Tectonic Implications of U-Pb Zircon Ages of the Himalayan Orogenic Belt in Nepal

American Association for the Advancement of Science (AAAS) - Tập 288 Số 5465 - Trang 497-499 - 2000
Peter G. DeCelles1, George E. Gehrels1, Jay Quade1, B. N. LaReau1, Matthew S. Spurlin1
1Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA

Tóm tắt

Metasedimentary rocks of the Greater Himalaya are traditionally viewed as Indian shield basement that has been thrust southward onto Lesser Himalayan sedimentary rocks during the Cenozoic collision of India and Eurasia. Ages determined from radioactive decay of uranium to lead in zircon grains from Nepal suggest that Greater Himalayan protoliths were shed from the northern end of the East African orogen during the late Proterozoic pan-African orogenic event. These rocks were accreted onto northern Gondwana and intruded by crustal melts during Cambrian-Ordovician time. Our data suggest that the Main Central thrust may have a large amount of pre-Tertiary displacement, that structural restorations placing Greater Himalayan rocks below Lesser Himalayan rocks at the onset of Cenozoic orogenesis are flawed, and that some metamorphism of Greater Himalayan rocks may have occurred during early Paleozoic time.

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Tài liệu tham khảo

A. Gansser Geology of the Himalayas (Wiley-Interscience New York 1964).

10.1098/rsta.1988.0135

10.1016/0191-8141(86)90037-4

Gaetani M., Garzanti E., Am. Assn. Petrol. Geol. Bull. 75, 1427 (1991).

10.1016/0037-0738(93)90042-4

10.1029/TC007i003p00583

10.1130/0091-7613(1999)027<0151:BFITCO>2.3.CO;2

10.1111/j.1525-1314.1989.tb00573.x

10.1029/92TC00213

10.1029/96TC01791

10.1016/0012-821X(83)90115-2

LeFort P., Debon F., Pêcher A., Sonet J., Vidal P., Sci. Terre Mem. 47, 191 (1986).

Trivedi J. R., Gopalan K., Valdiya K. S., J. Geol. Soc. India 25, 641 (1984).

10.1029/JB086iB11p10545

10.1007/BF01765903

10.1016/0012-821X(86)90130-5

10.1007/BF00375529

France-Lanord C., LeFort P., Trans. R. Soc. Edinburgh 99, 183 (1988).

Frank W., Fuchs G., Jahrb. Geol. Bundesanst. 18, 103 (1970).

10.1016/0037-0738(74)90027-X

10.1144/gsjgs.137.1.0001

K. S. Valdiya Geology of the Kumaon Lesser Himalaya (Wadia Institute of Himalayan Geology Dehra Dun India 1980).

H. Sakai Mem. Fac. Sci. Kyushu Univ. Ser. D 25 (no. 1) 27 (1983).

___ Mem. Fac. Sci. Kyushu Univ. Ser. D 25 (no. 3) 337 (1985).

10.1029/98TC02598

10.1130/0016-7606(1996)108<0904:ICOTAA>2.3.CO;2

U-Pb ages were determined from 41 samples each of which was collected from a single outcrop (Fig. 1). The zircons were extracted in the field using a hand-held crusher and gold pan and were processed as described [

10.1139/e91-114

]. Analyses were conducted on abraded single zircon crystals by means of isotope-dilution thermal ionization mass spectrometry. The 445 detrital zircon ages shown in Fig. 2 are 207 Pb*/ 206 Pb* ages most of which are concordant to <20% discordant. The ages of plutons are based on upper concordia intercepts. For analytical data and sample descriptions see Science Online at www.sciencemag.org/feature/data/1047462.shl.

S. M. Naqvi and J. J. W. Rogers Precambrian Geology of India (Clarendon New York 1987).

10.1130/0016-7606(1998)110<0002:NFBDEU>2.3.CO;2

Bouquillon A., France-Lanord C., Michard A., Tiercelin J.-J., Proc. ODP Sci. Res. 116, 43 (1990).

10.1016/0012-821X(96)00091-X

10.1130/0091-7613(1999)027<0585:LCITWH>2.3.CO;2

D. M. Robinson et al. Geol. Soc. Am. Abstr. Prog. A96 (1999).

C. R. Scotese PALEOMAP Paleogeographic Atlas PALEOMAP Progress Report 90 (Department of Geology Univ. of Texas Arlington TX 1997).

R. Unrug Rodinia to Gondwana: The Geodynamic Map of Gondwana Supercontinent Assembly (Bureau de Recherches Géologiques et Minières Orleans France 1996).

10.1130/0016-7606(1997)109<0016:ONPGAT>2.3.CO;2

K. R. Pogue M. D. Hylland R. S. Yeats W. U. Khattak A. Hussain Geol. Soc. Am. Spec. Pap. 328 (1999) p. 257.

J. A. DiPietro et al. Geol. Soc. London Spec. Pub. 74 (1993) p. 207.

10.1146/annurev.ea.22.050194.001535

10.1126/science.252.5011.1409

10.1016/0037-0738(86)90032-1

R. M. Manickavasagam A. K. Jain S. Singh A. Asokan Geol. Soc. Am. Spec. Pap. 328 (1999) p. 179.

A. M. C. Sengor and B. A. Natal'in in The Tectonic Evolution of Asia A. Yin and T. M. Harrison Eds. (Cambridge Univ. Press Cambridge 1996) pp. 486–640.

A. Yin and S. A. Nie in The Tectonic Evolution of Asia A. Yin and T. M. Harrison Eds. (Cambridge Univ. Press Cambridge 1996) pp. 442–485.

10.1029/94JB00932

10.1126/science.255.5052.1663

10.1029/98TC01314

10.1139/e86-111

10.1016/0040-1951(83)90258-5

10.1029/93TC00916

Supported by NSF grants EAR-9418207 and EAR-9725607. We thank T. P. Ojha B. N. Upreti D. M. Robinson C. N. Garzione P. Kapp and P. Kaminski for assistance in the field and two anonymous reviewers for useful commentary.

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American Association for the Advancement of Science (AAAS)

Tập 288 Số 5465

497-499

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