粤北金鸡岭丹霞群砂岩矿物表面结构初步研究

本文对丹霞群砂岩中的石英、长石、电气石、锆石４种碎屑矿物的表面结构特征作了初步研究，并与现代河流和海岸砂质沉积物中的同类矿物的表面结构特征进行类比。文章指出，由于成岩作用的影响，古代砂岩中的碎屑矿物比现代砂的同类矿物具有更为复杂的表面结构，原因在于成岩环境下，溶解、溶蚀和压溶作用对古代砂岩的矿物表面有更深刻的改造。

A Preliminary Study on the Surface Textures of Minerals from Sandstone of Danxia Group in Jinjiling Area,North Guangdong

The Danxia Group in Jinjiling area of north Guangdong is mainly composed of fluvial facies calciferous sandstone.On the basis of grain size analysis and artificial placer mineral analysis, four detrital minerals, i.e, quartz,feldspar,tourmaline and zircon were studied under a scanning electron microscope, and it is thus discovered that their surface textures are much more comlilex than the surface textures of similar minerals from any modern coastal and fluvial arenaceous sediments the authors have ever studied. The reason is that the surface of detrital minerals in ancient sandstone not only underwent transformation in the process of weathering, trapsportation and sedimentation like what detrital minerals are experiencing in modern rivers or coastal areas, but also suffered superimposition of further transformation during diagenesis. The composition of intergranular liquid and the change in temperature and in pH value under the diagenetic conditibns played an important role in the formation of surface textures of minerals. It is therefore obvious that the various characteristics of surface textures of minerals are related not only to mineral behaviors but also to the action and influence of the media in the diagenetic environment. A comparison of surface textures of various minerals shows that, in addition to the physical and chemical properties of minerals, the temperatures and pH values of the media in the diagenetic environment are also important factors affecting the formation of surface textures of minerals, with the main reaction being dissolution.The degree of transformation of the four minerals is in decreasing order of tourmaline-feldspar-quartz-zircon, which is not qcite consistent with the sequence of stability of these minerals.