DIAGENETIC HISTORY AND GEOCHEMISTRY OF THE BEEKMANTOWN-GROUP DOLOMITES (SAUK SEQUENCE) OF NEW-YORK, USA

Petrographic investigation using a cathodoluminescent microscope and a n electron microprobe for selected dolomite samples from the Beekmanto wn Group reveals six dolomite textures. These dolomite textures have b een classified based on crystal sizes, shapes, uniformity and trace-el ement distribution The textures are as follows: 1) unimodal, very fine ly crystalline, planar-e (euhedral) dolomite, 2) unimodal, very finely crystalline, planar-s (subhedral) colomite, 3) medium to coarsely cry stalline, planar-e (euhedral) dolomite, 4) coarsely crystalline, non-p lanar dolomite (non-saddle dolomite), 5) very coarsely crystalline, no n-planar dolomite (saddle dolomite), and 6) polymodal dolomite. Petrog raphic analysis of the selected Beekmantown dolomite samples records a timing sequence of diagenesis as follows: 1) deposition of the origin al sediments; 2) dolomitization; 3) silicification; 4) chemical compac tion (stylolitization); 5) dedolomitization; and 6) precipitation of s addle dolomite (pore-filling dolomite).