Pierwsze znaleziska jadeitu w Górach Kaczawskich (Sudety)
Abstract
FIRST FINDINGS OF JADEITE IN THE KACZAWA MTS (SUDETES)
Summary
Sodic pyroxenes have been found in five exposurse of early Paleozoic quartz - normative metatrachytes in the southern Kaczawa Mts, Sudetes, NE edge of the Bohemian Massif. Their compositions range from nearly pure Jadeite (Jd 0,98, Ae 0,02) in corroded grains isolated in albite phenocrysts, to Fe3+ -rich aegirine (Jd 0,15, Ae 0,85) in tiny prisms in the matrix. This obviously relict jadeite is further evidence, apart from already reported relict glaucophane, of an early high pressure episode in the metamorphic evolution of the eastern part of the European Variscides. The PT conditions of this episode are estimated at ca. > 10 kb and 300-400°C. The age of the HP metamorphism is uncertain, though it may be assumed as pre-Carboniferous or Early Carboniferous, since the subsequent greenschist facies overprint is probably of Early Carboniferous age.
Summary
Sodic pyroxenes have been found in five exposurse of early Paleozoic quartz - normative metatrachytes in the southern Kaczawa Mts, Sudetes, NE edge of the Bohemian Massif. Their compositions range from nearly pure Jadeite (Jd 0,98, Ae 0,02) in corroded grains isolated in albite phenocrysts, to Fe3+ -rich aegirine (Jd 0,15, Ae 0,85) in tiny prisms in the matrix. This obviously relict jadeite is further evidence, apart from already reported relict glaucophane, of an early high pressure episode in the metamorphic evolution of the eastern part of the European Variscides. The PT conditions of this episode are estimated at ca. > 10 kb and 300-400°C. The age of the HP metamorphism is uncertain, though it may be assumed as pre-Carboniferous or Early Carboniferous, since the subsequent greenschist facies overprint is probably of Early Carboniferous age.