Composition and Assemblage Characteristics of Magnetic Minerals in Layer S_(5-1) of Xifeng and Duanjiapo Sections  

作　　者：贾蓉芬 彭先芝 周正 刘德汉 王冠鑫 王德强 

机构地区：[1]Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China,(State Key Lab. of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 [2]Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

出　　处：《Chinese Journal Of Geochemistry》2004年第3期197-206,共10页中国地球化学学报

基　　金：ThisresearchprojectwasfinanciallysupportedjointlybytheNationalNaturalScienceFoundationofChina (GrantNo .4 0 0 730 2 9)andtheDirector’sFoundationoftheGuangzhouInstituteofGeochemistry ,ChineseAcademyofSciences (No .A0 5 0 2 0 5 0 1 4 )

摘　　要：Relatively strongly magnetic fine components (<30μm, XS-4J and DS-4J) which are most environmentally sensitive were separated from layer S-{5-1} in the Xifeng and Duanjiapo loess sections and analyzed by MPV-3 for their morphometric characteristics and reflectance, SEM-ESD for their element contents and XRD for their mineral phases, respectively. The results showed that minerals in both samples are dominated by detrial Fe-Ti oxides of aeolian origin. In sample XS-4J the reflectance and iron contents of magnetic minerals are usually high. In addition to magnetite (Fe-3O-4), maghemite (γFe-2O-3) and hematite (Fe-2O-3), some Fe-high oxide ({72.25 wt%}-{86.67 wt%}), ilmenite (FeTiO-3), and magnetite-ulvspinel were also detected. In sample DS-4J obvious negative linear correlations were found between Ti and Fe, and the contents of Mn, Si, Al and Ca are usually high and the minerals are dominated by magnetite (maghemite), goethite (FeOOH) and limonite (containing Si and OH). In addition, the signs of corrosion of magnetic minerals and newly crystallized magnetite (maghemite) were recognized. Differences in the composition and assemblage characteristics of magnetite minerals between XS and DS reflect significant differences in source rocks and preserving conditions.Relatively strongly magnetic fine components (<30μm, XS-4J and DS-4J) which are most environmentally sensitive were separated from layer S-{5-1} in the Xifeng and Duanjiapo loess sections and analyzed by MPV-3 for their morphometric characteristics and reflectance, SEM-ESD for their element contents and XRD for their mineral phases, respectively. The results showed that minerals in both samples are dominated by detrial Fe-Ti oxides of aeolian origin. In sample XS-4J the reflectance and iron contents of magnetic minerals are usually high. In addition to magnetite (Fe-3O-4), maghemite (γFe-2O-3) and hematite (Fe-2O-3), some Fe-high oxide ({72.25 wt%}-{86.67 wt%}), ilmenite (FeTiO-3), and magnetite-ulvspinel were also detected. In sample DS-4J obvious negative linear correlations were found between Ti and Fe, and the contents of Mn, Si, Al and Ca are usually high and the minerals are dominated by magnetite (maghemite), goethite (FeOOH) and limonite (containing Si and OH). In addition, the signs of corrosion of magnetic minerals and newly crystallized magnetite (maghemite) were recognized. Differences in the composition and assemblage characteristics of magnetite minerals between XS and DS reflect significant differences in source rocks and preserving conditions.

关 键 词：磁性材料 黄土 古土壤 可结晶性 光学微观结构 物理性质 

分 类 号：P618.2[天文地球—矿床学]