Cumulate origin and polybaric crystallization of Fe-Ti oxide ores in the Suwalki Anorthosite, Northeastern Poland

Charlier, B. and Namur, O. and Duchesne, J.-C. and Wiszniewska, J. and Parecki, A. and Auwera, J.V. (2009) Cumulate origin and polybaric crystallization of Fe-Ti oxide ores in the Suwalki Anorthosite, Northeastern Poland. Economic Geology, 104 (2). pp. 205-221. DOI 10.2113/​gsecongeo.104.2.205

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Abstract

Fe-Ti oxide ores in the Proterozoic Suwalki massif-type anorthosite, northeastern Poland, have been recognized through geophysical exploration and extensive drilling down to 2,600 m depth. The Fe-Ti oxide-rich rocks from Suwalki consist of vanadium-poor Ti-magnetite in lenses varying from the centimeter- to the kilometer-scale. Fe-Ti-rich rocks are commonly layered and have gradational contacts with the host anorthosite; they do not represent well-defined intrusions such as the major Tellnes and Lac Tio deposits. Based on petrography, modal proportions, whole-rock analyses, and liquidus phase compositions of Fe-Ti oxide ores, the sequence of crystallization is as follows: plagioclase + Ti magnetite + ilmenite, followed by orthopyroxene, then clinopyroxene, and finally apatite. The comparatively low V content (0.20-0.67 wt % V) in Ti magnetite results from relatively oxidized crystallization conditions. The diapiric emplacement of the anorthositic pluton influenced the crystallization of the Fe-Ti ores and is responsible for the crystal sorting controlled by the density contrast of liquidus phases. Polybaric crystallization of Fe-Ti oxide ores is evidenced by variable AI2O3 (ca. 1-5 wt %) content of the associated orthopyroxene. Polybarism is responsible for the appearance of Fe-Ti oxides before orthopyroxene, due to the decreasing stability field of orthopyroxene with pressure. ©2009 Society of Economic Geologists, Inc.

Item Type: Article
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Economic Geology
Volume: 104
Page Range: pp. 205-221
Identification Number: 10.2113/​gsecongeo.104.2.205
Depositing User: Sarah Humbert
Date Deposited: 23 Mar 2012 12:11
Last Modified: 23 Jul 2013 10:03
URI: http://eprints.esc.cam.ac.uk/id/eprint/2414

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