THE METAMORPHISM OF PYRITE AND PYRITIC ORES - AN OVERVIEW
THE METAMORPHISM OF PYRITE AND PYRITIC ORES - AN OVERVIEW
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DOI：
10.1180/minmag.1993.057.386.02
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发表时间：
1993-03-01
影响因子：
2.7
通讯作者：
VOKES, FM
中科院分区：
文献类型：
--
作者：
CRAIG, JR;VOKES, FM
黄铁矿是地球表层岩石中分布最广、含量最丰富的硫化物矿物，通常构成矿床中的主要不透明相。因此，了解黄铁矿的行为及其与共生相的关系，在变质过程中的黄铁矿含岩石是至关重要的解释其成因和沉积后的历史。变质作用通常导致原生结构的消失，但最近的研究表明，黄铁矿的耐火性质使其能够保留一些变质前的结构。黄铁矿矿石中的磁黄铁矿常被认为是黄铁矿在变质过程中的分解。现在很清楚，磁黄铁矿可以是原生的，并且磁黄铁矿与黄铁矿的存在提供了一种缓冲，在变质作用期间限制硫的活性。黄铁矿-磁黄铁矿的比例在变质过程中发生变化，因为逆热导致硫从黄铁矿中释放形成磁黄铁矿，并且逆冷允许黄铁矿在磁黄铁矿释放硫时再生长。黄铁矿的逆生长可能包裹了早期阶段形成的结构，并保留了逆生长事件的证据。硫同位素交换的黄铁矿与磁黄铁矿往往均匀化阶段在退变质期，但越来越重的硫在黄铁矿中留下的签名。
Pyrite, the most widespread and abundant of sulphide minerals in the Earth's surficial rocks, commonly constitutes the primary opaque phase in ore deposits. Consequently, an understanding of the behaviour of pyrite and its relationships with coexisting phases during the metamorphism of pyrite-bearing rocks is vital to the interpretation of their genesis and post-depositional history. Metamorphism is commonly responsible for the obliteration of primary textures but recent studies have shown that the refractory nature of pyrite allows it to preserve some pre-metamorphic textures. Pyrrhotite in pyritic ores has often been attributed to the breakdown of pyrite during metamorphism. It is now clear that pyrrhotite can be primary and that the presence of pyrrhotite with the pyrite provides a buffer that constrains sulphur activity during metamorphism. Pyrite-pyrrhotite ratios change during metamorphism as prograde heating results in sulphur release from pyrite to form pyrrhotite and as retrograde cooling permits re-growth of pyrite as the pyrrhotite releases sulphur. Retrograde growth of pyrite may encapsulate textures developed during earlier stages as well as preserve evidence of retrograde events. Sulphur isotope exchange of pyrite with pyrrhotite tends to homogenise phases during prograde periods but leaves signatures of increasingly heavy sulphur in the pyrite during retrograde periods.