caa a22 4500 467890080 CHVBK 20180406152746.0 cr unu---uuuuu 170328e20060901xx s 000 0 eng 10.1007/s00710-006-0149-1 doi (NATIONALLICENCE)springer-10.1007/s00710-006-0149-1 Geochronology and tectonic significance of Middle Proterozoic granitic orthogneiss, North Qaidam HP/UHP terrane, Western China [Elektronische Daten] [C. G. Mattinson, J. L. Wooden, J. G. Liou, D. K. Bird, C. L. Wu] Summary: Amphibolite-facies para- and orthogneisses near Dulan, in the southeast part of the North Qaidam terrane, enclose minor ultra-high pressure (UHP) eclogite and peridotite. Field relations and coesite inclusions in zircons from paragneiss suggest that felsic, mafic, and ultramafic rocks all experienced UHP metamorphism and a common amphibolite-facies retrogression. Ion microprobe U-Pb and REE analyses of zircons from two granitic orthogneisses indicate magmatic crystallization at 927 ± Ma and 921 ± 7 Ma. Zircon rims in one of these samples yield younger ages (397-618 Ma) compatible with partial zircon recrystallization during in-situ Ordovician-Silurian eclogite-facies metamorphism previously determined from eclogite and paragneiss in this area. The similarity between a 2496 ± 18 Ma xenocrystic core and 2.4-2.5 Ga zircon cores in the surrounding paragneiss suggests that the granites intruded the sediments or that the granite is a melt of the older basement which supplied detritus to the sediments. The magmatic ages of the granitic orthogneisses are similar to 920-930 Ma ages of (meta)granitoids described further northwest in the North Qaidam terrane and its correlative west of the Altyn Tagh fault, suggesting that these areas formed a coherent block prior to widespread Mid Proterozoic granitic magmatism. Springer-Verlag, 2006 Mattinson C. G. Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, U.S.A. aut Wooden J. L. United States Geological Survey, Menlo Park, CA, U.S.A. aut Liou J. G. Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, U.S.A. aut Bird D. K. Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, U.S.A. aut Wu C. L. Chinese Academy of Geological Sciences, Institute of Geology, Beijing, China aut Mineralogy and Petrology Springer-Verlag 88/1-2(2006-09-01), 227-241 0930-0708 88:1-2<227 2006 88 710 https://doi.org/10.1007/s00710-006-0149-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00710-006-0149-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mattinson C. G. Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, U.S.A aut NATIONALLICENCE 700 1- Wooden J. L. United States Geological Survey, Menlo Park, CA, U.S.A aut NATIONALLICENCE 700 1- Liou J. G. Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, U.S.A aut NATIONALLICENCE 700 1- Bird D. K. Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, U.S.A aut NATIONALLICENCE 700 1- Wu C. L. Chinese Academy of Geological Sciences, Institute of Geology, Beijing, China aut NATIONALLICENCE 773 0- Mineralogy and Petrology Springer-Verlag 88/1-2(2006-09-01), 227-241 0930-0708 88:1-2<227 2006 88 710 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer