[en] The need to accurately represent the law of the Colorado River has heretofore precluded the use of any general purpose river basin simulation model. In order to overcome the inflexibility associated with policies coded directly into a model, a new approach for river basin simulation modeling has been developed. The new approach allows the user to capture the operating policy in a series of policy statements separate from the basic simulation model. These statements are accessible without writing code and may easily be modified to explore policy alternatives

[en] The author presents information on the discovery, vein structure, trace metals, surface expression, mining methods and ore handling system. 5 refs

No abstract available

[en] Gravity and aeromagnetic surveys covering about 15,000 square miles in the central Colorado Plateau in Utah, Colorado, Arizona, and New Mexico were conducted to assist in determining the regional subsurface geology as it may relate to uranium, oil, and potash exploration. The dominant gravity anomalies are conspicuous gravity lows over the salt anticlines. Both broad regional highs, which occur over the monoclinal uplifts where denser rocks are close to the surface, and regional lows, which occur over the basin and platform areas, are caused by lateral density contrasts related to structural relief. Most of the magnetic anomalies arise from contrasts in magnetization of the Precambrian basement

No abstract available

[en] The most likely volcanic source rock for uranium in epigenetic deposits of the Tallahassee Creek uranium district and nearby areas is the Wall Mountain Tuff. The widespread occurrence of the Tuff, its high apparent original uranium content, ∼ 11 ppm, and its apparent loss of uranium from devitrification and other alteration suggest its role in providing that element. An estimate of the original Th/U ratio is based on the present thorium and uranium contents of the basal vitrophyre of the Tuff from Castle Rock Gulch, Hecla Junction, and other areas. The Gribbles Park Tuff also could have supplied substantial amounts of uranium. Its presently high thorium content suggests an original uranium content similar to that of the Wall Mountain Tuff, but little data are available upon which to base an estimated Th/U ratio. The remaining units that were evaluated include the lower member of the Thirtynine Mile Andesite and related rocks, the Badger Creek Tuff, the Antero Formation, the Gribbles Park Tuff, and the Thorn Ranch Tuff. 36 refs.; 8 figs.; 9 tabs

[en] The Colorado School of Mines (CSM), under sponsorship of the Department of Energy through the Office of Nuclear Waste Isolation (ONWI), has established a hard-rock research facility at its experimental mine. Even through this site will not become a nuclear waste repository, the CSM has established and maintains an underground test room for use by its own personnel and ONWI and its contractors to conduct in situ investigations. Furthermore, CSM is designing, conducting, and reporting on a series of field research programs to develop site evaluation procedures, excavation techniques, and instrumentation required for nuclear waste repository siting, construction, and monitoring (Hustrulid, 1981). This facility is presently being used to: evaluate and develop techniques for careful excavation of hard rock; develop the mapping techniques required to describe adequately the structural geology; evaluate the structural continuity in the granitic gneiss at the CSM site; evaluate the structural damage done to the rock mass by blasting; develop techniques for evaluating fracture permeability; evaluate permeability changes in the rock mass as a result of blasting. Although specifically oriented toward nuclear waste storage and disposal, the techniques and procedures being developed and evaluated have wide applicability to all underground excavations in hard rock

[en] This report is an analysis of the various types of uranium occurrences in the Colorado Front Range and the environments in which they developed. The early Proterozoic crust of this region is believed to have been a platform on which intermediate to felsic volcanic centers formed. Some units in the volcanic stratigraphy as well as in the sediments which were deposited in the shallow, intervening seaways are thought to have been uraniferous. Tectonism, occurring about 1.7 By ago, was accompanied and followed by three periods of Precambrian igneous activity. The volcanics and sediments were converted to a metavolcanic-metasedimentary sequence known as the Idaho Springs Formation. Some of the syngenetic uranium remaining in the volcanics and sediments after metamorphism may have been mobilized and incorporated within the Silver Plume plutons and the Pikes Peak batholith and concentrated in pegmatite dikes, pegmatites and fractured areas in the hood zones in the apophyses, or along the flanks of these intrusives. Some or most of the uranium found in these sites may have been generated deeper in the continental plate. Uplift of the Front Range in the Late Mississippian and arching during the Laramide with accompanying faulting set the stage for early and mid-Tertiary igneous activity and associated uranium mineralization. The source of the early and mid-Tertiary uranium mineralization is a point of current debate. Exploration for uranium in the igneous and metamorphic terrain of the Front Range is summarized, and models of each major uranium occurrence are described. Finally, the Front Range exploration potential for uranium is outlined

[en] For the first time in history, water was intentionally released for environmental purposes into the final, otherwise dry, 160-km stretch of the Colorado River basin, south of the Mexican border. Between March and May 2014 three pulses of water with a total volume of 132 × 10"6 m"3 were released to assess the restoration potential of endemic flora along its course and to reach its estuary. The latter had not received a sustained input of fresh water and nutrients from its main fluvial source for over 50 years because of numerous upstream dam constructions. During this pulse flow large amounts of water were lost and negligible amounts reached the ocean. While some of these water losses can be attributed to plant uptake and infiltration, we were able to quantify evaporation losses between 16.1 to 17.3% of the original water mass % within the first 80 km after the Morels Dam with water stable isotope data. Our results showed no evidence for freshwater reaching the upper Colorado River estuary and it is assumed that the pulse flow had only negligible influences on the coastal ecosystem. Future water releases that aim on ecological restoration need to become more frequent and should have larger volumes if more significant effects are to be established on the area. - Highlights: • Isotope ratios of oxygen and hydrogen quantify water lost through evaporation. • Evaporation losses between 16.1 and 17.3% during the 2014 Colorado River • Larger water volumes are required to influence the estuary ecosystem.

[en] The area is approximately 1,800 square miles and extends from Cripple Creek northward to Fairplay and Bailey. The Precambrian rocks include the metamorphic sequences of the Idaho Springs Formation and the Boulder Creek Granodiorite, Silver Plume Granite, Pikes Peak Granite, and Redskin Granite. The known uranium deposits in the area include six vein deposits, three pegmatite occurrences, and one zone of probable secondary enrichment; they have not yielded any significant production. The vein deposits are probably the result of downward percolation of ground water. The zone of secondary uranium enrichment may have formed above a volcanic pipe, vein, or tuffaceous lake bed. Favorability in the area is considered good for both vein and large, disseminated, low-grade uranium deposits. On the bases of known uranium occurrences, favorable structures and host rocks, and a water-sampling program, recommendations are given for exploration. The occurrences in the area have substantial similarities with the Rossing deposit in South-West Africa and the Wheeler Basin uranium occurrence in Grand County, Colorado. 6 figures, 9 tables