Geophysics review

Question 1

4 subdisciplines of geophysics

Answer 1

global, exploration, geotechnical & environmental, forensic

Question 2

subdiscipline focused on the structure of the earth

Answer 2

global geophysics

Question 3

3 sub-subdisciplines under exploration geophysics

Answer 3

mining, petroleum, hydrocarbon, groundwater studies, geothermal energy exploration

Question 4

subdiscipline focused on detection of ore bodies

Answer 4

mining geophysics

Question 5

subdiscipline focused on structures that trap oil

Answer 5

petroleum geophysics

Question 6

subdiscipline focused on the depth and configuration of an aquifer

Answer 6

groundwater studies

Question 7

3 focuses of geotechnical and environmental geophysics

Answer 7

site investigations, contamination studies, archeological investigations

Question 8

focus of geotechnical & environmental geophysics that involves mechanical properties and depth

Answer 8

site investigations

Question 9

focus of geotechnical & environmental geophysics that involves detection and flow direction

Answer 9

contaminant studies

Question 10

subdiscipline that involves locating or detecting the presence of subsurface structures or bodies and determine their depth, size, shape and physical properties

Answer 10

exploration geophysics

Question 11

what is being explored for in exploration geophysics?

Answer 11

features of bodies related to mineral deposits, energy or groundwater resources

Question 12

what are the 6 geophysical methods?

Answer 12

gravity, magnetics, seismic reflection, seismic refraction, electrical (georesistivity, induced polarization), ground penetrating radar

Question 13

the 3 anomaly profiles for magnetic geophysical method

Answer 13

poles, mid-latitude, equator

Question 14

geophysical method that makes use of lines of current flow throughout the earth

Answer 14

electrical resistivity method

Question 15

5 main physical properties involved in geophysical surveys

Answer 15

density, magnetics susceptibility, elasticity, conductivity, relative dielectric permittivity

Question 16

what property is measured an @ what units for magnetic geophysical method?

Answer 16

magnetic susceptibility (dimensionless); magnetic field strength (Gauss = 10^-4 T, Gamma = nT

Question 17

what property is measured an @ what units for gravity geophysical method?

Answer 17

density (kg/m^3, g/m^3); gravitational field strength (mGal = 10^-3 cm/s^2)

Question 18

what property is measured an @ what units for seismic geophysical method?

Answer 18

velocity (m/sec, km/sec, m/sec)

Question 19

what property is measured an @ what units for electrical geophysical method?

Answer 19

resistivity: ohm-meters
conductivity: mho/m = Siemens/m (S/m)

Question 20

a physical property contrast (vertical or lateral)

Answer 20

geophysical anomaly

Question 21

geophysical method that studies changes in strength of geomagnetic field

Answer 21

magnetic

Question 22

geophysical method that studies the travel times of reflected or refracted seismic waves

Answer 22

seismic

Question 23

geophysical method that studies resistance and potential differences

Answer 23

electrical

Question 24

geophysical method that studies the changes in strength of the earth’s gravitational field

Answer 24

gravity

Question 25

geophysical method that studies the reflection of electromagnetic waves

Answer 25

GPR

Question 26

5 points in qualitative interpretation of anomalies

Answer 26

* distribution of highs and lows * trend or orientation of highs and lows * shape of anomalies (circular, linear) * amplitude or wavelength of anomalies * breaks or discontinuities in the anomalies

Question 27

examples of minerals explored for in exploration geophysics

Answer 27

gold, copper, massive sulfides, iron, chromite, laterite

Question 28

examples of hydrocarbons explored for in exploration geophysics

Answer 28

oil, gas, coal, gas hydrates

Question 29

3 stages of geophysical surveys

Answer 29

reconnaissance, detailed exploration pt 1, detailed exploration pt 2

Question 30

stage in geophysical surveys that use airborne geophysics or ground surveys

Answer 30

reconnaissance

Question 31

stage in geophysical surveys that use ground geophysics and borehole logging

Answer 31

detailed exploration

Question 32

5 mineral districts in the phils

Answer 32

Baguio-Mankayan Gold district Paracale Gold district Masbate Gold district Surigao Gold district Masara Gold district

Question 33

5 kinds of mineral deposits in the phils

Answer 33

epithermal porphyry Cu/Cu-Au volcanogenic massive sulfides nickel laterite chromite

Question 34

tectonic settings of mineral deposits in the phils

Answer 34

extensional, compressional, transtensional

Question 35

depositional environment of mineral deposits

Answer 35

volcanic caldera, dome complex, oceanic terrane

Question 36

age of mineralization of mineral deposits

Answer 36

Mesozoic, Cenozoic

Question 37

host/associated rock types of mineral deposits

Answer 37

volcanic rocks, ultramafic rocks, acidic rocks

Question 38

deposit forms of mineral deposits

Answer 38

veins, massive, replacement

Question 39

ore controls of mineral deposits

Answer 39

hydrothermal breccia pipes, fractures, extensional faults

Question 40

host/associated rock types of epithermal Au-Ag-Cu high sulphidation deposits

Answer 40

andesite to dacite and rhyodacite

Question 41

deposit form of epithermal Au-Ag-Cu high sulphidation deposits

Answer 41

veins and massive sulphide replacement pods and lenses, stockwork and breccias

Question 42

ore mineralogy of of epithermal Au-Ag-Cu high sulphidation deposits

Answer 42

pyrite, enargite/luzonite, chalcocite, covellite, bornite, gold, electrum

Question 43

gangue mineralogy of epithermal Au-Ag-Cu high sulphidation deposits

Answer 43

pyrite and quartz predominate

Question 44

alteration mineralogy of epithermal Au-Ag-Cu high sulphidation deposits

Answer 44

quartz, kaolinite/dickite/alunite/barite/hematite

Question 45

ore controls of epithermal Au-Ag-Cu high sulphidation deposits

Answer 45

caldera ring, darial fractures, fracture serts and faults and breccias in and around intrusive centers

Question 46

geophysical signature of epithermal Au-Ag-Cu high sulphidation deposits

Answer 46

magnetic lows in hydrothermally altered (Acid-leached) rocks, gravity contrasts may mark boundaries of structural blocks

Question 47

other exploration guides for epithermal Au-Ag-Cu high sulphidation deposits

Answer 47

- deposits are found in 2nd order structures adjacent to crustal-scale fault zones, normal and strike-slip, as well as local structures associated with subvolcanic intrusions

Question 48

usual lithology for mineral exploration

Answer 48

sedimentary rocks, volcanic rocks, intrusive complex, granitic plutons, gneiss and granite

Question 49

what alterations indicated magnetic lows and magnetic highs in mineral deposits

Answer 49

magnetic low = hydrothermal alteration magnetic high = potassic alteration

Question 50

how does magnetite affect magnetic anomalies

Answer 50

magnetic highs = presence of magnetite magnetic lows = alteration destroyed magnetite

Question 51

what is studied in groundwater exploration

Answer 51

depth and configuration of aquifer

Question 52

what is studied in petroleum exploration

Answer 52

structures that trap oil

Question 53

what is studied in non-mineral exploration for environmental problems

Answer 53

leaking underground storage tanks and drunks; contamination studies (detection, flow direction)

Question 54

what is studied in forensic geophysics

Answer 54

locate missing buried bodies locate clandestine graves or disturbed ground locate buried weapons or evidence of crime