Trace element contents in white mica and tourmaline from the Panasqueira W-Sn-Cu deposit (Portugal)

Analyzing the chemical composition of rocks and minerals is an important tool for exploring and understanding mineral resources. Typically, hydrothermal ore deposits are characterized by primary alteration halos. At the world-class Panasqueira W-Sn-Cu deposit, the hydrothermal alteration of the wall rocks produced concentric zones with progressively greater distance from the veins, consisting of a proximal tourmaline-quartz-muscovite zone and a distal muscovite-quartz zone.

Panasqueira is a world-class W-Sn-Cu lode-type deposit located in the Castelo Branco district (Beira Baixa, central Portugal). The ore deposit consists of a swarm of sub-horizontal veins associated with a Late-Variscan S-type granite and enclosed by a metasedimentary unit of Late Ediacaran to Early Cambrian age (e.g., Kelly and Rye, 1979; Romão et al., 2013).

The veins are mainly composed of gangue quartz, muscovite and minor carbonates, apatite, topaz, topaz, fluorite, tourmaline, rutile, ilmenite, arsenopyrite, sphalerite, pyrite, marcasite, stannite, and pyrrhotite. Mineralization of wolframite, chalcopyrite, and cassiterite is predominantly hosted in veins with minor stringers and lenses of sulfide minerals in the wall rocks (e.g., Kelly and Rye, 1979; Polya, 1989; Polya et al., 2000). Although there is a strong variation in the vein mineralogy, typically, the quartz vein-filling is rimmed by a muscovite selvage up to 4-5 cm thick. The hydrothermal alteration produced a 2 to 30 cm thick tourmaline-rich alteration halo in the metasedimentary host rock (Bussink, 1984).

Tourmaline and mica are ubiquitous minerals at Panasqueira W-Sn-Cu and coexist in many other hydrothermal ore deposits worldwide. Both minerals are well-known to host variable amounts of trace elements and to have potential as pathfinder minerals as well as fluid monitors.

We analyzed major, minor and trace element contents of altered and unaltered metasediments from the Panasqueira by XRF and ICP-MS and tourmaline and white mica major, minor and trace element compositions by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in previously well-characterized samples from different locations/setting in the mine (greisen, vein-selvages, wall-rock alteration zones, fault zone, and late vugs).

The analyzed samples are described by Codeço et al. (2017), Codeço et al. (2019), and Codeço et al. 2020). These studies discuss the chemical (major, minor, and trace elements) and boron-isotopic compositions of tourmaline and white mica, and whole-rock chemistry of altered and unaltered metasediments. Further details on sample description can be found in the folder "2020-002_Codeco-et-al_Samples" and the analytical methods are described in " 2020-002_Codeco-et-al_data-description.pdf".

Detailed information about the samples used, the location, and general geological background of the samples, and the analytical method is provided in the data description "2020-002_Codeco-et-al_data-description.pdf ".

岩石与矿物的化学成分分析，是探索与认知矿产资源的重要技术手段。热液矿床（hydrothermal ore deposits）通常以原生蚀变晕为典型特征。在世界级潘纳斯奎拉（Panasqueira）钨-锡-铜矿床中，围岩经热液蚀变后形成了距矿脉距离递增的同心环带，分为近矿电气石（tourmaline）-石英-白云母（muscovite）带与远矿白云母-石英带。电气石（tourmaline）与云母（mica）是潘纳斯奎拉钨-锡-铜矿床中广泛产出的矿物，同时也在全球诸多其他热液矿床中伴生产出。这两种矿物均已知可赋存含量不一的微量元素，兼具作为找矿指示矿物与流体示踪矿物的潜力。本次研究采用X射线荧光光谱法（XRF）与电感耦合等离子体质谱法（ICP-MS），分析了潘纳斯奎拉矿床中蚀变与未蚀变变沉积岩的主量、次要与痕量元素含量；同时利用激光剥蚀电感耦合等离子体质谱法（LA-ICP-MS），测定了该矿不同采区/地质背景下（云英岩（greisen）、脉旁带（vein-selvages）、围岩蚀变带、断裂带（fault zone）及晚期晶洞（vugs））已完成详细表征的样品中电气石与白云母的主量、次要与痕量元素组成。本次研究所用样品的详细信息、采样点位、样品所属区域的基础地质背景，以及分析方法细节，均已在数据说明文件《2020-002_Codeco-et-al_data-description.pdf》中予以说明。