ABSTRACT

The metallogenic belt containing numerous skarn mineralized systems starting from Eastern Europe continues through Turkey and Iran. The study area in the Eastern Pontides is within this metallogenic belt. The 44.39 ± 0.53 Ma Karadağ Intrusion sourced skarn mineralization is located along the granitoid-to-limestone contact. The Karadağ Intrusion is an arc-like pluton with medium–high K calc-alkaline and peraluminous–metaluminous affinity. The Karadağ Fe–Cu skarn mineralization (Gümüşhane, Turkey), an exoskarn, is hosted by Late Cretaceous limestone and consists of early garnet, clinopyroxene, and orthoclase with late epidote and chlorite. Primary ore minerals are magnetite and haematite, accompanied by minor amounts of chalcopyrite and pyrite. Pyroxene comprises mostly diopside and less hedenbergitic diopside and johannsenite. Wollastonite is very rare. Garnet is andradite and grossular–andradite. Thus, all these results imply that the Karadağ Fe–Cu skarn mineralization formed under relatively oxidized and Fe-rich conditions. The homogenization temperatures of the fluid inclusions vary from 189°C to 405°C for quartz and 186°C to 430°C for calcite. The salinity contents in the fluid inclusions are within 0.2–9 wt% NaCl equivalent for quartz and 0.4–14.8 wt% NaCl equivalent for calcite. First melting temperatures between −36.5 and −47.4°C were attained with the presence of NaCl–FeCl₂± CaCl₂ in the initial phase of fluid inclusions. The first melting in the later stage of fluid inclusions is between −3.8 and −17.2°C, thereby, supporting the existence of NaHCO₃-Na₂CO₃-KCl-type salt composition. The δ¹⁸O values of minerals are 1.7–10.3‰ for garnet, 11.1–14.6‰ for quartz, 6.4 to 6.8‰ for epidote, and 2.8–3.8‰ for magnetite in the Karadağ skarn mineralization. The δ¹⁸O value of epidote indicates magmatic fluid, whereas those of garnet, magnetite, and quartz suggest magmatic fluids together with less meteoric effect. The δ¹⁸O values in limestone (18.7 to 22.3‰), marble (8.7‰), and calcite (10.5 to 12.2‰) were depleted relative to typical δ¹⁸O contents of marine carbonates (20 to 30‰). Moreover, the C isotope values of calcite (−5.4 to −1.4‰), marble (−2.1‰), and limestone (1.0 to 1.2‰) reflect those of metamorphic rocks and skarns (−4.0 to 3‰ and −18 to 2‰). Mineral paragenesis, fluid inclusion, and stable isotopic signatures are consistent with ore mineralization caused by the interaction of magmatic fluids with carbonate host rocks. Karadağ Fe-Cu skarn mineralization, associated with Karadağ postcollisional magmatism, is an example of skarn mineralized system in the Eastern Pontides.

摘要

从东欧开始，含有大量矽卡岩矿化系统的成矿带继续穿过土耳其和伊朗。东庞蒂斯研究区位于该成矿带内。44.39 ± 0.53 Ma Karadağ Intrusion 来源的矽卡岩矿化位于花岗岩-石灰岩接触沿线。Karadağ 侵入体是一种弧形岩体，具有中高钾钙碱性和过铝-金属亲和力。Karadağ Fe-Cu 矽卡岩矿化（土耳其 Gümüşhane）是一种外积岩，以晚白垩世石灰岩为主，由早期石榴石、单斜辉石和具有晚期绿帘石和绿泥石的正长石组成。原生矿石矿物为磁铁矿和赤铁矿，并伴有少量黄铜矿和黄铁矿。辉石主要由透辉石和较少的hedenbergitic透辉石和johannsenite组成。硅灰石非常稀有。石榴石是钙铁榴石和钙铝榴石。因此，所有这些结果表明，卡拉达格铁铜矽卡岩矿化是在相对氧化和富铁条件下形成的。流体包裹体的均质化温度从石英的 189°C 到 405°C 不等，方解石的 186°C 到 430°C 不等。流体包裹体中的盐度含量在石英的 0.2-9 wt% NaCl 当量和方解石的 0.4-14.8 wt% NaCl 当量范围内。在存在 NaCl-FeCl 的情况下，首次熔化温度在 -36.5 和 -47.4°C 之间 流体包裹体的均质化温度从石英的 189°C 到 405°C 不等，方解石的 186°C 到 430°C 不等。流体包裹体中的盐度含量在石英的 0.2-9 wt% NaCl 当量和方解石的 0.4-14.8 wt% NaCl 当量范围内。在存在 NaCl-FeCl 的情况下，首次熔化温度在 -36.5 和 -47.4°C 之间 流体包裹体的均质化温度从石英的 189°C 到 405°C 不等，方解石的 186°C 到 430°C 不等。流体包裹体中的盐度含量在石英的 0.2-9 wt% NaCl 当量和方解石的 0.4-14.8 wt% NaCl 当量范围内。在存在 NaCl-FeCl 的情况下，首次熔化温度在 -36.5 和 -47.4°C 之间₂ ± CaCl ₂在流体夹杂物的初始阶段。流体包裹体后期的第一次熔化在-3.8和-17.2°C之间，从而支持NaHCO ₃ -Na ₂ CO ₃ -KCl型盐成分的存在。Karadağ矽卡岩矿化矿物δ ^{18 O值分别为石榴石1.7~10.3‰、石英11.1~14.6‰、绿帘石6.4~6.8‰、磁铁矿2.8~3.8‰。}绿帘石的δ ¹⁸ O 值表示岩浆流体，而石榴石、磁铁矿和石英的δ 18 O 值表示岩浆流体以及较少的流星效应。δ ¹⁸石灰石（18.7 至 22.3‰）、大理石（8.7‰）和方解石（10.5 至 12.2‰）中的 O 值相对于海相碳酸盐的典型 δ ¹⁸ O 含量（20 至 30‰）有所减少。此外，方解石（-5.4 至 -1.4‰）、大理石（-2.1‰）和石灰石（1.0 至 1.2‰）的 C 同位素值反映了变质岩和矽卡岩的碳同位素值（-4.0 至 3‰ 和 -18 至 2 ‰)。矿物共生、流体包裹体和稳定同位素特征与岩浆流体与碳酸盐母岩相互作用引起的矿石成矿一致。Karadağ Fe-Cu 矽卡岩矿化与 Karadağ 碰撞后岩浆作用有关，是东庞蒂斯地区矽卡岩矿化系统的一个例子。