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SUMMARY:The history of the global carbon cycle as recorded by the chemical
  composition of shallow-water marine carbonate sediments - John Higgins\, 
 Princeton University
DTSTART:20211007T140000Z
DTEND:20211007T150000Z
UID:TALK162787@talks.cam.ac.uk
CONTACT:Oscar Branson
DESCRIPTION:Shallow-water carbonate sediments are one of the most importan
 t geologic sinks of CO2 emitted from Earth’s interior and a widely used 
 archive of Earth's chemical and climate history.  Some of the main limitat
 ions in interpreting the chemistry of ancient carbonate sediments include 
 the potential for post-depositional diagenetic alteration and uncertaintie
 s in how to relate chemical changes in shallow-water environments to the g
 lobal carbon cycle. In this talk I will discuss my labs efforts – using 
 measurements of the stable isotopes of calcium\, magnesium\, and lithium -
  to disentangle the effects of diagenesis and local processes in ancient s
 hallow-water marine carbonates in order to more accurately reconstruct the
  chemical composition of seawater in the geologic past.  I will argue that
  our results are inconsistent with the commonly-used approach of using str
 atigraphic excursions in carbon and other geochemical proxies in shallow-w
 ater marine carbonate sediments as quantitative indicators of global isoto
 pic mass balance. 
LOCATION:Department of Earth Sciences\, Tilley Lecture Theatre
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