| 黔西新华大型磷矿磷块岩稀土元素地球化学及其成因意义 |
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| 引用本文：.2004.Rare Earth Elements Geochemistry and Genesis of Xinhua Large_size Phosphorite Deposit in Western Guizhou[J].Mineral Deposits,23(4):484~493 |
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| 基金项目:国家自然科学基金(编号: 40173025)、国家教育部跨世纪优秀人才培养计划基金 、国家重点基础研究发展规划(973)项目 (No. 2002CB412610) |
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| 中文摘要:利用ICP-MS测试方法系统分析了黔西织金新华磷矿磷块岩的稀土元素 组成，同时还测定了贵州遵义和湖南张家界等华南下寒武统黑色岩系中磷块岩的稀土元素含 量。结果显示：①新华磷块岩稀土元素总量(ΣREE)较高，变化较大，为164.23×10-6～1395.01×10-6-6-6-6-6200℃)、强还原热液的加入；④ 新华磷块岩中HREE相对亏损，且多数样品LaN/NdN>1，而δY>1.5，δY与δCe之间不存 在相关性，说明磷块岩遭受了较强的后期风化淋滤作用，深埋成岩作用基本未改变其REE组 成。 |
| 中文关键词:地球化学 磷块岩 稀土元素 下寒武统黑色岩系 织金 黔西 |
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| Rare Earth Elements Geochemistry and Genesis of Xinhua Large_size Phosphorite Deposit in Western Guizhou |
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| Abstract:Zhijin County in western Guizhou is one of the most important phosphorite_produc ing areas in China. To further investigate the genesis of the Xinhua phosphorite deposit in this area, the authors systematically analyzed REE composition of th is deposit by ICP_MS method. For comparison, phosphorites from Lower Cambrian bl ack rocks in such areas of South China as Zunyi of Guizhou and Zhangjiajie of Hu nan were also analyzed. Some conclusions can be reached from the analytical data : ① The Xinhua phosphorite possesses quite high and rather varied total rare ea rth elements (ΣREE), which vary between 164.23×10-6 and 1395.01×10-6, averaging 642.54×10-6, and marked differentiation between light and heavy rare earth elements. The ΣLREE/ΣHREE values vary between 5.04 and 6 .52, while the ΣREE and ΣLREE/ΣHREE values of the Zunyi and Zhangjiajie phosp horites are 156.69×10-6～637.41×10-6 (431.75×10-6 on averag e) and 3.17～6.95 (4.37 on average) respectively. ② Phosphorites from Xinhua, Z unyi and Zhangjiajie all show remarkable negative Ce anomalies. Besides, the Xin hua phosphorite possesses lower δCe, varying between 0.26 and 0.53 (0.35 on ave rage), while δCe of phosphorites from Zunyi and Zhangjiajie are 0.30～0.66, ave raging 0.47, suggesting that phosphorites are exclusively typical marine sedimen ts mainly deposited in ancient pericontinental seas, and the depositional positi on of the Xinhua phosphorite might be relatively deep. ③ Most phosphorites from Xinhua, Zunyi and Zhangjiajie possess indistinct positive Eu anomalies, with on ly a few samples assuming marked anomalies. δEu vary between 0.98 and 2.4, sugg esting that hot (>200℃) and strong reductive hydrothermal fluids might have bee n involved in the formation of phosphorites. ④ The Xinhua phosphorite is relati vely depleted in HREE, whereas LaN/NdN and δY of most samples are higher th an 1 and 1.5. Besides, there exists no correlation between δY and δCe, implyin g that phosphorites were subjected to quite strong weathering and leaching proce sses, and deep buried rock_forming processes have not remarkably changed the REE composition. ⑤ Phosphorus in the phosphorites might have mainly been derived f rom weathering and leaching of granitic continents and alkaline basalts around t he ancient pericontinental seas. |
| keywords:geochemistry, phosphorite, rare earth elements (REE), Lower Cambrian black rocks, Zhijin, western Guizhou |
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