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SUMMARY:Predictive and invertible models of sediment geochemistry from cat
 chment to continental scales - Alex Lipp\, Imperial College London 
DTSTART:20210215T170000Z
DTEND:20210215T180000Z
UID:TALK154957@talks.cam.ac.uk
CONTACT:James Craig
DESCRIPTION:Sediments are weathered pieces of rocks that are mixed in rive
 rs (mostly) and transported to basins\, becoming sorted along the way. Thi
 s conceptual understanding of sediment formation has been generally unders
 tood for many years\, although recent updates to this understanding are st
 ill made (e.g. the importance of cation exchange). Here I will show how th
 is conceptual understanding can be represented using quantitative schemes 
 to make predictions about sedimentary geochemistry and improve our underst
 anding of Earth's surface. First\, I demonstrate a statistical method to d
 escribe the major-element composition of sediments in terms of the composi
 tion of their protolith and how intensely they have been weathered. Applyi
 ng this method to large compilations of sediment compositions allows us to
  reconstruct the composition of the Archean continents\, and produce a Pha
 nerozoic history of weathering intensity. Second\, I show how modern-day r
 iver sediments can be reliably predicted using a simple mixture model of t
 heir source regions. Finally\, I show how this mixing model can be 'invert
 ed'\, allowing higher order river sediments to be 'unmixed' to produce geo
 chemical maps of their source regions.  
LOCATION:The talk will be held virtually over zoom. The link will be circu
 lated to members via email\, while non-members may contact jac293@cam.ac.u
 k for details
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