Petrogenetic evolution of Late Paleozoic rhyolites of the Harvey Group, southwestern New Brunswick (Canada) hosting uranium mineralization

J. Dostal*, T. R. van Hengstum, J. G. Shellnutt, J. J. Hanley

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

4 引文 斯高帕斯(Scopus)

摘要

The 360 Ma subaerial felsic volcanic and volcaniclastic rocks of the Harvey Group form a belt about 15 km long and 3 km wide in southwestern New Brunswick (Canada) that has been correlated with parts of the Mount Pleasant caldera complex, the site of a significant polymetallic (tin, tungsten, molybdenum, indium and bismuth) deposit. The Harvey volcanic rocks are highly fractionated peraluminous within-plate F-rich rhyolites, which host uranium mineralization. The rocks were modified by late-magmatic and post-magmatic processes. A comparison of the composition of whole rocks and melt inclusions in the quartz phenocrysts shows that some trace elements, including U, were affected by the post-magmatic processes. Their flat REE patterns accompanied by distinct negative Eu anomalies are typical of highly evolved F-rich leucogranites and rhyolites. Nd isotopic ratios (ɛNd(360) = +0.6 to −1.0) are similar to those of the felsic rocks of the Mount Pleasant complex. The Harvey rhyolites were generated by extensive fractional crystallization of andesites of the Mount Pleasant caldera. The melt evolved at the apex of the magma chamber where volatile elements become concentrated. The Harvey rhyolite (with melt inclusions containing ~20 ppm U) had the potential to develop a significant U mineralization. The erupted glassy rhyolite is a favorable U source rock amendable to leaching by post-magmatic hydrothermal and meteoric water. The high Th/U ratios in the Harvey volcanic rocks compared to the low ratios in the U-rich melt inclusions is indicative of such a process.

原文英語
文章編號59
期刊Contributions to Mineralogy and Petrology
171
發行號6
DOIs
出版狀態已發佈 - 2016 六月 1

ASJC Scopus subject areas

  • 地球物理
  • 地球化學與岩石學

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