Abstract: By means of core description and rock thin section observation,the Cambrian and Silurine dolostones penetrated in eastern Tarim Basin recent years are studied.It is recognized that the dolostones in the area are mainly composed of crystallized dolostone(coarse crystal,mid-crystal,fine crystal,silt crystal and silt-dolomicrita),residual algal lamina dolostone and residual oolite dolostone.The geochemical analysis of Carbon and Oxygen isotopes,homoinclusion temperature measurment,dolomite order degree and rock slide inspectation indicates the dolostones can be divided into three types of genesis,i.e.,high temperature hydrothermal fluid dolomization,seepage reflux dolomization and mixed water dalomization.Among them,the first type is the most favorable for the development of pore space in the area.

Key words: Eastern Tarim Basin, Sinurian, Cambrian, dolostone, genesis