北极阿拉斯加巴罗Elson泻湖96-7-1岩芯中稀土元素的特征及其环境意义

研究了北极阿拉斯加巴罗 Elson泻湖 96- 7- 1沉积岩芯中稀土元素的地球化学及其沉积相特征 ,以重演区域气候、环境的变化并且与全球变化相比较。结果表明 ,稀土元素总量 ∑ REE低 ,表现出北极地区以寒冻物理风化为主 ,沉积环境稀土元素含量偏低 ,其分布模式为轻稀土富集 ,Eu弱亏损 ,受沉积母岩影响显著 ,表现出亲大陆的地球化学特征。约 1 740年以前 ,陆相特征明显 ,气候干燥、寒冷 ,但是 ,1 5 5 0年左右有一暖期。1 740年后 ,出现海侵 ,巴罗气候变暖 ,1 82 1年后 ,变暖较明显 ,1 890年左右为低谷。1 90 4年持续变暖 ,1 971年左右 ,有一变冷阶段

GEOCHEMISTRY OF RARE-EARTH ELEMENTS AND ITS SIGNIFICANCE IN THE STUDY OF CLIMATIC AND ENVIRONMENTAL CHANGE IN BARROW, ARCTIC ALASKA

Geochemical characteristics of rare earth elements (REE) and sedimentary features were studied in the borehole 96 7 1 from Elson Lagoon in Barrow, Arctic Alaska. The results showed that total contents of REE(∑REE) are lower, suggesting physical weathering dominates, therefore, concentrations of rare earth elements are lower in the paleosedimentary environment. The chondrite normalized distribution patterns of REEs are characterized by light REE(LREE) enrichment and Eu depletion with terrestrial sedimentary rocks as the parent materials. In a comparison with the borecore AB-67 in Elson Lagoon, the main conclusion for climatic and environmental changes are similar: before 1740 AD, it was cold and dry with terrestrial properties, but comparatively warm around 1550 AD; after 1740 AD, it was fluctuatedly warm, and markedly warm after 1821 AD; a cold period appeared around 1890 AD; from 1904 to 1996 AD, it was continuously warm, but relatively cold around 1971 AD.