{"title":"沉积海相磷灰石中稀土元素混合成因的可能性——以埃及Abu-Tartur高原白垩系(Campanian-Maastrichtian) Duwi组磷灰岩为例","authors":"G. El-Habaak, M. Askalany, M. Abdel-Hakeem","doi":"10.1086/705414","DOIUrl":null,"url":null,"abstract":"It is well known that the rare earth elements (REEs) incorporated in the crystal lattice of sedimentary apatite are commonly derived from ambient seawater. This study documents, for the first time, the possibility of mixed origin of apatite REEs present in the Egyptian Western Desert phosphorites, known as the Abu-Tartur phosphorites, one of the most important accumulations of sedimentary phosphorites in the Middle East and North Africa. Shale-like patterns of REEs, negative Ce anomalies, and a (La/Sm)N−(La/Yb)N binary diagram of the studied phosphorites indicate that the incorporation of REEs into apatite crystal lattices has occurred from the ambient seawater by substitution during late-stage diagenesis. The second origin is attributed to REE-bearing supergene fluids, which resulted in the occurrence of sedimentary britholite as green rims and patches containing about 14.93 wt% total REEs in places where the black phosphorites are gradually oxidized into the brown variety. For instance, the intensive chemical weathering induces the crystal lattice of carbonate fluorapatite to preferentially release Ca2+ and CO32− ion species to solution, resulting in the formation of a carbonate-depleted layer in which REEs, particularly heavy REEs, are incorporated into the preferential Ca2+ sites inside the altered apatite lattice, leading to britholite formation.","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":null,"pages":null},"PeriodicalIF":16.4000,"publicationDate":"2019-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/705414","citationCount":"3","resultStr":"{\"title\":\"Possibility of Mixed Origin of Rare Earth Elements in Sedimentary Marine Apatites: A Case Study from Phosphorites in the Cretaceous (Campanian-Maastrichtian) Duwi Formation, Abu-Tartur Plateau, Egypt\",\"authors\":\"G. El-Habaak, M. Askalany, M. Abdel-Hakeem\",\"doi\":\"10.1086/705414\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"It is well known that the rare earth elements (REEs) incorporated in the crystal lattice of sedimentary apatite are commonly derived from ambient seawater. This study documents, for the first time, the possibility of mixed origin of apatite REEs present in the Egyptian Western Desert phosphorites, known as the Abu-Tartur phosphorites, one of the most important accumulations of sedimentary phosphorites in the Middle East and North Africa. Shale-like patterns of REEs, negative Ce anomalies, and a (La/Sm)N−(La/Yb)N binary diagram of the studied phosphorites indicate that the incorporation of REEs into apatite crystal lattices has occurred from the ambient seawater by substitution during late-stage diagenesis. The second origin is attributed to REE-bearing supergene fluids, which resulted in the occurrence of sedimentary britholite as green rims and patches containing about 14.93 wt% total REEs in places where the black phosphorites are gradually oxidized into the brown variety. For instance, the intensive chemical weathering induces the crystal lattice of carbonate fluorapatite to preferentially release Ca2+ and CO32− ion species to solution, resulting in the formation of a carbonate-depleted layer in which REEs, particularly heavy REEs, are incorporated into the preferential Ca2+ sites inside the altered apatite lattice, leading to britholite formation.\",\"PeriodicalId\":1,\"journal\":{\"name\":\"Accounts of Chemical Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":16.4000,\"publicationDate\":\"2019-10-04\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1086/705414\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Accounts of Chemical Research\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1086/705414\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Accounts of Chemical Research","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1086/705414","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
Possibility of Mixed Origin of Rare Earth Elements in Sedimentary Marine Apatites: A Case Study from Phosphorites in the Cretaceous (Campanian-Maastrichtian) Duwi Formation, Abu-Tartur Plateau, Egypt
It is well known that the rare earth elements (REEs) incorporated in the crystal lattice of sedimentary apatite are commonly derived from ambient seawater. This study documents, for the first time, the possibility of mixed origin of apatite REEs present in the Egyptian Western Desert phosphorites, known as the Abu-Tartur phosphorites, one of the most important accumulations of sedimentary phosphorites in the Middle East and North Africa. Shale-like patterns of REEs, negative Ce anomalies, and a (La/Sm)N−(La/Yb)N binary diagram of the studied phosphorites indicate that the incorporation of REEs into apatite crystal lattices has occurred from the ambient seawater by substitution during late-stage diagenesis. The second origin is attributed to REE-bearing supergene fluids, which resulted in the occurrence of sedimentary britholite as green rims and patches containing about 14.93 wt% total REEs in places where the black phosphorites are gradually oxidized into the brown variety. For instance, the intensive chemical weathering induces the crystal lattice of carbonate fluorapatite to preferentially release Ca2+ and CO32− ion species to solution, resulting in the formation of a carbonate-depleted layer in which REEs, particularly heavy REEs, are incorporated into the preferential Ca2+ sites inside the altered apatite lattice, leading to britholite formation.
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.