CHEMICAL ZONING OF FLUORITE AND QUARTZ IN HYDROTHERMAL VEINS FROM THE LAKE GEORGE PLUTON OF THE PIKES PEAK BATHOLITH, COLORADO

In Lake George, Colorado there is a billion year old granite batholith known as the Pikes Peak Batholith. Within this batholith are six satellite plutons. Lake George pluton consists of four granites: quartz syenite to fayalite granite, syenite, fine-grained granite, and medium-grained granite. The samples collected for this study were found in the quartz syenite to fayalite granite which, according to Wobus, R.A. and Epis, R.C., 1978, forms a partial ring dike. On June 12, 2015, field exploration was conducted at Lake George by the University of West Georgia students. While exploring the Pikes Peak Batholith at Lake George, the students discovered an old unmarked claim where hydrothermal veins had been dug out of the Lake George Pluton. The site was found at an elevation of 8316 feet located at N38° 59.142’ and W105° 21.007’.

The granite found at this site appeared to be a pink, medium to coarse grained k-feldspar, biotite, and quartz. The granite had hydrothermal veins and was observed to be from a few millimeters thick to several centimeters thick. Along the contact between the vein and the granite were fluorite crystals which range in size from 0.4cm x 0.8cm to 1.4cm x 1.9cm, with a layer of what appeared to be brecciated granite. After the fluorite there were quartz crystals which are 0.1cm x 0.1cm, that came in and filled in the rest of the space. All of the minerals appear to be growing towards the inside of the vein.

Thin sections were made to examine the sequence of minerals of the hydrothermal vein. Optically there were two main minerals which were identified to be fluorite and quartz. In thin section, the fluorite is euhedral and there is drossy quartz is coating the fluorite crystals. The hydrothermal vein of fluorite and quartz are filling in the pore space of a brecciated wall. The fluorite and quartz are getting larger towards the center of the vein. The primary mineral is fluorite and the secondary mineral is quartz. Chemical zoning analysis will be conducted using the scanning electron microscope (SEM). The focus of this research is to study the chemical zoning characteristics of fluorite and quartz in hydrothermal veins.