Givetian-Frasnian rift-related volcanism of the Shipunikha Depression, NW Rudny Altai, Central Asia: Tectono-magmatic significance and new constraints on whole-rock geochemistry, Nd-isotopic data and U[sbnd]Pb ages
Kuibida M.L. Kruk N.N. Vikentiev I.V. Murzin O.V. Murzina N.M. Yakovlev V.A. Shelepov Y.Y. Chugaev A.V. Mizernaya M.A. Shelepaev R.A. Kotler P.D. Mikheev E.I. Nikolaeva I.V. Palesskiy S.V. Semenova D.V. Soloshenko N.G. Pyatkova A.P. Karmanov G.F.
15 December 2024Elsevier B.V.
Lithos
2024#490-491
The paper presents new original data on the Devonian rift-related volcanism from the Rudny Altai, a marginal terrane of the Siberian continent (Altai-Sayan Fold Belt, western Central Asian Orogenic Belt). The extensional regime in relation to tectono-magmatic reactivation of the continental margin was accompanied by an intense flare up of bimodal-type shallow-marine volcanism and injection of subvolcanic intrusions. On the first stage basic magmatism evolved from (i) injection of “More LREE- and HFSE-enriched” dolerite (εNd(t) = +5.1) to (ii) eruption of their effusive analogues (εNd(t) = +1.4), and following “Less LREE- and HFSE-enriched” basalt (εNd(t) = +6.1). This stage reflects initial opening of the rift. On the second stage, volcanism evolved from (iii) “LREE- and HFSE-depleted” (εNd(t) = +5.4) to (iv) “LREE-enriched and HFSE-depleted” (εNd(t) = +4.1 to +4.7) types. This stage correspond to the prolonged opening of the pull-apart basin, as there is no geological evidence for island-arc uplift during this period. Variations in indicator HFSE ratios (Th/Yb, Nb/Yb and Zr/Y), enrichment of Nb relative to La and Th in combination with moderate Nd isotopic values resemble those for basalts from the behind-arc region with close spatial-temporal relation to rifting. The trace element variation indicates a change in the partial melting degree of the mantle source, from lower to higher, consistent with progressive rifting. The petrogenesis of magmas has been interpreted as shallow melting of a lithospheric mantle, metosomatised by a previous subduction event, and inherited geochemical signatures of relict mantle. The voluminous felsic magmatism was formed by crustal melting during lithospheric extension when basic magmas reached high crustal levels. The dacites yield zircon U[sbnd]Pb ages of ca. 375 Ma, reflecting the peak of volcanic activity. The tectonic record bear evidence of strike-slip deformation, which could been induced by translation of arc and back-arc lithospheric plates. The Devonian evolution of the Altai Convergent Margin (NW Rudny Altai) of the Siberian continent was accompanied by the generation of basalt-dacite volcanism (∼380-375 Ma). Based on the sequence of volcanic phases and their geochemical variations in the time range, two stages corresponding to the initial and long-term opening of the pull-apart basin are distinguished. The petrogenesis of the magmas is interpreted as shallow melting of lithospheric mantle metasomatised by a previous subduction event and inheriting geochemical signatures of the relict mantle. The initial and subsequent magmatic phases can be reproduced by varying the degree of partial melting of the magma source from lower to higher, consistent with the evolution of the pull-apart basin. Rift-related magmatism is caused by arc and back-arc plate translation, with a minor role for subduction factor.
Back-arc basin , Bimodal basalt-dacite (rhyolite) formation , Continental lithosphere mantle , Rifted-arc , T- and E-MORB magmatism
Text of the article Перейти на текст статьи
Sobolev Institute of Geology and Mineralogy SB RAS, Koptyuga ave. 3, Novosibirsk, Russian Federation
Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Staromonetny Per., 35, Moscow, Russian Federation
Siberian research Institute of Geology, Geophysics and Mineral resources, Krasny prospect, 67, Novosibirsk, Russian Federation
Serikbaev East Kazakhstan Technical University, Serikbayeva St., 19, Ust-Kamenogorsk, Kazakhstan
Zavaritsky Institute of Geology and Geochemistry UB RAS, Akademika Vonsovskogo Str., 15, Ekaterinburg, Russian Federation
Sobolev Institute of Geology and Mineralogy SB RAS
Institute of Geology of Ore Deposits
Siberian research Institute of Geology
Serikbaev East Kazakhstan Technical University
Zavaritsky Institute of Geology and Geochemistry UB RAS
10 лет помогаем публиковать статьи Международный издатель
Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026