International Geologiical Congress - Oslo 2008

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MPM-13 Inclusions in minerals

 

Kumdykolite, an orthorhombic polymorph of albite, from the Kokchetav ultrahigh-pressure massif, Kazakhstan

 

Pouyan Shen, Institute of Materials Science and Engineering (Taiwan)
Shyh-lung Hwang, Institute of Materials Science and Engineering (Taiwan)
Hao-tsu Chu, Central Geological Survey (Taiwan)
Tzen-fu Yui, Institute of Earth Sciences, Academia Sinica (Taiwan)
J.G. Liou, Department of Geological and Environmental Sciences, Stanford University (United States)
Nikolay V. Sobolev, Institute of Mineralogy and Petrology, Siberian Branch of Russian Academy of Sciences (Russian Federation)
 

 

Kumdykolite, an orthorhombic polymorph of albite, was first identified by analytical electron microscopy in association with diopside, quartz/cristobalite, phengite/phlogopite, an un-identified aluminosilicate, calcic amphibole, dolomite, calcite, or talc as micron-scale mineral inclusions in omphacite of eclogite from the Kumdy Kol, Kokchetav ultrahigh-pressure massif, northern Kazakhstan. The unit cell parameters of kumdykolite were determined to be a = 8.24(1) Å, b = 8.65(1) Å, and c = 4.84(1) Å (V = 346.17 Å3, Z = 2).

Its space group could be either P2nn or Pmnn. Analogous to svyatoslavite, which is an orthorhombic metastable polymorph of anorthite, kumdykolite is also presumed to be a metastable phase formed at high temperatures with rapid cooling and in the absence of water. A tentative scenario is further postulated that the formation of kumdykolite may result from infiltrated melt-omphacite interaction when the Kokchetav massif exhumed from mantle depths to the base of the crust.

 

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