PTt Paths and Their Significance Metamorphic Field Gradient

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 o. C/Km

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

Alpine Uplift Rates from Geothermobarometry and 40 Ar-39 Ar Dating 20 Ma 18 Ma 13. 3 Ma 7. 1 Ma Uplift Rate mm/an 3. 6 2. 9 1. 8 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