Abstract Details
(2020) The Seawater Sr/Ca Ratio in the Past 50 Myr from Bulk Carbonate Sediments Corrected for Diagenesis
Zhang S, Zhou R & DePaolo D
https://doi.org/10.46427/gold2020.3128
14b: Plenary Hall, Monday 22nd June 22:24 - 22:27
Shuo Zhang
View abstracts at 8 conferences in series
Renjie Zhou View abstracts at 3 conferences in series
Donald J. DePaolo View all 6 abstracts at Goldschmidt2020 View abstracts at 20 conferences in series
Renjie Zhou View abstracts at 3 conferences in series
Donald J. DePaolo View all 6 abstracts at Goldschmidt2020 View abstracts at 20 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 Ed Hathorne on Sunday 21st June 21:30
Hi. How safe is the assumption of a consistent biogenic partitioning over these time scales? Is there any evidence for a constant contribution to the biogenic carbonate from different organisms i.e. foraminifer / coccolith ratio? Thanks!
This is a great question. The Ksr for foram is around 0.15 while for coccolith is around 0.35. So a change in foraminifer/coccolith ratio will affect the average partitioning coefficient between bulk sediment and seawater. Unfortunately this assumption has to be made for any reconstruction of paleoseawater Sr. Our results are consistent with the Sr/Ca ratio reconstructed using pure forams, indicating that the assumption here does not cause too much inaccuracy.
Hi. How safe is the assumption of a consistent biogenic partitioning over these time scales? Is there any evidence for a constant contribution to the biogenic carbonate from different organisms i.e. foraminifer / coccolith ratio? Thanks!
This is a great question. The Ksr for foram is around 0.15 while for coccolith is around 0.35. So a change in foraminifer/coccolith ratio will affect the average partitioning coefficient between bulk sediment and seawater. Unfortunately this assumption has to be made for any reconstruction of paleoseawater Sr. Our results are consistent with the Sr/Ca ratio reconstructed using pure forams, indicating that the assumption here does not cause too much inaccuracy.
Submitted by Kimberly Lau on Monday 22nd June 19:30
Great talk, Shuo. I wanted to ask how the reconstructed K_Sr partition coefficient values compared with experimental results, and whether the variability of K_Sr after diagenesis from "initial" K_Sr can be explained via differences in carbonate mineralogy, etc. Thank you!
Hi Kim, the global average Ksr is reconstructed from seawater Sr/Ca ratio and represents the average removal of Sr/Ca by calcite and aragonite. This is different from the Ksr used to infer the seawater Sr/Ca ratio from carbonate sediments which is assumed to be a constant. Hope this clarifies the issue.
Great talk, Shuo. I wanted to ask how the reconstructed K_Sr partition coefficient values compared with experimental results, and whether the variability of K_Sr after diagenesis from "initial" K_Sr can be explained via differences in carbonate mineralogy, etc. Thank you!
Hi Kim, the global average Ksr is reconstructed from seawater Sr/Ca ratio and represents the average removal of Sr/Ca by calcite and aragonite. This is different from the Ksr used to infer the seawater Sr/Ca ratio from carbonate sediments which is assumed to be a constant. Hope this clarifies the issue.
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