{"title":"巴西东南部poos de Caldas碱性地块绿质岩矿物组合研究","authors":"Celso de Barros Gomes, A. A. Azzi, Daniel Atencio","doi":"10.1590/2317-4889202320220076","DOIUrl":null,"url":null,"abstract":"Abstract This study revises the early-magmatic, late-magmatic, and hydrothermal mineral assemblages occurring in rocks of agpaitic affinity, mainly represented by nepheline syenites and phonolites, from the Poços de Caldas alkaline massif. Mostly composed of different types of silicates, these rocks include rare minerals of of distinct groups, such as sulfides, oxides, carbonates, phosphates, sulfates, niobates, and notably halides, with villiaumite (NaF) as an important phase indicative of extreme alkali enrichment. Hydrothermal alteration products of nepheline and alkali feldspar typically consist of feldspathoids and zeolites. The rare minerals are of varied origin, from magmatic crystallization to hydrothermal and weathering processes. In general, they tend to occur interstitially or form euhedral crystals, especially when filling cavities or growing out from their walls. Petrological conditions involving the formation of the agpaitic rocks and their mineral assemblages are discussed.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"49 1","pages":""},"PeriodicalIF":1.3000,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A review of mineral assemblages of agpaitic rocks from the Poços de Caldas alkaline massif, southeastern Brazil\",\"authors\":\"Celso de Barros Gomes, A. A. Azzi, Daniel Atencio\",\"doi\":\"10.1590/2317-4889202320220076\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Abstract This study revises the early-magmatic, late-magmatic, and hydrothermal mineral assemblages occurring in rocks of agpaitic affinity, mainly represented by nepheline syenites and phonolites, from the Poços de Caldas alkaline massif. Mostly composed of different types of silicates, these rocks include rare minerals of of distinct groups, such as sulfides, oxides, carbonates, phosphates, sulfates, niobates, and notably halides, with villiaumite (NaF) as an important phase indicative of extreme alkali enrichment. Hydrothermal alteration products of nepheline and alkali feldspar typically consist of feldspathoids and zeolites. The rare minerals are of varied origin, from magmatic crystallization to hydrothermal and weathering processes. In general, they tend to occur interstitially or form euhedral crystals, especially when filling cavities or growing out from their walls. Petrological conditions involving the formation of the agpaitic rocks and their mineral assemblages are discussed.\",\"PeriodicalId\":9221,\"journal\":{\"name\":\"Brazilian Journal of Geology\",\"volume\":\"49 1\",\"pages\":\"\"},\"PeriodicalIF\":1.3000,\"publicationDate\":\"2023-09-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Brazilian Journal of Geology\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1590/2317-4889202320220076\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Brazilian Journal of Geology","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1590/2317-4889202320220076","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
A review of mineral assemblages of agpaitic rocks from the Poços de Caldas alkaline massif, southeastern Brazil
Abstract This study revises the early-magmatic, late-magmatic, and hydrothermal mineral assemblages occurring in rocks of agpaitic affinity, mainly represented by nepheline syenites and phonolites, from the Poços de Caldas alkaline massif. Mostly composed of different types of silicates, these rocks include rare minerals of of distinct groups, such as sulfides, oxides, carbonates, phosphates, sulfates, niobates, and notably halides, with villiaumite (NaF) as an important phase indicative of extreme alkali enrichment. Hydrothermal alteration products of nepheline and alkali feldspar typically consist of feldspathoids and zeolites. The rare minerals are of varied origin, from magmatic crystallization to hydrothermal and weathering processes. In general, they tend to occur interstitially or form euhedral crystals, especially when filling cavities or growing out from their walls. Petrological conditions involving the formation of the agpaitic rocks and their mineral assemblages are discussed.
期刊介绍:
The Brazilian Journal of Geology (BJG) is a quarterly journal published by the Brazilian Geological Society with an electronic open access version that provides an in-ternacional medium for the publication of original scientific work of broad interest concerned with all aspects of the earth sciences in Brazil, South America, and Antarctica, in-cluding oceanic regions adjacent to these regions. The BJG publishes papers with a regional appeal and more than local significance in the fields of mineralogy, petrology, geochemistry, paleontology, sedimentology, stratigraphy, structural geology, tectonics, neotectonics, geophysics applied to geology, volcanology, metallogeny and mineral deposits, marine geology, glaciology, paleoclimatology, geochronology, biostratigraphy, engineering geology, hydrogeology, geological hazards and remote sensing, providing a niche for interdisciplinary work on regional geology and Earth history.
The BJG publishes articles (including review articles), rapid communications, articles with accelerated review processes, editorials, and discussions (brief, objective and concise comments on recent papers published in BJG with replies by authors).
Manuscripts must be written in English. Companion papers will not be accepted.