Abstract

Xenotime is a significant accessory mineral which is being extensively used for precise U–Th–Pb geochronology by Electron Microprobe Analysis (EPMA). This paper presents a protocol for high analytical precision (<3% uncertainties on the measured ages) developed for the accurate estimation of U–Th and Pb content in xenotime using SXFive EPMA at the Department of Geology, Banaras Hindu University, by deploying five spectrometers attached with TAP, LIF, LPET, LTAP and PET crystals. The protocol is applied to the xenotime grains of tonalite-trondhjemite-granodiorite-gneiss (TTG) rocks from the geochronologically well-constrained terrain of the Bundelkhand Craton, central India. The obtained xenotime age 2929±23 Ma of TTGs is in agreement with the earlier published Neoarchaen 2697±3 Ma Pb–Pb zircon ages from the same area which validates the authenticity of the analytical method developed at the BHU-EPMA facility.

Highlights

• Analytical protocol for high precision U–Th–Pb chemical dating of xenotime by EPMA.

• High precision ages from TTG gneiss of the Bundelkhand Craton, Central India.

• Ages distinguishable from earlier reported ages from other techniques and samples.

• Validates the authenticity of the analytical method developed at the BHU-EPMA facility.

中文翻译：

---

使用CAMECA SXFive电子探针显微分析仪，对印度中部邦德汉德·克拉顿的TTG片麻岩中的Xenotime进行高精度U-Th-Pb化学测年的新分析协议

摘要

Xenotime是一种重要的辅助矿物，通过电子微探针分析（EPMA）被广泛用于精确的U–Th–Pb年代学。本文提出了一种高分析精度的协议（在测得的年龄中不确定性<3％），该协议通过部署五个光谱仪使用SXFive EPMA在巴那拉斯印度大学地质学系精确估计了异时中的U-Th和Pb含量。附带TAP，LIF，LPET，LTAP和PET晶体。该协议适用于印度中部邦德尔坎德·克拉顿（Bundelkhand Craton）地质年代学上受到严格限制的地形的斜方晶石-长晶硬岩-斜辉石-片麻岩（TTG）的异时粒。

强调

• EPMA对异戊二烯的U-Th-Pb高精度化学定年的分析规程。

• 来自印度中部Bundelkhand Craton的TTG片麻岩的高精度陈年。

• 可与其他技术和样本中较早报道的年龄区分开的年龄。

• 验证BHU-EPMA工厂开发的分析方法的真实性。