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SUMMARY:G5a: the geology\, origin and celebrity of Shap Granite. - Dr Nige
 l Woodcock (University of Cambridge)
DTSTART:20171016T163000Z
DTEND:20171016T173000Z
UID:TALK86841@talks.cam.ac.uk
CONTACT:Charlie Eardley
DESCRIPTION:The Shap Granite of northwest England is famous not only as th
 e first rock that Cambridge Earth Sciences students see\, but more widely 
 as an ornamental stone with impressive K-feldspar megacrysts. The location
  of one prominent exposure of Shap Granite in Cambridge will be revealed.\
 n\nThe granite is one of the Trans-Suture suite\, intruded either side of 
 the recently closed Iapetus ocean in early Devonian time. The origin of th
 is post-subduction suite is still uncertain\, but melting was probably tri
 ggered by the heat pulse as the subducting slab broke off. The mechanism o
 f upper crustal emplacement is also puzzling\, overlapping as it does with
  the Acadian crustal shortening rather than with extension. Recent U-Pb zi
 rcon ages from the Shap Granite have clarified its emplacement age but hav
 e also revealed an unexpectedly long (20 Ma) magmatic history for the mid
 -crustal mush zone that fed the exposed plutons. \n\nThe Shap Granite is a
 lso famous in Quaternary studies. Its erratic boulders spread over northea
 st England were influential in persuading Victorian geologists that the su
 perficial ‘Drift’ had been deposited by ice and not by Noah’s Flood.
  Disturbingly\, the Flood theory is once more gaining favour.\n
LOCATION: Harker 1\, Department of Earth Sciences\, Downing Street
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