Download Homework 1c KEY

Geology 3263
Structural Geology
Homework 1
Name _____________________________________
Homework is not graded. It serves as a partial topic review for Quizzes and Tests.
Look in your books, the internet, confer with your classmates, etc.
THIS ONE IS JUST A CHECK. I want to get a feel for what each student was
taught in their Introduction to Geology course.
A. Mixed Format
1. In a breccia, the coarse particles are (choose: angular / rounded) .
2. A rounded grain of quartz greater than 0.0625 mm and less than 2mm would be
a (choose one: mud particle, grain of sand, pebble)
3. Salt, Gypsum and other chemical sediments that form when a body of water
dries up are called (choose: halogens / alluvium / evaporites)
5. In graded bedding, the coarsest grains settle to the bottom first, and grain size
decreases gradually toward the top of a layer.
6. Pyroclastic materials that cool and solidify from lava ejected into the atmosphere
are called tephra.
5. When basaltic lava erupts beneath the sea, it forms a pillow lava structure.
6. A volcano with a composite cone has layers of frozen lava OR basalt and
layers of pyroclastic material within the cone.
B. Match the terms
1. Gabbro _b___
a. intermediate silica content
2. Andesite __a___
b. coarse grain basaltic
3. Rhyolite ___c__
4. Fine-grained texture __d__
c. fine grain granitic
d. cooled rapidly
C. True or False.
1. The San Andreas Fault is an example of a transform boundary. True or False?
2. Water driven out of a subducting ocean plate causes partial melting in the
nearby mantle. The magma that may rise to form volcanoes. True or False?
3. The Himalayan Mountains are an example of a collisional boundary. True or
False?
4. When a solid is heated it contracts. True or False?
It expands
5. The Andes Mountains are an example of volcanic mountains that formed
above a subduction zone. True or False? A “continental volcanic arc”
6. Smaller plutonic features, such as dikes, generally appear in divergent (rifting)
zones. True or False? We see a lot of these, and sills, in the East African Rifts.
7. Oceanic rocks carried by subduction down into the aesthenosphere lose their
water, which flows out to surrounding mantle. The mantle can partially melt;
this process can generate vast quantities of magma. True or False?
8. Solid rocks that form deep in the Earth's interior may be raised to shallower
levels during a continental collision. True or False? Sure, the folding plus
erosion exposes, for example, the oldest rocks in the center of an anticline.
D. Multiple Choice. Select the best answer.
1) The Great Rift Valley of East Africa contains:
a. divergent plate boundaries
b. basalt rock from lava flows
c. stream and lake sediments
d. All of the above
2) The Triassic and Jurassic lowlands of New Jersey:
a. are the western margin of the rift that opened the Atlantic
b. contain the same rocks and fossils as similar rocks in Morocco
c. contain red shales with occasional dinosaur footprints
d. contain basalt rock formed from lava flows in a rift valley
e. All of the above
3) The Appalachians and other great mountain ranges contain:
a) Divergent plate boundaries
b) Convergent plate boundaries Repeated hits, the Grenvillian late PreC,
Taconic Ordovician, Acadian Devonian, Allegheny (impact of Africa in
Miss. Penn. and early Permian)
c) Transform plate boundaries
4) The San Andreas Fault contains:
a) Divergent plate boundaries
b) Convergent plate boundaries
c) Transform plate boundaries
5) The most abundant rock-forming minerals in the lithosphere are
a. Pyrite, Galena, Sphalerite, Halite, Gypsum, Anhydrite
b. Quartz, Feldspars, Micas, Amphiboles, Pyroxenes, Olivine Silicates, see
Bowen’s reaction Series, these form most rocks. The bulk of the remainder
are mudrocks made of clays, but clays are just weathered (hydrolyzed)
feldspars.
c. Wulfenite, Franklinite, Zincite, Andalucite, Pyrope
d. All of the above
6. The most important factor controlling igneous rock texture is
a. The composition of the parent magma
b. The rate of cooling of the magma
c. The amount of magma available
d. The amount of pressure on the magma
7. In divergent (MOR, rift) margins, the magmas that rise are typically
a. silica poor (basaltic a.k.a. mafic) Mid-ocean ridge rocks are basaltic. They
form when the aesthenosphere divergence cracks existing ocean lithosphere
above, letting in low pressure and water. The mantle partially melts,
yielding a hot, buoyant basaltic magma, which rises to fill the cracks and
makes new ocean lithosphere .
b. silica rich (granitic a.k.a. felsic)
c. intermediate in silica content
8. The term viscosity refers to:
(a) how heat and pressure influence volatiles.
(b) resistance to flow.
(c) how dense a solid is.
9. Which one of the following sedimentary sequences records regression?
a) shale overlain by quartz-rich sandstone with an eroded top In regression, it
is getting shallower in every body of ocean on earth. As it gets shallower, a
submerged area is closer to land and/or eventually dry and exposed to
weather. Regression sequences in a stack of sediment show a coarsening
upward, often with an eroded top.
b) Fine sand overlain by abyssal calcareous ooze.
c) Quartz-rich sandstone overlain by shale.
d) all of the above
9) Nappes are:
(a) non-marine foreland basin deposits accompanying the uplift of a
mountain belt.
(b) a large body of rocks that has been moved by thrust faulting, often with
recumbent folding Shown is a Nappe in the Alps.
(c) rhythmic alternation of deepwater muds and graded turbidite sands
formed between approaching continents
10) Flysch is:
(a) non-marine foreland basin deposits accompanying the uplift of a
mountain belt.
(b) a large body of rocks that has been moved by thrust faulting, often with
recumbent folding
(c) rhythmic alternation of deepwater muds and graded turbidite sands
formed between approaching continents. Often earthquake or storm
caused landslides dump continental shelf sands onto abyssal muds. The
sands are often graded.
11) Molasse is:
(a) non-marine foreland basin deposits accompanying the uplift
of a mountain belt. We saw this when we looked at the Catskill
Delta on the first field trip. The rocks went from black to green
to red as the water shallowed and iron became increasingly
oxidized.
(b) a large body of rocks that has been moved by thrust faulting,
often with recumbent folding
(c)rhythmic alternation of deepwater muds and graded turbidite
sands formed between approaching continents
The Catskill Delta
12) Fossil 1 is a:
(a) brachiopod
(b) crinoid
(c) rugose coral
(d) trilobite An arthropod loosely related to
modern groups, note the tree lobes from
side-to-side.
1
13) If you found fossil 1, you would be certain the
sediments containing it formed in the
(a) Cenozoic
1
(b) Mesozoic
(c) Paleozoic Trilobites appear in early Paleozoic rocks,
and survive until the end of the Permian, when 90% of
life died.
(d) Precambrian
14) Fossil 2 is a:
(a) brachiopod Brachiopods were most diverse in the
Paleozoic
(b) crinoid
(c) rugose coral
(d) trilobite
2
E. Mixed Format
1) On a topographic map, contours mark
lines of equal elevation. True or False?
2) This photograph, taken by Kean University student Andrew Stockum,
shows Mt. Vesuvius, near Pompeii and Herculaneum, and east of
Naples, Italy. It sits above a subduction zone. Its lavas and tephra are
most likely:
a) Basaltic
b) Andesitic
c) Rhyolitic
Copyright 2007 A. Stockum. Used with permission
Volcanoes above subduction zones often have intermediate silica, since they rise far enough to have
substantial fractionation
3) Next to pictures A, B and C, write a corresponding example. Choose from
Himalayas, Cascades, and Japan (You must get all three correct)
A. Andes, Cascades
B. Japan, Aleutians, Philippines
C. Himalayas, Alps, Appalachians in Paleozoic
4) These folds, visible in a hillside, are (choose one: overturned/recumbent)
5) These folds viewed from space are show plunging folds in the Appalachians. This very
severe folding was mostly due to the (choose: Taconic / Acadian / Allegheny ) Orogeny.
6) Above is a cross-section from a geologic map. Rocks marked O are
Ordovician, rocks marked Y are Precambrian.
Which came first (choose one: folding of Ordovician rocks/ a thrust
fault) Notice the thrust fault cuts through the folding Ordovician rocks
7) Below is a cross-section from a geologic map. Rocks marked lP are
Pennsylvanian, rocks marked P are Permian, rocks marked TR are
Triassic,
J Jurassic and K are Cretaceous.
Questions: a. Which came first (choose one: folding of Pennsylvanian
through Cretaceous rocks/ the fault)? The fault cuts the folds
b. This is a (choose one: Normal Fault/Reverse Fault/Transform Fault)
8) The cross-section below is from a geologic map. Rocks marked J are
Jurassic, K Cretaceous, and Q Quaternary.
Question: In the cross-section, the fault is younger than the Jurassic
rocks and the Cretaceous layer marked Kd. True or False?
9) There are 360 degrees in a circle, 60 minutes in a degree, and 60 seconds in a
minute.
10)
An arc of half a minute is equal to 30 seconds.
11) Which event is younger? (Circle one: the Sevier Orogeny or the Nevadan
Orogeny). We will talk about this after the test
12) The mid-ocean ridge separating the Farallon and Pacific plates was
subducted during the Cenozoic. True or False? We will talk about this after the
test
13) The mid-ocean ridges are made of rocks that are warmed by heat transferred
from the mantle below. This heating causes them to expand, and sea-level rises.
Question: During the Cretaceous, the Atlantic mid-ocean ridges were so large
that shallow seas covered the interior of North America. True or False?
Melted glaciers also cause sea-level rise.
14) Hot rising mantle rock loses its heat to the lithosphere above. It is forced
aside by hotter mantle rock rising from below. The mantle rock spreads out,
pulling the lithosphere apart. This causes the lithosphere to crack. The cracks
let in water and low pressure, and some mantle minerals melt, forming a new
magma body. The new material fills in the cracks in the lithosphere, forming
new ocean floor.
15) New ocean floor is made of granite. True or False? It is basaltic, see
Ophiolite
16) When mantle material under the lithosphere cools, it sinks back into the
earth's interior, pulling dense ocean lithosphere down with it, forming a
subduction zone. True or False?
17) Fact: New ocean floor lava is lumpy, with lots of spaces filled with wet
sediment between the lavas. In a subduction zone, water from sediment and
minerals is squeezed out at great depth, say about 150km. The nearby mantle is
exposed to water, and partially melts, despite the great pressure.
Question: These melts form new buoyant magmas that can rise to form huge
plutons (such as batholiths) deep underground and, if they reach the surface,
volcanoes. True or False?
18) During the Nevadan Orogeny, a volcanic arc formed on the west coast of
North America. All that remains are the deep batholiths under the arc: huge
blobs of magma that cool deep in the Earth.
Question: Batholiths are often made of granite. True or False?
19) When microplates rifted from Africa collided with southern Europe the
(choose: Alps / Himalayas / Appalachians) formed.
20) When India collided with Asia the (choose: Alps / Himalayas /
Appalachians) formed.