摘要
磷块岩胶结物有泥质、硅质、磷质和碳酸盐质４种，共形成１９种胶结结构，其中尤以磷泥晶环边结构、等厚纤状环边结构、似重力式结构、磷质纤状环边叠加云质亮晶充填结构特征突出，具有指示沉积成岩环境的意义．４种类型的胶结物在剖面和平面上的演变与水体深度和沉积成岩环境有关，而胶结作用的地球化学特征，既是磷块岩的环境指示，又反映微生物的影响状况．
Having studied the industrial phosphorite deposits in different parts of China,we find that there are four kinds of cements in the phosphorites,i.e..argillaceous,siliceous,phosphate and carbonate cements.They form 19 types of cementation texture:four argillaceous,eight phosphate,four dolomite and three siliceous. Among them,the micrite-phosphate rim texture,the equal-thickness fibrous phosphate texture, thegravity-b3ng texture and the texture of pore-filling dolomite within fibrous phosphaterims are very distinct and can be used as indicators of sedimentary and diageneticenvironments.The four kinds of cements have regular spatial occurrence. From bottom to top of a profile or from the center to the margins of a basin,cements areusually changed from siliceous through argillaceous and phosphate to carbonate.Thecementatiolt processes of phosphorites had been affected by micro-organisms.The δ18Oand δ13C values in the cements are usually negative,and pH values range from weakalkaline to alkaline.The Eh values were negative during precipitation of the argillaceous,siliceous and micrite phosphate cements,but positive during the precipitationof fibrous phosphate and dolomite cements.The behaviors of trace elements in phosphorites show that the water medium was more dense and saline but less influencedby terrigenous materials during the cement precipitation than during the phosphategrain sedimentation.The change of cement components and cement textures in phosphorites are closely related to the sedimentary and diagenetic environments. So we can use the differences of the cement components and textures as atool to reconstruct their environment s.
出处
《地质科学》
CAS
CSCD
北大核心
1994年第1期62-70,T002,共10页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金
关键词
磷块岩
胶结作用
成岩作用
类型
Phosphorite；Cementation；Diagenesis；Cementation texturetypes
