陆良盆地彩色沙林沉积-成岩特征及其景观成因分析

Sedimentary-Diagenetic Characteristics and Landscape Genesis of Colored Sand Forest in Luliang Basin

通过分析露头剖面、岩石微观组构及主量元素等特征,探讨了陆良彩色沙林成景地层沉积环境、成岩作用及景观形态、颜色成因.研究结果表明:(1)彩色沙林成景地层为茨营组,该组沉积环境为扇三角洲相、辫状河相及滨浅湖亚相,其中砾石成分主要为碎屑岩及变质岩,磨圆度及分选性较差,砂岩类型主要为中细岩屑砂岩,颗粒以点接触为主;(2)研究区茨营组砂岩在同生成岩阶段至早成岩阶段A期形成的铁、锰氧化物是影响砂岩固结的关键因素.铁、锰氧化物及有机质含量及分布使砂岩颜色改变;(3)茨营组的沉积环境、成岩作用及构造作用是导致岩石形态及颜色变化的主要因素.

Through analyzing outcrop profile,major elements,and the micro-fabric of the rock in the Colored Sand Forest,the sedimentary environment,diagenesis characteristics,genesis of landscape morphology,and the existence of different colors for the bedrock of the Colored Sand Forest in Luliang were discussed in detail in this study.The results are as follows:(1)the bedrock of the Colored Sand Forest is Ciying Fm whose sedimentary environment is composed of fan delta facies,braided river facies,and shore shallow lake subfacies.The main ingredients of gravel are clastic and metamorphic rocks,which are poor in terms of roundness and sorting.The main kind of sandstone is medium-fine lithic sandstone,and its particles are primarily point-contacting.(2)through sandstone thin sections,scanning electron microscope,and major element analysis of the sandstone,wefound that the iron oxides and manganese oxides formed from the syngenetic stage to the early diagenetic stage A were the key factors affecting sandstone consolidation.The content and distribution of iron oxides,manganese oxides,and organic matter enable the sandstone to change color.(3)The sedimentary environment,diagenesis,and structures of the Ciying Fm are the key factors that contribute to the change in rock morphology and color of the Colored Sand Forest.