Paragenesis of Cu-Fe ores from Ocna de Fier-Dognecea (Romania), typifying fluid plume mineralization in a proximal skarn setting
Paragenesis of Cu-Fe ores from Ocna de Fier-Dognecea (Romania), typifying fluid plume mineralization in a proximal skarn setting
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DOI：
10.1180/002646101300119457
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发表时间：
2001-06
影响因子：
2.7
通讯作者：
N. Cook;C. Ciobanu
中科院分区：
文献类型：
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作者：
N. Cook;C. Ciobanu
摘要罗马尼亚西南部巴纳特Ocna de Fier-Dognecea夕卡岩矿床富含斑铜矿和黄铜矿的铜-铁带中的微量矿物组合为这一经典的分带夕卡岩系统的成因提供了额外的限制。观察到的组合证实了一种模型，在该模型中，铜-铁带形成了系统近端的流体-烟柱根。观察到的镁镁橄榄岩夕卡岩中的微量矿物组合在~650°C的富挥发环境中结晶，证据是广泛分布的金云母、褐铁矿、钒辉石和磷灰石。因此，整个组合属于夕卡岩形成的初始阶段。在逆行阶段，长时间的冷却导致斑铜矿和黄铜矿中的微量矿物相相继出溶，尽管温度仍高于500°C。斑铜矿的特点是沿解理面和沿晶体边缘有丰富的出溶相，特别是黄铜矿和磁黄铁矿，但也有钴镍黄铁矿、方铅矿、辉铜矿、方铅矿、辉铜矿、银和银。黄铜矿赋存钴镍黄铁矿、方铅矿、方铅矿和一系列含Se和Te的矿物(方铅矿、方铅矿)，沿(但不限于)颗粒边缘。斑铜矿-黄铜矿-磁铁矿组合具有痕量相、钴、镍黄铁矿、闪锌矿和各种含Se和Te矿物，代表了不同类型矿床的共同特征组合，这些矿床形成于温度高于500°C的挥发分存在下，并以相对较低的FS₂流体为特征。
Abstract Trace mineral assemblages in the bornite- and chalcopyrite-rich Cu-Fe zone of the Ocna de Fier- Dognecea skarn deposits, Banat, SW Romania provide additional constraints on the genesis of this classic zoned skarn system. Observed assemblages substantiate a model, in which the Cu-Fe zone forms the proximal fluid-plume root of the system. Observed trace mineral assemblages in the magnesian forsterite-bearing skarns crystallized at ~650°C in a volatile-rich environment, evidenced by widespread phlogopite, ludwigite, valleriite and apatite. The entire assemblage thus belongs to the initial stage of skarn formation. Prolonged cooling led to sequential exsolution of trace mineral phases from bornite and chalcopyrite during the retrograde stage, although still at temperatures in excess of 500°C. Bornite is typified by the abundance of exsolved phases along cleavage planes and along crystal margins, notably chalcopyrite and pyrrhotite, but also cobalt pentlandite, carrollite, wittichenite, galena, mawsonite, silver and electrum. Chalcopyrite hosts cobalt pentlandite, carrollite, wittichenite, galena and a sequence of Se- and Te-bearing minerals (kawazulite, bohdanowiczite, hessite, volynskite), along, although not restricted to, grain margins. The assemblage bornite-chalcopyrite-magnetite, with the trace phases, cobalt pentlandite, carrollite, wittichenite and various Se- and Te-bearing minerals represents a characteristic assemblage common to a disparate range of deposits formed at temperatures in excess of 500°C in the presence of volatiles and typified by relatively low fS₂ fluids.