GENERAL33488

• Permit No: C1981012
• IBM Index Class Name: General Documents
• Doc Date: 6/1/1984
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE for PR1
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

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Fork, Middle fork and South Fork which converge near the study area. The
study area ranges in elevation from 7,000 to 9,000 feet. Cottonwoods are
common on the floodplain of the Purgatoire River, whereas pinon, juniper,
gambel oak and mountain mahogany are common to the upland slopes.
A. Geology
The principal structural feature of the region is the Raton Basin, a broad,
asymmetric synclinal basin with an axis trending north-south. The eastern
limb is gently dipping in the study area and steeply dips further to the west
outside the study area. The Raton Basin was formed during the latter phases
of the Laramide Revolution when the Sangre de Cristo Range was thrust eastward.
The applicant has submitted geologic maps (Map 6) and geologic cross-sections
(Map 7) with each application. The Golden Eagle and New Elk Mines are located
on the western limb of the Raton Basin. The dip of the strata is 20 to the
northeast in the general area of the mines. The coal seam at the western
limit of the .Yew Eik Mine has a dip which increases to 14 to 16 degrees.
Several steep, normal faults, trending east-northeast have been mapped between
Weston and Starkville (Wood et al., 1957). Numerous faults have been mapped
in the New Elk Mine workings. These faults are all high angle faults (almost
vertical) and have low displacements. The maximum measured displacement of
faults in the New Elk Mine workings is between 15 and 17 feet. Most faults
pinch out within a very short distance. There are two major faults in the
area which are extensive. They strike N80oE.
The stream valleys overlying the existing New Elk Mine workings do not appear
to be fault-controlled. The New Elk Mine workings map, submitted on December
1, 1983, shows both surface streams and faults encountered during mining. No
extensive faults were encountered in the mine workings under the Middle fork
of the Purgatoire River, Pete Canyon, or Apache Canyon.
No faults have been encountered in the Golden Eagle Mine. Fbwever, during
mining, the applicant expects to encounter low displacement, high angle faults
similar to those encountered in the New Elk Mine.
Rock units in the Raton Basin range in age from Precambrian to Quarternary.
The stratigraphy of the study area consists of the Trinidad Sandstone, the
Vermejo Formation, the Raton Formation, and the Poison Canyon Formation.
The Trinidad Sandstone is the oldest and deepest of the sedimentary formations
listed above. The Cretaceous aged Trinidad Formation is a massive
intertongued sandstone which is an important marker strata in the Raton
Basin. The sandstone is fine to very fine-grained, light gray to buff in
color, and is slightly arkosic. The Trinidad Sandstone reaches thicknesses of
250 feet in the general area and is a prominent cliff former. This sandstone
is separated from the coal seams by up to 900 feet of interbedded shales,
silts tones, and sandstones.
The Cretaceous Vermejo Formation conformably overlies the Cretaceous Trinidad
formation. Typically, the Vermejo Formation consists of three lithologies;
slightly arkosic sandstone, carbonaceous shale, and coal. The Vermejo rapidly
thickens west of the town of Cokedale to over 300 feet.