冀东司家营条带状含铁建造铁矿石铁同位素特征及其地质意义     

曹瑞明  郭香敏  崔伟  刘春来  杨立群  丁枫 《地质论评》2024,70(3):2024030001-2024030001

司家营条带状含铁建造（Banded iron formation,BIF）型铁矿床是冀东地区规模最大的铁矿床,前人对其进行了大量的年代学、岩石学和元素地球化学工作,但目前尚未对其进行Fe同位素研究。本文通过Fe同位素和主微量、稀土元素相结合的方法对司家营BIF的成矿物质来源和形成背景提出了有效制约,同时对司家营BIF的锆石U- Pb年龄数据进行补充。锆石U- Pb年代学显示,司家营BIF形成于2537~2531Ma。地球化学数据显示司家营BIF矿石主要由TFe2O3和SiO2组成,具有较低的Al2O3和TiO2含量,富集Fe重同位素（δ56Fe=0.341‰~0.525‰）;稀土元素配分模式呈现轻稀土亏损、重稀土富集的特征,具有明显的Eu、Y、La正异常,Y/Ho比率较高（Y/Ho=34.96~45.84）。这些特征表明司家营BIF是基本无碎屑物质参与的化学沉积岩,稀土元素来源于高温热液和海水的混合溶液,铁质来源于海相热液流体。司家营BIF缺乏真正的Ce负异常和Fe同位素组成均为正值指示其形成于缺氧环境。综合对比世界上其他地区太古宙BIF的Fe同位素特征,本文认为新太古代时期地球海洋含氧量逐步上升,此时海洋总体属于缺氧环境,但部分地区氧气含量较高。  相似文献   

The extraction of pigments from fresh Laminaria japonica     

杨立群  李鹏程  樊守金 《中国海洋湖沼学报》2008,26(2):193-196

The pigments in Laminariajaponica was extracted with six organic solvents and analyzed in spectroscopy analysis. The extractions conditions were screened by an orthogonal test and the quantity of extracted pigments was determined spectroscopically. The results show that： （1） among the six organic solvents, acetone was the most effective one for the extraction; （2） the optimum extraction conditions were as follows： the ratio of S/M （solvent volume/ material weight） was 30 ml/g; fresh seaweed was extracted 2 times in 2 h; （3） the average total content of pigments was 1.85 mg/g （calculated with dry L. japonica）.  相似文献