Abstract Details
(2020) Volcanic Evolution of the Kauaʻi Shield, Northern Hawaiian Islands
Williamson N, Weis D & Scoates J
https://doi.org/10.46427/gold2020.2873
The author has not provided any additional details.
05h: Room 2, Saturday 27th June 06:12 - 06:15
Nicole Williamson
View all 3 abstracts at Goldschmidt2020
View abstracts at 2 conferences in series
Dominique Weis View all 12 abstracts at Goldschmidt2020 View abstracts at 22 conferences in series
James S. Scoates View all 3 abstracts at Goldschmidt2020 View abstracts at 2 conferences in series
Dominique Weis View all 12 abstracts at Goldschmidt2020 View abstracts at 22 conferences in series
James S. Scoates View all 3 abstracts at Goldschmidt2020 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 Keith Putirka on Wednesday 24th June 21:51
Hi Nicole - this looks like a really important study. After seeing Karen Harpp's model for Galapagos, I'm wondering if her ideas might apply here: is enough room in plate motion studies to allow Kauai to have started completely on the Loa side of the bilateral plume, and then drift/rotate north, into the Kea region (and so perhaps the surface expression of isotopes, at least for older/smaller volcanoes, might tell us less about plume geometry and more about magma plumbing and plate motions). I am assuming that panel 4 shows a strat column and that Kea-stuff is youngest. -Keith
Hi Keith, thank you for your question. You are exactly right and we wrote about this last year, using Pb isotopes for Kaua‘i and the other northern Hawaiian islands. The western part of Kaua‘i is oldest, and Kea-like, whereas the eastern part of Kaua‘i is youngest, and Loa-like. We think that this supports a different plate motion direction prior to 2 Ma, so that when Kaua‘i was forming, it sampled the Kea side of the plume first followed by the Loa side. The abstract we're presenting at this Goldschmidt summarizes the next part of the story, which takes all the other data we collected for Kaua‘i (isotopes, major and trace elements, olivine compositions, argon ages) and addresses some of the Kaua‘i-specific questions such as timing and source of each shield unit, 1 or 2 volcanoes, etc. Average ages for west and east Kaua‘i are at the top of panel 4. Here's a link to the 2019 paper, but I'm happy to send it along if you would like: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GC008451 - Nicole
Hi Nicole - this looks like a really important study. After seeing Karen Harpp's model for Galapagos, I'm wondering if her ideas might apply here: is enough room in plate motion studies to allow Kauai to have started completely on the Loa side of the bilateral plume, and then drift/rotate north, into the Kea region (and so perhaps the surface expression of isotopes, at least for older/smaller volcanoes, might tell us less about plume geometry and more about magma plumbing and plate motions). I am assuming that panel 4 shows a strat column and that Kea-stuff is youngest. -Keith
Hi Keith, thank you for your question. You are exactly right and we wrote about this last year, using Pb isotopes for Kaua‘i and the other northern Hawaiian islands. The western part of Kaua‘i is oldest, and Kea-like, whereas the eastern part of Kaua‘i is youngest, and Loa-like. We think that this supports a different plate motion direction prior to 2 Ma, so that when Kaua‘i was forming, it sampled the Kea side of the plume first followed by the Loa side. The abstract we're presenting at this Goldschmidt summarizes the next part of the story, which takes all the other data we collected for Kaua‘i (isotopes, major and trace elements, olivine compositions, argon ages) and addresses some of the Kaua‘i-specific questions such as timing and source of each shield unit, 1 or 2 volcanoes, etc. Average ages for west and east Kaua‘i are at the top of panel 4. Here's a link to the 2019 paper, but I'm happy to send it along if you would like: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GC008451 - Nicole
Submitted by Marie-Claude Williamson on Friday 26th June 02:11
Hi Nicole - following up on your answer to Keith Putirka's question: Can the isotopic data on the erupted lava pile resolve the question of 1 vs. 2 volcanic edifices? If not, what approach(es) could you use to constrain this particular aspect of the evolution of the Kaua'i Shield?
Thank you for your question! The isotopic data tells us that the source composition is changing from west to east across Kauai, however this alone can’t resolve the 1 vs. 2 volcano hypothesis. A lot of previous work has been done on interpreting Kaua‘i’s shield growth using geochemical data, field observations, geophysics, and paleomagnetic data, and by combining this work with the large dataset we’ve collected (and in particular the olivine compositions and argon ages) we’re able to constrain some of the ideas that have been previously proposed. I think that the key aspect is that the central shield units are transitional in chemistry and age with respect to the western and eastern parts of the island. I think that this points to a single magma chamber with a composition that changed in time, and that the central units record that transition. The locus of volcanism might have shifted from a western point source to a more eastern one, but with a single magma chamber, I think you would still consider that a single Hawaiian volcano.
Hi Nicole - following up on your answer to Keith Putirka's question: Can the isotopic data on the erupted lava pile resolve the question of 1 vs. 2 volcanic edifices? If not, what approach(es) could you use to constrain this particular aspect of the evolution of the Kaua'i Shield?
Thank you for your question! The isotopic data tells us that the source composition is changing from west to east across Kauai, however this alone can’t resolve the 1 vs. 2 volcano hypothesis. A lot of previous work has been done on interpreting Kaua‘i’s shield growth using geochemical data, field observations, geophysics, and paleomagnetic data, and by combining this work with the large dataset we’ve collected (and in particular the olivine compositions and argon ages) we’re able to constrain some of the ideas that have been previously proposed. I think that the key aspect is that the central shield units are transitional in chemistry and age with respect to the western and eastern parts of the island. I think that this points to a single magma chamber with a composition that changed in time, and that the central units record that transition. The locus of volcanism might have shifted from a western point source to a more eastern one, but with a single magma chamber, I think you would still consider that a single Hawaiian volcano.
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