Where is the carbonate on Mars?

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Nili Fossae Region imaged by CTX. Image Credit: ASU/Malin Space Science Systems

Provenance: Image Credit: ASU/Malin Space Science Systems
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In-Class Activity 2_Water World

Julia Kahmann-Robinson PhD and Marjorie Chan PhD, University of Utah Department of Geology & Geophysics

Purpose

Expose students to the carbon cycle on Earth and how carbonate rocks are created. Students will develop a line of evidence or explanation for the reasons why carbonate rocks are not abundant on Mars.

Preparation

1. Depending on your mode of delivery (in class versus perhaps a homework setting), load the Image File .ppt for the class and make sure you have an Internet connection to view the associated videos.
2. Find 3 specimens of carbonate rocks (micrite, coquina, grainstone/packstone, or chalk) or use Image File to show 3 specimens of carbonate rocks.
3. Have JMARS available to view carbonate minerals maps of Mars, as well as MOLA maps for geographic context (see Image file in Resources of module shell).

Engagement

Have students observe 3 different carbonate rocks and ask the following:

1. What are the similarities between these rocks? [color, skeletal grains, texture etc.]
2. Where might these rocks have been deposited and form? What is your evidence? [If students suggest marine, ask why it could not be terrestrial, lacustrine, or fluvial? Use leman terms if necessary for these environments]

Exploration

Forming carbonate rocks on Earth

Have students brainstorm how carbonate rocks are formed. Write their ideas on the board.

Watch the following NASA video entitled "Keeping up with Carbon": http://www.youtube.com/watch?v=FgEZpX3n5mo

1. How does the student's "formation" history compare/contrast with the video?
2. What elements of the video's content exist/do not exist on Mars?

Carbonate rocks on Mars

Bring up JMARS maps of carbonate rocks for students to view the extent (or lack thereof) of carbonate rocks.

• Where are the carbonate minerals most common?
• Discuss why carbonate minerals are not common on Mars.

Explanation

Carbonates – a class of sedimentary rocks composed primarily of carbonate minerals ranging from calcite to dolomite.

Elaboration

Consider the biosphere, lithosphere, and current atmospheric conditions of Mars at present.

1. What would students need to change about Mars today for Mars to be conducive to carbonate development?
2. Answers can be elaborately crazy, i.e. put petroleum-powered cars on Mars and create vast amounts of CO₂ emissions or if possible move Mars closer to the sun so that it isn't so cold....etc.

Evaluation

Present Figure 1 of Mars (for a full resolution image see the Image File for this module) and ask students the following questions:

In this hypothetical situation (although real imagery)

1. Where might you find carbonates? [Have students approach the board/screen and point to areas; along channels or within crater basins]
2. What is the basis for their decision? [any water environment might have the potential]