Abstract Details
(2020) The Modern Upper Crust is Altered and the Archean Upper Crust was Andesitic: Results from a Novel Analysis of Major Element Data
Lipp A, Shorttle O, Syvret F, Roberts G & Sediment Geochemistry & Paleoenvironments Project WIWG
https://doi.org/10.46427/gold2020.1575
The author has not provided any additional details.
03e: Room 1, Thursday 25th June 06:45 - 06:48
Alexander Lipp
View all 2 abstracts at Goldschmidt2020
Oliver Shorttle View all 7 abstracts at Goldschmidt2020 View abstracts at 12 conferences in series
Frank Syvret
Gareth Roberts
Weathering Intensity Working Group Sediment Geochemistry & Paleoenvironments Project
Oliver Shorttle View all 7 abstracts at Goldschmidt2020 View abstracts at 12 conferences in series
Frank Syvret
Gareth Roberts
Weathering Intensity Working Group Sediment Geochemistry & Paleoenvironments Project
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 Kent Condie on Thursday 18th June 23:56
Alex, enjoyed your paper very much. I have one important question: Sediment compositions vary also with tectonic setting (for instance you really can't compare quartz arenites from a passive margin with volcanogenic sediments in and arc). Did you take this into account in your studies? Ross Taylor and colleagues made this mistake many years ago by comparing mature sediments in the post Archean with largely volcanogenic graywackes in the Archean. (kent.condie@nmt.edu)
Hi Kent, I'm very glad to hear you enjoyed the paper! So we didn't explicitly take into account variation in tectonic setting, i.e., our database is a mixture of different tectonic settings through time. In most cases we haven't assigned a setting to it (if its even possible to do that reliably in deep time). However, I think that you're absolutely right that what is interpreted as a secular change in crustal composition could be a secular change in the tectonic settings preserved in the stratigraphic record. As a result, in the manuscript we're preparing we're going to include a substantial discussion about this potential issue however it wasn't possible to delve too much into the nuance of this in the presentation. Ultimately we're always hamstrung with what the stratigraphic record has and has not preserved, and there are certainly scenarios (like the one you indicate) whereby secular changes in preserved tectonic settings give the 'illusion' of changing crustal composition. Given these issues, it might be more accurate to refer to our calculated crustal compositions as 'average preserved protolith' instead of 'crustal composition'. Best, Alex PS Which Taylor paper is this, I'll be sure to give it a read if I haven't already.
Alex, enjoyed your paper very much. I have one important question: Sediment compositions vary also with tectonic setting (for instance you really can't compare quartz arenites from a passive margin with volcanogenic sediments in and arc). Did you take this into account in your studies? Ross Taylor and colleagues made this mistake many years ago by comparing mature sediments in the post Archean with largely volcanogenic graywackes in the Archean. (kent.condie@nmt.edu)
Hi Kent, I'm very glad to hear you enjoyed the paper! So we didn't explicitly take into account variation in tectonic setting, i.e., our database is a mixture of different tectonic settings through time. In most cases we haven't assigned a setting to it (if its even possible to do that reliably in deep time). However, I think that you're absolutely right that what is interpreted as a secular change in crustal composition could be a secular change in the tectonic settings preserved in the stratigraphic record. As a result, in the manuscript we're preparing we're going to include a substantial discussion about this potential issue however it wasn't possible to delve too much into the nuance of this in the presentation. Ultimately we're always hamstrung with what the stratigraphic record has and has not preserved, and there are certainly scenarios (like the one you indicate) whereby secular changes in preserved tectonic settings give the 'illusion' of changing crustal composition. Given these issues, it might be more accurate to refer to our calculated crustal compositions as 'average preserved protolith' instead of 'crustal composition'. Best, Alex PS Which Taylor paper is this, I'll be sure to give it a read if I haven't already.
Submitted by Alex Lipp on Monday 22nd June 12:46
Hi Kent, I'm very glad to hear you enjoyed the paper! So we didn't explicitly take into account variation in tectonic setting, i.e., our database is a mixture of different tectonic settings through time. In most cases we haven't assigned a setting to it (if its even possible to do that reliably in deep time). However, I think that you're absolutely right that what is interpreted as a secular change in crustal composition could be a secular change in the tectonic settings preserved in the stratigraphic record. As a result, in the manuscript we're preparing we're going to include a substantial discussion about this potential issue however it wasn't possible to delve too much into the nuance of this in the presentation. Ultimately we're always hamstrung with what the stratigraphic record has and has not preserved, and there are certainly scenarios (like the one you indicate) whereby secular changes in preserved tectonic settings give the 'illusion' of changing crustal composition. Given these issues, it might be more accurate to refer to our calculated crustal compositions as 'average preserved protolith' instead of 'crustal composition'. Best, Alex PS Which Taylor paper is this, I'll be sure to give it a read if I haven't already.
Hi Kent, I'm very glad to hear you enjoyed the paper! So we didn't explicitly take into account variation in tectonic setting, i.e., our database is a mixture of different tectonic settings through time. In most cases we haven't assigned a setting to it (if its even possible to do that reliably in deep time). However, I think that you're absolutely right that what is interpreted as a secular change in crustal composition could be a secular change in the tectonic settings preserved in the stratigraphic record. As a result, in the manuscript we're preparing we're going to include a substantial discussion about this potential issue however it wasn't possible to delve too much into the nuance of this in the presentation. Ultimately we're always hamstrung with what the stratigraphic record has and has not preserved, and there are certainly scenarios (like the one you indicate) whereby secular changes in preserved tectonic settings give the 'illusion' of changing crustal composition. Given these issues, it might be more accurate to refer to our calculated crustal compositions as 'average preserved protolith' instead of 'crustal composition'. Best, Alex PS Which Taylor paper is this, I'll be sure to give it a read if I haven't already.
Sign in to ask a question.