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~ Y ~I I' ~ ~ l , <br />lathe). Nearly all of the productive oineralizatlon found in the Sungyside Nine has <br />come from veins Hosted by upper Burns. A latter period of rolcanlc activity resulted <br />in the formation of the S1lverton Caldere about 27.5 million years ago., Yithln the <br />immediate mine area the volcanic rocks ha re gentle southwesterly dips. <br />auiur <br />~~ <br /> <br />-~~~ <br />_ ~ <br />~ ` <br />1 <br />1 <br />~t f <br />'~ J <br />~~' <br />~.~ <br />/"/.~ "_ i <br />SUNNY5IDE <br />MINE <br />~ y <br />tR <br />• ~qls \ 1!t N/ <br />GENERALIZED GEOLOpC MAP SNOWING LOCATION OF SU~1VY510E NINE <br />AND EUREKA GRABEN N RELATION TO CALDERA CENTERS, <br />Rocks throughout the mine area show pervasive pre-ore propylitic alt~aration. the <br />most obvious effect being a green color. Hine development and deep diamond drilling <br />Indicate the mineralogy of the propylitic alteration changes with depth (Casadevall, <br />1976). Mithin 2.000 feet of the surface chlorite-epidote-pyrite and calcite <br />characterize the alteration. Between 2.000 and 4,000 feet an asserblage of chlorite- <br />pyrite-epidote-treaolite-actinolite and anflydrite becomes prominent. Below 4.000 <br />feet quartz-serlcite-andradite and pyrite dominate and the alteration mineralogy. <br />The zoning of propylitic alteration probably reflects both changes in lithology and <br />changes in pressure. temperature and fluid composition with depth. <br />63 <br />