Extreme H isotope fractionation of phyllosilicates from the Kiggavik Uranium deposits

IF 4.6 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Journal of Geochemical Exploration Pub Date : 2026-03-01 Epub Date: 2025-12-03 DOI:10.1016/j.gexplo.2025.107945

Ian Burron , Mostafa Fayek , Julie Brown , Alfredo Camacho

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引用次数: 0

Abstract

The Kiggavik Uranium (U) Project in Nunavut, Canada hosts U deposits for which both unconformity-related and metasomatic‑iron-alkali-calcic genetic models have been proposed. We propose a five-phase genetic model consisting of: (1) albitization; (2) hematization and illitization; (3) bleaching and primary (U1) mineralization; (4) ∼1450 Ma to 274 Ma overprinting events linked to distant tectonic and igneous events, and: (5) geologically recent (∼471 Ka to 36 Ka) overprinting linked to subglacial meteoric fluids.

M2 muscovite formed during albitization of granitic rocks and is Ar-Ar dated to ∼1820–1830 Ma, which is consistent with igneous and seismic activity and albitite-hosted U mineralization in the region. M2 muscovite has δ²H values as high as +129 ‰. This high value is unprecedented in terrestrial minerals. M2 is in equilibrium with isotopically heavy (δ¹⁸O and δ²H values of +10.4 ± 2.1 ‰ and + 130 ± 31 ‰, respectively) fluids proposed to have been produced through multiple cycles of seismically-induced fluid boiling, phase separation, and condensation.

Multiple generations of illite, formed through retrograde metamorphic (Il1) and subsequent hydrothermal (Il2-Il5) processes, are present. Il3 and Il5 are isotopically consistent with precipitation from basinal fluids and with subsequent overprinting by meteoric fluids, while Il4 is isotopically consistent with highly fractionated, boiled fluids. Il3-Il5 illites yield post U1 Ar-Ar dates, reflecting overprinting events.

Highly fractionated fluids are strongly linked to albitization and an early albitite-style U mineralization event. Both highly fractionated and basinal fluids may have been involved in U1 mineralization. Basinal and meteoric fluids are strongly linked to post-depositional alteration events.

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基加维克铀矿床层状硅酸盐的极端H同位素分馏

加拿大Nunavut的Kiggavik铀(U)项目拥有铀矿床，其不整合成因模式和交代-铁-碱-钙成因模式已被提出。我们提出了一个五阶段的遗传模型，包括：(1)脂肪化；(2)溶血和消毒；(3)漂白和原生矿化（U1）；(4)与遥远的构造和火成岩事件有关的~ 1450 Ma ~ 274 Ma套印事件，以及(5)与冰下大气流体有关的地质近代（~ 471 Ka ~ 36 Ka）套印事件。M2白云母形成于花岗岩体钠长石化时期，Ar-Ar年代为~ 1820-1830 Ma，与该区火成岩和地震活动以及钠长石含铀成矿作用一致。M2白云母的δ2H值高达+129‰。如此高的价值在陆生矿物中是前所未有的。M2与同位素重流体（δ18O和δ2H值分别为+10.4±2.1‰和+ 130±31‰）处于平衡状态，这些流体可能是通过地震诱发的流体沸腾、相分离和冷凝的多次循环产生的。通过逆行变质（Il1）和随后的热液（Il2-Il5）过程形成的多代伊利石。Il3和Il5的同位素特征与盆地流体沉淀和随后的大气流体套印相一致，而Il4的同位素特征与高度分馏的沸腾流体相一致。Il3-Il5 illites在U1 Ar-Ar日期后产生，反映套印事件。高分馏流体与钠长石化和早期钠长石型铀成矿事件密切相关。高分馏流体和盆地流体可能都参与了U1矿化。盆地流体和大气流体与沉积后蚀变事件密切相关。

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来源期刊

Journal of Geochemical Exploration 地学-地球化学与地球物理

CiteScore

7.40

自引率

7.70%

发文量

148

审稿时长

8.1 months

期刊介绍： Journal of Geochemical Exploration is mostly dedicated to publication of original studies in exploration and environmental geochemistry and related topics. Contributions considered of prevalent interest for the journal include researches based on the application of innovative methods to: define the genesis and the evolution of mineral deposits including transfer of elements in large-scale mineralized areas. analyze complex systems at the boundaries between bio-geochemistry, metal transport and mineral accumulation. evaluate effects of historical mining activities on the surface environment. trace pollutant sources and define their fate and transport models in the near-surface and surface environments involving solid, fluid and aerial matrices. assess and quantify natural and technogenic radioactivity in the environment. determine geochemical anomalies and set baseline reference values using compositional data analysis, multivariate statistics and geo-spatial analysis. assess the impacts of anthropogenic contamination on ecosystems and human health at local and regional scale to prioritize and classify risks through deterministic and stochastic approaches. Papers dedicated to the presentation of newly developed methods in analytical geochemistry to be applied in the field or in laboratory are also within the topics of interest for the journal.