Abstract: Those nanometer-scale spherical-，rod-，or ovoid-shaped objects in the 25～300 nm range，which are visible in rocks and minerals by high-magnification(>50000×) scanning electron microscope(SEM)，atomic force microscope(AFM)，or transmission electron microscope(TEM)analyses，attract the geologists attention.For the origin of these nanometer-scale objects，different views result in a strong disputation.Because of the general resemblance between these objects and eubacterial cocci or bacilli，and because of their tendency to occur in chains or clusters，it was initially proposed that the objects were “dwarf forms” of bacteria，“nannobacteria”，or their fossilized equivalents，“nannofossils”.The focus of geologic objections to the actuality of nannobacteria is that features of this scale may have many possible origins，e.g.，micromineral inclusions or crystallographic edge effects;further，a sphere <140 nm diameter is biologically thought to be too small to contain all the components necessary for an independent life.Therefore，this disputation that occurred at the turn of centuries and had continued thus far became an important impetus promoting the studies of the origin of limestones although an affirmative conclusion remains uncertain.

Key words: nannobacteria, nannofossils, disputation, bacteria nucleation, carbonate sedimentology

摘要： 在高倍（>50000×）扫描电子显微镜（SEM）、原子显微镜（AFM）或透射电子显微镜（TEM）下，那些在岩石和矿物中所见到的纳米级别的物体常常吸引了地质学家们的注意。这些物体大小在25～300 nm之间，多呈球状、棒状或卵圆状；对这些物体的成因，存在不同的看法而导致了剧烈的争论。因为这些物体与真菌中的球菌和杆菌总体相似，而且它们总是以链状或束状的形式产出，所以被解释为细菌的“侏儒形式”或“超微细菌”，或者是它们的化石对等物即“超微化石”。对于超微细菌的存在，来自于地质学角度的反对聚焦在这个级别的特征物可能存在多重成因，如微矿物包裹体或结晶学的边缘效应；从生物学角度看，对于独立生命所必需的所有构成来讲，直径小于140 nm的球状体实在是太小了。因此，产生于世纪之交的这场争论，迄今还在持续着。尽管这场争论还没有一个肯定的结论，但是，它却成为研究灰岩成因的重要驱动力。

关键词: 超微细菌, 超微化石, 争论, 细菌成核作用, 碳酸盐沉积学

CLC Number: 

• P534