ABSTRACT

Metavolcanic rocks in the area north and northwest of Falun, Bergslagen, Sweden host numerous mineralisations and historic mines. The stratigraphy and formation ages of these metavolcanic rocks however remains unresolved on the local scale. This study aims to add at least some pieces to that puzzle by exploring age-constrains for the deposition of a metavolcaniclastic rock at Byngsbodberget, c. 15 km west-northwest of Falun. U-Pb SIMS analyses were conducted on zircon, from which a concordia age is calculated at 1900 ± 9 Ma and interpreted as the age of the main volcanic event that contributed material to the studied volcaniclastic rock. Based on observations of way-up indicators, this is thought to mark the lower parts of the local volcanic stratigraphy.

摘要

瑞典伯格斯拉根法伦北部和西北部地区的变质火山岩拥有众多矿化和历史悠久的矿山。然而，这些变质火山岩的地层学和形成年龄在局部尺度上仍未得到解决。这项研究旨在通过探索在 Byngsbodberget，c. 法轮西北偏西15公里。对锆石进行了 U-Pb SIMS 分析，从中计算出康科迪亚年龄为 1900 ± 9 Ma，并解释为对所研究的火山碎屑岩有贡献的主要火山事件的年龄。根据对上升指标的观察，这被认为标志着当地火山地层的下部。