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.

摘要

在这项工作中，我们提出了来自库兹涅茨克阿拉套（西伯利亚，俄罗斯联邦）的戈里亚切戈尔斯克碱性基性火成岩的新 U-Pb、Sm-Nd 年代学、主要和微量元素以及同位素组成（Nd、Sr、Pb、O） ）。使用锆石中的 U-Pb 获得的年龄约为 265 Ma，被认为代表了晚二叠世 Goryachegorsk 侵入体的结晶年龄。LILE 和 HFSE 组成以及同位素特征表明岩浆来源的非均质性以及 IAB 和 OIB 类岩浆的混合。我们认为这次侵入的特征是 PREMA + EM 2 地幔柱岩浆与来自古亚洲洋边缘的吸积碰撞复合体熔化的其他岩浆的叠加。地幔源和大陆地壳的混合导致 Nd 同位素组成（ε_钕（T）〜1.7-6.8）和铅同位素组成（²⁰⁶ PB / ²⁰⁴铅_在19.29，²⁰⁷的Pb / ²⁰⁴铅_在15.58，²⁰⁸的Pb / ²⁰⁴铅_在37.74），以及增加了⁸⁷ SR / ⁸⁶锶(t) ~ 0.7049–0.7068 和 δ ¹⁸О 8.5–9.6 ‰, 火成岩中的 SMOW。库兹涅茨克阿拉套碱性镁铁质省的其他地质年代学数据表明其起源于古生代不同时期：寒武纪-奥陶纪边界（~510-480 Ma）；早中泥盆世 (~ 410–385 Ma)；和晚二叠世（~ 266-262 Ma）。不同时代发生的区域碱性岩浆作用之间的地球化学相似性提供了对约 10 年时间跨度内周期性地幔柱-岩石圈相互作用的见解。250 毫安。