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9 P-T-t paths.ppt

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					P-T-t Paths and Their Significance
   Metamorphic Field Gradient –Trend of
Thermal Maxima Across Metamorphic Facies
Clockwise P-T-t Path
P-T-t Path Reflecting Crustal Thickening
A Crustal Thickening P-T-t Path
 Central Indian
 Tectonic Zone
 (Proterozoic)
                          P-T-t Path for
                           Connemara
                              Inlier




Early Barrovian P-T-t
Path showing effects
of later arc-related
magmatism and
variable uplift/erosion
P-T-t Path of Burial Metamorphism


                     Field gradient 25 oC/Km
Subduction and exhumation in 10 Ma. Prograde,
retrograde stages of a single metamorphic cycle
     Alpine orogeny, Rhodope Region, Greece
                                          (1, 2) Gt-hbl thermometry
                                          Gt-amph-plag-qtz
                               10 oC/Km   barometry
                                          (3) Jd-Ky isograd
                                          (eclogite facies)
                                          (4) Plag-Cor isograd
                                          (granulite facies)
                                          5) Gt-Hbl thermometry,
                                          gt-amph-plag-qtz
                    30 oC/Km              barometry

                                           SHRIMP U-Pb dating
                                           of zircon

                                          Liati and Gebauer, 1999
  Clockwise P-T-t Path in a Back-Arc Basin
ODP Site 976 between Spain and Morocco – Miocene
extensional basin
Exhumation in 6 Ma @ 4km/Ma
Alpine Uplift Rates from Geothermobarometry
              and 40Ar-39Ar Dating



                                    20 Ma   Uplift Rate
                                             mm/an
                                18 Ma
                                                 3.6

                                                2.9
                            18 Ma
                        13.3 Ma                 1.8
               7.1 Ma                           0.5
Counter Clockwise P-T-t Paths
  Counter-clockwise Path –Commonly
Occurs Under Granulite Facies Conditions
Counter clockwise P-T-t Path –
  Archean Granulite Terrane
Proterozoic Metamorphism N. Australia



                   LP       HP
Counter-clockwise Paths
 in HP and LP Granulite
        Terranes
Clockwise P-T-t
Path for Granulite
Facies, Scotland
Variscan Clockwise and
  Counter-clockwise
Paths in the Odenwald,
       Germany

				
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posted:3/22/2012
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