porphyritic intrusion with higher Mo Grade

A

Climax Type Mo

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27
Q

ubiquitus and characteristic of the ORE ZONE and of deeper levels of most deposits esp of the barren core beneath and in the interior of the ore shell

Results from metasomatic addition of K+ at high temp

A

Potassic
(Qtz+/-Kfelds +/- Biotite)

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28
Q

Characteristic feature of the Potassic

A

High Conc of Magnetite

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29
Q

Occurs in some deposits peripheral to LOWER DEPTHS limits of the ore zones and NEVER a HOST TO ORE

result of SALINE WaTER infiltration at temp approx 450 deg cel

A

Sodic-Calcic
(Albite/Oligoclase +/- Actinolite +/- Magnetite) No Pyrite

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30
Q

Ubiquitous in Porphyry deposits but forms RELATVIELY LATE in the devt of the Hydrothermal system and OVERPRINTS earlier POTASSIC and CHLORITE SERICITIC zones esp the upper and peripheral (gilid) parts
Sericite is replacement of Kfelds

Results from mod to strong acidic fluids metasomatism involving addition of H+

A

Phyllic (QSP: Qtz +/- Sericite +/- Pyrite)

31
Q

Presence of these features indicates late formation of QSP

A

D-Type Veinlets (Qtz+/-Pyrite) w/c crsos cut protassic altered rocks and A and B Type Veinlets of Potassic Altertaion

32
Q

CAPS the ore zone at some deposits although may also include the ore
has characteristically pale green color
caused by similar fluids that formed the QSP but lower acidity

A

Chlorite-Sericite

33
Q

Locally develop at SHALLOW LEVELS of hydrothermal system ABOVE and PERIPHERAL TO THE PHYLLIC ZONE

forms as a result of intense low temp metasomatism in w/c clay minerals are produced as a result of acid leaching of feldspars

A

Argillic Zone
(Clays Montmorillonite and Kaolinite)

34
Q

Very ubiquitous and is extensively developed around most prophyry deposits w/c can extend up to seveal Km and

results from the addition of volatiles to the host rocks w/o significant metasomations

A

Propylitic
(Epidote Chlorite Calcite)

35
Q

Alteration Zone

A

Spatial Characteristics

36
Q

Potassic

A

Ore Zone

37
Q

Sodic-Calcic

A

Peripheral to the lower limits of the Ore Zone

38
Q

Phyllic

A

Late Formation usually overprints Potassic and Chlorite Sericitic

39
Q

Chlorite-Sericite

A

Capping the ore zone

40
Q

Argillic

A

Above and Peripheral to Phyllic at Shallow zones

41
Q

Propylitic

A

Very Ubiquitous Around the ore body

42
Q

Highest grade ore is found in?

A

Potassic Zone

43
Q

What are the other possible sites of ore?

A

Chlorite-Sericite
Phyllic

44
Q

IN porphry Cu, Ore occurs in?

A

Boundary between Potassic and Phyllic

45
Q

Whats the implication of having mineralization in Phyllic?

A

Overprinting

46
Q

Prograde Alterations Stages

A

Potassic - Propylitic

47
Q

Retrograde Alteartion Stages

A

Phyllic - Advanced Argillic

48
Q

Composition of earliest formed A veins

A

Granular Qtz+Chalco+Molyb+Bornite

49
Q

Composition of B veins

A

Qtz+/-Molyb+/-Chalco+/-pyrite+/-suture

50
Q

Composition of D vens

A

Qtz+/-Pyrite+/-minor Chalco

51
Q

Composition of M veins

A

Magnetite+/-Actinolite

52
Q

Age of common PCDs?

A

Mesozoic to Cenozoic

53
Q

Oldest PCD in PH

A

Cebu (Cret)

54
Q

Other PCDs in PH and ages

A

1) SW Negros and N.Vizacaya - Oligo
2) Luzon and E.Mindanao - M-L.Mio
3)W.Luzon and Cotabato - Plio-Pleisto

55
Q

PCDs are (Epi, Meso) Thermal

A

Mesothermal

56
Q

First model of the PCD based on San Manuel, Kalamazoo, Airzona and is based on SPATIAL relations only and did not recognize Adv. Argillic Alteration and Argilic mistaken to be hypogene instead of suprgene

A

Lowell and Gilbert 1970

57
Q

Established PCD model for the Philippines based on 48 deposits and prospects wherein the causatie intusions are mainly Diroitic and Qtz Dioritic w/c are cylindrical but can be tabular as well. Introduced the Tops and Botoms concept

A

Sillitoe and Gappe

58
Q

Philippine PCDs

A

1) Carmen Copper Atlas Toledo Cebu
2) Philex Sto.Tomas II Benguet
3) Oceana Gold’ Dikindi, Quirino, N vizcaya

59
Q

Advanced PCD Prjects

A

1)Philex’s Boyongan-Bayugo Surigao del N
2) Indophil/Saggitarius Tampakan-S.Cotabato
3) Goldfield’s/Lepanto’s FSE-Benguet
4) St.Augustine’s Kingking - COMVAL

60
Q

Alterations of PMD

A

Potassic w/ less developed Propylitic and Phyllic

61
Q

What separates PMD from Climax Moly?

A

Low Flourine content and Low grade Mo

62
Q

Other name of Poprhyritic Tin which is subvolcanic instrusive complexes containing disseminated, veinlet and breccia contrlolled fine ground cassiterite in qtz porphyry and adjacent rocks

A

Subvolcanic Tin

63
Q

Exploration Markers for PCDs

A

1) Intrusive Complexes
2) Potassic Alteration (Biotite, Magnetite +Kfelds)
3) Cu-Fe Sulfide Mineralisation
4) Qtz. Vein Stockworkds
5) Magneite vein and aleration

64
Q

Alteration sa sides

A

Selvedges

65
Q

aka Replacement Deposits formed by replacement (Contact Metasomatism) of Limestones, Calcareous rocks (Marl or Calc-Schist) or Dolomite as a result of invasion of hyrothermal fluids carrying the high metal concentrations outward from the intrusion

A

Skarn Deposits

66
Q

Most common Skarn Minerals

A

1) Magnetite, Hemmatite
2) Chalcopyrite, Molybdenite Sphalerite and Galena
3) Epidote, garnet, Pyrx
4) Scheelite
5) Gold

67
Q

Characteristic Alteration of Skarns

A

Andradite + Diopside

68
Q

Temp of formation for scarns

A

350-800 deg cel

69
Q

High temp waters

A

Prograde Minerals formed

70
Q

Lower fluid temp

A

Retrograde Minerals formed

71
Q

Skarn within the pluton and Gar>pyx,
or Sedimentary Protolith

A

Exoskarn

72
Q

Skarn within the country Rock Pyx > Gar
Ignours Protolith

A

Endoskarn

73
Q

Philippines Skarns

A

1) Thanksgiving Cu-Au-Zn, Acupan, Benguet
2) Paracale Fe - Cam Norte

74
Q

Also known as Post-Magmatic or Magmatic Hydrootherma which are epigenetic space filling deposits which are coprecipitates in silicate hosts rocks or replacement in carbonate hosts and contains same suites of elements and ore minerals as PCD

A

Cordilleran Vein Type Deposit

GLE 2024 (Day 3) (48 decks)

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