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  • 館藏編號:NTUG010-T700161
  • 題名:岩石地球化學及地球的演化
  • 作者:孫賢鉥
  • 藏品形式:稿本
  • 尺寸:297X210(mm)
  • 簡述:第十四講 從地化的眼光看地殼的形成和發展
  • 內容:

    7. In areas with 2.7 b.y. Archaean and young rocks, REE patterns for shales show distinctive change across the Archaean-proterozoic boundary. The Archaean shale REE pattern could be explained by mixing of tholeiites and tonalites in the greenstone belt. The post-Archaean shales have higher total REE abundances and about 30% negative Eu anomaly. They could be explained by erosion of acid volcanics of crustal origin with residual feldspar holding back some Eu during partial melting. Most proterozoic acid volcanic have similar REE patterns to the post-Archaean shale suggesting ensialic melting origin. Their source rocks could be of Archaean age (but need not be). If this is correct, one would expect extensive distribution of exposed Archaean underneath proterozoic terrains.