II. Question (25-50) Flashcards
Tension joints are parallel to the plane made by _____
a. σ₁ and σ₂
b. σ₂ and σ₃
c. σ₁ and σ₃
d. σ₁, σ₂, and σ₃
b. σ₂ and σ₃.
Explanation:
Tension joints form perpendicular to the direction of the least principal stress (σ₃) and are typically parallel to the plane formed by the intermediate (σ₂) and least (σ₃) principal stresses.
Back in figure 1 (Ocean Basins), what is on the number 2?
a. continental rise
c. subduction zone
b. volcanic arc
d. oceanic trench
d. oceanic trench
Shear joints are _______ to σ₂.
a. perpendicular b. parallel c. diagonal d. oblique e. nota
a. perpendicular
The true strike and dip of a limestone bed is N45°E and 30°NW respectively The apparent dip of the bed on a cross section trending N80°W is ______.
a. 15° b. 25° ‘ c. 35° d. 45° e. nota
a. 15°
Unloading joints are _____ to σ₁ .
a. diagonal b. parallel c. in same plane d. perpendicular e. nota
d. perpendicular
With respect to point A, the tunnel will cross the fault at _____ aerial meters to the north.
a. 50 b. 500 c. 5000 d. 5 e. nota
b. 500 aerial meters
The sense of movement most likely being suggested by the Riedel shears is:
a. left-lateral
b. right-lateral
c. oblique fault
d. dip-slip fault
e. cannot be determined
a. left-lateral
- What type of landform is on the figure?
a. volcanic caldera
b. volcanic crater
c. basin
d. dome - Which of the following type of drainage pattern predominates on the figure?
a. centripetal
b. radial
c. rectangular
d. both a and b
e. aota - What type of rocks probably is on the figure?
a. sedimentary
b. metamorphic
c. igneous
d. either of a, b, and c - Which of the following is probably deposited at the edges on the figure?
a. ash/bombs/blocks
b. tuff
c. lava flows
d. aota
- a. volcanic caldera - The image shows a large, circular depression that resembles a caldera, formed by the collapse of a volcano.
- a. centripetal - The drainage pattern appears to flow inward toward the center, typical of calderas.
- c. igneous - Caldera formations are typically associated with igneous rocks, especially volcanic products.
- a. ash/bombs/blocks - These materials are commonly found at the edges of volcanic features like calderas.
A vein that strikes N 45W and clips 35 NE is exposed on the southwest side of a mountain range. Its upper surface outcrops at an elevation of 1400 it while its lower surface outcrops at 1200 feet. The slope distance between the outcrops measured perpendicular to its strike is 500 feet.
a. Find the thickness of the vein.
b. Calculate the depth to the top of the bed at a point 600 feet of where it outcrops, this point is at an altitude of 1800 feet. On the same location, calculate the depth to the bottom and of the bed and determine vertical thickness.
Thickness of the vein: 287 ft
Depth to the top of the bed: 820 ft
Depth to the bottom of the bed: 1107 ft
Vertical thickness: 235 ft
What is the correct order of the deposition/ formation of the rock layers/ structures shown?
a. ABC
b. CBA
c. CAB
d. BAC
a. ABC
One limb of a fold strikes N35°W and dips 45°NE. The other limb strikes N10°E and dips 60°NW. The plunge (dip angle and direction) of the fold axis is _______.
a. 26° 86°E b. 6°S26°E c. 6° N26°W d. 26° N6°W e. nota
c. 6° N26°W
The type of fold most likely being depicted in the Figure above is a:
a. antiform
b. synform
c. recumbent fold
d. monocline
e. none of the above
b. synform
The sense of movement being shown above is:
a) Sinistral strike slip fault
b) Dextral strike slip fault
c) Normal fault
d) Thrust fault
e) A and B
b) Dextral strike slip fault
Mountains are likely to be associated with the feature above in
a. A
b. B
c. A and B
d. Neither A or B
b. B
Valleys and basins are likely to be associated with the feature above in (same choices as 95)
a. A b. B c. A and B d. Neither A or B
a. A
The displacement on this fault is
a) north-south,
b) east-west,
c) up-down,
d) over-under,
e) cannot determine without additional information.
b) east-west
This picture shows a fence offset by a fault. This is an example of
a) a normal fault,
b) a reverse fault,
c) a right-lateral strike slip fault,
d) a left-lateral strike slip fault,
e) my fault.
d) a left-lateral strike-slip fault
A vein strikes N90°E and dips 35 ° to the south. What is its apparent dip in a N 45°E section. In what direction would its apparent dip be at 75 °.
Apparent dip = 26°
Apparent dip direction = South
- What type of deposit is the model?
- Label all the alteration zoning.
- Put an asterisk on the chart where the mineralization is hosted with sedimentary-metamorphic intrusion related Au/Cu/Fe deposit.
- Put a check on the high sulfidation system.
- The model represents an epithermal Cu-Au porphyry deposit.
- The typical alteration zones in an epithermal Cu-Au porphyry system are:
Potassic Zone (K-silicate): Characterized by secondary biotite, K-feldspar, and magnetite. Usually found near the core.
Phyllic Zone (Quartz-Sericite-Pyrite or QSP): Dominated by sericite, quartz, and pyrite. It typically surrounds the potassic zone.
Argillic Zone: Composed of clay minerals like kaolinite, illite, and smectite. Forms on the outer parts of the system.
Propylitic Zone: Characterized by chlorite, epidote, and calcite. It forms the peripheral alteration.
Advanced Argillic Zone: Contains alunite, pyrophyllite, and dickite, often associated with high sulfidation. - Mineralization related to Au/Cu/Fe deposits is typically associated with skarn deposits and porphyry copper systems at the contact zones between intrusions and sedimentary rocks.
The asterisk would be placed at contact zones or skarn areas near intrusive bodies. - High sulfidation systems are commonly found in the advanced argillic zone, where minerals like alunite and pyrite dominate.
The check would be placed in the upper portions of the system, near the volcanic vents or breccia pipes.
Natural cavity beneath the surface of the earth
Cave
Topography formed by intensive dissolution of limestone bedrock
Limestone
Coarse angular rock fragments that collect at the base of a cliff
Talus
Movement of rock or debris along a concave plane
Slump
A permeable body of subsurface rock or sediment that conducts water
Aquifer
The surface of the zone of saturation
Water table
