B-Lab Report 056 Hawaii Combined - All Versions-2
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School
University of South Florida *
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Course
2000
Subject
Geology
Date
Apr 3, 2024
Type
Pages
8
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Report 5-1 Laboratory Number Five: The Geology of Hawaii Name: Partners: Activity 5.1, The Landscape of Hawaii (10 Minutes)
O
BJECTIVE
: To familiarize yourself with the geography and landscape of the Hawaiian island chain, and to learn about its age-progression.
This activity uses the large 1:500,000-scale State of Hawaii, Principal Islands Shaded Relief Map and the 1:500,000-scale State of Hawaii, Principal Islands Topographic Map. 1.
There are eight principal islands in the Hawaiian chain, which increase in age toward the northwest. List the eight islands in order of age. List the youngest first: (4 points, ☆
) 1 2 3 4 5 6 7 8 1.
There are five volcanoes on the Big Island of Hawaii: Hualālai, Kīlauea, Kohala, Mauna Kea, and Mauna Loa
. Make sure you can locate them on the map. Which two are the highest? (2 points, ☆
) High volcano #1: High volcano #2: 2.
Which volcano is the oldest? (1 point, ☆
) 3.
Which volcano is the youngest? (1 point, ☆
) 4.
Based on the shape of the landscape, how many extinct volcanoes do you think are found on Oahu? (1 point, ☆
) 5.
Which volcano has steeper sides, Mauna Loa or Mauna Kea? (1 point, ☆
) Activity 5.2, Minerals of Hawaii (13 Minutes)
O
BJECTIVE
: To learn how to identify the four common minerals of Hawaii in hand sample: olivine, pyroxene, plagioclase, and magnetite.
NOTE: This activity must be done first, before any other rock or mineral activities in the laboratory. Box 1 contains pure specimens of the four minerals that are common in Hawaii: olivine
,
pyroxene
,
plagioclase
,
and magnetite
. Note that almost all of the magnetite found on Hawaii is microscopic. 1.
Examine the specimens carefully, and fill in the following table which summarizes their physical properties. When you are done underline the property or properties that you think will be most useful in identifying each mineral in hand sample. (3 points each, all ☆
) 2.
What additional property of magnetite makes it very easy to identify? (HINT: this is sort of like, “What food do they serve a
t Pizza Hut?”) (1 gift point,
☆
) Minerals of Hawaii, Activity 5.2 Cleavage? Hardness? Luster? Color? H-A1: Olivine H-A2: Magnetite H-A3: Plagioclase H-A4: Pyroxene
Report 5-2 Activity 5.3, Aphanitic, Phaneritic, Porphyritic (5 Minutes)
O
BJECTIVES
: To learn how to recognize aphanitic, phaneritic, and porphyritic texture in igneous rocks. This activity contains five rocks that aren’t from Hawaii, but which demonstrate the meaning of the terms aphanitic, phaneritic, and porphyritic. For each rock, check the appropriate boxes in the following table. (1 point each, all ☆
) Pick one! Porphyritic Aphanitic Phaneritic HU-1 HU-2 HU-3 HU-4 HU-5 Activity 5.4, Hawaiian Rocks (15 Minutes)
O
BJECTIVES
: (a) To learn how to recognize the important Hawaiian minerals in rocks; (b) To learn how to recognize basalt; and (c) To learn how to recognize the important textural features of volcanic rocks: aphanitic, phaneritic, porphyritic, and vesicular. In this activity, you will identify the common rocks found on Hawaii, without the aid of a microscope. Since all of these rocks are aphanitic volcanic rocks, your only reliable clue to the rock type will be in the phenocrysts. NOTE: You must also have completed Activities 5.2 and 5.3 before doing this activity. 1.
For each of the following five rocks, identify any visible minerals and name the rock (2 points each, ☆
). NOTE: Do not just list the minerals that might be found in the rock; list only those minerals you can identify in the rock with your naked eye or with the aid of a hand lens. Visible Minerals Rock Name HAW-1 HAW-2 HAW-3 Visible Minerals Rock Name HAW-4 HAW-5 2.
For the same rocks, check all that apply to the texture
of the rock: (1 point each, ☆
) Pick one! Porphyritic Aphanitic Phaneritic HAW-1 HAW-2 HAW-3 HAW-4 HAW-5 Activity 5.5, Thin Section #1 (6 Minutes
)
O
BJECTIVES
: (a) To learn how to recognize olivine in thin section; (b) To learn how to infer crystallization order from the texture of volcanic rocks, especially in thin section. NOTE: Activities 5.3 and 5.4 must be done before this activity. This activity uses a thin section of Rock HAW-1, a clastic rock from Mauna Loa Volcano on the Big Island of Hawaii. There are both a hand sample and thin section for this rock. You have already identified the minerals visible in hand sample for this rock in Activity 5.4. 1.
What is the major phenocryst in this rock? (1 point, ☆
) 2.
Examine the phenocrysts both in plain-polarized and cross-polarized light. Do they cleave or fracture? (3 points, ☆
) 3.
What birefringent colors do the principal phenocrysts display (i.e., grays, vivid, or washed-out)? (2 points, ☆
)
Report 5-3 Activity 5.6, Thin Section #2
(7 Minutes)
O
BJECTIVES
: (a) To learn how to recognize plagioclase in thin section; (b) to learn how to infer crystallization order from the texture of volcanic rocks, especially in thin section. NOTE: Activities 5.3 and 5.4 must be done before this activity. This activity uses a thin section of Rock HAW-2, from Kilauea Volcano on the Big Island. There are both a hand sample (Activity 5.4) and thin-section for this rock. 1.
The most abundant phenocrysts in this rock display gray birefringent colors. What mineral is this? (3 points, ☆
) 2.
The most prominent feature of these minerals is the presence of abundant polysynthetic twinning
that can be clearly seen in cross-polarized light. This twinning causes the crystals to appear “striped”. Are individual stripes always black or white, or do they change colors when the stage is rotated? (2 points, ☆
) 3. The pale yellowish crystals in the groundmass are pyroxene
. What is the order of crystallization of minerals in this basalt? Defend your answer. (2 points, ☆☆☆
) Activity 5.7, Thin Section #3 (4Minutes)
O
BJECTIVES
: (a) To learn how to recognize pyroxene in thin section. NOTE: Activities 5.3 and 5.4 must be done before this activity. This activity uses a thin section of Rock HAW-3, collected from the north side of the volcano Haleakala on the island of Maui. HAW-3 contains pyroxene phenocrysts. Pyroxene looks
somewhat similar to olivine, but can be distinguished by a pale green or brown color in plain-polarized light
. Olivine is clear in plain-polarized light. Also, the presence of cleavage may sometimes cause the pyroxene to appear “fibrous” in thin section. What birefringent colors does pyroxene exhibit? (4 points, ☆☆
) EXTRA CREDIT: The groundmass of HAW-3 contains pyroxene, plagioclase, and glass. The plagioclase appears as clear needles in plain light, while the pyroxene displays higher birefringence. The glass is nearly opaque due to the presence of magnetite inclusions. Based on the texture of this rock, what was the order of crystallization? Make sure you include the magnetite. Defend your answer. (3 points, ☆☆☆
) Activity 5.8, Thin Section #4 (7 Minutes)
O
BJECTIVES
: To learn how to recognize volcanic glass in thin section. NOTE: Activities 5.3 and 5.4 must be done before this activity. This activity uses a thin section of Rock HAW-4, which comes from Kilauea Crater on the Big Island of Hawaii. It is a piece of a recent lava flow, probably erupted in the past 100 years. 1.
Notice the material that is green in plain-polarized light. Is this material opaque, isotropic, or anisotropic? (3 points, ☆
) 2.
What is this material? (2 points, ☆
) Activity 5.9, All Kinds of Beaches (12 Minutes)
O
BJECTIVES
: (a) To review the identification of the principal Hawaii minerals in hand sample and thin section; To review the sediment properties of sorting and roundness as applied to Hawaiian beach sediment.
NOTE: You must complete Activities 5.2-5.8 before you can start this activity.
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