Early Palaeozoic deep subduction of continental crust in the Kyrgyz North Tianshan: Evidence from Lu-Hf garnet geochronology and petrology of mafic dikes.
Rojas-Agramonte Y, Herwartz D, Garcia-Casco A, Kroener A, Alexeiev DV, Klemd R, Buhre S, Barth M (2013)
Publication Type: Journal article
Publication year: 2013
Journal
Publisher: Springer Verlag (Germany)
Book Volume: 166
Pages Range: 525-543
DOI: 10.1007/s00410-013-0889-y
Abstract
High-pressure and ultrahigh-pressure (UHP) eclogite-bearing metamorphic assemblages in the North Tianshan of Kyrgyzstan are known from the Aktyuz and Makbal areas, where eclogites and garnet amphibolites are associated with continental rocks such as granitoid gneisses in Aktyuz and shallow-water clastic (passive margin?) metasediments in Makbal. We present the first Lu-Hf isotope data for an eclogite and two garnet amphibolite samples from the two metamorphic terranes which, combined with petrological analysis, tightly constrain the age of high-pressure metamorphism in the Kyrgyz North Tianshan. A five-point isochron for an Aktyuz eclogite sample provides a Lu-Hf age of 474.3 ± 2.2 Ma, and a four-point isochron on a Makbal sample corresponds to 470.1 ± 2.5 Ma. A prograde, subduction-related path is inferred for both samples with peak P-T conditions ranging from 1.4 to 1.6 GPa and 610-620 °C. A further Makbal sample provided a significantly older Lu-Hf age of 486 ± 5.4 Ma, most likely due to late alteration in the sample (late addition of unradiogenic Hf). We conclude that garnet growth in all three samples occurred around ca. 474 Ma and that these rocks likely experienced UHP metamorphism contemporaneously. Our results support previous geochronological evidence for an Early Ordovician collision belt in the North Tianshan and allow refinement of a tectonic model involving subduction of thinned continental crust to considerable depth along the margin of a small microcontinent. © 2013 Springer-Verlag Berlin Heidelberg.
Authors with CRIS profile
Involved external institutions
Chinese Academy of Geological Sciences (CAGS) / 中国地质科学院
China (CN)
Russian Academy of Sciences / Росси́йская акаде́мия нау́к (RAS)
Russian Federation (RU)
Universidad de Granada
Spain (ES)
Rheinische Friedrich-Wilhelms-Universität Bonn
Germany (DE)
China (CN)
Russian Academy of Sciences / Росси́йская акаде́мия нау́к (RAS)
Russian Federation (RU)
Universidad de Granada
Spain (ES)
Rheinische Friedrich-Wilhelms-Universität Bonn
Germany (DE)
How to cite
APA:
Rojas-Agramonte, Y., Herwartz, D., Garcia-Casco, A., Kroener, A., Alexeiev, D.V., Klemd, R.,... Barth, M. (2013). Early Palaeozoic deep subduction of continental crust in the Kyrgyz North Tianshan: Evidence from Lu-Hf garnet geochronology and petrology of mafic dikes. Contributions To Mineralogy and Petrology, 166, 525-543. https://doi.org/10.1007/s00410-013-0889-y
MLA:
Rojas-Agramonte, Yamirka, et al. "Early Palaeozoic deep subduction of continental crust in the Kyrgyz North Tianshan: Evidence from Lu-Hf garnet geochronology and petrology of mafic dikes." Contributions To Mineralogy and Petrology 166 (2013): 525-543.
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