中文摘要：

利用扫描电镜和能谱分析研究了长白山天池火山天文峰剖面全新世喷发物中长石表面风化溶蚀显微形貌和化学组成,结果显示：天文峰剖面从顶部黑色浮岩向下到暗灰色浮岩中,长石表面发育风化溶蚀不同的显微形貌结构。其特征有,风化初期的溶蚀作用主要在双晶缝、解理缝等结构薄弱部位,形成规模较小的溶孔和溶缝等,随着风化溶蚀程度的增加,已经形成的溶蚀痕迹进一步扩大、合并、相互贯通而形成矩形溶孔或棱柱状溶孔。长石晶体上溶蚀痕迹的扩大受长石晶体各向异性的控制。天文峰剖面火山喷发物时代越早,长石颗粒表面风化溶蚀程度越强,结构越复杂;火山喷发物时代越晚,长石颗粒表面风化溶蚀程度越弱,结构越简单。即长石表面风化溶蚀程度与火山喷发的时代具有一定的相关性。根据长石颗粒表面的显微形貌结构,认为漫江林场浮岩与天文峰剖面中灰色浮岩应是火山同一次喷发的产物。长石表面风化溶蚀度可以作为判定火山喷发精细序列的一个代用指标。能谱分析显示,较新鲜的长石表面与风化溶蚀的长石化学组成不同。长石风化溶蚀的显微形貌和化学组成反映了它是天然风化、溶解、淋滤,最后又有物质沉淀的自然成因。Fe元素则可能与微生物作用有关。详细研究长石表面的风化溶蚀特征,它将有可能成为从岩石微观方面探讨火山喷发后环境变化和火山喷发期次的一种新方法。

英文摘要：

We use SEM and EDX to study the micro structures and chemical compositions of feldspar surface weathering dissolution in Holocene volcanic eruptive material at the Tianwen peak,Tianchi,Changbaishan.The result shows that there are varied micro structures formed by weathering dissolution on feldspar surface in the pumice which is black on the top and turns dark-grey downward on the cross section at the Tianwen peak.Their structural features are described as follows.At the early weathering stages,small-sized solution openings and fissures were produced by dissolution at weak structures such as twin crystal and joint fissures.With increase of weathering dissolution,these dissolution products on the surface of feldspar became larger and emerged,controlled by the anisotropy of the feldspar crystals.For the earlier eruptive material（at lower level of strata）,the dissolution degree is stronger and the structure is more complex.On the contrary,for the later eruptive material（upper level of strata）,the dissolution is weaker and structure is simpler.It implies that the degree of weathering dissolution on the feldspar surface is correlated with ages of volcanic eruptions.Observations on the microstructure of feldspar surface suggest that the pumice at the Manjiang tree farm and the grey pumice at the Tianwen peak cross section are the product of the same one volcanic eruption.And the weathering dissolution degree of feldspar surface can be used as an indicator to determine the sequence of volcanic eruptions.Energy spectral analysis indicates that the fresh feldspar and that suffered from weathering dissolution have different chemical compositions.The microstructure and chemical composition of the feldspar that had experienced weathering dissolution resulted from a natural process of weathering,solution,leaching and precipitation.The element Fe in it is probably related with function of microorganism.The detailed analysis of weathering dissolution of feldspar surface can help study environmental change after volcanic