[Weyer] The combined Lu-Hf and Sm-Nd mineral-whole rock, and zircon U-Pb, REE and Hf isotope study of ultra high pressure rocks from the CCSD program

German Title: The combined Lu-Hf and Sm-Nd mineral-whole rock, and zircon U-Pb, REE and Hf isotope study of ultra high pressure rocks from the CCSD program

Abbreviation: 205

Current Status: completed with report

Main Applicant:Prof. Dr. Stefan Weyer

Resources Recipient

Other Persons

Prof. Dr. Gerhard Brey
Dr. Axel Gerdes

Conveyor Begin:
Conveyor End:
Conveyor Duration:
Year: 2006


Ultrahigh pressure (UHP) rocks from the Chinese Continental Scientific Drilling (CCSD) program were chosen to study the Sm-Nd and Lu-Hf isotope systems in combination with U-Pb LA-ICP-MS and SHRIMP dating of distinct zircon domains. First results show that the combined use of trace element and U-Th-Pb isotope compositions of zircon and PT information from their mineral inclusions, allow the linkage between U-Pb ages and metamorphic reactions. Inherited and metamorphic zircons were distinguished based on CL imaging, mineral inclusions, trace element contents and Hf isotope composition. Up to three phases of zircon growth or re-crystallisation can be identified in a single sample. The ages are interpreted to date the time of (1) prograde and (2) UHP metamorphism during Middle Triassic subduction, and (3) retrograde metamorphism during Late Triassic exhumation. Ongoing studies of the Hf isotope analyses of UHP zircon domains from different samples promise new insights in the understanding of the behaviour of the Lu-Hf system during UHP metamorphism. Preliminary Lu-Hf and Sm-Nd grt-cpx isochrones from CCSD and Dabie eclogites yield surprisingly uniform ages that are in average about 6-8 Myr younger than UHP zircons. The interpretation of these ages is yet not clear for us. A major focus of the applied period of the proposal will be the application of the different chronometers (U-Pb on zircons and Lu-Hf / Sm-Nd on garnet-cpx) on minerals from the same samples. These studies should clarify if the different chronometers applied to different rocks on various sections of the drill hole yield consistent results or date different events. They will thus (1) test the limitations and robustness of the analytical methods, (2) allow to distinguish between analytical and geological scatter, and (3) will contribute to a better understanding of the metamorphic evolution of the Sulu terrane.

Related Publications

Liu, Fulai, Gerdes, Axel, Liu, Pinghua (2012). "U–Pb, trace element and Lu–Hf properties of unique dissolution–reprecipitation zircon from UHP eclogite in SW Sulu terrane, eastern China" Gondwana Research 22 p169-183

Liu, F. L., Gerdes, A., Xue, H. M. (2009). "Differential subduction and exhumation of crustal slices in the Sulu HP-UHP metamorphic terrane: insights from mineral inclusions, trace elements, U-Pb and Lu-Hf isotope analyses of zircon in orthogneiss" Journal of Metamorphic Geology 27 p805-825

Liu, Fulai, Gerdes, Axel, Liou, Jahnguang, Liu, Pinghua (2009). "Unique coesite-bearing zircon from allanite-bearing gneisses: U-Pb, REE and Lu-Hf properties and implications for the evolution of the Sulu UHP terrane, China" European Journal of Mineralogy 21 p1225-1250

Schmidt, Alexander, Weyer, Stefan, Mezger, Klaus, Scherer, Erik E., Xiao, Yilin, Hoefs, Jochen, Brey, Gerhard P. (2008). "Rapid eclogitisation of the Dabie–Sulu UHP terrane: Constraints from Lu–Hf garnet geochronology" Earth and Planetary Science Letters 273 p203-213

Liu, Fulai, Gerdes, Axel, Zeng, Lingsen, Xue, Huaimin (2008). "SHRIMP U–Pb dating, trace elements and the Lu–Hf isotope system of coesite-bearing zircon from amphibolite in the SW Sulu UHP terrane, eastern China" Geochimica et Cosmochimica Acta 72 p2973-3000

Fulai, Liu, Gerdes, A, Robinson, PT, Huaimin, Xue, Jianguo, Ye (2007). "Zoned Zircon from Eclogite Lenses in Marbles from the Dabie‐Sulu UHP Terrane, China: A Clear Record of Ultra‐deep Subduction and Fast Exhumation" Acta Geologica Sinica (English edition) 81 (2) p204-225