CHARACTERISTICS OF DIAGENETIC SECONDARY MINERALS IN THE SANDSTONE OF THE SONGLIAO BASIN

During the diagenetic process of sandstone,secondary minerals were up to more than 20 kinds.The formation of secondary quartz,albitite,calcite and laumontite affected the storage physical properties of sandstone in different degrees.The SiO₂ forming secondary quartz mainly came from the transformation of dissolved clay mineral in clastic feldspar.Secondary feldspar was related to the albitization process of feldspar,the albitization of plagioclase began at the early stage of diagenesis,and the albitization of K feldspar can only underway under higher diagenetic conditions.Secondary calcite was mainly inorganic CaCO₃ deposit in the early stage of diagenesis.Laumontite was stable mineral in the late diagenetic stage,and was related to the albitization in the late stage of diagenesis.