Chuanrong Nie , Lu Xiang , Zhengqi Xu , Chongxiao Dai
{"title":"康店和罗辛-胡赛布含铀白垩系岩石主要元素和痕量元素组成的比较","authors":"Chuanrong Nie , Lu Xiang , Zhengqi Xu , Chongxiao Dai","doi":"10.1016/j.oreoa.2023.100038","DOIUrl":null,"url":null,"abstract":"<div><p><span>The Rössing-Husaib area is well-known for its low-grade and large-reserve U deposits hosted by leucogranites. The leucocratic dykes in the Kang-dian area of China resemble the Rössing-Husaib uraniferous leucogranites in occurrences and mineral assemblages, however, it remains disputable if the Rössing-Husaib and Kang-dian leucocratic rocks have consistent U-mineralizing processes. A comparison of the major and trace element data of the leucocratic rocks from both areas may help to better understand the ore-forming mechanisms and provide implications for exploration in the Kang-dian area. The positive correlation between Rb and P</span><sub>2</sub>O<sub>5</sub> contents for the Rössing leucogranite samples is typical of S-type granitoids in spite of the low A/CNK ratios (∼1.0). The Rössing-Husaib uraniferous leucogranites are generally rich in K<sub>2</sub>O and Rb, and have high Rb/Sr and Rb/Ba ratios. In contrast, the Kang-dian leucocratic dykes have lower K<sub>2</sub>O and Rb contents, and lower Rb/Sr and Rb/Ba ratios, suggesting a clay-poor source. The U contents of the Rössing-Husaib and Kang-dian dyke samples are positively correlated with TiO<sub>2</sub><span><span><span> contents, but show no correlation with Rb/Sr ratios, which is inconsistent with fractional crystallization. Low-degree partial melting of a U-rich </span>protolith may account for primary U enrichment in the leucocratic rocks. The variable major- and trace-element compositions of the Kang-dian dyke samples may reflect wall-rock assimilation and/or alteration to varying degrees, which further enhanced U enrichment. Relatively low Th/U ratios (∼0.1) favored the final crystallization of </span>uraninite<span><span>. The uraniferous leucogranites in the Kang-dian and Rössing-Husaib areas are commonly undeformed and emplaced along regional large faults and/or domes at the late stage of orogeny. We propose that decompression and uplift of basement rocks facilitated the generation of uraniferous melts, and regional large faults provided a pathway for the ascent of leucocratic </span>magma from depth.</span></span></p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"16 ","pages":"Article 100038"},"PeriodicalIF":0.0000,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Comparison of the major- and trace-element compositions of the Kang-dian and Rössing-Husaib uraniferous leucocratic rocks\",\"authors\":\"Chuanrong Nie , Lu Xiang , Zhengqi Xu , Chongxiao Dai\",\"doi\":\"10.1016/j.oreoa.2023.100038\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p><span>The Rössing-Husaib area is well-known for its low-grade and large-reserve U deposits hosted by leucogranites. The leucocratic dykes in the Kang-dian area of China resemble the Rössing-Husaib uraniferous leucogranites in occurrences and mineral assemblages, however, it remains disputable if the Rössing-Husaib and Kang-dian leucocratic rocks have consistent U-mineralizing processes. A comparison of the major and trace element data of the leucocratic rocks from both areas may help to better understand the ore-forming mechanisms and provide implications for exploration in the Kang-dian area. The positive correlation between Rb and P</span><sub>2</sub>O<sub>5</sub> contents for the Rössing leucogranite samples is typical of S-type granitoids in spite of the low A/CNK ratios (∼1.0). The Rössing-Husaib uraniferous leucogranites are generally rich in K<sub>2</sub>O and Rb, and have high Rb/Sr and Rb/Ba ratios. In contrast, the Kang-dian leucocratic dykes have lower K<sub>2</sub>O and Rb contents, and lower Rb/Sr and Rb/Ba ratios, suggesting a clay-poor source. The U contents of the Rössing-Husaib and Kang-dian dyke samples are positively correlated with TiO<sub>2</sub><span><span><span> contents, but show no correlation with Rb/Sr ratios, which is inconsistent with fractional crystallization. Low-degree partial melting of a U-rich </span>protolith may account for primary U enrichment in the leucocratic rocks. The variable major- and trace-element compositions of the Kang-dian dyke samples may reflect wall-rock assimilation and/or alteration to varying degrees, which further enhanced U enrichment. Relatively low Th/U ratios (∼0.1) favored the final crystallization of </span>uraninite<span><span>. The uraniferous leucogranites in the Kang-dian and Rössing-Husaib areas are commonly undeformed and emplaced along regional large faults and/or domes at the late stage of orogeny. We propose that decompression and uplift of basement rocks facilitated the generation of uraniferous melts, and regional large faults provided a pathway for the ascent of leucocratic </span>magma from depth.</span></span></p></div>\",\"PeriodicalId\":100993,\"journal\":{\"name\":\"Ore and Energy Resource Geology\",\"volume\":\"16 \",\"pages\":\"Article 100038\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2023-12-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Ore and Energy Resource Geology\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S2666261223000202\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ore and Energy Resource Geology","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2666261223000202","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Comparison of the major- and trace-element compositions of the Kang-dian and Rössing-Husaib uraniferous leucocratic rocks
The Rössing-Husaib area is well-known for its low-grade and large-reserve U deposits hosted by leucogranites. The leucocratic dykes in the Kang-dian area of China resemble the Rössing-Husaib uraniferous leucogranites in occurrences and mineral assemblages, however, it remains disputable if the Rössing-Husaib and Kang-dian leucocratic rocks have consistent U-mineralizing processes. A comparison of the major and trace element data of the leucocratic rocks from both areas may help to better understand the ore-forming mechanisms and provide implications for exploration in the Kang-dian area. The positive correlation between Rb and P2O5 contents for the Rössing leucogranite samples is typical of S-type granitoids in spite of the low A/CNK ratios (∼1.0). The Rössing-Husaib uraniferous leucogranites are generally rich in K2O and Rb, and have high Rb/Sr and Rb/Ba ratios. In contrast, the Kang-dian leucocratic dykes have lower K2O and Rb contents, and lower Rb/Sr and Rb/Ba ratios, suggesting a clay-poor source. The U contents of the Rössing-Husaib and Kang-dian dyke samples are positively correlated with TiO2 contents, but show no correlation with Rb/Sr ratios, which is inconsistent with fractional crystallization. Low-degree partial melting of a U-rich protolith may account for primary U enrichment in the leucocratic rocks. The variable major- and trace-element compositions of the Kang-dian dyke samples may reflect wall-rock assimilation and/or alteration to varying degrees, which further enhanced U enrichment. Relatively low Th/U ratios (∼0.1) favored the final crystallization of uraninite. The uraniferous leucogranites in the Kang-dian and Rössing-Husaib areas are commonly undeformed and emplaced along regional large faults and/or domes at the late stage of orogeny. We propose that decompression and uplift of basement rocks facilitated the generation of uraniferous melts, and regional large faults provided a pathway for the ascent of leucocratic magma from depth.