庐山地区第四纪泥砾沉积物的成因探讨  

ORIGIN OF QUATERNARY MUDDY GRAVEL DEPOSITS IN THE LUSHAN AREA

作　　者：刘宗秀[1] 赵志中[1] 田姣荣[2] 王敏[1] 李名则[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]庐山风景名胜管理局国土资源局,江西九江332900

出　　处：《地质力学学报》2007年第4期322-332,314,共12页Journal of Geomechanics

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，9值相对较小，平均为0．66，F值相对较大，在2左右，F/ψ比值介于2．75～4．75，P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06面都倾向沟谷下游，a轴倾角集中且较小，为7—8°，曲面倾角为7～21°，a轴较曲面具有更为优势的组构倾向；沉积物粒度频率曲线在4～5 φ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。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%w37.75% ; the ratios of F/ψ range from 2.75 to 4.75 ; the ψ 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 ° ; 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.

关 键 词：庐山 泥砾 组构特征 冰碛物 

分 类 号：P534.63[天文地球—第四纪地质学] P512.4[天文地球—古生物学与地层学]