Carbonated Inheritance in the Eastern Tibetan Lithospheric Mantle: Petrological Evidences and Geodynamic Implications
Result description
The timing and mechanism of formation of the Tibet Plateau remain elusive, and even the present‐day structure of the Tibetan lithosphere is hardly resolved, due to conflicting interpretations of the geophysical data. We show here that significant advances in our understanding of this orogeny could be achieved through a better assessment of the composition and rheological properties of the deepest parts of the Tibetan lithosphere, leading in particular to a reinterpretation of the global tomographic cross sections. We report mantle phlogopite xenocrysts and carbonate‐bearing ultramafic cumulates preserved in Eocene potassic rocks from the Eastern Qiangtang terrane, which provide evidence that the lithospheric mantle in Central Tibet was enriched in H urn:x-wiley:ggge:media:ggge22135:ggge22135-math-0001O and CO urn:x-wiley:ggge:media:ggge22135:ggge22135-math-0002 prior to the India‐Asia collision. Rheological calculations and numerical modeling suggest that (1) such metasomatized mantle would have been significantly weaker than a normal mantle but buoyant enough to prevent its sinking into the deep mantle; (2) the slow seismic anomalies beneath Central Tibet may image a weakened lithosphere of normal thickness rather than a lithosphere thinned and heated by the convective removal of its lower part; and (3) melting of such soft and fusible metasomatized mantle would have been possible during intracontinental subduction, supporting a subduction origin for the studied Eocene potassic magmatism. These results demonstrate that the inheritance a soft and buoyant precollisional Tibetan lithosphere may have conditioned the growth and the present‐day structure of the Tibet Plateau.
Keywords
TibetPlateau carbonatemetasomatism mantlerheology tomography Qiangtang collisionalsubduction
The result's identifiers
Result code in IS VaVaI
Result on the web
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GC008495
DOI - Digital Object Identifier
Alternative languages
Result language
angličtina
Original language name
Carbonated Inheritance in the Eastern Tibetan Lithospheric Mantle: Petrological Evidences and Geodynamic Implications
Original language description
The timing and mechanism of formation of the Tibet Plateau remain elusive, and even the present‐day structure of the Tibetan lithosphere is hardly resolved, due to conflicting interpretations of the geophysical data. We show here that significant advances in our understanding of this orogeny could be achieved through a better assessment of the composition and rheological properties of the deepest parts of the Tibetan lithosphere, leading in particular to a reinterpretation of the global tomographic cross sections. We report mantle phlogopite xenocrysts and carbonate‐bearing ultramafic cumulates preserved in Eocene potassic rocks from the Eastern Qiangtang terrane, which provide evidence that the lithospheric mantle in Central Tibet was enriched in H urn:x-wiley:ggge:media:ggge22135:ggge22135-math-0001O and CO urn:x-wiley:ggge:media:ggge22135:ggge22135-math-0002 prior to the India‐Asia collision. Rheological calculations and numerical modeling suggest that (1) such metasomatized mantle would have been significantly weaker than a normal mantle but buoyant enough to prevent its sinking into the deep mantle; (2) the slow seismic anomalies beneath Central Tibet may image a weakened lithosphere of normal thickness rather than a lithosphere thinned and heated by the convective removal of its lower part; and (3) melting of such soft and fusible metasomatized mantle would have been possible during intracontinental subduction, supporting a subduction origin for the studied Eocene potassic magmatism. These results demonstrate that the inheritance a soft and buoyant precollisional Tibetan lithosphere may have conditioned the growth and the present‐day structure of the Tibet Plateau.
Czech name
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Czech description
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Classification
Type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10505 - Geology
Result continuities
Project
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2020
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Geochemistry Geophysics Geosystems
ISSN
1525-2027
e-ISSN
—
Volume of the periodical
21
Issue of the periodical within the volume
2 : e2019GC008495
Country of publishing house
US - UNITED STATES
Number of pages
22
Pages from-to
nestránkováno
UT code for WoS article
000534478000001
EID of the result in the Scopus database
2-s2.0-85080027978
Basic information
Result type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
OECD FORD
Geology
Year of implementation
2020