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SUMMARY:Meteorite paleomagnetism: Constraints on the rearrangement of the 
 planets and the formation of the first solids  - James Bryson (Earth Scien
 ces\, Cambridge)
DTSTART:20171023T130000Z
DTEND:20171023T140000Z
UID:TALK85701@talks.cam.ac.uk
CONTACT:Dr. Yufeng Lin
DESCRIPTION:It has been suggested that there were at least two major plane
 tary rearrangements within the first 1 Gyr of our solar system. Such event
 s are believed to have played a crucial role in shaping the present-day ar
 chitecture our solar system as well as possibly those of exoplanetary syst
 ems. Within our own solar system\, planetary migrations have been proposed
  to have brought material that formed beyond the orbit of the gas giants i
 nto the inner solar system\, possibly explaining the compositional trends 
 across the asteroid belt as well as the makeup of the Trojan asteroids. Ho
 wever\, very few robust\, accurate or quantitative estimates of the helioc
 entric distances of the formation of meteorite parent bodies exist. These 
 distance estimates would also constrain the range over which the first sol
 ids (chondrules and calcium-aluminium-rich inclusions [CAIs]) may have for
 med or have been recycled throughout the solar system by stellar outflows.
 \nHere\, we present paleomagnetic evidence that the Tagish Lake meteorite 
 does not contain a stable magnetic remanence. Given the ancient aqueous al
 teration age of this meteorite (<4 Myr after CAI formation)\, this absence
  suggests that the Tagish Lake parent body must have originated from >10 -
  20 AU where the magnetic field generated by the collapse of the dust and 
 gas within the nebula was %<% 0.15 µT. This distance corresponds to radii
  greater than the orbits of the gas giants prior to the migrations involve
 d in Grand Tack\, suggesting the Tagish Lake parent body represents outer 
 disk bodies that now constitute the Kuiper belt and could therefore feasib
 ly be a comet. Tagish Lake contains sparse chondrules and even rare CAIs\,
  indicating that stellar outflows were capable of transporting solid mater
 ial that formed within 1 AU of the Sun and within 1 Myr of CAI formation t
 o distances as far as that of present-day Saturn or Uranus. Finally\, our 
 results provide a quantitative observation from the meteorite record that 
 a body formed in the outer solar system and now resides in the inner solar
  system\, supporting the presence of major ancient planetary migrations th
 at altered the architecture and structure of our solar system. 
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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