Petrological and metallogenic outlines of the Valmaggia ultaramafic pipe (Ivrea zone), NW Alps, Italy
Petrological and metallogenic outlines of the Valmaggia ultaramafic pipe (Ivrea zone), NW Alps, Italy
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意大利阿尔卑斯山西北部 Valmaggia ultaramafic 管（伊夫雷亚区）的岩石学和成矿轮廓
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发表时间：
2002
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通讯作者：
A. Tunesi
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作者：
Marco L. Fiorentinii;G. Grieco;Alfredo Ferrarioi;A. Tunesi
Valmaggia管侵入主辉长岩（基性杂岩，Ivrea-Verbano区，意大利）的最上部。与管道有关的矿体由网脉和浸染状铁镍铜硫化物矿化组成，并含有铂族元素（PGE）。管道主体大致呈椭圆形，沿WNW-ESE轴向沿着缩短，沿NNE-SSW轴向沿着延长，向WNW方向倾斜（70° ~ 90 °）。Fe-Ni-Cu硫化物矿化位于管道的内部边缘，从与主辉长岩接触到管道内部4-5米的距离。矿石矿物共生组合为硫化物（磁黄铁矿、镍黄铁矿、黄铜矿、方铅矿）、碲化物（阿尔泰矿、韦尔石、六方碲银矿）和PGM（梅伦斯基矿）。从驱动器绘制的管道横截面，以及岩相学和成矿观察结果表明，管道是同心分区的，具有均匀的核心和非均匀的边缘。根据构造证据和矿物化学，我们认为，管道主要是由一个晶体糊状物，包括相对较低的Fo橄榄石，包括buck-shot纹理的Fe-Ni硫化物和铁铝尖晶石，这是由产品的残余液体胶结。结晶从边缘向核心进行，
The Valmaggia pipe intrudes the uppermost part of the Main gabbro (Basic Complex, Ivrea-Verbano Zone, Italy). The ore body associated with the pipe consists of a stockwork and disseminated Fe-Ni-Cu sulphide mineralisation, with accessory Platinum Group Elements (PGE). The pipe consists of a roughly ellipsoidal main body, shortened along a WNW-ESE axis and elongated along a NNE-SSW axis, dipping steeply (70°-90°) towards WNW. Fe-Ni-Cu sulphide mineralisation is hosted in the internal margins of the pipe, from the contact with the host gabbro to a distance of 4-5 metres inside the pipe. The ore mineral paragenesis comprises sulfides (pyrrhotite, pentlandite, chalcopyrite, cubanite), tellurides (altaite, wehrlite, hessite) and PGM (merenskyte). Cross-sections of the pipe mapped from the drives, together with petrographic and metallogenic observations, show that the pipe is concentrically zoned, with a homogeneous core and a heterogeneous rim. On the basis of textural evidences and mineral chemistry we suggest that the pipe is primarily composed of a crystal mush comprising relatively low Fo olivine including buck-shot textured Fe-Ni sulphides and hercynite, which is cemented by products of the residual liquid. Crystallisation proceeded from the rim to the core, where residual