Diamonds Discovered from High-Cr Podiform Chromitites of Bulqiza, Eastern Mirdita Ophiolite, Albania
Diamonds Discovered from High-Cr Podiform Chromitites of Bulqiza, Eastern Mirdita Ophiolite, Albania
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从阿尔巴尼亚米尔迪塔蛇绿岩东部 Bulqiza 的高铬豆状铬铁矿中发现的钻石
DOI：
10.1111/1755-6724.13111
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发表时间：
2017
影响因子：
3.3
通讯作者：
Rong He
中科院分区：
文献类型：
--
作者：
Xiong Fahui;Yang Jingsui;Robinson Paul T.;Dilek Yildirim;Milushi Ibrahim;Xu Xiangzhen;Zhou Wenda;Zhang Zhongming;Rong He
从布尔其扎铬铁矿中回收了金刚石、碳硅石、锆石、金红石、钛铁矿等多种矿物组合。目前已发现10多粒金刚石，其中大部分为浅黄色至红橙色至无色。晶粒尺寸均为100 - 300 μ m，大部分为非面体，但具有一系列形貌，包括细长、八面体和半面体变体。它们的鉴定通过拉曼光谱在1325 cm − 1和1333 cm − 1之间的特征位移得到证实，主要是在1331.51 cm − 1或1326.96 cm − 1。这项调查扩大了金刚石和莫桑石的产出，在东部米尔地塔蛇绿岩Bulqiza铬铁矿。综合布尔其扎铬铁矿的矿物学、岩石学和地球化学资料，认为其形成具有多阶段性。镁铬铁矿颗粒和可能的铬铁矿小机构形成在不同深度的上地幔，并封装超高压，高度还原和地壳矿物。一些含有镁铬铁矿及其包裹体的洋壳板片后来被捕获在俯冲带，在那里它们被拉斑玄武岩和玻泥质弧岩浆所改造，从而改变了镁铬铁矿的成分，并在熔体通道中沉积了铬铁矿。
Various combinations of diamond, moissanite, zircon, corundum, rutile and titanitehave been recovered from the Bulqiza chromitites. More than 10 grains of diamond have been recovered, most of which are pale yellow to reddish–orange to colorless. The grains are all 100–300 μm in size and mostly anhedral, but with a range of morphologies including elongated, octahedral and subhedral varieties. Their identification was confirmed by a characteristic shift in the Raman spectra between 1325 cm−1and 1333 cm−1, mostly at 1331.51 cm−1or 1326.96 cm−1. This investigation extends the occurrence of diamond and moissanite to the Bulqiza chromitites in the Eastern Mirdita Ophiolite. Integration of the mineralogical, petrological and geochemical data of the Bulqiza chromitites suggests their multi–stage formation. Magnesiochromite grains and perhaps small bodies of chromitite formed at various depths in the upper mantle, and encapsulated the ultra–high pressure, highly reduced and crustal minerals. Some oceanic crustal slabs containing the magnesiochromite and their inclusion were later trapped in suprasubduction zones, where they were modified by tholeiitic and boninitic arc magmas, thus changing the magnesiochromite compositions and depositing chromitite ores in melt channels.