Geology, fluid inclusions and C−O−S−Pb isotopic compositions of the Chahmileh Pb-Zn deposit, Central Iran: Implications for ore genesis

IF 2 3区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Geological Magazine Pub Date : 2024-04-04 DOI:10.1017/s0016756823000766

Behzad Mehrabi, Nafiseh Chaghaneh, Ebrahim Tale Fazel, Fernando Corfu

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Abstract

The Chahmileh Pb–Zn deposit, located northwest of the Central Iran Zone, is a sediment-hosted Pb–Zn deposit in the ‘Yazd-Anarak Metallogenic Belt’. It is hosted in Middle Triassic carbonate rocks and is mainly controlled by NW-trending faults. The main ore minerals are galena and sphalerite with minor chalcopyrite, pyrite, and quartz, dolomite, along with minor calcite and baryte as gangue minerals. Cerussite, hemimorphite, wulfenite, mimetite, smithsonite, malachite and iron oxy-hydroxides are the main non-sulphide ore minerals. The main styles of mineralization are vein-veinlet, breccia, disseminated and replacement in association with silicification and dolomitization. Microthermometry of fluid inclusions in dolomite and quartz indicates that the ore precipitated from a warm to hot basin-derived saline fluid. Dolomite samples have δ13CVPDB and δ18OVSMOW values of −0.99 to +1.99‰ and +20.74 to +25.48‰, respectively, and are plotted in the marine carbonate rocks field. These isotopic values suggest that CO2 in the hydrothermal fluids mainly originated from marine carbonate rock. The δ34S values range from +6.3 to +8.2‰ for galena, +5.9 to +6.2‰ for sphalerite, +1.4 to +3.4‰ for chalcopyrite and +15.0 to +17.4‰ for bayite are compatible with a predominant thermochemical sulphate reduction process, and with sulphur sourced from Triassic seawater. Galena samples have a homogeneous Pb isotopic composition that is indicative of a continental crustal reservoir as the main source of lead and probably for the other ore metals. Based on geology, mineralogy, texture and fluid characteristics, the Chahmileh deposit is classified as a carbonate-hosted Mississippi Valley-type deposit.

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伊朗中部 Chahmileh 铅锌矿床的地质、流体包裹体和 C-O-S-Pb 同位素组成：对矿石成因的影响

Chahmileh 铅锌矿床位于伊朗中部地区西北部，是 "亚兹德-安纳拉克金属成矿带 "中的沉积矿床。它赋存于中三叠统碳酸盐岩中，主要受西北走向断层控制。主要矿石矿物为方铅矿和闪锌矿，以及少量黄铜矿、黄铁矿、石英和白云石，还有少量方解石和重晶石作为煤矸石矿物。主要的非硫化物矿石矿物是铈镧矿、半闪长岩、乌辉石、闪长岩、铁闪长岩、孔雀石和铁氧氢氧化物。矿化的主要类型有脉状、角砾岩状、浸染状和置换状，并伴有硅化和白云石化。对白云石和石英中的流体包裹体进行的微测温表明，矿石是从温暖到炎热的盆地盐水流体中析出的。白云岩样本的δ13CVPDB和δ18OVSMOW值分别为-0.99至+1.99‰和+20.74至+25.48‰，并绘制在海洋碳酸盐岩区域。这些同位素值表明热液中的二氧化碳主要来源于海相碳酸盐岩。方铅矿的δ34S值在+6.3至+8.2‰之间，闪锌矿的δ34S值在+5.9至+6.2‰之间，黄铜矿的δ34S值在+1.4至+3.4‰之间，贝叶石的δ34S值在+15.0至+17.4‰之间。方铅矿样品具有均匀的铅同位素组成，表明大陆地壳储层是铅的主要来源，也可能是其他矿石金属的主要来源。根据地质学、矿物学、质地和流体特征，Chahmileh 矿床被归类为碳酸盐岩包裹的密西西比河谷型矿床。

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来源期刊

Geological Magazine 地学-地球科学综合

CiteScore

4.70

自引率

0.00%

发文量

111

审稿时长

3 months

期刊介绍： Geological Magazine, established in 1864, is one of the oldest and best-known periodicals in earth sciences. It publishes original scientific papers covering the complete spectrum of geological topics, with high quality illustrations. Its worldwide circulation and high production values, combined with Rapid Communications and Book Review sections keep the journal at the forefront of the field. This journal is included in the Cambridge Journals open access initiative, Cambridge Open Option.