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SUMMARY:Ophiolite insights into the oxygen isotope composition of the Camb
 rian ocean - Dr Sasha Turchyn (University of Cambridge)
DTSTART:20150313T170000Z
DTEND:20150313T173000Z
UID:TALK58439@talks.cam.ac.uk
CONTACT:Jack Wright
DESCRIPTION:One of the most enigmatic questions in paleoceanography is whe
 ther there has been secular variation in the oxygen isotope composition of
  the ocean over the last 550 million years.  Well preserved carbonate rock
 s and fossils suggest early Phanerozoic oceans that may have been as much 
 as 4-5‰ lower than today\, but many models and other mineral proxies hav
 e failed to reproduce this.  In this talk I will discuss an attempt made t
 o address this issue by using paired vein mineral analysis to reconstruct 
 the oxygen isotope composition of hydrothermal vent fluid in the late Camb
 rian (500 million years ago) from ophiolites in Newfoundland.  The data is
  considered in both a stagnant (water/rock ratio) and reactive transport c
 ontext\, and the results are enigmatic.  Water-rock interaction in hydroth
 ermal systems may be a function of the major ion chemistry of the ocean ov
 er the course of Earth history\, which may offer new insight into the modu
 lation of chemical fluxes within hydrothermal systems.
LOCATION:Tilley Lecture Theater\, Department of Earth Sciences
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