Marble - Colorado Geological Survey

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ock unit known as the Molas Formation. This formation, which has been mapped as being up to 50 feet thick southwest of the area, is missing in the Aspen-Conundrum area. Where lower Belden rocks are sufficiently exposed due to contact metamorphism, as at the Conundrum Creek property recrystallization and deformation have destroyed necessary indicators for determination of a lower Belden contact. The Belden Formation is of importance economically, as this is the zone of marble being considered in this report. IGNEOUS ROCKS Overview Laramide and Middle Tertiary age igneous rocks have been emplaced throughout the Elk Mountains in the form of dikes, sills, lacoliths, and plutons. Laramide age intrusive rocks of both mafic and felsic affinity occur predominantly as sills. Laramide igneous rocks described thus far in the Aspen area include hornblende quartz diorite, quartz porphyry, aplite, and aplite porphyry. All of these intrusive rocks have been recognized in the Conundrum Creek area. None of these rock types were mapped in the vicinity of the Colorado Highland Marble quarry property by CGS. Middle Tertiary age (Oligocene) calc-alkalic igneous rocks comprise a number of large plutons and associated dikes, sills, and lacoliths. The major rock types are granodiorite, granodiorite porphyry, and hornblende porphyry. The Oligocene plutons have been emplaced along a regional zone of weakness (the Elk Range Thrust Fault) with which they are generally concordant. The plutons are also concordant with bedding in gross aspect, but occasionally cross-cut strata. Figure 3 shows the outcrop pattern, and some structural relationships of the Oligocene plutons. The White Rock pluton is of particular interest because of extensive areas of associated contact metamorphism which have produced the marble and hornfels of the Conundrum valley (Bryant, 1979). White Rock Pluton The White Rock pluton outcrops in a roughly circular pattern in the southeastern part of the Elk Mountains. Rocks of the pluton make up the jagged peaks at the head of Castle Creek, part of Conundrum Peak, the ridge north of Hayden Peak, Keefe Peak, and the crest of the Elk Mountains at the head of East Maroon Creek. Major exposures of the pluton in the study area are the north ridge of Hayden Peak, a large mass on hill 12,146 between Cataract and Conundrum Creeks, and along the plane of the Elk Range Thrust which cuts the western side of the Vermont Placer on the west side of Conundrum Creek. Just north of the Vermont Placer claim, rocks of the White Rock pluton form the prominent cliffs on the west side of the valley. Rocks of the White Rock pluton are granodioritic. The granodiorite is white to gray rock composed mostly of plagioclase feldspar, with lesser amounts of quartz and potassic feldspar. Accessory minerals are biotite, hornblende, pyroxene, and magnetite. The pluton displays chemical variation with small areas of more mafic phases occurring at or near margins of the pluton. Country rocks at the contacts of the pluton lack chilled margins and are generally not deformed due to intrusion. An exception is rocks of the Belden Formation which are highly deformed near contact with White Rock plutonic rocks. Country rocks have been subjected to contact metamorphism, especially in areas where the intrusive contact is discordant. Exposures of the White Rock pluton south of the Colorado-Highland Marble Quarry contain substantial quantities of pyrite which is generally disseminated, but can occur as micro-fracture fillings or in large masses up to four inches in diameter (Figure 4). Where sulfides occur in the pluton, alteration is most pronounced. Fluid inclusion studies conducted by J.T. Nash and C.G. Cunningham, Jr. show this to be postmagmatic alteration which most likely occurred a million to a few million years after emplacement of the pluton. Also associated with this late stage alteration are mineralized fracture zones containing quartz and/or carbonate, and pyrite. Some of these zones are reported to 9
Oligocene plutons Precambrian basement in Sawatch uplift 107° EXPLA NATION Fault Thrust fault; teeth on upper plate Syndine; arrow at end indicates direction of plunge Overturned syndine Anticline Dome Monocline Figure 3; Structural and spatial relationism associated with the White Rock pluton ship of Oligocene plutons in the Elk Moun is extensive and has produced marbles tains. White Rock and Snowmass plutons and hornfels. These metamorphic rocks have been emplaced along the Elk Range are exposed in the Conundrum Creek Thrust Fault. Zone of contact metamorph window (from Bryant, 1979). 10
Page 1 and 2: CGS LII Open-File Report 90-2 Geolo
Page 4 and 5: EXECUTIVE SUMMARY *. .....1 INTRODU
Page 6 and 7: The Colorado Geological Survey (CGS
Page 8 and 9: night can be more pronounced in win
Page 10 and 11: GEOLOGIC CHARACTERIZATION INVESTIGA
Page 12 and 13: content. A Geometries GS 101A scint
Page 16 and 17: contain galena, sphalerite, and cha
Page 18 and 19: 6? J® •—y "iff i &-m*--&-.~s I
Page 20 and 21: EXPLANATION Upper Tertiary volcanic
Page 22 and 23: closing of the Midnight Mine near R
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Page 28 and 29: the greatest potential for gold. Th
Page 30 and 31: The economic evaluation for the Col
Page 32 and 33: Country of Origin Italy Spain Greec
Page 34 and 35: quarries, may be nothing more than
Page 36 and 37: White Marble (Pbwm) White marble is
Page 38 and 39: Textbook, Economic Evaluation and I
Page 40 and 41: the end of the year taken. The prod
Page 42 and 43: increase back support costs. A 20 f
Page 44 and 45: The CGS has determined that the occ
Page 46 and 47: Barton, W. R., 1968, Dimension Ston
Page 48 and 49: APPENDIX A Description of Rock Samp
Page 50 and 51: contains inclusions of dark gray cl
Page 52 and 53: dote, is tightly cemented by silica
Page 54 and 55: (67) Quartzite, dark greenish gray
Page 56 and 57: INDIANA DEPARTMENT OF NATURAL RESOU
Page 58 and 59: DIRS 120 INDIANA DEPARTMENT OF NATU
Page 60 and 61: SKYLINE LABS, INC. SPECIALISTS - EX
Page 62 and 63: SKYLINE LABS, INC. SPECIALISTS IN E
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ALLIED ENVIRONMENTAL SERVICES, INC.
Page 66 and 67:
Designers Tile and Marble, 1928 Eas
Page 68 and 69:
U.S. Bureau of Mines, Washington, D
Page 70 and 71:
Title: Four months production Proje
Page 72 and 73:
Title: Five month production with T
Page 74 and 75:
(Title: Five months production Proj
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Title: Six months production with T
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Production Calculations Cubic Feet
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Tile Blocks Assume: 1) from broken
Page 82 and 83:
large samples of geologic material:
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Marble - Colorado Geological Survey

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