Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China
Leucogranites in the Lalong Dome are composed of two-mica granite, muscovite granite, albite granite, and pegmatite from core to rim. Albite granite-type Be–Nb–Ta rare metal ore bodies are hosted by albite granite and pegmatite. Based on field and petrographic observations and whole-rock geochemical...
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MDPI AG
2023-11-01
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| Online Access: | https://www.mdpi.com/2075-163X/13/11/1456 |
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| author | Jiangang Fu Guangming Li Genhou Wang Weikang Guo Suiliang Dong Yingxu Li Hai Zhang Wei Liang Yanjie Jiao |
| author_facet | Jiangang Fu Guangming Li Genhou Wang Weikang Guo Suiliang Dong Yingxu Li Hai Zhang Wei Liang Yanjie Jiao |
| author_sort | Jiangang Fu |
| collection | DOAJ |
| description | Leucogranites in the Lalong Dome are composed of two-mica granite, muscovite granite, albite granite, and pegmatite from core to rim. Albite granite-type Be–Nb–Ta rare metal ore bodies are hosted by albite granite and pegmatite. Based on field and petrographic observations and whole-rock geochemical data, highly differentiated leucogranites have been identified in the Lalong Dome. Two-mica granites, albite granites, and pegmatites yielded monazite ages of 23.6 Ma, 21.9 Ma, and 20.6 Ma, respectively. The timing of rare metal mineralization is 20.9 Ma using U–Pb columbite dating. Leucogranites have the following characteristics: high SiO<sub>2</sub> content (>73 wt.%); peraluminosity with high Al<sub>2</sub>O<sub>3</sub> content (13.6–15.2 wt.%) and A/CNK (mostly > 1.1); low TiO<sub>2</sub>, CaO, and MgO content; enrichment of Rb, Th, and U; depletion of Ba, Nb, Zr, Sr, and Ti; strong negative Eu anomalies; low εNd(t) values ranging from −12.7 to −9.77. These features show that the leucogranites are crust-derived high-potassium calc-alkaline and peraluminous S-type granites derived from muscovite dehydration melting under the water-absent condition, which possibly resulted from structural decompression responding to the activity of the South Tibetan detachment system (STDS). Geochemical data imply a continuous magma fractional crystallization process from two-mica granites through muscovite granites to albite granites and pegmatites. The differentiation index (Di) gradually strengthens from two-mica granite, muscovite granite, and albite granite to pegmatite, in which albite granite and pegmatite are highest (Di = 94). The Nb/Ta and Zr/Hf ratios of albite granite and pegmatite were less than 5 and 18, respectively, which suggests that albite granite and pegmatite belong to rare metal granites and have excellent potential for rare metal mineralization. |
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| spelling | doaj.art-5759d9565b78445a8b53bc9d1b049ceb2023-11-24T14:57:45ZengMDPI AGMinerals2075-163X2023-11-011311145610.3390/min13111456Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, ChinaJiangang Fu0Guangming Li1Genhou Wang2Weikang Guo3Suiliang Dong4Yingxu Li5Hai Zhang6Wei Liang7Yanjie Jiao8Chengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaChengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaSchool of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, ChinaChengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaChengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaChengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaChengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaChengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaChengdu Center, China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu 611230, ChinaLeucogranites in the Lalong Dome are composed of two-mica granite, muscovite granite, albite granite, and pegmatite from core to rim. Albite granite-type Be–Nb–Ta rare metal ore bodies are hosted by albite granite and pegmatite. Based on field and petrographic observations and whole-rock geochemical data, highly differentiated leucogranites have been identified in the Lalong Dome. Two-mica granites, albite granites, and pegmatites yielded monazite ages of 23.6 Ma, 21.9 Ma, and 20.6 Ma, respectively. The timing of rare metal mineralization is 20.9 Ma using U–Pb columbite dating. Leucogranites have the following characteristics: high SiO<sub>2</sub> content (>73 wt.%); peraluminosity with high Al<sub>2</sub>O<sub>3</sub> content (13.6–15.2 wt.%) and A/CNK (mostly > 1.1); low TiO<sub>2</sub>, CaO, and MgO content; enrichment of Rb, Th, and U; depletion of Ba, Nb, Zr, Sr, and Ti; strong negative Eu anomalies; low εNd(t) values ranging from −12.7 to −9.77. These features show that the leucogranites are crust-derived high-potassium calc-alkaline and peraluminous S-type granites derived from muscovite dehydration melting under the water-absent condition, which possibly resulted from structural decompression responding to the activity of the South Tibetan detachment system (STDS). Geochemical data imply a continuous magma fractional crystallization process from two-mica granites through muscovite granites to albite granites and pegmatites. The differentiation index (Di) gradually strengthens from two-mica granite, muscovite granite, and albite granite to pegmatite, in which albite granite and pegmatite are highest (Di = 94). The Nb/Ta and Zr/Hf ratios of albite granite and pegmatite were less than 5 and 18, respectively, which suggests that albite granite and pegmatite belong to rare metal granites and have excellent potential for rare metal mineralization.https://www.mdpi.com/2075-163X/13/11/1456monazite and columbite ageswhole-rock geochemistryhighly fractionated leucogranitesNb–Ta–Be rare metalsLalong DomeTethyan Himalaya |
| spellingShingle | Jiangang Fu Guangming Li Genhou Wang Weikang Guo Suiliang Dong Yingxu Li Hai Zhang Wei Liang Yanjie Jiao Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China Minerals monazite and columbite ages whole-rock geochemistry highly fractionated leucogranites Nb–Ta–Be rare metals Lalong Dome Tethyan Himalaya |
| title | Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China |
| title_full | Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China |
| title_fullStr | Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China |
| title_full_unstemmed | Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China |
| title_short | Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China |
| title_sort | geochemical evidence for genesis of nb ta be rare metal mineralization in highly fractionated leucogranites at the lalong dome tethyan himalaya china |
| topic | monazite and columbite ages whole-rock geochemistry highly fractionated leucogranites Nb–Ta–Be rare metals Lalong Dome Tethyan Himalaya |
| url | https://www.mdpi.com/2075-163X/13/11/1456 |
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