Origin and geochemistry of agates in Permian volcanic rocks of the Sub-Erzgebirge basin, Saxony (Germany)
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- 作者：Jens Gö ; tzea ; goetze@mineral.tu-freiberg.de" class="auth_mail" title="E-mail the corresponding author ; Robert Mö ; ckelb ; Torsten Vennemannc ; Axel Mü ; llerd ; e
- 关键词：Agate ; Quartz ; Permian volcanics ; Saxony ; Trace elements ; Oxygen isotopes ; Cathodoluminescence
- 刊名：Chemical Geology
- 出版年：2016
- 出版时间：15 June 2016
- 年：2016
- 卷：428
- 期：Complete
- 页码：77-91
- 全文大小：3197 K
文摘
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agates in ignimbrites form during alteration processes at elevated temperatures (> 150 °C).
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specific formation processes result in high concentrations of Ge (> 90 ppm), B (46 ppm) and U (> 18 ppm) in the agates.
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normalized REE distribution patterns of the agates show strong negative Eu-anomalies, enriched HREE as well as tetrad effects.
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the microstructure of agates points to crystallization via an amorphous silica precursor under non-equilibrium conditions