Characterization and distribution of fibrous tremolite and chrysotile minerals in the Eskişehir region of western Turkey

Abstract

AbstractBecause of widespread tremolite and chrysotile minerals in Palaeozoic-Mesozoic metamorphic and Triassic ophiolitic units, respectively, in the Eskişehir region, Turkey, there is significant potential for development of cases of mesothelioma. Such occurrences in the Eskişehir region show a positive correlation with the concentration and dimension of tremolite crystals compared with those of chrysotile crystals. A detailed assessment of the mineralogy, geochemistry and genesis of these materials has not been carried out to date; the present study was undertaken to fill that gap. The sharp diagnostic basal reflections at 8.14 Å, 3.09 Å and at 7.30 Å, 3.63 Å, well defined fibrous crystallinity, and ideal differential thermal analysis-thermal gravimetric and Raman curves suggest the development of well crystallized fibrous/acicular tremolite and chrysotile with the average structural formulae of: (Na0.07K0.03)(Ca1.68Mg0.18Mn0.01)(Fe0.42Mg4.55Ti0.01)(Si7.60Al0.24Fe0.16)O22(OH)2, and (Mg5.55Fe0.41 Mn0.006)(Si3.79Al0.13)O10(OH)8, respectively.Enrichment of light rare earth elements relative to medium rare earth elements and heavy rare earth elements in tremolite compared to that of chrysotile which exhibits no anomaly and negative anomalies for Ba, Sr, Ce, Nb, Yand Zr in the tremolite samples and chrysotile, are responses to the fractionation of feldspar, glaucophane, pyroxene and olivine under the high temperatures of hydrothermal-alteration processes during serpentinization and the high-pressure conditions of metamorphism. Based on H and O isotope data, the tremolite and chrysotile are thought to have developed from tectonically controlled magmatic and meteoric hydrothermal systems and the formation temperatures of the tremolite are higher than those of chrysotile.