Kinematics, topography, shortening, and extrusion in the India‐Eurasia collision

Tectonics - Tập 11 Số 6 - Trang 1085-1098 - 1992
Xavier Le Pichon1, Marc Fournier1, Laurent Jolivet2
1Laboratoire de Géologie
2Institut des Sciences de la Terre d'Orléans

Tóm tắt

We examine the problem of partitioning between shortening and extrusion in the India‐Asia collision since 45 Ma. We compute the amount of shortening expected from the kinematics of India's motion with respect to Eurasia, using the reconstruction at collision time to put bounds on the possible amounts of surface loss within Greater India and within Eurasia. We then compute the amounts of surface loss corresponding to the thickened crust of Tibet and of the Himalayas, assuming conservation of continental crust. The spatial distribution of the topography reveals a large systematic deficit of crustal thickening distributed rather uniformly west of the eastern syntaxis but an excess of shortening east of it. This distribution indicates an important eastward crustal mass transfer. However, the excess mass east of the eastern syntaxis does not account for more than one third to one half of the deficit west of the eastern syntaxis. The deficit may be accounted either by loss of lower crust into the mantle, for example through massive eclogitization, or by lateral extrusion of nonthickened crust. A mass budget of the crust of the Himalayas indicates that lower crust has not been conserved there, but the deficit is so large that local loss in the mantle is unlikely to be the unique cause of the deficit. Alternatively, following Zhao and Morgan [1985], lower crust may have been transferred below the Tibetan crust. We conclude that a combination of possible transfer of lower crust to the mantle by eclogitization and lateral extrusion has to account for a minimum of one third and a maximum of one half of the total amount of shortening between India and Asia since 45 Ma. This conclusion leaves open the possibility that the partitioning between extrusion and loss of lower crust into the mantle on the one hand and shortening on the other hand has significantly changed during the 45 m.y. history of the collision.

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Tài liệu tham khảo

10.1029/JB089iB12p10311

10.1029/JB091iB14p13803

10.1029/JB094iB03p02787

10.1029/JB093iB10p11791

10.1029/90JB01916

10.1029/JB083iB10p04975

10.1029/91JB00370

10.1144/gsjgs.143.6.0857

10.1038/323501a0

Chen Y., 1991, Cretaceous paleomagnetic results from Western Tibet and tectonic implications (abstract), Eos Trans. AGU, 72, 103

10.1130/0091-7613(1990)018<0354:ERUITH>2.3.CO;2

10.1144/gsjgs.144.3.0377

10.1130/0091-7613(1991)019<1097:PGMATB>2.3.CO;2

10.1111/j.1365-246X.1990.tb06579.x

10.1098/rsta.1988.0135

Dewey J. F., 1989, Tectonic evolution of the India‐Eurasia collision zone, Eclogae Geol. Helv., 82, 717

England P., 1986, Finite strain calculations of continental deformation,.2, Comparison with the India‐Asia collisions zone, J. Geophys. Res., 91, 3664, 10.1029/JB091iB03p03664

10.1126/science.235.4793.1156

Harland W. B., 1982, A Geologic Time Scale

10.1038/307025a0

10.1130/DNAG-GNA-M.45

10.1016/0040-1951(87)90271-X

10.1016/0012-821X(85)90099-8

10.1130/SPE218-p111

10.1038/330519a0

10.1029/JB088iB10p08171

10.1029/TC004i006p00513

10.1016/0040-1951(87)90268-X

Ma X., 1984, The structure and dynamics of the continental lithosphere in north‐northwest China, Ann. Geophys., 2, 611

10.1029/TC006i003p00275

Molnar P., 1987, Inversion of profiles of uplift rates for the geometry of dip‐slip faults at depth, with examples from the Alps and the Himalaya, Ann. Geophys., 5, 663

10.1029/JB089iB07p06203

10.1130/SPE218-p179

10.1126/science.189.4201.419

Patriat P. Reconstitution de l'évolution du système de dorsales de l'Océan Indien par les méthodes de la cinématique des plaques Thèse d'état 308 pp. Univ. Paris 7 Paris 1983.

10.1038/311615a0

10.1016/0040-1951(88)90269-7

10.1029/91JB00897

10.1029/JB094iB10p13755

10.1130/0016-7606(1987)98<678:TCOTAT>2.0.CO;2

10.1016/0264-3707(91)90030-I

10.1038/264319a0

10.1029/JB082i020p02905

10.1029/JB084iB07p03425

10.1144/GSL.SP.1986.019.01.07

10.1111/j.1365-246X.1991.tb03906.x

10.1016/0040-1951(91)90055-W

Veevers J. J., 1979, Sedimentary wedge progradation from transform faulted continental rim : Southern Exmouth Plateau, Western Australia, AAPG Bull, 63, 2088

10.1029/TC004i004p00359

10.1111/j.1365-246X.1991.tb00807.x

10.1016/0264-3707(90)90015-M

10.1016/0040-1951(81)90251-1

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Tectonics

Tập 11 Số 6

1085-1098

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