Geophysics review Flashcards

1
Q

4 subdisciplines of geophysics

A

global, exploration, geotechnical & environmental, forensic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

subdiscipline focused on the structure of the earth

A

global geophysics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

3 sub-subdisciplines under exploration geophysics

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

subdiscipline focused on detection of ore bodies

A

mining geophysics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

subdiscipline focused on structures that trap oil

A

petroleum geophysics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

subdiscipline focused on the depth and configuration of an aquifer

A

groundwater studies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

3 focuses of geotechnical and environmental geophysics

A

site investigations, contamination studies, archeological investigations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

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

A

site investigations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

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

A

contaminant studies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

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

A

exploration geophysics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is being explored for in exploration geophysics?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the 6 geophysical methods?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

the 3 anomaly profiles for magnetic geophysical method

A

poles, mid-latitude, equator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

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

A

electrical resistivity method

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

5 main physical properties involved in geophysical surveys

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

a physical property contrast (vertical or lateral)

A

geophysical anomaly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

geophysical method that studies changes in strength of geomagnetic field

A

magnetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

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

A

seismic

23
Q

geophysical method that studies resistance and potential differences

A

electrical

24
Q

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

A

gravity

25
Q

geophysical method that studies the reflection of electromagnetic waves

A

GPR

26
Q

5 points in qualitative interpretation of anomalies

A
  • 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
27
Q

examples of minerals explored for in exploration geophysics

A

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

28
Q

examples of hydrocarbons explored for in exploration geophysics

A

oil, gas, coal, gas hydrates

29
Q

3 stages of geophysical surveys

A

reconnaissance, detailed exploration pt 1, detailed exploration pt 2

30
Q

stage in geophysical surveys that use airborne geophysics or ground surveys

A

reconnaissance

31
Q

stage in geophysical surveys that use ground geophysics and borehole logging

A

detailed exploration

32
Q

5 mineral districts in the phils

A

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

33
Q

5 kinds of mineral deposits in the phils

A

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

34
Q

tectonic settings of mineral deposits in the phils

A

extensional, compressional, transtensional

35
Q

depositional environment of mineral deposits

A

volcanic caldera, dome complex, oceanic terrane

36
Q

age of mineralization of mineral deposits

A

Mesozoic, Cenozoic

37
Q

host/associated rock types of mineral deposits

A

volcanic rocks, ultramafic rocks, acidic rocks

38
Q

deposit forms of mineral deposits

A

veins, massive, replacement

39
Q

ore controls of mineral deposits

A

hydrothermal breccia pipes, fractures, extensional faults

40
Q

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

A

andesite to dacite and rhyodacite

41
Q

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

A

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

42
Q

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

A

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

43
Q

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

A

pyrite and quartz predominate

44
Q

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

A

quartz, kaolinite/dickite/alunite/barite/hematite

45
Q

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

A

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

46
Q

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

A

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

47
Q

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

A
  • 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
48
Q

usual lithology for mineral exploration

A

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

49
Q

what alterations indicated magnetic lows and magnetic highs in mineral deposits

A

magnetic low = hydrothermal alteration
magnetic high = potassic alteration

50
Q

how does magnetite affect magnetic anomalies

A

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

51
Q

what is studied in groundwater exploration

A

depth and configuration of aquifer

52
Q

what is studied in petroleum exploration

A

structures that trap oil

53
Q

what is studied in non-mineral exploration for environmental problems

A

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

54
Q

what is studied in forensic geophysics

A

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