Planetary Chemistry

University of Cambridge | Oliver Shorttle

Lent: the Easter vacation

Map exercise: Complete the map from the 2018 practical paper (section 4).

Thin section description: Describe rock specimens and thin sections I5 and I6 (these can be found in wooden draws in the IA lab, located beneath the long bench adjacent to the doors).
Refer to the short guide I have written to help you.

Essay plans: Go over your notes and read around the subject a bit!
A structured way of doing this is by identifying the IA tripos questions that relate to the Michaelmas and Lent term of the course (which you can access through Moodle), and use these essay titles to construct detailed essay plans. Where you can’t think what you would say, head back to the notes and then onto relevant textbooks to find the information you need and to furnish your answers with more quantitative detail and, especially, real-world examples of the processes you are describing.

Plan these essays from the last few years of tripos and bring them to the first supervision. Focus on :

[2019 – climate] Using the concept of global energy balance, account for the global average temperature at the Last Glacial Maximum (LGM). How can you reconcile your account with the Milankovitch theory of the ice ages, given that global average insolation at the LGM was similar to the present day?

[2018 – paleobiology] Outline the major patterns in animal biodiversity during the Phanerozoic. To what extent are geological events responsible for these patterns?

[2016 – sedimentology] What are the main types of sedimentary delta, and what are the physical parameters that control delta morphology and internal structure? How do you recognize a deltaic sequence preserved in the geological record?

[2020 – geophysics/planetary science] Discuss the differentiation processes responsible for the large-scale structure of the Earth since its accretion. How will a planet’s mass and accretion age affect its differentiation history?

[2020 – igneous petrology] The vast majority of volcanic activity on Earth occurs at mid-ocean ridges. Explain why this is so. Why are almost all magmas that are erupted at ridges basaltic in composition, whereas magmas erupted elsewhere show a much wider compositional range?

[2021 – geophysics] It has been observed that seafloor depth in the ocean basins increases systematically with crustal age.
a) Explain the nature and origin of this relationship.
b) To what extent does this relationship hold for plates older than ~70 million years? Explain your answer.
c) Using specific examples, explain how mid-ocean ridge spreading rate (i) affects ocean basin bathymetry today; and (ii) may have caused eustatic sea level change in the past.

[2021 – mineralogy] By contrasting a pyroxene and a mica, explain how and why a) birefringence, b) cleavage, and c) colour in plane-polarized light are related to the orientation of the crystal in a thin section under a petrological microscope.

— Bring to the first supervision of Easter Term —

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