Petrologic and isotope evidence for crustal source of ore-bearing Suwałki Anorthosites, Poland

The magmatic Fe-Ti-V deposit in the Suwałki Anorthosite Massif (SAM), discovered in early 60-ties, is the largest deposit of iron and titanium in Poland. The SAM belongs to bigger W-E trending Proterozoic magmatic terrane called Mazury Complex. Ilmenite and magnetite are widespread ore-minerals with subordinate quantities (1-3% of vol.) of Fe, Cu, Ni, Co sulfides in SAM rocks. Ore minerals form large ore bodies in Krzemianka, Udryń, Jeleniewo and Jezioro Okragle ore fields with total documented reserves of abount 1.5 bilion tons of titanomagnetite ores grading (in wt%) 27% Fe, 7% TiO₂ and 0,3% V₂O₅. Petrographic and geochemical study of main, trace, ultratrace elements and isotopic characteristics (E_Nd, I_sr, γos and δ ¹⁸O) of SAM rocks points towards the lower, mafic crust, close to mantle/crust boundary as the most probable source of the rocks. The Re-Os ages on magnetite and sulfides have yielded 1559±37 Ma for Krzemianka and Jezioro Okragle and 1556±94 Ma for Udryń deposit.