QUANTIFICATION OF QUARTZ CEMENTS USING COMBINED SEM, CL, AND IMAGE-ANALYSIS

Quartz cement content is often difficult to quantify using conventiona l petrography. Developments in equipment and technique reported here s how how excellent, high-contrast images of quartz cements can be produ ced using combined scanning electron microscopy and cathodoluminescenc e (SEM/CL). In most cases quartz cement can be differentiated readily from detrital quartz. Image analysis allows the percentage of authigen ic quartz to be quantified. Advantages of this method are: (1) it can be readily automated; (2) backscatter electron (BSE) and CL images can be compared directly, and (3) images can be improved through acquirin g and integrating multiple images. Comparison of results from conventi onal optical petrography with those from SEM/CL suggests that the perc entages of quartz cement determined by conventional methods are overes timated where quartz cement is present in high proportions and are und erestimated where quartz cement is less abundant. By adopting a statis tically rigorous approach to image collection, the abundance of quartz cement can be determined by SEM/CL with a known accuracy.