Abstract Details
(2020) The Secret Life of Impact Breccias: Chondritic Phosphate Shock Textures
Walton C, Williams H & Shorttle O
https://doi.org/10.46427/gold2020.2706
01a: Room 1, Tuesday 23rd June 06:57 - 07:00
Craig Walton
Helen Williams View all 8 abstracts at Goldschmidt2020 View abstracts at 5 conferences in series
Oliver Shorttle View all 7 abstracts at Goldschmidt2020 View abstracts at 12 conferences in series
Helen Williams View all 8 abstracts at Goldschmidt2020 View abstracts at 5 conferences in series
Oliver Shorttle View all 7 abstracts at Goldschmidt2020 View abstracts at 12 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 Liszewska Katarzyna on Monday 22nd June 23:32
Thank you for an interesting presentation. I would like to ask you two questions. 1) Phosphates in your samples are very small. In this case, which method do you consider as the most reliable to obtain resolvable U-Pb ages? 2) Do you expect to measure the U-Pb ages that reflect process other than shock metamorphism? How would you differ them from the ages that represent shock stage?
Hi Liszewska! Thanks for the question. The phosphates themselves vary from < 10 micrometres to > 100s of micrometres. However, the microstructures within them are typically small, indeed. This really stresses the point that dating methods with a high spatial resolution are needed when working with such samples - I am currently working with several people to compare a few options, but I expect that SIMS is likely to have the best results. SIMS has been used on meteoritic phosphates in the past, of course, but rarely with the microstructures in mind! Regarding non-shock ages, we may struggle to resolve ancient ages that are older than the end of thermal metamorphism. However, ancient ages in low shock stage meteorites are likely to reflect end of radiogenic heating.
Thank you for an interesting presentation. I would like to ask you two questions. 1) Phosphates in your samples are very small. In this case, which method do you consider as the most reliable to obtain resolvable U-Pb ages? 2) Do you expect to measure the U-Pb ages that reflect process other than shock metamorphism? How would you differ them from the ages that represent shock stage?
Hi Liszewska! Thanks for the question. The phosphates themselves vary from < 10 micrometres to > 100s of micrometres. However, the microstructures within them are typically small, indeed. This really stresses the point that dating methods with a high spatial resolution are needed when working with such samples - I am currently working with several people to compare a few options, but I expect that SIMS is likely to have the best results. SIMS has been used on meteoritic phosphates in the past, of course, but rarely with the microstructures in mind! Regarding non-shock ages, we may struggle to resolve ancient ages that are older than the end of thermal metamorphism. However, ancient ages in low shock stage meteorites are likely to reflect end of radiogenic heating.
Submitted by Xin Yang on Tuesday 23rd June 04:58
Thank you so much for this great talk. Is there any age difference between these phosphates with different microstructures? Or it is possible that meteoroids experienced multiple impacts and phosphates formed in several periods? Thank you.
Hi there! Right now, it does appear that the phosphates with high shock stages (and hence different microstructures) have young U-Pb ages, overall. There is also some evidence for multi-stage shock in the U-Pb ages of the heterogeneous phosphates, but as of yet nobody has actually connected the ages to the textures. I have some samples awaiting analysis at the Stockholm NordSIM facility, which will begin to answer the question of which age corresponds to which textural feature (and hence impact).
Thank you so much for this great talk. Is there any age difference between these phosphates with different microstructures? Or it is possible that meteoroids experienced multiple impacts and phosphates formed in several periods? Thank you.
Hi there! Right now, it does appear that the phosphates with high shock stages (and hence different microstructures) have young U-Pb ages, overall. There is also some evidence for multi-stage shock in the U-Pb ages of the heterogeneous phosphates, but as of yet nobody has actually connected the ages to the textures. I have some samples awaiting analysis at the Stockholm NordSIM facility, which will begin to answer the question of which age corresponds to which textural feature (and hence impact).
Submitted by Xin Yang on Tuesday 23rd June 04:59
Thank you so much for this great talk. Is there any age difference between these phosphates with distinct microstructures? Or it is possible that meteoroids experienced multiple impacts and phosphates formed in several periods? Thank you.
Thank you so much for this great talk. Is there any age difference between these phosphates with distinct microstructures? Or it is possible that meteoroids experienced multiple impacts and phosphates formed in several periods? Thank you.
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