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22 Northern Pamirs A model from Burtman & Molnar (1993) comprises three east-west trending suture zones in the Pamirs defining the margins of three individual terranes: the Northern, Central, and Southern Pamirs (Fig. 3.1). The following description of the units and the data presentation follows this division. Deformation in these main tectonic belts of the Pamirs occurred in the Late Palaeozoic, Late Mesozoic and Cenozoic (Burtman & Molnar 1993). The Northern Pamirs are composed of different tectonic subunits: the northernmost external part of the Pamirs comprises imbricated Palaeozoic metasedimentary and metavolcanic rocks, as well as Mesozoic and Cenozoic sedimentary strata. Along this northern orogenic front the Pamirs as a whole are translated northward with respect to Eurasia. This is indicated by seismic activity at the active Main Pamir fault, the northward propagation of thrusting and the progressive annihilation of the intramontane Alay basin (Strecker et al. 1995b). A micro-continent with Proterozoic basement is documented in the north-western part of the northern Pamirs. On the northern rim, this basement is locally overlain from an Early to Middle Carboniferous
igneous and sedimentary rock sequence deposited in an oceanic environment (Geological map of Tadzhik SSR 1983, Ruzhentsev and Shvol’mann 1982). This cover encloses volcanic rocks (Burtman & Molnar 1993), which are unconformably overlain by flysch-greywacke sequences of Middle to Upper Carboniferous and Permian age. All strata were deformed in the latest Palaeozoic, during the closure of the Palaeotethys. The southern subzone consists predominantly of Late Palaeozoic flysch and molasse sediments and a narrow band of Middle to Upper Triassic basaltic andesites belonging to a calc-alkaline series (Burtman & Molnar 1993). These volcanic rocks unconformably overlie the Palaeozoic rocks. In the Lake Karakul area large batholiths of Triassic age are widespread. This area represents a large depression dominantly filled with Quaternary lacustrine and glacial deposits (Strecker et al. 1995b). In the eastern part of the Northern Pamirs, the active Markansu fault in the north and the Aksu-Rangkul fault in the south document dextral strike-slip; intervening is the rift structure of the Karakul area. In the southern part of the Northern Pamirs thrust faults are south vergent. This southern margin of the Northern Pamirs documents the Late Palaeozoic accretion of the Central Pamirs (Burtman & Molnar 1993). Neither the exact closing time of the suture nor an intervening oceanic basin are well constrained. Based on oceanic rock assemblages, the Late Palaeozoic suture can be traced from the southern margin of the Northern Pamirs, where it is called Tanymas suture, into the northern Hindu Kush in Afghanistan, and into the Kunlun in Tibet (Burtman & Molnar 1993). Central Pamirs, Rushan Pshart Zone, and South Pamirs The Late Palaeozoic and Mesozoic history of the Central Pamirs, Rushan Pshart zone (RPZ), and of the South Pamirs (Fig. 1.1 and 3.1) has been much debated. In tectonic and palaeogeographic reconstructions, Karapetov et al. (1975), Shvol´man (1978), Pashkov & Shvol´man (1979) and Shvol´man & Pashkov (1986) interpret the RPZ as a major tectonic suture extending into Afghanistan and Tibet, and marking the consumption of a Permo-Triassic ocean that closed during the Jurassic. In some palaeotectonic reconstructions, the oceanic basin is thought to have been more than 2000 km wide in the Triassic (Sengör 1990). Burtman & Molnar (1993) pointed out that the Khas Rud ophiolite in Afghanistan is likely an equivalent of the RPZ. Late Palaeozoic to Mesozoic sedimentary sequences of the Farah Rud basin in Afghanistan were apparently deposited on a passive continental margin and can be correlated to sequences near the southern edge of the Central Pamirs. The eastward continuation of the Farah Rud and RPZ to Tibet is more problematic: two ophiolite belts are commonly interpreted as Mesozoic sutures in Central Tibet. One lies south of the Kunlun mountains (e.g. Pearce & Deng 1988, Sengör 1984) extending to north-eastern Tibet. The other one is the Banggong suture (e.g. Matte et al. 1992) in western Tibet. Burtman & Molnar (1993) aligned the west Kunlun suture with the RPZ and the Banggong suture with the Shyok suture. The Shyok and Indus-Tsangpo ophiolite belts mark the suture between India and Eurasia and intervening island arcs; in latest Mesozoic the Karakoram, Kohistan and Ladakh were incorporated and in early Cenozoic time India was involved (e.g., Petterson & Windley 1985, Coward et al. 1987). 23
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: Two Palaeozoic sutures divide the C
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 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
Page 124 and 125:
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
Page 132 and 133:
II Appendix A Tab. A1 Sample descri
Page 134 and 135:
IV Tab. A2 continued Pamir frontal
Page 136 and 137:
VI Tab. A2 continued Tertiary exten
Page 138 and 139:
VIII Tab. A3 continued Sample Miner
Page 140 and 141:
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
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XXIV Plate B5 Cathodoluminescence i
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XXVI Tab. C2 Determination of the
Page 158 and 159:
XXVIII
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XXX
Page 162 and 163:
XXXII
Page 164 and 165:
XXXIV
Page 166 and 167:
XXXVI Tab. C5 continued Sample grai
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XXXVIII Tab. C5 continued Sample gr
Page 170 and 171:
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
Page 178 and 179:
XLVIII
Page 182 and 183:
LII
Page 184:
LIV Tab. C7 Apatite and zircon fiss
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