(1. 中南大學(xué) 有色金屬成礦預(yù)測教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083；
3. 湖南城市學(xué)院 城市建設(shè)系，益陽 413000)
摘 要: 采用等離子質(zhì)譜儀(ICP-MS)對三穗和黃平下寒武統(tǒng)斜坡相黑色頁巖稀土元素含量進(jìn)行分析。結(jié)果表明：稀土總量為68.28×10−6~252.00×10−6，平均含量為133.16×10−6；ΣLREE/ΣHREE的比值是2.38~5.70，輕稀土元素較重稀土元素富集。δEu=0.49~0.75，推測沉積溫度低于250 ℃；δCe= 0.34~0.85，反映巖石是在相對缺氧的海水環(huán)境條件下沉積。巖石(La/Sm)N的比值是1.77~3.31，代表有地下深部物質(zhì)加入。黑色頁巖稀土的球粒隕石配分曲線為向右傾斜，而其北美頁巖組合樣標(biāo)準(zhǔn)化曲線明顯呈近于水平或左傾。結(jié)合La/Ce和La/Yb-REE判別圖解，推斷黔東南州黑色頁巖形成于一種干燥缺氧較深淺海環(huán)境，并在形成過程中有熱液參與。
關(guān)鍵字: 稀土元素；地球化學(xué)特征；黑色頁巖；下寒武統(tǒng)；黔東南州
Lower Cambrian black shale in Southeast Qian
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
3. Department of Urban Construction, Hunan City University, Yiyang 413000, China）
Abstract:The abundances of rare earth elements (REE) of the black shale on the slope facies from Lower Cambrian in Sansui and Huangping were measured by using inductively coupled plasma mass spectrometry (ICP-MS). The results show that the total REE content is 68.28×10−6−252.00×10−6, the average one is 133.16×10−6; the ratio of ΣLREE to ΣHREE is 2.38−5.70, which shows that LREE are relatively more intensive than HREE. δEu=0.49−0.75, which shows that the deposition temperature is below 250 ℃. δCe=0.34−0.85, which reflects that a rock deposits under the condition of relatively hypoxic sea. The ratio of rock (La/Sm)N is between 1.77 and 3.31, which represents that it has added with the materials from deep resource. The chondrite normalized patterns of black shale incline to the right, the North American shale normalized REE patterns of siliceous rocks are nearly flat or left. Combined with the discrimination diagrams of La/Ce and La/Yb-REE, the black shale of Southeast Qian formed in a dry, hypoxia and shallow sea, with the participation of some hydrothermal fluids in the formation process.
Key words: rare earth element; geochemical characteristics; black shale; Lower Cambrian system; Southeast Qian
