U.S. Geological Survey-Ingeominas mineral resource assessment of Colombia; ore deposit models

Abstract

This compendium of ore deposits models was assembled for the Colombia Mineral Resource Assessment Project. The objectives of the compendium are: (1) to define mineral deposit types so that all project members have a common vocabulary or deposit classification scheme to which mineral occurrences, favorable geologic environments, favorable geochemical anomalies, and tonnage-grade models may be related; (2) to provide data on the environments of ore deposition so that favorable rocks, structures, and tectonic settings can be easily recognized by project geologists; and (3) to relate possibly the associations of elements within geochemical anomalies to specific deposit types so that geochemical data may be more easily interpreted. A key-word index and an element association index are included to help in achieving the second and third objectives.The compendium is not complete at this stage and many models useful in the Colombia assessment still need to be added. Appropriate models for the Proterozoic shield environments of eastern Colombia are needed.Alteration; Minerals produced by reaction of ore-forming fluids with rocks.List in assemblages. Show zonal or temporal relation between assemblages. Use terms such as potassic (potassium-feldspar+biotite), phyllic (white mica+pyrite), argillic (clay4white mica), advanced argillic (clay+pyrophyllite+alunite+A^O^ minerals) as they apply. Include skarn mineral assemblages where appropriate.Ore controls; List special stratigraphic, structural, or geochemical features that are believed to have influenced ore-mineral deposition.Weathering; Optional. List any special weathering characteristics or secondary minerals that might serve as prospecting guides.Geochemical signature; Elements expected to be anomalous (enriched or depleted) in and near the deposit. List element assemblages and show zonal arrangement where possible.Examples; A Colombian or Andean example should be included where possible.References; One reference for each example. Give name and year. Include complete reference on a separate sheet. Additional information neededSketch; Where possible, include a well-labeled map or section of a deposit, or a cartoon of an ideal deposit, showing ore controls, zoning, and approximate dimensions.

Geochemistry of Some Tertiary and Early Cretaceous Basaltic Exposures around Gulf of Suez (Emphasis on Significance of High Field Strength Elements and their Ratios), Egypt

“…This suggest the same mantle source ;2-The LREE / HREE ratio of Tertiary basalt are similar but lower than that of Abu Darag Early Cretaceous basalt . [26] found that the high field strength element ratios remain unmodified for basalts of the same mantle source; [27] . The continental crust of Egypt is thinner in the northern part [3].This may explain the oceanic affinity of some Tertiary basalt in the northern part of Egypt and may be related to Red Sea opining, 5-The chemical weathering has increased LOI, MgO and K 2 O and decreased CaO from the marginal part of Abu Darag basaltic dyke, upper part of Abu Zenima flow and Ehamer dyke, resulting in modified major element compositions.…”

Mineral resources of the Sacatar Meadows Wilderness Study Area, Tulare and Inyo counties, California

“…The study area is situated in the Sierra Nevada physiographic province, which contains the largest concentration of tungsten deposits in the United States (Newberry, 1982). The mineral-deposit model that is most appropriate to apply in this study area is the tungsten-skarn felsic-plutonic-rock model (Einaudi and others, 1981;Cox, 1983;Cox and Singer, 1986). Tungsten skam deposits form along contacts and in roof pendants of batholiths and in thermal aureoles of apical zones of stocks that intrude carbonate rocks.…”

Modelos de yacimientos minerales (Mineral deposit models)

“…La presente forma de los modelos descriptivos en una pagina se elaboro por Dennis Cox, Donald Singer y Byron Berger y el metodo grafico para presentar los dates de ley y tonelaje se realize por Donald Singer. En el proyecto colombiano se utilizaron 65 modelos descriptivos (Cox, 1983a y b) y 37 modelos de ley-tonelaje (Singer y Mosier, 1983a y b).…”