tübinger geowissenschaftliche arbeiten (tga) - TOBIAS-lib ...

More documents

Recommendations

Info

66 The Permo-Triassic volcano-siliciclastic sediments of the Lake Karakul area constitute the Karakul-Mazar/Sonpan-Ganze accretionary wedge rocks. The Late Triassic/Jurassic Karakul lake batholith is stitching together the Kunlun arcs and are correlated to the western Kunlun (Akarz mountain pluton, (?)Sailiyak magmatic belt) and to the western Badakshan, western Hindu Kush, and Feroz Koh regions (e.g. at Salang pass). South of the northern Pamirs/Kunlun, the cryptic Tanymas/Jinsha suture evidence mainly Triassic southward subduction of the Karakul-Mazar/Sonpan-Ganze ocean beneath the Central Pamirs/Qiangtang block. The basement antiforms of the Central Pamirs and Qiangtang, formerly interpreted to be of Precambrian age, are mainly composed of exhumed medium to high-grade metamorphic Tanymas/Jinsha ocean floor and Triassic/Jurassic basin associations. Eventually, in the Safed Khers related basement domes are exposed and the Band-e Bayan and Farah Rod can be correlated with the Central Pamirs and Qiangtang. The southern margin of the Central Pamirs and the Rushan Pshart zone are intruded by several granitoids of diverse composition and with distinct age groups or age components from 250-200 Ma and 200-150 Ma. The first group is attributed to the southward subduction along the Jinsha suture, whereas the latter group represent the Rushan Pshart arc, which developed by Jurassic northward subduction of oceanic lithosphere of the Rushan Pshart basin. A similar zone is found along the Bangong- Nujiang zone in Central Tibet. As in the Pamirs, the closure of scattered oceanized basins along the Rushan Pshart and Bangong-Nujiang zones led to the collision of the Central Pamirs/ Qiangtang block with the SE Pamirs/Lhasa blocks. South of the SE Pamirs/Lhasa terranes, a new active margin established. Probably upper Lower Cretaceous (~120 Ma) collision of the Karakorum with the eastern Hindu Kush and SE Pamirs along the Tirich Mir/Kilik (?)suture and Late Cretaceous (~80 Ma) collision of the Kohistan/Ladakh arc with the Karakorum along the Shyok suture caused bimodal intrusion of granitoids as far as to the northern Central Pamirs. This study suggests a relatively simple first-order crustal structure for the Pamirs and Tibet. From the Kunlun arc in the north to the southern Qiangtang block in the south, the Pamirs and Tibet have a dominantly (meta)sedimentary crust, characterised by the Karakul-Mazar/Sonpan-Ganze accretionary wedge rocks. The crust south of the southern Qiangtang block is likely of granodioritic composition, reflecting long-lived subduction, arc formation and Cretaceous-Cenozoic underthrusting of arc segments beneath the Qiangtang block.
4 Cenozoic exhumation history of the southernmost Tien Shan and eastern Pamirs 4.1 Introduction In the previous chapter it was suggested that the Pamirs assembled by orogenic processes from Late Palaeozoic to Mesozoic times, i.e. by the development of successively southward-stepping Andean-type plate margins. In contrast, the Recent Pamirs mountain range is a result of the Tertiary India-Asia collision, which brought the Pamirs into an intra-continental plate position. So far, no comprehensive study exists about the Tertiary thermal evolution of the Pamirs. Regional studies define an important Tertiary tectonothermal event in the south-western Pamirs (Hubbard et al. 1999) and eastern Central Pamirs (Ratschbacher & Schwab 1999, Schwab et al. 1999, 2000), but it remains an open question where exactly Cenozoic deformation and related exhumation is located in the Pamirs and when exhumation started. Several Tertiary intramontane basins along the southernmost Tien Shan, the margins of the external Pamirs, and in the Central Pamirs are indicative for active erosion during the Tertiary. 67
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 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 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
Page 128: 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
Page 150 and 151:
XX Appendix B Plate B1 Cathodolumin
Page 152 and 153:
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
Page 184:
LIV Tab. C7 Apatite and zircon fiss
show all

tübinger geowissenschaftliche arbeiten (tga) - TOBIAS-lib ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?