Fluorite (U-Th)/He geochronology: methodical development and case studies

萤石 (U-Th)/He 地质年代学：方法开发和案例研究

• 批准号: 183931056
• 负责人: Dr. István Dunkl
• 金额: --
• 依托单位: Abteilung Sedimentologie und Umweltgeologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/183931056?language=en
• 关键词: Fluorite; Th; He; geochronology; methodical

Fluorite is a widespread mineral species that forms in highly variable geological environments ranging from pegmatitic to diagenetic conditions. The few data available suggest that this mineral is suitable for (U-Th)/He geochronology although its closure temperature is not known yet. We plan to study the diffusion of helium in fluorite and its possible dependence on crystallographic parameters on various natural fluorites in order to determine experimentally the closure temperature of the fluorite-He thermochronometer. Additionally two types of natural case studies will be investigated: (i) fluorite occurrences where the fluorite-He ages could be related to the thermal history of the region as constrained by several independent thermochronometers. This allows for deriving an empirical closure temperature. (ii) Fluorite-He, Sm/Nd and geochemical data of carbonate-hosted fluorite (mostly diagenetic or fluorite-bearing Pb-Zn ore deposits) will be used to constrain the genetic conditions and derive thermochronological data of such occurrences. The development of the method has strong potential with respect to thermochronology of apatite and zircon-free lithologies such as carbonate nappes of fold-and-thrust belts.

萤石是一种分布广泛的矿物物种，形成于从伟晶岩到成岩条件的高度可变的地质环境中。为数不多的资料表明，这种矿物适合于(U-Th)/He年代学，尽管其闭合温度尚不清楚。我们计划研究氦在萤石中的扩散及其对各种天然萤石的可能的晶体参数的依赖关系，以便从实验上确定萤石-氦热时计的封闭温度。此外，还将调查两种类型的自然案例研究：(I)萤石产状，其中萤石-He年龄可能与该地区的热历史有关，受几个独立的温度计时器制约。这允许推导出经验闭合温度。(Ii)将利用萤石-He、Sm/ND和碳酸盐萤石(主要是成岩或含萤石铅锌矿床)的地球化学数据来约束这些产出的成因条件，并得出这些产出的热年代学数据。该方法在磷灰石的热年代学和无锆石岩性方面具有很强的潜力，如褶皱冲断带的碳酸盐推覆体。

项目成果

Variable helium diffusion characteristics in fluorite

萤石中不同的氦扩散特性

• DOI: 10.1016/j.gca.2016.05.029
• 发表时间: 2016
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Stockli;Wiedenbeck;von Eynatten
• 通讯作者: von Eynatten

The Age of the Latest Thermal Overprint of Tin and Polymetallic Deposits in the Erzgebirge, Germany: Constraints from Fluorite (U-Th-Sm)/He Thermochronology

• DOI: 10.2113/econgeo.110.8.2025
• 发表时间: 2015-12
• 期刊: Economic Geology
• 影响因子: 5.8
• 作者: R. Wolff;I. Dunkl;U. Kempe;H. Eynatten

Superposition of burial and hydrothermal events: post‐Variscan thermal evolution of the Erzgebirge, Germany

埋藏和热液事件的叠加：德国厄尔士山脉的后瓦里斯坎热演化

• DOI: 10.1111/ter.12159
• 发表时间: 2015
• 期刊: Terra Nova
• 影响因子: 2.4
• 作者: T. von Eynatten