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32 of 26-40 for samples P2, P5, and 96A10b. The other two samples M96A7 and P7 have lower REE concentrations of rock/chondrite in respect to the other samples of this group and have a higher negative Eu-anomaly, most likely due to higher plagioclase fractionation. The chondrite-normalised REE pattern of sample A96S1b shows no Euanomaly and is comparable to the REE pattern of sample 96M9a. The La N/Lu N of the latite-andesite is 13, resembling typical alkaline REE distributions.
3.4 Geochronology 3.4.1 U/Pb isotope dilution, SHRIMP U/Pb and Pb-evaporation zircon ages The results of U/Pb isotope dilution analyses of 50 single zircon fractions from 15 magmatic rock samples are given in Appendix A, Tab. A7. In average 5-10 zircon grains were analysed per fraction. The radiogenic 207 Pb/ 206 Pb evaporation method was conducted on 2 single zircon grains of sample 96M9a (Appendix A, Tab. A8). Appendix A, Tab. A9 shows the isotopic ratios of single zircon SHRIMP analyses performed on zircons of 5 different samples. Concordia diagrams with the U/Pb isotopic data, the histogram of the radiogenic 207 Pb/ 206 Pb ratios obtained by the evaporation method, and weighted mean age diagrams of SHRIMP data are shown in Fig. 3.7. Northern Pamirs/Altyndara valley AD2a: From AD2a, the Altyndara metarhyolite, three zircon fractions were analysed. The zircons show elongated magmatic habitus with longer (fraction F1) and smaller prisms (F3 and F5). The zircons are < 200 �m in size, corners are sometimes rounded and many grains are broken. Most grains show magmatic zonation (cathodoluminescence images, Appendix B, plate B1), but some are also metamict with diffuse internal parts. In some cases embayments can be seen at the outer margin but also at margins of cores. Frequently sector zoning is observable. Based on the external morphology of the zircons, the grains plot in the calc-alkaline and sub-alkaline fields of a Pupin diagram (Pupin 1980). Two data points are concordant at 329 � 5 Ma, which is interpreted as crystallisation age, and one data point plots above the concordia (Fig. 3.7a). AD6c: An andesite-dacite sample from the metavolcanic unit of the Altyndara valley has only few and small (80-150 �m) zircons and only one fraction (F2) was dated. The U/Pb isotopic ratios were plotted into the same diagram as sample AD2a (Fig. 3.7a), due to its close association within the same Palaeozoic metavolcano-sedimentary succession. Fraction 2 (AD6c) plots slightly below the concordia close to the fractions of sample AD2a, and it is concluded that AD6c has the same late Early Carboniferous age than AD2a. All fractions from both samples have identical 207 Pb/ 235 U ages. In cathodoluminescence images (Appendix B, plate B1) these zircons reveal magmatic zoning with low-angle truncations dominating over high-angle truncations. In comparison with sample AD2a, AD6c zircons have only small or no cores. In some zircons magmatic or fluid resorption is visible. Northern Pamirs/Karakul lake P26: From the P26 granite three zircon fractions were analysed with the U/Pb isotope dilution method (Fig. 3.7b). This sample yielded ambiguous results. Data are neither concordant nor colinear. One fraction (2b) plots above the concordia, possibly suggesting an analytical problem due to U loss during wet-chemical treatment. Embedding of more common lead into the lattice during zircon alteration could be an alternative explanation. A minimum U/Pb age of about 216 ± 2.0 Ma is suggested. To constrain the age of this sample more precise SHRIMP analyses were performed on 10 single zircon grains. The weighted mean 206 Pb/ 238 U age is 227.0 ± 4.1 Ma. Most likely 33
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Institut für Geowissenschaften (IF
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Key words: Tien Shan, Pamirs, Tibet
Page 6 and 7: * Nr. 22 MESCHEDE, M. (1994): Tecto
Page 8 and 9: * Nr. 55 REINECKER, J. (2000): Stre
Page 13 and 14: The amalgamation of the Pamirs and
Page 15: Wer aber je auf Asiens Erdboden sch
Page 20 and 21: viii (1971). Black lines with arrow
Page 22 and 23: x sample locations and age distribu
Page 24 and 25: xii Swedish expeditions followed. I
Page 26 and 27: 2 postulated that the Safed Khers a
Page 28 and 29: 4 Zusammenfassung Die paläozoische
Page 30 and 31: 6 (d) Oberkreide Spaltspurenalter w
Page 32 and 33: 8 deformation propagate from the pl
Page 34 and 35: 10 source terrains, changes in the
Page 36 and 37: 12 Geochemisches Zentrallabor, Univ
Page 38 and 39: 14 mean UO+/U+ and Pb+/U+ value. Si
Page 40 and 41: 16 apatites and zircons were counte
Page 42 and 43: 18 number of simulation runs and th
Page 45 and 46: Two Palaeozoic sutures divide the C
Page 47 and 48: igneous and sedimentary rock sequen
Page 49 and 50: Triassic and the formation of an is
Page 51 and 52: 27 Lake Karakul The Lake Karakul ar
Page 53: 3.3.2 Major and trace elements Majo
Page 58 and 59: 34 some of the zircons suffered Pb
Page 60 and 61: 36 fractions are situated close to
Page 65: 3.4.2 Rb/Sr dating The Rb/Sr minera
Page 69 and 70: 45 The Cretaceous plutons show mode
Page 72 and 73: 48 Thompson et al. (1984), who see
Page 74 and 75: 50 granites and have Sm-Nd model ag
Page 76 and 77: 52 associations in Afghanistan is f
Page 78 and 79: 54 Kara Kunlun or Mazar accretionar
Page 80 and 81: 56 Early Jurassic low-angle normal
Page 82 and 83: 58 Coward et al. (1988) pointed out
Page 84 and 85: 60 oceanic crust for the consumptio
Page 86 and 87: 62 Palaeogene volcanic rocks of cen
Page 88: 64 3.7 Conclusions Based on new own
Page 91 and 92: 4 Cenozoic exhumation history of th
Page 93 and 94: Southern Tien Shan One Permian gran
Page 97 and 98: Thermal modelling The results of th
Page 99 and 100: amphibole, white mica, and biotite
Page 101 and 102: the zircon PAZ. The apparent apatit
Page 103 and 104: elt likely operated as an out-of-se
Page 105: ages from gneissic rocks within the
Page 108 and 109:
84 south to 18 Ma in the north; the
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86 Cretaceous plutons that intrude
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88 6 References Allègre C.J., Cout
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90 House, scale 1:2 000 000. Chen F
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92 Karakorum (Sinkiang, China); the
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94 Hurford A.J. and Hammerschmidt K
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96 without double spiking. Geochimi
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98 Geological Society of America, 2
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100 Zamoruyev A., 1995a. Neotectoni
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102 Ann. Rev. of Earth and Planetar
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104 this work, especially all membe
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II Appendix A Tab. A1 Sample descri
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IV Tab. A2 continued Pamir frontal
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VI Tab. A2 continued Tertiary exten
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VIII Tab. A3 continued Sample Miner
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X Tab. A6 Rb/Sr and Sm/Nd isotopic
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XII Tab. A7 continued Apparent ages
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XIV Tab. A9 U/Pb isotopic ratios fr
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XVI Tab. A9 continued 207 Pb/ 206 P
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XVIII Tab. A9 continued 207 Pb/ 206
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XX Appendix B Plate B1 Cathodolumin
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XXII Plate B3 Cathodoluminescence i
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XXIV Plate B5 Cathodoluminescence i
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XXVI Tab. C2 Determination of the
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XXVIII
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XXX
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XXXII
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XXXIV
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XXXVI Tab. C5 continued Sample grai
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XXXVIII Tab. C5 continued Sample gr
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XL Tab. C5 continued Sample grain-n
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XLII Tab. C5 continued Sample grain
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XLIV
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XLVI Tab. C6 Zircon fission track a
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XLVIII
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LII
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LIV Tab. C7 Apatite and zircon fiss
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