The Origin and Features of Late Sinian Phosphatic Stromatolites in Fuquan, Guizhou Province

来源 :Acta Geologica Sinica(English Edition) | 被引量 : 0次 | 上传用户:lovechenhua
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
The phosphatic stromatolite discussed in this paper is a columnar type, comprised chiefly of collophane and subordinately of microcrystalline apatite. The column is composed of alternations of dark, cryptocrystalline laminae formed by the biological processes of algae and bacteria, and light, microcrystalline laminae formed by chemical precipitation. The intercolumnar filler, showing a concave anti-stromatolitic structure, is composed of alternations of loose laminae formed by mechanical deposition, and dense, crypto-, microerystalline laminae formed by chemical precipitation and algal bacterial organic process.Under the SEM, the column differs clearly from the intercolumnar filler in ultramicro-fabric. The three basic types of ultramicro-laminae that can be distinguished in the column are: prismatic apatite laminae of chemical origin, elastic apatite laminae of mechanical origin and branched-tubular apatite laminae of algal-bacterial origin, of which the first and second categories constitute light laminae and the third, dark laminae. The dark and light laminae were formed during the alternation of flourishing and dormant periods of algae and bacteria.Under the SEM. the clastic texture is obvious in the loose laminae of the intercolumnar filler. Andfour types of ultramicro-apatite assemblages can be distinguished in the dense laminae, i. e., the framboidal and the tubular apatite of algal-bacterial origin, the framboidal-prismatic and the framboidaltubular-prismatic apatite of chemical organic origin. The alternation of the loose and the dense laminae depends upon the changes of the energy in the water.In the stromatolites, no replacement phenomena have been found and there exists abundant prismatic apatite kept in the initial form of upward-crystallization, and especially, in the forms of algae and bacteria(framboidal, tubular and branched). All these undoubtedly indicate that the stromatolites were originally formed by algae and bacteria.The ultramicro-fabric features indicate that the collophane is not a simple mineral, but a disorderly arranged aggregateof ultramicro-granular apatite. The phosphatic stromatolite discussed in this paper is a columnar type, composed chiefly of collophane and subordinately of microcrystalline apatite. The column is composed of alternations of dark, cryptocrystalline laminae formed by the biological processes of algae and bacteria, and light, microcrystalline laminae formed by chemical precipitation. The intercolumnar filler, showing a concave anti-stromatolitic structure, is composed of alternations of loose laminae formed by mechanical deposition, and dense, crypto-, microerystalline laminae formed by chemical precipitation and algal bacterial organic process. Under the SEM, the column soon clearly from the intercolumnar filler in ultramicro-fabric. The three basic types of ultramicro-laminae that can be distinguished in the column are: prismatic apatite laminae of chemical origin, elastic apatite laminae of mechanical origin and branched-tubular apatite laminae of algal -bacterial origin, of which the first and second categories co nstitute light laminae and the third, dark laminae. The dark and light laminae were formed during the alternation of flourishing and dormant periods of algae and bacteria. Under the SEM. the clastic texture is obvious in the loose laminae of the intercolumnar filler. Andfour types of ultramicro-apatite assemblages can be distinguished in the dense laminae, ie, the framboidal and the tubular apatite of algal-bacterial origin, the framboidal-prismatic and the framboidaltubular-prismatic apatite of chemical organic origin. The alternation of the loose and the dense laminae depends upon the changes of the energy in the water. the stromatolites, no replacement phenomena have been found and there exists abundant prismatic apatite kept in the initial form of upward-crystallization, and especially, in the forms of algae and bacteria (framboidal , tubular and branched). All these undoubtedly indicate that the stromatolites were originally formed by algae and bacteria. The ultramicro-fabric features indicate that the collophane is not a simple mineral, but a disorderly arranged aggregate of ultramicro-granular apatite.
其他文献
女性的错误观念在于:是你的跑不掉,用不着向人去要。而实际情况是:会叫才会有饭吃。所以,如何去积极地争取你应得的荣誉和报酬呢? Women’s misconception is: you can not
由安徽省地质矿产局第一水文地质工程地质队承担的“安徽淮河中游平原第四系分层”研究项目经过四年多的工作已于1986年底完成.该成果共50余万字,附图表200多件,内容相当丰富
一 有一地区,在元古代绢云母绿泥石片岩层中,广泛分布着铀的弱矿化现象,矿化带断续出现,出露面积很广,局部有加富现象。 矿化带的岩性,不同于一般灰绿色的绢云母绿泥石片岩,
采用DSC及DSC/TG-FTIR-MS联用技术研究了纳米基燃料空气炸药(FAE)中主要组分硝酸异丙酯(IPN)、高密度烃(HLF)、纳米铝粉在无氧条件和密封环境下的热行为。比较了纳米铝粉对FA
引言 制约外语阅读的因素很多,笔者暂且把所有的制约因素分为语言因素和超语言因素。语言因素包括读者对字母、单词、短语、习惯表达法、句子、语言规则以及阅读材料中句子
概览当前中国和泰国之间在贸易和投资方面的合作情况,有以下四个方面:①当前中泰贸易形势;②当前中泰投资形势;③中泰的贸易和投资机缘;④合作前景。一、当前中泰贸易形势从
农村党建示范点创建是基层党建工作的重要抓手,是具体落实先进基层党组织“五个好”和优秀共产党员“五带头”的有效途径。按照中央部署和省市相关要求,富民县自2009年始把基
(一) 分队概况及伯强测区地质矿产成果我们分队于一九七七年在全省一比二十万区调即新全面完成的时候组建的。是山西省第一个正规的一比五万区调分队。承担的任务是山西省五
土工织物散体桩是一种新型的地基处理技术,其工艺近似碎石桩,但在桩身外设置土工格栅筒,为了保证软土地基中碎石桩的承载力,对格栅筒的强度应有一定的要求,即格栅受到的环向
文章介绍了在水平层状地层模型中计算合成地震记录用的改进了的Cagniard法中大水平偏移距和大垂直偏移距的逼近法。上述两种逼近法可应用于分解地震波运动的各种广义射线成