Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Charlier, B. Articles by Auwera, J. V. Search for Related Content GeoRef GeoRef Citation

Cumulate Origin and Polybaric Crystallization of Fe-Ti Oxide Ores in the Suwalki Anorthosite, Northeastern Poland

Bernard Charlier, Olivier Namur and Jean-Clair Duchesne

Department of Geology, University of Liège, 4000 Sart Tilman, Belgium

Janina Wiszniewska and Antoni Parecki

Polish Geological Institute, ul. Rakowiecka 4, 00-975 Warszawa, Poland

Jacqueline Vander Auwera

Department of Geology, University of Liège, 4000 Sart Tilman, Belgium

Corresponding author: e-mail, b.charlier{at}ulg.ac.be

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 Al₂O₃ (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.