【摘要】 <正> 一、鉴定标志 偏光显微镜下薄片中生物化石碎片鉴定主要根据矿物组成、显微结构、显微构造和构造形态等四类标志。它们在各门类生物硬体中大致有一定的分布规律和演化特点。 (一)矿物组成更多还原

【Abstract】 In order to reconstruct the sedimentary environments and estimate the ore-bearing prospect of sedimentary sequence,it is necessary to recognize the fossil fragments in the thin section of sedimentary rocks.This paper deals with four aspects of diagnostic indexes.(1) Mineral composition containing dolomite,low-magnesium calcite,high-magnesium calcite,aragonite,apatite,opal,chalcedony and various kinds,of organic matter.(2) Microtexture,containing calcareous granular (agglutinated,crypto and micro-granular,crysto-granular and single-crystal),fibrous (lamello-fibrous,prismato-fibrous,prismato-lamello-fibrous,sphero-fibrous and hyalo-fibrous),sheet (foliated,crossed lamellar and nacreous),prismatic,and phosphorus lamello-fibrous,hyalo-fibrous,and foliated-fibrous.(3) Microstructure,including growth lamellae,arrangment of coelom,shell layering and perforated pore.(4) Structure,including shape,size,ornamentation,accessory structures and so on.Among them,the shape can be briefly divided into five forms: sphere,spicule and spine,multitube(with endotabula and without it),mo-notube or cone (straight,curved,and coiled),plate or valve (flat,arched,and crooked).We separately compiled four figures to summarize these aspects of diagnostic indexes for convenience to consult.In order to identify the fossil fragments accurately and quickly,we also made up a diagnostic table.The transverse line of the table represents the mineral composition and the microtexture of major shell layer,which are divided in-to 17 types in the table.The longitudinal line represents shape which is divided into 11 forms.As far as the limited informatics in hand,there are only 103 grids (subtypes) in which various hard parts of organism are distributed.It is common that two or more kinds of them are situated in a griid.so we must utilie other diagnostic indexes to distinguish them,such as size,microstructure,ornamentation,accessory structure and so on.For instance,crysto-granular coiled gastropods have no endotabula,so it can be distinguished from other two kinds.Having a large tube-diameter,more than 1 mm coiled tube subtype contains Gastropod,Cephalopod and Foraminifera,coiled cephalopods are easily distinguished from fusulinia foraminiferas whose tubediameter is less than 1 mm更多还原