Abstract Details
(2020) The Ferrar Continental Flood Basalt: A ~1.6 Ma Long Duration Evidenced by High-Precision 40Ar/39Ar Ages
Ware B, Jourdan F, Chiaradia M & Nebel O
https://doi.org/10.46427/gold2020.2811
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06n: Room 2, Wednesday 24th June 23:33 - 23:36
Bryant Ware
View all 2 abstracts at Goldschmidt2020
View abstracts at 8 conferences in series
Fred Jourdan View all 3 abstracts at Goldschmidt2020 View abstracts at 20 conferences in series
Massimo Chiaradia View all 2 abstracts at Goldschmidt2020
Oliver Nebel View all 6 abstracts at Goldschmidt2020
Fred Jourdan View all 3 abstracts at Goldschmidt2020 View abstracts at 20 conferences in series
Massimo Chiaradia View all 2 abstracts at Goldschmidt2020
Oliver Nebel View all 6 abstracts at Goldschmidt2020
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 Yuri Amelin on Wednesday 24th June 12:07
Are there rocks in the Ferrar province where both zircon U-Pb and plagioclase 40Ar/39Ar dates are obtained? If yes, how do they compare to each other?
Are there rocks in the Ferrar province where both zircon U-Pb and plagioclase 40Ar/39Ar dates are obtained? If yes, how do they compare to each other?
Submitted by Yankun Di on Wednesday 24th June 16:15
Do you have a temperature estimate of the magma evolution? Can the K-Ar systems in plagioclase be closed to record ages before zircon saturation?
Do you have a temperature estimate of the magma evolution? Can the K-Ar systems in plagioclase be closed to record ages before zircon saturation?
Submitted by Matthew Heizler on Wednesday 24th June 23:36
Enjoyed your presentation. If you have a 70%-30% mixture of compositionally different plagioclase grains, this should be readily determined by microprobe analyses of your bulk mineral separation - do you observe this? Have you considered a fractionation model for 40Ar relative to 39Ar to explain your climbing spectra? This is commonly observed in sanidine age spectra and it would predict 1-2 Ma age difference from initial heating steps to the final heating steps. This would not predict the differences between the samples, thus I agree you likely are seeing a spread in apparent ages of bulk samples. Lastly, Yuri's question is a good one. You show a model argon loss spectra for a 185 Ma plagioclase. Did you use a reasonable thermal history that would allow dissolution of older zircons, but only minor argon loss?
Enjoyed your presentation. If you have a 70%-30% mixture of compositionally different plagioclase grains, this should be readily determined by microprobe analyses of your bulk mineral separation - do you observe this? Have you considered a fractionation model for 40Ar relative to 39Ar to explain your climbing spectra? This is commonly observed in sanidine age spectra and it would predict 1-2 Ma age difference from initial heating steps to the final heating steps. This would not predict the differences between the samples, thus I agree you likely are seeing a spread in apparent ages of bulk samples. Lastly, Yuri's question is a good one. You show a model argon loss spectra for a 185 Ma plagioclase. Did you use a reasonable thermal history that would allow dissolution of older zircons, but only minor argon loss?
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