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| Titel |
Tectonic evolution and high-pressure rock exhumation in the Qiangtang terrane, central Tibet |
| VerfasserIn |
Z. Zhao, P. D. Bons, G. Wang, A. Soesoo, Y. Liu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 2 ; Nr. 6, no. 2 (2015-04-30), S.457-473 |
| Datensatznummer |
250115444
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| Publikation (Nr.) |
 copernicus.org/se-6-457-2015.pdf |
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| Zusammenfassung |
| Conflicting interpretations of the > 500 km long, east–west-trending Qiangtang metamorphic belt have led to very different and
contradicting models for the Permo–Triassic tectonic evolution of central
Tibet. We define two metamorphic events, one that only affected
pre-Ordovician basement rocks and one subduction-related Triassic
high-pressure metamorphism event. Detailed mapping and structural analysis
allowed us to define three main units that were juxtaposed due to collision
of the north and south Qiangtang terranes after closure of the
Ordovician–Triassic ocean that separated them. The base is formed by the
Precambrian–Carboniferous basement, followed by non-metamorphic ophiolitic
mélange containing mafic rocks that range in age from the Ordovician to
Middle Triassic. The top of the sequence is formed by strongly deformed
sedimentary mélange that contains up to > 10 km size rafts of
both unmetamorphosed Permian sediments and high-pressure blueschists. We
propose that the high-pressure rocks were exhumed from underneath the south
Qiangtang terrane in an extensional setting caused by the pull of the
northward subducting slab of the Shuanghu–Tethys. High-pressure rocks,
sedimentary mélange and margin sediments were thrust on top of the
ophiolitic mélange that was scraped off the subducting plate. Both units
were subsequently thrust on top of the south Qiantang terrane continental
basement. Onset of Late Triassic sedimentation marked the end of the
amalgamation of both Qiangtang terranes and the beginning of spreading
between Qiantang and north Lhasa to the south, leading to the deposition of
thick flysch deposits in the Jurassic. |
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