Lec 7 - Geothermometry, Geobarometry, And Istope Studies

Question 1

What are your persitent minerals

Answer 1

Pyrite and gold

Question 2

At surface conditions: oxides suffers ______, and sulfides suffers __________

Answer 2

Oxides suffers least and sulfides suffers most

Question 3

• greek word means “born beside”
• used to describe any assemblage of ore minerals, with or without gangue, formed at the same time and normally in equilibrium.

Answer 3

Paragenesis

Question 4

A collection or gathering of minerals or rock

Answer 4

Assemblage

Question 5

Having a connection or resemblance with other mineral in certain temperature and pressure regime

Answer 5

Associated

Question 6

Minerals that yield information as to the temperature of their formation

Answer 6

Geothermometers

Question 7

The measurement of lavas, fumaroles, and hot springs

Answer 7

Direct Measurement

Question 8

Indicate the maximum crystallization temperatures

Answer 8

Melting points

Question 9

Hot spring measurements

Answer 9

Opal, gypsum, stibniteu

Question 10

Some minerals lose volatile content at certain temperatures

Answer 10

Dissociation

Question 11

Transformation of some minerals’ crystal sytem to naother is temp dependent

Answer 11

Inversion points

Question 12

Minerals that form solid solutions unmix at specific temps to yield distinguishable intergrowths

Answer 12

Exsolution

Question 13

Similar to inversion and exsolution but applies more specifically to native minerals

Answer 13

Recrsytallization

Question 14

Crystals trap gases or liquids which they crystallizes

Answer 14

Fluid inclusion

Question 15

Fluid inclusions in cavities of crystals indicate the ______________ of formation of the crystals by the amount of contraction of the liquid, assuming the liquid originally filled the cavity

Answer 15

Approximate Temperature

Question 16

Heating the sample until an heterogenous fluid inclusion homogenizes

Answer 16

Minimum Temperatures of Formation

Question 17

By freezing-point depression method. This temp is then used to read off the solution composition from a graph or calculated from equations

Answer 17

Total NaCl-equivalent salinity of the fluid

Question 18

The minimum melting point

Answer 18

Eutectic point

Question 19

Inclusion is opened up and direct tests are made on the liquid by optical-physical properties

Answer 19

Composition of Ore-Bearing fluid

Question 20

Inclusions formed in growing crystals with no leakage

Answer 20

Primary

Question 21

Inclusions that formed With fractures and sealed again,records comdition of later hydrothermal stage. Formed after primary crystallization

Answer 21

Secondary

Question 22

Looks like secondary, but the host crystal was fractured as the crystal was growing

Answer 22

Pseudosecondary

Question 23

It is important to remember always that the fluid inclusions in a mineral provide information only on the fluids present at the time of sealing of the inclusion, whether that be during the growth of the host crystal or during rehealing of a later fracture

Answer 23

Edwin Roedder, 1977

Question 24

The estimation of pressure conditions at which a geologic material formed.

Answer 24

Geobarometry

Question 25

Determine the source and composition of ore-bearing fluids/components, age of mineral deposit, dteermine temperature and other conditions of deposition, and to establish the degrees of bacteriological involvement in certain ore-forming processes

Answer 25

Isotope studies

Question 26

Does not decay into other elements

Answer 26

Stable isotope

Question 27

Able to classify source of water in hydrated alteration minerals

Answer 27

Oxygen (18) and Hydrogen (D) isotopes

Question 28

It pinpoints the source of sulphur,

Answer 28

Sulphur (35 and 34) isotopes

Question 29

(Decay) into daughter istopes at known rates

Answer 29

Radioisotopes

Question 30

Amount of time needed for one-half of a radioactive parent to decay into daughter isotopes

Answer 30

Half-life

Question 31

Establish the time of origin of a rock by a momount of common lead it contains

Answer 31

Uranium-Thorium-Lead (U-Th-Pb)

Question 32

The single set of lead isotope ratios throughout the earth mass during the formation of earth

Answer 32

Primitive lead