{"title":"印度支那地块西北边缘晚三叠世造山运动金矿化:老挝 Phapon 金矿的方解石 U-Pb 年龄和地球化学揭示","authors":"","doi":"10.1016/j.jseaes.2024.106350","DOIUrl":null,"url":null,"abstract":"<div><div>The Phapon orogenic gold deposit, located in the Luang Prabang (Laos)–Loei (Thailand) metallogenetic belt along the northwestern margin of the Indochina Block, is a unique vein-type deposit with calcite as the main gold-bearing mineral. Primary sulfides in gold-bearing veins in this deposit are strongly oxidized and cannot be dated. Thus, the precise age of gold mineralization has been a matter of debate and its tectonic setting remains unresolved. Previous studies confirmed that the ore-forming fluids belong to a NaCl-H<sub>2</sub>O-CO<sub>2</sub> system, but their evolution process is unclear. Based on detailed field investigation, and microscopic and CL studies, three ore-forming stages were recognized as the pre-ore calcite(Cal-1) ± quartz ± pyrite veinlets, main-ore calcite(Cal-2)-siderite-hematite-realgar ± orpiment-gold vein or veinlets, and post-ore calcite(Cal-3) vein or veinlets. Three calcite generations show comparable HREE flat patterns and Eu and Ce negative anomalies with the carbonate wallrock, suggesting the potential inheritance of some ore-forming materials. The Cal-2 has the highest REE, Mn, and Fe concentrations and the most obvious LREE-enrichment patterns than Cal-1 and Cal-3, indicating that the ore-forming fluids are more acidic and have higher temperature and more intense fluid-rock interaction at the deposit trap. The Cal-2 is intergrown with gold and was dated by LA-SF-ICP-MS and yielded a lower intercept U-Pb age of 221.6 ± 7.6 Ma, which is interpreted as the Au mineralization age for the Phapon deposit. This new age indicates that the orogenic gold mineralization event continued in the Late Triassic, after the late Permian–middle Triassic epithermal and porphyry-skarn Au mineralization events along the northwestern margin of the Indochina Block, and corresponds to the collision between the Sibumasu Terrane and the Indochina Block. A Miocene hydrothermal activity was constrained at 11.8 ± 2.4 Ma by Cal-3.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Late Triassic orogenic gold mineralization along the northwest margin of the Indochina Block: Revealed from calcite U-Pb ages and geochemistry of the Phapon gold deposit, Laos\",\"authors\":\"\",\"doi\":\"10.1016/j.jseaes.2024.106350\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>The Phapon orogenic gold deposit, located in the Luang Prabang (Laos)–Loei (Thailand) metallogenetic belt along the northwestern margin of the Indochina Block, is a unique vein-type deposit with calcite as the main gold-bearing mineral. Primary sulfides in gold-bearing veins in this deposit are strongly oxidized and cannot be dated. Thus, the precise age of gold mineralization has been a matter of debate and its tectonic setting remains unresolved. Previous studies confirmed that the ore-forming fluids belong to a NaCl-H<sub>2</sub>O-CO<sub>2</sub> system, but their evolution process is unclear. Based on detailed field investigation, and microscopic and CL studies, three ore-forming stages were recognized as the pre-ore calcite(Cal-1) ± quartz ± pyrite veinlets, main-ore calcite(Cal-2)-siderite-hematite-realgar ± orpiment-gold vein or veinlets, and post-ore calcite(Cal-3) vein or veinlets. Three calcite generations show comparable HREE flat patterns and Eu and Ce negative anomalies with the carbonate wallrock, suggesting the potential inheritance of some ore-forming materials. The Cal-2 has the highest REE, Mn, and Fe concentrations and the most obvious LREE-enrichment patterns than Cal-1 and Cal-3, indicating that the ore-forming fluids are more acidic and have higher temperature and more intense fluid-rock interaction at the deposit trap. The Cal-2 is intergrown with gold and was dated by LA-SF-ICP-MS and yielded a lower intercept U-Pb age of 221.6 ± 7.6 Ma, which is interpreted as the Au mineralization age for the Phapon deposit. This new age indicates that the orogenic gold mineralization event continued in the Late Triassic, after the late Permian–middle Triassic epithermal and porphyry-skarn Au mineralization events along the northwestern margin of the Indochina Block, and corresponds to the collision between the Sibumasu Terrane and the Indochina Block. A Miocene hydrothermal activity was constrained at 11.8 ± 2.4 Ma by Cal-3.</div></div>\",\"PeriodicalId\":50253,\"journal\":{\"name\":\"Journal of Asian Earth Sciences\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.7000,\"publicationDate\":\"2024-10-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Asian Earth Sciences\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1367912024003456\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Asian Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1367912024003456","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Late Triassic orogenic gold mineralization along the northwest margin of the Indochina Block: Revealed from calcite U-Pb ages and geochemistry of the Phapon gold deposit, Laos
The Phapon orogenic gold deposit, located in the Luang Prabang (Laos)–Loei (Thailand) metallogenetic belt along the northwestern margin of the Indochina Block, is a unique vein-type deposit with calcite as the main gold-bearing mineral. Primary sulfides in gold-bearing veins in this deposit are strongly oxidized and cannot be dated. Thus, the precise age of gold mineralization has been a matter of debate and its tectonic setting remains unresolved. Previous studies confirmed that the ore-forming fluids belong to a NaCl-H2O-CO2 system, but their evolution process is unclear. Based on detailed field investigation, and microscopic and CL studies, three ore-forming stages were recognized as the pre-ore calcite(Cal-1) ± quartz ± pyrite veinlets, main-ore calcite(Cal-2)-siderite-hematite-realgar ± orpiment-gold vein or veinlets, and post-ore calcite(Cal-3) vein or veinlets. Three calcite generations show comparable HREE flat patterns and Eu and Ce negative anomalies with the carbonate wallrock, suggesting the potential inheritance of some ore-forming materials. The Cal-2 has the highest REE, Mn, and Fe concentrations and the most obvious LREE-enrichment patterns than Cal-1 and Cal-3, indicating that the ore-forming fluids are more acidic and have higher temperature and more intense fluid-rock interaction at the deposit trap. The Cal-2 is intergrown with gold and was dated by LA-SF-ICP-MS and yielded a lower intercept U-Pb age of 221.6 ± 7.6 Ma, which is interpreted as the Au mineralization age for the Phapon deposit. This new age indicates that the orogenic gold mineralization event continued in the Late Triassic, after the late Permian–middle Triassic epithermal and porphyry-skarn Au mineralization events along the northwestern margin of the Indochina Block, and corresponds to the collision between the Sibumasu Terrane and the Indochina Block. A Miocene hydrothermal activity was constrained at 11.8 ± 2.4 Ma by Cal-3.
期刊介绍:
Journal of Asian Earth Sciences has an open access mirror journal Journal of Asian Earth Sciences: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review.
The Journal of Asian Earth Sciences is an international interdisciplinary journal devoted to all aspects of research related to the solid Earth Sciences of Asia. The Journal publishes high quality, peer-reviewed scientific papers on the regional geology, tectonics, geochemistry and geophysics of Asia. It will be devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be included. Papers must have international appeal and should present work of more than local significance.
The scope includes deep processes of the Asian continent and its adjacent oceans; seismology and earthquakes; orogeny, magmatism, metamorphism and volcanism; growth, deformation and destruction of the Asian crust; crust-mantle interaction; evolution of life (early life, biostratigraphy, biogeography and mass-extinction); fluids, fluxes and reservoirs of mineral and energy resources; surface processes (weathering, erosion, transport and deposition of sediments) and resulting geomorphology; and the response of the Earth to global climate change as viewed within the Asian continent and surrounding oceans.