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SUMMARY:The link between the global carbon cycle and the interplay between
  calcium and sulfur in marine pore fluid - Hal Bradbury | University of Ca
 mbridge
DTSTART:20210608T100000Z
DTEND:20210608T113000Z
UID:TALK160945@talks.cam.ac.uk
CONTACT:87364
DESCRIPTION:The removal of carbon from the surface of the planet is a crit
 ical component of the long-term carbon cycle\; this removal is through the
  deposition and subsequent burial of carbonate minerals in the ocean. Sedi
 mentary\, post-depositional processes play a key role in the global carbon
  cycle because much of the organic carbon in sediments is microbially oxid
 ized back to dissolved inorganic carbon. The oxidation of organic carbon i
 n anaerobic sediment through the reduction of sulfate can consume protons\
 , raising pH\, and leading to some of the dissolved inorganic carbon preci
 pitating as in situ\, or authigenic carbonate. Because this authigenic car
 bonate has a different carbon isotope composition to marine carbonate\, it
  may influence the overall carbon isotope balance at Earth’s surface and
  critically\, our interpretation of global shifts in the carbon cycle over
  geological time. In today’s ocean the two main processes that produce a
 lkalinity and drive authigenic carbonate formation are the organoclastic r
 eduction of sulfate and the anaerobic oxidation of methane\, coupled to mi
 crobial sulfate reduction.\n\nI will discuss how we can identify the proce
 sses that are linked to the precipitation of authigenic carbonate\, and ho
 w we can utilise the global ODP/IODP pore fluid database to examine these 
 processes on a global scale. Here we concentrate on the relative change in
  alkalinity\, methane and sulfate concentrations to predict regions of ana
 erobic methane oxidation versus organoclastic sulfate reduction and the re
 lative decrease in calcium concentration to predict the amount of authigen
 ic carbonate formed. I will present a machine-learning approach to identif
 y the distribution of these processes in the modern ocean tuned with chlor
 ophyll\, temperature\, water depth and distance from the coast to predict 
 the extent of anaerobic methane oxidation versus organoclastic sulfate red
 uction to extend the sites with observations to those areas that have none
 . A reactive transport model is then used to discuss how the formation of 
 authigenic carbonate would have been impacted by varying sulfate and calci
 um concentrations found in Phanerozoic seawater.
LOCATION:https://zoom.us/j/6708259482?pwd=Qk03U3hxZWNJZUZpT2pVZnFtU2RRUT09
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