week 1 - 4 igneous rocks

Question 1

what is younging direction

Answer 1

the direction in which beds get younger

Question 2

cross bedding are how big

Answer 2

> 1m

Question 3

cross ripple lamination are how big

Answer 3

<1m

Question 4

what are syn depositonal minor structures and examples

Answer 4

used to determine the strata

graded bedding: sorted material with coarse to fine up top

Pillow lava: in the form of distored globular masses

Question 5

what are post depositional primary structures and examples

Answer 5

used to determine the strata

load clasts: sand can load mud below - bulbous

flame structures: mud pushed up by load clasts

convolute bedding: laminae are contorted by high velocity currents

mud cracks and burrows

Question 6

what is strike, dip and dip direction

Answer 6

strike: direction of a horizontal line in the plane (3 numbers)
dip: inclination of plane, measured down from horizontal (2 numbers)
dip direction: compass sector toward which the plane dips (3 numbers)

Question 7

what is apparent dip

Answer 7

dip angle in a section not normal to the strike

Question 8

what are outliers

Answer 8

younger rocks surrounded by younger rocks, common with erosional, fold, fault and depositional outliers

Question 9

what are inliers

Answer 9

older rocks surrounded by younger, common with erosional, fold and fault outliers

Question 10

a paraconformity is what

Answer 10

an unconformity with no obvious erosional surface (flat, clear boundary)

Question 11

a disconformity is

Answer 11

an erosional surface between sequences

Question 12

a non conformity consists of what

Answer 12

sedimentary layer ontop of igneous/metamorphic layer (blob like, intrusive)

Question 13

how to recognise unconformities

Answer 13

sedimentary: conglomerates, weathered surfaces, truncation of bedding planes, surfaces altered by burrowing, boring or cementation in hard grounds and surfaces that show relief due to erosional episode

paleontological: one or more faunal zones missing

structural: trucated dykes or faults, gently discondant dups above and below unconformity

Question 14

what are concordant intrusions

Answer 14

lavas, tuffs, sills and lacoliths

Question 15

what are disconcordant intrusions

Answer 15

dykes, radial dyk, cone sheets, and plugs

Question 16

what are the 5 steps in identifying faults

Answer 16

1. trends that share orientation
2. displacement type (apparent or true)
3. relative ages
4. sets
5. systems

Question 17

what are the different types of ore deposition

Answer 17

placer, orogenic, epithermal, porphyry, VMS synsedimentary and hydrothermal

Question 18

what are the fluid sources of hydrothermal deposits

Answer 18

magmatic, metamorphic, meteroic, connate and seawater

Question 19

what is stratabound

Answer 19

bound within stratigraphic layer, often limestone or organic rich sediments (chemically reactive)

Question 20

what is stratiform

Answer 20

having the form of stratigraphic layering such as an evaporative deposits

Question 21

examples of epigeneitc deposits

Answer 21

same age as intrusion such as a vein of gold or porphyry

Question 22

what range is gentle fold

Answer 22

180 - 120

Question 23

what range is open fold

Answer 23

120 - 70

Question 24

what range is closed fold

Answer 24

70 - 30

Question 25

what range is tight fold

Answer 25

30 - 5

Question 26

what range is isoclinal fold

Answer 26

< 5

Question 27

what is the range of gently inclined

Answer 27

10 - 30

Question 28

what range is recumbent incline

Answer 28

< 10

Question 29

what range is moderately inclined

Answer 29

30 - 60

Question 30

what range is steeply inclined

Answer 30

60 - 80

Question 31

what range is upright incline

Answer 31

80 +

Question 32

hinge line at 90 means

Answer 32

vertical

Question 33

hinge line at 80

Answer 33

steeply plunging

Question 34

hinge line at 20

Answer 34

gently plunging

Question 35

what is the order of describing a fold

Answer 35

plunge and trending direction
inclination
tightness of fold