TY - JOUR

T1 - Composition and u–Pb (LA-ICP-MS) isotopic age of zircons from composite dikes of western Sangilen (Tuva-Mongolian orogen)

AU - Tsygankov, A. A.

AU - Burmakina, G. N.

AU - Yakovlev, V. A.

AU - Khubanov, V. B.

AU - Vladimirov, V. G.

AU - Karmysheva, I.

AU - Buyantuev, M. D.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Composite dikes (mingling dikes) of Western Sangilen (southeastern Tuva) are believed to indicate a shift from tectonic contraction, related to the mountain fold system formation, to postcollisional extension that ended with the disintegration of the collisional orogen. However, the position of composite dikes in the general sequence of magmatic events was based only on their geologic location and has not been confirmed by U/Pb isotope-geochronological data. The proposed study is concerned with the geologic structure, composition, and isotopic age (485–490 Ma) of West Sangilen composite dikes. The isotopic age of the host granites from the Matut pluton is 509 Ma; thermal events of Riphean (679–934 Ma) and early Paleozoic (484 Ma) age are reflected in zircons from gneiss-granites of the Erzin metamorphic complex. The obtained data are consistent with the earlier determined sequences of West Sangilen tectonometamorphic events. Basites from the examined composite dikes are strongly different in the contents of indicator elements (Rb, Nb, Ta, Zr, and Hf) and the Nb/Y, Zr/Y, Th/Ta, Zr/Nb, and Nb/Th ratios, which is indicative of different (probably, different-depth) mantle sources. The protolith of the salic component of the composite dikes might have been rocks similar in composition to the autochthonous/parautochthonous gneiss-granites of the Erzin metamorphic complex.

AB - Composite dikes (mingling dikes) of Western Sangilen (southeastern Tuva) are believed to indicate a shift from tectonic contraction, related to the mountain fold system formation, to postcollisional extension that ended with the disintegration of the collisional orogen. However, the position of composite dikes in the general sequence of magmatic events was based only on their geologic location and has not been confirmed by U/Pb isotope-geochronological data. The proposed study is concerned with the geologic structure, composition, and isotopic age (485–490 Ma) of West Sangilen composite dikes. The isotopic age of the host granites from the Matut pluton is 509 Ma; thermal events of Riphean (679–934 Ma) and early Paleozoic (484 Ma) age are reflected in zircons from gneiss-granites of the Erzin metamorphic complex. The obtained data are consistent with the earlier determined sequences of West Sangilen tectonometamorphic events. Basites from the examined composite dikes are strongly different in the contents of indicator elements (Rb, Nb, Ta, Zr, and Hf) and the Nb/Y, Zr/Y, Th/Ta, Zr/Nb, and Nb/Th ratios, which is indicative of different (probably, different-depth) mantle sources. The protolith of the salic component of the composite dikes might have been rocks similar in composition to the autochthonous/parautochthonous gneiss-granites of the Erzin metamorphic complex.

KW - Composite dikes

KW - Magma sources

KW - Mingling

KW - U–Pb isotopic age

KW - Western Sangilen

KW - Zircons

UR - http://www.scopus.com/inward/record.url?scp=85079488500&partnerID=8YFLogxK

U2 - 10.15372/RGG2019004

DO - 10.15372/RGG2019004

M3 - Article

VL - 60

SP - 45

EP - 66

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 1

ER -