EXPLORING MARINE SEDIMENTS USING GOOGLE EARTH

EXPLORING MARINE SEDIMENTS USING GOOGLE EARTH Kristen St. John, James Madison University stjohnke@jmu.edu Part 1. Stories from the Sea Floor – A Lesson on How Science Works Time est. 15-30 min. 1. Watch the 10 min video on How Science Works https://www.youtube.com/watch?v=JH0_xC7q9tU p roduced by the Consortium for Ocean Leadership. It explores the process of how real science works using an example from an expedition to sea of the International Ocean Discovery Program. On this expedition the geoscientists study cores of marine sediment to reconstruct what climate was like in the past. 2. Answer the following questions on your own and then discuss with classmates : a. Is the scientific method linear? According to the video, a scientific method is not a linear one. This is caused by a process of knowledge and different questions. Usually in a process of gathering data, making hypotheses, and finding the answers. b. List three things you learned from this video about the PROCESS of science: They do not have any sequence of activities. It does not include any conclusion. Many stages and knowledge are involved in it. c.In describing how science works, the video focuses on a team of international scientists who are studying past climate by examining marine sediments. List one thing you learned about past climate from this video: The team examined different shades of clay. They concluded that the presence of absence of ice indicates the colors of the clay and may tell about the Earth's history Imprinted on the rocks. Part 2. A First Look at Marine Sediments Time est. 1 hour Introduction The sedimentary layers of the seafloor contain amazing stories about past ocean conditions, climates (e.g., see video in Part 1), and environmental changes. The first step in learning how to read those stories is to get familiar with the different sediment types of the seafloor. The purpose of Part 2 of this exercise is make observations about the different types of sediment deposited in the modern ocean. You will visit five locations in the Pacific Ocean where the scientific research vessel, the JOIDES Resolution ( http://joidesresolution.org/ ), drilled into the seafloor and recovered long cylinders of sediment. You will read about the sediment, “pull-up” cores of sediment, and view an image of the same sediment as seen under a microscope. This will give you multiple views of the seafloor: from the global scale of Google Earth, down to a 7-cm diameter core, and at the microscopic level. Comparing and contrasting your observations will help you distinguish one sediment type from another, which can lead to hypotheses about how these sediment types form. Procedure 1. Go to the project instructions in the course content area and click on First Look_v4.kmz . Save the file to your computer, and then click on the file to open it. This will automatically open the file in Google Earth. It will be located (along with all of its subfolders) under Temporary Places as shown here. 2. Click on Read Me First , and adjust the settings in Google Earth to optimize visualizations of bathymetric features, and read the tips and notes. Close the Read Me First pop-up page by clicking the “X” in the upper right. 3. Click on First Look at Marine Sediments and read the introduction (or skip if you already read the introduction above). 4. Visit each of five site locations by double clicking on the name of that location (e.g., ODP 181-1122A). For each location be sure to do the following: Record your observations about water depth, geography (e.g., distance from land, bathymetric features), sediment color, texture (grain size), and composition, and your answers to site-specific questions in Table 1. Below are some tips for accomplishing this task: a. Read and view the site (placemarker) information by opening the place folder (e.g., ODP 181-1122A), and double clicking on the “ starred ” site name (e.g., ODP 181-1122A). This contains background information, links, and questions to consider as you view the sediment core images. For example you can view photos of the sediment that were taken through a binocular microscope. To access these images click on the links embedded in the site information. When you open an image, notice the scale bar in the lower right hand corner of the image. Depending on the image, the scale bar is 0.05 to 1 mm in length. For comparison, sand- sized grains are between 0.06 and 2 mm diameter, silt-sized grains are between 0.004 and 0.06 mm diameter, and clay-sized grains are < 0.004 mm. b. "Pull up" a section of core from

the seafloor to see what the sediments looks like in the upper few meters of the ocean floor. To do this, double click on the label “Elevate Core” next to the Google Earth icon (see yellow arrow in screenshot) ; this brings you closer to the site of interest. Then double click on the “Elevate Core” next to the Video Camera icon (see red arrow in screenshot) ; this will actually elevate the core up from the seafloor. You can repeat or pause the core elevation by using the pop-up controller in the bottom left of the screen. NOTE: Do NOT unclick the subfolder with the 3-D box symbol labelled Core. c. Record the Water Depth: look at bottom right corner of screen. Water depth is reported as negative elevation (depth below sea level). d. Record the Distance from Land : use ruler icon. But note that ruler icon won’t work when elevate core is active. e. Describe the Sea Floor Bathymetry : use descriptive words like flat basin, seamount, underwater plateau, continental shelf, etc. f. Describe the Sediment : describe what the sediment looks like (color, texture) and what it is composed of based on the information you read about each site, the photos at the microscopic level, and the elevated core images.GEODE: Marine Sediment (K. St. John) Table 1. First Look at Marine Sediments - Summary Observations Site Locations ODP 181-1122A ODP 145-887C ODP 199-1215B ODP 202-1236A ODP 178- 1100C Water Depth (m) -14684 -10348 -17590 -8651 Distance from Land (km) 711.37 km 256.96 519.80 km 942.83 km 954.57 km Seafloor Bathymetric Features Sediment Description At .1 mm the sediment looks like shattered glass. At .1 mm the sediment looks like it is fossilized. At .1 mm the sediment looks like sand on a beach. Site Specific Questions Do you think this sediment is mostly land derived or biologically derived? Combinationof both What factors do you think might make the surface waters here an excellent setting for bio-siliceous primary productivity? the availability of nutrients like silica, favorable light conditions, sufficient mixing of nutrient-rich deep waters, and the presence of diatoms or other silica- utilizing organisms. Why do you think the sediment is so fine grained and uniform in composition? I would say because it’s a little bit closer to an island. This calcareous-rich sediment is among the most common sediment type on ridges, and seamounts, and plateaus. It is not found in the deep basins even if the surface waters were rich in calcareous phytoplankton. How might this be explained? The absence of calcareous- rich sediment in deep basins despite rich surface waters in calcareous phytoplankton could be explained by factors like dissolution of calcium carbonate in the water column during transport to the deeper regions, dilution of calcareous material by other sediment components, or selective preservation of non-calcareous materials in the deep basins due to specific chemical or environmental conditions. How might we get a mix of fine and very coarse sediment on the seafloor? Pelagic sediments either terrigenous or biogenic, are those that are deposited very slowly in the open ocean either by settling through the volume of oceanic water or by precipitation. The two most common types of sediment on the ocean floor are lithogenous sediments, deri ved from rocks, and biogenous sediments, which are derived from living organisms . The two most common types of sediment on the ocean floor are lithogenous sediments, derived from rocks, and biogenous sediments, which are derived from living organisms . Based on the composition of the sediment and the seafloor bathymetric features nearby, where do you think the sediment originated? I would say that a lot of it originated in the Earth, it could have brought itself up over time. Based on the composition of the finer materials, and knowing that there are also large pebbles in the cores, what process(es) do you think might have been involved in transporting the sediment to this seafloor location?

A “check” should appear in the box next to that folder name you want to focus on first. Be sure that all of the other sediment typos are unchecked, and if the First Look folder from Part 2 is still open then uncheck it as well. 3. Rotate the globe to explore the geographic and bathymetric distribution of each sediment type. This will be easier if you first examine each sediment type separately . Water depth (i.e., negative elevation) can be estimated by looking in the bottom right corner of the Google Earth page, or can be specifically determined by double clicking on the site name or symbol, which will bring up a site-specific information table, along with links to a wide range of site data and scientific reports. Record your observations in Table 3. 4. Propose hypotheses to explain the distribution patterns you see. In other words, try to address WHY the sediment types are where they are in the global ocean? Also consider what additional information you would want to obtain to test your hypotheses. Record your ideas in Table 3. 5. Select an IODP, ODP, or DSDP core location and find out more about why that location was targeted for coring, and what the key results were from the research conducted on material recovered from that core. For example, you might want to select one of the sites that the geoscientists in the video from Part 1 were studying. These were sites in the North Atlantic Ocean off of Newfoundland Canada: Sites U1402 to U1411. To address these questions click on the information table for the core and then explore the publications links. The Scientific Prospectus will tell you about the scientific questions the wanted to address by coring the sea floor in that region. The Preliminary Report or the Initial Report will tell you about the first results from the drilling expedition, and provides detailed descriptions of the cores and the sediment compositions. The Proceeding Report or Scientific Report will provide access to results from longer term research studies, as well as a synthesis of the scientific team’s findings. Record your finding below: · What site did you select? The ODP core location selected is ODP, Site 625. · Where is it located? The ODP core location is located in the North-Eastern Gulf of Mexico region. · Why was this location targeted for coring? This location is targeted for coring purposes since a significant quantity of natural gas and hydrocarbon was detected in this region. · What are two of the scientific results from research on cores from this site? ● There is a considerable amount of clay in the sediment depth. ● There is a substantial reservoir of hydrocarbon beneath the test site. GEODE: Marine Sediment (K. St. John) Table 3. Observations and Hypotheses on the Distribution of Surficial Sea Floor Sediment Types. Marine Lithologic Name and symbol color used in Google Earth Data Map. Note open circles are mixed sediment types, but still dominated by that primary lithology. Observations About Distribution Your Hypotheses to Explain the Lithologic Distribution Other Information You Would Want In Order to Test Your Hypotheses Terrigenous It occurs near the land. Areas with this deposit are near the land. It occurs near the land, because they are carried to the ocean by rivers from the ground. Samples from rivers so that it can be test the hypothesis. Glaciomarine It occurs near the North and South Pole areas. Sediments are carried to the ocean by glaciers and ice. Samples from sediments of glacier lakes and rivers for testing the hypothesis. Calcareous Ooze Occupies most areas far from the land. Accumulates faster than other sediments in the open oceans far from land. Samples from pelagic are needed to test the hypothesis.

Siliceous Ooze It occurs in small amounts in open ocean. Formed slower then other pelagic sediments. More pelagic sediment samples needed to test the hypothesis. Red Clay It occurs mostly in the pacific ocean. It is in the pacific ocean because the allogenic component originates from areas surrounding the Pacific ocean. Red clay sediment is needed to test the hypothesis. Part 4. Refining Your Hypotheses on Biogenic Sediment Distributions Time est. 1.5 hours Introduction Marine sediments are largely either land-derived or biologically derived. However, the two biologically derived sediment lithologies (i.e., the calcareous and siliceous oozes) have different sea floor distribution patterns. The purpose of Part 4 of this exercise is for you to refine your hypotheses on the distribution pattern of calcareous and siliceous oozes based on the addition of sea surface temperature and chlorophyll data and an explanation of the carbonate compensation depth (CCD). Procedure 1. Go to the project instructions in the course content area and click on: Surficial Sea Floor Sediment Map Data v4.kmz. Save the file to your computer, and then click on the file to open it. This will automatically open the file in Google Earth. Display only the Calcareous Ooze and Siliceous Ooze data, by “unchecking” all of the other marine sediment folders. It is also good to unclick the Sediment Legend as another data set will be added in a moment and their labels overlap. 2. Go to the project instructions in the course content area and click on: World and Regional Sea Surface Temperature.kmz . Save the file to your computer, and then click on the file to open it. This should automatically open the file in Google Earth. Click on the open circle next to the file name ( green arrow in screenshot) to make the layer visible. This file displays NASA satellite derived ocean surface temperature data. Click on the Adjust Opacity box ( pink arrows in screenshot) so that the transparency “slide bar” is visible ( blue arrow in screenshot). Slide the bar so that you can see both the sea surface temperature data and the sites of calcareous and siliceous ooze. Answer the questions below that compare SST and biogenic sediment distribution: · What pattern do you see in sea surface temperatures (SST)? There is not a pattern. The sea surface temp ranges from 30F-80F or More. The middle of the Earth has the warmest sea surface temp. The North and South Poles have the coldest. · How does the distribution of calcareous ooze compare with the pattern of SST? Describe both the general similarities and any exceptions. The distribution of calcareous ooze compares with the pattern of sea surface temperature because, in polar regions it is more likely to be a siliceous-based ooze. · How does the distribution of siliceous ooze compare with the pattern of SST? Describe both the general similarities and any exceptions. The distribution of siliceous ooze is also influenced by other factors such as nutrient availability, water depth, and the presence of sediment-consuming organisms. In general, the distribution of siliceous ooze and sea surface temperature patterns are correlated, but there are exceptions where the distribution of siliceous ooze does not match the pattern of SST. · How might surface ocean temperature play a role in the distribution of calcareous and/or siliceous oozes on the sea floor? Surface ocean temperature plays a role in the distribution of calcareous and/ or siliceous oozes on the sea floor because depth, temperature, and pressure can affect the ability of calcium carbonate to dissolve. 3. Go to the project instructions in the course content area and click on: Chlorophyll.kmz . Save the file to your computer, and then click on the file to open it. This will automatically open the file in Google Earth. Click on the open circle next to the chlorophyll file name (and unclick the temperature layer) to make this chlorophyll layer visible. It displays NASA satellite derived chlorophyll data for the global ocean. The unit is milligrams per cubic centimeter. The chlorophyll content is a measure of primary biological productivity (the product of

depth of the sites and the carbonate concentrations. Answer the question below on finding the CCD: · What is the sea floor feature that this transect of sites crosses? A Oceanic Trench · At what depth would you place the CCD in the North Atlantic Ocean? Explain your reasoning. North Atlantic ocean CCD · What do you predict the sediment type to be along this transect where the percent of CaCO 3 is high? Silicious ozone because of the deep waters What do you predict the sediment type to be along this transect where there is 0% CaCO 3 ? Terrigenous, because of the shallow waters Turn the Surficial Sea Floor Sediment Map Data v4 back on (i.e., check the box next to the file name) to check your predictions. · How does ocean chemistry serve as one control on the distribution of calcareous oozes? Ocean chemistry serves as one control on the distribution of calcareous ooze because of the way it mixes and sits with the water. Calcareous ooze gives life to ocean animals and supplies oxygen and nutrients for them. · Do you predict the CCD to rise or fall with atmospheric global warming? Explain your reasoning. I predict that CCD will increase as the atmosphere warms. With global warming, sea temperatures rise and more Shells dissolve below a certain depth which will make the ocean water more acidic by generating more CO2 and when the amount of carbon dioxide is very high, the depth of the CCD becomes shallow. Therefore, ocean acidification will increase CCD depth. Take boiling water for example. If you boil it too much, the water will dissolve. This is the same concept as ocean heating. This is my prediction. Because I believe that CCD increases due to man-made and natural climate change.