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36 fractions are situated close to the lower intercept, the Early Cretaceous age is interpreted as formation age of the zircons with older inherited components. This is confirmed by the CL images, which show zircons with large cores. Sometimes in the cores a second, older core is included. The cores are either metamict or have a magmatic zonation. The older core type is well rounded, whereas the younger core generation shows only abrasion at the corners. Some zircons seem to reveal a younger rim. SHRIMP analyses (Fig. 3.7l) of 24 grains aimed to probe the core types and rims (Appendix B, plate B4). Three different core ages have been detected: one spot yielded 2187 � 13 Ma, four spots of rounded metamict cores and one weakly zoned inner grain spot range from 250 to 214 Ma (weighted mean 221 � 24 Ma), and four rounded, metamict (one weakly zone) cores range from 182 to 156 Ma (weighted mean 162 � 18 Ma). The majority of spots probed spectacularly zoned idiomorphic grains with spot ages ranging from 130 to 104 Ma (weighted mean of 17 spots 113 � 3.4 Ma); four spots of idiomorphic, well-zoned grains, and outermost idiomorphic rims of grains with cores yielded even younger ages (94 to 77 Ma, weighted mean 90 � 10 Ma). 96A10b: The sample yielded three zircon fractions for conventional U/Pb dating (Fig. 3.7m). Two of the fractions (F1 and F2) plot on the concordia. As fraction F3 has a very small analytical uncertainty but plots below the concordia, Pb loss can be assumed. This might be also true for fraction F1. No older Pb component seems to be inherited. Only one intercept could be calculated which is interpreted as the crystallisation age at 126 � 50 Ma. A96S1b: Six fractions were selected from this subvolcanic latite-andesite (Fig. 3.7n). All fractions consist of small zircons (~63-80 �m). One half is long prismatic, transparent without inclusions. The other half shows transparent whitish to yellowish tabular zircons. Many zircons are broken. Zircons plot into the field of calc-alkaline and subalkaline magma series in the Pupin-diagram. Two fractions (F6 and F7) plot close but above the concordia and fractions F2 and F3 close but below the concordia. These four fractions are interpreted to approximate the crystallisation age, whereas fraction F8 might include inherited cores. Fraction F5 might have lost Pb. The lower intercept age is 74.2 � 0.7 Ma. Northernmost South Pamirs P2: As only one zircon fraction was analysed, which is discordant, no age interpretation could be made (Fig. 3.7o). SHRIMP analyses on 15 zircons (Fig. 3.7p) reveal ages on well rounded cores (Appendix B, plate B4) of about 1624 Ma, 902 Ma, 417 Ma, 355 Ma, and 196 Ma; one 158 Ma spot is from a nodular inner grain portion. 15 spots from rims and multi-faced, idiomorphic grains range from 126 to 102 Ma with a weighted mean age of 117.9 � 3.7 Ma; one grain is as young as 78 � 5 Ma. P5: The two analysed zircon fractions plot close to the lower discordia interception (Fig. 3.7o). Therefore one could choose a simple model of crystallisation with some minor inheritance. Assuming no subsequent Pb loss, the crystallisation age is 74.5 � 8.8 Ma with Precambrian zircon inheritance (i.e. ~710 Ma). The two fractions of sample P5
plot nearly at the same place in the U/Pb concordia diagram as the fraction from sample P2. Both samples belong to nearby calc-alkaline intrusions in the Murgab valley. Assuming that the weighted mean age of sample P2 is also representative for sample P5, one can conclude from the discordia plot, that both samples (P2 and P5) have inheritance and suffered some Pb loss, as they plot just below the assumed concordia age calculated by the SHRIMP data. 37
Page 1:
Institut für Geowissenschaften (IF
Page 4 and 5:
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 56 and 57: 32 of 26-40 for samples P2, P5, and
Page 58 and 59: 34 some of the zircons suffered Pb
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
Page 110 and 111:
86 Cretaceous plutons that intrude
Page 112 and 113:
88 6 References Allègre C.J., Cout
Page 114 and 115:
90 House, scale 1:2 000 000. Chen F
Page 116 and 117:
92 Karakorum (Sinkiang, China); the
Page 118 and 119:
94 Hurford A.J. and Hammerschmidt K
Page 120 and 121:
96 without double spiking. Geochimi
Page 122 and 123:
98 Geological Society of America, 2
Page 124 and 125:
100 Zamoruyev A., 1995a. Neotectoni
Page 126 and 127:
102 Ann. Rev. of Earth and Planetar
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104 this work, especially all membe
Page 132 and 133:
II Appendix A Tab. A1 Sample descri
Page 134 and 135:
IV Tab. A2 continued Pamir frontal
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VI Tab. A2 continued Tertiary exten
Page 138 and 139:
VIII Tab. A3 continued Sample Miner
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X Tab. A6 Rb/Sr and Sm/Nd isotopic
Page 142 and 143:
XII Tab. A7 continued Apparent ages
Page 144 and 145:
XIV Tab. A9 U/Pb isotopic ratios fr
Page 146 and 147:
XVI Tab. A9 continued 207 Pb/ 206 P
Page 148 and 149:
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
Page 154 and 155:
XXIV Plate B5 Cathodoluminescence i
Page 156 and 157:
XXVI Tab. C2 Determination of the
Page 158 and 159:
XXVIII
Page 160 and 161:
XXX
Page 162 and 163:
XXXII
Page 164 and 165:
XXXIV
Page 166 and 167:
XXXVI Tab. C5 continued Sample grai
Page 168 and 169:
XXXVIII Tab. C5 continued Sample gr
Page 170 and 171:
XL Tab. C5 continued Sample grain-n
Page 172 and 173:
XLII Tab. C5 continued Sample grain
Page 174 and 175:
XLIV
Page 176 and 177:
XLVI Tab. C6 Zircon fission track a
Page 178 and 179:
XLVIII
Page 182 and 183:
LII
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LIV Tab. C7 Apatite and zircon fiss
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