Abstract Rare earth element (REE) and Y contents along with Sr-Nd isotopic ratios have been determined in fluorite and calcite samples from the two main veins of the Silius deposit, hosted in Lower Paleozoic metavolcanic rocks, in southern Sardinia. Fluorite from the late San Giuseppe vein contains higher (107–336 mg/kg) (REE + Y) than fluorite from the early San Giorgio vein (29–94 mg/kg), whereas calcite exhibits a range (175–440 mg/kg) overlapping with that of San Giuseppe fluorite. Irrespective of either vein, the 87Sr/86Sr ratios of fluorite range from 0.71106 to 0.71566, overlapping with those of calcite (0.71257–0.71406), whereas the 143Nd/144Nd ratios are slightly higher for fluorite (0.51221–0.51236) than calcite (0.51211–0.5122). Moreover, the 147Sm/144Nd versus 143Nd/144Nd ratio relationship suggests that San Giuseppe fluorites were deposited by 294 ± 40 Ma, whereas it yields no information for San Giorgio fluorites. Assuming 270 Ma as the most probable age of emplacement, the initial Sr-Nd isotopic ratios and (REE + Y) contents in fluorite indicate the crustal origin of Silius mineralizing fluids, likely from mixing in different proportions of evaporated seawater brines with fluids from the Paleozoic siliciclastic basement and Late Variscan/post-Variscan magmatic rocks. Mineralizing fluids evolved their chemical and isotopic composition through interaction with wallrocks and/or dilution with meteoric waters circulating through the Paleozoic basement. As a whole, the chemical and isotopic composition of fluorite from the Silius deposit resembles that of other fluorite deposits from Variscan Europe.

中文翻译：

---

Silius 脉矿床（意大利撒丁岛东南部）萤石起源的稀土元素和 Sr-Nd 同位素证据

摘要 在来自撒丁岛南部下古生代变质火山岩中的 Silius 矿床的两个主要矿脉的萤石和方解石样品中测定了稀土元素 (REE) 和 Y 含量以及 Sr-Nd 同位素比。来自晚期圣朱塞佩脉的萤石比来自早期圣朱塞佩脉的萤石 (29-94 毫克/千克) 含有更高 (107-336 毫克/千克) (REE + Y)，而方解石表现出范围 (175-440 毫克/千克) kg) 与 San Giuseppe 萤石重叠。不管是哪一种脉，萤石的 87Sr/86Sr 比率范围从 0.71106 到 0.71566，与方解石的比率 (0.71257–0.71406) 重叠，而 143Nd/144Nd 比率对于 2222105-2221210.10.10.143Nd 的比率略高于 22213-10.10.10.22210.10.10.10.10.2222101-10.10.10.10.10.5222161-10.521210.144Nd 比率略高于方解石。 0.5122）。而且，147Sm/144Nd 与 143Nd/144Nd 的比率关系表明圣朱塞佩萤石沉积于 294 ± 40 Ma，而它没有产生圣乔治萤石的信息。假设最可能的侵位年龄为 270 Ma，萤石中的初始 Sr-Nd 同位素比和 (REE + Y) 含量表明 Silius 矿化流体的地壳来源，可能来自不同比例的蒸发海水卤水与来自古生代硅质碎屑基底和晚瓦利斯坎/后瓦利斯坎岩浆岩。矿化流体通过与围岩相互作用和/或被流经古生代基底的大气水稀释而演化出它们的化学和同位素组成。总的来说，