Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan Plateau
Lacustrine strata-bound magnesite deposits associated with Alpine-type ultramafic rocks are hydrothermal in origin. The magnesite ores of the Kamado deposit are unconformably underlain by mid-Jurassic marine carbonate and ultramafic rocks of the Bangong-Nujiang ophiolite suite and are in fault conta...
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MDPI AG
2023-12-01
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| Online Access: | https://www.mdpi.com/2075-163X/14/1/45 |
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| author | Xuhui Yu Guyue Hu Yuchuan Chen Ying Xu Han Chen Denghong Wang Fan Huang Shuisheng You Haiyong Liu Liang He Yubin Li |
| author_facet | Xuhui Yu Guyue Hu Yuchuan Chen Ying Xu Han Chen Denghong Wang Fan Huang Shuisheng You Haiyong Liu Liang He Yubin Li |
| author_sort | Xuhui Yu |
| collection | DOAJ |
| description | Lacustrine strata-bound magnesite deposits associated with Alpine-type ultramafic rocks are hydrothermal in origin. The magnesite ores of the Kamado deposit are unconformably underlain by mid-Jurassic marine carbonate and ultramafic rocks of the Bangong-Nujiang ophiolite suite and are in fault contact with hanging wall rocks composed of siliceous sinter. Three types of cryptocrystalline magnesite ores can be identified in Kamado: (1) strata-bound massive magnesites, representing the main ore type in the upper part; (2) banded ores in the lower part; and (3) some vein and stockwork ore in the ultramafic wall rocks. Integrated scanning electron microscopy, C–O isotope analysis, and geochemical analyses were carried out on the Kamado deposit. The results indicate that: (1) the orebody is composed of magnesite, with accessory minerals of aragonite, opal, and chromite; (2) the siliceous sinter and relatively high B (32.0–68.1 ppm) and Li (14.7–23.4 ppm) contents of the magnesite ores reflect long-term spring activity in Kamado; (3) the light carbon (<i>δ</i><sup>13</sup>C<sub>V-PDB</sub>: −4.7 ± 0.3‰ to −4.1 ± 0.6‰) and oxygen isotopic compositions (<i>δ</i><sup>18</sup>O<sub>V-SMOW</sub>: +12.3 ± 0.3 to +16.3 ± 0.1‰) of the stockwork ores in the foot wall rocks indicated that the carbon in fractures in the ultramafic rocks is from a mixture of marine carbonate and oxidized organic-rich sedimentary rocks, reflecting a typical “Kraubath-type” magnesite deposit; and (4) the relatively heavy carbon isotopic (<i>δ</i><sup>13</sup>C<sub>V-PDB</sub>: +8.7 ± 0.4‰ to +8.8 ± 0.3‰) composition of the banded magnesite ores in the lower segment may have formed from heavy CO<sub>2</sub> generated by anaerobic fermentation in the lakebed. Additionally, the carbon isotopic (<i>δ</i><sup>13</sup>C<sub>V-PDB</sub>: +7.3 ± 0.3‰ to +7.7 ± 0.7‰) composition of the massive magnesite ores in the upper segment indicates a decline in the participation of anaerobic fermentation. As this economically valuable deposit is of the strata-bound massive ore type, Kamado can be classified as a lacustrine hydrothermal-sedimentary magnesite deposit, formed by continuous spring activities under salt lakes on the Tibetan Plateau, with the Mg mainly being contributed by nearby ultramafic rocks and the carbon mainly being sourced from atmosphere-lake water exchange, with minor amounts from marine carbonate strata. |
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| spelling | doaj.art-40cbf1e7851e42a483b26bb721c77aeb2024-01-26T17:52:20ZengMDPI AGMinerals2075-163X2023-12-011414510.3390/min14010045Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan PlateauXuhui Yu0Guyue Hu1Yuchuan Chen2Ying Xu3Han Chen4Denghong Wang5Fan Huang6Shuisheng You7Haiyong Liu8Liang He9Yubin Li10College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, ChinaMNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaMNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaInstitute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Chengdu 610041, ChinaSichuan Earthquake Administration, Chengdu 610041, ChinaMNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaMNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaSichuan Geology and Mineral Bureau Regional Geological Survey Team, Chengdu 610213, ChinaGeological Survey of Tibet Autonomous Region, Lhasa 850000, ChinaCollege of Earth Sciences, Chengdu University of Technology, Chengdu 610059, ChinaCollege of Engineering, Tibet University, Lhasa 850000, ChinaLacustrine strata-bound magnesite deposits associated with Alpine-type ultramafic rocks are hydrothermal in origin. The magnesite ores of the Kamado deposit are unconformably underlain by mid-Jurassic marine carbonate and ultramafic rocks of the Bangong-Nujiang ophiolite suite and are in fault contact with hanging wall rocks composed of siliceous sinter. Three types of cryptocrystalline magnesite ores can be identified in Kamado: (1) strata-bound massive magnesites, representing the main ore type in the upper part; (2) banded ores in the lower part; and (3) some vein and stockwork ore in the ultramafic wall rocks. Integrated scanning electron microscopy, C–O isotope analysis, and geochemical analyses were carried out on the Kamado deposit. The results indicate that: (1) the orebody is composed of magnesite, with accessory minerals of aragonite, opal, and chromite; (2) the siliceous sinter and relatively high B (32.0–68.1 ppm) and Li (14.7–23.4 ppm) contents of the magnesite ores reflect long-term spring activity in Kamado; (3) the light carbon (<i>δ</i><sup>13</sup>C<sub>V-PDB</sub>: −4.7 ± 0.3‰ to −4.1 ± 0.6‰) and oxygen isotopic compositions (<i>δ</i><sup>18</sup>O<sub>V-SMOW</sub>: +12.3 ± 0.3 to +16.3 ± 0.1‰) of the stockwork ores in the foot wall rocks indicated that the carbon in fractures in the ultramafic rocks is from a mixture of marine carbonate and oxidized organic-rich sedimentary rocks, reflecting a typical “Kraubath-type” magnesite deposit; and (4) the relatively heavy carbon isotopic (<i>δ</i><sup>13</sup>C<sub>V-PDB</sub>: +8.7 ± 0.4‰ to +8.8 ± 0.3‰) composition of the banded magnesite ores in the lower segment may have formed from heavy CO<sub>2</sub> generated by anaerobic fermentation in the lakebed. Additionally, the carbon isotopic (<i>δ</i><sup>13</sup>C<sub>V-PDB</sub>: +7.3 ± 0.3‰ to +7.7 ± 0.7‰) composition of the massive magnesite ores in the upper segment indicates a decline in the participation of anaerobic fermentation. As this economically valuable deposit is of the strata-bound massive ore type, Kamado can be classified as a lacustrine hydrothermal-sedimentary magnesite deposit, formed by continuous spring activities under salt lakes on the Tibetan Plateau, with the Mg mainly being contributed by nearby ultramafic rocks and the carbon mainly being sourced from atmosphere-lake water exchange, with minor amounts from marine carbonate strata.https://www.mdpi.com/2075-163X/14/1/45lacustrine hydrothermal-sedimentary mineralizationultramafic rockssuture zonegeochemistrycarbon isotopesoxygen isotopes |
| spellingShingle | Xuhui Yu Guyue Hu Yuchuan Chen Ying Xu Han Chen Denghong Wang Fan Huang Shuisheng You Haiyong Liu Liang He Yubin Li Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan Plateau Minerals lacustrine hydrothermal-sedimentary mineralization ultramafic rocks suture zone geochemistry carbon isotopes oxygen isotopes |
| title | Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan Plateau |
| title_full | Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan Plateau |
| title_fullStr | Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan Plateau |
| title_full_unstemmed | Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan Plateau |
| title_short | Genesis of the Large-Scale Kamado Magnesite Deposit on the Tibetan Plateau |
| title_sort | genesis of the large scale kamado magnesite deposit on the tibetan plateau |
| topic | lacustrine hydrothermal-sedimentary mineralization ultramafic rocks suture zone geochemistry carbon isotopes oxygen isotopes |
| url | https://www.mdpi.com/2075-163X/14/1/45 |
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