Wstępne rozpoznanie obwódek cyrkonowo-hafnowych wokół minerałów kruszcowych w złożach Fe-Ti-V w suwalskim masywie anortozytowym (północno-wschodnia Polska)
Abstract
Initial recognition of zirconium-hafnium rims around ore minerals in the Fe-Ti-V deposits, Suwałki Anorthosite Massif (NE Poland).
A b s t r a c t. Zirconium-hafnium rims were discovered and described for the first time within the Suwalki Anorthosite Massif (SAM). They are observed at boundaries of Fe-Ti oxides ilmenite, hematitoilmenite and titanomagnetite with plagioclases. The most frequent forms reach 80–250 m in length and 4–30 m in width. These are narrow rims covering even up to 70% ore mineral grains. The most spectacular forms were “blown candle flame” structures. Their average width ranges from 20 to 45 m and the length exceeds 350 m in . Chemical composition analysis was carried out on the largest clusters of zircon crystals/rims which show high local enrichment in Hf (0.5–0.8% by weight). The boundaries of these crystals are cracked and blurry. This may suggest their participation in later fluids inflow processes within the rocks. The enrichment in hafnium content in zircon grains, is related to significant reduction in the amount of Th, U and Pb and increased amountsof Ti and Fe in zircon rims. A large variety of forms and variability of their chemical composition point to a complex physical chemical orgin process.
A b s t r a c t. Zirconium-hafnium rims were discovered and described for the first time within the Suwalki Anorthosite Massif (SAM). They are observed at boundaries of Fe-Ti oxides ilmenite, hematitoilmenite and titanomagnetite with plagioclases. The most frequent forms reach 80–250 m in length and 4–30 m in width. These are narrow rims covering even up to 70% ore mineral grains. The most spectacular forms were “blown candle flame” structures. Their average width ranges from 20 to 45 m and the length exceeds 350 m in . Chemical composition analysis was carried out on the largest clusters of zircon crystals/rims which show high local enrichment in Hf (0.5–0.8% by weight). The boundaries of these crystals are cracked and blurry. This may suggest their participation in later fluids inflow processes within the rocks. The enrichment in hafnium content in zircon grains, is related to significant reduction in the amount of Th, U and Pb and increased amountsof Ti and Fe in zircon rims. A large variety of forms and variability of their chemical composition point to a complex physical chemical orgin process.