GEOL 1404 Lab 1 Assignment Spring 2024
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Lab 1 Worksheet Sedimentary Rocks and Depositional Environments (50 points; 50 possible answers)
Name: Ashton Holland
Date: January 27, 2024
PDFs AND HANDWRITTEN SCANS WILL NOT
BE GRADED. ANSWERS MUST BE TYPED IN. ONLY THINGS YOU NEED TO TAKE AN IMAGE OF MUST BE HANDWRITTEN
Use your lab book, lab PowerPoints, and your brain as needed to answer all questions in each of the 2 parts. Please explain everything in your own words.
Part 1 Sedimentary Rocks Chapter 3
1.
Explain the difference between a quartz arenite and a feldspathic arenite.
a.
Sandstone whose sand grains are comprised to have about 90% to 100% of quartz are classified as quartz arenite while sandstone with significant amount of feldspar are classified as feldspathic arenite.
2.
What is meant by sorting of clastic sediments?
a.
Sorting of clastic sediments describe the average number of grain size in a rock. An extremely well sorted rock is fairly extremely rare, but it can be very common with the shales, and some few sandstones along with it.
3.
Identify one well sorted clastic rock and one poorly sorted clastic rock.
a.
Shale
b.
Conglomerate
4.
Explain what is meant by provenance? a.
In Geology, provenance is the reconstruction or rebuilding of the sediment’s origin, where all rocks transition between the three rock types of the rock cycle. Rocks being exposed to the surface will sooner or later be broken down into sediments where provenance will take its place and rebuild it back up in the origin of sediment.
5.
How do the grains, sorting, and texture of a clastic rock tell us about provenance?
a.
With grain, if a rock contains quartz grains, it can tell us about provenance
by suggesting that the sediment originally originated from a quartz-rich source like a granite or quartzite. Sorting can tell us by sorting out the well-sorted rocks from the poorly-sorted rocks by having the well-sorted rocks by long-distance transport and poorly-sorted be a minimal transport. With texture, it can tell us by the arrangement and orientation of grains and can reveal the process that transported and deposited the sediment.
So with these 3 characteristics, it can help make inferences about the original provenance.
6.
Describe the difference between an arenite and a wacke.
a.
If a rock has 0 to 5% matrix in it, it is classified as a arenite and if a rock has 5 to 50% matrix in it, it is classified to be a wacke.
7.
What information do we get from the colors of some clastic rocks?
a.
Red: Presence of iron oxide, indicate terrestrial deposits
b.
Black: Presence of carbon, deposited in bodies of low oxygen water, and black pyrite bearing shales deep marine or stagnant shallow lagoon.
c.
Red, pink, tan, yellow: Indicate terrestrial deposits
d.
Green, gray: Iron bearing unoxidized and shallow marine
8.
From the lab book define each of the following:
a.
Skeletal remains: They are the whole or partial remains of carbonate-
secreting plants and animals.
b.
Intraclasts: They are fragments of weakly consolidated carbonate sediments that have been eroded from the seafloor or from tidal flats by waves, storms, or tidal currents.
c.
Ooids: Defined as coated grains with a nucleus and concentrically laminated calcareous cortex, that is unique to carbonate rocks.
d.
Peloids: Is a sand-sized, pellet-shaped grain of carbonate mud that generally lacks internal structure.
9.
Explain how ooids form?
a.
They are form on shallow, high-energy carbonate shelves, such as Joulter’s Cay in the Bahamas, where the ooids are alternatively buried on the shallow seafloor and then reintroduced to seawater by storm- or tide-
induced erosion.
10.Explain the difference between a packstone and a grainstone.
a.
Packstone is characterized by the complete or partial fillings of interparticle pore spaces by carbonate mud, while grainstone is where grain-supported rocks lack interstitial mud.
11.What is micrite?
a.
It is when the matrix of most limestones consists of mud-size (<4 microns) calcite crystals are form as simply carbonate mud.
12.In what order do the evaporites develop?
a.
Aragonite, Gypsum, and Halite
13.Extensive evaporite deposits of rock gypsum and rock salt are found in which ‘system’ in the United States?
a.
Permian System
14.Which two fossil types can form boundstone?
a.
Algae and encrusting organisms
15.Which of the following best describes the rock seen in this image? Boundstone, Rudstone, Grainstone, or Packstone. a.
b.
Grainstone
Part 2 Depositional Environments Chapter 4
General questions
1.
What sedimentary rocks do we find forming in a delta and barrier islands environment?
a.
Sandstone, siltstone gray shale, coal, and mud-clast conglomerate
2.
What color of rocks would be common to alluvial fans?
a.
Red color
3.
What organisms are common to tidal flats?
a.
Mollusks, Algae, and Stromatolites
4.
What organisms are common to meandering stream environments?
a.
Vertebrates (dinosaur and mammals), whole in floodplain shales, broken in channel ss.
5.
If you lived in the pelagic zone, where do you live?
a.
In a region of the ocean that is outside of the coastal area known as the open ocean
6.
In which environment would symmetrical ripples develop?
a.
Tidal Flats Use the diagrams in chapter 4, Table 4.1 on page 43, pages 48-58, and the information box at the bottom of each picture set, to answer the following questions. (
Caution
: images on backside of page from questions
) Refer back to chapter 3 as needed
.
Part A Figure 4.7 (page 48)
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1.
What is the dominant sedimentary rock type shown in figure 4.7?
a.
Conglomerate
2.
What does the red color suggest about the environment of deposition?
a.
Red indicates oxidation
3.
Rocks of the North Horn Formation were most likely deposited in which of the sedimentary environments listed in table 4.1. Explain your answer.
a.
Alluvial Fan
b.
Explain: Fluvial because of the amount of oxidation, the gravel filled channels, the color is also an indicator, the table mentioned a variable in grain size and the fluvial description contains conglomerate and sandstone.
Part B Figure 4.8 (page 50)
1.
What is the dominant sedimentary rock type shown in figure 4.8?
a.
Sandstone and Siltstone
2.
What economically important sedimentary rock occurs in this outrcrop?
a.
Coal
3.
Rocks of the Blackhawk were most likely deposited in which of the sedimentary environments listed in table 4.1? Explain your answer.
a.
Delta and Barrier Island
b.
Explain: Because it contains sandstone, siltstone, and coal, the fossils are an indicator as well because of the root molds and the trace fossils which would be the dinosaur footprints.
Part C Figure 4.9 (page 52)
1.
What two sedimentary rocks types predominate in this formation?
a.
Pebble conglomerate and sandstone
2.
Rocks of the Cedar Mountain formation were most likely deposited in which of the sedimentary environments listed in table 4.1? Explain.
a.
Meandering Stream
b.
Explain: Fluvial because the fossils are preserved whole in the shale and broken in sandstone. Color is also an indicator because green, red, maroon, and light grey were found.
3.
Thinking question: Why would dinosaur skeletons be found more complete in shale than in sandstone.
a.
Sandstone has had a rougher environment that the fossils over there would break apart easily more often than fossils found in shale which has more strength in it to keep the fossils from breaking and can be easily complete in building a dinosaur skeleton.
Part D Figure 4.10 (page 54)
1.
What is the dominant sedimentary rock type shown in figure 4.10?
a.
Shale
2.
What does the black color suggest about the environment of deposition?
a.
The black color indicates low oxygen.
3.
What additional information is provided by the types of fossils found in the Mancos Shale?
a.
The fossils belong to marine animals so it would most likely be a body of water.
4.
Rocks of the Mancos Shale were most likely deposited in which of the sedimentary environments listed in table 4.1? Explain your answer.
a.
Deep Marine
b.
Explain: The rocks and rock color are an indicator as well as the types of fossils.
Part E Figure 4.11 (page 56)
1.
How would you describe bedding within the Moenkopi Formation?
a.
Very thin with a few ripple marks and mud cracks
2.
What do the mudcracks (Fig. 4.11E) suggest about the depositional setting?
a.
There was a body of water and then the area dried out afterwards.
3.
Rocks of the Moenkopi Formation were most likely deposited in which of the sedimentary environments listed in table 4.1? Explain your answer.
a.
Tidal flat
b.
Explain: A main indicator was the presence of symmetrical ripples. Mud cracks and trace fossils. Also the presence of sandstone, shale, and siltstone.
Part F Figure 4.12 (page 58)
1.
What do the cross-bedding, presence of crinoids, and oolitic nature of the limestone indicate about the environment of deposition?
a.
Carbonate sand shoals because it had to be a wet environment for the ooids to grow and the buildup of limestone.