【摘要】 庐山第四纪泥砾沉积物的砾石组构特征表明,砾石岩性与山体基岩基本一致,砾石的等体积球径较小,加权平均砾径较中值砾径大,分选系数大于1,分选性差,φ值相对较小,平均为0.66,F值相对较大,在2左右,F/φ比值介于2.75~4.75,ρ值集中且较小,为22.75%~37.75%,砾石以棱角、次棱角状为主,磨圆较差;a轴和ab面都倾向沟谷下游,a轴倾角集中且较小,为7~8°,ab面倾角为7~21°,a轴较ab面具有更为优势的组构倾向;沉积物粒度频率曲线在4~5范围内表现为峰;石英砂颗粒为次棱角状,贝壳状断口发育,具平行擦痕、上翻解理片、V形坑和硅质沉淀。上述沉积学特征表明庐山第四纪泥砾沉积物系冰碛冰水沉积,而非泥石流或河流堆积。更多还原

【Abstract】 The gravel fabric characteristics of Quaternary muddy gravel deposits in the Lushan area indicate the following: the lithology of gravels is almost consistent with that of bedrocks in the mountains;the isometric sphere diameter of gravels is small,the weighted average diameter of gravels is lower than the median diameter of gravel;the gravels are poorly sorted with a sorting coefficient of >1;the values are relatively lower,averaging-0.66;the F values are higher,being 22.75%—37.75%;the ratios of F/φ range from 2.75 to 4.75;the φ values are lower and concentrated,ranging from 22.75 to 37.75%,and the gravels are mainly angular and subangular.Both the a-axis and ab-plane dip towards the downstream,the dip angles of the a-axis are low and concentrated,being 7—8°,the ab-plane dips at 7～21°,and the a-axis has more preferred dip of fabrics than the ab-plane;the peak of the grain-size frequency distribution curve of deposits in the Lushan area is in the range of 4 and 5 φ;The quartz sand grains are subangular and have well-developed conchoidal fractures,parallel striations,upturned cleavage flakes,"V"-shaped holes and siliceous deposits.The above-mentioned sedimentary characteristics indicate that the Quaternary muddy gravel deposits in the Lushan area should be till and glaciofluvial deposits rather than fluvial deposits or mudflows.更多还原