PROVENANCE INTERPRETATION OF QUARTZ BY SCANNING ELECTRON MICROSCOPE-CATHODOLUMINESCENCE FABRIC ANALYSIS

We used a cathodoluminescence (CL) detector attached to a scanning ele ctron microscope (SEM) to study patterns of variable-intensity CL in q uartz grains from a variety of igneous, metamorphic, sedimentary, and shock-deformed (meteorite-impact) rocks. Distinctive fabrics in quartz grains revealed by SEM-imaged differential CL include zoning, healed fractures, complex shears, planar features (shocked quartz), dark CL s treaks and patches, indistinct, mottled texture, and nondifferential ( low-contrast) CL. Zoning is common in volcanic quartz and some plutoni c quartz. Zoned plutonic quartz is distinguished from volcanic quartz by the presence of closed fractures and dark CL streaks and patches. M etamorphic quartz displays either an indistinct, mottled texture, or n early uniform (nondifferential) CL. Quartz from rocks severely deforme d by tectonism displays a complex pattern of multiple, small-scale she ars. Quartz from meteorite-impact sites and some system boundaries is characterized by intricate patterns of planar features, presumably cre ated by shock metamorphism. Thus, the SEM-CL fabric-analysis technique provides a rapid method for distinguishing quartz from a variety of s ource rocks.