Abstract Details
(2020) Investigating Titanomagnetite Abundance in Rhyolite Pumice
McCartney K, Hammer J, Shea T, Giachetti T & Brachfeld S
https://doi.org/10.46427/gold2020.1753
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05i: Plenary Hall, Thursday 25th June 06:45 - 06:48
Kelly McCartney
View all 2 abstracts at Goldschmidt2020
View abstracts at 2 conferences in series
Julia Hammer View all 5 abstracts at Goldschmidt2020 View abstracts at 9 conferences in series
Thomas Shea View all 7 abstracts at Goldschmidt2020 View abstracts at 6 conferences in series
Thomas Giachetti View abstracts at 4 conferences in series
Stefanie Brachfeld View abstracts at 2 conferences in series
Julia Hammer View all 5 abstracts at Goldschmidt2020 View abstracts at 9 conferences in series
Thomas Shea View all 7 abstracts at Goldschmidt2020 View abstracts at 6 conferences in series
Thomas Giachetti View abstracts at 4 conferences in series
Stefanie Brachfeld View abstracts at 2 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 Patrick Phelps on Wednesday 24th June 01:13
Hi Kelly, could you go into more detail why if the magnetite nucleates after vesicle formation, you would expect to see the susceptibility to be correlated with vesicularity? Are you thinking the magnetite would nucleate on the vesicles?
Susceptibility is indicative of magnetic grain abundance (as it can be used to calculate vol% of the present mineral). Minerals like titanomagnetite form in oxidizing environments. Bubbles in melt can provide an oxidizing environment that may preferentially nucleate titanomagnetite along the boarders of the bubble. In a magma the connected bubble pathways would provide the most surface area for this oxidizing environment. By comparing susceptibility to connected vesicularly, we can investigate the potential of this scenario. If this was the case, with increasing connected vesicularly we should see more magnetic particles (increasing susceptibility), however in my samples this does not occur (no trend can be seen). Leading me to determine the titanomagnetite formed prior to bubble growth. Hope that answers your question.
Hi Kelly, could you go into more detail why if the magnetite nucleates after vesicle formation, you would expect to see the susceptibility to be correlated with vesicularity? Are you thinking the magnetite would nucleate on the vesicles?
Susceptibility is indicative of magnetic grain abundance (as it can be used to calculate vol% of the present mineral). Minerals like titanomagnetite form in oxidizing environments. Bubbles in melt can provide an oxidizing environment that may preferentially nucleate titanomagnetite along the boarders of the bubble. In a magma the connected bubble pathways would provide the most surface area for this oxidizing environment. By comparing susceptibility to connected vesicularly, we can investigate the potential of this scenario. If this was the case, with increasing connected vesicularly we should see more magnetic particles (increasing susceptibility), however in my samples this does not occur (no trend can be seen). Leading me to determine the titanomagnetite formed prior to bubble growth. Hope that answers your question.
Submitted by Karen Spaleta on Wednesday 24th June 09:03
What advantage does doing magnetic analysis techniques to detect and characterize titanomagnetite give over X-ray techniques like the microprobe or EDS?
Given the small scale of the titanomagnetite (nm), techniques like mircroprobe or EDS would be difficult to apply as there resolutions typically fall within the um range. Magnetic analysis allows the detection of nm scale titanomagnetite, and allows for the sample to be left intact for additional analysis. I do hope to eventually apply X-ray computed Tomography to investigate the spatial relationship between the titanomagnetite and vesicles present in the sample, as variations of this technique allow for the resolution of nm scale particles.
What advantage does doing magnetic analysis techniques to detect and characterize titanomagnetite give over X-ray techniques like the microprobe or EDS?
Given the small scale of the titanomagnetite (nm), techniques like mircroprobe or EDS would be difficult to apply as there resolutions typically fall within the um range. Magnetic analysis allows the detection of nm scale titanomagnetite, and allows for the sample to be left intact for additional analysis. I do hope to eventually apply X-ray computed Tomography to investigate the spatial relationship between the titanomagnetite and vesicles present in the sample, as variations of this technique allow for the resolution of nm scale particles.
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