olatiles in the Earth-Moon system, A chlorine isotope perspective

Lead Research Organisation: Open University
Department Name: Physical Sciences

Abstract

Recent work focussing on hydrogen isotope systematics of lunar samples have indicated a common origin for water in the Earth-Moon system (e.g., Tartèse and Anand, 2013; Saal et al., 2013). On the other hand, chlorine isotope composition of lunar samples have been used to argue for an anhydrous Moon (Sharp et al., 2010) in apparent contradiction to the growing database of measured water contents in a variety of lunar rocks requiring a significantly wetter lunar interior (e.g., Tartèse et al., 2013). Much of the H isotope work in lunar samples have been carried out on apatite or volcanic glasses. In contrast, most of the chlorine isotope work has focussed on bulk-rock measurements with a very few analysis on apatites. Interestingly, except for lunar samples, Cl isotopic composition of pristine planetary materials measured to date, including terrestrial samples, display a very restricted variation (average d37Cl = -0.3 0.3). This characteristics has been used to argue for a homogeneous Cl isotope reservoir in the inner solar nebula (e.g., Sharp et al., 2013).
Lunar samples display more than 20 fold variation in their Cl isotopic composition (d37Cl ranging from -0.7 to 24 ), a characteristics considered to be a result of Cl isotope fractionation in absence of H (or water) and claimed to be consistent with sample measurements; a hypothesis currently becoming untenable in light of latest data. It is therefore imperative to evaluate other processes and scenarios that might give rise to extreme Cl isotopic fractionation as seen in lunar samples. Currently, there is a debate regarding some of the analytical protocols employed in bulk-sample Cl isotope measurements and hence the reliability of the bulk-rock data. Thus, it is desirable to apply a different technique for Cl isotope measurements which could provide an independent method to assess Cl isotope systematics of planetary samples.
Apatite and magmatic glasses are the major Cl-bearing phases in almost all planetary sples and are therefore suitable target for in-situ Cl isotope measurements by ion-probe techniques. The proposed project will build upon recent protocols developed at the Open University for measuring H and Cl isotopic composition in apatites and glasses using a NanoSIMS. The work will involve Cl isotope measurements in apatites and glasses in a range of lunar, terrestrial and other meteoritic materials to build a database with which to evaluate the processes and sources involved in imparting a specific Cl isotope composition in each case and help in developing a better understanding of the origin of volatiles in the Earth-Moon system.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/N50421X/1 01/10/2015 30/09/2020
1810163 Studentship ST/N50421X/1 01/10/2016 30/09/2019 Samantha Faircloth
 
Description Moon Night 2018 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Explore the work of the Apollo missions through audio and video clips.
Handle Moon rocks and meteorites, and explore the OU's Virtual Microscope collection of Apollo Moon rocks.
Learn how 3D printing could be used to build habitats on the Moon.
Journey to the Moon in an inflatable planetarium.
Walk on the Moon via an immersive virtual reality experience.
Leave your footprint on the Moon just as Neil Armstrong did and take a selfie on the Moon for a keepsake*.
Imagine living on the Moon - drawing competition.
Year(s) Of Engagement Activity 2018
URL http://www.open.ac.uk/science/physical-science/news/moon-night
 
Description Moon Night: Celebrate the 45th Anniversary of Apollo 17 (outreach event at the Open University) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact About 200 visitors - school students, their parents, siblings, and members of the general public, visited the OU to explore what it means to become an astronaut - and what the Apollo astronauts achieved on the Moon. Many exhibits at different stalls were being run, e.g. virtual microscopes, real meteorites to touch etc.
Year(s) Of Engagement Activity 2017
URL http://www.open.ac.uk/science/physical-science/news/moon-night-celebrate-the-45th-anniversary-apollo...
 
Description Primary school visit (Buckingham) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Active volcano and lava demonstration. Hands on rock demonstration.

Encompassed 'Natural disasters' with the main objectives being to describe key aspects of:

• physical geography, including: volcanoes and earthquakes and the water cycle.

As scientists:
States of Matter:

• Compare and group materials together, according to whether they are solids, liquids or gases.

• Observe that some materials change state when they are heated or cooled, and measure the temperature at which this happens in degrees Celsius (°C), building on their teaching in mathematics.

• Identify the part played by evaporation and condensation in the water cycle and associate the rate of evaporation with temperature
Year(s) Of Engagement Activity 2017
 
Description Primary school visit (Milton Keynes) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Active volcano and lava demonstration. Hands on rock demonstration.

Encompassed 'Natural disasters' with the main objectives being to describe key aspects of:

• physical geography, including: volcanoes and earthquakes and the water cycle.

As scientists:
States of Matter:

• Compare and group materials together, according to whether they are solids, liquids or gases.

• Observe that some materials change state when they are heated or cooled, and measure the temperature at which this happens in degrees Celsius (°C), building on their teaching in mathematics.

• Identify the part played by evaporation and condensation in the water cycle and associate the rate of evaporation with temperature
Year(s) Of Engagement Activity 2018