Abstract Details
(2020) Three Billion Years of Continental Weathering and Implications for Marine Biogeochemistry
Dzombak R & Sheldon N
https://doi.org/10.46427/gold2020.635
09d: Room 3, Friday 26th June 08:03 - 08:06
Rebecca Dzombak
View abstracts at 2 conferences in series
Nathan Sheldon View all 2 abstracts at Goldschmidt2020 View abstracts at 3 conferences in series
Nathan Sheldon View all 2 abstracts at Goldschmidt2020 View abstracts at 3 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 Rebecca Dzombak on Friday 19th June 21:17
test question
I won't make the live Q&A session (it's 3 a.m. my time), so please leave questions here or email me if you'd like to chat about our results! Thanks! - Becca
test question
I won't make the live Q&A session (it's 3 a.m. my time), so please leave questions here or email me if you'd like to chat about our results! Thanks! - Becca
Submitted by Stefan Löhr on Thursday 25th June 13:44
Thanks for your thought provoking presentation. Your results suggest palaeosol composition has not changed over time. I was hoping you could comment on the likelihood this might reflect a dominant influence of burial diagenesis in palaeosols rather than persistent degrees of weathering over time. Also, very interested to see your results suggesting thicker palaeosols further back in time. Could part of this big apparent difference be because active soil vs regolith can be separated in more recent but perhaps not in Precambrian examples that have undergone extensive alteration, so the thickness reflects inclusion of saprolite/regolith excluded in more recent examples? Thanks!
Hi Stefan, thanks for your question! Re: burial diagenesis, that would mostly affect mineral composition as opposed to bulk geochemistry; K and maybe Ca could be affected, but we'd expect similar and systemic changes to those, which we don't really see (Ca does change through time). And re: regolith/active soil, we tried to address this identification problem by stopping the 'active soil' profile at the presence of corestones in weathering profiles, but it's possible that some thick profiles lacked corestones or a clear regolith boundary. Their geochemistries indicated single profiles. In building this dataset, as we got closer to the modern, alluvium/colluvium-parented or stacked fluvial paleosols outnumbered bedrock-parented soils. This affects the thickness distribution through time, but is also an interesting result in itself, possibly reflecting the shift in fluvial mechanisms after the spread of land plants. - Becca
Thanks for your thought provoking presentation. Your results suggest palaeosol composition has not changed over time. I was hoping you could comment on the likelihood this might reflect a dominant influence of burial diagenesis in palaeosols rather than persistent degrees of weathering over time. Also, very interested to see your results suggesting thicker palaeosols further back in time. Could part of this big apparent difference be because active soil vs regolith can be separated in more recent but perhaps not in Precambrian examples that have undergone extensive alteration, so the thickness reflects inclusion of saprolite/regolith excluded in more recent examples? Thanks!
Hi Stefan, thanks for your question! Re: burial diagenesis, that would mostly affect mineral composition as opposed to bulk geochemistry; K and maybe Ca could be affected, but we'd expect similar and systemic changes to those, which we don't really see (Ca does change through time). And re: regolith/active soil, we tried to address this identification problem by stopping the 'active soil' profile at the presence of corestones in weathering profiles, but it's possible that some thick profiles lacked corestones or a clear regolith boundary. Their geochemistries indicated single profiles. In building this dataset, as we got closer to the modern, alluvium/colluvium-parented or stacked fluvial paleosols outnumbered bedrock-parented soils. This affects the thickness distribution through time, but is also an interesting result in itself, possibly reflecting the shift in fluvial mechanisms after the spread of land plants. - Becca
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