Abstract Details
(2020) Ruthenium Isotopic Evidence for a Missing Late Accretion Component in the Mantle Source of Pilbara Craton
Fischer-Gödde M, Münker C, Becker H, Wolfgang M, Van Kranendonk M & Smithies H
https://doi.org/10.46427/gold2020.719
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02c: Room 1, Tuesday 23rd June 22:27 - 22:30
Mario Fischer-Gödde
View all 3 abstracts at Goldschmidt2020
Carsten Münker View all 9 abstracts at Goldschmidt2020 View abstracts at 22 conferences in series
Harry Becker View all 3 abstracts at Goldschmidt2020 View abstracts at 19 conferences in series
Maier Wolfgang
Martin J Van Kranendonk View all 3 abstracts at Goldschmidt2020 View abstracts at 2 conferences in series
Hugh Smithies View all 2 abstracts at Goldschmidt2020 View abstracts at 7 conferences in series
Carsten Münker View all 9 abstracts at Goldschmidt2020 View abstracts at 22 conferences in series
Harry Becker View all 3 abstracts at Goldschmidt2020 View abstracts at 19 conferences in series
Maier Wolfgang
Martin J Van Kranendonk View all 3 abstracts at Goldschmidt2020 View abstracts at 2 conferences in series
Hugh Smithies View all 2 abstracts at Goldschmidt2020 View abstracts at 7 conferences in series
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Submitted by Daniel Stubbs on Tuesday 23rd June 13:42
Hi Mario! Great talk on the new Ru data. I'm interested in the new Pilbara data compared to the Pilbara data that you published in your 2020 paper. The ones that you have published have no resolved Ru anomaly, but the ones in this talk do. How do you explain this? Also, Jonas has measured a sample with no W anomaly at ~3.2 Ga, but you have identified a sample that is 2.99 Ga that still has a Ru anomaly (the largest that you have measured for Pilbara). Jonas' 182W data suggests a late veneer component was added to Pilbara before 3.2 Ga, but the 2.99 Ga Croydon sample you measured Ru on has the greatest anomaly - how would you explain this discrepancy? (admittedly, they are different samples)
Hi Daniel, many thanks for your interest in our work. The Pilbara sample analyzed in our previous paper, which you are referring to (Pil 16-61), is a chromitite for which unfortunately we do not exactly know the exact stratigraphic age. I am not sure why the chromitite does not show the same anomaly as observed for the komatiites. One explanation could be that the chromitite is actually younger than we think and therefore would derive from a mantle that already contained the full late veneer component. The sample with the largest Ru isotope anomaly derives from a metasomatized lithospheric mantle source that was refertilized by subducted sediment components. Owing to the mobility of W in crustal settings it is therefore more complex to interpret the 182W signature of this sample. However, Ru would behave much less mobile under these conditions. This could explain the obvious mismatch between the 182W and the 100Ru data. In this case the 100Ru signature would reflect the ancient lithospheric mantle component. To solve these issues, we definitely need a more comprehensive data set covering the whole stratigraphic sequence.
Hi Mario! Great talk on the new Ru data. I'm interested in the new Pilbara data compared to the Pilbara data that you published in your 2020 paper. The ones that you have published have no resolved Ru anomaly, but the ones in this talk do. How do you explain this? Also, Jonas has measured a sample with no W anomaly at ~3.2 Ga, but you have identified a sample that is 2.99 Ga that still has a Ru anomaly (the largest that you have measured for Pilbara). Jonas' 182W data suggests a late veneer component was added to Pilbara before 3.2 Ga, but the 2.99 Ga Croydon sample you measured Ru on has the greatest anomaly - how would you explain this discrepancy? (admittedly, they are different samples)
Hi Daniel, many thanks for your interest in our work. The Pilbara sample analyzed in our previous paper, which you are referring to (Pil 16-61), is a chromitite for which unfortunately we do not exactly know the exact stratigraphic age. I am not sure why the chromitite does not show the same anomaly as observed for the komatiites. One explanation could be that the chromitite is actually younger than we think and therefore would derive from a mantle that already contained the full late veneer component. The sample with the largest Ru isotope anomaly derives from a metasomatized lithospheric mantle source that was refertilized by subducted sediment components. Owing to the mobility of W in crustal settings it is therefore more complex to interpret the 182W signature of this sample. However, Ru would behave much less mobile under these conditions. This could explain the obvious mismatch between the 182W and the 100Ru data. In this case the 100Ru signature would reflect the ancient lithospheric mantle component. To solve these issues, we definitely need a more comprehensive data set covering the whole stratigraphic sequence.
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