BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Rapid temperature fluctuations in the early Iceland plume revealed
  by olivine-spinel and melt thermometry - Elliot Carter\, Trinity College 
 Dublin
DTSTART:20240220T120000Z
DTEND:20240220T130000Z
UID:TALK210193@talks.cam.ac.uk
CONTACT:Dr Rachael Rhodes
DESCRIPTION:The generation of Large Igneous Provinces (LIPs) – huge outp
 ourings of lavas associated with tectonic rifting – is a hotly debated t
 opic with competing models variously invoking hot mantle plumes\, insulati
 ve heating by supercontinents or edge driven convective instabilities. Man
 tle temperature and its temporal variation during LIP magmatism is key to 
 distinguishing between these different models. Despite this\, there are as
  yet no detailed stratigraphically constrained studies of mantle temperatu
 re through a LIP succession. \n\nTo address this\, we have applied olivine
 -spinel and melt-only thermometry to constrain mantle potential temperatur
 e through a sequence of lavas from Co. Antrim\, Northern Ireland\, formed 
 during the earliest expression of the North Atlantic Igneous Province. Man
 tle potential temperature derived from olivine-spinel and melt-only method
 s give consistent temperature ranges of 1374–1472°C and 1403–1521°C\
 , respectively. Notable both temperature records indicate significant (100
 -120°C) variation in melting temperature over a relatively short stratigr
 aphic during earlier forming magmas and much less variation in later forme
 d magmas\, suggesting initial instability or pulsing which stabilised with
  time. \n\nVariability in melting temperature is mirrored by proxies for c
 rustal and volcanic processes\; Ni contents of olivine are elevated (<3000
  ppm) in the same interval as the lowest melting temperatures indicating m
 ixing of primary and more evolved (MgO ~4%) melts\, resulting from low mag
 matic flux into the crust in this interval. The abundance and thickness of
  red weathering horizons capping lava flows is also significantly higher t
 hrough the succession where mantle temperature variation is highest\, indi
 cating prolonged repose periods between eruption and a stop-start rhythm t
 o volcanism in this interval. These unique observations indicate that volc
 anic\, crustal and mantle systems are intrinsically linked and show that t
 he tempo of volcanism\, mediated via variations in melt flux\, is ultimate
 ly driven from below by changing mantle temperature.
LOCATION:Department of Earth Sciences\, Tilley Lecture Theatre
END:VEVENT
END:VCALENDAR