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Yadong to Golmud Transect Qinghai - Tibet Plateau, China

Yadong to Golmud Transect Qinghai - Tibet Plateau, China

Wu Gongjian (Editor), Xiao Xuchang (Editor), Li Tingdong (Editor)

ISBN: 978-1-118-66785-9

Mar 2013, American Geophysical Union

32 pages

Select type: O-Book

Description

Published by the American Geophysical Union as part of the Global Geoscience Transects Series, Volume 3.

The Global Geoscience Transects Project (GGT) is an ambitious international effort that draws together geoscientists in a variety of disciplines to produce the best possible portrayal of the composition and structure of the Earth's crust. Since its inception in 1985, GGT has encouraged geoscientists in all countries of the world to compile cross sections of the Earth up to a few thousands of kilometers in length and drawn to the base of the crust using all available geological, geophysical, and geochemical information. Transects are drawn to common scales and formats so that the Earth's crust in different parts of the world can be directly compared

GGT was conceived by the Inter-Union Commission on the Lithosphere (ICL), a "child" of the International Union of Geological Sciences and the International Union of Geodesy and Geophysics (IUGG), at the IASPEI conference in Tokyo in August 1985. Project coordinators James W. H. Monger and Hans-Jurgen Götze organized a multidisciplinary, multinational committee that coordinated the global project. Meeting at the IUGG XIX General Assembly in Vancouver in August 1987, the committee developed preliminary guidelines for transect compilations, following suggestions from transect compilers. Proposals for transects were solicited from ICL national committees, government geoscience agencies, universities, and scientists. A total of 140 proposals were received from Africa (41), South America (30), China (18),USSR (12), USA (12), Europe (12), Australia and New Zealand (11), India (3), and Southeast Asia (1).

PREFACE 5

I COMPONENTS OF THE YADONG-GOLMUD TRANSECT DISPLAY 6

Index map showing location of Chinese transects 6

Index map showing location of transect relative to belts and terranes 6

Geological map 6

Geological cross-section 6

Time-space and tectonic kindreds diagrams 6

Map of apparent polar wander paths 6

Gravity Map 7

(a) Gravity 7

(b) Line of seismic sounding profiles 8

(c) Heat flow data 8

(d) Earthquakes 8

Magnetic map 8

Geophysical interpretations 8

(a) Seismic profiles 8

(b) Depth of Moho 8

(c) Magnetotelluric sounding-resistivity distribution. 9

(d) Density distribution 9

Interpretative cross-section 9

(a) Structure of the crust 10

(b) Boundaries of terranes and other important faults 10

(c) Magmatic rocks 10

Tectonic evolution of the Qinghai-Tibet Plateau 10

Geodynamic diagram of the Qinghai-Tibet Plateau 10

I1 COMPREHENSIVE INTERPRETATION OF THE TRANSECT 10

1 The Qinghai-Tibet Plateau. an amalgam of terranes 10

(a) Belts and terranes 10

(b) Evolutionary history of terranes 10

1) North Kunlun terrane 10

2) South Kunlun terrane 11

3) Bayan Har terrane 11

4) Qiangtang terrane 12

5) Lhasa terrane 12

6) GyangzC terrane 13

(c) Relative movements of terranes 14

1) Paleomagnetic studies 15

2) Biogeographic provinces; the northern boundary of Gondwana 15

(d) Application of geophysical methods to subdivision of terranes 17

1) Seismic velocity structure 17

2) Magnetotelluric sounding 17

3) Gravity and magnetic characteristics 17

2 Structure and composition of the lithosphere 19

(a) Subdivision of layers in the lithosphere 19

(b) Magnetic interface in the lithosphere 20

(c) Crustal and lithospheric thickness 20

(d) Thermal structure of the lithosphere 20

(e) Isostatic state of the lithosphere 20

(f) Earthquakes 21

(g) Composition of the lithosphere in the transect corridor 21

III CRUSTAL COLLISION AND THE MECHANISM OF SHORTENING. THICKENING AND UPL LFT 22

1 Tectonic evolution of the lithosphere during and after collision 23

(a) The first stage of collision: thrust faulting and crustal stacking 23

(b) The second stage of collision: dominated by folding 23

(c) The third stage of collision: dominated by strike-slip faults 24

(d) The post-collision stage: characterized by activity of fault blocks 24

2 Mechanism of uplift 24

(a) Mechanical mechanism 25

(b) Isostasy 25

(c) Thermal processes 26

(d) Magmatism 27

(e) Crustal rebound caused by Quaternary deglaciation 27

IV CONCLUSIONS AND PROBLEMS 27

1 Conclusions 27

2 Problems 28

(a) Boundary between lithosphere and asthenosphere 28

(b) Driving forces 29

References 30