To determine the origin of the Kohlou barite deposit, comprehensive studies on petrography, rare earth element (REE) geochemistry, oxygen and sulfur isotopes, and fluid inclusions were performed. The Kohlou deposit is located 70 km northwest of Tafresh town in Markazi Province, Iran. Barite mineralization occurs as a stratabound manto at the contact of an overlying Eocene-aged volcano-sedimentary sequence with an underlying limestone horizon. Barite is accompanied by subordinate Fe- and Mn-oxides, calcite, and quartz. Field evidence including the presence of barite veinlets cross cutting host tuffs, and the brecciated host rocks cemented by barite suggest an epigenetic origin for the mineralization. The concentration of ∑REE is very low in barites, ranging from 0.22 to 16.41 ppm. Chondrite-normalized REE patterns show LREE enrichment relative to HREE, and mostly negative La and Ce anomalies. Gadolinium (Gd) anomalies vary from negative to positive in barite samples. The Ce/La and Y/Ho ratios, as well as La and Gd anomalies confirm a terrestrial source for barite from the Kohlou deposit. The δ¹⁸O and δ³⁴S isotopic ratios in barites fall in narrow ranges of 1.7–2.7‰ and 14.6–16.3‰, respectively, implying that sulfate originated most likely from adjacent Miocene evaporites, with minor components of magmatic sulfur and oxygen carried in mineralizing fluids. Plots of δ³⁴S versus δ¹⁸O do not show any similarity to barites from main modern marine and pedogenic settings, while overlap with the field represented by continental barite. Salinity values in fluid inclusions range from 8.28 to 23.25 wt% NaCl + CaCl₂ equivalent. Homogenization temperatures occupy the range of 139–272 °C. Fluid inclusion data indicate that basinal fluids, with minor contribution from meteoric water, were the source of mineralizing solutions. It is concluded here that faulting and brecciation of the host rocks provided the pathways needed for the upward migration of the basinal Ba-rich solutions. Barite precipitated where Ba-bearing fluids interacted evaporite deposits.

为确定 Kohlou 重晶石矿床的成因，对岩相学、稀土元素 (REE) 地球化学、氧和硫同位素以及流体包裹体进行了综合研究。Kohlou矿床位于伊朗马尔卡齐省Tafresh镇西北70公里处。重晶石矿化发生在上覆始新世火山沉积层序与下伏石灰岩层的接触处的层状曼托。重晶石伴随着次要的铁和锰氧化物、方解石和石英。现场证据包括重晶石细脉横切主凝灰岩的存在，以及由重晶石胶结的角砾化主岩表明矿化的表观成因。重晶石中 ∑REE 的浓度非常低，范围为 0.22 至 16.41 ppm。球粒陨石归一化 REE 模式显示 LREE 相对于 HREE 富集，并且大多为负 La 和 Ce 异常。重晶石样品中的钆 (Gd) 异常从负到正不等。Ce/La 和 Y/Ho 比，以及 La 和 Gd 异常证实了 Kohlou 矿床重晶石的陆地来源。δ^{重晶石中的18} O 和 δ ³⁴ S 同位素比值分别在 1.7-2.7‰ 和 14.6-16.3‰ 的狭窄范围内，这表明硫酸盐最可能起源于相邻的中新世蒸发岩，矿化液中携带了少量岩浆硫和氧成分. δ ³⁴ S 与 δ ¹⁸ O 的图与现代主要海洋和成土环境中的重晶石没有任何相似之处，而与以大陆重晶石为代表的领域重叠。流体包裹体中的盐度值范围为 8.28 至 23.25 wt% NaCl + CaCl ₂相等的。均化温度范围为 139–272 °C。流体包裹体数据表明，来自大气水的少量贡献的盆地流体是矿化溶液的来源。得出的结论是，主岩的断层和角砾化为盆地富钡溶液向上迁移提供了所需的通道。重晶石在含钡流体与蒸发岩沉积物相互作用的地方沉淀。