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SUMMARY:Dates\, Rates\, Ages and Stages: New developments in determining m
 etamorphic timescales - Dr Clare Warren (Open University)
DTSTART:20141124T170000Z
DTEND:20141124T180000Z
UID:TALK54362@talks.cam.ac.uk
CONTACT:Jack Wright
DESCRIPTION:The incorporation of naturally-decaying radioactive elements i
 nto different minerals allows geologists to use them as geological 'clocks
 '.  The accurate and precise determination of the ages of these minerals\,
  and different crystallisation zones within them\, allows the timing\, rat
 es and timescales of tectonic processes to be determined.  However in orde
 r to reliably interpret 'dates' as geologically meaningful 'ages'\, the cr
 ystallisation reactions of these minerals need firstly to be determined\, 
 and secondly to be linked to the reaction history of the major rock-formin
 g minerals.  These latter minerals preserve information about the pressure
 \, temperature and transport history. Linking the crystallisation history 
 of the accessory to the major phases is particularly important in metamorp
 hic rocks\, as these commonly record complex histories.\n\nRecent advances
  in in-situ analysis\, such as by laser ablation or secondary ion sputteri
 ng\, allow increasingly precise information to be yielded from smaller vol
 umes of material.  Furthermore\, trace element concentrations and ratios a
 ct as 'fingerprints' that allow the formation and dissolution of the geoch
 ronometers to be linked to the evolution recorded by the main rock-forming
  minerals\n\nThis talk will focus on two recent developments in linking 'a
 ge to stage': firstly determining the crystallisation history of the high 
 grade metamorphic rocks that form the core of the Himalayan mountain belt\
 , and secondly unravelling the exhumation history recorded by Ar/Ar ages f
 rom the Western Gneiss Region in Norway.  Both regions provide a rich mine
  of information about the tectonic processes operating deep within mountai
 n belts\, allowing information from the present to be compared to the past
 .\n\nClare Warren is a NERC Advanced Postdoctoral Fellow at the Open Unive
 rsity\, UK.  She gained her BA and DPhil at Oxford\, and has been at the O
 U since 2008.  She has published >25 papers  on the formation and evolutio
 n of mountain belts\, using geochronological\, petrogenetic modelling and 
 geodynamic modelling tools.  Her research focuses on resolving the rates a
 nd timescales of metamorphic processes during the early (high pressure) an
 d middle (high temperature) stages of continental collision.  At the momen
 t she is trying to improve techniques to link metamorphic  U-Pb and Ar/Ar 
 'age' to metamorphic 'stage' using trace element reaction fingerprinting t
 echniques.
LOCATION:Harker Room 1\, Department of Earth Sciences
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