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~~ <br />The uppermost geologic unit over most of the project area <br />' is the Tertiary age Santa Fe Conglomerate. The Santa Fe <br />Conglomerate is a thick unit made up of gravels and cobbles <br />in a primarily silt and clay matrix. The Conglomerate is <br />' several hundred feet thick in the project area and is generally <br />considered absent above 8,800 ft in elevation. <br />t <br /> Below the Santa Fe Conglomerate lies t he Precambrian age <br /> pink gneiss. <br /> Below the pink gneiss is a biotite or biotite-amphibole <br /> gneiss. This unit forms the uppermost unit on the north side <br /> of the Rito Seco. In the areas of faulting and movement, the <br />' biotite gneiss and biotite-amphibole g neiss have been <br /> brecciated. <br />' The Santa Fe Conglomerate underlies the heap leach and <br />' mill facilities, as well as all waste rock disposal areas and <br />lower elevations of the pit areas. The brecciated biotite <br />gneiss and biotite-amphibole gneiss comprise the basal unit <br />' of the ultimate pit floors. <br />' A northwest-trending, low-angle thrust fault crosses tf~e <br /> western portion of the property. Along the fault zone, fault <br />' gouge, altered to green clay, is found. The clay layer acts <br /> as a confining unit over the West Pit area creating an aquifer <br /> of limited extent (see Exhibit G). This fault zone is absent <br />' in the East Pit area. Several smaller north-south faults also <br /> cross the property in the West Pit area. <br /> <br /> D.1.2 Seismicity <br />' <br /> The project area is located in a complex seismic zone <br />' referred to as the Southern Rio Grande Rift Subprovince of the <br /> Rio Grande Seismotectonic Province by Kirkham and Rodgers <br /> (1981). The Sangre de Cristo Fault is the major structural <br />' <br />M D-3 <br />