Abstract

Copper-rich deposits associated with magmatism at the Oued Belif -Ain El Araar area in North-western Tunisia fit into the geodynamic framework of the Tell-Rif orogenic belt of North Africa that extends westward to the Betic Cordilleras in Spain at the african and european plate boundary. The deposits have been considerably studied. However, the prevailing conditions of pressure, volume, temperature and composition (P-V-T-X) of the mineralizing fluids are still elusive. In this study, three types of fluid inclusions were distinguished for the mineralized facies: primary polyphase brine inclusions (Type I: liquid + vapor + halite + sylvite), primary sylvite (Type II-a: liquid + vapor + sylvite) and halite (Type II-b: liquid + vapor + halite) bearing inclusions and biphasic secondary vapor-rich and liquid-rich inclusions (Type III: liquid + vapor). Raman spectroscopy show that Type I and II a-b inclusions are in the CO₂–H₂O–NaCl–KCl, CO₂–H₂O–NaCl and CO₂–H₂O–KCl systems, whereas Type III pertains to the CO₂–H₂O system. Estimations of Pressure-Temperature fluid trapping conditions, for all mentioned inclusions, demonstrate a physicochemical fluid evolution from the highest temperature brine inclusions (T_t = 500°C; P_t = 980 bars), related to the porphyry phase, to the low temperature biphasic inclusions (T_t = 131°C; P_t = 221 bars) related the latest epithermal phase .The coexistence of liquid-rich and vapor-rich inclusions homogenizing at lower temperatures, confirms the establishment of boiling conditions responsible of Au–(Ag) enrichment in the last mineralizing phases. Comparable temperature conditions in similar magmatic related deposits are also mentioned in southern Spain (Rodalquilar gold mine, e.g., Arribas et al., 1995) where the mineralizing fluid temperatures mentioned vary from 175°C for epithermal deposits to more than 400°C for porphyry ones. The geochemical behavior of trace element indicates positive anomalies in mobile elements (hygromagmaphiles), those linked to Au, granitophiles (mainly W and Mo) and chalcophiles indicating a supply of metals of deep origin and mineralizing fluids with marked magmatic differentiation.

中文翻译：

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与 Oued Belif-Ain El Araar 岩浆构造斑岩、交代和浅成热液矿床相关的热液的地球化学和 PT 条件（北非高山造山运动，突尼斯）

摘要

突尼斯西北部 Oued Belif -Ain El Araar 地区与岩浆作用有关的富铜矿床符合北非 Tell-Rif 造山带的地球动力学框架，该造山带向西延伸至非洲和欧洲的西班牙贝蒂克科迪勒拉山脉板块边界。对这些矿床进行了大量研究。然而，矿化流体的压力、体积、温度和成分（PVTX）的主要条件仍然难以捉摸。本次研究中，矿化相区分出三种类型的流体包裹体：原生多相卤水包裹体（I型：液体+蒸汽+石盐+钾盐）、原生钾盐（II-a型：液体+蒸汽+钾盐）和石盐（ II-b型：液体+蒸汽+石盐）含有包裹体和双相次生富蒸汽和富液体包裹体（III型：液体+蒸汽）。拉曼光谱显示，I型和II型ab夹杂物属于CO ₂ –H ₂ O–NaCl–KCl、CO ₂ –H ₂ O–NaCl和CO ₂ –H ₂ O–KCl体系，而III型属于CO ₂ -H ₂ O体系。对所有提到的包裹体的压力-温度流体捕获条件的估计表明，从与斑岩相相关的最高温度盐水包裹体（T _t = 500°C；P _t = 980 巴）到低温的物理化学流体演化双相包裹体（T _t = 131°C；P _t = 221 条）与最新的浅热相有关。富含液体和富含蒸汽的包裹体在较低温度下均质化的共存，证实了沸腾条件的建立，导致 Au–(Ag ）最后矿化阶段的富集。西班牙南部也提到了类似岩浆相关矿床的可比温度条件（Rodalquilar 金矿，例如 Arribas 等，1995），其中提到的矿化流体温度从浅成热液矿床的 175°C 到斑岩矿床的 400°C 以上不等。那些。微量元素的地球化学行为表明流动元素（亲湿岩浆元素）存在正异常，这些元素与金、亲花岗岩元素（主要是钨和钼）和亲铜元素有关，表明存在深部来源的金属和具有明显岩浆分异的矿化流体。