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| Titel |
Subduction of Indian continent beneath southern Tibet in the latest Eocene (∼ 35 Ma): insights from the Quguosha gabbros in southern Lhasa block |
| VerfasserIn |
Lin Ma, Qiang Wang, Zheng-Xiang Li, Derek Wyman, Zi-Qi Jiang |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126095
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| Publikation (Nr.) |
 EGU/EGU2016-5774.pdf |
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| Zusammenfassung |
| Geophysical data illustrate that the Indian continental lithosphere has northward subducted
beneath the Tibet Plateau. However, when the Indian continental lithosphere started to
subduct remain unclear. Here we report new results from the Quguosha gabbros of
southern Lhasa block, southern Tibet. LA-ICP-MS zircon U–Pb dating of two samples
gives a ca. 35 Ma formation age (i.e., the latest Eocene) for the Quguosha gabbros,
which are within a magmatism gap of the Lhasa block. The Quguosha gabbros
samples exhibit Sr–Nd isotopic compositions ([87Sr/86Sr]initial = 0.7056–0.7058
and ɛNd(t) = -2.2 – -3.6) different from those of the Jurassic–Eocene magmatic
rocks with depleted Sr–Nd isotopic characteristics, but somewhat similar to those of
Oligocene–Miocene K–rich magmatic rocks with enriched Sr–Nd isotopic characteristics. We
interpret the Quguosha mafic magmas to have been generated by partial melting of
lithospheric mantle metasomatized by subducted continental sediments, which entered
continental subduction channel(s) and then probably accreted or underplated into the
overlying mantle during the northward subduction of the Indian continent. Our
data also suggest that the Indian continental crust has started to be underthrusted
beneath the mantle lithosphere of the southern Lhasa sub-block by at least ca. 35 Ma. |
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