GEOCHEMICAL CHARACTERISTICS OF CARBONATE ROCK DIAGENESIS

The paper deals with the distribution of trace elements,such as Sr.Na,Fe.Mn in carbonate rocks occurred under various diagenetic environments with a case study of the carbonate rocks(Z-T)in the Chao County.The limestones(O,upper part of C1h.C2h.C2c)origined mainly from meteoric diagenesis are characterized by low concentrations of Sr(188ppm),Na(132ppm),Mn(149ppm),while the limestones(Clj,lower part of C1h.P1q,T1n)mainly derived from submarine diagenesis by high concentrations of Sr(515ppm),Na(396ppm),Mn(404ppm).The penecontemporaneous sabkha dolomites(T2d),in comparison with penecontemporaneous-back poly-origin dolomites(Z-∈)which origin mainly from diagenesis dolomitization,has high concentrations of Sr(138ppm),Na(806ppm),and the later have low concentrations of S(103ppm)and Na(604ppm).It is significant for the difference in Mn content between the dolomites.The dolomite rocks,in comparison with the limestones,have high Na and low Sr,Mn.Moreover,it is obvious that Fe content tends to be negative correlation with Ca+Mg content and it is suggested that Fe content should be influenced by terrigenous cleposits.