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r~ <br />5N <br />EXHIBIT D <br />D.1 <br />1 <br />iii iiiiiiiiiiiu iii <br />999 <br />MINE PLAN <br />l l_g, 8d <br />Pro.iect Geoloov and Seismicity <br />D.1.1 Geoloov <br />' The San Luis Project area lies in an area of complex <br />structural geology between the San Luis Basin to the west and <br />' the Sangre de Cristo Mountain Range to the east. <br />The San Luis Basin is a complex, eastward tilting graben, <br />' which forms part of a series of en echelon graoens known as <br />the Rio Grande Rift. The Rio Grande Rift extends from E1 Paso, <br />' Texas to Leadville, Colorado, and possibly further north. The <br />main fault zone of the Rio Grande Rift is the Sangre de Cristo <br />' Fault which runs north-south along the edge of the Sangre~de <br />Cristo Mountain Range. <br />' In the northern portion of the San Luis Basin, the Sangre <br />~_ de Cristo Fault abruptly cuts the Basin, and the Sangre de <br />' Cristo Mountains rise from the edge of the Basin. However, west <br />of the project area, the displacement of the Sangre de Cristo <br />' Fault is thought to be distributed across a '.aide zone of step <br />faults which exhibit downward displacement to the west with <br /> the main arm of the Fault lying at the eastern edye of the San <br />' Luis Basin. figure D.1-1 shows the main arm of the Fault in <br /> the vicinity of the proposed project. Numerou s smaller faults <br />' are evident in the project area. The period of the faulting <br /> has not been clearly defined. Estimates range from late in the <br />' Laramide Orogeny (late Mesozoic to early Tertiary) to after <br />the Laramide Orogeny in late Tertiary. <br />' The stratigraphy within the proposed project area is <br />' comprised of four basic units. The most recent deposition is <br />a band of quaternary alluvial sediments that have been <br />deposited along the Rito Seco. <br />1 <br />D-1 (Exhibit D revised 2/15/89) <br />-, <br />