caa a22 4500 467890005 CHVBK 20180406152746.0 cr unu---uuuuu 170328e20060901xx s 000 0 eng 10.1007/s00710-006-0155-3 doi (NATIONALLICENCE)springer-10.1007/s00710-006-0155-3 Sub-solidus Oligocene zircon formation in garnet peridotite during fast decompression and fluid infiltration (Duria, Central Alps) [Elektronische Daten] [J. Hermann, D. Rubatto, V. Trommsdorff] Summary: A garnet peridotite lens from Monte Duria (Adula nappe, Central Alps, Northern Italy) contains porphyroblastic garnet and pargasitic amphibole and reached peak metamorphic conditions of ∼830 C, ∼2.8 GPa. A first stage of near isothermal decompression to pressures <2.0 GPa is characterised by domains where fine grained spinel, clinopyroxene, orthopyroxene and amphibole form. The newly formed amphibole contains elevated levels of fluid mobile elements such as Rb, Ba and Pb indicating that recrystallization was assisted by infiltration of a crustal-derived fluid. Further decompression and cooling to ∼720 °C, 0.7-1.0 GPa associated with limited fluid influx is documented by the formation of orthopyroxene-spinel-amphibole symplectites around garnet. Zircon separated from this garnet peridotite exhibits two distinct zones. Domain 1 displays polygonal oscillatory zoning and high trace element contents. It contains clinopyroxene and amphibole inclusions with the same composition as the same minerals formed during the spinel peridotite equilibration, indicating that this domain formed under sub-solidus conditions during decompression and influx of crustal fluids. Domain 2 has no zoning and much lower trace element contents. It replaces domain 1 and is likely related to zircon recrystallization during the formation of the symplectites. SHRIMP dating of the two domains yielded ages of 34.2 ± 0.2 and 32.9 ± 0.3 Ma, respectively, indicating fast exhumation of the peridotite within the spinel stability field. We suggest that the Duria garnet peridotite originates from the mantle wedge above the tertiary subduction of the European continental margin and that it was assembled to the country rock gneisses between 34 and 33 Ma. Springer-Verlag, 2006 Hermann J. Research School of Earth Sciences, The Australian National University, Canberra, Australia aut Rubatto D. Research School of Earth Sciences, The Australian National University, Canberra, Australia aut Trommsdorff V. Institute for Mineralogy and Petrography, ETH-Zürich, 8092, Zürich, Switzerland aut Mineralogy and Petrology Springer-Verlag 88/1-2(2006-09-01), 181-206 0930-0708 88:1-2<181 2006 88 710 https://doi.org/10.1007/s00710-006-0155-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00710-006-0155-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hermann J. Research School of Earth Sciences, The Australian National University, Canberra, Australia aut NATIONALLICENCE 700 1- Rubatto D. Research School of Earth Sciences, The Australian National University, Canberra, Australia aut NATIONALLICENCE 700 1- Trommsdorff V. Institute for Mineralogy and Petrography, ETH-Zürich, 8092, Zürich, Switzerland aut NATIONALLICENCE 773 0- Mineralogy and Petrology Springer-Verlag 88/1-2(2006-09-01), 181-206 0930-0708 88:1-2<181 2006 88 710 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer