Ocean Lab 3 Beach Sand Composition

1 OCEAN LAB 3 BEACH SAND COMPOSITION

Assignment 1: test and identify the basic composition of beach sand from various Hawaiian islands.  black sand  green sand  white sand  red sand  coral/shell sand  magnetic sand

Background Information

Ocean Geologic Features: Sediment

Marine Rocks & Sediments – Review Sedimentary Rocks Sedimentary rocks form through the precipitation of minerals directly from water (example: salt flats that form when seawater evaporates) or through the lithification of sediment – small particles of rocks, minerals, and organic material, broken up, transported, and deposited in piles. Two lithification processes are: • Cementation of sediments usually by aqueous solutions that percolate through sediments and deposit calcite, quartz, or iron oxide glues that then cement the sediments together). Example: sandstones that used to be sand dunes. • Compaction of sediments (usually by being buried under progressively more and more layers of other rocks and sediments). Example: Mudstone or shale that used to be layers of ooze. Grain size is important for sedimentary rocks. We use grain size (if grains are present) to help determine the formation environment and rock type:  Gravel (>2 mm) – Associated with high-energy waters, like headlands or the base of cliffs.  Sand (< 2 mm, > 1/16 mm) – Associated with moderate-energy waters, like beaches or rivers.  Mud (<1/16 mm) – Associated with low-energy waters, like lagoons and the deep sea.

Igneous rocks form from the solidification of magmas (molten rock). Magmas form at depth when the Earth’s mantle melts. Hot, fluid magmas are lower density than the rocks within which they form. Magmas rise toward Earth’s surface, where they cool to become igneous rocks. If magmas erupt on the Earth’s surface, they cool very quickly and form crystals that are too small to see with the eye or no crystals at all (glass). We call such igneous rocks extrusive or volcanic. If magmas cool slowly under the surface, they can form large crystals. We call such igneous rocks intrusive or plutonic. All igneous rocks are either volcanic or plutonic. Igneous rocks that you can find in oceanic settings are primarily basalt and abbro: high-density, dark colored rocks. Basalt is the extrusive form; gabbro the intrusive form. These rocks form when magma supply is large and consistent and doesn’t have to travel through thick crust (remember: 2 oceanic crust is very thin – 5 km). Such settings include spreading centers, ocean-ocean subduction zones, and oceanic hotspots. Wherever basalt erupts, underneath the surface some of that same magma is trapped and cools slowly to form the intrusive equivalent of basalt, called gabbro. Continental igneous rocks, on the other hand, are primarily granites – lower density than basalt, and light colored. Granites form when magmas have a long transit time through the crust – that’s why they’re associated with continents, whose crust is very thick – up to 100 km in some places. Remember: basalts are denser than granites. This difference leads to oceanic crust being much more dense than continental crust, which is why oceanic crust (thin and dense) subducts, while continental crust (thick and buoyant) doesn’t. 3

Rock name Description Possible formation environment Basalt Black, microcrystalline, Oceanic volcanoes – dense. Can show spreading centers, island weathering (rust) on arcs associated with exposed surfaces. subduction zone volcanism, and hotspots. The pillow basalt variety forms when oceanic volcanism occurs under water, chilling the lava quickly as it erupts from cracks or vents on the seafloor.

Gabbro Macrocrystalline. Underneath oceanic Minerals visible with volcanoes (where basalts eye – olivine (green), form at the surface). pyroxene (black), and Forms when basaltic plagioclase (grey). magmas cool slowly under the surface.

Granite Macrocrystalline. Underneath continental Minerals visible with eye volcanoes where long- – quartz (clear to grey), travelled magmas cool feldspar (white or pink), slowly under the surface. and biotite or hornblende (black).

Diagnostic key: Are the crystals all big enough to see? (all surface reflect light well?) No – Basalt (should be black); Yes – Gabbro OR Granite. Is the rock mostly light colored? No – Gabbro (dark colored) Yes – Granite (light colored) 4 Metamorphic rocks Metamorphic rocks form from the alteration of other igneous or sedimentary rocks. Such alteration occurs from increases in pressure, increases in temperature, and/or addition of chemically active fluids. . Rock name Description Possible formation environment Serpentinite Green (any shade), Mantle rocks that are mottled, exposed to hydrothermal massive. Smooth, solutions rounded under seafloor spreading slippery surfaces. Usually centers. Minerals in rocks displays slickened hydrate to form low grooves density serpentine, on outside surfaces eventually pockets of which squeeze upward along subduction zones towards the surface (like watermelon seeds squeezed between your fingers).

Beach Materials Lab Exercises COMPOSITION IDENTIFICATION GUIDELINES Samples are available for reference. These hints will help with composition ID:  Magnetite – Place a bit of sample onto white paper and hold over a magnet.  Granite – Note that the rock granite is composed of the minerals feldspar, quartz, and a nonmagnetic, dark mineral. The rock will look salt-and- pepper colored.  Quartz – Clear and glassy. Typically jagged because it is such a hard mineral.  Feldspar – Typically white or pink and tablet shaped. Opaque. Distinguishing from shells can be difficult. Look to see if other shells are present for comparison.  Shells – Typically white or blue. Can come in any shape or size, though usually has pits, ridges, ornamentation, or is thin and curved.  Serpentinite/Chert – Typically smooth, rounded red or green (various shades) and homogenous in color. 5 GRAIN SIZE IDENTIFICATION GUIDELINES Most of the sand you will looking at is sand sized. Expect it to range from large muds to fine gravels. Use scales provided in prereading to compare against sample, but also be sure to check your answers by comparing samples against each other. Line them up from finest to coarsest and make sure your answers match!

PERCENTAGE IDENTIFICATION GUIDELINES Percentages are estimates. Expect there to be differences from one person to another. What shouldn’t be different, however, is relative abundance. First thing you should do is ask which size or composition is the most abundant, then next, etc. Make sure your numeric percentages match that relative analysis and add to 100%. Example: Q>>F>Sh>>>>>C means that Quartz is much more abundant than Feldspar, which is more abundant than shells, all of which are WAY MORE abundant than Chert/Serpentinite.

TRAVEL DISTANCE DETERMINATION GUIDELINES To determine distance traveled, just use grain sizes and composition. Shape and sorting are not useful indicators for beaches, because wave activity on the beach rounds and sorts most grains!

SOURCE DETERMINATION GUIDELINES Go back to the composition data to answer this question. Ensure your numbers there match your numbers here. First off, your shell percentage should match your reef percentage (reefs are where shelled organisms live). Reefs are right offshore of the beach and represent little transit. Secondly, all low-resistance components must be locally derived; any transport would have broken them down. Usually, the medium-resistance components are also locally derived, though it is possible for some of them to have been transported a distance. Use other information to make this determination. The resistant components can either have traveled a long distance OR have been locally derived. Use grain size and local rock types to make this decision. For example, a beach of mostly fine-grained quartz has had all the low-to-medium resistance components removed. Grain size and composition indicate long-distance travel. However, a beach with high amounts of quartz, but also feldspar and black nonmagnetics components (likely hornblende) could originate from the breakdown of a local granite, if one exists. Grain size in such a case should be larger than the former case.

SAND-USE GUIDELINES Stir sand in jars thoroughly. Make sure Petri dish is clean (no sand grain contamination). Take only a pinch of sand out of NEW jar. When done with sand, if you’re sure which disposal jar to put it in, put in the OLD jar. (If you’re not sure ask!) Clean Petri dish thoroughly. You do not want contamination. 6 7

HAWAII – BIG ISLAND – SAND DATA ANALYSIS Composition (estimate percentages of Grain size (estimate percentages of each) each) Note: components in () are difficult to distinguish among in field. Relative abundance: Relative abundance: Most resistant components: Quartz (Q) Gravel (G) (>2 mm) ____% ____% Coarse sand (CS) ____% Medium resistant components: Medium sand (MS) ____% Magnetite (M)____% Fine sand (FS) ____% Feldspar (F)____ % Mud (<1/16 mm) (M)____% Least resistant components: Granite (G) ____% (Hornblende/Basalt/Mudstone: dark & nonmagnetic) (B) ____% (Chert/ Serpentinite) (C) ____% Shells (Sh) ____% Using the above data as evidence, does this sand appear to have been transported a great distance? Cite evidence.

Using the above data as evidence, indicate source of this beach sand. Local rocks are young basalt lava flows.

Local sources % Longshore Local reef % Other (describe transport % below): %

DETAILED EXPLANATION OF OTHER CATEGORY IF NECESSARY: 8

MAUI – RED SAND BEACH– SAND DATA ANALYSIS Composition (estimate percentages of Grain size (estimate percentages of each) each) Note: components in () are difficult to distinguish among in field. Relative abundance: Relative abundance: Most resistant components: Quartz (Q) Gravel (G) (>2 mm) ____% ____% Coarse sand (CS) ____% Medium resistant components: Medium sand (MS) ____% Magnetite (M)____% Fine sand (FS) ____% Feldspar (F)____ % Mud (<1/16 mm) (M)____% Least resistant components: Granite (G) ____% (Hornblende/Basalt/Mudstone: dark & nonmagnetic) (B) ____% (Chert/ Serpentinite) (C) ____% Shells (Sh) ____% Using the above data as evidence, does this sand appear to have been transported a great distance? Cite evidence.

DETAILED EXPLANATION OF OTHER CATEGORY IF NECESSARY: 9

HAWAII – OAHU: KAILUA – SAND DATA ANALYSIS Composition (estimate percentages of Grain size (estimate percentages of each) each) Note: components in () are difficult to distinguish among in field. Relative abundance: Relative abundance: Most resistant components: Quartz (Q) Gravel (G) (>2 mm) ____% ____% Coarse sand (CS) ____% Medium resistant components: Medium sand (MS) ____% Magnetite (M)____% Fine sand (FS) ____% Feldspar (F)____ % Mud (<1/16 mm) (M)____% Least resistant components: Granite (G) ____% (Hornblende/Basalt/Mudstone: dark & nonmagnetic) (B) ____% (Chert/ Serpentinite) (C) ____% Shells (Sh) ____% Using the above data as evidence, does this sand appear to have been transported a great distance? Cite evidence.

DETAILED EXPLANATION OF OTHER CATEGORY IF NECESSARY: 10 http://www.gly.uga.edu/railsback/sands/sandshawaii.html

4 3 7 1 8

11 SAMPLE 1: Ke'e Beach, Kaui

Brown mixed carbonate-siliciclastic beach sand collected from Ke'e Beach on northwest Kauai, Hawaii. 12 SAMPLE 2: Lihue, Kaui

. Light brown, orange colored carbonate sand collected from near Lihue on the southeast side of Kauai, Hawaii 13 SAMPLE 3: Waimea Beach, Oahu

Orange colored carbonate sand from Waimea Beach on the north shore of Oahu, Hawaii. 14 SAMPLE 4: Waimea Beach and Sunset Beach, Oahu

Well rounded and highly polished brown carbonate sand from between Waimea Beach and Sunset Beach on the north shore of Oahu, Hawaii. 15 SAMPLE 5: Honolulu, Oahu

Light brownish carbonate sand collected from Honolulu, Hawaii. 16 SAMPLE 6: Waikiki, Oahu

Light brown carbonate sand from Waikiki Beach, Oahu, Hawaii. 17 SAMPLE 7: Waianapanapa State Park, Maui

The Hawaiian Islands consist almost entirely of basalt, and so black sands consisting of basalt fragments are common there. This sample comes from Waianapanapa State Park near Hana on Maui. The grains are strikingly well rounded, which is typical of a coarse sand in which grains are abraded on the sea floor. The white grains are fragments of mollusk shells. 18 SAMPLE 8: Waianapanapa State Park, Maui

This sample comes from Waianapanapa State Park near Hana on Maui. The sands nearby are black because they're derived from basalt like that throughout the Hawaiian Islands. This sample has undergone weathering and oxidation that have turned the color much more red. The original basalt appears to have been vessicular; you can see the tiny holes in the microscopic image below. 19 SAMPLE 9: Honokowai to Hahaina, Maui

A white and orange carbonate sand from between Honokowai and Hahaina on the western coast of Maui, Hawaii. 20 SAMPLE 10: Big Island

Black sand from the big island of Hawaii 21 SAMPLE 11: Mahana Bay, Big Island

This green sand is from Green Sand Beach in Mahana Bay on the southern coast of the Big Island of Hawaii. 22 Marine Rocks and Sediments

Organisms Shell material (CaCO3 Heterotroph or or SiO2) Autotroph 1. Diatoms 2. Radiolaria 3. Foraminifera 4. Which rock does reef material turn into?

5. List all sedimentary rocks composed primarily of CaCO3.

6. List all sedimentary rocks composed primarily of SiO2.

7. What is the primary difference between mudstone, sandstone, and conglomerates?

8. Complete this table, based on preceding tables: Rock name Original formation setting explanation of formation process Pillow basalt (pahoehoe) A’a Serpentinite Chert Sandstone 23 Calcareous Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm (0.0025 in) with individual grains too small to be distinguished without a microscope.(Wikipedia)

Calcareous mudstone in warm, shallow environments is derived from:

1) breakdown of calcareous algae 2) inorganic precipitation from seawater 3) disintegration of larger skeletal particles

Mudstones generally accumulate in low-energy environments

Sandstone is a sedmientary rock composed mainly of sand-size mineral or rock grains. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Rock formations that are primarily sandstone usually allowpercolation of water and are porous enough to store large quantities, making them valuable aquifers. Fine-grained aquifers, such as sandstones, are more apt to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestones or other rocks fractured by seismic activity. A conglomerate is a rock consisting of individual stones that have become cemented together. 24

White Sand Beach 25 Composition of Beach Sand in Hawaii:  Coral  Mollusc shells  Sponge spicules  Calcareous algal plates (Halimeda)  Coraline algae  Volcanic particles  Shark teeth

Kailua Beach Sand: The median grain diameter of surface sands is finest on the beach face (<0.3 mm) and increases offshore along the channel axis. biogenic carbonate (> 90%) skeletal fragments of coralline algae (e.g. Porolithon, up to 50%) calcareous green alga Halimeda (up to 32%), coral fragments (1-24%), mollusc fragments (6-21%) benthic foraminifera (1-10%)

Carbonate sources: (1) Framework builders  Accretion and bioerosion of coral-algal reefs o Coraline (red ) algae in Hawaii . Encrusting (2 kg/m2/yr) . Branching (up to 20 kg/m2/yr) o Corals in Hawaii . Porites, Montipora, Pocillopora Growth rates (1-10 mm/yr) Accretion rates (1-6 mm/yr) Gross production (3-7 kg/m2/yr) . Haunama Bay (-7 kg/m2/yr) . Coral-algae reef Kaneohe (2.6 kg/m2/yr) (2) Direct production  Calcification: o Halimeda (2-5 kg/m2/yr) o benthic foraminifera (0.9 kg/m2/yr) o mollusks and echinoderms (?) 26

Figure 9. Benthic foraminifera with agglutinated limu o Pele (foram ~ 2 mm across). Image © MBARI 2003. From: (http://www.volcano.si.edu/reports/bulletin/contents.cfm? issue=3108&display=complete)

Benthic foraminifera (www-paoc.mit.edu/paoc/research/abrupt.asp) 27

Halimeda (oceanexplorer.noaa.gov/.../media/halimeda.html)

Coraline Crustose Algae 28

The Life Cycle of a Black Sand Beach:

Black sand beaches are made of basaltic rock which comes from the lava flowing into the water and solidifying. Waves from the ocean crash onto the shores and erode the basaltic rock, grinding them into coarse sand grains which create these black sand beaches. Black sand beaches have a short life span as a result of new lava flow covering the black sand, and the weathering process is started all over again.

Interesting Fact about Black Sand:

It used to be a myth that where there was black sand, there was gold. Black sand indicates that the area is rich in minerals, including gold. The myth has been disproven because it does not happen most of the time. However, there is still a large correlation between the two- where one is found, the other is likely to be found as well. Coincidental? It is still unknown, but it has led quite a few people on wild goose chases!

What Black Sand is Comprised of:

 Iron rich mafic minerals  Basalt  Gabbro  Magnetite  Silica  Traces of metal such as: o Thorium

o Titanium o Tungsten o Zirconium  Traces of gemstones such as: o Garnet o Topaz o Ruby o Sapphire o Diamond 29 Locations of Black Sand Beaches:

Generally black sand beaches can be found in regions that have constant lava flow combined with high wave energy. They are found at the edges of volcanoes where there is an abundant source of mafic rock and a scarcity of silica.

Black Sand Beach

Big Island

http://lurbano- 5.memphis.edu/Classes/index.php/Green,_Black,_Red,_and_Pink_Sand_Beach es 30

The Life Cycle of a Red Sand Beach (Maui):

Red sand beaches are very rare. Because they are so rare, isolated, and difficult to get to, not much is known about them. It is known that the sand forms primarily from eroded volcanic cinder cones. Cinder is a pyroclastic igneous rock that is very similar to pumice. The cinder cones, which are very vibrantly red, erode into beautiful red sand beaches.

What Red Sand is Comprised of:

 Mostly Iron (and Hematite)  Mafic minerals  Basalt rock

Locations of Red Sand Beaches:

Red sand beaches also must be near a volcano, specifically ones that have cinder cones. They typically exist in bays or inlets where the waves cannot erode the sand away. They actually are still growing because of the repetitious deposition of the cinder and the minimal erosion of the sand. 31 The Life Cycle of a Green Sand Beach

Green sand beaches are extremely rare and are formed by basaltic igneous volcanic rock which has plentiful amounts of olivine. These rocks made of olivine can be one of two types: either a rock entirely made of olivine called a dunite rock, or a gem-like rock called a peridot. The rocks weather over time creating small particles of olivine, silica, and other basalitic particles. The olivine weathers quickly into sand crystals because it is formed at high temperatures and is unstable at the Earth's surface. The other basaltic rocks also gradually weather into sand. The olivine crystals are much heavier than the other sand crystals so they remain on the beach when the other sand is washed away due to the strong waves. Because olivine is scarce in comparison to the other rocks that come from lava flow, green sand beaches are rare and typically relatively small, ranging from 50 to 100 feet in length. 32

Interesting Facts about the green sand of Hawaii:

The Hawaiians considered green sand to be the tears of the Goddess Pele and used the sand in healing ceremonies. Peridot is also the August birthstone and is used in jewelry as well as collected as a gemstone.

What Green Sand is Comprised of:

 Olivine  Silicates  Iron  Magnesium

Green Sand Beach Big Island

Mahana Bay, HI 33 References

Anderson, Genny. (2003). Hawaii Geology, Plate Tectonics/Hot Spot. Retrieved June 28, 2007, from Marine Science. Website:http://www.biosbcc.net/ocean/marinesci/02ocean/hwgeo.htm

Fitzhugh, Rod. (2002). Black Sand. Retrieved June 28, 2007, from Arizona Gold Prospectors. Website:http://arizonagoldprospectors.com/blacksand.htm

Forbes, Keith A. (2007). Bermuda's Beaches. Retrieved June 28, 2007, from Bermuda Online. Website:http://www.bermuda-online.org/beaches.htm

Microbus. (2007). Sand Anaylsis. Retrieved June 27, 2007. Website:http://www.microscope-microscope.org/applications/sand/microscopic- sand.htm

The Basalt Beach. Retrieved June 27, 2007. Website:http://www.albion.edu/geology/Geo210_Hawaii/MaunaLoa/Black %20Sand%20Beach.htm

U.S. Geological Society. (2004). Black Sand. Retrieved June 27, 2007, from Coastal Geology of the Parks. Website:http://geology.wr.usgs.gov/parks/coast/sand/blacksand.html

U.S. Geological Society. (2004). Green Sand. Retrieved June 27, 2007, from Coastal Geology of the Parks. Website:http://geology.wr.usgs.gov/parks/coast/sand/blacksand.html

Retrieved from "http://lurbano-5.memphis.edu:16080/Classes/index.php/Green %2C_Black%2C_Red%2C_and_Pink_Sand_Beaches" 34 Oceanography Lab 3: Sediment

Assignment 2: Visit any Oahu beach and evaluate the sand. Fill in the following worksheet and make sure you answer all of the questions. It is O.K. to visit a beach with a lab colleague, but you will need to submit your own evaluation sheet in your own words.

Beach Visited:______

Date: ______

Time: ______

Tide: __ High __Low __ Spring __Neap

Describe the size, texture, and composition of a handful of sand.

Texture:

Composition:

What factors do you think are involved with creating this beaches sand?

Do you think the time of day would affect your sand sample? Explain your reason.