Mineralogy, zircon <scp>U</scp>–<scp>P</scp>b–<scp>H</scp>f isotopes, and whole‐rock geochemistry of <scp>L</scp>ate <scp>C</scp>retaceous–<scp>E</scp>ocene granites from the <scp>T</scp>engchong terrane, western <scp>Y</scp>unnan, <scp>C</scp>hina: <scp>R</scp>ecord of the closure of the <scp>N</scp>eo‐<scp>T</scp>ethyan <scp>O</scp>cean
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<jats:p>New data from mineralogy, geochemistry, zircon U–Pb dating, and Hf isotopes have revealed Late Cretaceous to Eocene magmatic intrusions in the Tengchong terrane and constrained the origin, tectonic setting, and characteristics of tin‐bearing and barren granitoids. We divide the studied granitoids into two groups: (a) the Late Cretaceous Zhinaxiang (70 Ma) and Early Paleocene Dazhupeng (65 Ma) S‐type barren granites and (b) the Eocene Lailishan A<jats:sub>2</jats:sub>‐type tin‐bearing granite (50 Ma). All these granitoids display Si‐ and K‐rich and calc‐alkaline characteristics and have similar chondrite‐normalized rare earth element patterns. However, geochemical differences do exist between the two groups of granites. The Zhinaxiang and Dazhupeng S‐type granites are slightly peraluminous, enriched in large‐ion lithophile elements (e.g., Rb and K), and depleted in high‐field‐strength elements (e.g., Nb, Ta, Zr, and Hf), whereas the Lailishan A<jats:sub>2</jats:sub>‐type granite has higher <jats:sup>T</jats:sup>Fe<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, high‐field‐strength element content, and Ga/Al ratios. The geochemical and Hf isotopic data indicate that the granites in this study were generated by partial melting of Paleoproterozoic metasedimentary rocks. Due to the subduction of the Neo‐Tethyan Ocean beneath the Eurasian plate, the Zhinaxiang and Dazhupeng S‐type granites were formed in a thickened‐crustal environment, whereas the Lailishan A<jats:sub>2</jats:sub>‐type granite was emplaced in a post‐collisional extensional setting attributed to slab break‐off. By comparison between tin‐bearing and barren granites, we propose that the Sn mineralization could be related to relatively high‐temperature and low‐pressure crystallization conditions.</jats:p>
収録刊行物
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- Geological Journal
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Geological Journal 53 1423-1441, 2017-07-27
Wiley
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詳細情報 詳細情報について
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- CRID
- 1870302168009197696
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- DOI
- 10.1002/gj.2964
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- ISSN
- 10991034
- 00721050
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- データソース種別
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- OpenAIRE