page_title: Archean felsic volcanic rocks
section_title: Limitation
hierarchical_section_title: Archean felsic volcanic rocks / Relationships between Archean felsic volcanic rocks and granitoids / Limitation
caption_attribution_description: English: Relationship between AFV and granitoids
context_page_description: Archean felsic volcanic rocks are felsic volcanic rocks that were formed in the Archean Eon. The term "felsic" means that the rocks have silica content of 62–78%. Given that the Earth formed at ~4.5 billion year ago, Archean felsic volcanic rocks provide clues on the Earth's first volcanic activities on the Earth's surface started 500 million years after the Earth's formation.
  As the Archean Earth was hotter than the present, formation of felsic volcanic rocks may differ from the modern plate tectonics.
  Archean felsic volcanic rocks are distributed only in the preserved Archean greenstone belts, where deformed sequences of volcanic-sedimentary rocks are common. Felsic volcanic rocks are rare in the early Earth and only contribute to less 20% of rocks in the Archean greenstone belts worldwide. Nonetheless, mafic volcanic rocks occupy about 50% in the greenstone belts. Thus, felsic volcanic rocks are rare members in the Archean terranes.
  Archean felsic volcanic activities commonly occur in submarine environments. The composition of Archean felsic volcanic rocks are equivalent to a spectrum between dacite and rhyolite.
context_section_description: Revealing the relationship between Archean felsic volcanic rocks and the granitoids may be difficult. It is because weathering alters the geochemical signatures of the felsic rocks above the Earth's surface. The earliest weathering record can be traced back to 3.8 Ga during Eoarchean. Potassium is enriched but sodium is depleted in these weathered felsic rocks. Altered feldspars in the rocks may result in such anomalous signatures.
caption: Fig 6. Possible relationship 2 of Archean felsic volcanic rocks and granitoids. GMS and TTG may have intruded the crust at the same time. Yet, GMS was concentrated at the upper crust and TTG at deeper intermediate crust.[9]
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