[thesis swamp] continues :|

Utterly stuck on sorting out a subsection of the discussion in chapter 4, to the point where I am Taking A Decided Break and just. Wrangling typesetting ch3 (as both preprint and thesis chapter) instead. Which at least is getting me measurable progress! So maybe I will come back to this chunk tomorrow, or maybe I will skip ahead to the next one and see if that's less stuck-for-multiple-days, or maybe I'll try writing it up here, who knows.

(Short version: oceanic crust is formed at mid-ocean ridges and then gets mixed back into the mantle at subduction zones. Thallium gets added to the oceanic crust while water is swooshing around it and via sediments, which we can tell by taking a big chunk of rock and grinding it up and just measuring the Tl in the "whole rock", as it's called. We can also, however, look at how Tl concentrations vary with the concentrations of other elements -- if we can't be bothered picking the rock apart into its separate constituents, for whatever reason -- and that lets us go "ah, when the sulphur concentration goes up so does the Tl, so probably Tl is being hosted in sulphides" or whatever. Which is why we're p sure a bunch of the Tl in the upper altered ocean crust is hosted in sulphides... but this bit of the explanation isn't the one I need to give in the subsection I'm stuck on; instead, I need to talk apparently simultaneously about both (1) Tl once it's been erupted in arc lavas, and (2) how it gets into arc lavas in the first place, and... okay actually maybe the way to structure this is to sodding talk about processes instead of trying to do it chronologically, thank you all, I'll have another think about this after I've slept though I'm not hopeful it'll stick. But, hey, maybe leaving it to stew will get me somewhere eventually.)