Abstract Details
(2020) Hydrogen Isotopic Analysis of CM2 Chondrite Murchison
Chapman B & Bose M
https://doi.org/10.46427/gold2020.361
The author has not provided any additional details.
01a: Room 1, Monday 22nd June 22:42 - 22:45
Brendan Chapman
Maitrayee Bose View all 3 abstracts at Goldschmidt2020 View abstracts at 7 conferences in series
Maitrayee Bose View all 3 abstracts at Goldschmidt2020 View abstracts at 7 conferences in series
Listed below are questions that have been submitted by the community that the author will try and cover in their presentation. To submit a question, ensure you are signed in to the website. Authors or session conveners approve questions before they are displayed here.
Submitted by Evelyn Füri on Monday 22nd June 13:00
(How) Did you assess possible matrix effects for D/H analyses of different mineral phases? Were the H count rates (i.e., 'water' contents) of the different targeted phases comparable?
Previous analysis by our research group (Jin and Bose 2019 Science Advances, please see supplementary figure S5) under similar analytical conditions indicate that SMOW normalized D/H ratios do not vary in different silicate minerals (or matrices), and the differences in their compositions are small compared to the analytical errors. While this left us confident that any trends observed in our data are linked to variations in sample chemistry, we know that matrix effects and matrix matched standards will be of paramount importance in our future work. We are planning on building a larger dataset on different silicate minerals and glass standards, which will help constrain and correct for matrix effects in future analysis of CM carbonaceous chondrites. In answer to your second question, the use of only one standard (PMR53, a NIST clinopyroxene hydrogen isotope standard) precluded the creation of a calibration curve for water concentration.
(How) Did you assess possible matrix effects for D/H analyses of different mineral phases? Were the H count rates (i.e., 'water' contents) of the different targeted phases comparable?
Previous analysis by our research group (Jin and Bose 2019 Science Advances, please see supplementary figure S5) under similar analytical conditions indicate that SMOW normalized D/H ratios do not vary in different silicate minerals (or matrices), and the differences in their compositions are small compared to the analytical errors. While this left us confident that any trends observed in our data are linked to variations in sample chemistry, we know that matrix effects and matrix matched standards will be of paramount importance in our future work. We are planning on building a larger dataset on different silicate minerals and glass standards, which will help constrain and correct for matrix effects in future analysis of CM carbonaceous chondrites. In answer to your second question, the use of only one standard (PMR53, a NIST clinopyroxene hydrogen isotope standard) precluded the creation of a calibration curve for water concentration.
Submitted by Evelyn Füri on Monday 22nd June 13:00
(How) Did you assess possible matrix effects for D/H analyses of different mineral phases? Were the H count rates (i.e., 'water' contents) of the different targeted phases comparable?
(How) Did you assess possible matrix effects for D/H analyses of different mineral phases? Were the H count rates (i.e., 'water' contents) of the different targeted phases comparable?
Submitted by Larry Nittler on Monday 22nd June 19:04
nice presentation. What H2O contents did you measure for the grains?
The use of only one standard (PMR53, a NIST clinopyroxene hydrogen isotope standard) precluded the creation of a calibration curve for water concentration in this measurement session.
nice presentation. What H2O contents did you measure for the grains?
The use of only one standard (PMR53, a NIST clinopyroxene hydrogen isotope standard) precluded the creation of a calibration curve for water concentration in this measurement session.
Submitted by Kaitlyn McCain on Monday 22nd June 21:45
When polishing the thick section of hydrous and anhydrous phases on the lapping films, what steps can be taken to avoid plucking of anhydrous grains from the matrix?
The dry-polishing technique that we have found to be most effective was developed by my colleague Dr. Timothy Hahn. He demonstrated that a back and forth linear motion in the same location without lifting the sample from the polishing surface for 1-2 minutes between checks at an optical microscope allows a small amount of debris to collect beneath the sample being polished and act as a lubricant. My initial inclination had been to always provide a clean surface for every stroke, taking care to pick up the sample at the end of every stroke and move it to a new location, stopping the stroke and blowing away any dislodged silicate debris as soon as I felt it abrade the sample. I paired this with several different stroke patterns and holding regimes but this method was always inferior at preventing both plucking and the subsequent scarring caused by the dislodged silicates.
When polishing the thick section of hydrous and anhydrous phases on the lapping films, what steps can be taken to avoid plucking of anhydrous grains from the matrix?
The dry-polishing technique that we have found to be most effective was developed by my colleague Dr. Timothy Hahn. He demonstrated that a back and forth linear motion in the same location without lifting the sample from the polishing surface for 1-2 minutes between checks at an optical microscope allows a small amount of debris to collect beneath the sample being polished and act as a lubricant. My initial inclination had been to always provide a clean surface for every stroke, taking care to pick up the sample at the end of every stroke and move it to a new location, stopping the stroke and blowing away any dislodged silicate debris as soon as I felt it abrade the sample. I paired this with several different stroke patterns and holding regimes but this method was always inferior at preventing both plucking and the subsequent scarring caused by the dislodged silicates.
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