BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//talks.cam.ac.uk//v3//EN
BEGIN:VTIMEZONE
TZID:Europe/London
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:BST
DTSTART:19700329T010000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:GMT
DTSTART:19701025T020000
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
CATEGORIES:Bullard Laboratories Wednesday Seminars
SUMMARY:Geodynamic constraints on early Earth crust format
 ion and tectonics - Brad Foley -- Penn State Unive
 rsity
DTSTART;TZID=Europe/London:20240605T140000
DTEND;TZID=Europe/London:20240605T150000
UID:TALK216454AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/216454
DESCRIPTION:A unique feature of the Earth compared to the othe
 r rocky planets of our solar system is the operati
 on of plate tectonics at the present day. However\
 , how and when Earth developed into this present-d
 ay state is unclear. Key to deciphering Earth’s lo
 ng-term tectonic evolution is the growth of the fi
 rst continents\, as these represent the oldest ext
 ant rock record providing our best window into the
  geodynamic processes of the very early Earth. Ear
 ly continental crust has been proposed to form by 
 a variety of mechanisms\, some involving plate tec
 tonics and some not. End-member models of early co
 ntinental crust formation include melting hydrated
  mafic rocks at the base of a thick\, volcanically
  active oceanic crustal plateau\, a process not re
 quiring plate tectonics\, and melting of mafic cru
 st during subduction\, a process compatible with p
 late tectonics. I use numerical models of early Ea
 rth mantle convection and crust formation\, combin
 ed with key geochemical observations\, to provide 
 new constraints on these models. I show that conti
 nental crust formation by slab melting during subd
 uction can only occur when subduction is sluggish 
 and present a new mechanism for such subduction on
  the early Earth. I further show how continent for
 mation by ocean plateau melting and by slab meltin
 g can combine to explain observations from the Arc
 hean geologic record\, with implications for Earth
 's long-term tectonic evolution. 
LOCATION:Wolfson Lecture Theatre
CONTACT:Adriano Gualandi
END:VEVENT
END:VCALENDAR