Tag: meteorite

Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returns

Backscatter electron microscope images of a meteorite

This paper is available as an Open Access article via the journal.

This research paper continues the work of Paula Lindgren, who I worked with earlier when looking at a suite of meteorites. In this paper, a single carbonaceous chondrite meteorite was heated in the laboratory to simulate the heating that took place during the life of a meteorite. A sample was studied using a series of different techniques, including scanning electron microscopy, Raman spectroscopy, infra-red spectroscopy, oxygen isotopic analysis and X-ray diffraction. It was then heated to 400 °C and 800 °C and studied again. We found that the minerals, isotopes and organic matter all changed with heating. Sometimes 400 °C was enough to make a change, sometimes no change was observed until 800 °C.

Changing Raman spectropscopy measurements from unheated (blue), 400 °C (yellow) and 800 °C (red) samples of the same meteorite

These changes can be used to work out the thermal history of meteorites collected on Earth, and even for asteroids sampled in space!

Elephant Moraine 96029, a very mildly aqueously altered and heated CM carbonaceous chondrite

This paper is a result of collaboration with researchers at the University of Glasgow who I met while interviewing for a position. I didn’t get the job, but I did get talking to Paula Lindgren and we discovered a common interest in using Raman Spectroscopy to study organic carbon. This publication is the first result of that, and is available as an open-access article.

A little bit of meteorite, under an electron microscope
A little bit of meteorite, under an electron microscope

The paper is a comprehensive study of a meteorite collected from Antarctica. Antarctica is a great place to find meteorites because they sit on top of the ice and are easy to spot – sometimes the flow of ice even concentrates them into particular areas to makes things even easier. This meteorite is classified as a “CM carbonaceous chondrite” and has experienced very little change since it was part of the protoplanetary disc billions of years ago. Therefore we can use it like a time capsule to look at what the early solar system was like.

However, some meteorites are better time capsules than others. As they float around the solar system, they can build up ice, which can then be melted by radioactivity and the water released can alter the crystallography of the meteorite. Our paper uses a wide range of techniques to characterise the meteorite and show that it is one of the least altered carbonaceous chondrites ever found.

The techniques used included electron microscopy (both scanning and transmission techniques; SEM and TEM), X-ray analysis, X-ray diffraction, thermogravimetric analysis (TGA), oxygen isotope measurements and Raman Spectroscopy. My contribution was to use my automatic Raman processing technique to determine how crystallised the carbon in this meteorite was in comparison to carbon in other meteorites.