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GEOL 404: EXAM 1
A regression occurs when?
A) sea level is falling
B) sea level is rising
C) sea level rises faster than the land is uplifted
D) none of the above
|
A) sea level is falling |
A transgression occurs when?
A) sea level is falling
B) sea level is rising
C) sea level rises faster than the land is uplifted
D) none of the above |
B) sea level is rising |
Define "Structural Cross Section" and "Stratigraphic Cross-Section" |
* Structural Cross Section reveals the true positions and true vertical depth of rock layers and deformation structures
*Stratigraphic cross section shows depositional variations of rock layers without deformation structures and without revealing the true depth |
Type of map: Depth contours of a subsurface formation
A) Structural Contour map
B) isopach map
C) isochore map |
A) Structural contour map
|
Type of map: shows contours of true stratigraphic thickness of a formation
A) Structural Contour map
B) isopach map
C) isochore map |
B) Isopach Map
|
Type of map: Contours of true vertical thickness of a formation
A) Structural Contour map
B) isopach map
C) isochore map |
C) isochore map |
What is the environment that corresponds to "ALLUVIAL" deposition? |
Continental |
What is the environment that corresponds to "FLUVIAL" deposition? |
Continental |
What is the environment that corresponds to "DELTA" deposition? |
Transitional |
What is the environment that corresponds to "LAGOON AND REEF" deposition? |
Marine |
Turbidites are deposited in?
A) Alluvial Environment
B) Fluvial Environment
C) Beach Environment
D) Shallow water carbonate platform
E) Deep marine fan |
E) Deep marine fan
|
What is the environment that corresponds to "REEF" deposition? |
High wave energy |
What is the environment that corresponds to "PLATFORM SLOPE" deposition? |
Low wave energy
|
What is the environment that corresponds to "LAGOON" deposition? |
Medium wave energy |
The closer to a hydrocarbon reservoir, the salinity of the connate water tends.....
A) to be higher
B) to be less
C) to remain the same |
A) to be higher
|
Gas is said to be "sweet" or "sour", based on the absence or presence of?
A) H2S
B) CO2
C) N2 |
A) H2S |
What are the major effects of subsidence due to basin fills on sediments?
A) Porosity reduction
B) Permeability Reduction
C) Pressure increase
D) Temperature increase
E) All of the above |
E) All of the above |
Which of the following sequences will most likely result in a petroleum accumulation? from beginning to end
A) source rock, deposition of reservoir, formation of structural trap, maturation and migration, overburden rock
B) source rock, reservoir, seal, overburden rock, structural trap, maturation and migration |
B) source rock, reservoir, seal, overburden rock, structural trap, maturation and migration |
Earth's lithosphere is broken into large plates. the 3 major kinds of plate boundaries are... |
Divergent Margin, Convergent margin, and transform margin
|
MC: What is the major cause for the movement of tectonic plates?
A)Rapid convection in liquid outer core
B) slow convection in solid mantle over geologic time
C) Earthquakes
D) Volcanoes |
B) slow convection in solid mantle over geologic time |
Which of Earth's layers corresponds to "AUGITE (PYROXENE) AND OLIVINE WITH NO FELDSPAR" composition?
A) Core
B) Mantle
C) Oceanic crust
D) continental crust |
B) Mantle |
Which of Earth's layers corresponds to "HIGH SiO2, K2O, AND Na2O" composition?
A) Core
B) Mantle
C) Oceanic crust
D) continental crust |
D) continental crust |
Which of Earth's layers corresponds to "BASALT AND GABBRO" composition?
A) Core
B) Mantle
C) Oceanic crust
D) continental crust |
C) Oceanic crust |
Which of Earth's layers corresponds to "Fe AND Ni metal" composition?
A) Core
B) Mantle
C) Oceanic crust
D) continental crust |
A) Core |
Which rock corresponds to the mineral "CLAY"?
A) Shale
B) Sandstone
C) limestone
D) Dolostone
E) Granite
F) Basalt |
A) Shale |
Which rock corresponds to the mineral "QUARTZ"?
A) Shale
B) Sandstone
C) limestone
D) Dolostone
E) Granite
F) Basalt |
B) Sandstone |
Which rock corresponds to the mineral "CALCITE"?
A) Shale
B) Sandstone
C) limestone
D) Dolostone
E) Granite
F) Basalt |
C) limestone |
Which rock corresponds to the mineral "DOLOMITE"?
A) Shale
B) Sandstone
C) limestone
D) Dolostone
E) Granite
F) Basalt |
D) Dolostone |
Which rock corresponds to the mineral "MICA, FELDSPARS"?
A) Shale
B) Sandstone
C) limestone
D) Dolostone
E) Granite
F) Basalt |
E) Granite |
A) Shale
B) Sandstone
C) limestone
D) Dolostone
E) Granite
F) Basalt |
F) Basalt |
Types of Faults? |
*strike-slip fault
*transform fault
*normal fault
*reverse fault
*etc |
Folds and reverse faults in a mountain belt suggest?
A) Compressional Stress
B) Volcanoes
C) Tensional stress
D) All of the above |
A) Compressional stress |
Which of the following minerals can be transported a long distance by water without being dissolved or broken down?
A)Orthoclase (K-spar)
B) Calcite
C) Quartz
D) plagioclase |
C) Quartz |
What is the correct order of grain size deposition when moving from "close to the source" to "far away from the source"? |
1. Pebbles
2. Very coarse sand
3. Coarse Sand
4. Medium sand
5. fine sand
6. very fine sand
7. silt
8. clay |
What region corresponds to "BOUNDSTONE, and GRAINSTONE" rocks?
A)reef
B) slope
C) lagoon |
A)reef |
What region corresponds to "PACKSTONE, WACKESTONE, and MUDSTONE" rocks?
A)reef
B) slope
C) lagoon |
B) slope |
What region corresponds to "PACKSTONE, and WACKESTONE" rocks?
A)reef
B) slope
C) lagoon |
C) lagoon |
List the 5 major steps of the wilson cycle in the order of their occurence. |
1) continental rift-New Young Basin
2) Passive margin boundaries-strike slip
3) Ocean closing- island arc formation
4) island arc- continent collision
5) Continent-continent collision |
What are Hydrocarbons? |
*Made of complex molecules of hydrogen and carbon
*Organic matter is chemically transformed into hydrocarbons |
Petroleum system: |
source rock, reservoir rock, seal, trap, maturation and migration |
What are the 4 levels of petroleum investigation? from level of assessment |
1)Sedimentary Basin
2) Petroleum system
3) Play
4) Prospect |
What is a gas hydrate? |
*12-sided cages (dodecahedrons) with gas molecules inside results in a stable crystalline structure at proper temperature and pressure
*A unit volume of methane Hydrate stores > 160 volumes of free gas equivalent at STP
*are crystalline water-based solids physically resembling ice, in which small non polar molecules (typically gases) are trapped inside "cages" of hydrogen bonded water molecules. In other words, clathrate hydrates are clathrate compounds in which the host molecule is water and the guest molecule is typically a gas. |
What is the cause of Earth's magnetic field? |
Rapid convection in the liquid outer core |
What causes plate movement? |
Slow convection in the solid mantle |
Types of Margins? |
1. Divergent
2. Convergent
3. Transform |
Explain Divergent Margin...
*Motion:
*Effect:
*Topography:
*Volcanic Activity?: |
*Motion: Spreading
*Effect: Constructive
*Topography: Ridge/Rift
*Volcanic Activity?: Yes |
Explain Convergent Margin...
*Motion:
*Effect:
*Topography:
*Volcanic Activity?: |
*Motion: Subduction
*Effect: Destructive
*Topography: Trench
*Volcanic Activity?: Yes
|
Explain Transform Margin...
*Motion:
*Effect:
*Topography:
*Volcanic Activity?: |
*Motion: Lateral sliding
*Effect: Conservative
*Topography: no major effect
*Volcanic Activity?: No |
Examples of a Convergent margin.... |
*Arabian Plate and Eurasion Plate Boundary
*Pacific Plate and Eurasian Plate
|
Examples of a Divergent margin.... |
*Arabian Plate and African Plate
*Eurasian Plate and North American Plate |
Examples of Transform margin... |
Scotia Plate |
Decompression Melting process... |
*hot rocks move into area of lower pressure without losing heat
*occurs in upper mantle below spreading centers (divergent plates)
*Occurs where mantle material rises to hot spots or plume
|
What crust?
*mafic
*denser, younger
*High thermal gradient
*Basalt/Gabbro/olivine |
Oceanic Crust
|
What crust?
*Felsic
*lighter, thicker, old
* low thermal gradient
*rhyolite/granite/quartz/mica
*K,Al,Ca,Na,SiO4 |
Continental Crust |
Continental Rifting |
*Break up o continental lithosphere (weaker than ocean crust)
*Breakups form graben (normal/listric faults)
*sediments deposit in graben |
Hydration |
*water added to lower melting temp of mantle
*occurs at sinking ocean crust |
Mineral Groups |
*Silicates (quartz, olivine, feldspar, clay)
*Carbonates (calcite, dolomite)
*Sulfates (gypsum)
*Halides (salt)
*Oxides |
Contact Metamorphism |
*increasing porosity
*Chlorite/ Amphibole/ epidote/ garnet/ pyroxen/ hornfels
|
Carbonate Rocks |
*limestone (calcite)
*dolostone (dolomite) |
Sedimentary Process |
1. Weathering/Erosion
2. Transport
3. deposition
4. lithification |
hydrolosis |
*dissolution of minerals carbonic acid
*hydrogen ions replace rock |
Stable minerals |
*Quartz
*Muscovite
*Clay |
Clastic Deposition (bedforms) |
*low velocity: ripples (small cross bedding)
*Medium velocity: dunes (large cross bedding)
*High velocity: planar bed (horizontal stratification) |
Carbonate Deposition |
*high wave energy: platform edge (reef) "boundstone, grainstone"
*medium wave energy: lagoon "wackestone, packstone"
*low wave energy: platform slope "wackestone, mustone" |
Biochemical Rock |
*Diatoms/radiolariums remove Si from water to make shells (chert) |
Transitional Deposition |
*Sabkha: stranded ocean
*strand: beach
*delta: river outlet
*littoral: |
Marine Deposition |
*sublittoral: shelf
*lagoon
*Buthynl: slope
* Abyssal: deep ocean
*Hadal: trenches |
Alluvial Fans |
*cone shaped body of sediment: stream enters valley, shape created by shifting channels
*coarse grains at top of fan |
Sabkha |
*tract of land with high evaporation
*occurs in hot climate between desert and shore
*Percipitates: gypsum, salt, halite, calcite |
Braided Stream |
*interlaced tangled streams
*common between alluvial fan and meandering stream
*occurs from river fluctuation/ erodible banks |
Meandering Stream |
*single confined stream (low gradient)
*particle size decreases downstream |
Delta Deposition |
*river enters large body of water
*high accumulation
*good sorting
*major petroleum reservoir in clastics |
Beach Deposition |
*clastic
*sand is deposited parallel to slightly inclined layers |
Deep Marine Deposition |
*Deep marine fans
*deposition of turbidites (graded beds) from density currents |
Stratographic Sequences (length) |
*continental rifting (>50 my)
*Plate movements (3-50 my)
*uplift, subsidence (.5-3 my)
climatic cyclic event (10,000-50,000 years) |
Regression |
*sea level retreats (deposition: sandstone on top, mudstone on bottom) |
Transgression |
*increase sea level (deposition: Mudstone on top, sandstone on bottom) |
Types of folds |
*Anticline: Petroleum tram (upwards dome shape)
*Syncline: (U shape)
*Monocline: minor fold |
Affect of (T, P) on deformation |
*15-20 km gives way to ductile
*few deep earthquakes/faults (too hot to break: except in subduction zone)
*water weakens rock: increase ductility |
Know Normal Fault |
*caused by tension
**PICTURE** |
Know Reverse Fault |
*caused by compression
**PICTURE** |
Know Thrust Fault |
*caused by compression (shortening of crust by .5-20-750 km)
**PICTURE** |
Listric Fault |
*fault plane becomes closer to horizontal with depth
*normal and thrust can be listric
**PICTURE** |
Strike Slip Fault |
*horizontal movement
**PICTURE** |
Deformations in Rocks |
*folds: bent structures (ductile deformation)
*Faults: brittle with offset
*Fractures: brittle with no offset (result from bending/stress/cooling volcanic rock |
Structural Cross Section |
*shows depth using sea level TVD
*Shows rock layer position and deformation
*used to show potential traps
|
Stratigraphic Cross-Section |
*hung along a reference surface (subsurface marker)
*shows layers as originally deposited and how they relate
*NO deformation!!!!! |
Net Sand Map |
*Contours sand: shale ratio of formation
*also called reservoir quality map |
Net Pay Maps |
*contours gross pay to net pay ratio
*gross pay: total vertical interval from top to bottom
*Net pay: cumulative thickness from where petroleum can be produced |