Multiple intrusion stages and mantle sources of the Paleozoic Kuznetsk Alatau alkaline province, Southern Siberia: geochemistry and Permian U–Pb, Sm–Nd ages in the Goryachegorsk ijolite-foyaite intrusion

ABSTRACT

In this work, we present new U–Pb, Sm–Nd geochronology, major and trace‐element and isotopic composition (Nd, Sr, Pb, O) for the Goryachegorsk alkaline-mafic igneous rocks from the Kuznetsk Alatau (Siberia, Russian Federation). The age obtained using U-Pb in zircon, ~ 265 Ma, is considered to represent the crystallization age of Goryachegorsk intrusion in Late Permian times. LILE and HFSE composition, and isotope signatures indicate the heterogeneity of magmatic sources and the mixing of IAB- and OIB- like magmas. We interpret that this intrusion is characterized by the superposition of PREMA + EM 2 mantle plume magmas and other magmas derived from the melting of accretion-collision complexes from the Paleo Asian ocean margin. Mixing of mantle sources and continental crust resulted in variations of Nd-isotope composition (ε_Nd (t) ~ 1.7–6.8) and lead isotope composition (²⁰⁶Pb/²⁰⁴Pb_in 19.29, ²⁰⁷Pb/²⁰⁴Pb_in 15.58, ²⁰⁸Pb/²⁰⁴Pb_in 37.74), as well as an increase of ⁸⁷Sr/⁸⁶Sr (t) ~ 0.7049–0.7068 and δ¹⁸О 8.5–9.6 ‰, SMOW in igneous rocks. Additional geochronological data on the Kuznetsk Alatau alkaline mafic province suggest its origin at different times during the Paleozoic: at the Cambrian-Ordovician boundary (~ 510–480 Ma); Early-Middle Devonian (~ 410–385 Ma); and Late Permian (~ 266–262 Ma). Geochemical similarity between the regional alkaline magmatism emplaced at different ages provides insights into periodic mantle plume – lithosphere interaction over a time span of ca. 250 Ma.

KEYWORDS:

• Alkaline magmatism
• geochemistry
• geochronology
• mantle plume
• kuznetsk Alatau
• central Asian orogenic belt

Acknowledgments

We would like to thank employees of the Analytical center “Geochemistry of natural systems” of Tomsk State University, IGM SB RAS, Department of mineralogy and geology of Dresden natural history museum, Geological institute of KSC RAS, Geological institute RAS, Pacific center of isotopic and geochemical research of British Columbia University for participation in the research. This work (Isotope analyses of rocks and minerals) was financially supported by mega-grant in accordance with Resolution of the RF Government (Agreement no. 14.Y26.31.0012). Interpretation of the Ordovician zircons data supported by grant of Russian Science Foundation (project No. 18-17-00240). GGA is also supported by Spanish Ministry of Science, innovation and universities under the project IBERCRUST (PGC2018-096534-B-I00). Dr. Javier Fernández-Suárez is thanked for his help and advice while elaborating this work. Insightful reviews by J.B. Murphy, an anonymous reviewer and the journal editor, R.J. Stern, greatly improved the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the Ministerio de Ciencia e Innovación [PGC2018-096534-B-I00]; Government of the Russian Federation [14.Y26.31.0012]; Russian Science Foundation [18-17-00240].